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US3986822A Expired / Lapsed US ⏱️ 0.0 years remaining

Boron nitride crucible

Assignee: Praxair ST Technology Inc
•
Filing: 1975-02-27
•
Granted: 1976-10-19
•
Expires: 1995-02-27
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Abstract

Abstract A boron nitride crucible, suitable for the vaporization of aluminum, having a multi-walled structure comprising an outer wall and a thinner inner wall weakly bonded to the thicker outer wall. Because of this structure, the crucible is considerably more flexible than conventional single-walled crucibles and exhibits substantially improved thermal cycling characteristics and longer life. The crucible is produced by depositing pyrolytic boron nitride upon a mandrel having the shape of the desired crucible at a temperature of from about 1850° C. to about 2100° C. until a first layer of boron nitride of suitable thickness has been produced, interrupting the deposition of boron nitride upon the mandrel and lowering the temperature to below 1750° C., and then depositing additional boron nitride upon the mandrel at a temperature of from about 1850° C. to about 2100° C. to produce a second outer layer of boron nitride having a thickness greater than that of the inner layer.

Inventors

  • 👤 Robert William Lashway

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-23 18:32
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/583; C23; C23C; C23C14/00; C23C14/22; C23C14/24; C23C14/243; C23C16/00; C23C16/01

Claims Analysis

Total Claims: 8
Claim 1
Independent Claim 38 words
A pyrolytic boron nitride crucible, suitable for the vaporization of aluminum, having a multi-walled structure comprising an outer wall of pyrolytic boron nitride and a thinner inner wall of pyrolytic boron nitride laminated to the thicker outer wall.
Claim 2
Dependent Claim 38 words
A pyrolytic boron nitride crucible, suitable for the vaporization of aluminum, having a multi-walled structure comprising an outer wall of pyrolytic boron nitride and a thinner inner wall of pyrolytic boron nitride laminated to the thicker outer wall.
Claim 3
Dependent Claim 33 words
A crucible as in claim 1 wherein the thickness of the inner wall of the crucible is about 50 per cent to about 75 per cent of the thickness of the outer wall.
Claim 4
Dependent Claim 37 words
A crucible as in claim 2 wherein the crucible has an inner diameter of from 2.5 cm. to 7.6 cm. and the thickness of the inner wall of the crucible is between 0.025 cm. and 0.076 cm.
Claim 5
Dependent Claim 73 words
A pyrolytic boron nitride crucible, suitable for the vaporization of aluminum, having a multi-walled structure comprising an outer wall of pyrolytic boron nitride, an inner wall of pyrolytic boron nitride, and at least one intermediate wall of pyrolytic boron nitride, said walls being laminated to each other, said outer wall being of greater thickness than the inner and intermediate walls, and said intermediate walls being of no greater thickness than the inner wall.
Claim 6
Dependent Claim 73 words
A pyrolytic boron nitride crucible, suitable for the vaporization of aluminum, having a multi-walled structure comprising an outer wall of pyrolytic boron nitride, an inner wall of pyrolytic boron nitride, and at least one intermediate wall of pyrolytic boron nitride, said walls being laminated to each other, said outer wall being of greater thickness than the inner and intermediate walls, and said intermediate walls being of no greater thickness than the inner wall.
Claim 7
Dependent Claim 33 words
A crucible as in claim 4 wherein the thickness of the inner wall of the crucible is about 50 per cent to about 75 per cent of the thickness of the outer wall.
Claim 8
Dependent Claim 37 words
A crucible as in claim 5 wherein the crucible has an inner diameter of from 2.5 cm. to 7.6 cm. and the thickness of the inner wall of the crucible is between 0.025 cm. and 0.076 cm.

References Cited (Backward Citations)

US3063865A Cited
US3227431A Cited
US3717498A Cited
US3649734A Cited
US3724996A Cited
US3734480A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1979-10-19 1980-04-19 1980-10-19 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1983-10-19 1984-04-19 1984-10-19 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1987-10-19 1988-04-19 1988-10-19 $7700.00 Window Closed / Lapsed

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