Research On Microstructure And Wear Resistance Of Ni-Ti Coating Prepared By Arc Spraying

Two kinds of Ni-Ti coatings, HVAF-NiTi coating and Ar-NiTi coating, were prepared on2Crl3martensitic stainless steel substrate through high velocity air-f\iel arc spraying and plainarc spraying protected by argon atmosphere. The phase composition of the coatings wasinvestigated by XRD (X-ray Diffraction); the microstructures of the coatings were analyzed bySEM (Scanning Electron Microscope) and EDS (Energy Dispersive Spectrometer); themicrohardness of the coatings was also determined; the abrasive and erosive resistance of thecoatings was studied by rubber wheel abrasion tester and erosion tester; the wear resistance ofthe coatings was compared with2Crl3substrate, and the wear mechanism was also analyzed.The results show that the coatings are inhomogeneous, and to some degree, there aresome pores, unmelted particles, microcracks，oxides, and residual stress; the microhardness ofthe coatings increases sharply compared with the spraying mateiral, but also lfuctuates greatly;the oxides are mainly TiO and NiO, and the HVAF-NiTi coating has a higher oxides content;the NiTi (B2) austenite phase predominates in the coatings, and the Ar-NiTi coating has ahigher NiTi (B2) phase content; the NiTi (B19’) martensite phase in the oirginal sprayingmateiral disappears in the coatings because of high temperature in the sparying process; bothof the coatings have a much better abrasive resistance than the substrate, although Ar-NiTicoating’s microhardness is a little lower, yet its abrasive resistance is a little better thanHVAF-NiTi coating; the erosive wear of HVAF-NiTi coating shows the characteristics ofbirttle materials，while Ar-NiTi coating ductile mateirals; Ar-NiTi coating’s erosive resistanceis a little worse than the substrate, but improves sharply when it is compared with HVAF-NiTicoating.