Cyanide- and cyanate-free nitriding agent - for preparing and regenerating nitriding baths, contains dicyandiamide, urea and carbonate

摘要

A cyanide- and cyanate-free agent for salt bath nitriding comprises (by wt.) 40-70% dicyandiamide, 20-40% urea and 10-30% alkali metal carbonate. To prepare the fused salt bath, the agent is melted with a 1:1 mixt. of alkali metal carbonates to give a bath contg. 1-20 (pref. 10-16)% carbonate. The organic cpds. in the agent convert the carbonates into active cyanate without the necessity for bath aeration, so that the bath has a long working life and no separate regeneration agents are required. Violent reaction of the organic cpds. at the bath surface when adding the agent for bath regeneration, is reduced by incorporation of carbonate in the agent.