Method of blackening surfaces of steel parts with wet nitrogen

摘要

A gaseous mixture of nitrogen and water vapor (dew point of about -8 DEG to 32 DEG C.), heated to 550 DEG to 750 DEG C., contacts the surfaces of a steel part for a sufficient time to produce adherent, deep-black layers on the part. Steel aperture masks and support frames for color television picture tubes may be blackened by the novel method.