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.beta.'-Sialon sintered body and a method for manufacturing the same
| Details |
Inventors: Mori, Masaaki; Ogawa, Tamotu; Takai, Norihira;
Assignee: Toshiba Ceramics Co., Ltd. (Tokyo, JP)
Primary Examiner: Parrish; John A.
Assistant Examiner:
Attorney, Agent or Firm: Bacon & Thomas
This invention provides a method for manufacturing said sintered body, comprising preparing a starting material by adding 10 to 1,000 wt. parts of metal silicon powder to 100 wt. parts of mixed powder composed of 20 to 80 wt. % silica powder and 80 to 20 wt. % aluminium powder and mixing said powders thoroughly, further adding, if required, a refractory fine powder of alumina, silicon nitride, aluminium nitride, .beta.'-sialon, aluminium nitride polytype sialon, or silicon carbide, molding the resultant mixture into a green compact, and then sintering said green compact in a nitrogeneous nonoxidative gas atmosphere at a temperature of 1,200.degree. to 1,550.degree. C. This invention further provides a compact sintered body which will be prepared by the above mentioned method. |
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Now this invention will be described in detail.
First, a starting material powder is prepared by adding 10 to 1,000 wt.
parts of metal silicon powder to 100 wt.
parts of mixed powder composed of 20 to 80 wt.
% silica powder and 80 to 20 wt.
% aluminium powder and mixing them thoroughly.
Then, this starting material powder is molded into a desired shape by various molding methods, such as die press, rubber press, slip casting, and extrusion, and thereafter the resultant green compact is sintered in a nitrogenous nonoxidative gas atmosphere at a temperature of 1,200.
degree.
to 1,550.
degree.
C.
, thereby manufacturing a reaction-sintered body mainly composed of .
beta.
'-sialon.
The silica powder available for the invention may be selected from a group including crystal powder, silica sand powder, quartz glass powder, volatile silica, chemicalprecipitation silica, and gas phase method silica.
Among these the pulverized volatile silica is best suited for use as the silica powder because it is high in reactivity, producing a lot of .
beta.
'-sialon and reducing the sintering time.
It is preferable to employ silica powder having a particle size of less than 200 meshes.
Examples of aluminium powder applicable for the invention may be atomized powder (spray powder) and flakelike powder of aluminium, having a particle size of preferably less than 50 meshes.
The metal silicon powder applicable for the invention is preferably of particle size finer than 200 meshes, and may be crystalline or amorphous.
The reason why the ratio of silica powder to aluminium powder (SiO.
sub.
2 powder/Al powder) is limited to the aforesaid range is that if the ratio SiO.
sub.
2 power/Al power is reduced below 20/80 (by weight), some Al will remain unreacted or the yield of AlN and/or Y-phase sialon will be increased, which will naturally lead to reduction in the amount of .
beta.
'-sialon produced, prohibiting strong reaction-sintered body from being obtained.
Meanwhile, if the ratio SiO
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Manufacturing Materials 
