Palladium-silver electrical resistance alloy - which can be cast, rolled and drawn into wire with very low temp. coefft. of resistance over wide temp. range

摘要

The alloy contains by wt. 55.5-6-.6% Pd and 39.4-44.5% Ag and unavoidable impurities. The temp. coefft. of electrical resistance (TCR) at -50 to +730 deg.C is +/- 20 x 10 power minus 6/deg.C. A pref. alloy contains 56.1-59.1% Pd and 43.9-40.1% Ag, with a TCR of (+) (-) 10 x 10 power minus 6/deg.C over the range -50 to +600 deg.C. The alloy is pref. made by melting, and then converting the melt by hot and cold working into thin sheet or wire. This is given a recrystallisation anneal of 2 seconds to 100 hrs. at 500-110 deg. C in air, a non-oxidising atmos., or vacuo. Finally slow cooling is carried out to remove internal stress and attain the desired TCR. The annealed wire or sheet may be coated with insulation, coiled, and reheated to 200-500 deg.C to remove internal stress and attain the required TCR. Used esp. as a search coil in an eddy current meter, where the alloy has a low specific resistance, low TCR, and can easily be rolled, deformed, drawn and coiled. The search coil is used in inspection, crack-detection, or monitoring fuel nozzles in rockets.