Alloy powders for magnetic recording tape

A new process for making acicular Fe-Co alloy particles for high density recording tapes and for master tapes of magnetic contact printing is presented. The method consists of adsorption of Co(OH)
2
colloid on the surface of fine goethite particles, heat treatment at 700°C in air to diffuse Co++ into the particles, followed by reduction to the metallic alloy state. The alloy powders with 10 to 50 atm % of Co showed coercive force higher than 1000 Oe and saturation magnetization greater than 160 emu/g. The characteristics of new alloy powder tapes prepared by the adsorption method are measured and comparison with those of CrO
2
and γ-Fe
2
O
3
tapes are given.