Composite thermostat material

Claim 1

A composite thermostat material comprising a first outer layer of a first preselected metallic alloy having a relatively high coefficient of thermal expansion, a second outer layer of a second preselected metallic alloy having a relatively lower coefficient of thermal expansion than said first preselected metallic alloy, and an intermediate layer comprising a copper alloy having a resistivity between approximately 10 to 30 ohms per circular mil foot and having a substantially constant resistance to deformation with respect to temperature up to a temperature of approximately 500*C. selected from the group consisting of an alloy consisting essentially of, by weight, approximately 0.15 percent zirconium and the balance copper, an alloy consisting essentially of, by weight, approximately 0.95 percent chromium and the balance copper, and an alloy consisting essentially of, by weight, approximately 0.5 percent tellurium, 0.007 percent phosphorous and the balance copper, said first outer layer having a thickness between approximately 5 to 45 percent of the total thickness of said composite material and said second outer layer having a thickness between approximately 35 to 50 percent of the total thickness of said composite material, said first and second outer layers being bonded to respective opposite sides of said intermediate layer which has a thickness of approximately 5 to 60 percent of the total thickness of said composite material, said first preselected metallic alloy consisting essentially of, by weight, approximately 72 percent manganese, 18 percent copper, and 10 percent nickel, said second preselected metallic alloy consisting essentially of, by weight, approximately 35 1/2 to 36 1/2 percent nickel and the balance iron, said composite material having a flexivity of between approximately 100 X 10 7 to 160 X 10 7 inch per inch per degree Fahrenheit and a resistivity of between approximately 15 to 100 ohms per circular mil foot.