Study On Properties Of Nb₂N Syntheiszed By Double Caheode Plasma Technique

Titanium alloy is widely used in the aerospace,watercraft and biomedical fields for its low density,high strength and biocompatibility.But it is also easy to be wear,easily oxidized,easily occurs corrosion in ions aqueous solution of halogen.Those shortcomings limit its application.Using the surface modification technology to deposite hard coating on Titanium alloy surface can improve its physical and chemical propertie.This technology has become the most effective and widely used method.As a new kind of hard coating,Nb N is widely used in the materials,chemical,mechanical,electronic components fields because of its high hardness,high melting point,good wear resistance and corrosion resistance.The research about Nb N coating is mainly focused on its superconducting properties,electrical properties and preparation technics at present,but the research about its wear resistance and corrosion resistance is rare.This article selects the double cathode sputtering deposition technology syntheticing Nb₂N layer on the TC4 surface.Using a XRD,SEM and EDS to characterize the structure of the coating produced.Using scratches test,microhardness test,friction and wear testing machine to determine mechanical behavior of the coating.Corrosion behavior of Nb₂N was determined by potentiodynamic polarization and electrochemical impedance spectroscopy,using coatings immersed in simulated seawater for different periods of time,then compared with TC4 titanium alloy matrix.The conclusions are as follows:?1?The surface of coating is smooth with no loose hole and preferentially grown along the?002?crystal.The coating is about 21?m and metallurgical bond with the matrix,and its critical load value achieves 78.2 N.The average hardness of the coating is 1784.44 HV,and no cracks were induced in the toughness test,which indicated that the coating had high hardness and good toughness.At room temperature and load of 150 g,the friction coefficient of the coating is about 0.4 and there is no obvious crack around the wear mark in the friction and wear test which shows good wear resistance.?2?The steady-state value of open circuit potential of Nb₂N is higher and sooner reached than that of titanium alloy in 3.5wt.%Na Cl solution.In the polarization curve test,the corrosion current density of the coating is about one order of magnitude lower and the corrosion potential is 0.36 V higher.In electrochemical impedance measurement,the arc value of the coating and the maximum phase angle are obviously larger than that of the substrate.The maximum value is wider than that of the titanium alloy substrate.And with the prolongation of immersion time,the properties of the coating did not change obviously,but the properties of titanium alloy matrix decreased obviously.The results of corrosion resistance test show that the coating has better corrosion resistance than titanium alloy matrix and plays an obvious role in protecting the matrix.