Silver electrical contact materials and method of making
AssigneeGibson Electric, Inc.
InventorsRichard C. Bevington, David J. Snee
Life of this patent
Estimating the term…
Abstract
Electrical contact material of silver or mixtures of silver and a thermally decomposable compound of silver having an additive of an alkali metal, for example lithium, added in the form of a salt prior to sintering to increase the as-sintered density of the resulting material and to aid in the prevention of undesirable surface blisters. The silver material may be fabricated as a backing layer on a primary contact material of silver-cadmium oxide.
Claims20
A method for preparing silver material comprising
- forming a compact of a mixture of particles of silver or particles of silver and a thermally decomposable compound of silver together with an additive selected from the group consisting of lithium nitrate, strontium nitrate, and cesium nitrate;
- heating said compact to a temperature below the final sintering temperature for a period of time sufficient to decompose said additive;
- and
- sintering said heated compact.
A method for preparing silver material comprising
- forming a compact comprising a mixture of finely-divided particles of silver or finely-divided particles of silver and a thermally decomposable compound of silver together with lithium nitrate so that lithium constitutes 0.01 to 0.05 percent by weight of the mixture;
- heating said compact at about 600.degree. to 700.degree. C for about20 minutes to 1 hour to decompose said lithium nitrate and to drive off entrapped gases and volatile impurities;
- and
- heating said compact at about 850.degree. to 950.degree. C for about 1/2 to 21/2 hours to form a sintered silver compact.
A compact comprising a mixture of finely-divided particles of silver or finely-divided particles of silver and a thermally decomposable compound of silver and an additive selected from the group consisting of lithium, nitrate, strontium nitrate, and cesium nitrate wherein lithium, strontium, or cesium constitutes about 0.003 to 0.1 percent by weight of the mixture.
A method for preparing contact elements comprising
- forming a compact of particles of a primary contact material and a layer of a mixture of particles of silver or particles of silver and a thermally decomposable compound of silver together with an additive selected from the group consisting of lithium nitrate, strontium nitrate, and cesium nitrate;
- heating said compact to a temperature below the final sintering temperature for a period of time sufficient to decompose said additive;
- and
- sintering said heated compact to form a sintered bi-layer element of a primary contact material and a backing layer of dense silver.
A method for preparing contact elements comprising
- forming a compact of particles of a primary contact material containing silver and a layer of a mixture of particles of silver or particles of silver and a thermally decomposable compound of silver together with lithium nitrate so that lithium constitutes 0.01 to 0.05 percent by weight of the mixture;
- heating said compact at about 600.degree. to 700.degree. C for about 20 minutes to 1 hour to decompose said lithium nitrate and to drive off entrapped gases and volatile impurities;
- and
- heating said compact at about 850.degree. to 950.degree. C for about 1/2 to 21/2 hours to form a sintered bi-layer contact element of a primary material containing silver and a backing layer of dense silver.
A bi-layer compact comprising
- a layer of finely-divided particles of a primary contact material containing silver;
- and
- a layer of mixture of finely-divided particles of silver or finely-divided particles of silver and a thermally decomposable compound of silver and an additive selected from the group consisting of lithium nitrate, strontium nitrate, and cesium nitrate wherein lithium, strontium, or cesium constitutes about 0.003 to 0.1 percent by weight of the mixture.
Dependencies are inferred from the claim text.