Plastic and nonmetallic article shaping or treating: processes – Including step of generating heat by friction
Patent
1994-04-26
1995-09-26
Jones, Deborah
Plastic and nonmetallic article shaping or treating: processes
Including step of generating heat by friction
264 66, 501 97, 501 98, C04B 3510, C04B 3558
Patent
active
054532329
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
An improved sialon composition with superior mechanical and thermal properties is disclosed.
BACKGROUND ART
U.S. Pat. No. 5,030,600 of George T. Hida et al. discloses a composite material containing at least 70 weight percent of single-phase beta sialon and at least 20 weight percent of alpha-alumina. Although the composite material of this patent has excellent mechanical and thermal properties, its properties are not good enough for use in severe environments requiring a particular combination of excellent thermal and excellent mechanical properties.
It is an object of this invention to provide a sialon material which a hardness at least 19 GigaPascals, a strength of at 1,000 megaPascals (at room temperature), a fracture toughness of at least 6 megaPascals, and a strength decay at 1,350 degrees Celsius of less than 25 percent.
DISCLOSURE OF INVENTION
In accordance with this invention, there is disclosed a sialon composition which consists essentially of at least 70 weight percent of beta-prime-sialon, and at least 27 weight percent of a solid solution containing silicon nitride, alumina, and aluminum nitride.
BRIEF DESCRIPTION OF THE DRAWING
The present invention will be more fully understood by reference to the following detailed description thereof, when read in conjunction with the attached drawings, wherein like reference numerals refer to like elements and wherein:
FIG. 1 is a flow sheet of a preferred embodiment of the process of this invention.
BEST MODE FOR CARRYING OUT THE INVENTION
The composite material produced by the process of this invention preferably consists essentially of two phases, a beta-prime sialon compound and a sialon solid solution.
The beta-prime sialon compound is primarily synthesized. The term "primarily synthesized" is described in U.S. Pat. No. 5,030,600, the entire disclosure of which is hereby incorporated by reference into this specification. Thus the beta-prime-sialon compound preferably has no replaceable cations. In the majority of crystal lattices of this sialon compound, only silicon, aluminum, oxygen, and nitrogen atoms preferably appear.
In one preferred embodiment, the beta-prime-sialon compound is of the formula Si.sub.6-z Al.sub.z O.sub.z N.sub.8-z (wherein z is from about 2.5 to about 3.5).
The material produced by the process of this invention comprises at least about 70 weight percent of said beta-prime-sialon compound, wherein z is from about 2.5 to about 3.5. It is preferred that the material comprise at least about 72 weight percent of said beta-prime-sialon compound. It is most preferred that the material contain at least 73 weight percent of the beta-sialon material.
Without wishing to be bound to any particular theory, applicants believe that the presence of the beta-sialon compound in their material tends to produce a superior material because such compound does not contain replaceable cations, such as the yttrium, zirconium and magnesium cations which are commonly present in prior art beta-sialon materials (which are solid solutions).
The material of this invention preferably contains at least two phases. In this embodiment, in addition to containing at least 70 weight percent of said beta-prime-sialon compound, such material also contains at least 27 weight percent of a specified sialon solid solution.
The sialon solid solution which is present in applicant's material contains alpha-silicon nitride, aluminum nitride, and alpha-alumina.
In general, such sialon solid solution contains from about 2 to about 50 weight percent, by weight of solid solution, of alpha-silicon nitride and from about 0.5 to about 14 percent of aluminum nitride, by weight of said solid solution.
The sialon solid solution also contains from about 97.5 to about 36 weight percent of alpha alumina, by weight of said solid solution.
The material of this invention may be sintered without pressure and without the use of sintering aids. It is preferred, however, to mix such material with a binder prior to forming it. Thus, one may use the binders described
REFERENCES:
patent: 3375073 (1968-03-01), McMullen
patent: 3837871 (1974-09-01), Weaver
patent: 4243621 (1981-01-01), Mori et al.
patent: 4360506 (1982-11-01), Paris et al.
patent: 4365022 (1982-12-01), Tabata et al.
patent: 4499193 (1985-02-01), Phelps et al.
patent: 4812298 (1989-03-01), Kohtoku et al.
patent: 4957885 (1990-09-01), Hida
patent: 4990295 (1991-02-01), Hida
patent: 5006290 (1991-04-01), Hida
patent: 5030600 (1991-07-01), Hida
patent: 5192720 (1993-03-01), Hida et al.
patent: 5221647 (1993-06-01), Hida et al.
Delcea Cezar C.
Hida George T.
Hida Rodica S.
Benchmark Structural Ceramic Corporation
Greenwald Howard J.
Jones Deborah
LandOfFree
Sialon composition does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Sialon composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sialon composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1550752