Plastic and nonmetallic article shaping or treating: processes – Including step of generating heat by friction
Patent
1991-02-12
1992-08-18
Lechert, Jr., Stephen J.
Plastic and nonmetallic article shaping or treating: processes
Including step of generating heat by friction
264 56, 264 65, 264125, 419 10, 419 11, 419 12, 419 29, 419 42, 419 45, 419 48, 419 53, 419 54, 419 55, 501 87, 501 88, 501 96, F27B 904
Patent
active
051397200
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
The present invention concerns a novel method of manufacturing a sintered ceramic material and, more in particular, it relates to a method of manufacturing a sintered ceramic material capable of modifying various characteristics of a sintered ceramic material over a wide range even for a raw material of an identical composition and excellent in the controllability and the homogenity of a fine texture by sufficiently controlling the fine texture in a sintering step for a short period of time depending on the purpose.
The present invention also relates to a method of manufacturing a novel sintered composite ceramic material and, more in particular, it relates to a method of manufacturing a sintered composite ceramic material of extremely good quality in which the phase composition of a composite ceramic, the structure and the distribution of various kinds of constituent phases and the crystal grain size are controlled sufficiently, by conveniently proceeding a thermit reaction under a pressurized state, and utilizing a great amount of heat of reaction obtained in a short period of time.
BACKGROUND OF THE INVENTION
Various characteristics of a sintered ceramic material depends strongly on a fine texture thereof. Accordingly, ceramic sintering methods have been developed, selected and improved as various kinds of heat processing techniques so as to find a method of controlling the fine texture required for attaining aimed characteristics of a sintered ceramic material regarding various factors such as the kind of the raw ceramic powder, characteristics of the material powder, absence or presence of a sintering binder or material of ceramic in the pre-stage of sintering, for example, powder charging ratio of a molding product, crystal structure and physical properties of powder. One of the greatest subjects on the method of manufacturing such a sintered ceramic material is to establish a sintering method having controllability of a fine texture over a wide range capable of attaining aimed characteristics of the sintered ceramic material while ensuring high densification.
Means for dissolving the subject are generally classified into (i) development of a raw sintering powder having high quality and versatile nature, (ii) development of a powder processing technique including, for example, development of various kind of powder molding techniques while taking the performance and the productivity of the sintered material also into consideration, (iii) search for the fine texture controlling agent such as various kinds of binders and (iv) development for sintering and processing technique therefor including, for example, development of a heating method or heat treatment process, for which various research and development have been conducted. However, in an actual sintering process, since the existent powder processing technique and the heat sintering process technology are in an extremely complicate relationship the fine texture greatly varies locally or entirely or often lacks in the reproducibility, also in the sintering of a ceramic powder of constant powder characteristics and molding conditions, due to slight fluctuations of parameters in the sintering process (temperature, heating rate, etc.) or or slight changes such as of inevitable impurities in the powder and mold density.
On the other hand, for the manufacture of a sintered composite ceramic material, a method of sintering and densification by heating for a long period of time has been adopted usually. One of most prominent subjects in the conventional manufacturing method is that it is not possible to obtain a polyphase sintered ceramic material which is dense and comprises fine crystal grains and in which various kind of ceramic phase constitutions in the sintering material is sufficiently controlled in accordance with the purpose. For promoting the densification, there is a press-sintering method, for example, a hot press (HP) or hot isostatic press (HIP) method and, further a high pressure sintering method of apply
REFERENCES:
patent: 4062985 (1977-12-01), Andersen
patent: 4150975 (1979-04-01), Miyake et al.
patent: 4689077 (1987-08-01), Chevigne et al.
Shishiba Hideki
Takeda Shuichi
Kabushiki Kaisha Komatsu Seisakusho
Lechert Jr. Stephen J.
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