TREATMENT OF FERROUS METAL PARTS TO INCREASE RESISTANCE TO WEAR AND SEIZURE

摘要

A method of surface-hardening mechanical parts of ferrous metals by introducing into the surface layers of the treated parts a plurality of elements chosen from the groups consisting of nitrogen and carbon; nitrogen, carbon and sulphur, nitrogen, carbon, sulphur and phosphorus; in which said parts to be treated are immersed in a bath of molten salts at a temperature of 450 DEG to 600 DEG C., said bath being of the kind comprising CO3-- and CNO- ions on the one hand and on the other hand alkaline ions comprising Li+, K+ and Na+ ions. The bath may further comprise sulphur anions chosen from the group consisting of S--, SO3-- and S2O3--, and also PO3- phosphorus ions. A regenerating agent comprising urea is further introduced into said bath in order to convert excess CO3-- ions to CNO- ions, and an apparatus is described for carrying this method into effect.