Effect of feeding method for industrial gases during high-temperature carbonitriding of articles
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Impregnation of surface layers with nitrogen during high-temperature carbonitriding in an endothermic atmosphere depends on the input method and the rate of ammonia to the charge of articles being impregnated. The greatest content of residual ammonia, and consequently the content of nitrogen in the carbonitrided layer, is observed with input of ammonia through an injector and with an increase in the rate of its input to the surface of articles being impregnated from 180 to 250 m/sec.
The injector system developed for feeding industrial gases into the furnace space of a muffleless unit provides a reduction in scatter of layer thickness, content of carbon and nitrogen at the surface, and it makes it possible with an ammonia input of 10–12% of the gas carrier to obtain impregnation of surface layers with nitrogen to a depth of 0.05–0.6 mm up to 0.8–1.0 and to 0.3–0.5% respectively, and also to increase by 30–40% the rate of carbonitrided layer growth.
KeywordsNitrogen Atmosphere Ammonia Furnace Surface Layer
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