Research On Property Of CrN Coating Deposited On TC4 Alloy By Double-Cathode Glow Discharge Technique

The application scope of titanium alloy is very big,and is very common in the aerospace industry,architecture,medicine and petrochemical industry.Advantages include good biocompatibility,high specific strength,low density,and excellent corrosion resistance and superior biocompatibility.However,titanium alloy has many deficiencies,such as the high temperature oxidation resistance is not good,poor wear resistance etc.the application has been limited by the surface modification technology to improve the performance of titanium alloy,it has become an effective way the properties for titanium alloys.Transtent subgroup metal nitride Coatings is becoming a hot spot of research in contemporary material surface coating.due to their excellent properties including highly microhardness,low friction coefficients and good wear resistance.As a kind of new hardness coating,CrN coating have emerged as alternative in machining aplication due to thermal stability,low deposition temperature,excellent corrosion resistance and good wear resistance.In this paper,CrN coatings with high cohesion and good synthetical properties have been successfully prepared on the TC4 alloy substrate to improve its performance using double-cathode glow discharge technique.The phase compositions,microstructure and chemical composition of the as-deposited coatings were examined by a X-ray diffractometer(XRD),Scanning electron microscope and X-ray energy spectrum are used together.Mechanical properties of the as-deposited coatings were were examined by a nanoindentation tester(NHT)equipped with a Berkovich diamond tip and micro--hardness meter,scratch tester and ball-on-discfriction tester.The electrochemical behavior of the as-deposited coatings in a 3.5 wt.% NaCl solution was characterized by electrochemical techniques.The XRD results showed that CrxN films were consisted of single CrN phase.The cross-sectional SEM morphology indicated that the films of thickness is thicker;The CrN coatings,which are nearly 16 um thick,have high binding force with TC4 alloy substrates.According to the test results of mechanical properties,the coating hardness and toughness increased significantly.The results of wear tests indicate that the CrN coating have superior wear resistance than TC4 alloy substrate.In 3.5%NaCl solution related experiments,the CrN coating evidently improves the corrosion resistance of TC4 alloy substrates.