Preparation And Wear Properties Of Cr/CrXN(X=Al,Si) Multilayer Coatings On Titanium Alloys

In order to improve the properties and its service life of titanium alloy,Cr/CrN,Cr/CrAlN and Cr/CrSiN multilayer coatings with different periods were prepared on the surface of Ti-6Al-4V titanium alloy by multi-arc ion plating.In this paper,X-ray diffractometer?XRD?,X-ray photoelectron spectroscopy?XPS?,scanning electron microscope?SEM?,transmission electron microscope?TEM?,Rockwell indentation,microhardness tester and erosion resistance tester were applied to study the microstructure,morphology,adhesive strength,hardness,tribiology performance and erosion resistance of the coatings.The corresponding results are as follows:?1?The phases of Cr/CrN multi-layer coatings are CrN,Cr₂N phases and a small amount of Cr phase,among which the Cr/CrN-1 coating is comprised of CrN phase and shows the preferential growth on the?111?plane;the main phases of Cr/CrAlN multilayer coatings are?Al,Cr?N phase and Cr phase;the main phases of Cr/CrSiN multilayer coatings are CrN phase and Cr phase,and the Si elements in the coating existed mainly in the form of Si-N bonding.?2?Cr/CrN coating has high hardness and adhesive strength?HF-1?.The hardness of Cr/CrAlN coating is further improved and show better adhesive strength?HF-1^HF-2?.The hardness of Cr/CrSiN coating is the highest of all the coatings,but show the poor adhesive strength.Among the Cr/CrSiN coatings,the Cr/CrSiN-1coating has the poorer adhesive strength with the grade of HF-6.With the increase of circulations,the adhesive strength of the coating increases,and the adhesive strength of Cr/CrSiN-10 coating is HF-1.?3?Results of friction and wear experiments shows that Cr/CrN,Cr/CrAlN and Cr/CrSiN coatings shows better wear resistance compared with the substrate.With the addition of Al and Si elements,the wear resistance of the coatings have been further improved compared with Cr/CrN coating.The friction coefficient and wear rate of Cr/CrSiN coating are the lowest among the three coatings.Also,the wear resistance of Cr/CrSiN coatings increase with increasing the circulations.?4?Erosion wear results show that Cr/CrAlN coatings have the best erosion resistance among the three series of coatings,among which Cr/CrAlN-1 coating shows the best erosion resistance.The failure mechanism of Cr/CrN and Cr/CrAlN coating is brittle fatigue spalling.For Cr/CrN coatings,Cr/CrN-5 coating has the better erosion resistance.The erosion failure mechanism of Cr/CrSiN coating is different from the Cr/CrN and Cr/CrAlN coatings.In the process of erosion,microcracks were generated at the interface between Cr/CrSiN coating and the substrate,and the multi-layer structure interrupted the propagation of the cracks to the surface.