Effect of annealing treatment on the wear properties of ni rich niti alloy coatings

Abstract

In the present study, NiTi alloy coatings were deposited onto AISI 316L stainless steel substrates using the Closed Field Unbalanced Magnetron Sputtering (CFUBMS) system. The as-deposited NiTi alloy coating was Ni rich NiTi alloy with a composition of 44.1 at. % of Ti and 55.9 at. % of Ni and demonstrated an amorphous structure. The post-annealing treatment of the as-deposited Ni rich NiTi alloy coating was successfully produced a crystalline structure. The as-deposited and the annealed Ni rich NiTi alloy coatings were characterized to determine the effect of the annealing process on their wear properties. The Ni rich NiTi phases and structure were determined by XRD. Wear morphology was investigated using the pin-on-disk wear test. The existence of a TiO2 rutile layer with a combination of the Ni3Ti and NiTi B-2 parent phases, that formed during the annealing process produced a significant improvement over the wear performance compared to the as-deposited Ni rich NiTi SMA coating. The post-sputtered annealing process at the annealing temperatures of 550 degrees C for a period of 60 minutes and 600 degrees C for a period of 30 minutes succeeded in increasing the adhesion and wear resistance of the Ni rich NiTi coating. The findings show the potential the post-sputtering annealing process in creating an excellent structure of NiTi coating which demonstrates significant wear resistance properties for tribological applications.