US3887412A
Expired / Lapsed
US
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Method of making a triple density silicon nitride article
Assignee: Ceradyne Inc
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Filing: 1973-12-20
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Granted: 1975-06-03
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Expires: 1993-12-20
Abstract
Abstract A method of making a triple density article of silicon nitride is disclosed. A first element is formed by hot pressing silicon nitride particles. The general shape of a second element is formed by injection molding silicon metal particles and a binder and subsequently burning out the binder. The general shape of a third element is slip cast adjacent and in bonding relationship to at least a portion of the second element. The so combined second and third elements are nitrided in a nitriding operation. Facing surface areas of the first element and the third element are bonded together by applying heat to both elements and pressure to at least one of the elements while the other element is held in a fixed position.
Inventors
- 👤 Karsten H Styhr
- 👤 Andre Ezis
- 👤 Michael U Goodyear
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 00:09
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C04B35/593; C04B35/591; F; F01; F01D; F01D5/00; F01D5/12; F01D5/28; F01D5/284
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
298 words
A method of making a triple density article of silicon nitride which comprises the steps of: compacting a mixture consisting of from about 95 to 99.5% by weight silicon nitride particles and from about 5 to 0.5% by weight of a densification aid to at least 98% of theoretical density by use of heat and pressure thereby to form a first element of silicon nitride; forming the general shape of a second element by (a) injection molding silicon metal particles and a carrier to form the general shape of said second element, and (b) heating said second element to burn out said carrier; forming the general shape of a third element in physical association with the general shape of said second element by slip casting said third element adjacent to at least a portion of said second element, said slip casting being accomplished from a slip containing silicon metal particles suspended in a vehicle; nitriding said second and said third elements in a single operation so that both of said elements are converted substantially to pure silicon nitride and are joined to one another at the area of slip casting contact; bringing a surface area of said first element into close association with a surface area of said third element; holding said associated surfaces of said first and said third elements so they do not move with respect to one another; and forming a bond between said associated surfaces of said first and said third elements by applying heat on all the elements and pressure on at least one of said elements while the other of said elements is held thereby to force a portion of the silicon nitride forming said surface area of said one element into bonding relationship with said surface area of the other element.
Claim 2
Independent Claim
298 words
A method of making a triple density article of silicon nitride which comprises the steps of: compacting a mixture consisting of from about 95 to 99.5% by weight silicon nitride particles and from about 5 to 0.5% by weight of a densification aid to at least 98% of theoretical density by use of heat and pressure thereby to form a first element of silicon nitride; forming the general shape of a second element by (a) injection molding silicon metal particles and a carrier to form the general shape of said second element, and (b) heating said second element to burn out said carrier; forming the general shape of a third element in physical association with the general shape of said second element by slip casting said third element adjacent to at least a portion of said second element, said slip casting being accomplished from a slip containing silicon metal particles suspended in a vehicle; nitriding said second and said third elements in a single operation so that both of said elements are converted substantially to pure silicon nitride and are joined to one another at the area of slip casting contact; bringing a surface area of said first element into close association with a surface area of said third element; holding said associated surfaces of said first and said third elements so they do not move with respect to one another; and forming a bond between said associated surfaces of said first and said third elements by applying heat on all the elements and pressure on at least one of said elements while the other of said elements is held thereby to force a portion of the silicon nitride forming said surface area of said one element into bonding relationship with said surface area of the other element.
Claim 3
Independent Claim
298 words
A METHOD OF MAKING A TRIPLE DENSITY ARTICLE OF SILICON NITRIDE WHICH COMPRISES THE STEPS OF: COMPACTING A MIXTURE CONSISTING OF FROM ABOUT 95 TO 99.5% BY WEIGHT SILICON NITRIDE PARTICLES AND FROM ABOUT 5 TO 0.5% BY WEIGHT OF A DENSIFICATION AID TO AT LEAST 98% OF THEORETICAL DENSITY BY USE OF HEAT AND PRESSURE THEREBY TO FROM A FIRST ELEMENT OF SILICON NITRIDE, FORMING THE GENERAL SHAPE OF A SECOND ELEMENT BY (A) INJECTION MOLDING SILICON METAL PARTICLES AND A CARRIER TO FORM THE GENERAL SHAPE OF SAID SECOND ELEMENT, AND (B) HEATING SAID SECOND ELEMENT TO BURN OUT SAID CARRIER, FORMING THE GENERAL SHAPE OF A THIRD ELEMENT IN PHYSICAL ASSOCIATION WITH THE GENERAL SHAPE OF SAID SECOND ELEMENT BY SLIP CASTING SAID THIRD ELEMENT ADJACENT TO AT LEAST A PORTION OF SAID SECOND ELEMENT, SAID SLIP CASTING BEING ACCOMPLISHED FROM A SLIP CONTAINING SILICON METAL PARTICLES SUSPENDED IN A VEHICLE, NITRIDING SAID SECOND AND SAID THIRD ELEMENTS IN A SINGLE OPERATION SO THAT BOTH OF SAID ELEMENTS ARE CONVERTED SUBSTANTIALLY TO PURE SILICON NITRIDE AND ARE JOINED TO ONE ANOTHER AT THE AREA OF SILIP CASTING CONTACT, BRINGING A SURFACE AREA OF SAID FIRST ELEMENT INTO CLOSE ASSOCIATION WITH A SURFACE AREA OF SAID THIRD ELEMENT, HOLDING SAID ASSOCIATED SURFACES OF SAID FIRST AND SAID THIRD ELEMENTS SO THEY DO NOT MOVE WITH RESPECT TO ONE ANOTHER, AND FORMING A BOND BETWEEN SAID ASSOCIATED SURFACES OF SAID FIRST AND SAID THIRD ELEMENT BY APPLYING HEAT ON ALL THE ELEMENTS AND PRESSURE ON AT LEAST ONE OF SAID ELEMENTS WHILE THE OTHER OF SAID ELEMENTS IS HELD THEREBY TO FORCE A PORTION OF THE SILICONE NITRIDE FORMING SAID SURFACE AREA OF SAID ONE ELEMENT INTO BONDING RELATIONSHIP WITH SAID SURFACE AREA OF THE OTHER ELEMENT.
Claim 4
Independent Claim
298 words
A METHOD OF MAKING A TRIPLE DENSITY ARTICLE OF SILICON NITRIDE WHICH COMPRISES THE STEPS OF: COMPACTING A MIXTURE CONSISTING OF FROM ABOUT 95 TO 99.5% BY WEIGHT SILICON NITRIDE PARTICLES AND FROM ABOUT 5 TO 0.5% BY WEIGHT OF A DENSIFICATION AID TO AT LEAST 98% OF THEORETICAL DENSITY BY USE OF HEAT AND PRESSURE THEREBY TO FROM A FIRST ELEMENT OF SILICON NITRIDE, FORMING THE GENERAL SHAPE OF A SECOND ELEMENT BY (A) INJECTION MOLDING SILICON METAL PARTICLES AND A CARRIER TO FORM THE GENERAL SHAPE OF SAID SECOND ELEMENT, AND (B) HEATING SAID SECOND ELEMENT TO BURN OUT SAID CARRIER, FORMING THE GENERAL SHAPE OF A THIRD ELEMENT IN PHYSICAL ASSOCIATION WITH THE GENERAL SHAPE OF SAID SECOND ELEMENT BY SLIP CASTING SAID THIRD ELEMENT ADJACENT TO AT LEAST A PORTION OF SAID SECOND ELEMENT, SAID SLIP CASTING BEING ACCOMPLISHED FROM A SLIP CONTAINING SILICON METAL PARTICLES SUSPENDED IN A VEHICLE, NITRIDING SAID SECOND AND SAID THIRD ELEMENTS IN A SINGLE OPERATION SO THAT BOTH OF SAID ELEMENTS ARE CONVERTED SUBSTANTIALLY TO PURE SILICON NITRIDE AND ARE JOINED TO ONE ANOTHER AT THE AREA OF SILIP CASTING CONTACT, BRINGING A SURFACE AREA OF SAID FIRST ELEMENT INTO CLOSE ASSOCIATION WITH A SURFACE AREA OF SAID THIRD ELEMENT, HOLDING SAID ASSOCIATED SURFACES OF SAID FIRST AND SAID THIRD ELEMENTS SO THEY DO NOT MOVE WITH RESPECT TO ONE ANOTHER, AND FORMING A BOND BETWEEN SAID ASSOCIATED SURFACES OF SAID FIRST AND SAID THIRD ELEMENT BY APPLYING HEAT ON ALL THE ELEMENTS AND PRESSURE ON AT LEAST ONE OF SAID ELEMENTS WHILE THE OTHER OF SAID ELEMENTS IS HELD THEREBY TO FORCE A PORTION OF THE SILICONE NITRIDE FORMING SAID SURFACE AREA OF SAID ONE ELEMENT INTO BONDING RELATIONSHIP WITH SAID SURFACE AREA OF THE OTHER ELEMENT.
Claim 5
Dependent Claim
34 words
The method of claim 1 wherein: said first element is the one element to which pressure is applied to force its surface area into bonding relationship with said surface area of said third element.
Claim 6
Dependent Claim
12 words
The method of claim 1 wherein: said densification aid is magnesium oxide.
Claim 7
Dependent Claim
40 words
The method of claim 1 wherein: said compacting operation takes place at a temperature from of about 1,650*C to about 1, 800*C at a pressure of from at least 3000 psi and for a time of at least 1.5 hours.
Claim 8
Dependent Claim
40 words
The method of claim 1 wherein: said bond forming operation takes place at a temperature of fRom about 1,625*C to about 1, 700*C at a pressure of at least 1,000 psi and for a time of at least 1.5 hours.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-06-02 | 1978-12-02 | 1979-06-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-02 | 1982-12-02 | 1983-06-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-02 | 1986-12-02 | 1987-06-03 | $7700.00 | Window Closed / Lapsed |