JPS6256501A - Composite sintered body of ceramics and powder metal - Google Patents

Abstract

PURPOSE:To provide a titled composite sintered body which can be selectively used for both applications of electricity conduction and insulation and in which ceramics and sintered metallic body layer are thoroughly united by forming the sintered metallic body to the outside circumference of the ceramics. CONSTITUTION:A metal alone or a mixture prepd. by uniformly mixing the metallic powder and binder at a prescribed compsn. is packed into a metallic mold recessed with a prescribed shape and 5-45kg/mm<2> pressure is exerted thereto to form a compression molding. An insertion hole for the ceramics 2 is recessed to the compression molding simultaneously with or after compression molding and the ceramics 2 is inserted into the insertion hole. The compression molding is then put into a sintering furnace and is subjected to preliminary heating in a reducing or inert gaseous atmosphere or vacuum then to calcination at the sintering temp. meeting the sintered metallic body layer 1. The compression molding shrinks to the higher density during the calcination and compacts the ceramics 2 with the high pressure, thus penetrating the molten metal into the ceramics 2 at the boundary thereof and forming an intermediate layer 2 thereof. The composite sintered body thoroughly united with the ceramics and the powder metal is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a composite sintered body made of ceramics and powder 4, and more specifically, a sintered metal body layer (1) of metal powder on the outer periphery of ceramics (2). This invention relates to a composite sintered body of ceramics and powdered metal characterized by forming.

Ceramics have many excellent properties such as electrical insulation, high hardness, corrosion resistance, chemical resistance, and low expansion coefficient, and have been used for a variety of purposes including insulators and plugs since ancient times. However, although its properties have been improved in recent years, it still has many negative aspects, such as being extremely brittle against shock loads, tensile strength, heat shock, etc., and having no machinability. .

On the other hand, sintered metal bodies are made by uniformly blending a single metal powder or a metal powder and a binder, compressing and molding it into a predetermined shape, and then sintering it.
Although it has excellent mechanical properties such as heat shock and toughness and machinability, it is generally prone to rust, has a large coefficient of thermal expansion, and is a good conductor, which is the opposite of ceramics.

The present invention has been made by focusing on the advantages and disadvantages of such conventional ceramics and sintered metal bodies, and its purpose is to complement each other's disadvantages and bring out only their advantages. To provide a composite sintered body of ceramics and powder metal.

Hereinafter, the present invention will be described in detail according to illustrated embodiments.

Examples of metal powder materials include iron, copper, etc., and hard alloy powders (for example, tungsten carbide, titanium carbide, zirconium carbide, tantalum carbide, etc., and cobalt, nickel, etc. are used as binders), etc. All metals that can be powdered can be used. Ceramics (
2) is ^120. It is made by adding a small amount of cobalt as a binder and sintering it. First, a metal powder alone or a metal powder and a binder are uniformly mixed in a predetermined composition. In the case of cemented carbide, as the amount of binder increases, the hardness of the sintered metal body/l (1) decreases, but the toughness improves. ! First, this mixture was filled into a mold with a predetermined shape, and 44 to 45 k.

A pressure of /+us' is applied to create a compression molded product.

At this time, an insertion hole for the ceramic (2) is provided in the compression molded product at the same time as or after the compression molding, and the ceramic (2) is fired after being inserted into the insertion hole. The fitting of the seven laminates (2) and the insertion hole is as follows:
Since the compression molded body contracts during sintering, a loose fit is sufficient. For compression molded products with large shapes, filling and compression are performed in several batches.

The number of ceramics (2) to be inserted does not have to be one, and may be multiple depending on the design.In this way, first, compression molding is performed with the ceramics (2) inserted in one or multiple places. Next, this compression-molded body is placed in a sintering furnace, preheated in a reducing or inert gas atmosphere or in a vacuum, and then combined into a sintered metal body 1 (1). Washeda sintering temperature (for example, 1,400℃ for cemented carbide)
Fired at high temperatures (inside and outside).

During firing, the compression molded body contracts and becomes 1llllffi, and the ceramic (2) is tightened under high pressure, and at the boundary, the metal molten in the ceramic (2) penetrates and forms an intermediate layer (3). Complete integration is achieved. The sintered metal body/11(1) may be a dense body similar to a cast material, or it may be porous.If it is porous, the sintered metal body/I(1) itself absorbs thermal expansion. Therefore, it can follow the low coefficient of thermal expansion of ceramics (2), making it ideal for locations where the coefficient of thermal expansion is a problem. Furthermore, the heat dissipation effect of the sintered metal body N(1) cannot be overlooked. Composite sintered body taken out from the sintering furnace (＾
), the sintered metal body layer (1) is subjected to various machining processes, including, for example, screw machining, and is used for various purposes.

In the above case, the insertion hole is first formed and the ceramic (2) is then inserted and sintered. However, this is not limited to this, of course.
2) may be provided in advance, and then the metal powder may be filled and compressed into the mold.

In addition, when the insertion hole is a blind hole, when the ceramic (2) and the compression molded body are fired, the edge of the insertion hole and the ceramic (2) are first welded to each other as shown in Fig. 5, and the insertion hole is closed. A gas pocket (4) occurs at the bottom of the hole, and gas accumulates during sintering (
4) expands and causes the sintered metal body layer (1) to swell, so as shown in Figures 2 to 4, the ceramic (
It is desirable to provide gas vent holes (5) in the second layer (or in the sintered metal body layer (1)).

However, if the sintered metal body layer (1) is of open cell type, the gas vent holes (5) are not required.

As described above, the present invention involves forming a sintered metal layer on the outer periphery of the ceramic, so that the sintered metal layer protects the ceramic. ! ! Even if the ceramic is subjected to tensile force, impact load, heat shock, etc., the sintered 4R metal layer absorbs the debris and prevents the ceramic from breaking.On the other hand, when a compressive load is applied, A boat can be made in which the ceramic resists the bar and prevents the sintered metal layer from buckling or collapsing.

In addition, since the sintered metal body layer is formed on the outer periphery of ceramics, the sintered metal body M+ is subjected to mechanical processing, even though the main part is made of ceramics.
It can be used in the same way as metal materials, and can be newly applied to applications where ceramics could not be used conventionally. In addition, since the sintered metal body 7' is a good conductor of heat and electricity, it can effectively dissipate the heat generated in the ceramic part and prevent the ceramic from overheating. By using layers and ceramic parts for insulation, it can be used for both electrical conduction and insulation purposes. In addition, since the sintered metal layer is formed around the outer periphery of the ceramic, the sintered metal layer contracts during sintering, and the ceramic is strongly tightened to the sintered-fk metal layer, causing the boundary between the two to shrink. The advantage is that the gap disappears and then the molten metal penetrates into the ceramic at the boundary between the ceramic and the sintered metal body layer of metal powder, forming an intermediate layer and completely integrating the two. There is.

[Brief explanation of drawings]

Fig. 1... A vertical cross-sectional view of an embodiment of the present invention, Pt42 Fig.... A longitudinal cross-sectional view when the insertion hole of the sintered metal body layer of the present invention is a blind hole, Fig. 3... A plan view of FIG. 2. FIG. 4: A plan view of another embodiment in which the insertion hole of the sintered metal layer of the present invention is a blind hole. FIG. 5: A plan view of the sintered metal layer of the present invention. A vertical cross-sectional view when the push-in hole is a blind hole and the sintered metal body/layer expands. (1)...Sintered metal body M (2)...Ceramics (
3)...Medium 11f1 layer (4)...Gas reservoir (5)...Slot hole (^)...Composite sintered body. Inventor Chiaki Takami Figure 1△ Figure 5 ゛Figure 2

Claims (4)

[Claims] (1) A composite sintered body of ceramics and powder metal, characterized by forming a sintered metal layer on the outer periphery of ceramics. (2) A composite sintered body of ceramics and powder metal according to claim 1, characterized in that the sintered metal body layer is formed porous. (3) A composite sintered body of ceramics and powder metal according to claim 2, characterized in that the cells in the sintered metal layer are of an open cell type. (4) A composite sintered body of ceramics and powder metal according to claim 2, wherein the cells in the sintered metal layer are of a closed cell type.