Research On The Surface Properties Of Titanium Alloy By Rotary Ultrasonic Milling

Titanium alloy is widely used in aerospace,ship,automobile,chemical industry due to its low density,high specific strength,good corrosion resistance and fatigue resistance.However,the high friction coefficient,sensitivity to adhesion wear and fretting wear,poor wear resistance and so on,limit the application of titanium alloy to a certain extent.At present,with the rapid development of aerospace industry,the demand of titanium alloy is increasing day by day,and the requirement of its surface tribological properties is also increasing.Because rotary ultrasonic milling process can produce micro-pit surface with certain texture,which has strong similarity with fish scale structure,so it can improve the friction performance of materials.Therefore,the experiment of rotary ultrasonic milling of Ti-6Al-4V titanium alloy is carried out.Moreover,the experiment of friction and wear properties is analyzed.In addition,the experiment of PVD coating properties of titanium alloys is also analyzed.Firstly,the experiment of rotary ultrasonic milling is designed,and the effects of spindle speed,feed speed and ultrasonic current on the 3D roughness of titanium alloy surface and the structure of surface micro-pits are analyzed.The result shows that when the ultrasonic current is 100 mA,it can obtain better 3D roughness parameters,and the quality of micro-pits on the surface is high.When the ultrasonic current is larger or smaller,the surface morphology is both closer to that of the traditional milling.In addition,the size of single micro-pit increases with the increase of spindle speed and feed speed,and the effect of spindle speed on 3D roughness is more significant than feed speed.Secondly,the experiment of friction and wear properties are carried out.The effects of different processing parameters on the surface friction coefficient,wear volume and wear morphology of titanium alloy are analyzed,also with wear experimental parameters.The results show that the surface of the rotary ultrasonic can reduce the friction coefficient and wear volume,and the effect of spindle speed on the friction coefficient and the wear volume is more obvious than the feed rate.In addition,when the ultrasonic current is 100 mA,the wear marks have neat edges,narrow scratches,fewer deposits,and the continuous distribution of furrows.Finally,the experiment of PVD coating is carried out.The coating properties of titanium alloy specimens under different milling parameters are analyzed,from the aspects of section morphology and bonding strength.The results show that TiAlN coating can be deposited in micro-pits on the surface of titanium alloy by rotary ultrasonic milling.The rotary ultrasonic milling process is more conducive to the combination of TiAlN coating and titanium alloy substrate,and the improvement of bonding performance by feed speed is more significant than that by spindle speed.