JPS6316465B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing an electron beam heating crucible used for electron beam heating evaporation and the like.

[Prior art]

FIG. 1 is a principle diagram showing an outline of a general electron beam heating vapor deposition apparatus. Electron beam heating evaporation is
The filament 2 is heated in the container 1 which is evacuated by the exhaust system 1a, and a high voltage of several tens of kV is applied between the copper crucible 4 containing the evaporation source 3 and the substrate 5 to be evaporated. The generated electrons are accelerated and irradiated onto the evaporation source 3, and the evaporation source 3 is heated and evaporated to form a deposited film 6 on the surface of the substrate 5. In such an apparatus, the crucible 4 and the insulator 7 are water-cooled because the crucible 4 itself must not melt and the bond between the crucible 4 and the insulator 7 must not separate. Therefore, a considerable amount of the heat applied to the evaporation source 3 escapes through the evaporation source 3 and the crucible 4, and the amount of heat effective for evaporation decreases. In this way, the evaporation efficiency with respect to the applied electric power becomes small, and this tendency is particularly strong for materials with good thermal conductivity such as copper, silver, and aluminum.

Therefore, as a means to improve evaporation efficiency, crucible 4
In order to insulate the space between the evaporation source 3 and the evaporation source 3, it is conceivable to heat the evaporation source 3 by placing it in an electron beam heating crucible 8 made of ceramic with excellent heat insulation properties. In this case, even if the crucible 8 made of ceramics, which is an insulator, is used, a discharge is generated between the crucible 8 and the evaporation source 3 over the ceramic wall, and high voltage can be applied to the evaporation source 3. It is desirable that the crucible 8 used for the above purpose be made of a material that is heat resistant, has a high melting point, is resistant to heat shock, and is inexpensive.

A conventional manufacturing method for the crucible 8 is to press-form ceramic powder and fire it, but since the crucible manufactured by this method is a fired product, it has a dense structure and is susceptible to heat shock, making it difficult to use for electron beam heating. When used for this purpose, it often cracks and is not suitable for practical use.

Another conventional manufacturing method includes a method of manufacturing by thermal spraying ceramics. FIG. 2A is a sectional view showing a conventional manufacturing method, B is a sectional view of the manufactured crucible, and C is a perspective view thereof.The method of manufacturing the crucible 8 is as shown in FIG. From step 9, ceramic powder 10 such as zirconia (ZrO ₂ ) or alumina (Al ₂ O ₃ ) is thermally sprayed onto a crucible-shaped mold 11 to form a ceramic thick film 12 , and then the mold is released to form a crucible 8 . This is a method of manufacturing. The crucible 8 manufactured by this method has many pores in the ceramic thick film 12, which is a characteristic of thermally sprayed films, and is therefore resistant to heat shock.

However, in such a conventional method of manufacturing the crucible 8 by thermal spraying, zirconia, alumina, etc. are directly sprayed onto a mold made of metal or ceramics, so the heat between the ceramic thick film 12, which is the thermal spraying material, and the mold 11 is Due to the difference in expansion and the self-bonding force of ceramic particles during film formation, the ceramic thick film 12 often peels off or cracks from the mold 11 during thermal spraying, and cracks occur during demolding, resulting in a crucible shape. It was difficult to mold.

[Summary of the invention]

This invention was made with the aim of improving the above-mentioned drawbacks.
By thermally spraying 80μm boron carbide (B ₄ C) powder to form a film, and then thermally spraying heat-resistant crucible material on top of it to form a composite thick film, it is resistant to heat shock, easy and inexpensive. This paper proposes a method for manufacturing a crucible for electron beam heating that can be manufactured in a number of steps.

[Embodiments of the invention]

Embodiments of the invention will be described below with reference to the drawings. 3A and 3B are cross-sectional views showing a manufacturing method according to an embodiment of the present invention, C is a cross-sectional view of a manufactured crucible,
D is a perspective view thereof. The manufacturing method is first shown in Figure 3A.
A metal mold 11 having the desired crucible shape shown in
is rotated, and boron carbide powder 13 is thermally sprayed to a thickness of about 50 μm on the surface by plasma spraying device 9 to form a boron carbide film 14 as a first layer. Next, a ceramic powder 10 such as zirconia or alumina suitable for a crucible material is thermally sprayed onto the boron carbide film 14 to a desired thickness to form a second layer of ceramic thick film 1.
2 to form a composite thick film 15 as a whole. Thereafter, the composite thick film 15 is released from the mold 11 to obtain the crucible 8. Here, the particle size of the boron carbide powder 13 is preferably 10 to 80 μm. If the particle size is extremely small,
The boron carbide powder 13 has poor penetration into the mold 11;
In addition, the self-bonding between sprayed particles is too strong, resulting in peeling and cracking during spraying. Furthermore, if the particle size is too large, it will be difficult to melt and the film formation efficiency will deteriorate. The thickness of the boron carbide film 14 to be formed is
A thickness of 30 μm or more is sufficient. The thermal spraying conditions for the ceramic powder 10 are as follows: zirconia powder with a particle size of 10 to 100 μm is used, a mixed gas of nitrogen and hydrogen is used as the plasma gas, and the applied voltage is DC.
75V, current is 500A, plasma spray equipment 9 and type 1
The distance of 1 is 10cm. Particle size for alumina
Powder of 15 to 55 μm was used, and other conditions were almost the same as in the case of zirconia. It is also possible to use a mixed gas of argon and hydrogen as the plasma gas. Regarding the spraying conditions for boron carbide, the distance between the plasma spraying device 9 and the mold 11 was 15 cm, and the other conditions were almost the same as those for zirconia and alumina. The thicker the ceramic thick film 12, such as zirconia, as the crucible material, the stronger it will be mechanically, and can be adjusted as necessary.

In this way, by thermally spraying the boron carbide powder 13 onto the mold 11 and then thermally spraying the ceramic powder 10 such as zirconia or alumina, an appropriate surface roughness is generated on the mold 11 during the thermal spraying of the boron carbide powder 13, resulting in carbonization. Appropriate adhesion can be obtained between the boron film 14 and the mold 11. Since there are irregularities on the surface of the boron carbide film 14, the ceramic thick film 12 sprayed thereon is strongly bonded to the boron carbide film 14. Further, the pores in the boron carbide film 14 and the ceramic thick film 12 absorb heat shock during thermal spraying. Therefore, the crucible 8 can be easily manufactured without peeling or cracking during thermal spraying and demolding. The obtained crucible 8 has the boron carbide film 14 on the inside, that is, on the side that contacts the evaporation source 3,
If the reaction with boron carbide is undesirable, the boron carbide film 14 can be removed by mechanically scraping it off after the crucible 8 is manufactured or by heating it in an oxidizing atmosphere.

FIG. 4A is a sectional view showing a manufacturing method according to another embodiment, B is a sectional view of the manufactured crucible, and FIG. 4C is a perspective view thereof. This manufacturing method uses a concave mold 11, and after spraying a boron carbide film 14 on the first layer,
If a ceramic film 12 such as zirconia or alumina is formed as the second layer, there will be no reaction with the evaporation source 3, and since boron carbide has low electrical resistance, conduction between the crucible 4 and the surrounding area of the crucible 4 will be improved. Discharge can be reduced.

In the above embodiment, the material of the mold 11 is metal, but it is also possible to use ceramics, and the mold 11 can be used repeatedly by slightly polishing the surface. If the mold 11 has a slight draft taper, mold release can be easily performed. In addition, although examples of ceramics such as zirconia or alumina have been shown as crucible materials, other crucible materials such as platinum, tungsten, and molybdenum may also be used, and boron carbide itself can also be used as the crucible material, and in these cases, zirconia, alumina, etc. Thermal spraying can be carried out under almost the same conditions as in the case of .

[Effects of the Invention] As described above, according to the present invention, a small amount of boron carbide is sprayed onto a crucible-shaped mold, and then the crucible material is sprayed to form a composite thick film and the mold is released. There is no peeling or cracking during thermal spraying or mold release, and it is possible to easily and inexpensively manufacture crucibles for electron beam heating.The manufactured crucibles contain many pores, so they can absorb thermal strain and are heat-resistant. It has the effect of being resistant to shock and can be used for a long time.

[Brief explanation of the drawing]

Fig. 1 is a principle diagram showing the outline of a general electron beam heating evaporation device, Fig. 2 A is a sectional view showing a conventional manufacturing method of an electron beam heating crucible, B is a sectional view of the manufactured crucible, and C 3A and 3B are cross-sectional views showing a manufacturing method according to one embodiment of the present invention, C is a cross-sectional view of the manufactured crucible, D is a perspective view thereof, and FIG. 4 A is another embodiment. A cross-sectional view showing a manufacturing method according to an example, B is a cross-sectional view of the manufactured crucible, and C is a perspective view thereof. In the figure, 1 is a container, 2 is a filament, 3
1 is an evaporation source; 4 and 8 are crucibles; is a composite thick film. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. Boron carbide powder with a particle size of 10 to 80 μm is sprayed onto a mold having a crucible shape by plasma spraying to form a film, and then a heat-resistant crucible material is further sprayed on top of the film to form a film with a composite thickness. A method for manufacturing a crucible for electron beam heating, characterized by forming a film and then releasing the mold. 2. The method for manufacturing an electron beam heating crucible according to claim 1, wherein the mold is made of metal or ceramics. 3. The method for manufacturing a crucible for electron beam heating according to claim 1 or 2, wherein the crucible material is zirconia or alumina. 4. The method for manufacturing a crucible for electron beam heating according to any one of claims 1 to 3, wherein the boron carbide film is formed on the inside or outside of the crucible.