Patent US4650498A successfully refreshed from Google Patents.
US4650498A
Expired / Lapsed
US
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Abrasion resistant silicon nitride based articles
Assignee: Verizon Laboratories Inc
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Filing: 1984-12-14
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Granted: 1987-03-17
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Expires: 2004-12-14
Abstract
Abstract Composite articles and cutting tools are prepared by densification to form a body consisting essentially of particles of hard refractory boride uniformly distributed in a silicon nitride matrix consisting essentially of a first phase and a second phase. The first phase consists essentially of crystalline silicon nitride and the second phase is an intergranular refractory phase comprising silicon nitride and a suitable densification aid selected from the group consisting of yttrium oxide, cerium oxide, zirconium oxide, hafnium oxide and the lanthanide rare earth oxides and mixture thereof. The resulting composite article or cutting tool has a fracture toughness equal to or greater than about 4 MN/m 3/2 .
Inventors
- 👤 Sergej-Tomislav Buljan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 13:21
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C04B35/593
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
102 words
A densified composite ceramic article consisting essentially of particles of a hard refractory boride uniformly distributed in a two phase matrix, said two phase matrix consisting essentially of a first phase and a second intergranular phase, said first phase consisting essentially of crystalline silicon nitride, said second intergranular phase consisting essentially of silicon nitride and a densification aid, said densified composite ceramic article having a density greater than 99% of theoretical density, a high abrasion resistance, a high hardness, a fracture toughness equal to or greater than 4 MN/m 3/2 , and a resistance to oxidation at temperatures greater than 1200° C.
Claim 2
Dependent Claim
102 words
A densified composite ceramic article consisting essentially of particles of a hard refractory boride uniformly distributed in a two phase matrix, said two phase matrix consisting essentially of a first phase and a second intergranular phase, said first phase consisting essentially of crystalline silicon nitride, said second intergranular phase consisting essentially of silicon nitride and a densification aid, said densified composite ceramic article having a density greater than 99% of theoretical density, a high abrasion resistance, a high hardness, a fracture toughness equal to or greater than 4 MN/m 3/2 , and a resistance to oxidation at temperatures greater than 1200° C.
Claim 3
Dependent Claim
27 words
A densified composite ceramic article in accordance with claim 1 wherein said hard refractory boride comprises from about 1 to about 60 volume percent of said article.
Claim 4
Dependent Claim
29 words
A densified composite ceramic article in accordance with claim 1 wherein said particles of hard refractory boride comprise from about 15 to about 50 volume percent of said article.
Claim 5
Dependent Claim
32 words
A densified composite ceramic article in accordance with claim 1 wherein said particles of a hard refractory boride are selected from the group consisting of titanium boride, hafnium boride, and mixtures thereof.
Claim 6
Dependent Claim
37 words
A densified composite ceramic article in accordance with claim 1 wherein said densification aid is selected from the group consisting of yttrium oxide, cerium oxide, zirconium oxide, hafnium oxide, the lanthanide rare earth oxides and mixtures thereof.
Claim 7
Dependent Claim
27 words
A densified composite ceramic article in accordance with claim 1 wherein said particles of hard refractory boride are of an average size less than about 20 microns.
Claim 8
Dependent Claim
27 words
A densified composite ceramic article in accordance with claim 1 wherein said densification aid comprises from about 1 to about 25 weight percent of said composite article.
Claim 9
Dependent Claim
20 words
A densified composite ceramic article in accordance with claim 1 wherein said hard refractory boride consists essentially of titanium boride.
Claim 10
Dependent Claim
115 words
A densified composite ceramic cutting tool consisting essentially of particles of a hard refractory boride uniformly distributed in a two phase matrix, said two phase matrix consisting essentially of a first phase and a second intergranular phase, said first phase consisting essentially of crystalline silicon nitride, said second intergranular phase consisting essentially of silicon nitride and a densification aid, said two phase matrix containing less than 3 weight percent aluminum oxide, said densified composite ceramic article having a density greater than 99% of theoretical density, a high abrasion resistance, a high hardness, a fracture toughness equal to or greater than 4 MN/m 3/2 , and a resistance to oxidation at temperatures greater than 1200° C.
Claim 11
Dependent Claim
115 words
A densified composite ceramic cutting tool consisting essentially of particles of a hard refractory boride uniformly distributed in a two phase matrix, said two phase matrix consisting essentially of a first phase and a second intergranular phase, said first phase consisting essentially of crystalline silicon nitride, said second intergranular phase consisting essentially of silicon nitride and a densification aid, said two phase matrix containing less than 3 weight percent aluminum oxide, said densified composite ceramic article having a density greater than 99% of theoretical density, a high abrasion resistance, a high hardness, a fracture toughness equal to or greater than 4 MN/m 3/2 , and a resistance to oxidation at temperatures greater than 1200° C.
Claim 12
Dependent Claim
30 words
A densified composite ceramic cutting tool in accordance with claim 9 wherein said hard refractory boride is selected from the groups consisting of titanium boride, hafnium boride and combinations thereof.
Claim 13
Dependent Claim
31 words
A densified composite ceramic cutting tool in accordance with claim 9 wherein said hard refractory boride comprises from about 1 to about 60 volume percent of said composite ceramic cutting tool.
Claim 14
Dependent Claim
31 words
A densified composite ceramic cutting tool in accordance with claim 9 wherein said hard refractory boride comprises from about 15 to about 50 volume percent of said composite ceramic cutting tool.
Claim 15
Dependent Claim
38 words
A densified composite ceramic cutting tool in accordance with claim 9 wherein said densification aid is selected from the group consisting of yttrium oxide, cerium oxide, hafnium oxide, zirconium oxide, the rare earth lanthanide oxides, and mixtures thereof.
Claim 16
Dependent Claim
30 words
A densified composite ceramic cutting tool in accordance with claim 9 wherein said densification aid comprises from about 1 to about 25 weight percent of said composite ceramic cutting tool.
Claim 17
Dependent Claim
24 words
A densified composite ceramic cutting tool in accordance with claim 9 wherein the particle size of said hard refractory is below about 20 microns.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-03-16 | 1990-09-15 | 1991-03-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-03-16 | 1994-09-15 | 1995-03-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-03-16 | 1998-09-15 | 1999-03-17 | $7700.00 | Window Closed / Lapsed |