JPS613804A - Raw material sheet for sintered metallic body and its production - Google Patents

Abstract

PURPOSE:To obtain a raw material sheet for a sintered metallic body with the smaller amt. of the binder to be used by inserting a resilient fine wire-shaped reinforcing body between the two sheets obtd. from the kneaded mixture composed of sinterable metallic powder and resin binder and sticking each other. CONSTITUTION:The synthetic resin binder is mixed with a powder mixture composed of self-fluxing Ni alloy powder and Mo powder, etc. and is kneaded. The mixture is subjected to rolling, etc. by which a sheet-shaped material is obtd. The fine wire-shaped reinforcing body R having resilience, for example, carbon fibers braided to a net shape are inserted between the two sheets S1 and S2 obtd. in such a manner and the sheets are passed through a rolling mill M to adhere the sheets S1, S2. The raw material sheet for the sintered metallic body having a good handling characteristic, resistance to crazing and fitness is easily obtd. by the above-mentioned method.

Description

DETAILED DESCRIPTION OF THE INVENTION A1 Object of the Invention (1) Field of Industrial Application The present invention relates to a raw material sheet for metal sintered bodies and a method for producing the same.

(2) Prior art The applicant first attached a raw material sheet for a metal sintered body obtained from a kneaded mixture of sinterable metal powder and a synthetic resin binder to a metal base material, and then attached the raw material sheet to a metal base material. We have proposed a technique in which a sintered body is obtained by sintering the molded body after being formed into a predetermined shape, and at the same time, the sintered body is welded to a base material.

(3) Problems to be solved by the invention In the above-mentioned raw material sheet, 1 to 10% by weight of a synthetic resin binder is mixed with the metal powder in consideration of ease of handling when pasting it to a base material. Because of this, a large amount of binder is used. This binder is thermally decomposed, gasified, and removed from the sintered body in the sintering process, but if the amount of binder used is large, the porosity of the sintered body increases accordingly, which is not preferable in terms of strength.

In view of the above, an object of the present invention is to provide the raw material sheet and a method for manufacturing the same, which can reduce the amount of binder used.

B1 Structure of the Invention (]) Means for Solving the Problems The raw material sheet for metal sintered bodies according to the present invention contains, in a sheet-like material obtained from a kneaded product of sinterable metal powder and a synthetic resin binder, It is characterized by having thin, flexible reinforcing bodies dispersed and buried in holes.

In addition, the method for producing a raw material sheet for a metal sintered body according to the present invention includes a method for producing a raw material sheet for a metal sintered body from a kneaded product of a sinterable metal powder and a synthetic resin binder.
It is characterized by using a step of obtaining two sheet-like objects, and a step of bonding the two sheet objects together by interposing thin, flexible reinforcing bodies in a dispersed manner between them.

(2) Function The raw material sheet has flexible fine wire reinforcing bodies dispersed and buried therein, so it has good handling properties, crack resistance, and conformability, and these properties are improved by the use of a synthetic resin binder. Even if the amount is reduced to half of the conventional one, there will be no loss.

Moreover, since the raw material sheet is obtained by dispersing and inserting the thin linear reinforcing body between two sheet-like materials and bonding the two sheet-like materials together, the manufacturing operation is extremely easy.

(3) Examples Examples of flexible thin wire reinforcing bodies used in the present invention include metal fibers such as stainless steel fibers, carbon fibers, thin wires made of synthetic resin, thin wires made of metal such as copper, etc. It can be used as is or organized into a net.

FIG. 1 shows a raw material sheet St, which is a sheet material S obtained by kneading sinterable metal powder and a synthetic resin binder.
The thin wire reinforcing bodies R are knitted into a net shape and buried in the inside.

The raw material Sea+-St is produced by the method described below.

Ni self-fusing alloy powder 80% by weight and Mo pulverized powder 2
0% by weight are sufficiently mixed in a blender to obtain a mixed powder, and a synthetic resin binder is obtained by mixing a tetrafluoroethylene resin emulsion and an acrylic resin emulsion at a ratio of 1:1.

Add 1.6% by weight of a synthetic resin binder to the above mixed powder and thoroughly knead it using a bench kneader.
The water in the synthetic resin binder is evaporated by heating to 00 to 150°C. The obtained kneaded product has a shape of numerous nodules due to being caked by the synthetic resin binder.

The above-mentioned kneaded material is heated to 80 to 100[deg.] C. and passed through a roll machine multiple times to obtain a 6 tar sheet-like material.

In this case, if the rolls of the roll machine are heated to the same degree as the kneaded material, the sheet forming operation can be easily performed.

The sheet material was cut into two pieces, and as shown in FIG. Both sheet materials SI+32 are pasted together through a roll machine M.

Through the above steps, a raw material sheet SL having a thickness of 3.0 fi is obtained. When the fine wire reinforcements R are knitted in a net shape in this way, the handling properties are good, so the production of the raw material sheet St can be carried out easily, and the fine wire reinforcements R are knitted in the raw material sheet St.
is uniformly dispersed, so it is possible to obtain a raw material sheet St with uniform compatibility throughout. Conventionally, when producing a raw material sheet having the same thickness as this raw material sheet, approximately 3% by weight of a synthetic resin binder is added to the mixed powder, but in the present invention, the amount of binder used is approximately halved. I can do it.

Next, the third. A method for manufacturing a press mold using the raw material sheet st will be described with reference to FIG. 4.

As shown in FIG. 3(a), the base material 1 is cast steel (Jr.
The base surface 1a forming the workpiece molding part is formed to be 5 to 20 centimeters lower than the outer surface of the workpiece molding part (indicated by chain lines) in the completed mold. .

Since the base material 1 is used as-cast, an acrylic resin adhesive is applied to the base surface 1a having a black crust after cleaning. As shown in FIG. 3(b), the raw material sheets st are laminated and pasted on the base surface 1a, and the laminated raw material sheets St are pressed by a synthetic resin mold MO to form a workpiece molding part.

The work of pasting the raw material sheet St described in = is easy because the sheet 3t has good handling and conformability, and the raw material sheet S has excellent crack resistance, so the sheet surface after molding is is smooth.

As shown in FIG. 3<c>, the base material 1 is placed in a container 2, the surface of the laminated raw material sheet St is covered with ceramic powder, and a steel ball 3 with a diameter of 0.7.5n is poured into the container 2. Perform bank up with . Depending on the weight of this steel ball 3, Ni
This suppresses the dimensional change, that is, expansion, of the sintered body during sintering of the self-fusing alloy-MO powder.

Next, the container 2 is placed in a vacuum sintering furnace 4, and the organic substance is decomposed and the metal powder is sintered under the heating-cooling conditions shown in FIG. As the carrier gas, nitrogen gas or highly reducing hydrogen gas is used.

(A) First heating zone (Fig. 4A) This heating zone A is from room temperature to 650°C, and the temperature increase rate is 10~b. In the heating zone A, water first evaporates, then the four Fufluorinated ethylene resin and acrylic resin decompose and gasify. These synthetic resins have a temperature of 300 to 400℃
However, in consideration of heat conduction, most of the organic substances are removed by soaking at 600 to 650° C. for 90 minutes, and the Ni self-soluble alloy-Mo powder remains. The gasification of this organic substance can be explained by the change in the degree of vacuum inside the vacuum sintering furnace 4.
At room temperature, it is I TOrr, but when soaked at 650°C for 90 minutes, the degree of vacuum decreases to a maximum of 2'l''orr. This is mainly due to the generation of decomposed gas of organic substances. After that, the vacuum level is set to ITorr again.
This means that the cracked gas is removed from the vacuum sintering furnace 4.

(B) Second heating zone (Fig. 4B) This heating zone B is in the range of 900 to 1000°C,
Ni self-fusing alloy-Mo powder body is heated at a temperature below the solidus line (1010 to 1020°C) of the Ni self-fusing alloy, for example 950°C.
A solid phase sintering process is performed by soaking and holding for 30 minutes, and this is pre-sintered. The temperature increase rate from the first heating zone 8 is 10~b.

Since the Ni self-fusing alloy-Mo powder body in the vacuum sintering furnace 4 is heated from its surface and increases in temperature, a predetermined heating time is required until the entire powder body reaches a uniform temperature. If it is suddenly heated to the sintering temperature of 1000-1200℃, a temperature difference will be created between the surface part of the Ni self-fusing alloy-Mo powder and the part in contact with the base surface, which will increase the variation in porosity and make it uniform. Not only is it impossible to obtain a sintered body, but also defects such as cracks are likely to occur after sintering.

In the second heating zone B, undecomposed organic substances are completely gasified and removed. Due to this gasification, etc., the degree of vacuum in the vacuum sintering furnace 4 temporarily decreases to 4 Torr, but returns to I Torr after 30 minutes.

(C>Third heating zone (Fig. 4C)) This heating zone C is located at the solidus line (101
0~1020℃) to just below the liquidus line (1075~1085℃)
℃), i.e. in the range of 1000 to 1200℃, and the Ni self-fusing alloy-Mo pre-sintered body is kept at a constant temperature of 1100 to 1180℃, preferably 1160℃, which is a temperature exceeding the liquidus line, for 120 minutes. While holding the Ni self-fusing alloy, a liquid phase sintering process is performed by melting the Ni self-fluxing alloy to form a sintered body. In this case, the flow of the Ni self-fusing alloy is hindered by the presence of MO, and therefore shape retention is good. The temperature increase rate from the second heating zone B is 15~b, and the Ni self-fluxing alloy-Mo pre-sintered body is
Since it has already been heated to a high temperature, the time required to raise the temperature to the third heating zone C is short. If the holding time in the third heating zone C is insufficient, sintering will not be completed completely, resulting in defects in the sintered body.

The reason for selecting the sintering temperature at 1160℃ as mentioned above is
When the sintering temperature is about 1200℃, the dimensional change of the sintered body becomes large, and the furnace temperature I+IJlill is difficult to adjust (
Moreover, there is a problem that the temperature inside the furnace fluctuates, and the working temperature to eliminate these problems is 116.
This is because 0°C is appropriate.

(D) Cooling zone (Fig. 4D) This cooling zone D consists of a primary cooling zone D from the sintering temperature to about 8°C, and a cooling zone D from about soo'c to about 400°C.
The cooling zone is divided into a secondary cooling zone D2 ranging from approximately 400° C. to room temperature, and a tertiary cooling zone D ranging from approximately 400° C. to room temperature.

The primary cooling zone D1 is a stable region of the sintered body under high temperatures, and in this cooling zone D, thermal stimulation is avoided as much as possible, and at the same time, the cooling rate is slow at a maximum of about 2°C/min in consideration of cooling efficiency. Cool it down. When rapid cooling is performed in this cooling zone DI, cranks occur frequently in the sintered body.

In the secondary cooling zone D2, linear expansion of the base material l and Ar,
Cool at a slow rate of up to 3° C./min to accommodate dimensional changes during transformation.

In this case, the linear shrinkage of the sintered body is 14.6 x 10-'/'
c, but since it is porous, it follows the shrinkage of the base material 1. When rapid cooling is performed in this cooling zone D2, cranks occur frequently in the sintered body.

In the tertiary cooling zone D, the temperature of the sintered body and the base material 1 is cooled to room temperature by gas cooling (including air cooling) other than liquid cooling such as water or oil.

As shown in FIG. 2(e), through the heating and cooling process described above, a mold 5 is obtained in which the workpiece forming portion 5a is formed of a sintered body Sa made of Ni self-fluxing alloy-Mo.

The sintered body Sa has good weldability and surface roughness with the base material 1, and has a low porosity. Furthermore, there is no occurrence of defects such as cranks, and the dimensional change is accurate within ±θ to +2fi, so it can be used for press work immediately after simple finishing.

The carbon fiber linear reinforcement R between the raw material sheets is a sintered body S
It remains in the sintered body Sa, and the strength of the sintered body Sa can be improved by the fiber reinforcing ability of the reinforcing body R.

This fiber reinforcing ability can be similarly obtained when metal fibers such as stainless steel fibers are used.

When copper 411rlIa is used as the linear reinforcement, the thin wire melts during the sintering process and fills the pores of the sintered body.
It has the effect of improving its strength.

When a synthetic resin thin wire is used as the linear reinforcing body, the thin wire is thermally decomposed together with the synthetic resin binder, gasified, and removed from the sintered body.

Note that the bonding operation of both sheet-like materials S+ and Sz can also be performed using a press machine having a hot plate.

C1 Effects of the Invention The raw material sheet for metal sintered bodies according to the present invention has flexible fine wire reinforcing bodies dispersed and buried therein, so that it has good handling properties, crack resistance, and conformability. The properties are not impaired in any way even if the amount of synthetic resin binder used is reduced to half of the conventional one.

Further, the method for manufacturing a raw material sheet for a metal sintered body according to the present invention employs a simple method of dispersing the thin wire reinforcing body between two sheet-like materials and bonding both sheet-like materials. This makes manufacturing work extremely easy.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a perspective view of a raw material sheet with main parts cut away, FIG. 2 is an explanatory diagram showing the production of the raw material sheet, and FIG. Fig. 4 is a graph showing the relationship between temperature and time in the sintering process.R: Fine wire reinforcement, So, S+ , Sz... sheet-like material, Sa... sintered body Fig. 3 Fig. 1 Fig. 2 Fig. 4 Time

Claims (7)

[Claims] (1) A raw material sheet for a metal sintered body, which is made by dispersing and embedding flexible thin wire reinforcing bodies in a sheet-like material obtained by kneading a sinterable metal powder and a synthetic resin binder. (2) The raw material sheet for a metal sintered body according to claim (1), wherein the thin wire reinforcing body is made of metal fiber. (3) The raw material sheet for a metal sintered body according to claim 1, wherein the thin wire reinforcing body is made of carbon fiber. (4) The raw material sheet for a metal sintered body according to claim (1), wherein the thin wire reinforcing body is made of synthetic resin. (5) The raw material sheet for a metal sintered body according to claim (1), wherein the thin wire reinforcing body is made of a thin metal wire. (6) a step of obtaining two sheet-like products from a kneaded product of sinterable metal powder and a synthetic resin binder;
A method for manufacturing a raw material sheet for a metal sintered body, which comprises the steps of: dispersing and laminating flexible fine wire reinforcing bodies between them; (7) The method for producing a raw material sheet for a metal sintered body according to claim (6), wherein the thin wire reinforcing bodies are knitted in a net shape.