JPS61204301A - Production of sintered body of heat resistant material - Google Patents

Abstract

PURPOSE:To produce a sintered body of a heat resistant material having good quality by mixing a small amt. of binder and short fibers of a synthetic resin having an adequate size with heat resistant material powder, subjecting the mixture composed thereof to injection molding and degreasing the molding then calcining the molding at a high temp. thereby degreasing easily a green compact having high strength. CONSTITUTION:A small amt. of org. binder such as wax and the short fibers of the synthetic resin having 10-40mum diameter and 0.3-2mm length are mixed with the heat resistant material powder such as ceramic raw material powder or metallic powder. The above-mentioned synthetic resin fibers made of PP, nylon, acrylic, etc. are more preferable. The above-mentioned mixture is injection-molded by a metallic mold and the injection molding is subjected to die blanking in succession thereto by which the green compact reinforced with the short fibers of the synthetic resin is obtd. without damage. The green compact is then degreased. The degreasing is easily executed as the org. binder is used in the smaller ratio. The gree compact after the degreasing is subjected to the high-temp. calcination and the sintered body of the heat resistant material having good quality without cracking, etc. is obtd.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides a method for glazing a heat-resistant material sintered body, which provides a heat-resistant powder injection-molded body with high strength and facilitates degreasing of the injection-molded body. Regarding.

(Prior art and its problems) Conventionally, products in which inorganic fibers or synthetic resin fibers are mixed as fillers in order to increase the strength of products are widely known as FRP, etc. In order to increase its strength, it is known that heat-resistant metal fibers such as steel and ceramic fibers such as silicon carbide are blended (see, for example, JP-A-59-152258).

However, these are mostly intended to increase the strength of the final product.

On the other hand, when producing a sintered body from a heat-resistant material powder, the heat-resistant material powder is first mixed with an organic binder to impart plasticity, then pressure-molded into a certain shape, and at the same time imparts strength to the pressed-formed body. give a decoy, a pilgrimage (m
J Binder Construction) LThfi - High temperature firing is performed, and the organic binders used include resins such as polypropylene and polyethylene, as well as paraffin and wax. However, the amount of such organic binder mixed is considerable (sometimes up to 30% by weight), so degreasing takes a long time, and the compact after degreasing has a low density, resulting in a fired product. I can't get anything of good quality either.

By the way, when a synthetic resin material such as polyethylene or polypropylene is used as an organic binder, the strength of the pressure-molded body (green body) increases and the number of accidents in which the green body is damaged when taken out from the mold is reduced. In the degreasing process, it is difficult to decompose (<
However, if paraffin or wax is used, degreasing can be done well, but the strength of the green material is low ( In particular, it is difficult to remove products with complex shapes from the mold.

Therefore, there has been a long-awaited demand in the industry for a green body that is strong and easy to degrease.

(Means for Solving the Problem) The present invention has been made in view of the above, and according to the present invention, the strength of the green body can be increased even though the amount of organic binder is significantly reduced. Therefore, degreasing is easy, and baked products of good quality can be obtained.

Specifically, the present invention involves mixing a small amount of organic pineapple and short synthetic resin fibers with a diameter of 10 to 40/7 m and a length of 0.3 to 2 cm into a heat-resistant material powder, and then injection molding the mixture in a mold. The method for producing a heat-resistant material sintered body is characterized in that the injection-molded body is subsequently cut out, and then the molded body is degreased and then fired at a high temperature.

In the present invention, by mixing an organic binder and short synthetic resin fibers with the heat-resistant material powder, not only the strength of the green body is increased (but also degreasing treatment can be carried out easily).

If the synthetic resin fiber is thin, it will not be thoroughly mixed into the heat-resistant material powder, and the edges of the green body will be weak (and may break when released from the mold, or may be damaged in the degreasing furnace). The green body may be cracked or chipped before it is transported to the factory.Furthermore, if the green body is short in diameter, such as fine particles, the reinforcing effect will not be exhibited.

Therefore, it is necessary that the fibers have a size that allows them to be easily and sufficiently mixed with the heat-resistant material powder and can be used as a reinforcing material, and as a result of experiments, it is preferable that the fibers have a diameter of 10 to 40 .mu.11 and a length of 0.degree. to 3 to 2 mm.

In addition, the melting point of the miscellaneous material must be higher than that of the binder, since if it melts together with the organic paint during heat molding, it cannot serve as a reinforcing material for the molded product. .

Furthermore, it is preferable that the fibers decompose and disappear during the degreasing process, and should not remain undecomposed in the fired body during high-temperature firing.

Suitable fibers meeting the above conditions are those made of synthetic resin, particularly polypropylene, nylon, and acrylic resin.

(Example) After adding a low melting point organic binder such as wax or paraffin to heat-resistant material powder such as ceramic raw material powder or metal powder to give fluidity, short fibers such as polypropylene or nylon are further added to form a mixture. I built it.

Next, the mixture is heated within a temperature range where the short fibers do not melt and the organic binder flows (in the case of polypropylene, 80 to
When injection molding is carried out at 120℃), fJ is formed inside the green body.
As shown in Figure S1 (B) (partially enlarged view of the green body), the fibers are arranged substantially uniformly along the supply flow direction of the mixture in the mold.

In the figure, 1 is a green body, 2 is a heat-resistant material particle, 3 is an organic binder, and 4 is a synthetic resin short fiber.

Moreover, FIG. 2 shows a conventional example in which short synthetic resin fibers are not blended.

An example in which a green body was manufactured by injection molding using alumina powder and silicon nitride powder will be given below.

Example 1: Add paraffin (melting point 50 to 7) to 100 parts by weight of alumina powder.
0°C) 15 parts by weight, polypropylene fiber (diameter 20-3
0 μm 1 length 0.5 to 1 m + e) 5 parts by weight were added and mixed, and the mixture was injection molded in a mold at 70 to 90°C.

Example 2: 100 parts by weight of silicon nitride powder and polyethylene (melting point 105
℃) 18 parts by weight, acrylic fiber (diameter 20-30 μm,
Add and mix 5 parts by weight (length 0.5 to lll111),
This was injection molded in a mold at 120-150°C.

The green body according to Example 1.2 has greatly improved strength compared to conventional products without the addition of short synthetic resin fibers, and when taking out the molded product from the mold during injection molding, it will not be damaged by the ejector turbine. There was no.

(Effects of the Invention) As described above, according to the present invention, the amount of organic binder added can be extremely reduced, making it easy to degrease green bodies. Since the strength of the green body has been greatly improved, there is no chance of the green body being damaged when it is removed from the mold by an ejector turbine.

Normally, the amount of bangu used should be kept as small as possible since degreasing is not easy. However, if it is too small, not only will the green body have insufficient fluidity during molding, but the green body will become brittle and easily damaged during handling ( Therefore, there was naturally a certain limit to reducing the amount of organic pine goo in the past.

However, in the present invention, by adding synthetic 11w short fibers, the conventional limitations have been overcome and it has become easier to produce a high quality heat-resistant material sintered body.

Furthermore, in the degreasing treatment (debinding treatment) of the green body taken out from the mold, there is no risk of cracking in the green body even if the temperature of the green body is rapidly raised to near the boiling point of the organic binder, so conventional methods are used. It has the great advantage of being able to degrease in about two-thirds of the time.

In the conventional method, when the temperature is rapidly raised to near the boiling point of the organic binder in an attempt to shorten the degreasing time, cracks occur in the green body due to the vaporization expansion pressure of the organic binder, so it is necessary to degrease with a low temperature increase gradient. Therefore, a long degreasing time was required, but in the present invention, the green body is reinforced with synthetic resin mt staple fibers, so even if the green body is subjected to rapid temperature degreasing treatment, no cracks occur in the green body.

[Brief explanation of the drawing]

FIG. 1 shows the shape (A) of a green body according to an embodiment of the present invention and an enlarged partial sectional view thereof, and FIG. 2 shows a conventional example. 1: Nigel integrally, 2: thermal material powder particles, 3: organic binder, 4: synthetic resin short fiber Patent applicant: Sumitomo Heavy Industries, Ltd. Figure 1 Figure 2

Claims (4)

[Claims] (1) Heat-resistant material powder with a small amount of organic binder and diameter 1
After mixing synthetic resin short fibers with a length of 0 to 40 μm and a length of 0.3 to 2 mm, the mixture was injection molded in a mold, the injection molded body was subsequently cut out, and the molded body was then degreased. A method for producing a heat-resistant material sintered body, which is then fired at a high temperature. (2) The method for producing a heat-resistant material sintered body according to claim 1, wherein the short synthetic resin fibers are made of polypropylene. (3) The method for producing a heat-resistant material sintered body according to claim 1, wherein the short synthetic resin fibers are made of nylon. (4) The method for producing a heat-resistant material sintered body according to claim 1, wherein the synthetic resin short fibers are made of acrylic.