Process for stabilizing ferromagnetic chromium dioxide.

摘要

This invention relates to a process for stabilizing ferromagnetic chromium dioxide in respect of water and oxidable organic compounds which it may contact in the magnetic tapes.

This process is applicable to a starting Cr0<Sub>2</Sub> having good magnetic properties, i.e. a coercive force not lower than about 400 Oersted, a maximum magnetic induction Bm not lower than about 2500 gauss and a magnetic induction Br not lower than about 1600 gauss. Cr0<Sub>2</Sub> is subjected to a heat treatment at a temperature ranging from 300 to 390°C in the presence of a gas stream not exerting any oxidizing or reducing action on the compounds of trivalent, tetravalent and hexavalent chromium. Suitable gases are, for example, nitrogen, helium and argon.