JP2006037238A - Method for producing spherical particles for thermal spraying - Google Patents

Abstract

A granulated powder obtained by granulating an oxide containing a rare earth element (including yttrium) having a Fischer diameter of 0.6 μm or less is fired at 1,200 to 1,800 ° C. A method for producing spherical particles for thermal spraying.
[Effect] According to the spherical particle for thermal spraying of the present invention, it is possible to provide the spherical particle for thermal spraying which has sufficient breaking strength and does not collapse even during the flame (plasma) during thermal spraying.
[Selection figure] None

Description

  The present invention relates to a method for producing spherical particles for thermal spraying comprising a rare earth element-containing oxide useful for thermal spraying of ceramics, metals and the like.

  Conventionally, plasma spraying, explosive spraying, and the like have been widely used as methods for forming a dense sprayed film on the surface of ceramics or metal. In these thermal spraying methods, metals, metal oxides, and the like are used as thermal spraying particles.

  As particles for thermal spraying to form such a thermal spray coating, (1) melt pulverization obtained by adjusting the particle size by melting the raw material in an electric furnace, cooling and solidifying, pulverizing with a pulverizer, and then classifying Powder, (2) After sintering the raw material, pulverized with a pulverizer, and then classified to obtain a sintered pulverized powder obtained by adjusting the particle size. (3) Add the raw material powder to an organic binder to make a slurry, and spray dry Examples thereof include granulated powder obtained by performing particle size adjustment by granulating using a mold granulator, drying, and optionally classifying. Here, the raw materials for powder production of the above (1) to (3) are appropriately selected and developed depending on the cost and the properties of the desired thermal spray coating.

By the way, in recent years, rare earth element-containing compounds are being developed as a wafer processing member in a halogen-based corrosive gas in a plasma process in semiconductor manufacturing because of its high plasma resistance.
When a thermal spray coating is used for a member of such a semiconductor manufacturing apparatus, characteristics required for the coating include (I) a small amount of impurity elements other than main constituent elements, and (II) a smooth surface of the coating with few particles. Thus, there are two, which means that there are few irregularities, that is, it means that dust generation during wafer processing is suppressed. In order to satisfy such requirements, it is important how to control the powder characteristics of the particles for thermal spraying in addition to the thermal spraying conditions.

  The characteristics of the particles for thermal spraying are (I) that the material does not collapse until the plasma flame or flame flame at the time of thermal spraying and can be supplied quantitatively, and (II) at the time of thermal spraying (in the plasma flame or flame flame) ) It is required that the particles are completely melted and (III) high purity, and these characteristics are quantitatively expressed by powder physical property values and elemental analysis values composed of more than ten items.

  By the way, since the above-mentioned spraying particles are supplied to the spraying gun through a narrow channel such as a transport tube, whether or not the spraying particles can be stably and quantitatively supplied depends on the flow properties of the spraying particles. It will be considerably influenced by sex.

  However, the melt pulverized powder and sintered pulverized powder obtained by the above methods (1) and (2) have a defect that the irregularity of the sprayed film increases because the shape is irregular. In addition, the melted and pulverized powder has a drawback that the content of impurities other than the constituent elements is high, and the sintered and pulverized powder has a disadvantage that impurities are easily mixed in the pulverizing step.

  As a solution to the problems of each of these pulverized powders, there is a granulated powder obtained by the method of (3) above, that is, a granulated powder having a characteristic of good fluidity because it is spherical or nearly spherical. It has been developed. In addition, this granulated powder has a feature that a relatively pure granulated powder can be easily produced by reducing impurities in the raw material used.

  However, depending on the raw material powder, when granulated, the particles collapse in the plasma, a granulated powder with a shape far from the spherical shape is obtained, or the raw material powder adheres around the granulated powder In particular, when the particle size is reduced, there is a problem that the fluidity is lowered.

Furthermore, fine particles that have not been granulated adhere to the film sprayed with the sprayed powder or on the film surface without melting, and there is a problem that dust generation increases when used in a semiconductor manufacturing apparatus or the like. .
On the other hand, when spraying particles for thermal spraying made of metal oxide or the like, in order to form a sprayed coating having no dust generation and excellent adhesion strength, the particles for thermal spraying are applied in a flame flame or plasma flame at the time of thermal spraying. It is necessary to melt completely and to precisely control the supply of thermal spray raw material.

  In particular, when a rare earth element-containing compound is used, since the melting point is high, it is preferable to use thermal spraying particles having a small average particle diameter in order to completely melt the compound.

  However, in the case of granulated powder using a spray granulator, it is difficult to produce only particles having a small average particle size, and there is a problem that particles having a relatively large average particle size are also generated. Such particles having a large average particle size are large in weight, and therefore do not melt completely even when supplied into the plasma flame, and are taken into the sprayed coating as unmelted particles, causing irregularities in the coating. It became one of.

  In order to solve the above problems, reducing the particle diameter of the raw material to suppress surface irregularities causes generation of particles, fluidity decreases, and precise quantitative supply cannot be performed, resulting in surface irregularities. There is a problem that the film can be formed and the film density decreases. Furthermore, there is a problem that particles that are not granulated and adhere to the surface do not enter the plasma flame during spraying and become unmelted and adhere to the sprayed coating or to the surface of the film.

In addition, the following are mentioned as prior literature relevant to the present invention.
JP-A-6-240435 JP-A-8-119632 JP-A-8-225917 JP-A-10-87325 JP-A-64-75657

  A first object of the present invention is to provide a method for producing spherical particles for thermal spraying that has sufficient fracture strength and does not collapse even during flame (plasma) during thermal spraying.

  Secondly, the present invention provides a method for producing high-purity spherical particles for thermal spraying that can form a smooth and dense thermal spray coating even when a high melting point rare earth element-containing compound is used. For the purpose.

  Furthermore, a third object of the present invention is to provide a method for producing spherical particles for thermal spraying that enables a smooth thermal spray member that does not adhere to fine powders when sprayed onto the surface of a substrate.

  The inventor of the present invention has arrived at the present invention as a result of intensive studies to achieve the above object.

That is, the first aspect of the present invention is a spherical particle for thermal spraying, which is formed from an oxide containing rare earth elements (including yttrium), has a fracture strength of 10 MPa or more, and an average particle size of 10 to 80 μm. A manufacturing method is provided.
The spherical particles for thermal spraying do not collapse even during the flame (plasma) during thermal spraying, and by using this, it is possible to form a thermal sprayed film without adhesion of unmelted particles on the surface and inside.

Further, the present invention is formed from an oxide containing rare earth elements (including yttrium), and has a cumulative pore volume with a bulk density of 1.0 g / cm ³ or more, an aspect ratio of 2 or less, and a pore radius of 1 μm or less. Provided is a method for producing spherical particles for thermal spraying, which is characterized by a spherical shape of less than 0.5 cm ³ / g. In this case, the 90 vol% particle size D90 in the particle size distribution is 100 μm or less, the ratio of the 50 vol% particle size D50 to the Fisher diameter in the particle size distribution is 5 or less, and further 10 vol% in the particle size distribution. It is preferable that the particle diameter D10 is 5 μm or more and the dispersion index is 0.6 or less.

  Therefore, in the present invention, the granulated powder obtained by granulating an oxide containing rare earth elements (including yttrium) having a Fischer diameter of 0.6 μm or less is fired at 1,200 to 1,800 ° C. A method for producing spherical particles for thermal spraying is provided. In this case, a solvent is added to a rare earth element (however, including yttrium) oxide containing a Fischer diameter of 0.6 μm or less and an average particle diameter of 0.01 to 5 μm to form a slurry, which is granulated and granulated powder. Is preferably obtained. The slurry preferably further contains an organic binder.

  In the thermal spraying particles formed from the rare earth element-containing oxide, the bulk density, cumulative pore volume and aspect ratio are controlled to predetermined values, and are made spherical, and the particle size distribution is sharpened as necessary. By controlling, there is no generation of particles, fluidity is good, dense and high strength, and it completely dissolves without disintegrating at the time of thermal spraying, and a coating formed by thermal spraying the thermal spraying particles is a conventional coating. Compared to the thermal spray coating, there is no adhesion of fine powder, smoothness and high purity, and excellent adhesion and corrosion resistance.

According to the spherical particle for thermal spraying of the present invention, the spherical particle for thermal spraying, which is formed of an oxide containing rare earth elements (including yttrium), has a fracture strength of 10 MPa or more and an average particle size of 10 to 80 μm. Since it is a particle, it is possible to provide spherical particles for thermal spraying that have sufficient breaking strength and that do not collapse even during flame spraying (plasma).
Further, according to the spherical particles for thermal spraying of the present invention, a spherical shape having a bulk density of 1.0 g / cm ³ or more, an aspect ratio of 2 or less, and a cumulative pore volume of 1 μm or less in pore diameter is less than 0.5 cm ³ / g. It is. Therefore, it is excellent in fluidity, and precise quantitative supply is possible without causing blockage of the thermal spray nozzle. As a result, the coating obtained by spraying the thermal spray particles can be made smooth and dense.

Hereinafter, the present invention will be described in more detail.
The first spherical particles for thermal spraying of the present invention are formed from a rare earth element (but including yttrium) -containing oxide, and have a fracture strength of 10 MPa or more and an average particle size of 10 to 80 μm.

  The fracture strength St in the present invention is a value obtained by the following equation using the compression load P (N) and particle size d (mm) measured with a micro compression tester (MCTM-500, manufactured by Shimadzu Corporation) as parameters. .

St = 2.8P / πd ²
Further, the average particle diameter is a value of D50 of the particle size distribution measured by a laser diffraction method, and the Fisher diameter is a value measured by a Fisher subsize sizer.

  As a rare earth element containing compound, an oxide is mentioned by the compound containing the rare earth element containing yttrium (Y), and an oxide is especially preferable from the point obtained by sintering.

As a more preferable rare earth element, one or more of 3A group rare earths including yttrium (Y) such as Y, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu can be used. As the rare earth element-containing oxide, it is particularly preferable to use yttrium oxide or ytterbium oxide.
Note that a complex oxide of the rare earth and one or more metals selected from Al, Si, Zr, In, and the like may be used.

In addition, in the present invention, when the breaking strength St of the spherical particles for thermal spraying is less than 10 MPa, the fracture strength is too low, so that there is a problem that the sprayed particles collapse and become fine powder in the flame (plasma) during thermal spraying. In this case, the upper limit of the fracture strength is not particularly limited, but is usually 300 MPa or less.
Further, when the average particle size is less than 10 μm, there is a problem that the yield decreases due to vaporization of the spray particles, and when it exceeds 80 μm, there is a problem that the spray particles are not melted and remain melted. A more preferable average particle diameter is 10 to 60 μm.

The manufacturing method of spherical particles for thermal spraying comprising a rare earth element-containing oxide according to the present invention comprises a granulated powder obtained by granulating a rare earth element-containing oxide having a Fischer diameter of 0.6 μm or less, particularly a rare earth oxide fine powder. A method of firing at 1,200 to 1,800 ° C. is preferred.
Here, if the Fischer diameter of the rare earth element-containing oxide exceeds 0.6 μm, it is difficult for the granulated powder to proceed in the firing step after granulation, and spherical particles for thermal spraying with high fracture strength cannot be obtained. In consideration of improving the breaking strength, the more preferable Fischer diameter is 0.4 μm or less.

  The production of spherical particles for thermal spraying according to the present invention can be specifically performed by the following procedure. First, a rare earth element-containing oxide fine powder having a Fisher diameter of 0.6 μm or less, particularly 0.1 to 0.6 μm, preferably an average particle diameter D50 of 0.01 to 5 μm, more preferably 0.1 to 1 μm. Then, a solvent such as water and alcohol such as isopropanol is added to prepare a slurry. The obtained slurry is granulated using a granulator such as a rolling granulator (rotating disk), spray granulator, compression granulator, fluid granulator, etc., and the average particle size is 10 to 80 μm. Particularly preferably, a granulated powder of 10 to 60 μm is obtained.

  At this time, in order to prevent the granulated powder from being broken during the recovery operation or the like, an organic substance that disappears in the firing process may be added to the raw material oxide before granulation. As such an organic substance, polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), polyvinyl pyrrolidone (PVP), methyl cellulose (MC), hydroxypropyl cellulose (HPC), polyethylene glycol, phenol resin, epoxy resin, or the like may be used. it can. The amount of the organic substance added is not particularly limited as long as no problem occurs in the firing step, but is preferably 0.1 to 5% by weight with respect to the rare earth element-containing oxide fine powder.

  Further, in the granulation process in the granulator, some non-spherical particles are generated, and such non-spherical particles also cause a decrease in the fluidity of the powder. It is preferable to separate the spherical particles and use only the spherical particles in the subsequent firing step.

  In this production method, the firing step is performed in the air or in an inert gas atmosphere or in a vacuum in an electric furnace or the like. At this time, the firing temperature when rare earth oxide is used as a raw material is 1,200 to 1. 800 ° C., more preferably 1,500 to 1,800 ° C. The firing time is preferably 5 minutes to 10 hours, particularly 1 to 5 hours.

  The thus-fired spherical particles for thermal spraying can be used for thermal spraying as they are, but usually there is often some fusion between the particles, and when exposed to high-temperature plasma in this state, As a result, the melting becomes insufficient, and as a result, it may be difficult to adhere to the substrate. For this reason, it is preferable to apply the particles after firing to a classifier such as a pulverizer, a pulverizer, a sieve or the like to form spherical particles for thermal spraying having an average particle size of 10 to 80 μm, each of which is an independent monodisperse particle. It is.

  The spherical particles for thermal spraying obtained by the above-described manufacturing method have a high breaking strength of 10 MPa or more, so that the particles do not break during powder transportation or thermal spraying. It is possible to obtain a film in a good state in which unmelted particles do not adhere to the surface and the inside.

The spherical particles for thermal spraying formed from the second rare earth element-containing oxide according to the present invention have a cumulative pore volume with a bulk density of 1.0 g / cm ³ or more, an aspect ratio of 2 or less, and a pore radius of 1 μm or less. It is characterized by a spherical shape of less than 0.5 cm ³ / g.

  As the rare earth element-containing compound in the present invention, an oxide containing a rare earth element (including yttrium) is mentioned in the same manner as described above, but an oxide is used because it is used by sintering in particular. In the case of an oxide, the fracture strength is preferably 10 MPa or more and 300 MPa or less as described above.

Here, as the rare earth-containing oxide, one or more of 3A group rare earth elements including yttrium (Y) can be used as described above, but Y, Eu, Gd, Tb, Dy, Ho, It is preferable to use one or more heavy rare earth-containing oxides selected from Er, Tm, Yb and Lu.
Note that a composite oxide of the rare earth-containing oxide and one or more metals selected from Al, Si, Zr, In, and the like may be used.

If the bulk density is less than 1.0 g / cm ³ , the particles tend to be weak because the particles are not dense, and there is a high possibility that the particles will collapse during thermal spraying. A more preferable bulk density is 1.2 to 5.0 g / cm ³ .
Further, when the cumulative pore volume is 0.5 cm ³ / g or more, the unevenness of the particle surface becomes large, and smooth particles cannot be obtained. That is, in order to obtain particles having relatively high fluidity even when the particle diameter is reduced, the cumulative pore volume having a pore radius of 1 μm or less needs to be less than 0.5 cm ³ / g.

Furthermore, in the region having a pore radius of 1 μm or less, the cumulative pore volume is preferably 0.3 cm ³ / g or less, and in this way, the fluidity of the particles can be further improved. The pore radius and cumulative pore volume can be measured with a mercury intrusion pore distribution measuring device.

The particles for thermal spraying of the rare earth element-containing oxide of the present invention have a spherical shape, and specifically, are particles having an aspect ratio of 2 or less. The aspect ratio is a ratio of the major axis to the minor axis of the particle, that is, the major axis / minor axis, and serves as an index indicating whether the shape is close to a sphere.
When the aspect ratio exceeds 2, the shape is far from a spherical shape such as an indefinite shape, a needle shape, a scale shape, and the fluidity is deteriorated. In this case, the lower limit of the aspect ratio is not particularly limited, but is preferably closer to 1.
In addition, the spherical shape in this invention shows the shape of the particle | grains whose aspect ratio is 2 or less, and is a concept also including a spherical shape or the shape close | similar to a spherical shape.

The spherical particles for thermal spraying of the second rare earth element-containing oxide of the present invention have the above physical property values, and the 90 vol% particle size D90 in the particle size distribution is 100 μm or less, and 50 vol in the particle size distribution. The ratio of the% particle size D50 to the Fischer diameter is preferably 5 or less.
Here, when the particle size D90 of 90 vol% exceeds 100 μm, it is not completely melted in the plasma flame, unmelted powder is formed, and the surface may be uneven.

In addition, when the ratio of the 50 vol% particle size D50 and the Fisher diameter in the particle size distribution is more than 5, coarse particles and fine powder increase, which may make accurate quantitative supply difficult. That is, if the above value is 5 or less, more preferably 1 to 3, it is judged that there are few coarse particles and fine powder. Even if the pores formed on the surface are small, the ratio between D50 and the Fischer diameter is small, so that quantitative supply is possible, and even if the particle diameter is small, precise quantitative supply is possible. As a result, it is possible to form a smooth and dense thermal spray coating by using the thermal spray particles.
The Fischer diameter is a value measured with a Fisher subsizer.

  Since the Fischer diameter is a value calculated from the differential pressure of the gas when the gas is passed through the powder, it is affected by the average particle diameter, the particle size distribution, the surface condition of the particles, and the like. For this reason, when the average particle size is large, the particle size distribution is sharp, and / or the surface is smooth, the Fisher diameter is calculated to be large.

  Therefore, when the ratio (D50 / Fischer diameter) with the average particle diameter D50 is calculated, it can be said that the smaller the ratio, the sharper the particle size distribution or the smoother the particle surface. In particular, if the particle size distribution is the same, it is determined that there is a feature that the surface of the particle is smooth.

More preferably, the 10 vol% particle size D10 in the particle size distribution is 5 μm or more and the dispersion index is 0.6 or less.
That is, by setting D10 to 5 μm or more and the dispersion index to 0.6 or less, the generation of particles can be suppressed and the particle size distribution can be sharpened. Further, the fluidity of the particles is improved, and blockage in the nozzle can be prevented when the powder is supplied.

The dispersion index can be obtained by the following formula.
Dispersion index = (D90−D10) / (D90 + D10)

  Further, in consideration of further improving the fluidity of the particles, it is preferable to control the dispersion index to 0.1 to 0.5 and to control the repose angle of the particles to 44 ° or less.

Moreover, it is preferable that the specific surface area of the spherical particle for thermal spraying of a rare earth element containing oxide is 2.0 m < ² > / g or less, More preferably, it is 0.1-1.5 m < ² > / g.
Here, when the specific surface area exceeds 2.0 m ² / g, the constituent particles are liable to collapse, which may cause dust generation.

  Further, the spherical particles for thermal spraying of the rare earth element-containing oxide have a high purity of the coating formed by spraying the spherical particles for thermal spraying, prevent the occurrence of colored spots, and have sufficient corrosion resistance for the thermal spraying member having the coating. In consideration of the provision of iron, iron group elements (Fe, Ni, Co, etc.), alkali metal elements (Na, K, etc.), and alkaline earth metal elements (Mg, Ca, etc.) are each 5 ppm or less in terms of oxides. It is preferable that The smaller the amount of each metal element, the better. However, the lower limit is usually about 0.1 ppm.

  The iron group element, alkali metal element, and alkaline earth metal element were measured by ICP spectroscopic analysis (inductively coupled high-frequency plasma spectroscopic analysis) after acid-decomposing the spherical particles for thermal spraying of the rare earth element-containing oxide. Is.

  Furthermore, it is preferable that carbon is 100 ppm or less. By suppressing the carbon to 100 ppm or less, it is possible to prevent the bonding of particles in the thermal spray film from being weakened by the residual carbon, and as a result, it is possible to reduce dust generation. Therefore, even when granulating using a binder, it is preferable to perform sintering with as little carbon residue as possible so as not to generate raw material carbides.

  By the way, in a polycrystalline particle, it is thought that it is so dense that the particle size of the single crystal particle which comprises particle | grains is large. The particle diameter of the single crystal particles constituting such particles is called a crystallite. In the spherical particles for thermal spraying of the rare earth element-containing oxide, the crystallite is preferably 25 nm or more, more preferably 50 nm or more. is there. When the crystallite is less than 25 nm, it is considered that the crystallite is often not dense because it is a polycrystalline particle having a small particle size.

  The crystallite is a value obtained from the Wilson method of X-ray diffraction. In the Wilson method, the crystallites are in the range of 0 to 100 nm, no matter how large the single crystal particle size is.

  In the above, spherical particles for thermal spraying of a rare earth element-containing oxide can be obtained as follows, as described above.

The primary particle has a Fischer diameter of 0.6 μm or less, particularly 0.1 to 0.6 μm, preferably an average particle diameter of 0.01 to 5 μm, more preferably 0.01 to 1 μm. A slurry is prepared by adding it together with a binder to alcohol, etc., granulated with a rolling granulator, spray granulator, compression granulator, fluid granulator, etc. It is fired in an active gas or under vacuum at 1,200 to 1,800 ° C., preferably 1,500 to 1,800 ° C. for 5 minutes to 10 hours, preferably 1 to 5 hours, and the particle size D90 in the particle size distribution is 100 μm. And a fluidity having a spherical shape with a ratio of D50 to Fischer diameter of 5 or less, a bulk density of 1.0 g / cm ³ or more, a cumulative pore volume of less than 0.5 cm ³ / g, and an aspect ratio of 2 or less. Of rare earth element-containing oxides Obtaining spherical particles for morphism.

  Examples of the binder include celluloses such as polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), hydroxypropyl cellulose (HPC), methyl cellulose (MC), polyvinyl pyrrolidone (PVP), polyethylene glycol (PEG), polytetrafluoroethylene ( PTFE), a phenol resin, an epoxy resin, and the like can be used, and these are added in an amount of 0.1 to 5% by weight with respect to the rare earth element-containing oxide.

  As described above, the particles for thermal spraying of the rare earth element-containing oxide according to the present invention are spherical, are composed of fine particles, have few particles, and are smooth with few irregularities on the particle surface. Therefore, since it is excellent in fluidity, precise quantitative supply is possible without causing the thermal spray nozzle to be clogged. As a result, the coating obtained by spraying the thermal spray particles can be made smooth and dense with few adhered particles.

A thermal spray member according to the present invention includes a base material, and a coating formed by spraying the above-described spherical particles for thermal spraying of the first and second rare earth element-containing oxides on the surface of the base material. .
Here, the substrate is not particularly limited, and metals, alloys, ceramics, glass, and the like can be used. Specifically, Al, Fe, Ni, Cr, Zn, Zr, Si, and alloys thereof, Examples thereof include oxides, nitrides, carbides, and the like, such as alumina, aluminum nitride, silicon nitride, silicon carbide, quartz glass, zirconia, and the like.

  The thickness of the coating on the substrate surface is preferably 50 to 500 μm, more preferably 150 to 300 μm. When the thickness of the coating is less than 50 μm, when a thermal spray member having the coating is used as a corrosion-resistant member, it may be necessary to replace it with a slight corrosion. On the other hand, when the thickness of the coating exceeds 500 μm, there is a possibility that peeling inside the coating tends to occur because it is too thick.

  Moreover, it is preferable that the surface roughness of a film is 60 micrometers or less, More preferably, it is 40 micrometers or less. If the surface roughness exceeds 60 μm, it may cause dust generation during use of the thermal spray member, and since the plasma contact area increases, corrosion resistance may be deteriorated, and particles are generated due to the progress of corrosion. There is a fear.

That is, when the surface roughness of the coating is 60 μm or less, good corrosion resistance is obtained and particles attached to the film surface are reduced. Therefore, corrosion hardly occurs even in an atmosphere of corrosive gas (such as a halogen-based gas plasma), and the sprayed member can be suitably used as a corrosion-resistant member, and the particles for spraying the rare earth element-containing oxide are used. Thus, a member with less dust generation of 10 or less 100 μm ^{2 of} unfused deposit particles on the coating surface is obtained.

The thermal spray member of the present invention can be obtained by forming a coating film on the surface of the substrate by plasma spraying or low pressure plasma spraying of the above-mentioned rare earth element-containing oxide spray particles. Here, the plasma gas is not particularly limited, and nitrogen / hydrogen, argon / hydrogen, argon / helium, argon / nitrogen, or the like can be used.
The spraying conditions and the like are not particularly limited, and may be set as appropriate according to the specific material such as the base material, particles for spraying the rare earth element-containing oxide, the use of the obtained sprayed member, and the like.

  Also in the thermal spray member of the present invention, it is preferable that the iron group element, alkali metal element, and alkaline earth metal element in the coating are each 5 ppm or less in terms of oxides. Can be achieved by forming a coating film using particles for spraying rare earth element-containing oxides of 5 ppm or less.

  That is, when a coating is formed using spherical particles for thermal spraying in which iron group elements, alkali metal elements, and alkaline earth metal elements are mixed in an oxide equivalent of 5 ppm or more, the coating is mixed with the spherical particles for thermal spraying. Since only iron group elements, alkali metal elements, and alkaline earth metal elements are mixed as they are, there is a concern of wafer defects when used for semiconductor manufacturing equipment.

  As explained above, the thermal spray member according to the present invention has a surface purity of 60 μm or less, and high purity of iron group elements, alkali metal elements, and alkaline earth metal elements of 5 ppm or less in terms of oxides. And a smooth and dense film.

  Therefore, since particles generated at the time of plasma etching are few and impurities can be prevented from being mixed into the processing wafer, the sprayed member can be used without problems in an apparatus that is required to have high purity. Specifically, it can be suitably used as a member for a liquid crystal manufacturing apparatus and a member for a semiconductor manufacturing apparatus.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited to the following Example.

[Example 1]
10 g of methylcellulose was added to 5 kg of yttrium oxide having a Fischer diameter of 0.45 μm, and pure water was added to make a water slurry of about 40% by weight. This water slurry was granulated with a spray dryer to obtain a granulated powder having an average particle size of about 50 μm.
The granulated powder was fired at 1,600 ° C. for 2 hours in an electric furnace in an air atmosphere and then cooled. The obtained powder was passed through a sieve having an opening of 150 μm to obtain a spherical sprayed powder having an average particle diameter of 50 μm. The fracture strength of the obtained spherical particles for thermal spraying was measured and found to be about 13 MPa.
The fracture strength was measured using a flat indenter at a test load of 980 mN and a load speed of about 41.5 mN / sec.

[Example 2]
Spherical particles for thermal spraying having an average particle diameter of 50 μm were produced in the same manner as in Example 1 except that the Fischer diameter of yttrium oxide was 0.28 μm. When the fracture strength of the obtained spherical particles for thermal spraying was measured, it was about 160 MPa.

[Example 3]
Spherical particles for thermal spraying having an average particle size of 49 μm were produced in the same manner as in Example 1 except that the Fischer diameter of yttrium oxide was 0.35 μm. The fracture strength of the obtained spherical particles for thermal spraying was measured and found to be about 130 MPa.

[Example 4]
Spherical particles for thermal spraying having an average particle diameter of 50 μm were produced in the same manner as in Example 1 except that ytterbium oxide having a Fisher diameter of 0.28 μm was used. When the fracture strength of the obtained spherical particles for thermal spraying was measured, it was about 160 MPa.

[Example 5]
Spherical particles for thermal spraying having an average particle diameter of 50 μm were produced in the same manner as in Example 1 except that ytterbium oxide having a Fisher diameter of 0.30 μm was used. The fracture strength of the obtained spherical particles for thermal spraying was measured and found to be about 120 MPa.

[Comparative Example 1]
Spherical particles for thermal spraying having an average particle diameter of 50 μm were produced in the same manner as in Example 1 except that the Fischer diameter of yttrium oxide was 1.5 μm. The fracture strength of the obtained spherical particles for thermal spraying was measured and found to be about 2 MPa.

  Table 1 below summarizes the raw material powder, the raw material Fischer diameter, the firing temperature, the average particle diameter of the spraying spherical particles, and the fracture strength in each of the above Examples and Comparative Examples.

As shown in the results of the above Examples and Comparative Examples, the spherical particles for thermal spraying obtained using a raw material oxide having a Fischer diameter of 0.6 μm or less have a fracture strength exceeding 10 MPa and exceeding 50 MPa ( It can be seen that Examples 2 to 5) are also obtained.
In addition, when the spherical particles for thermal spraying obtained in each example and comparative example were sprayed onto a substrate made of alumina ceramics using a plasma spraying machine, the spherical strength for thermal spraying obtained in each example exceeded 10 MPa. In the case of particles, fine particles due to particle destruction were not generated during spraying, and a good sprayed film was obtained.

  Thus, the spherical particles for thermal spraying according to the present invention are configured to contain rare earth oxide (including yttrium), have a fracture strength of 10 MPa or more, and an average particle size of 10 to 80 μm. Therefore, flame spraying and plasma spraying are performed. When a thermal spray coating is formed by using, for example, a flame (plasma), it does not break down into fine particles, and by using this for thermal spraying, a good thermal spray film with no fine particles attached can be obtained.

[Example 6]
A slurry is prepared by dispersing 8 kg of yttrium oxide having a Fisher diameter of 0.5 μm and Fe ₂ O ₃ of 0.5 ppm or less in 12 liters of pure water in which 15 g of PVA (polyvinyl alcohol) is dissolved. The slurry was spray-dried to produce spherical granulated powder.
Furthermore, the obtained granulated powder was fired at 1,600 ° C. for 2 hours in the air to obtain spherical particles for thermal spraying.

The particle diameter of the spherical particles for thermal spraying obtained by the above production process was measured with a laser diffraction type particle size measuring instrument. As a result, D90 was 45 μm. The bulk density was 1.86 g / cm ³ , the specific surface area measured by the BET method was 0.6 m ² / g, and the cumulative pore volume with a pore radius of 1 μm or less was 0.18 cm ³ / g. The ratio between the average particle diameter D50 and the Fisher diameter was 2.25, and the aspect ratio was 1.01.

The resulting spray spherical particles by decomposing acid was measured impurity concentration by ICP spectrometry (inductively coupled plasma spectrometry), Fe ₂ O ₃ is 1 ppm, CaO is 2 ppm, Na ₂ O by atomic absorption Was 5 ppm, and the carbon concentration was 70 ppm. The cumulative pore volume was measured with a mercury intrusion autoscan type 33 manufactured by Yuasa Ionics.

Further, the spray particles were plasma sprayed with argon / hydrogen to form a 190 μm-thick film on an aluminum alloy substrate (No. 6061 described in JIS H4000). There was no nozzle clogging during spraying. When the surface roughness, which is an index representing the smoothness of the obtained film, was measured, Rmax (based on JIS B0601) was 48 μm.
Moreover, the relative density of the coating was measured for the purpose of examining the density of the obtained sprayed coating. The relative density was measured by Archimedes method after the sprayed coating was immersed in dilute hydrochloric acid and peeled off from the substrate. As a result, the relative density was 92%.

[Example 7]
A slurry was prepared by dispersing 4 kg of ytterbium oxide having a Fischer diameter of 0.4 μm and Fe ₂ O ₃ of 0.5 ppm or less in 16 liters of pure water in which 15 g of CMC (carboxymethylcellulose) was dissolved. The slurry was spray-dried to produce spherical granulated powder. Furthermore, this granulated powder was fired at 1,500 ° C. for 2 hours in the air to obtain spherical particles for thermal spraying.
The particles for thermal spraying obtained by the above production process were measured with a laser diffraction particle size measuring device. D90 was 36 μm, bulk density was 2.2 g / cm ³ , and specific surface area by BET method was 0.5 m ² / g. The cumulative pore volume with a pore radius of 1 μm or less was 0.04 cm ³ / g, the ratio of the average particle diameter D50 to the Fisher diameter was 2.05, and the aspect ratio was 1.02.

The obtained thermal spray particles were acid-decomposed, and the impurity concentration was measured by ICP spectroscopic analysis (inductively coupled high-frequency plasma spectroscopic analysis). Fe ₂ O ₃ was 1 ppm, CaO was 3 ppm, and Na ₂ O by atomic absorption was The concentration was 4 ppm and the carbon concentration was 60 ppm.
Further, the spray particles were plasma sprayed with argon / hydrogen to form a 210 μm-thick film on the aluminum alloy substrate. There was no nozzle clogging during spraying. When the surface roughness of this sprayed coating was measured, it was 39 μm in Rmax.
Further, the relative density of the film was measured in the same manner as in Example 6 for the purpose of examining the density of the obtained sprayed film. As a result, the relative density was 90%.

[Example 8]
A slurry is prepared by dispersing 2 kg of yttrium oxide having a Fischer diameter of 0.3 μm and Fe ₂ O ₃ of 0.5 ppm or less in 18 liters of pure water in which 30 g of PEO (polyethylene oxide) is dissolved. Was spray-dried to produce spherical granulated powder. Furthermore, this granulated powder was fired at 1,650 ° C. for 2 hours in the atmosphere to obtain spherical particles for thermal spraying.

When the spherical particles for thermal spraying obtained by the above production process were measured with a laser diffraction particle size measuring device, the D90 was 28 μm, the bulk density was 1.6 g / cm ³ , and the specific surface area by the BET method was 0.7 m ² / g, the cumulative pore volume with a pore radius of 1 μm or less was 0.04 cm ³ / g, the ratio of the average particle diameter D50 to the Fisher diameter was 2.13, and the aspect ratio was 1.01.

The obtained thermal spray particles were acid-decomposed and the impurity concentration was measured by ICP spectroscopic analysis (inductively coupled high-frequency plasma spectroscopic analysis). As a result, Fe ₂ O ₃ was 3 ppm, CaO was 3 ppm, and Na ₂ O by atomic absorption was The concentration was 4 ppm and the carbon concentration was 60 ppm.
Further, the spray particles were sprayed under reduced pressure with argon / hydrogen to form a 200 μm-thick film on the silicon substrate. There was no nozzle clogging during spraying. The surface roughness of the sprayed coating was measured and found to be 26 μm in Rmax.
Further, the relative density of the film was measured in the same manner as in Example 6 for the purpose of examining the density of the obtained sprayed film. As a result, the relative density was 91%.

[Example 9]
A slurry was prepared by dispersing 8 kg of yttrium oxide having a Fischer diameter of 0.6 μm and Fe ₂ O ₃ of 0.5 ppm or less in 12 liters of pure water in which 15 g of PVA (polyvinyl alcohol) was dissolved. The slurry was spray-dried to produce spherical granulated powder. Furthermore, this granulated powder was baked at 1,600 ° C. for 2 hours in the atmosphere, and then the fine powder was removed with a classifier to obtain spherical particles for thermal spraying.

The spherical particles for thermal spraying obtained by the above production process were measured with a laser diffraction particle size measuring device. D90 was 39 μm, D10 was 23 μm, the dispersion index was 0.25, the aspect ratio was 1.02, and the bulk density was 1.5 g / cm ^3, the cumulative follows pore radius 1μm pore volume 0.19 cm ³ / g, and the angle of repose was 38 °.
The resulting spray spherical particles by decomposing acid was measured impurity concentration by ICP spectrometry (inductively coupled plasma spectrometry), Fe ₂ O ₃ is 1 ppm, CaO is 2 ppm, Na ₂ O by atomic absorption Was 5 ppm, and the carbon concentration was 70 ppm.

Further, the spherical particles for thermal spraying were plasma sprayed with argon / hydrogen to form a 190 μm-thick film on the aluminum alloy substrate. There was no nozzle clogging during spraying.
The surface of the obtained sprayed member was observed with an electron microscope, and 5 μm or less unfused adhered particles present in an area of 100 μm square were counted.

[Example 10]
A slurry is prepared by dispersing 4 kg of ytterbium oxide having a Fischer diameter of 0.4 μm and Fe ₂ O ₃ of 0.5 ppm or less in 16 liters of pure water in which 15 g of PEO (polyethylene oxide) is dissolved. Was spray-dried to produce spherical granulated powder. Furthermore, this granulated powder was baked at 1,500 ° C. in the atmosphere for 2 hours, and then the fine powder was removed with a classifier to obtain spherical particles for thermal spraying.

The spherical particles for thermal spraying obtained by the above production process were measured with a laser diffraction particle size measuring device. D90 was 37 μm, D10 was 16 μm, the dispersion index was 0.40, the aspect ratio was 1.01, and the bulk density was The accumulated pore volume was 1.8 g / cm ³ , the pore radius was 1 μm or less, 0.04 cm ³ / g, and the angle of repose was 40 °.

The obtained spherical particles for thermal spraying were acid-decomposed and measured for impurity concentration by ICP spectroscopic analysis (inductively coupled high-frequency plasma spectroscopic analysis). Fe ₂ O ₃ was 1 ppm, CaO was 3 ppm, and Na ₂ O by atomic absorption was measured. Was 4 ppm, and the carbon concentration was 70 ppm.
Further, the spherical particles for thermal spraying were plasma sprayed with argon / hydrogen to form a film having a thickness of 210 μm on the aluminum alloy substrate. There was no nozzle clogging during spraying.
The surface of the obtained sprayed member was observed with an electron microscope, and 5 μm or less unfused adhered particles present in an area of 100 μm square were counted.

[Example 11]
A slurry is prepared by dispersing 2 kg of yttrium oxide having a Fisher diameter of 0.3 μm and Fe ₂ O ₃ of 0.5 ppm or less in 18 liters of pure water in which 15 g of MC (methyl cellulose) is dissolved. Was spray-dried to produce spherical granulated powder. Furthermore, this granulated powder was baked at 1,500 ° C. in the atmosphere for 2 hours, and then the fine powder was removed with a classifier to obtain spherical particles for thermal spraying.

The spherical particles for thermal spraying obtained by the above production process were measured with a laser diffraction particle size measuring device. As a result, D90 was 34 μm, D10 was 16 μm, the dispersion index was 0.36, the aspect ratio was 1.01, and the bulk density was The accumulated pore volume was 2.2 g / cm ³ , the pore radius was 1 μm or less, 0.03 cm ³ / g, and the angle of repose was 42 °.

The resulting spray spherical particles by decomposing acid was measured impurity concentration by ICP spectrometry (inductively coupled plasma spectrometry), Fe ₂ O ₃ is 3 ppm, CaO is 3 ppm, Na ₂ O by atomic absorption Was 4 ppm, and the carbon concentration was 50 ppm.
Further, the spherical particles for thermal spraying were plasma sprayed with argon / hydrogen to form a coating having a thickness of 200 μm on the quartz substrate. There was no nozzle clogging during spraying.
The surface of the obtained sprayed member was observed with an electron microscope, and the number of unmelted adhering particles of 5 μm or less existing in an area of 100 μm square was 2.

[Example 12]
A slurry is prepared by dispersing 2 kg of yttrium aluminum garnet having a Fischer diameter of 4 μm in 18 liters of pure water in which 15 g of PVA (polyvinyl alcohol) is dissolved. After baking at 500 ° C. for 2 hours, fine powder was removed with a classifier to obtain spherical particles for thermal spraying.

The spherical particles for thermal spraying obtained by the above production process were measured with a laser diffraction type particle size measuring device. D90 was 36 μm, D10 was 15 μm, dispersion index was 0.41, aspect ratio was 1.06, and bulk density was The accumulated pore volume was 1.1 g / cm ³ and the pore radius was 1 μm or less, and the volume was 0.3 cm ³ / g.

The resulting spray spherical particles by decomposing acid was measured impurity concentration by ICP spectrometry (inductively coupled plasma spectrometry), Fe ₂ O ₃ is 4 ppm, CaO is 4 ppm, Na ₂ O by atomic absorption Was 5 ppm, and the carbon concentration was 65 ppm.
Further, the spherical particles for thermal spraying were plasma sprayed with argon / hydrogen to form a film having a film thickness of 203 μm on the aluminum alloy substrate. There was no nozzle clogging during spraying.
The surface of the obtained sprayed member was observed with an electron microscope, and the number of unmelted adhering particles of 5 μm or less existing in an area of 100 μm square was 2.

[Example 13]
A slurry is prepared by dispersing 2 kg of ytterbium silicate with a Fischer diameter of 0.6 μm in 18 liters of pure water in which 15 g of PVA (polyvinyl alcohol) is dissolved. , And calcined at 500 ° C. for 2 hours, after which fine powder was removed with a classifier to obtain spherical particles for thermal spraying.

The spherical particles for thermal spraying obtained by the above production process were measured with a laser diffraction particle size measuring device. D90 was 33 μm, D10 was 14 μm, the dispersion index was 0.40, the aspect ratio was 1.1, and the bulk density was The cumulative pore volume was 1.9 g / cm ³ and the pore radius was 1 μm or less, which was 0.28 cm ³ / g.

The resulting spray spherical particles by decomposing acid was measured impurity concentration by ICP spectrometry (inductively coupled plasma spectrometry), Fe ₂ O ₃ is 3 ppm, CaO is 5 ppm, Na ₂ O by atomic absorption Was 4 ppm, and the carbon concentration was 72 ppm.
Further, the spherical particles for thermal spraying were plasma sprayed with argon / hydrogen to form a film having a thickness of 194 μm on the aluminum alloy substrate. There was no nozzle clogging during spraying.
The surface of the obtained sprayed member was observed with an electron microscope, and 5 μm or less unfused adhered particles present in an area of 100 μm square were counted.

[Comparative Example 2]
A slurry was prepared by dispersing 8 kg of yttrium oxide having a Fisher diameter of 1.1 μm and Fe ₂ O ₃ of 0.5 ppm or less in 12 liters of pure water in which 15 g of PVA (polyvinyl alcohol) was dissolved. The slurry was spray-dried to produce spherical granulated powder. Furthermore, this granulated powder was baked at 1,600 ° C. for 2 hours in the air to obtain spherical particles for thermal spraying.

The spherical particles for thermal spraying obtained by the above production process were measured with a laser diffraction type particle size measuring device. The D90 was 106 μm, the bulk density was 1.1 g / cm ³ , and the specific surface area by BET method was 1.4 m ² / g. The cumulative pore volume with a pore radius of 1 μm or less was 0.55 cm ³ / g, the ratio of the average particle diameter D50 to the Fisher diameter was 6.93, and the aspect ratio was 1.1.

The obtained spherical particles for thermal spraying were acid-decomposed and measured for impurity concentration by ICP spectroscopic analysis (inductively coupled high-frequency plasma spectroscopic analysis). Fe ₂ O ₃ was 3 ppm, CaO was 2 ppm, and Na ₂ O by atomic absorption was measured. Was 5 ppm, and the carbon concentration was 80 ppm.
Further, the spherical particles for thermal spraying were plasma sprayed with argon / hydrogen to form a coating film having a film thickness of 195 μm on the aluminum alloy substrate. There was no nozzle clogging during spraying. When the surface roughness of this sprayed coating was measured, it was 88 μm in Rmax.
Further, the relative density of the film was measured in the same manner as in Example 6 for the purpose of examining the density of the obtained sprayed film. As a result, the relative density was 84%.

[Comparative Example 3]
3 kg of yttrium oxide having a Fischer diameter of 4 μm was melted and solidified, and then pulverized and classified to produce particles for thermal spraying.
The particles for thermal spraying obtained by the above production process were measured with a laser diffraction particle size measuring instrument. As a result, D90 was 110 μm, bulk density was 2.1 g / cm ³ , specific surface area by BET method was 0.1 m ² / g, The cumulative pore volume with a pore radius of 1 μm or less was 0.01 cm ³ / g or less, the ratio of the average particle diameter D50 to the Fisher diameter was 3.05, and the aspect ratio was 2.6.

The obtained thermal spray particles were acid-decomposed and the impurity concentration was measured by ICP spectroscopic analysis (inductively coupled high-frequency plasma spectroscopic analysis). As a result, Fe ₂ O ₃ was 55 ppm, CaO was 40 ppm, and Na ₂ O by atomic absorption was The concentration was 10 ppm and the carbon concentration was 92 ppm.

Further, the thermal spraying particles were subjected to low-pressure plasma spraying with argon / hydrogen to form a 190 μm-thick film on the aluminum alloy substrate. There was no nozzle clogging during spraying. When the surface roughness of this sprayed coating was measured, it was 94 μm in Rmax.
Further, the relative density of the film was measured in the same manner as in Example 6 for the purpose of examining the density of the obtained sprayed film. As a result, the relative density was 91%.

The spherical particles for thermal spraying of rare earth element-containing oxides obtained in Examples 6 to 8 above all have a D90 in the particle size distribution of 100 μm or less and a ratio of D50 to the Fisher diameter of 5 or less and a bulk density. 1.0 g / cm ³ or more, a pore radius of 1 μm or less, a cumulative pore volume of less than 0.5 cm ³ / g, an aspect ratio of 2 or less, and a spherical shape, and Fe ₂ O ₃ , CaO, Na ₂ O Are each less than 5 ppm and have few impurities.

Therefore, a high-purity sprayed coating can be formed, and the obtained coating surface is smooth and dense, so that the sprayed coating is difficult to peel off. As a result, particles generated during the semiconductor manufacturing process can be suppressed, and it can be suitably used as an application that requires high purity, for example, a member for a liquid crystal manufacturing apparatus and a member for a semiconductor manufacturing apparatus.
Furthermore, the surface roughness is as small as 60 μm or less, and it can be suitably used as a corrosion-resistant member against a corrosive gas atmosphere (for example, halogen-based gas plasma).

Moreover, the particles for thermal spraying of the rare earth element-containing oxides obtained in Examples 9 to 13 are particles that enable precise quantitative supply even with a small particle diameter, and in a region where the pore radius is 1 μm or less. Cumulative pore volume is less than 0.5 cm ³ / g, aspect ratio is 2 or less, bulk density is 1.0 g / cm ³ or more, D10 in particle size distribution is 5 μm or more, D90 is 100 μm or less, and dispersion index is 0 and at .6 or less, _{moreover, Fe 2 O 3, CaO,} Na 2 O is of 5ppm or less and less impurities high purity, respectively.

Therefore, the coating using the spherical particles for thermal spraying can be highly purified, and the number of unfused adhered particles of 5 μm or less on the surface of the coating is 10 or less in 100 μm square. Particles generated therein can be suppressed, and it can be suitably used as an application requiring high purity, for example, a member for liquid crystal manufacturing apparatus and a member for semiconductor manufacturing apparatus.
Further, the surface roughness is small, and it can be suitably used as a corrosion-resistant member against a corrosive gas atmosphere (for example, halogen-based gas plasma).

  In contrast, the spherical particles for thermal spraying of Comparative Example 2 have a large D90 of 106 μm, and the ratio of the average particle diameter D50 to the Fisher diameter is 6.93, so that the surface roughness of the obtained thermal spray coating is Therefore, the generation of particles during the semiconductor manufacturing process cannot be suppressed.

The particles for thermal spraying of Comparative Example 3 have a small ratio of the average particle diameter D50 to the Fischer diameter of 3.05, and the resulting coating has a large relative density, but the iron group elements are only mixed in the thermal spraying particles. , Alkaline metal elements and alkaline earth metal elements are present, and when used in semiconductor manufacturing processes, etc., silicon wafers are contaminated and cause process defects. It cannot be used for purposes.
Further, the surface roughness is as high as 94 μm, which causes generation of particles during the semiconductor manufacturing process, and this particle is also undesirable because it causes silicon wafer contamination.

Claims (3)

  For thermal spraying, characterized in that a granulated powder obtained by granulating an oxide containing a rare earth element (but including yttrium) having a Fischer diameter of 0.6 μm or less is fired at 1,200 to 1,800 ° C. A method for producing spherical particles.   A slurry is added to a rare earth element (but containing yttrium) oxide containing a Fischer diameter of 0.6 μm or less and an average particle diameter of 0.01 to 5 μm to form a slurry, which is granulated to obtain a granulated powder. The manufacturing method according to claim 1. The production method according to claim 2, wherein the slurry further contains an organic binder.