METHOD FOR ECOLOGICALLY CLEAN PROCESS OF CARBONITRIDING OF METAL PRODUCTS Russian patent published in 1995 - IPC

FIELD: carbonitriding. SUBSTANCE: method for ecologically clean process of carbonitriding of metal products includes production of endothermal controlled atmosphere by catalytic conversion of hydrocarbon gas with oxidizer (air) and supply of the atmosphere to space of carbonitriding with addition of hydrocarbon gas C_nH_2n+2 and ammonia in the amount of (1-5)/ 100n and (1-6)/100n of volume of supplied atmosphere. Used atmosphere is withdrawn from carbonitriding space through tight channel, and together with additional amount of hydrocarbon gas and oxidizer is returned to conversion, and hydrogen content increase is compensated in used atmosphere by replacing a part of oxidizer with carbon dioxide in the amount of (0,8-1,1)_nN by volume of addition of hydrocarbon gas and (1,3-1,7)_nN/(n+1) of addition of ammonia, where N is return factor expressed by ratio of volumes of atmosphere removed from carbonitriding space and supplied to it. EFFECT: higher efficiency.