Protection of steel against corrosion - by hot treatment with chromo-sulphuric acid followed by heating in non-oxidising atmos.

摘要

The process, mainly for use on stainless steel, consists of (a) treating the surface with hot chromo-sulphuric acid, and (b) thermal treatment in a non-oxidising atmos. at 900-1000 deg.C, so as to obtain a chromic oxide coating of 0.2 micron thickness with good adhesion and hardness and improved resistance to corrosive gases.