Tribological Performance Of Amphiphobic Titanium Alloy In Different Lubrications

Titanium alloys are widely used in the field of marine engineering,however,the poor tribological properties limit its potential.To improve the friction performance of titanium alloy in different lubricating medium,laser processing technology and sol-gel method coated SiO2 nano-powders was used to change the wettability of the surfaces of Ti6A14V alloy to prepare both hydrophobic and oleophobic Ti6A14V alloy surface.Tribological properties of these samples were evaluated in water,seawater and oil,respectively.The main research results are shown as follows:Modified the smooth titanium alloy sample with low surface energy and coated it with SiO2 could increase the contact angle and prepare the amphiphobic titanium alloy surface,but could not achieve to superamphiphobic state.The amphiphobic surface improves the friction performance of the Ti6Al4V alloys.Compared to vacancy,the friction coefficient of amphiphobic surface coated with SiO2 reduce by 10.9%,9.6%and 22.2%,and the wear loss reduce by 53.8%,19.7%and 52.7%under water,seawater and oil lubrication,respectively.The textured surfaces with grid or dot micro-structure built by laser processing show better amphiphobic performance after being modified by low surface energy and coated with SiO2.The amphiphobic property of sample with grid micro-structure is better than that of dot,while the micro-structure depth of 50 ?m is better than that of 20?m.The samples which have grid micro-structure with depth of 50 ?m and coated with SiO2 have the best amphiphobic performance.The contact angle of water droplets is 169.0° and the rolling angle is 1.5°,while it changed to 160.2° and 4.2° for the seawater droplets,respectively.Thereby the surface belonged to super-hydrophobic surface which conformed to Cassie model.On the other hand,the contact angle of oil droplets is 127.9° and the oil droplets cannot roll on the surface,indicating the surface belonged to oleophobic surface which conformed to Wenzel model.Compared with the smooth surface which modified by low surface energy and coated with SiO2,the tribological properties of the amphophibic surface with grid and dot micro-structure are better.The friction coefficient of amphophibic surface with grid micro-structure is larger while the wear loss is smaller than that with dot micro-structure.Compared with the vacancy,the decrease of friction coefficient of amphophibic surface with dot micro-structure depth of 50 ?m and coated with SiO2 reduce by 32.7%,36.5%,42.2%,the decrease of wear loss of amphophibic surface with grid micro-structure depth of 50 ?m and coated with SiO2 reduce by 87.1%,61.4%,95.9%,under water,seawater and oil,respectively.The friction coefficient of amphophibic surface in seawater is smaller,while the wear loss is larger than that in water.The wear mechanism is adhesive wear in seawater,while it is abrasive wear in water.The study indicates that the preparation of amphophibic surface can greatly enhance the frictional behavior of titanium alloy in water,seawater and oil lubrication,respectively.This study provides a new method and technical support to improve the frictional performance of titanium alloy.