JPH07315935A - Production of electric conductive ceramic sintered compact - Google Patents

Abstract

PURPOSE:To produce an electric conductive ceramic sintered compact capable of producing a heating element (boat) for evaporating a metal having a long service life. CONSTITUTION:A powdery mixture contg. boron nitride powder contg. pyrolytic boron nitride, titanium diboride powder and aluminum nitride powder is compacted and sintered in a nonoxidizing atmosphere to produce the objective electric conductive ceramic sintered compact used for producing a heating element for evaporating a metal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a conductive ceramics sintered body suitable for producing a metal-evaporating heating element which is used particularly when vaporizing a metal in a vacuum.

[0002]

2. Description of the Related Art Conventionally, as a heating element for metal evaporation of this type, for example, there is a boat made of conductive ceramics having a cavity as shown in Japanese Patent Publication No. 53-20256. The product name is "BN Composite EC" manufactured by Denki Kagaku Kogyo. The method of using this is to connect both ends of the boat with clamps to the electrodes to apply a voltage to generate heat, and melt and evaporate the metal contained in the cavity to obtain a vapor deposition film.

[0003]

[Problems to be Solved by the Invention]
As the number of times of use increases, the boat is melted and damaged by the molten metal, and the resistance gradually increases, so that the vapor deposition film becomes thin and the life of the boat becomes long. When the metal is aluminum, the average life is about 500 times. An object of the present invention is to provide a method for producing a conductive ceramics sintered body that can extend the life of the boat.

[0004]

According to the present invention, a molded product of a mixed powder containing a boron nitride powder containing pyrolytic boron nitride, a titanium diboride powder and an aluminum nitride powder is treated under a non-oxidizing atmosphere. And a method for producing a conductive ceramics sintered body, characterized in that the conductive ceramics sintered body is for producing a heating element for metal evaporation. It is a method for producing a conductive ceramics sintered body.

The present invention will be described in more detail below. The feature of the present invention is that a mixed powder containing a hexagonal boron nitride powder, a titanium diboride powder and an aluminum nitride powder is molded, and the mixed powder is subjected to a non-oxidizing atmosphere. That is, in the conventional method of sintering at, the boron nitride powder containing pyrolytic boron nitride was used as the hexagonal boron nitride powder.

In the present invention, the ratio of the pyrolytic boron nitride in the boron nitride powder containing the pyrolytic boron nitride is 50.
It is preferably at least wt% (including 100 wt%), and if it is less than 50 wt%, the corrosion resistance to molten metal is not sufficiently improved and the boat life extension effect is small. Pyrolytic boron nitride is produced by supplying boron trichloride and ammonia to a chemical vapor deposition chamber for thermal decomposition and precipitation on the surface of a graphite substrate, as described in, for example, Japanese Patent Publication No. 4-56765. can do.

Boron nitride powder containing pyrolytic boron nitride,
An example of the ratio of each component of the mixed powder containing the titanium diboride powder and the aluminum nitride powder is as follows. Boron nitride powder containing pyrolytic boron nitride 15 to 50% by weight, titanium diboride powder 30 ˜60 wt% and aluminum nitride powder 10-45 wt%. If the content of the boron nitride powder containing pyrolytic boron nitride exceeds 50% by weight, the corrosion resistance to the molten metal decreases, and if it is less than 15% by weight, the thermal shock resistance becomes insufficient. On the other hand, when the aluminum nitride powder exceeds 45% by weight, the thermal shock resistance is lowered, and when it is less than 10% by weight, the strength is insufficient. The particle size of the mixed powder is preferably 20 μm or less, particularly 10 μm or less.

The sintering of the mixed powder is preferably a hot press sintering method, but may be an atmospheric pressure sintering method, a HIP sintering method or the like. In the hot press sintering method, the mixed powder is filled in a graphite die, and the temperature is about 1700 to 2000 ° C. and the pressure is 50 to 350 Kg / in a non-oxidizing atmosphere such as argon and nitrogen.
It is performed at about cm ² .

In order to manufacture a heating element for metal evaporation from the obtained conductive ceramics sintered body, a molded body having an appropriate shape is cut out from the sintered body by a conventional method, and a cavity is formed in the center thereof. It can be carried out.

[0010]

【Example】

Examples 1 to 6 Comparative Example 1 TiB ₂ powder (average particle size 12 μm), hexagonal boron nitride (hBN) powder (average particle size 0.7 μm), commercially available pyrolytic boron nitride (PBN) pulverized product The substance (average particle diameter 30 μm) and AlN powder (average particle diameter 10 μm) were mixed at the ratio shown in Table 1. The obtained mixed powder was filled in a graphite die and hot pressed at a temperature of 1750 ° C. to manufacture a sintered body having a diameter of 200 mm and a height of 6 mm.

From this sintered body, width 6 mm × thickness 4 mm ×
A rod-shaped body having a length of 110 mm was cut out, and a cavity having a width of 4 mm, a depth of 2 mm and a length of 60 mm was processed in the center of the surface of the rod-shaped body to produce a metal evaporation heating element (boat).

In order to evaluate the life of the obtained boat, the applied voltage was determined and set so that the temperature at the center of the cavity was 1500 ° C. by connecting the end of the boat to the electrode with a clamp. Aluminum amount of 80mg per time, energizing time 30
Second, the vapor deposition test was performed at a vacuum degree of 2 × 10 ⁻⁴ torr,
This operation was repeated at the set constant applied voltage.
The boat life was defined as the number of repetitions when the thickness of the aluminum vapor deposition film at a position 200 mm above the boat became 2000 A or less. The results are shown in Table 1.

[0013]

[Table 1]

[0014]

According to the present invention, it is possible to manufacture a conductive ceramics sintered body capable of producing a metal evaporation heating element (boat) having a long life even if metal evaporation is repeatedly performed.

Claims (2)

[Claims] 1. A molded product of a mixed powder containing a boron nitride powder containing pyrolytic boron nitride, a titanium diboride powder and an aluminum nitride powder is sintered in a non-oxidizing atmosphere. A method for producing a conductive ceramics sintered body. 2. The method for producing a conductive ceramics sintered body according to claim 1, wherein the conductive ceramics sintered body is for producing a heating element for metal evaporation.