Patent EP0276334A1 successfully refreshed from Google Patents.
EP0276334A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Silicon nitride-silicon carbide composite material and process for production thereof
Assignee: Mitsubishi Gas Chemical Co Inc
•
Filing: 1987-01-22
•
Granted: —
•
Expires: 2007-01-22
Abstract
Abstract The present sintered composite material is substantially formed of silicon nitride predominantly in β-phase and about 5 to 35% by weight of silicon carbide predominantly in β-phase, which is characterized by the microstructure such that the silicon nitride is in the form of fine grains comprising:-elongated grains 0.2 to 1.0 um in length of minor axis and 1 to 10 µm in length of major axis, and equiaxed grains 1 um or below in average size: and the silicon carbide is in the form of equiaxed grains 1 um or below in average size, said silicon carbide grains being uniformly dispersed. Having a three-point flexural strength of at least 95 kc/mm 2 and a fracture toughness (K lc ) of at least 54 MN/m 3/2 , the present sintered material is excellent in toughness and strength. The process for producing such a material is disclosed in detail.
Inventors
- 👤 Kansei Izaki
- 👤 Takamasa Kawakami
- 👤 Kouichi Hakkei
- 👤 Kazuhiro Ando
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 14:51
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C04B35/589; C01; C01B; C01B21/00; C01B21/06; C01B21/068; C01B32/00; C01B32/90; C01B32/914; C01B32/956; C01B32/963; C01B32/977; C04B35/593; C04B35/5935; C01P; C01P2002/00; C01P2002/02; C01P2004/00; C01P2004/01; C01P2004/03; C01P2004/30; C01P2004/32; C01P2004/60; C01P2004/61; C01P2004/62; C01P2006/00; C01P2006/10; C01P2006/80; C01P2006/90
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
101 words
A sintered silicon nitride-silicon carbide composite material comprising substantially silicon nitride predominantly in 8-phase and about 5 to 35% by weight of silicon carbide predominantly in β-phase, which is characterized by such microstructure that the silicon nitride is in the form of fine grains comprising elongated grains, 0.2 to 1.0 µm in length of minor axis and 1 to 10 µm in length of major axis, and equiaxed grains, 1 µm or below in average size, and the silicon carbide is in the form of equiaxed grains. 1 µm or below in average size, said silicon carbide grains being uniformly dispersed.
Claim 2
Dependent Claim
101 words
A sintered silicon nitride-silicon carbide composite material comprising substantially silicon nitride predominantly in 8-phase and about 5 to 35% by weight of silicon carbide predominantly in β-phase, which is characterized by such microstructure that the silicon nitride is in the form of fine grains comprising elongated grains, 0.2 to 1.0 µm in length of minor axis and 1 to 10 µm in length of major axis, and equiaxed grains, 1 µm or below in average size, and the silicon carbide is in the form of equiaxed grains. 1 µm or below in average size, said silicon carbide grains being uniformly dispersed.
Claim 3
Dependent Claim
45 words
A sintered silicon nitride-silicon carbide composite material according to Claim 1, wherein the sintered composite material has a three-point flexural strength of at least 95 kgimm 2 at a room temperature and a fracture toughness (K lC ) of at least 5.4 MN/m 3/2 .
Claim 4
Dependent Claim
190 words
A process for producing the sintered silicon nitride-silicon carbide composite material of Claim 1, which comprises heat-treating an amorphous composite powder having a composition represented by the general formula SiC a N b H e , wherein 0.1 < a < 2.0, 0.1 < b < 1.5, and 0 < c < 4.0, at a temperature of 1,000°C or higher but below 1,300°C under an atmosphere of one non-oxidizing gas selected from nitrogen, argon, helium and hydrogen, or at a temperature from 1,300° to 1,400°C under a stream of the linear velocity of at least 0.05 cm / sec. of one non-oxidizing gas selected from nitrogen, argon and helium, thereby to obtain an amorphous, spherical composite powder of the composition represented by the general formula SiC x N y O z , wherein 0 < x < 1.5. 0 < y < 2.0 and 0 < z < 0.2 and having an average particle size of 1 µm or below, mixing the resulting amorphous composite powder with 1 to 15% by weight of a sintering aid, and sintering the resulting mixture under a non-oxidizing gas atmosphere while applying a pressure.
Claim 5
Dependent Claim
40 words
A process according to Claim 3, wherein the sintering aid is at least one substance selected from magnesia (MgO), alumina (Al 2 O 3 ), yttria (Y 2 O 3 ), ceria (CeO,) and lanthana (La 2 O 3 ).
Claim 6
Dependent Claim
63 words
A process according to Claim 3, wherein said amorphous spherical composite powder of the composition represented by the general formula SiC x N y O z , wherein 0 < x < 1.5, 0 < y < 2.0 and 0 < z < 0.2, has a carbon content of 1.5 to 10.5% by weight, an oxygen content of 5% by weight or below.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.