Surface Wettability Research Of Micro-textured YG6 Cemented Carbide Processed By Femtosecond Laser

In high-speed cutting,micro-textured tools could improve the surface wettability,increase the lubrication effect and decrease the tool wear.Different types of micro-pits arrays on YG6 surface were processed by femtosecond pulsed laser in the paper.The influence of processing parameters on micro-texture morphology and the mechanism of contact angle were investigated.The main contents and conclusion are as follows:(1)The incubation effect on YG6 surface irradiated with femtosecond laser pulse was investigated with the classical ablation threshold computing method.The results show that the ablation threshold of YG6 decreases with the increase of shot number,which presents obvious incubation effects.The theoretical equations of multi-pulsed ablation threshold and ablation diameter are obtained.Among the equations,the incubation coefficient is 0.84±0.02 and the single-shot ablation threshold is 1.14±0.06J/cm~2.(2)The influence of laser average power,shot number and micro-pits spacing on cone-shaped micro-pits morphology and surface contact angle were investigated.Based on Wenzel state,the geometrical morphology model of micro-pits array surface was established to analyze the influence mechanism of surface morphology on contact angle.The results show that as average power or shot number increases,the variation of micro-pits diameter accords with the ablation diameter equation,the depth initially grows linearly and then slows down.The surface contact angle decreases.As micro-pits spacing increases,the contact angle gradually increases.The analysis results of the surface morphology model show that the contact angle and Wenzel contact angle satisfy the same Slogistic curve relation under the three conditions.The contact angle equation fitted by the curve establishes the relationship between contact angle and morphology parameters,and explains the influence of surface morphology on contact angle.(3)The influence of laser average power and scanning times on the morphology of cylindrical micro-pits,and that of micro-pits density and single micro-pit area on the contact angle of four shapes of cylindrical micro-pits array which are square,circle,regular triangle and hexagon.Based on Wenzel state,the geometrical morphology models of the four surfaces were established to analyze the mechanism of contact angle.The results show that the shape of cylindrical micro-pit is good with the average power under 200mW.The depth of cylindrical micro-pits is linearly correlation with the scanning times.The contact angles of the four surfaces all decrease with the increase of micro-pits density,and increase with the increase of single micro-pit area,and the shapes of the four surfaces,in order of wettability,are regular triangle,square,regular hexagon and circle.The analysis results of the model based on Wenzel state show that the contact angle and Wenzel contact angle approximately satisfy the same Slogistic curve relation under different micro-pits densities or single micro-pit areas.The contact angle equation fitted by the curve establishes the relationship between contact angle and morphology parameters,and explains the influence of micro-pits structure on contact angle and the mechanism of the order of the wettability among four surfaces.