WO2012002176A1 - Method for hardening surface of platinum molded article and platinum molded article having hardened surface - Google Patents

Abstract

Provided is a platinum molded article having a hardened surface, which has excellent self-weight deformation resistance even if the platinum molded article is thin, hardly deforms and is easy handle, has corrosion resistance and durability under high temperatures and pressure, and can prevent platinum particle growth and particle boundary corrosion in a reducing atmosphere, and also provided is a method for hardening the surface of a platinum molded article. The method for hardening the surface of a platinum molded article comprises: an application step for forming an application layer by applying an application solution containing an iridium salt and/or ruthenium salt to the surface of a platinum molded article (20); and a pyrolysis step for pyrolysis of the application layer in a nitrogen gas atmosphere or in a flame in order to convert the application layer to a coating layer (30) comprising iridium, ruthenium, or an alloy containing iridium and/or ruthenium.

Description

Method for curing surface of platinum molded article and platinum molded article with surface cured

The present invention relates to a method for curing the surface of a platinum molded article and a platinum molded article having a cured surface.

In recent years, in chemical reactions such as synthesis, decomposition, and crystal growth, processing using a solvent in a supercritical state is performed for the purpose of improving reaction efficiency, reactivity, and the like. Depending on the type of solvent to be used, for example, a hydrothermal synthesis method using water as a solvent, and an athermal synthesis method using ammonia as a solvent can be given. Such treatment can be carried out under high temperature and high pressure conditions in a pressure vessel called an autoclave. The processing conditions may be implemented, for example, in an ultrahigh temperature and ultrahigh pressure state of 800 ° C. and 4000 atmospheres. The single crystal synthesized using the pressure vessel is, for example, artificial quartz or zinc oxide in the hydrothermal synthesis method, and is, for example, gallium nitride in the low temperature synthesis method. These single crystals are used for various applications such as optics and electronic elements, and high purity is required. Therefore, the inner surface of the pressure vessel is required not to elute impurities in an ultra-high temperature and ultra-high pressure state, and is generally formed of platinum or a platinum alloy having excellent corrosion resistance and durability.

By the way, since platinum has heat resistance, is chemically stable, and is soft and easy to process, the molded product is used in a wide variety of fields such as physics and chemistry experiments at high temperature conditions and mining industry. However, platinum is easily deformed due to its softness. Moreover, since the specific gravity is large, if the thickness of the molded product is thin, it may be deformed by its own weight. Therefore, in order to maintain strength, it is necessary to increase the thickness of the molded product. However, as the amount of platinum used increases, there is a problem that the material price naturally increases and the molded product becomes very expensive. It was.

Therefore, the pressure vessel usually has a double structure in which the physical strength is held by an outer cylinder made of a nickel-base alloy, and a thin molded product formed of platinum for the purpose of corrosion resistance is used as the inner cylinder container. (For example, see Patent Document 1). However, since this inner cylinder container is very thin, deformation occurs due to its own weight (resistance to deformation due to its own weight, hereinafter referred to as “self-weight deformation resistance”), and handling such as attachment work to the pressure container body. There was a problem that became difficult.

It is known that alloying platinum increases strength, facilitates handling of a molded product, and further improves chemical stability (see, for example, paragraph 0033 of Patent Document 2). Moreover, although the use is different, a technique for improving chemical stability and physical strength by forming a film on a metal surface as an electrode structure for electrolysis has been proposed (see, for example, Patent Document 3). ).

JP 2002-102671 A JP 2010-53017 A JP 2006-130486 A

Platinum has the property of being heat resistant and chemically stable, but has the property of easily causing grain growth and intergranular corrosion in a high temperature reducing atmosphere. Therefore, when used as an inner cylinder of a pressure vessel that is exposed to a high-temperature reducing atmosphere such as a low temperature synthesis method, there is a problem that platinum is consumed quickly and the life of the inner cylinder is shortened. On the other hand, iridium and ruthenium are known to be stable against a high-temperature reducing atmosphere.

Platinum alloys are known to have better physical strength and chemical stability than platinum. However, when platinum is used as an alloy, there is a problem that workability is extremely inferior. There are almost no cases where these alloys are used as the inner cylinder of a pressure vessel. Further, as shown in paragraphs 0034 and 0035 of Patent Document 2, the pressure vessel is easily deformed in order to prevent the inner tube vessel from being deformed or damaged due to the difference between the internal pressure and the external pressure. However, it is preferable to install a pressure buffering mechanism such as a bellows structure for eliminating the pressure difference, but platinum alloys cannot be used for bellows because of their poor workability. Therefore, even if an alloy of platinum is used for the inner cylinder container, platinum is used for the bellows, which has a problem that the structure becomes complicated.

As described above, there is no platinum molded article that improves the strength of the platinum molded article so that it can be easily handled, and has improved corrosion resistance to such an extent that it can be stably used even in a high-temperature reducing atmosphere such as a low temperature synthesis method. Currently. Patent Document 3 proposes a technique for chemically and physically stabilizing the surface of a titanium base material by applying a precious metal coating to the surface of the titanium base material. This is a technology that forms a titanium layer and coats the electrode material containing noble metal on its surface, improving the strength of the platinum molded product, and preventing platinum from causing grain growth and intergranular corrosion in a reducing atmosphere. Not to do.

It is an object of the present invention to be excellent in its own weight deformation resistance even if it is thin, difficult to deform, easy to handle, has corrosion resistance and durability in a high temperature and high pressure state, and is a platinum particle in a reducing atmosphere. The object is to provide a platinum molded article having a cured surface and a surface hardening method thereof, which can prevent growth and intergranular corrosion.

The platinum molding surface hardening method according to the present invention includes a coating step of coating a coating liquid containing either or both of an iridium salt and a ruthenium salt on the surface of the platinum molding, And pyrolyzing the coating layer in a nitrogen gas atmosphere or in a flame to form the coating layer as a coating layer made of iridium, ruthenium, or an alloy containing at least one of iridium or ruthenium. .

The surface-curing method for a platinum molded product according to the present invention is more suitable for a form in which the thickness of the platinum molded product is 0.2 to 1.0 mm (0.2 mm to 1.0 mm). Even if the platinum molded product is thin, the strength can be maintained.

In the method for surface hardening a platinum molded product according to the present invention, it is preferable that the method further includes a step of nitriding a partial region or the entire region of the surface of the coating layer. The surface of the platinum molded product can be made harder. In addition, oxide formation can be prevented, and a product with higher purity can be obtained in the low-temperature synthesis method.

In the method for curing a surface of a platinum molded product according to the present invention, the coating solution preferably further contains a platinum compound. The coating layer can be an alloy of either iridium or ruthenium or both and platinum, and the adhesion between the coating layer and the platinum molded product can be further enhanced.

In the method for hardening a surface of a platinum molded article according to the present invention, it is preferable that the coating liquid further contains an alcohol. Since thermal decomposition becomes a reducing atmosphere and oxygen can be removed, generation of oxides can be prevented. Further, since iridium, ruthenium, or an alloy containing at least one of iridium or ruthenium having high corrosion resistance can be precipitated more stably, corrosion can be minimized when used in a high-temperature reducing atmosphere.

In the method for hardening a surface of a platinum molded product according to the present invention, the platinum molded product is an inner cylinder of a pressure vessel, and the application step is performed by applying the application to one or both of the inner surface and the outer surface of the inner cylinder. A mode in which a liquid is applied to form the coating layer is included. Since the self-weight deformation resistance is obtained, the handleability of the inner cylinder alone is improved, and the inner cylinder can be easily attached to the pressure vessel body. In addition, in the low temperature synthesis method, platinum grain growth and intergranular corrosion can be prevented.

In the method for surface hardening a platinum molded product according to the present invention, the platinum molded product is an inner cylinder of a pressure vessel, and further includes an installation process of installing the inner cylinder in the main body of the pressure vessel, the installation process The coating step and the thermal decomposition step are included, and the coating step applies the coating liquid to the inner surface of the inner cylinder to form the coating layer, and the thermal decomposition step includes the coating step. Including a form in which the layer is pyrolyzed in a flame of a gas burner to form the covering layer. The inner surface of the inner cylinder can be hardened without special equipment such as a large heating furnace while being installed in the main body of the pressure vessel.

In the method for hardening a surface of a platinum molded product according to the present invention, the platinum molded product is a shelf for attaching a seed crystal housed in a main body of a pressure vessel, and the coating step is performed on the entire surface of the shelf. The form which forms the said application layer by apply | coating is included. Impurities can be reduced in the growth of single crystals by the low-temperature synthesis method.

In the surface hardening method for a platinum molded product according to the present invention, the platinum molded product is a flange provided at an opening of a pressure vessel, and the coating step is performed on the surface of at least a portion to be a seal portion of the flange. The form which apply | coats a coating liquid and forms the said coating layer is included. The surface hardness of the flange can be increased. Further, the surface of the flange can be hardened without special equipment such as a large heating furnace while being installed in the main body of the pressure vessel.

In the surface hardening method for a platinum molded product according to the present invention, the platinum molded product is a crucible, and the coating step is performed by applying the coating liquid to either or both of the inner surface and the outer surface of the crucible. The form which forms the said application layer is included. Even if the crucible is thin, the handleability can be improved. Further, durability in a reducing atmosphere is improved.

The platinum molded product having a cured surface according to the present invention is characterized in that a coating layer made of iridium, ruthenium, or an alloy containing at least one of iridium or ruthenium is provided on the surface of the platinum molded product.

In the platinum molded product having a cured surface according to the present invention, the surface of the platinum molded product is either the inner surface or the outer surface of the inner tube of the pressure vessel, or both, or a seed crystal accommodated in the main body of the pressure vessel. It includes a form that is the entire surface of the mounting shelf, the surface of at least the portion of the flange provided at the opening of the pressure vessel, or the inner surface or the outer surface of the crucible, or both.

The platinum molded product having a cured surface according to the present invention includes a form in which the thickness of the platinum molded product is 0.2 to 1.0 mm. Even if the molded product is thin, it can maintain strength and has resistance to self-weight deformation.

In the platinum molded product having a cured surface according to the present invention, the coating layer preferably has a thickness of 1 to 30 μm. The surface of the platinum molding can be coated to improve chemical stability and physical strength.

In the platinum molded product whose surface is cured according to the present invention, it is preferable that the platinum element of the platinum molded product and the metal element contained in the coating layer are diffused. Adhesion between the platinum molded product and the coating layer is improved, and chemical stability and physical strength can be further improved.

In the platinum molded product having a cured surface according to the present invention, nitriding treatment of an alloy containing at least one kind of iridium, ruthenium, iridium or ruthenium on at least the surface side of the coating layer in a partial region or the entire region of the coating layer. A layer is preferred. The surface of the platinum molded product can be made harder. In addition, oxide formation can be prevented, and a product with higher purity can be obtained in the low-temperature synthesis method.

In the platinum molded product having a cured surface according to the present invention, the thickness of the nitriding layer is preferably 1 to 30 μm. The surface of the platinum molded product can be made harder.

The present invention is excellent in its own weight deformation resistance even if it is thin, is not easily deformed, is easy to handle, has corrosion resistance and durability in a high temperature and high pressure state, and grows platinum particles in a reducing atmosphere. It is possible to provide a platinum molded article having a cured surface capable of preventing intergranular corrosion and a method for curing the surface.

It is a schematic diagram which shows one form of the cross-sectional structure of the platinum molded product which concerns on this embodiment. It is sectional drawing which shows an example of the pressure vessel which has a shelf. It is sectional drawing which shows an example of the pressure vessel which has an inner cylinder container. It is sectional drawing which shows an example of a large sized pressure vessel. It is the elements on larger scale which show the seal part of the pressure vessel shown in FIG. 4, (a) is a section fragmentary enlarged view which shows one form of a flange and a gasket, (b) is a top view which shows one form of a gasket. is there.

Hereinafter, the present invention will be described in detail with reference to embodiments, but the present invention is not construed as being limited to these descriptions. As long as the effect of the present invention is exhibited, the embodiment may be variously modified.

FIG. 1 is a schematic diagram showing an embodiment of a cross-sectional structure of a platinum molded product according to this embodiment. The platinum molded product 100 having a hardened surface according to this embodiment is provided with a coating layer 30 made of iridium, ruthenium, or an alloy containing at least one of iridium or ruthenium on the surface of the platinum molded product 20.

The type of the platinum molded product 20 is not particularly limited. For example, a seed crystal mounting shelf (baffle / saddle / crystal mounting) housed in the inner body of the pressure vessel or the main body of the pressure vessel (hereinafter referred to as a shelf). And a flange and a crucible provided at the opening of the pressure vessel. Here, the inner cylinder of the pressure vessel forms a sealed space by itself, is accommodated in the main body of the pressure vessel and is used without being joined to the pressure vessel (hereinafter referred to as an inner cylinder container) and pressure. It includes a lining-type inner cylinder (hereinafter referred to as an inner cylinder) that is housed in a container body and used in close contact with or adhered to the inner surface of the pressure vessel body.

The thickness of the platinum molded product 20 is preferably 0.2 to 1.0 mm. More preferably, it is 0.3 to 0.7 mm. If it is less than 0.2 mm, it may be inferior to physical strength and resistance to self-deformation. If the thickness exceeds 1.0 mm, it is difficult to reduce the price of the molded product by making the platinum molded product thinner and reducing the amount of platinum used. In addition, the thickness of the platinum molded product 20 may be uniform as a whole, or the thickness may be partially changed. The form in which the thickness is partially changed is, for example, a form in which the inner cylinder is reinforced by making the thickness of the flange and the thickness of the bottom thicker than the thickness of the cylinder. At this time, it is preferable that the thickness of the thinnest part (for example, the thickness of the side wall part or the bottom part of the cylinder) is 0.2 to 1.0 mm.

The covering layer 30 is made of iridium, ruthenium, or an alloy containing at least one of iridium or ruthenium. An alloy containing iridium, ruthenium, or at least one of iridium or ruthenium has a property of hardly causing grain growth in a reducing atmosphere. Moreover, since those melting | fusing point is 2000 degreeC or more, it is chemically and physically stable on about 1000 degreeC use conditions. As described above, the platinum molded product 100 with the surface cured according to the present embodiment is exposed to iridium, ruthenium, or an alloy containing at least one of iridium or ruthenium on the surface, so that chemical stability in a reducing atmosphere is achieved. Can be improved. Examples of alloys containing iridium (hereinafter referred to as iridium alloys) include iridium-ruthenium alloys, iridium-platinum alloys, iridium-rhodium alloys, iridium-gold alloys, and iridium-rhenium alloys. Examples of the alloy containing ruthenium (hereinafter referred to as a ruthenium alloy) include a ruthenium-iridium alloy, a ruthenium-platinum alloy, a ruthenium-rhodium alloy, a ruthenium-gold alloy, and a ruthenium-rhenium alloy. Among these, an iridium-platinum alloy or ruthenium-platinum alloy, which is an alloy with platinum, is preferable in that the adhesion to the platinum molded product 20 is further improved and the physical strength and the chemical stability are further improved. In the alloy of iridium or ruthenium and platinum, the platinum content is preferably 10 to 70% by mass, more preferably 15 to 60% by mass. If the platinum content in the alloy is less than 10% by mass, the desired effect may not be obtained. When it exceeds 70 mass%, physical strength and corrosion resistance in a reducing atmosphere may be insufficient. In particular, sufficient hardness may not be obtained and the intended purpose may not be achieved. Moreover, when using by a low-temperature synthesis method, it is preferable that the coating layer 30 does not contain the oxide of iridium or ruthenium. A reaction product with higher purity can be obtained.

Whether the metal contained in the coating layer 30 is iridium, ruthenium, or an alloy containing at least one of iridium or ruthenium can be appropriately selected according to the conditions and purpose of use. In addition, an alloy is not limited to the alloy which consists of 2 types of illustrated metals, As long as it alloyes, it can be set as the alloy which consists of 3 or more types of metals. The alloys composed of three or more metals include, for example, ruthenium-platinum-rhodium alloy, iridium-platinum-rhodium alloy, iridium-ruthenium-rhodium alloy, iridium-platinum-rhenium alloy, ruthenium-platinum-rhenium alloy, iridium-ruthenium. A rhenium alloy, iridium-ruthenium-rhodium-platinum.

In the platinum molded product 100 having a cured surface according to the present embodiment, it is preferable that the platinum element of the platinum molded product 20 and the metal elements such as iridium and ruthenium contained in the coating layer 30 are diffused. The platinum of the platinum molded product 20 and the coating layer 30 of iridium, ruthenium, or an alloy containing at least one of iridium or ruthenium are diffused so that the platinum molded product 20 and the coating layer 30 are integrated to improve adhesion. , Physical strength and chemical stability can be further improved. The diffusion state includes, for example, a state in which platinum element diffuses from the platinum molded product 20 into the coating layer 30, a state in which a metal element diffuses from the coating layer 30 into the platinum molded product 20, and a platinum element from the platinum molded product 20 into the coating layer 30. It is an interdiffusion state in which the metal element diffuses and the metal element diffuses from the coating layer 30 into the platinum molded product 20. As described above, the platinum molded article 100 having a hardened surface according to the present embodiment forms a coating layer made of iridium, ruthenium, or an alloy containing at least one kind of iridium or ruthenium after molding platinum having good workability. Then, by diffusing the platinum element of the platinum molded product 20 and the metal element of the coating layer 30, the interface between the platinum molded product 20 and the coating layer 30 is alloyed. In addition, physical strength and chemical stability can be increased. Therefore, it can respond to the platinum molded product 20 of various shapes.

The covering layer 30 may be formed of only one layer, or may be formed of two or more layers. In the case of forming with two or more layers, the configuration of each layer can be changed. When the coating layer 30 is formed of two or more layers, the first coating layer adjacent to the platinum molded product 20 is preferably a layer made of an alloy of platinum and at least one kind of iridium or ruthenium. When the first coating layer and the second coating layer are sequentially provided on the surface of the platinum molded product 20, for example, the first coating layer is made of iridium or an alloy of ruthenium and platinum, and the second coating layer is made of iridium or ruthenium. And rhodium alloy. Of course, the second coating layer may contain a third metal in addition to iridium and ruthenium, or iridium and ruthenium. Note that whether the structure of each layer is iridium, ruthenium, or an alloy containing at least one of iridium or ruthenium can be selected as appropriate according to the use conditions and purpose, and the present embodiment is not limited to this. It is preferable that the metal elements contained in each coating layer formed of two or more layers are diffused in the same manner as the platinum element of the platinum molded product 20 and the metal contained in the coating layer 30. Since each layer is united and alloyed by diffusion, adhesion is improved, and physical strength and chemical stability can be enhanced.

The thickness of the coating layer 30 is preferably 1 to 30 μm. More preferably, it is 3 to 10 μm. If it is less than 1 μm, physical strength and corrosion resistance in a reducing atmosphere may be insufficient. In some cases, the coating layer 30 may be buried by diffusion of the platinum molded product 20 with the platinum element. If it exceeds 30 μm, the coating layer 30 is likely to peel off depending on handling conditions such as rapid heating and quenching due to the difference in thermal expansion coefficient between the platinum element of the platinum molded product 20 and the metal contained in the coating layer 30. In addition, the amount of metal used such as iridium and ruthenium increases, which is not economically preferable. When the covering layer 30 is formed of two or more layers, the total thickness of all the covering layers is within the above range. Moreover, thickness can be changed for every layer.

An alloy containing at least one kind of iridium, ruthenium, or iridium or ruthenium has a characteristic of absorbing oxygen, albeit slightly. Therefore, in the case of being used for a reaction in a reducing atmosphere such as a low-temperature synthesis method, there is an effect that the reducing atmosphere can be maintained.

In the platinum molded product 100 having a hardened surface according to the present embodiment, at least a surface side of the coating layer 30 in a part or all of the coating layer 30 includes iridium, ruthenium, or at least one kind of iridium or ruthenium. The nitriding layer (not shown) is preferable. The surface of the platinum molded product 100 can be further cured. In addition, by forming the surface of the coating layer 30 as a nitriding layer, it is possible to prevent oxides from being formed on the surface of the coating layer 20, so that a reaction such as a low-temperature synthesis method is used as a reaction in which oxygen becomes an impurity. It is suitable for use.

In the case where the platinum molded product 20 is a flange provided at the opening of the pressure vessel, when a partial region of the coating layer 30 is a nitriding layer, for example, it becomes a seal portion that requires particularly physical strength. Only the portion is a nitriding layer. In the case where the platinum molded product 20 is a crucible, when a partial region of the coating layer 30 is a nitriding layer, for example, a part of the inner surface that requires corrosion resistance, and a part in contact with a chemical used for the reaction can be in contact. Only the portion is a nitriding layer.

The nitriding layer contains iridium, ruthenium, or an alloy nitride containing at least one of iridium or ruthenium contained in the coating layer 30. The nitride content of the nitriding layer has a distribution in which the surface is the largest and gradually decreases toward the inside of the substrate. The thickness of the nitriding layer is preferably 1 to 30 μm. More preferably, it is 1 to 10 μm. If it is less than 1 μm, the effect of curing the surface may be insufficient. If it exceeds 30 μm, the surface of the nitriding layer becomes brittle, the surface becomes brittle due to the occurrence of cracks due to residual stress inside the nitriding layer, and peeling may occur when pressure is applied. In addition, since the time required for the nitriding treatment becomes long, it is not economically preferable.

The platinum molding surface hardening method according to the present embodiment includes a coating step in which a coating liquid containing one or both of an iridium salt and a ruthenium salt is applied to the surface of the platinum molding 20 to form a coating layer. And a thermal decomposition step of thermally decomposing the coating layer in a nitrogen gas atmosphere or flame to form the coating layer 30 made of iridium, ruthenium, or an alloy containing at least one kind of iridium or ruthenium.

The platinum molded product 20 can be obtained by a generally known method such as a casting method, a forging method, press molding, welding, or the like. Therefore, the method for molding the platinum molded product 20 is not particularly limited in the present embodiment. The thickness of the platinum molded product 20 is preferably 0.2 to 1.0 mm.

In the coating step, a coating solution containing either or both of an iridium salt and a ruthenium salt is coated on the surface of the platinum molded product 20 and dried to form a coating layer. The coating solution is not particularly limited in the present embodiment as long as it can form the coating layer 30 by depositing iridium, ruthenium, or an alloy containing at least one of iridium or ruthenium by thermal decomposition performed later. The coating solution is, for example, a solution in which an iridium salt or a ruthenium salt is mixed with alcohol as a solvent. Examples of the iridium salt include iridium chloride, iridium nitrate, chloroiridic acid, and iridium butoxide. Examples of the ruthenium salt include ruthenium chloride, ruthenium nitrate, ruthenium chloride, and ruthenium butoxide. Among these, the iridium salt is preferably iridium chloride in that it can efficiently precipitate iridium, ruthenium, or an alloy containing at least one of iridium or ruthenium by thermal decomposition. The ruthenium salt is preferably ruthenium chloride because it is easily available and relatively inexpensive.

The coating liquid may further contain a metal compound that forms an alloy with iridium or ruthenium. Examples of metal compounds forming alloys with iridium or ruthenium include platinum compounds such as chloroplatinic acid and dinitrodiammine platinum, rhodium compounds such as rhodium chloride and rhodium nitrate, gold compounds such as chloroauric acid, gold chloride and gold cyanide. Compounds, rhenium compounds such as rhenium chloride and rhenium nitrate. Of these, chloroplatinic acid, dinitrodiammine platinum and the like are preferably used as the platinum compound, and chloroplatinic acid is particularly preferred for combination with iridium salts and ruthenium salts. Since an alloy of iridium or ruthenium and platinum is formed and adhesion to the platinum molded article is increased, physical strength and corrosion resistance in a reducing atmosphere are further improved.

The coating solution preferably contains alcohol as a solvent. Here, alcohol is a solvent and an organic reducing agent. Examples of the alcohol include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, isobutanol, tert-butanol, and 1-pentanol. The coating solution may further contain an organic reducing agent other than alcohol such as turpentine oil. The present embodiment is not limited to the method of applying the coating liquid and the method of drying.

In the thermal decomposition step, the coating layer is thermally decomposed in a nitrogen gas atmosphere or in a flame, whereby one or both of iridium salt and ruthenium salt and iridium or ruthenium and alloy contained in the coating layer obtained in the coating step are alloyed. The coating layer 30 is formed by precipitating a metal compound that forms iridium, ruthenium, or an alloy containing at least one of iridium or ruthenium. When iridium and ruthenium are thermally decomposed in an atmosphere containing oxygen, an oxide is formed. Therefore, the metal can be precipitated by thermally decomposing the coating layer in a nitrogen gas atmosphere or in a flame. Pyrolysis is preferably performed in a nitrogen atmosphere using a heating furnace capable of supplying nitrogen gas. However, at the work site, for example, if the platinum molding is large enough not to enter the heating furnace, if the platinum molding is attached to another part in a state where it is difficult to attach and detach, the whole cannot be heated, It is assumed that the equipment cannot be prepared. In such a case, thermal decomposition can be performed in a flame using a gas burner in an atmospheric atmosphere. Here, since oxygen in the air is used for combustion, the surface of the platinum molded product is substantially in a nitrogen atmosphere, and can deposit iridium, ruthenium, or an alloy containing at least one of iridium or ruthenium as a metal. . Furthermore, it is more preferable to perform thermal decomposition while supplying nitrogen gas around the torch of the gas burner in that the nitrogen atmosphere can be further increased. Moreover, by making the coating liquid contain alcohol, a reducing atmosphere can be obtained and generation of oxides can be prevented.

The thickness of the coating layer 30 is preferably 1 to 30 μm. More preferably, it is 1 to 10 μm. It is preferable to repeat the coating step and the thermal decomposition step a plurality of times until the thickness is reached. A uniform coating layer with few pores can be obtained, and the surface of the platinum molded product can be more reliably covered with iridium, ruthenium, or an alloy containing at least one of iridium or ruthenium. The coating amount per coating step is preferably 0.05 to 1 μm. More preferably, it is 0.10 to 0.5 μm.

When repeating the coating step and the thermal decomposition step a plurality of times, the components of the coating solution may be the same in all coating steps, or two or more types of coating solutions may be used. When two or more kinds of coating solutions are used, the coating solution used in the first coating step may contain a platinum compound such as chloroplatinic acid in addition to one or both of the iridium salt and the ruthenium salt. preferable. For example, when the coating process and the thermal decomposition process are repeated 15 times to make the coating layer 5 μm, in the first 5 coating processes, the coating solution is applied as an alcohol solution of iridium chloride and chloroplatinic acid once. In the next 10 coating steps, the coating solution is an alcohol solution of iridium chloride and ruthenium chloride, and the coating amount per coating step is 0.4 μm. . Thus, a two-layer coating layer comprising a first coating layer made of iridium-platinum alloy formed on the surface of the platinum molded product 20 and a second coating layer made of iridium formed on the first coating layer. 30 can be formed. Since the coating layer 30 has improved adhesion to the platinum molded product 20, physical strength and corrosion resistance in a reducing atmosphere are further improved. Furthermore, since the coefficient of thermal expansion (linear expansion coefficient) occurs in stages, the coating layer itself is less likely to break during heating and cooling, and is difficult to peel off.

It is preferable that diffusion is performed between the platinum element of the platinum molded product 20 and the metal element contained in the coating layer 30. The diffusion may be performed simultaneously with the thermal decomposition process by heating in the thermal decomposition step, but after the thermal decomposition step, further heating is performed to diffuse the platinum element of the platinum molded product 20 and the metal element contained in the coating layer 30. At the same time, it is preferable to provide a stabilization step for removing strain in the coating layer. In particular, when two or more kinds of metals are contained as the metal contained in the coating layer 30, a metal containing at least one kind of iridium or ruthenium is pre-alloyed to form a coating layer in the pyrolysis step, By further heating in the stabilization step, diffusion can be performed more efficiently. Further, when the coating layer is formed by repeating the coating step and the thermal decomposition step a plurality of times, in the thermal decomposition step, a metal containing at least one kind of iridium or ruthenium is alloyed in the thermal decomposition step, and the stabilization step is performed. Diffusion treatment can be performed between the metals contained in the adjacent coating layers and between the platinum element of the platinum molded product and the metal contained in the first coating layer adjacent to the platinum molded product.

In the pyrolysis step and the stabilization step, the heating conditions are not particularly limited. When the stabilization process is not performed, for example, in the thermal decomposition process, the heating temperature is set to 700 to 1000 ° C. and the heating time is set to 1 to 2 hours, so that the thermal decomposition process and the diffusion process can be performed simultaneously. Further, when the stabilization process is performed, for example, in the thermal decomposition process, the heating temperature is set to 500 to 600 ° C., the processing time is set to 5 to 15 minutes, and the thermal decomposition process is performed. In the stabilization process, the heating temperature is set to 700 The diffusion treatment is performed at a temperature of ˜1000 ° C. and a heating time of 1 to 2 hours. In the stabilization step, the diffusion treatment can be performed in an inert atmosphere such as nitrogen or argon or in an oxygen-containing atmosphere such as air. More preferably, it is in an inert atmosphere such as nitrogen or argon. By carrying out in an inert atmosphere, oxides are not formed on the surface, and crystals with higher purity can be obtained in the low-temperature synthesis method. In this embodiment, since the alloy is preliminarily alloyed in the thermal decomposition step, the oxide can be diffused almost without being formed even in an oxidizing atmosphere such as an air atmosphere.

It is preferable that the method for hardening a surface of a platinum molded article according to the present embodiment further includes a step of nitriding a partial region or the entire region of the surface of the coating layer 30. The nitriding treatment can be performed by heating in a gas containing nitrogen or a nitrogen compound. The gas containing nitrogen or a nitrogen compound is not particularly limited, and examples thereof include nitrogen gas, ammonia gas, and nitrogen-hydrogen mixed gas. The heating temperature and the heating time are not particularly limited, and it is preferable to select conditions under which the thickness of the nitriding layer is in the range of 1 to 30 μm, for example. By nitriding, the surface hardness of the platinum molded product can be further increased. Furthermore, since the oxide can be removed, the purity of the generated crystal can be improved in the low-temperature synthesis method. A method of nitriding a part of the region is not particularly limited, and for example, there is a method of masking a portion where nitriding is not performed.

FIG. 2 is a cross-sectional view showing an example of a pressure vessel having a shelf. A pressure vessel 119 shown in FIG. 2 is used as a single crystal growth vessel. The basic configuration of the pressure vessel 119 is as follows. The pressure vessel 119 has a main body 1 and a lid 2. The main body 1 and the lid 2 are made of a heat-resistant alloy such as low alloy steel or nickel chrome alloy, for example. The main body 1 is heated by a heater 4 disposed on the outer periphery thereof. A lower inner cylinder 105 is installed inside the main body 1. The lower inner cylinder 105 is formed with a flange 105a (hereinafter also referred to as a lower flange). In addition, an upper inner cylinder 106 is installed in the inside of the lid 2 in the same manner as the main body 1. The upper inner cylinder 106 is formed with a flange 106a (hereinafter also referred to as an upper flange). The lower inner cylinder 105 and the upper inner cylinder 106 are lining type inner cylinders. The main body 1 has a bottomed cylindrical shape with one end opened, and a lower flange 105a projecting in the centrifugal direction is provided on the outer peripheral edge of the opening. The pressure vessel 119 is structured to be sealed by being fixed with a fixing tool 3 such as a nut or a clamp through a gasket 7 between the upper flange 106a and the lower flange 105a. Therefore, since a large pressure is applied to the flange, it is necessary to have a sufficient pressure resistance. When the pressure vessel is sealed, the upper flange 106a, the gasket 7, and the lower flange 105a are in contact with each other by a line or a surface to form a seal portion (hereinafter, the contact portion is referred to as a seal portion). In particular, a high surface hardness is required for the seal portion. The lower inner cylinder 105 and the upper inner cylinder 106 are formed of a metal having heat and corrosion resistance such as platinum. The gasket 7 is formed of a metal having heat and corrosion resistance, such as a nickel-based alloy or a platinum group metal, and more preferably formed of a material having lower hardness than the upper flange 106a and the lower flange 105a.

A shelf 108 is accommodated in the main body 1 of the pressure vessel 119 shown in FIG. The shelf 108 is a platinum frame. The shelf 108 has a seed crystal gantry 10 at the upper part, a raw material 11 at the lower part, and a convection control plate 9 between the seed crystal gantry 10 and the raw material 11, and is filled with a solvent (not shown). It is installed in the cylinder 105 and the upper inner cylinder 106. The single crystal is grown in the lower inner cylinder 105 and the upper inner cylinder 106. Accordingly, the lower inner cylinder 105 and the upper inner cylinder 106 are required to have high corrosion resistance, and thus need to be molded with platinum.

In the surface hardening method for a platinum molded product according to this embodiment, the platinum molded product is preferably the lower inner cylinder 105 and the upper inner cylinder 106 of the pressure vessel 119. The size of the lower inner cylinder 105 varies depending on the size of the pressure vessel. For example, it is a medium-sized pressure vessel and has an inner diameter of 20 to 70 mm and a capacity of 0.1 to 8 l. A large pressure vessel with an inner diameter of 70 to 150 mm and a capacity of 8 to 50 l.

The surface treatment of the lower inner cylinder 105 can be performed either before installation on the main body 1 of the pressure vessel 119 or after installation on the main body 1 of the pressure vessel 119. When the surface treatment of the lower inner cylinder 105 is performed before installation on the main body 1, the surface on which the coating layer is provided can be either the inner surface or the outer surface of the lower inner cylinder 105, or both, The inner cylinder 105 can be appropriately selected according to various conditions such as dimensions, applications, and reaction conditions. Even if the thickness of the lower inner cylinder 105 is reduced to, for example, 0.2 to 1.0 mm, the attachment and detachment work into the main body 1 is facilitated. Even if the thickness of the lower inner cylinder 105 is reduced, resistance to self-weight deformation can be imparted. In addition, the lower inner cylinder 105 can be easily handled, and the attachment and removal work of the pressure vessel 119 in the main body 1 is facilitated. When used in the low-temperature synthesis method, by forming a coating layer on at least the inner surface of the lower inner cylinder 105, it is possible to prevent grain growth and intergranular corrosion in a high-temperature reducing atmosphere, and a reaction with higher purity. A product can be obtained. Furthermore, by nitriding the coating layer, the physical strength can be further improved, and the purity of the reaction product obtained by the low temperature synthesis method can be further increased.

When the surface treatment of the lower inner cylinder 105 is performed after the pressure vessel 119 is installed on the main body 1, the surface on which the coating layer is provided can be the inner surface of the lower inner cylinder 105. In this case, the pyrolysis step is preferably pyrolyzed in a flame of a gas burner to form the coating layer as a coating layer. By using a flame of a gas burner in the pyrolysis process, the surface treatment can be performed with the gas burner being installed in the main body 1 of the pressure vessel 119, and avoiding the possibility of deformation or breakage when the lower inner cylinder 105 is removed. be able to. In addition, the pressure vessel having the platinum lower inner cylinder 105 already installed at the work site can be cured on the inner surface of the lower inner cylinder 105 without being moved from the work site. It can be set as the pressure vessel corresponding to. Furthermore, the surface of the coating layer is further nitrided by adding nitrogen or hydrogen gas to which this nitrogen or hydrogen is added and heated from the outside, thereby further improving the physical strength, and by using a low-temperature synthesis method. The purity of the reaction product can be further increased.

Moreover, in the platinum molded product having a hardened surface according to the present embodiment, the surface of the platinum molded product is preferably the upper inner cylinder 106 disposed on the lid 2 of the pressure vessel 119. The production of impurities can be further suppressed, and a reaction product with high purity can be obtained.

In the surface hardening method for a platinum molded product according to the present embodiment, the platinum molded product is preferably a shelf 108 accommodated in the main body 1 of the pressure vessel 119. The material thickness of the shelf 108 can be reduced to, for example, 0.2 to 1.0 mm. Even if the shelf 108 is made thin, it can be prevented from being deformed by its own weight. Further, the shelf 108 can be easily handled, and the operation of storing and taking out the pressure vessel 119 into the main body 1 is facilitated. Further, the shelf 108 can be integrally formed of platinum. The dimensions of the shelf 108 vary depending on the size of the pressure vessel. For example, the shelf 108 is a medium-sized pressure vessel having an inner diameter of 20 to 70 mm and a height of 300 to 2000 mm. A large pressure vessel with an inner diameter of 70 to 150 mm and a height of 2000 to 3000 mm.

The surface on which the coating layer 30 is provided is preferably the entire surface of the shelf 108 accommodated in the main body 1 of the pressure vessel 119. By forming a coating layer on the entire surface of the constituent parts of the shelf 108, when used in the low temperature synthesis method, grain growth and intergranular corrosion in a high temperature reducing atmosphere can be prevented, and a reaction with higher purity can be achieved. A product can be obtained. Furthermore, by nitriding the coating layer, the purity of the reaction product can be further improved and the physical strength can be increased. When used in the low temperature synthesis method, it is naturally preferable to provide a coating layer on the inner surfaces of the lower inner cylinder 105 and the upper inner cylinder 106.

FIG. 3 is a cross-sectional view showing an example of a pressure vessel having an inner cylinder vessel. The pressure vessel 19 shown in FIG. 3 has the same basic configuration as the pressure vessel shown in FIG. An inner cylinder container 8 is accommodated in the main body 1 of the pressure container 19 shown in FIG. The inner cylinder container 8 is a sealable cylindrical container made of platinum. A bellows 12 for pressure adjustment is attached to the upper portion of the inner cylinder container 8 in a sealed state. A shelf 108 and a solvent (not shown) illustrated in FIG. 2 are accommodated inside the inner cylinder container 8. The single crystal is grown in the inner cylinder container 8. Therefore, in the pressure vessel 19 shown in FIG. 3, the lower anticorrosion lining 5 and the upper anticorrosion lining 6 do not directly touch the treatment liquid, and therefore do not require high corrosion resistance as required for the inner cylinder. Although platinum is particularly preferable, the present invention is not limited to this. For example, nickel-based alloys such as the trade names “HASTELLOY” and “INCONEL”, titanium, titanium alloys, tantalum, and tantalum alloys can be used. The size of the inner cylinder container 8 varies depending on the size of the pressure container, but is, for example, a medium-sized pressure container having an inner diameter of 20 to 70 mm and a capacity of 0.1 to 8 l. A large pressure vessel with an inner diameter of 70 to 150 mm and a capacity of 8 to 50 l.

In the surface hardening method for a platinum molded product according to this embodiment, the platinum molded product is preferably the inner cylinder container 8 of the pressure vessel 19. The thickness of the inner cylinder container 8 can be reduced to, for example, 0.2 to 1.0 mm. Even if the thickness of the inner cylinder container 8 is reduced, it can be prevented from being deformed by its own weight. Moreover, it becomes easy to handle the inner cylinder container alone, and the operation of storing and taking out the pressure container 19 into the main body 1 is facilitated. Furthermore, since the inner cylinder container 8 and the bellows 12 can be integrally formed of platinum, complicated joining between the inner cylinder container 8 and the bellows 12 becomes unnecessary, and the pressure resistance of the inner cylinder container 8 can be further increased. it can.

The surface on which the coating layer 30 is provided can be either one or both of the inner surface and the outer surface of the inner cylinder container 8 of the pressure vessel 19, and depends on various conditions such as the dimensions, applications, reaction conditions, etc. of the inner cylinder container 8 Can be selected as appropriate. When used in the low-temperature synthesis method, by forming a coating layer on at least the inner surface of the inner cylinder container 8, grain growth and intergranular corrosion in a high-temperature reducing atmosphere can be prevented, and a reaction with higher purity can be achieved. A product can be obtained. Furthermore, by nitriding the coating layer, the purity of the reaction product can be further improved and the physical strength can be increased.

In the pressure vessel 19 of FIG. 3, when the lower anticorrosion lining 5 and the upper anticorrosion lining 6 are made of platinum, a coating layer can be formed on the inner surface to harden the surface. As a result, the gasket / flange portion can be simplified and the structure can be simplified.

FIG. 4 is a cross-sectional view showing an example of a large pressure vessel. The pressure vessel 900 shown in FIG. 4 has the same basic configuration as the pressure vessel shown in FIG. In the pressure vessel 900 of FIG. 4, a lower anticorrosion lining 5 is further disposed between the main body 1 and the lower inner cylinder 105, and an upper anticorrosion lining 6 is also disposed between the lid 2 and the upper inner cylinder 106. Yes. The lower anticorrosion lining 5 and the upper anticorrosion lining 6 are made of a nickel-based alloy having excellent pressure resistance, heat resistance and corrosion resistance, such as trade names of Inconel and Hastelloy. The lower anticorrosion lining 5 and the upper anticorrosion lining 6 have a role of preventing the main body 1 from being corroded when the lower inner cylinder 105 and the upper inner cylinder 106 are damaged and a highly corrosive substance flows out. It can be set as the pressure vessel corresponding to high temperature / high pressure conditions. In addition, although the pressure vessel 119 of FIG. 2 is a medium-sized pressure vessel, you may provide anticorrosion lining in them.

Since the large pressure vessel 900 shown in FIG. 4 has a structure in which the lower anticorrosion lining 5 and the lower inner cylinder 105 are arranged on the inner surface of the main body 1, the surface treatment of the lower inner cylinder 105 inevitably increases in size. The inner cylinder itself can be made thinner. As a result, the amount of expensive platinum used can be reduced, and a great economic advantage can be obtained.

FIG. 5 is a partially enlarged cross-sectional view showing a seal portion of the pressure vessel shown in FIG. As described above, since high pressure is applied to the lower flange 105a and the upper flange 106a, high surface hardness is required. Therefore, the platinum molded product surface hardening method according to the present embodiment is suitable for a form in which the platinum molded product 20 is the lower flange 105 a and the upper flange 106 a provided in the opening of the pressure vessel 900.

The lower inner cylinder 105 and the lower flange 105a may be integrally formed of platinum, or the lower flange 105a may be formed as a separate part and the lower inner cylinder 105 and the lower flange 105a may be joined. In the case where the lower flange 105a is formed as a separate part, the present embodiment is not limited to the method of joining the lower inner cylinder 105 and the lower flange 105a. As a method of joining, for example, as shown in FIG. 5, there is a method in which a flange mounting portion T is provided on the opening periphery of the lower inner cylinder 105 and the lower flange 105 a is attached thereon by welding or diffusion joining. Similarly to the lower inner cylinder 105 and the lower flange 105a, the upper inner cylinder 106 and the upper flange 106a may be integrally formed of platinum, or the upper flange 106a is formed as a separate part, and the upper inner cylinder 106 is formed. And the upper flange 106a may be joined.

The surface on which the coating layer is provided is preferably the surface of the portion S that becomes at least a seal portion of the lower flange 105a and the upper flange 106a. Although the coating layer should just be formed in the surface of the part S used as a seal location at least, More preferably, it is a form which coat | covers the whole surface of the side which the upper flange 106a and the lower flange 105a face. By forming it on the entire surface, the durability of the upper flange 106a and the lower flange 105a can be improved. Although the flange of the pressure vessel shown in FIG. 4 has been described with reference to FIG. 5, in this embodiment, the flange as the platinum molded product is connected to the lower flange 105 a attached to the lower inner cylinder 105 shown in FIG. 4. It is not limited, For example, the lower flange 5a and the upper flange 6a which were formed in the lower anticorrosion lining 5 and the upper anticorrosion lining 6 shown in FIG. 3 are included.

In order to prevent deformation of the upper flange 106a and the lower flange 105a in FIG. 4, the upper flange 6a and the lower flange 5a in FIG. 3, the upper flange 106a and the lower flange 105a in FIG. 4, the upper flange 6a and the lower flange 5a in FIG. This surface is preferably harder than the surface of the gasket 7. By forming the coating layer 30 on the surfaces of the upper flange 106a and the lower flange 105a in FIG. 4 and the upper flange 6a and the lower flange 5a in FIG. 3, the surface can be made harder than the gasket 7. In order to make the surfaces of the upper flange 106a and the lower flange 105a in FIG. 4 and the upper flange 6a and the lower flange 5a in FIG. 3 harder, it is preferable to repeat the coating process and the thermal decomposition process twice or more to form a coating layer. . There are few pores, a uniform coating layer can be obtained, and physical strength can be increased. Here, at least the coating solution used in the first coating step is blended with an iridium salt or ruthenium salt and a platinum compound such as chloroplatinic acid to form a coating layer made of an alloy of iridium or ruthenium and platinum. It is preferable to do. The adhesion between the platinum molded product and the coating layer is increased, and the physical strength can be further improved. Furthermore, when calculating | requiring hardness, the surface hardness and physical strength can be raised more by carrying out the nitriding process of the surface of the coating layer 30. FIG.

When the surface of the platinum molded product whose surface is hardened according to the present embodiment is the upper flange 106a and the lower flange 105a in FIG. 4, the upper flange 6a and the lower flange 5a in FIG. 3, JIS Z 2244: 2009 The surface Vickers hardness measured according to the above is preferably 300 Hv to 500 Hv. More preferably, it is 350 Hv to 450 Hv. If it is less than 300 Hv, a large deformation (collapse) may occur due to tightening, and sufficient sealing may not be achieved. In addition, the surface hardness may be lower than that of the gasket, and the flange may be deformed to shorten the life of the pressure vessel. If it exceeds 500 Hv, cracks may occur. Furthermore, it may break.

In the method for surface hardening a platinum molded product according to the present embodiment, the platinum molded product is preferably a crucible. The platinum crucible is used for the purpose of preventing contamination of trace impurities such as single crystal growth of various oxides and melting of optical glass. In this embodiment, the platinum molded product 20 includes a so-called reinforced platinum crucible in which an oxide such as zirconia (ZrO ₂ ) is dispersed. The surface on which the coating layer 30 is provided can be either one or both of the inner surface and the outer surface of the crucible, and can be appropriately selected according to various conditions such as the size of the crucible, application, and reaction conditions. The thickness of the crucible can be reduced to 0.2 to 1.0 mm, for example. Even if the thickness of the crucible is reduced, the crucible can be prevented from being deformed by its own weight. In addition, the crucible can be handled easily. Furthermore, durability in a reducing atmosphere is improved. Furthermore, by nitriding the coating layer 30, the purity of the reaction product can be further improved, and the physical strength can be increased. The dimensions of the crucible are, for example, an inner diameter of 25 to 100 mm, a height of 25 to 150 mm, and a capacity of 0.01 to 2 l. In addition, this embodiment is not restrict | limited to the shape and dimension of a crucible.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not construed as being limited to the examples.

Example 1
As a platinum molded product, an inner cylinder of a bottomed cylindrical pressure vessel having one end opened with platinum having a diameter (inner dimension) of 30 mm, a height of 200 mm, and a thickness of 0.2 mm was formed. Iridium chloride and chloroplatinic acid were mixed at a molar ratio of 80:20, dissolved in butanol, and a solution having a total molar concentration of iridium and platinum of 0.25 mol-Ir + Pt / l was used as a coating solution. The obtained coating solution was applied to the inner surface of the inner cylinder, allowed to stand at 60 ° C. for 10 minutes, and dried to form a coating layer. The coating amount per one time was 20 ml / m ² . When the surface of the coating layer was thermally decomposed by heat treatment using a gas burner flame in the atmosphere, an iridium-platinum alloy film having a thickness of 0.1 μm was obtained. In the thermal decomposition process, heating was performed so that the maximum temperature of the heat-treated surface at the center of the portion exposed to the flame was in the range of 600 to 750 ° C., and the treatment time was 10 minutes. In this example, the flame temperature was measured using a radiation thermometer (model AD-5616, manufactured by A & D). The coating from coating to thermal decomposition was repeated 10 times to form a coating layer made of iridium-platinum alloy having a thickness of 1.0 μm. The surface of the coating layer was further heated by using a gas burner flame in an air atmosphere to carry out a stabilization treatment. In the stabilization step, heating was performed so that the maximum temperature of the heat-treated surface at the center of the portion exposed to the flame was in the range of 750 to 900 ° C., and the treatment time was 20 minutes. The obtained inner cylinder has increased surface hardness and is easy to attach to the pressure vessel body. Further, since the inner surface was coated with an iridium-platinum alloy, it was possible to form an inner cylinder that hardly caused grain growth and intergranular corrosion even when used as a container for the low temperature synthesis method.

(Example 2)
As a platinum molded product, a flange having a diameter of 70 mm and a thickness of 2.0 mm was formed on the outer peripheral edge of the opening of the platinum inner cylinder. Ruthenium chloride and chloroplatinic acid were mixed at a molar ratio of 1: 1, dissolved in butanol, and a solution having a total molar concentration of ruthenium and platinum of 0.5 mol-Ru + Pt / l was used as the first coating solution. . The obtained first coating solution was applied to the surface of the flange facing the flange (upper flange) on the lid side, allowed to stand at 40 ° C. for 15 minutes, and dried to form a coating layer. The coating amount per one time was 20 ml / m ² . When the surface of the coating layer was thermally decomposed by heat treatment using a gas burner flame in an air atmosphere, a 0.2 μm thick ruthenium-platinum alloy film was obtained. In the first pyrolysis step, heating was performed so that the maximum temperature of the heat-treated surface at the center of the portion exposed to the flame was in the range of 550 to 650 ° C., and the treatment time was 30 minutes. From application of the first coating solution to thermal decomposition was repeated 5 times to form a first coating layer made of ruthenium-platinum having a thickness of 1.0 μm. Next, ruthenium chloride and rhodium chloride are blended at a molar ratio of 1: 1, dissolved in butanol, and a solution having a total molar concentration of ruthenium and rhodium of 1.0 mol-Ru + Rh / l is used as the second coating solution. did. The obtained 2nd coating liquid was apply | coated on the 1st coating layer, and it left still for 10 minutes at 60 degreeC, and it was made to dry and the coating layer was formed. The coating amount per one time was 0.5 μm. The surface of the coating layer was heat-treated using a gas burner flame in the air atmosphere and thermally decomposed to obtain a ruthenium-rhodium alloy film having a thickness of 0.5 μm. In the second pyrolysis step, heating was performed so that the maximum temperature of the heat-treated surface at the center of the portion exposed to the flame was in the range of 650 to 750 ° C., and the treatment time was 30 minutes. The application from the second coating solution to thermal decomposition was repeated 20 times to form a second coating layer made of ruthenium-rhodium having a thickness of 10 μm. Furthermore, the stabilization process was performed using an electric furnace with a muffle in an air atmosphere at an atmospheric temperature of 700 ° C. and a processing time of 2 hours. The obtained flange having a hardened surface apparently had a slightly different color tone from platinum, and showed a slightly blackish metallic luster. When the Vickers hardness was measured according to JIS Z 2244: 2009, it was 350 to 380 Hv, and it was confirmed that the surface hardness was sufficient as a flange.

(Example 3)
As a platinum molded product, a crucible having a diameter (inner dimension) of 70 mm, a height of 100 mm, and a thickness of 0.8 mm was molded. Iridium chloride was dissolved in butanol, and a solution having a molar concentration of iridium of 0.5 mol-Ir / l was used as a coating solution. The obtained coating solution was applied to the inner and outer surfaces of the crucible, allowed to stand at 40 to 50 ° C. for 10 minutes, and dried to form a coating layer. The coating amount per one time was 20 ml / m ² . When the surface of the coating layer was subjected to thermal decomposition using a flame of a gas burner while feeding a mixed gas of butane gas and air, a iridium metal film having a thickness of 0.1 μm was obtained. In the pyrolysis step, heating was performed so that the maximum temperature of the heat-treated surface at the center of the portion exposed to the flame was in the range of 800 to 850 ° C., and the treatment time was 20 minutes. The coating liquid coating to thermal decomposition was repeated 10 times to form a coating layer made of iridium metal and having a thickness of 1.0 μm. The surface of the coating layer was further heated in an air atmosphere using a flame of a gas burner to perform a stabilization treatment. In the stabilization process, heating was performed so that the maximum temperature of the heat-treated surface at the center of the portion exposed to the flame was in the range of 850 to 900 ° C., and the treatment time was 40 minutes. The resulting crucible had increased surface hardness and improved handling.

Example 4
In Example 1, iridium chloride and ruthenium chloride were blended in a molar ratio of 80:20, dissolved in butanol, and a solution having a total molar concentration of iridium and ruthenium of 0.5 mol-Ir + Ru / l was applied as a coating solution. Except that, the surface of the inner cylinder of the pressure vessel, which is a platinum molded product, was cured according to Example 1. The inner surface of the obtained inner cylinder was coated with an iridium-ruthenium alloy. The obtained inner cylinder has increased surface hardness and is easy to attach to the pressure vessel body. Moreover, even if it used as a container of the low temperature synthesis method, it was able to be set as the inner cylinder which hardly raise | generates a grain growth and intergranular corrosion. For reference, the Vickers hardness was measured according to JIS Z 2244: 2009 in the same manner as in Example 2, and it was 380 to 400 Hv.

(Example 5)
In Example 2, after the stabilization treatment, the entire surface of the flange surface was nitrided by holding in pure nitrogen gas at 1100 ° C. for 3 hours. The thickness of the nitriding layer was about 5 μm. When the Vickers hardness of the surface of the nitrided layer was measured according to JIS Z 2244: 2009, it was 420 to 450 Hv, and it was confirmed that the surface hardness was improved as compared with the flange obtained in Example 2.

The surface hardening method for a platinum molded product according to the present invention can ensure physical strength even if the platinum molded product is thin, for example, 0.2 to 1.0 mm. In addition, by making the inner surface of the platinum molded article an alloy containing at least one of iridium, ruthenium or iridium or ruthenium, platinum grain growth and intergranular corrosion can be prevented even in a reducing atmosphere such as a thermal synthesis method. It can be prevented and a chemically stable platinum molded article can be obtained. The surface-curing method for a platinum molded product according to the present invention is suitable for curing the inner surface, outer surface, or inner / outer surface of an inner cylinder, a flange, and a crucible of a pressure vessel, for example. Moreover, the surface hardening method of the platinum molded product according to the present invention is suitable for curing the surface of a platinum molded product such as platinum tongs and evaporating dishes.

DESCRIPTION OF SYMBOLS 1 Main body 2 Cover 3 Fixing tool 4 Heater 5 Lower anticorrosion lining 6 Upper anticorrosion lining 5a, 105a Lower flange 6a, 106a Upper flange 7 Gasket 8 Inner cylinder container 8a Inner cylinder container flange 9 Convection control plate 10 Seed crystal mount 11 Raw material 12 Bellows 19, 119, 900 Pressure vessel 20 Platinum molded product 30 Cover layer 100 Platinum molded product 105 whose surface is cured Lower inner cylinder 106 Upper inner cylinder 100 Platinum molded product 108 Shelf (baffle / saddle / crystal mounting)

Claims (17)

An application step of applying a coating liquid containing either or both of an iridium salt and a ruthenium salt to the surface of the platinum molded product to form a coating layer;
A thermal decomposition step of thermally decomposing the coating layer in a nitrogen gas atmosphere or in a flame to form the coating layer as a coating layer made of iridium, ruthenium, or an alloy containing at least one of iridium or ruthenium;
A surface-curing method for a platinum molded product, comprising: 2. The method for hardening a surface of a platinum molded article according to claim 1, wherein the platinum molded article has a thickness of 0.2 to 1.0 mm. The method for hardening a surface of a platinum molded article according to claim 1 or 2, further comprising a step of nitriding a partial area or the entire area of the surface of the coating layer. 4. The method for curing a surface of a platinum molded article according to claim 1, wherein the coating solution further contains a platinum compound. The method for curing a surface of a platinum molded article according to any one of claims 1 to 4, wherein the coating solution further contains an alcohol. The platinum molded product is an inner cylinder of a pressure vessel,
6. The coating process according to claim 1, wherein in the coating step, the coating layer is formed by coating the coating liquid on either or both of the inner surface and the outer surface of the inner cylinder. A method for curing a surface of a platinum molded article as described. The platinum molded product is an inner cylinder of a pressure vessel,
Furthermore, it has an installation step of installing the inner cylinder in the main body of the pressure vessel,
After the installation step, the coating step and the thermal decomposition step,
The coating step forms the coating layer by coating the coating liquid on the inner surface of the inner cylinder,
The surface hardening of a platinum molded article according to any one of claims 1 to 5, wherein in the pyrolysis step, the coating layer is formed by pyrolyzing the coating layer in a flame of a gas burner. Method. The platinum molded product is a seed crystal mounting shelf accommodated in the body of the pressure vessel,
The method for hardening a surface of a platinum molded article according to any one of claims 1 to 5, wherein, in the coating step, the coating layer is formed by coating the coating liquid on the entire surface of the shelf. The platinum molded product is a flange provided at the opening of the pressure vessel,
The platinum molding according to any one of claims 1 to 5, wherein, in the coating step, the coating layer is formed by coating the coating liquid on a surface of at least a portion to be a seal portion of the flange. Surface curing method for objects. The platinum molded product is a crucible,
6. The coating process according to claim 1, wherein the coating step forms the coating layer by coating the coating solution on one or both of the inner surface and the outer surface of the crucible. Surface hardening method for platinum moldings. A platinum molded article having a cured surface, wherein a coating layer made of iridium, ruthenium, or an alloy containing at least one of iridium or ruthenium is provided on the surface of the platinum molded article. The surface of the platinum molded article is either one or both of the inner surface and the outer surface of the inner tube of the pressure vessel, the entire surface of the shelf for attaching a seed crystal accommodated in the main body of the pressure vessel, and the opening of the pressure vessel. The surface-cured platinum molded product according to claim 11, which is at least one of or both of a surface of a portion to be a sealing portion of a provided flange, an inner surface or an outer surface of a crucible. The platinum molded product with a hardened surface according to claim 11 or 12, wherein the platinum molded product has a thickness of 0.2 to 1.0 mm. The platinum molded product with a hardened surface according to any one of claims 11 to 13, wherein the coating layer has a thickness of 1 to 30 µm. 15. The platinum molded product with a hardened surface according to claim 11, wherein the platinum element of the platinum molded product and the metal element contained in the coating layer are diffused. The nitriding layer of an alloy containing at least one kind of iridium, ruthenium, or iridium or ruthenium in at least the surface side of the coating layer in a partial region or the entire region of the coating layer. A platinum molded article having the surface according to any one of which is cured. The surface-cured platinum molded product according to claim 16, wherein the nitriding layer has a thickness of 1 to 30 µm.

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