Mechanical behavior of nitrided 316L austenitic stainless steel coated with a:C-H-Si

摘要

The austenitic stainless steel AISI 316L is used in chemical and other industries due to its good corrosion properties; however, it has a poor wear resistance. Plasma assisted treatments such as diffusion process and/or coatings can be used in order to improve the tribological properties. The a:C-H-Si coatings have low friction coefficient and wear resistance; in addition, they are chemically inert although they present adhesion problems when they are deposited on metallic substrates. In this work, the mechanical behavior and adhesion of the a:C-H-Si coatings deposited on nitrided AISI 316L stainless steel (duplex sample) and without nitriding (coated sample) were studied. The coatings were characterized by EDS and Raman. The hardness and Young Modulus were assessed with nanoindentation. The microstructure of the nitrided layer and the coatings was analysed by OM, SEM-FIB and XRD. Pin on disk and linear sliding tests were carried out. The adhesion was evaluated using Indentation Rockwell C and Scratch test. The coatings had high hydrogen content, over 40%, and the film thickness was about 20 μm. The hardness was about 13 GPa and Young's Modulus was 73 GPa. The friction coefficient was less than 0.2 and the wear resistance was better than in stainless steel without any treatment. In the linear sliding tests, the track depth in the duplex and coated samples was six times lower than in the untreated sample. The nitriding had influence on the adhesion; the critical load was 16.2 N in the duplex sample and of 9.6 N in the coated sample. In the indentation Rockwell C test, the duplex sample also had better adhesion than the only coated sample.