CZ20013545A3 - Metallic seamless tube and process for producing thereof - Google Patents

Abstract

A metal-made seamless pipe contains, as a main component, at least one kind of metal selected from the group consisting of metals each having a melting point of 1,600 DEG C or more. The metal-made seamless pipe has a porosity of 0.3 to 25% when the porosity is defined as a proportion of the open pores not perforating in the thickness direction of the pipe, present at the outer surface of the pipe, to the total area (100%) of the outer surface of the pipe; and a process for producing such a metal-made seamless pipe. The metal-made seamless pipe is low in processability but can be produced in a small thickness and a small inner diameter, is superior in mechanical strengths and gastightness, and can be suitably used as a sealing member of a translucent vessel of a high-pressure discharge lamp.

Description

The present invention relates to a metal seamless pipe and to a method for producing a similar pipe. In particular, the present invention relates to a metal seamless pipe which is labor intensive but can be manufactured with a small thickness and a small inner diameter which has improved mechanical strength and airtightness and which is preferably used, for example, as a sealing member of a translucent housing (e.g., a ceramic translucent housing) that is part of, for example, a high pressure discharge lamp (e.g., metal halide lamps). The present invention also relates to a method of manufacturing such a metal seamless tube.

BACKGROUND OF THE INVENTION

As shown in Fig. 5, the translucent ceramic tube 20 (translucent tube) is used as a translucent housing of a high pressure discharge lamp 10 (e.g., metal halide lamps) since the translucent housing contains a light emitting material (e.g. dysprosium iodide) which is highly corrosive. therefore, the translucent housing must be corrosion resistant.

For sealing the translucent ceramic tube 20 (translucent tube), which is used as a translucent sleeve, a metal tube 30 (e.g., molybdenum tube) has been proposed as a sealing member - see European patent specification EP

0982278A1.

However, it must be said that metals (such as tungsten that are used in pipes) are very difficult to process, limiting the production of pipes with • · • ·

9 * 9 molybdenum or the manufacture of said metal resulting in small thicknesses and small internal diameters.

As well as the complexity of machining and cutting of metals, the manufacture of metal tubes of metals consists in the sintering of metal ingots, the subsequent rolling of the metal ingot, its drawing or the like to deliver pipe material.

When using such manufacturing processes, it is extremely difficult to obtain metal pipes with small thicknesses and small diameters.

SUMMARY OF THE INVENTION

In view of the above problems, it is an object of the present invention to provide a metal seamless pipe that is difficult to process but can be manufactured with a small thickness and a small inside diameter that has improved mechanical strength and airtightness and is preferably, for example, as a sealing member of a translucent housing (e.g., a ceramic translucent housing), which would be part of, for example, a high-pressure discharge lamp (e.g., metal halide lamps). The present invention

It is furthermore an object of the present invention to provide a method for producing such a metal seamless tube.

In order to solve the above object, the present invention proposes the following metal seamless pipe and a method for its manufacture:

[1]

A metal seamless tube containing at least one type of metal selected from the group consisting of metals, each having a melting point of 1600 ° C or more, the tube having a porosity of 0.3 to 25%, the porosity of which is defined as the ratio of the open pore area, which does not perforate the thickness of the tube and are located on the outer surface of the tube, to the total area (100%) of the outer surface of the tube.

[2]

Metal seamless pipe that Yippee in compliance with point [ib wherein the metals are at a temperature melting 1600 Noc: 2 ° C or more, are Mo, W, Re, Ti, Hf and Zr. [3] Metal seamless pipe that Yippee in compliance with point [1] wherein the melting temperature of each metal Yippee 2600 ° C or more [4] Metal seamless pipe that Yippee in compliance with point [3],

wherein the metals having a melting point of 2600 ° C or more are Mo, W and Re.

-4 · 0 0 0 0 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 [5]

A metal seamless tube which is in accordance with any one of [1] to [4], having an inner diameter of 0.4 to 3.0 mm and a thickness of 0.05 to 1.0 mm.

[6]

The metal seamless pipe, which is in accordance with any of the points —a-to- [5], further comprising cd — except — products — at least — one of the dodecoxide selected from the group consisting of Α1 ₂ 0 ₃ , Y2O3, Dy2O ₃ , Gd ₂ O ₃ , H ₂ O ₃ and Tm ₂ O 3, in an amount of 0.02 to 5% by volume relative to 100% of the total metal and oxide volume.

[7]

A method of manufacturing a metal seamless tube comprising:

- preparing a mixture comprising (1) 80 to 98 wt. a powder of at least one type of metal selected from the group consisting of metals each having a melting point of 1600 ° C or more, and (2) an adhesive in a solvent,

mixing the mixture for 0 to 3 hours and then extruding the mixed material into a tube, and

- drying the tube-shaped material at a temperature of -5 to 25 ° C for (at least) 10 hours to (maximum) 48 hours after completion of the extrusion, followed by drying at 30 to 120 ° C for 0.5 to 8 hours and thereafter firing dried material at a lower temperature, selected from a temperature range

1000 to 2100 ^e C, and at a temperature 300 ° C lower than the melting point of the metal.

[8]

A method for producing a metal seamless tube according to [7], wherein the metals having a melting point of 1600 ° C or more are Mo, W, Re, Ti, Hf and Zr.

[9]

A method of producing a metal seamless tube according to [7], wherein the melting point of each metal is 2600 ° C or more.

[10]

A method for producing a metal seamless tube according to [9], wherein the metals having a melting point of 2600 ° C or more are Mo, W and Re.

[11]

A method of producing a metal seamless pipe according to any one of [7] to [10], wherein the metal seamless pipe obtained by firing a pipe-shaped material at a lower temperature selected from a temperature range of 1000 to 2100 ° C and at a temperature 300 ° C lower than the melting point of the metal has an inner diameter of 0.4 to 3.0 mm and a thickness of 0.05 to 1.0 mm.

[12]

A method of making a metal seamless tube in accordance with any one of [7] to [11], wherein in the preparation of the mixture it is

-6 • At least one type of oxide selected from the group consisting of: the Al ₂ 0 _3, Y ₂ O 3, Dy ₂ O _3, Gd ₂ O _3,

Ho ₂ O ₃ and Tm ₂ O ₃ , in an amount of 0.02 to 5 vol% relative to 100% of the total metal and oxide volume.

[13]

A method for producing a metal seamless tube according to any one of [7] to [12], wherein the drying of the chord-shaped material is carried out in an atmosphere which: --- contains --- solvent vapors.

BRIEF DESCRIPTION OF THE DRAWINGS

Giant. 1 is a graph showing the relationship between porosity and airtightness of a metal seamless tube.

Giant. 2 sectional view schematically showing a peeling test which comprises peeling a thin W plate attached to an alumina plate using the ceramic composition of the Al ₂ 0 _{3 3} -Y20 -Dy20 -La203 _3, from the alumina plate at a given force.

Giant. 3 is a graph showing the airtightness achieved when Mo, WRe, Ti, Hf and Zr metals were used and all had a porosity of 5%.

Giant. 4 is a graph showing the relationship between thickness, inner diameter, and metal seamless airtightness

! - • · · · • •  9 • • ♦ ··· · • AND • · · AND • · · • • • · AND * · ·· «* · ·· • · ·

tubing.

Giant. 5 schematically illustrates a cross-section of a prior art construction in which a metal seamless tube is used as a sealing member of a ceramic translucent high-pressure lamp housing (e.g., metal halide lamps).

DETAILED DESCRIPTION OF THE INVENTION

In the following, preferred embodiments of a metal seamless pipe and a method for manufacturing it according to the present invention are described in more detail, with reference to the accompanying drawings.

The metal seamless pipe of the present invention comprises as its main component at least one type of metal selected from the group consisting of metals each having a melting point of 1600 ° C or more and having a porosity of 0.3 to 25%, wherein the porosity is defined as the ratio of the area of open pores that do not perforate the thickness of the tube and are located on the outer surface of the tube to the total area (100%) of the outer surface of the tube.

The metal seamless pipe of the present invention has a higher leakage reliability than the seamed pipes due to the absence of these seams. If a metal tube with seams was used as a sealing member of the translucent high-pressure lamp housing (for example, metal halide lamps), the following would be:

It is highly probable that leakage (damage) will occur, as there is a multi-atmosphere pressure inside the translucent lamp housing during operation of the lamp. As a result, the reliability of the seamed pipe is reduced compared to that of the seamless pipe.

There are no restrictions as to the type of metal whose melting point is 1600 ° C or more and which is used in the present invention. Mo (melting point 2623 ° C), W (melting point 3422 ° C), Re (melting point 3186 ° C), Ti (melting point 1668 ° C), Hf (melting point 2233 ° C) and Zr (melting point 1855 ° C), all of said metals being resistant to corrosion caused by a substance encapsulated within the interior of the translucent housing.

It should be noted that Mo and W have a centered cubic crystal structure, a high melting point, as already mentioned in the above description, and also have a very high Vickers hardness of 200 to 450. Re, Ti, Hf and Zr have closed cubic crystal structure, high melting point and have few crystalline chutes. Therefore, it is difficult to machine these metals.

In the terminology of the present invention, the term "open pores", other than through pores, means pores on the surface of the pipe that do not perforate the thickness of the pipe sheath (thus causing leakage). Similar open pores can be detected by performing a helium leak test and performing.

* · Φ

Φ Φ · ΦΦ

Analýzy φ φΦ | Μ ··· Φ · ··· Image analysis of external surface porosity.

As shown in Table 1, the airtightness is low when the porosity of the metal seamless pipe exceeds 25%.

In this document, the airtightness is measured in a helium metal tube detector, the sample of the metal seamless tube used has the following dimensions: outside diameter is large πιτη _Γ inside diameter is 0.7 mm (metal bimetal thickness is then 0.3 mm) and its the length is 100 mm. The tube samples are measured and if all 10 samples are gas-tight, the airtightness is 100%. By gas-tightness is meant the gas-tightness in the helium test, the leakage rate is 1.0 x 10 ^{* 10} atm.cc/sec. or less.

The lower limit of the porosity of the outer surface is determined by the degree of possible wetting of another substance, in particular cement, ceramics, glass or the like. A lower limit of less than 0.3% is not preferred, as shown in the results of the following tear-off test.

Tear-off test

As shown in Fig. 2, a thin W plate 3 was attached to the aluminum plate 1 using an Al ₂ 03-Y203-Dy203-La203 type ceramic compound. The thin W plate 3 was peeled from the aluminum plate 1. Breakpoints and scoring are shown in Table 1.

9 9 9 9 9 9 9 9 9 9 9 99 99 99 9 9 9

Table 1

A break point Zhodnoceni 0.1 Thin W plate surface No break of ceramics X 0.2 Thin W plate surface X —Púiuvitust- thin W plates [%] Yellows of Lus k.sFB.inLk.y 0.3 - 0.5 Thin W plate surface W ceramic plate: small Δ 1.0 W ceramic plate: small to medium Δ - o 3.0 W ceramic plate: medium 0 5.0 W ceramic plate: large 0

As shown in Table 1, the presence of the ceramic on the W plate (the remainder of the ceramic compound on the surface of the thin W plate in contact with the ceramic compound after the W plate is peeled off) shows high wettability, in other words high adhesion between the thin W plate and the ceramic compound. Therefore, a large amount of ceramic on the plate was evaluated as O. The case where there was no ceramic on the W plate was evaluated as X and the mean between them was evaluated as Δ. Thus, Table 1 shows that a porosity of less than 0.3% results in low adhesion.

If a metal with a relatively low melting point is used, the sintering is performed earlier. Specifically, it is done in ♦ * ♦ ·· · ’···

^Β * · « ^β 9 99« φ · · · · · · ···

Době * until the glue gas is released. Inside, pores are formed in large quantities and it can easily happen that these pores extend through the entire thickness of the pipe. Then, before the porosity reaches% (upper limit of the specified range), the airtightness is lower due to this phenomenon.

When Mo, W, Re, Ti, Hf and Zr are used, the gas tightness is compared by determining the porosity size to 5% for all cases. preferred metals are those having a melting point of 2600 ° C or more, in other words Mo (melting point is 2623 ° C), W (melting point is 3422 ° C) and Re (melting point is 3186 ° C).

The metal seamless pipe of the present invention preferably has an inner diameter of 0.4 to 3.0 mm and a thickness of 0.05 to 1.0 mm.

As shown in Fig. 4, leakage does not occur (and thus improved airtightness) in certain areas when the inner diameter and thickness sizes are within the above ranges.

For example, if the inner diameter is 3 mm and the thickness is 0.05 mm, the inner diameter is too large and a sufficient density increase is not achieved when sintering; leakage therefore occurs in a situation where the thickness is comparable to 0.05 mm.

If the inner diameter is 0.4 mm and the thickness is 1.0 mm, the thickness is too large and the drying speed unevenness becomes apparent when sintering; as a result, cracks occur due to uneven drying (micro-cracks), which eventually causes leakage.

Metal-made seamless pipe of the present invention preferably further contains a metal in addition to improve at least one kind oxiekí? -Zvolený · ae group -skládá jlcí? E ~ '7 ~ Al ₂ 0 _3, Y2O3, Dy2O _3, Gd ₂ O ₃ , H ₂ O 3 and Tm ₂ O 3, in an amount of 0.02 to 5 vol%, preferably 0.05 to 2 vol%, based on 100% of the total metal and oxide volume. If the amount of oxide is less than 0.02 vol%, the effect of increasing the strength is low. If the amount of oxide is greater than 5 vol%, adverse effects such as reduction of airtightness, brittleness and the like may occur. Of the above oxides, Al 2 O 3 oxide is preferred as it has good corrosion resistance.

The method of manufacturing a metal seamless tube of the present invention comprises:

- preparing a mixture comprising (1) 80 to 98 wt. a powder of at least one type of metal selected from the group consisting of metals each having a melting point of 1600 ° C or more, and (2) an adhesive in a solvent,

- agitating the mixture for 0 to 3 hours, preferably 1 to 2 hours, and then extruding the mixed material to form a tube • 9 999 · · 9 ff ♦ ··

999 • ·· ♦

99 • 8 «· ··

100 · »·

- drying the tube-shaped material at a temperature of -5 to 25 ° C (preferably 2 to 15 ° C) for a period of (at least) 10 hours to (maximum) 48 hours (preferably 24 hours) after completion of extrusion and subsequent drying at 30 to 120 ° C, preferably at 80 to 100 ^e C, for 0-8 hours, preferably 0.5 to 4 hours, and then the burning material n.qn.gpnphn - at lower --- t --- braid selected - a temperature range of 1000 to 2100 ° C, and at a temperature 300 ° C lower than the melting point of the metal.

According to the method of manufacturing a metal seamless tube, a slight drying is performed over a period of time to complete the extrusion.

This mild drying is necessary to eliminate the extrusion tension and similar phenomena occurring after the extrusion is complete (at the beginning of the drying of the particularly tube-shaped material, the drying speed is inevitably higher than the drying speed of the monolithic hollow). drying mild. Residual extrusion stress is a major cause of firing distortions and the like.

There are no restrictions on the preparation of the mixture. If at this stage the metal powder content is less than 80 wt. %, cracks may occur due to uneven drying (micro-cracks). If the metal powder content is greater than 98 wt. %, the total dispersion of the metal particles may be insufficient.

♦ · · * * * * * * * * *

Also, the mixing method and the extrusion process in the extrusion phase are not subject to any restrictions.

Also, no particular restrictions apply to the method of drying.

The firing process at the corresponding stage of the process is carried out in a non-oxidizing atmosphere or in a vacuum. The baking phase should not be sintered if the firing temperature is below a temperature selected from 1000 ° C and a temperature that is 300 ° C lower than the melting point of the metal. If the firing temperature is higher than a lower temperature selected from a temperature of 2100 ^q C and a temperature 300 ° C lower than the melting temperature of the metal, firing deformations may occur, the type and nature of which depends on the metal used.

Using a similar manufacturing process, it is possible in a simple manner to obtain a thin seamless tube with a small diameter, which would be difficult to manufacture using conventional manufacturing techniques. It is therefore possible to achieve improved productivity and, consequently, cost reduction.

The drying of the tube-shaped material is preferably carried out in an atmosphere containing the solvent vapors used in the mixture.

By using the above production method, it is possible to carry out fine drying and to reduce the occurrence of the extrusion tension.

• · · • * • * · and · • ·· ·

In the following description, the present invention is described by way of examples. However, it is to be understood that the present invention is not limited to these embodiments.

Example 1

To 1000 g of powder (melt temperature) was added, 12 g of ethyl cellulose (glue), 30 g of butylcarbitol acetate (solvent) and 10 g of dopants containing Al 2 O 3 were added. The mixture was mixed ten times in a three-roll mixing mill.

The mixture was formed in an extruder. The extruded material was dried at 80 ° C for 2 hours.

The dried material was fired with hydrogen at 1900 ° C for 3 hours. In order to remove the adhesive while preventing Mo oxidation, a dew point of 0 ° C was performed.

A Mo tube having a porosity of 8% and a leakage rate of 1.0 x 10 ¹⁰ atm.cc/sec or less was measured using a helium leak test as described above.

As already mentioned in the above description, it is possible by the present invention to produce a metal seamless pipe that is difficult to machine, but can be manufactured so that it has • 1 AVO · Φ * · ··· φ Φ · ♦?

Φ φ ··· «*

Φ Φ · ♦

♦♦ · ·· ♦♦ low thickness and small inside diameter, which is characterized by improved mechanical strength and airtightness, and which can be advantageously used, for example, as a sealing member of a translucent housing (for example a ceramic translucent housing) for a high pressure lamp (e.g. metal halides). The present invention also provides a method of manufacturing a similar metal seamless tube. The metal seamless tube according to the present invention can advantageously be used, in particular, as a sealing member of a translucent tube, for example in a high-pressure discharge lamp (for example a ceramic lamp with metal halides). Said metal seamless pipe can also be advantageously used as a metal pipe made of a poorly machined metal and with a small thickness and a small internal diameter, characterized by high heat resistance, high mechanical strength and good airtightness. An example of a possible application of such a pipe is, in particular, a fine pipe located, for example, in heat exchangers used in extreme situations and environments such as space applications, aerospace or military applications and the like.

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Claims (8)

A metal seamless tube, characterized in that it comprises as its main component at least one type of metal selected from the group consisting of metal, each having a melting point of 1600 ° C or more, the tube having a porosity of 0.3 to 25 %, where porosity is defined as the ratio of the area of open pores that do not perforate the thickness of the tube and are found sp on the outer surface of the tube to the total area (100%) of the outer surface of the tube. 2. that MO, Metallic seamless metals that W, Re, Ti, Hf pipe according to claim 1 1600 characterized by have a temperature and Zr. melting ° C or more, j sou 3. Metallic seamless tube according to claim 1 characterized by that the melting point of each metal is 2600 ° C or more. 4. Metallic seamless tube according to claim 3 characterized by that metals that have a temperature melting 2600 ° C or more, j sou Mo, W and Re. Metal seamless tube according to any one of claims 1 to 4, characterized in that its inner diameter is 0.4 to 3.0 mm and its thickness is 0.05 to 1.0 mm. The metal seamless tube according to any one of claims 1 to 5, characterized in that it further comprises at least one type of oxide selected from the group consisting of Al ₂ 0 ₃ , in addition to the metal. «·· ·· ··· Θ2θ3, Dy ₂ O ₃ , Gd ₂ O ₃ , 2ο ₂ 0 ₃ and Tm ₂ O ₃ , in quantities of 0,02 to 5% vol. % relative to 100% of the total metal and oxide volume. 7. A method of making a metal seamless tube comprising: - preparing a mixture comprising (1) 80 to 98 wt. % of a powder of at least one type of metal, especially from the group consisting of metals each having a melting point of 1600 ° C or more, and (2) an adhesive in a solvent, mixing the mixture for 0 to 3 hours and then extruding the mixed material into a tube, and - drying the tube-shaped material at a temperature of -5 to 25 ° C for (at least) 10 hours to (maximum) 48 hours after completion of the extrusion and subsequent drying at 30 to 120 ° C for 0.5 to 8 hours and thereafter firing the dried material at a lower temperature selected from a temperature range of 1000 to 2100 ° C, and at a temperature 300 ° C lower than the melting point of the metal. A method for producing a metal seamless tube according to claim 7, characterized in that the metals having a melting point of 1600 ° C or more are Mo, W, Re, Ti, Hf and Zr. 9. Method production metal seamless pipes according to claim 7 characterized by that melting temperature of each of metal Yippee 2600 ° C or more. 10. Method production metal seamless pipes according to claim 9 characterized by that metals that have a temperature melting 2600 ° C or more are Mo, W and Re, Method for producing a metal seamless pipe according to any one of claims 7 to 10, characterized in that the metal seamless pipe obtained by firing a pipe-shaped material at a lower temperature selected from a temperature range of 1000 to 2100 ° C and at a temperature of 300 ° C lower than the melting point of the metal, it has an inner diameter of 0.4 to 3.0 mm and a thickness of 0.05 to 1.0 mm. Method for producing a metal seamless pipe according to any one of claims 7 to 11, characterized in that at least one type of oxide selected from the group consisting of 21 ₂ 0 ₃ , Y ₂ O _3, Dy ₂ O _3, Gd ₂ O 3 / Ho ₂ 0 ₃ and Tm ₂ O ₃ in an amount of 0.02 to 5 vol.% relative to 100% of the total of the metal and the oxide. Method for producing a metal seamless tube according to any one of claims 7 to 13, characterized in that the drying of the tube-shaped material is carried out in an atmosphere containing solvent vapors.