Assessments on corrosion, tribological and impact fatigue performance of Ti- and TiN-coated stainless steels by plasma surface alloying technique

In this work, Ti and TiN coatings were deposited on AISI316L stainless steel (SS) substrates by plasma surface alloying technique. The morphology, composition and structure were investigated by SEM, GDOES and XRD. The corrosion properties of Ti and TiN coatings were investigated in a simulated body fluid (SBF) environment. Friction and wear behaviors of SS substrates and Ti and TiN coatings were measured using a ball-on-disk type tribometer under sliding against Si3N4 counterparts under boundary lubricated conditions with either normal saline or SBF. The ball-on-plate impact tests were conducted on the coatings under a constant force of 800 N for 10,000 impacting cycles. The results indicate that the Ti and TiN coatings could achieve a higher corrosion polarization resistance and a more stable corrosion potential in the SBF environment than the uncoated stainless steel substrate SS316L. The Ti and TiN coatings also exhibited an excellent wear resistance and chemical stability during the sliding tests against Si3N4 ball in normal saline and SBF environment. The tested samples showed different wear mechanisms in the sliding tests. Compared to the Ti coatings, the TiN coatings had a better compatibility with the Si3N4 ball. However, the impact tests showed that the fatigue cracks and the coatings' chipping occurred on the TiN coatings but not on the Ti coatings.