Patent US5006491A successfully refreshed from Google Patents.
US5006491A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for production of nitride ceramic shapes
Assignee: Taiyo Yuden Co Ltd
•
Filing: 1989-03-21
•
Granted: 1991-04-09
•
Expires: 2009-03-21
Abstract
Abstract There is first prepared a mixture of a nitride ceramic material (e.g. aluminum nitride) and a sintering aid (e.g. calcium carbonate), both in finely divided form. Admixed with a binder, the mixture is pressed into moldings of desired shape. The moldings are sintered to maturity in a nitrogenous atmosphere. The sintered moldings are subsequently aftertreated by being exposed to fluorine or its compound at a reduced temperature in the range of, typically, 1000° to 1600° C. The aftertreatment eliminates undesired intergranular substances from the sintered moldings and thus improves their thermal conductivity.
Inventors
- 👤 Syuusaku Ueda
- 👤 Masayuki Fujimoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 07:11
CPC Classifications
C; C04; C04B; C04B41/00; C04B41/009; C04B35/00; C04B35/515; C04B35/58; C04B35/581; C04B41/53; C04B41/5338; C04B41/5346; C04B41/80; C04B41/91
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
89 words
A process for the fabrication of nitride ceramic products which comprises: (a) preparing a mixture of a nitride material and a sintering aid, both in finely divided form; (b) forming the mixture into moldings of desired shape; (c) sintering the moldings to maturity in a nitrogenous atmosphere, the sintered moldings having undesirable intergranular substances; and (d) aftertreating the sintered moldings by exposing the sintered moldings to an atmosphere containing at least either of fluorine and a fluoride at an elevated temperature so as to remove the undesirable intergranular substances.
Claim 2
Dependent Claim
89 words
A process for the fabrication of nitride ceramic products which comprises: (a) preparing a mixture of a nitride material and a sintering aid, both in finely divided form; (b) forming the mixture into moldings of desired shape; (c) sintering the moldings to maturity in a nitrogenous atmosphere, the sintered moldings having undesirable intergranular substances; and (d) aftertreating the sintered moldings by exposing the sintered moldings to an atmosphere containing at least either of fluorine and a fluoride at an elevated temperature so as to remove the undesirable intergranular substances.
Claim 3
Dependent Claim
34 words
The process of claim 1 wherein the moldings are sintered to maturity at a first temperature, and wherein the sintered moldings are aftertreated at a second temperature that is lower than the first temperature.
Claim 4
Dependent Claim
23 words
The process of claim 2 wherein the sintered moldings are aftertreated on being allowed to cool from the first to the second temperature.
Claim 5
Dependent Claim
30 words
The process of claim 2 wherein the sintered moldings are allowed to cool from the first temperature to room temperature and then reheated to the second temperature for the aftertreatment.
Claim 6
Dependent Claim
12 words
The process of claim 1 wherein the nitride material is aluminum nitride.
Claim 7
Dependent Claim
23 words
The process of claim 1 wherein the sintering aid is selected from the group consisting of calcium carbonate, aluminum oxide, and yttrium oxide.
Claim 8
Dependent Claim
20 words
The process of claim 1 wherein the sintered moldings are aftertreated in a temperature range of 900° to 2000° C.
Claim 9
Dependent Claim
20 words
The process of claim 1 wherein the sintered moldings are aftertreated in a temperature range of 1000° to 1600° C.
Claim 10
Dependent Claim
115 words
A process for the fabrication of nitride ceramic products which comprises: (a) preparing a mixture of a nitride material and a sintering aid in finely divided form; (b) molding the mixture into desired shape; (c) placing the molding of the mixture within a furnace; (d) sintering the moldings to maturity by heating the sintered molding to a first temperature within the furnace filled with nitrogenous gas, the sintered moldings having undesirable intergranular substances; (e) changing the furnace temperature to a second temperature that is lower than the first temperature; and (f) aftertreating the sintered moldings by introducing a gaseous tetrafluoromethane into the furnace at the second temperature so as to remove the undesirable intergranular substances.
Claim 11
Dependent Claim
115 words
A process for the fabrication of nitride ceramic products which comprises: (a) preparing a mixture of a nitride material and a sintering aid in finely divided form; (b) molding the mixture into desired shape; (c) placing the molding of the mixture within a furnace; (d) sintering the moldings to maturity by heating the sintered molding to a first temperature within the furnace filled with nitrogenous gas, the sintered moldings having undesirable intergranular substances; (e) changing the furnace temperature to a second temperature that is lower than the first temperature; and (f) aftertreating the sintered moldings by introducing a gaseous tetrafluoromethane into the furnace at the second temperature so as to remove the undesirable intergranular substances.
References Cited (Backward Citations)
US3591668A
Cited
US3786124A
Cited
US4435513A
Cited
US4753763A
Cited
EP0166073A2
Cited
US4698320A
Cited
US4711861A
Cited
US4746637A
Cited
US4719187A
Cited
US4810479A
Cited
US4810679A
Cited
US4857140A
Cited
US4877482A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-04-08 | 1994-10-08 | 1995-04-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-04-08 | 1998-10-08 | 1999-04-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-04-08 | 2002-10-08 | 2003-04-09 | $7700.00 | Window Closed / Lapsed |