EP0082371A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Sintered silicon nitride ceramic articles having surface layers of controlled composition
Assignee: Verizon Laboratories Inc
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Filing: 1982-12-03
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Granted: —
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Expires: 2002-12-03
Abstract
Abstract Sintered silicon nitride-silica-yttria ceramic articles having silica-rich or yttria-rich casing layers are disclosed. The surface layers are formed by sintering pre-compacted bodies in a powder setter bed to produce unitary sintered bodies having surface layers in which the atom ratio of yttrium to silicon has a smooth gradient from the surface of the article to the interior body of the article.
Inventors
- 👤 Anthony P. Moschetti
- 👤 J. Thomas Smith
- 👤 Carr Lane W. Quackenbush
- 👤 Helmut Lingertat
- 👤 Vincent W. Nehring
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 12:57
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584; Y; Y10; Y10T; Y10T428/00; Y10T428/26
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
84 words
A unitary, sintered, polycrystalline silicon nitride based article including an interior body portion and a surface layer portion, said article comprising a major phase consisting essentially of silicon nitride and a minor phase consisting essentially of compounds of silicon, yttrium, nitrogen, and oxygen wherein the atom ratio of yttrium to silicon in said minor phase of said surface layer portion of said article differs from the atom ratio of yttrium to silicon in said minor phase of said interior body portion of said article.
Claim 2
Dependent Claim
84 words
A unitary, sintered, polycrystalline silicon nitride based article including an interior body portion and a surface layer portion, said article comprising a major phase consisting essentially of silicon nitride and a minor phase consisting essentially of compounds of silicon, yttrium, nitrogen, and oxygen wherein the atom ratio of yttrium to silicon in said minor phase of said surface layer portion of said article differs from the atom ratio of yttrium to silicon in said minor phase of said interior body portion of said article.
Claim 3
Dependent Claim
70 words
An article in accordance with claim 1 wherein said interior body portion consists essentially of a composition lying within the region of a silicon nitride-silicon dioxide-yttrium oxide ternary composition diagram, said region bounded by the lines 80 mole percent silicon nitride and 95 mole percent silicon nitride; 2 mole percent silicon dioxide and 10 mole percent silicon dioxide; and 2 mole percent yttrium oxide and 15 mole percent yttrium oxide.
Claim 4
Dependent Claim
57 words
An article in accordance with claim 2 wherein said surface layer portion includes compositions lying within the triangular region of said ternary composition diagram, said region bounded by the lines 0 mole percent yttrium oxide, 48 mole percent silicon nitride, and the line defining the molar ratio of yttrium oxide to silicon dioxide equal to about 2.
Claim 5
Dependent Claim
85 words
A unitary, sintered, polycrystalline silicon nitride based article including an interior body portion and a surface layer portion, said article comprising a major phase consisting essentially of silicon nitride and a minor phase consisting essentially of compounds of silicon, yttrium, nitrogen, and oxygen wherein the atom ratio of yttrium to silicon in said minor phase of said surface layer portion of said article is less than the atom ratio of yttrium to silicon in said minor phase of said interior body portion of said article.
Claim 6
Dependent Claim
85 words
A unitary, sintered, polycrystalline silicon nitride based article including an interior body portion and a surface layer portion, said article comprising a major phase consisting essentially of silicon nitride and a minor phase consisting essentially of compounds of silicon, yttrium, nitrogen, and oxygen wherein the atom ratio of yttrium to silicon in said minor phase of said surface layer portion of said article is less than the atom ratio of yttrium to silicon in said minor phase of said interior body portion of said article.
Claim 7
Dependent Claim
70 words
An article in accordance with claim 4 wherein said interior body portion consists essentially of a composition lying within the region of a silicon nitride-silicon dioxide-yttrium oxide ternary composition diagram, said region bounded by the lines 80 mole percent silicon nitride and 95 mole percent silicon nitride; 2 mole percent silicon dioxide and 10 mole percent silicon dioxide; and 2 mole percent yttrium oxide and 15 mole percent yttrium oxide.
Claim 8
Dependent Claim
57 words
An article in accordance with claim 5 wherein said surface layer portion includes compositions lying within the triangular region of said ternary composition diagram, said region bounded by the lines 0 mole percent yttrium oxide, 48 mole percent silicon nitride, and the line defining the molar ratio of yttrium oxide to silicon dioxide equal to about 2.
Claim 9
Dependent Claim
76 words
A unitary, sintered, polycrystalline silicon nitride based article including an interior body portion and a surface layer portion, said article comprising a major phase consisting essentially of silicon nitride and a minor phase consisting essentially of compounds of silicon, yttrium, nitrogen, and oxygen wherein the atom ratio of yttrium to silicon in said article is greater than the atom ratio of yttrium to silicon in said minor phase of said interior body portion of said article.
Claim 10
Dependent Claim
76 words
A unitary, sintered, polycrystalline silicon nitride based article including an interior body portion and a surface layer portion, said article comprising a major phase consisting essentially of silicon nitride and a minor phase consisting essentially of compounds of silicon, yttrium, nitrogen, and oxygen wherein the atom ratio of yttrium to silicon in said article is greater than the atom ratio of yttrium to silicon in said minor phase of said interior body portion of said article.
Claim 11
Dependent Claim
70 words
An article in accordance with claim 7 wherein said interior body portion consists essentially of a composition lying within the region of a silicon nitride-silicon dioxide-yttrium oxide ternary composition diagram, said region bounded by the lines 80 mole percent silicon nitride and 95 mole percent silicon nitride; 2 mole percent silicon dioxide and 10 mole percent silicon dioxide; and 2 mole percent yttrium oxide and 15 mole percent yttrium oxide.
Claim 12
Dependent Claim
57 words
An article in accordance with claim 8 wherein said surface layer portion includes compositions lying within the triangular region of said ternary composition diagram, said region bounded by the lines 0 mole percent yttrium oxide, 48 mole percent silicon nitride, and the line defining the molar ratio of yttrium oxide to silicon dioxide equal to about 2.
Claim 13
Dependent Claim
47 words
An article in accordance with claim 9 wherein said atom ratio of yttrium to silicon in said surface layer portion is characterized by a smooth gradient from a maximum at the surface of said article to a minimum adjacent to said interior body portion of said article.
References Cited (Backward Citations)
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