US4066426A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of forming a glass-reacted-ceramic with cadmium
Assignee: MRA Laboratories Inc
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Filing: 1976-11-01
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Granted: 1978-01-03
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Expires: 1996-11-01
Abstract
Abstract A method for forming a cadmium-containing glass-reacted-ceramic body is described. This material is advantageously employed as the dielectric material in a capacitor. The method comprises mixing a barium-titanate alkaline-earth-metal-zirconate powder with glass powder, forming a cake or layer of the powder mix and firing the cake at from 1600° to 2050° F in a controlled cadmium containing atmosphere to sinter and densify the material. The cake is buried in an inert powder to which has been added a cadmium oxide powder to supply a source of cadmium external of the cake and to control the cadmium containing atmosphere during firing. Cadmium ions diffuse, during sintering, into the glass and further, into the ceramic grains to promote grain growth and to downwardly shift the Curie temperature.
Inventors
- 👤 Galeb H. Maher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 15:55
CPC Classifications
H; H01; H01B; H01B3/00; H01B3/02; H01B3/08; H01B3/085; C; C04; C04B; C04B35/00; C04B35/01; C04B35/46; C04B35/462; C04B35/465; C04B35/468; C04B35/4682; H01G; H01G4/00; H01G4/002; H01G4/018; H01G4/06; H01G4/08; H01G4/12; H01G4/1209; H01G4/1236; H01G4/1245
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
144 words
A method for making a glass-reacted-ceramic body comprising mixing a major proportion of a finely ground ceramic comprised of barium titanate and an alkaline-earth-metal zirconate and a minor proportion of a pulverized low temperature glass; forming a cake of said mixture; placing a quantity of cadmium oxide powder adjacent to said cake; and firing said cake and said cadmium oxide powder at a temperature of between 1600° F to 2050° F so that said cadmium oxide powder provides during said firing a controlled and enriched cadmium atmosphere external of said cake to transform said cake during said firing into a sintered body and to cause cadmium ions from said cadmium of said atmosphere to react with said ceramic and to diffuse into the titanate lattice thereof, whereby grain growth in said body is enhanced and the Curie temperature of said body is shifted downwardly.
Claim 2
Independent Claim
144 words
A method for making a glass-reacted-ceramic body comprising mixing a major proportion of a finely ground ceramic comprised of barium titanate and an alkaline-earth-metal zirconate and a minor proportion of a pulverized low temperature glass; forming a cake of said mixture; placing a quantity of cadmium oxide powder adjacent to said cake; and firing said cake and said cadmium oxide powder at a temperature of between 1600° F to 2050° F so that said cadmium oxide powder provides during said firing a controlled and enriched cadmium atmosphere external of said cake to transform said cake during said firing into a sintered body and to cause cadmium ions from said cadmium of said atmosphere to react with said ceramic and to diffuse into the titanate lattice thereof, whereby grain growth in said body is enhanced and the Curie temperature of said body is shifted downwardly.
Claim 3
Dependent Claim
71 words
The method of claim 1 additionally comprising preparing a homogenous mixture of an inert powder selected from the group of zirconium oxide and calcium titanate and mixture thereof and said cadmium oxide powder, wherein said placing is accomplished by burying said cake prior to said firing in a pile of said inert powder mixture, said inert powder being inert at said firing temperature with respect to said cadmium and said cake.
Claim 4
Dependent Claim
27 words
The method of claim 2 wherein said inert powder consists of zirconium oxide, wherein calcium titanate is substituted for up to 50 percent of said zirconium oxide.
Claim 5
Dependent Claim
25 words
The method of claim 2 wherein said cadmium oxide in said inert powder amounts to from 1% to 14% by weight of said inert powder.
Claim 6
Dependent Claim
37 words
the method of claim 4 wherein said low temperature glass contains approximately 30% by weight cadmium oxide and said cadmium oxide in said inert powder amounts to from 1% to 6% by weight of said inert powder.
Claim 7
Dependent Claim
31 words
The method of claim 4 wherein said low temperature glass contains less than 10 weight percent cadmium oxide and said firing of said buried cake is accomplished on an open slab.
Claim 8
Dependent Claim
50 words
The method of claim 4 wherein said low temperature glass contains less than 10 weight percent cadmium oxide, said cadmium oxide in said inert powder amounts to from 3 to 7.5 weight percent of said inert powder, and said firing of said buried cake is accomplished in a closed crucible.
Claim 9
Dependent Claim
37 words
The method of claim 1 wherein said mixing includes adding an organic binder to said ceramic and said glass, and said method additionally comprises heating said cake prior to said firing to burn off said organic binder.
Claim 10
Dependent Claim
39 words
The method of claim 1 wherein said glass contains at least 20% by weight of cadmium oxide and said firing of said cake with said cadmium oxide powder is effected in a closed crucible for more than 3 hours.
Claim 11
Dependent Claim
17 words
The method of claim 9 wherein said temperature of firing is from 1600° F to 1764° F.
Claim 12
Independent Claim
140 words
A method for making a glass-reacted-ceramic body comprising mixing a major proportion of a finely ground ceramic comprised of barium titanate and an alkaline-earth-metal zirconate and a minor proportion of a pulverized low temperature glass; forming layers of said glass-ceramic mixture; coating said layers with an electroding paste, stacking said electroded layers to form a cake; placing a quantity of cadmium oxide powder adjacent to said cake; and firing said cake and said cadmium oxide powder at a temperature of between 1600° and 2050° F so that said cadmium oxide powder provides during said firing a controlled and enriched cadmium atmosphere external of said cake to transform said cake during said firing into a sintered body and to cause cadmium ions from said cadmium of said atmosphere to react with said ceramic and to diffuse into the titanate lattice thereof.
Claim 13
Independent Claim
140 words
A method for making a glass-reacted-ceramic body comprising mixing a major proportion of a finely ground ceramic comprised of barium titanate and an alkaline-earth-metal zirconate and a minor proportion of a pulverized low temperature glass; forming layers of said glass-ceramic mixture; coating said layers with an electroding paste, stacking said electroded layers to form a cake; placing a quantity of cadmium oxide powder adjacent to said cake; and firing said cake and said cadmium oxide powder at a temperature of between 1600° and 2050° F so that said cadmium oxide powder provides during said firing a controlled and enriched cadmium atmosphere external of said cake to transform said cake during said firing into a sintered body and to cause cadmium ions from said cadmium of said atmosphere to react with said ceramic and to diffuse into the titanate lattice thereof.
Claim 14
Dependent Claim
15 words
The method of claim 11 wherein said electroding paste is comprised of silver and palladium.
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) | 1981-01-02 | 1981-07-04 | 1982-01-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-01-02 | 1985-07-04 | 1986-01-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-01-02 | 1989-07-04 | 1990-01-03 | $7700.00 | Window Closed / Lapsed |