Study on microstructural and tribological properties of sulphonitrocarburized layers diffused by hollow cathode discharging

Abstract

In the present research, sulfurized, nitrided, nitrocarburized, and sulphonitrocarburized layers were diffused on the investigated specimens by hollow cathode diffusion, which was introduced as a new surface treatment method due to its numerous advantages over traditional diffusion methods. The structural morphologies, composition, phase structure, and tribological properties of different diffused layers were analyzed. It was found that both the sulfurized and sulphonitrocarburized layers were relatively porous compared with the other two diffused layers, especially the grain size and the microscopic roughness of the sulphonitrocarburized layer were much smaller than those of the sulfurized layer. The sulphonitrocarburized layer had the highest nano-hardness, the lowest friction coefficient, wear loss, and the smallest wear spot of the counterparts, which is superior over nitrided layer, nitrocarburized layer, and sulfurized layer. It benefited from the synergistic effect of the sulfurized layer and the nitrocarburized layer. This paper is significant for the protection of high-load high-speed friction pair s, exceptionally soft-hard pairs.