Pulse laser-induced cell-like texture on surface of titanium alloy for tribological properties improvement

Abstract

In order to improve the surface tribological properties of TC4 titanium alloy, this paper used laser processing technology to prepare a cell-like texture on TC4 surface. The cells of cell-like texture were separated by regular cracks caused by recasting of TC4, which could be got at the parameters of 1 μm distance of adjacent laser spots and 2.5 μm patch of adjacent laser paths with a certain laser power density. The laser treatment increased the surface microhardness from 351 to 445 HV. The relationship between tribological properties of TC4 and the laser power density was studied. At 0.32 GW/cm2, under the lubricant of simulated body fluid (SBF), the average friction coefficient between TC4 and UHMWPE reduced significantly by 32.4%, and the wear rate of UHMWPE ball decreased by 59%, compared with the original surface. The cell-like texture could increase the transmission speed of the lubricant at the friction interface by three times with the help of capillary force, and it could also store lubricant in the texture to improve the tribological performance. The channels around cells were assumed to be rectangular groove. The width of the channel which was observed with a 3D confocal microscope was 3.2 μm, and the capillary force produced by a single rectangular groove was calculated.