JPH0361304A - Composite material manufacturing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to heat-resistant materials for spacecraft and electronics,
The present invention relates to a method for manufacturing a composite material that can be used as a device material, etc., which has a large temperature difference between its front and back surfaces depending on the environment in which it is used.

[Conventional technology]

The powder method is the cheapest method for manufacturing composite materials made of ceramics and metals and allows for mass production. The powder method is a method in which ceramic and metal powders are mixed in a ball mill or the like, molded, and then fired.

Since the composition of the sintered body made by this method can be varied over a wide range, it is possible to design and manufacture composite materials depending on the purpose and use.

However, although such a composite sintered body has excellent heat resistance properties, it is weak in bending strength and may be destroyed by stress caused by a temperature difference between the front and back surfaces in the usage environment. Furthermore, even in extremely harsh high-temperature environments where the material must be forcibly cooled from the back side, the low heat transfer coefficient unique to ceramic sintered bodies prevents the cooling efficiency from being fully utilized. There are also problems.

The composition ratio was changed to alleviate the stress generated within the material due to the temperature difference between the front and back surfaces (e.g. Ceramics 10
Gradient composition materials, which are made by laminating and sintering green sheets (09~100% metal) and changing the composition in the thickness direction of the material, have recently been attracting attention.

[Problem to be solved by the invention] Unlike ordinary bulk metal, the sintered layer on the high metal content side often contains minute bores, which impairs strength and reduces heat transfer. .

[Means to solve the problem]

The present invention solves these problems and provides a method for manufacturing a composite material that has excellent physical strength and can be used under severe conditions with a large temperature difference between the front and back surfaces.

The present invention has been made by focusing on the electroplating method. That is, the electroplating method is different from the sintering method in that it is possible to create a dense metal layer. Furthermore, by adding ceramic particles to the plating solution, a composite plating layer in which metal and ceramics are densely composited can be produced. Although a metal layer or a metal-ceramic composite layer made by such an electroplating method has excellent strength and toughness, it is not easy to make a composite layer with a high ceramic content exceeding 40%. As a result, the composite material produced by electroplating did not have sufficient thermal insulation properties.

Therefore, the present inventors succeeded in obtaining a composite material free from the above-mentioned drawbacks by combining the sintering method with the electroplating method.

That is, 11 the present invention is a method for manufacturing a composite material, which is characterized in that a metal layer or a metal-ceramic composite layer is formed by electroplating a composite sintered body obtained by firing a mixture of ceramic powder and metal powder. It is about the method.

The type of ceramic powder and metal powder does not matter; for example, iron powder, nickel powder, cobalt powder, stainless steel powder, high speed steel powder, tungsten carbide powder, silicon carbide powder,
Aluminum powder, zirconium oxide powder, silica powder, silicon nitride powder, titanium nitride powder, titanium boride powder, etc. can be used.

Both the ceramic powder and the metal powder may be a mixture of multiple types. The particle size is 0, which is used in the production of sintered bodies.
, 01-100! About JTn is sufficient. The mixing ratio may be such that the composite sintered body obtained by firing can be electroplated, and if the volume ratio of the metal powder is about 30% or more, good electroplating can be performed.

When used in an environment where there is a large temperature difference between the front and back surfaces, a laminate in which a plurality of green sheets with different metal-ceramic compositions are laminated such that the composition changes in one direction is preferable. The composition is preferably varied in a volume ratio of about 70% metal O, therefore, about 100% to 30% cera fruit. The changes in composition need not be equally spaced. Further, the thickness of each layer is suitably about 0.1 to Inm, although it depends on the purpose of use. This layer thickness may be different for each layer.

The number of laminated layers may be 2 or more, but usually about 3 to 10.

The molded body to be sintered may contain an organic binder, a plasticizer, etc., regardless of whether it is a green sheet or not.

The molded article may be formed by any known method. When forming a laminate of green sheets, a hot plate pressing method is generally used, but a similar method may be used.

The molded body may be sintered by a known method, such as pressureless sintering, hot pressing, HIP, or the like.

The sintering conditions depend on the raw materials, etc., but may be performed at about 800 to 2000''C in an inert gas or reducing gas atmosphere.

The composite sintered body thus obtained is electroplated. The plating solution contains a metal salt of the metal to be plated, as well as a pH buffer, a softener, etc., if necessary. When the plating layer is a metal-ceramics composite layer, fine powder of the ceramic to be plated is dispersed and contained in the plating solution. The appropriate dispersion concentration of the ceramic fine powder is about 10 to 200 g/1. The ratio of metal to ceramics in the deposited plating layer depends on the ratio of both plating solutions, the concentration of ceramics,
It is also affected by current density, plating solution flow rate, etc. Generally, the higher the ceramic concentration, the lower the current density, and the faster the flow rate of the plating solution, the higher the metal ratio.

Conditions such as pH 1 temperature of the plating solution and plating time are preferably determined by conducting tests in advance.

The layer formed by electroplating has a metal to ceramic ratio of about 100 to 50% by volume, preferably 10% by volume.
The content of ceramics is about 0 to 60%, therefore about 0 to 50%, preferably about 0 to 40%. N thickness is usually 0.1 to 1
It is about 0 lungs.

In the case of a compositionally graded composite material, electroplating is applied to the metal-rich layer side of the compositionally graded composite sintered body. The formed plating layer may be a single layer or a composite layer. In the case of a composite layer, the ceramic concentration may change continuously or may change stepwise. Metal of plating layer -
The seven-mix ratio is the concentration of metal salts and ceramics in the plating solution,
Electroplating may be performed in accordance with predetermined conditions by testing the relationship between the electric density and the equal ratio of the flow rate of the plating solution.

The metal-ceramic composition of the plated layer is such that the compositional change continues in one direction from the graded composition composite sintered body.

[Effect]

The metal-ceramic composition of the plating layer formed on the metal-ceramic composite by electroplating is determined by the metal salt concentration of the plating solution, the dispersion concentration of the ceramic particles, the mixing ratio of both,
It varies depending on current density, plating solution flow rate, etc. By controlling these, a metal-ceramic layer having a predetermined composition ratio is formed.

〔Example〕

Example 1 A slurry was prepared by adding 29 parts by weight of Ni powder and 28 parts by weight as a binder to 43 parts by weight of ZrO2 powder. This slurry was formed into a thin layer by the doctor blade method, and after drying, it was fired by heating at 1350''C for 2 hours in an argon gas atmosphere containing 10% hydrogen gas. The ratio is 50%, and the thickness is 0.
．． It was 7 mm.

After the surface of this composite sintered body was degreased and pickled, it was immersed in a Ni plating solution containing ZrO□, and electroplated using the sintered body as a cathode and the Ni plate as an anode. A circulation cell type plating device was used to circulate the plating solution. The plating solution contains 500g of nickel sulfamate/R1 particle size l~
2 Ready-to-read Zr0z powder 20-100g/E and boric acid 30
A solution of pl+3.5 containing g/1 was used. The plating conditions were as follows: liquid temperature: 50'' C, current density: 1 to 5 A/dm2. As a result of setting the current application time according to the current density, a plating layer with a thickness of 304 mm was formed on the sintered body.

The ZrO2 content of this plated layer was determined by fluorescent X-ray method. Obtained ZrO□ content and ZrozeA of plating solution
Figure 1 shows the relationship with degree. In the figure, the circle mark indicates the current density I
The squares indicate the case of 3 A/dm'', and the triangles indicate the case of 5 A/dm2.

Example 2 Thickness: 30 mm, 25% ZrO□-7 obtained in Example 1
A 5% Ni composite plating layer was obtained, and Ni plating was applied on the composite plating layer using a circulation cell type plating device.

The plating solution was a pH 3.5 solution containing nickel sulfamate 500 g/l and boric acid 30 g/f, and current was applied for about 40 minutes at a solution temperature of 50°C and a current density of 3 A/d-.

As a result, a pure Ni plating layer with a thickness of 30 μm was formed on the composite plating layer (50% Zr0z-50% Ni)/(
A composite material consisting of three layers of 25% Zr0z-75% Ni)/100% Ni was obtained. FIG. 2 shows the results obtained by fluorescent X-ray analysis of each layer. Note that the interface between each plating layer was confirmed using a cross-sectional SEM photograph, and it was found to be sound.

Example 3 By changing the mixing ratio of ZrO□ powder and Ni powder, 100% Z
rO□ slurry, 80% ZrO, -20% Ni slurry, 60% ZrO2 -40% Ni slurry and 40% Zr
An O2-60% Ni slurry was prepared. These green sheets were sequentially laminated in the same manner as in Example 1, and the laminated product was fired to form a layer with a thickness of about 0.2 mm+ for each layer.
00% to 40% ZrO2 graded sintered body was obtained. This sintered body contains 40% ZrO.

20% ZrO□-80% N on the layer side in the same manner as in Example 1.
An i-composite plating layer was formed, and a pure Ni plating layer was formed thereon in the same manner as in Example 2. The thickness of both layers was approximately 0.2 mm. As a result, the thickness of 6 layers is 1.
A gradient composition material of 2 mm of 100% Ni to 100% Zr0z was obtained. When the interfaces between each layer of this material were confirmed using a cross-sectional SEM photograph, all of them were found to be sound.

〔Effect of the invention〕

According to the dispersion plating method, the Ni-ZrO□ combination ratio can be easily adjusted, and the plating layer is made of Ni-ZrO□.
It is also possible to form it on an rO2 composite sintered body.

Therefore, by combining a sintered body whose composition is continuously changed and dispersion plating, it is possible to produce a functionally gradient material whose composition is arbitrarily controlled from 0 to 100%.

In the method of the present invention, the heat resistance of the ceramic-rich sintered body and the strength and toughness of the metal-rich composite layer made by electroplating are combined, resulting in excellent heat resistance and, at the same time, strength and toughness. A composite material with excellent toughness was obtained. Conventionally, electroless plating has been used to reinforce or impart conductivity to ceramic materials, but in the case of the present invention, at least the surface to be plated is a composite sintered layer containing metal, so electroless plating is not required. Electroplating can be applied without the need for The advantage of electroplating is that the film formation speed is fast.

The plating solution should be easy to manage.

Furthermore, the composition of the film can be easily controlled.

[Brief explanation of drawings]

Figure 1 is a diagram showing the relationship between the ZrO□ concentration of the plating solution obtained in the example and the Zr0t content of the plating layer, and Figure 2 shows the relationship between each layer of the three-layer composite material obtained in the example. It is a figure which shows the chart which measured Ni and Zr content by the fluorescent X-ray method.

Claims (3)

[Claims] (1) A method for producing a composite material, which comprises electroplating a composite sintered body obtained by firing a mixture of ceramic powder and metal powder to form a metal layer or a metal-ceramics composite layer. (2) Electroplating is applied to the metal-rich layer side of a graded composition composite sintered body obtained by laminating and firing multiple green sheets with different metal-ceramic composition ratios so that the composition changes in one direction. A method for producing a graded composition composite material, comprising forming a metal layer or a metal-ceramics composite layer by (3) Claim (2) wherein the ceramic concentration of the metal-ceramics composite layer decreases continuously or stepwise from the sintered body side.
) The manufacturing method of the composite material described in