Plastic and nonmetallic article shaping or treating: processes – Outside of mold sintering or vitrifying of shaped inorganic... – Including plural heating steps
Patent
1995-06-05
1997-09-09
Derrington, James
Plastic and nonmetallic article shaping or treating: processes
Outside of mold sintering or vitrifying of shaped inorganic...
Including plural heating steps
264 85, 264570, 264325, 264683, C04B 35584
Patent
active
056652917
ABSTRACT:
The specification describes a method for producing high density sintered silicon nitride (Si.sub.3 N.sub.4) having a relative density of at least 98%. In a first step, silicon nitride powder is compacted into a desired shape. It is then pre-sintered in a second step, generally, under normal pressure to obtain a presintered body having a relative density of at least 92%. In a third step, the presintered body is subjected to a hot isostatic pressing (HIP) in an inert gas atmosphere of 1500.degree.-2100.degree. C. and of nitrogen gas partial pressure of at least 500 atm. Since the presintering does not require any capsule, it is possible to produce high density sintered Si.sub.3 N.sub.4 of complex configurations. As a sintering aid, Y.sub.2 O.sub.3 --Al.sub.2 O.sub.3 --MgO system sintering aid is particularly effective. To improve the strength of sintered Si.sub.3 N.sub.4, it is effective to add a heat treatment step after the HIP and maintain the temperature of the sintered Si.sub.3 N.sub.4 above 500.degree. C. for a while. Between the second and third steps, the temperature of the presintered body is preferably maintained above 500.degree. C. These temperature controls are effective not only to improve the strength of sintered Si.sub.3 N.sub.4 but also to save the thermal energy and to shorten the production cycle.
REFERENCES:
patent: 4112143 (1978-09-01), Adlerborn
patent: 4196178 (1980-04-01), Iwai et al.
patent: 4264548 (1981-04-01), Ezis
patent: 4296065 (1981-10-01), Ishii et al.
patent: 5445776 (1995-08-01), Honma et al.
Abstract of German Patent 2621523.
Kobe Steel, Ltd., No. 313011, Hot and Cold Isostatic Pressing Equipment, pp. 1-10.
Kobe Steel, Ltd., No. 428090, Hot Isostatic Press, pp.1-6.
Fujikawa Takao
Honma Katuhiko
Moritoki Masato
Okada Hiroshi
Tatsuno Tsuneo
Derrington James
Kabushiki Kaisha Kobe Seiko Sho
LandOfFree
Method for producing high density sintered silicon nitride(Si.su does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for producing high density sintered silicon nitride(Si.su, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for producing high density sintered silicon nitride(Si.su will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-67225