"Cobaloy," a new cobalt-based magnetic particle for tape

Cobaloy is an alloy particle consisting mainly of cobalt coprecipitated with nickel and iron as the oxalate. Careful pyrolytic reduction permits control of coercive force from 600 to 1200 Oe within ±50 Oe. Cobaloy particles are about 0.05 micron long with a length-to-diameter ratio of 2 or 3 to 1. Controlled oxidation of the particle surfaces to about 10% of particle weight markedly reduces pyrophoricity and increases resistance to oxidation. Tape made from Cobaloy particles shows improved high-frequency response resulting from higher coercive force and increased remanence.