Specialized metallurgical processes – compositions for use therei – Compositions – Consolidated metal powder compositions
Reexamination Certificate
2002-03-25
2004-06-08
Jenkins, Daniel (Department: 1742)
Specialized metallurgical processes, compositions for use therei
Compositions
Consolidated metal powder compositions
C419S010000, C419S035000, C419S027000, C075S249000
Reexamination Certificate
active
06746507
ABSTRACT:
This application claims the benefit of Japanese Application 2001-096250, filed Mar. 29, 2001, and Japanese Application 2002-076785, filed Mar. 19, 2002, the entireties of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to a production method of a composite material composed of a dispersing agent and a matrix and to a composite material produced by the production method.
A composite material is a composition aggregate in which plural raw materials are macroscopically mixed to provide characteristics, which a raw material alone could not realize, by complementarily utilizing mechanical properties that each raw material possesses. Basically, the method of producing a composite material is a technical method by which a material is combined with other material, and there are various combinations depending on matrixes and dispersing agents, intended purposes, or cost and the like.
Among them, metal matrix composites and intermetallic matrix composites are composite materials that are made by using a metal like Al, Ti, Ni, Nb and others, or an intermetallic compound like TiAl, Ti
3
Al, Al
3
Ti, NiAl, Ni
3
Al, Ni
2
Al
3
, Al
3
Ni, Nb
3
Al, Nb
2
Al, Al
3
Nb and others as a matrix and using an inorganic material like ceramics and others as a dispersing agent. Accordingly, metal matrix composites and intermetallic matrix composites are materials intended for use in the aerospace field and the automobile industry by making the best use of their properties of light weight and high strength, and especially metal matrix composites, in recent years, are contemplated to utilize in many fields, including electronics represented by electronic devices, by making the best use of the properties of low thermal expansion and high thermal conduction.
Production methods of intermetallic compound-based composite material include a method in which intermetallic compound powder is produced by mechanical alloying (MA) and the like in advance, and then the powder is hot-pressed (HP) or hot isostatic-pressed (HIP) with fibers and/or particles as dispersing agent under the conditions of high temperature and high pressure. And, production methods of metal-based composite material include solid state fabrication techniques like a method in which materials are hot-pressed (HP) or hot isostatic-pressed (HIP) under the conditions of high temperature and high pressure, and liquid phase methods like a pressurized impregnation method in which a molten metal is impregnated and a squeeze casting method in which high pressure is needed.
SUMMARY OF THE INVENTION
As problems in the conventional production methods for producing metal matrix composites and intermetallic matrix composites, in order to produce fine composite materials, not only do fine matrixes need to be formed by loading high temperature and high pressure in production methods of hot-pressing, hot isostatic-pressing and the like but the performance and scale of production equipment are restricted, consequently there are such problems that it is extremely difficult to produce large-sized or complex-shaped composite materials, in addition, it is impossible to perform a near net shaping in consideration of the shape of an end product, and mechanical processing treatment is needed in a later process.
Further, as a pretreatment process in the production of an intermetallic compound-based composite material, a process is needed to synthesize intermetallic compound powder by mechanical alloying and the like in advance, accordingly there is such a problem that the production process has multiple stages and is complicated. As a result, as described above, the conventional method of producing metal matrix composites and intermetallic matrix composites is an extremely high cost production method because not only does the method need a multistage process but it is carried out under high temperature and high pressure.
In order to solve these problems, Japanese Patent Publication No. 2609376 and Japanese Patent Application Laid-Open No. 9-227969 disclose production methods of composite materials in which methods using a preform composed of a metal oxide and others that can be reduced with Al and the like, the preform is made to react with liquid Al and the like in the surface layer to synthesize aluminide intermetallic compounds and oxides (especially Al
2
O
3
) in-situ synthesis.
However, according to the production methods disclosed in Japanese Patent Publication No. 2609376 and Japanese Patent Application Laid-Open No. 9-227969, because the kinds of dispersing agents to be dispersed in obtained composite materials are limited, intended material designs are limited to some specific combinations and it becomes difficult to change the properties of composite materials. Further, the methods have such a problem that if the ratio of materials to be used is not strictly controlled, metal oxides and others or Al and others may remain. Moreover, since a large quantity of reaction heat is generated in a moment, there may be some cases where reaction control is difficult.
On the other hand, among composite materials, porous composite materials having a lot of pores (hereinafter described as “porous composite materials”) exhibits various kinds of effect due to as well as being light compared to composite materials having fine microstructures (hereinafter described as “fine composite materials”). In addition, in the case that pores are introduced into the matrix, generally, mechanical properties such as strength, Yong's modulus and the like decrease though the material becomes lighter as its porosity increases.
Further, up to now some trials have been performed to make obtained porous composite materials light by making hollow particles compound with a metal of Al or the like, and there has been mainly employed as a production process a pressurized impregnation method in which operations under pressure are required when a metal of Al or the like is impregnated into gaps among hollow particles. According to the pressurized impregnation method, however, there are such problems that crushing, breaking or the like are easily caused in hollow particles when a metal of Al or the like is impregnated. That is, hollow particles are broken due to static pressure of a molten metal in the case that a higher pressure is applied to the molten metal to impregnate it into the gaps, and the molten metal occupies the inner portions of the broken hollow particles. This results in failure to lightening the product. On the other hand, however, the gaps among the hollow particles will not be fulfilled sufficiently with the molten metal, in the case that a pressure for impregnating the molten metal into the gaps is reduced so as not to break the hollow particles. This results in the formation of internal defects, such as cavities. Consequently, there are some cases that expected properties, e.g., light weight are not given to obtained composite materials or that the improvements in the specific strength, specific elasticity, and the like were not achieved.
The present invention has been done in view of these problems associated with conventional arts and aims at providing a production method and composite materials produced by the production method, which production method reduces and simplifies the production processes and at the same time, produces a metal-based composite material, an intermetallic compound-based composite material, and a composite material in a state in which a metal and an intermetallic compound are mixed is used as a matrix, which composite materials are also applicable to large-sized and complex-shaped end products.
That is, according to the present invention, there is provided a production method of a composite material composed of a dispersing agent and a matrix, which comprises: forming a metal-coated layer on the surface of said dispersing agent to prepare a metal-coated dispersing agent, filling said metal-coated dispersing agent in a jig prepared in a fixed shape, and then causing the react
Ishikawa Takahiro
Kida Masahiro
Ochiai Toshimasa
Shinkai Masayuki
Burr & Brown
Jenkins Daniel
NGK Insulators Ltd.
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