Abstract: Rare earth induced ion nitriding test was carried out on Cr12 steel. The hardness and depth of the nitrided layer on the specimen surface were measured by microhardness tester, and the phases of the nitrided layer were analyzed by means of XRD. Finally, the friction and wear characteristics of the specimen surface were quantified by friction testing machine. The results indicate that rare earth can affect the effect of ion sputtering nitriding on the Cr12 steel, and the effect decreases sharply with the increase of the distance between them. When the distance is less than 25 mm, the surface hardness of the specimen is obviously lower than that of the ordinary ion nitriding, and the surface friction coefficient and wear rate are also slightly worse, but the thickness of nitriding layer is significantly increased. When the distance exceeds 25 mm, the induction effect of rare earth declines significantly, but the hardness and frictional coefficient of the specimen surface are basically the same as those of ordinary ion nitriding. Meanwhile, the wear rate is obviously increased. The analysis shows that rare earth elements can increase the adsorption capacity of nitrogen ions on the specimen surface and provide path advantages for their infiltration. When the distance between them is too large, rare earth ions are not easy to be adsorbed on the specimen surface, and the rare earth induction effect is disappeared. Meantime, it also causes lattice defects on the surface of the specimen, which reduces the wear resistance of the surface.

Key words: rare earth element, Cr12 steel, ion nitriding, friction and wear