Research Of Laser Machining And Friction Property Regular Surface Micro Texturing

As the development of tribology theories and experimental research, regular surface micro texturing as a controllable technique ,which can remarkably improve surface tribological performance, has been the focus for the international research increasingly. It has significant value of research and application prospect for designing suitable surface micro pattern to study the different kinds of regular surface micro patterns and its tribological performance.Laser surface texturing (LST) has been one of the most successful ways in surface texturing because of its good performance such as high speed, non pollution and excellent control ability for shape and size. The chief work of my paper includes that comparing the machining quality between nanosecond and picosecond laser texturing, studying a suitable LST for industry application, designing three kinds of micro patterns for laser texturing and comparing their tribological performance.In this dissertion, firstly a mathematic model of heat exchange and temperature field during laser machining is established based on vested theoretical research. It offers theoretical instruction for the subsequent research in laser surface texturing byYAG and Nd: YVO₄. Secondly, a contrast test is given to analyze the differencesbetween nanosecond laser surface texturing and picosecond laser surface texturing. WYKO profile testing instrument and SEM (JXA-840A, the USA) are chosen to character the crater micro-structure in two different laser machining methods. The result shows that: because of the larger pulse width, nanosecond laser texturing has a longer contact time with work material, and then forms larger heat-affected zone and produces serious damage zone. These damage zones would bring repeating hot melting and resolidification, come into being split and residue. Contrarily, ultrashort laser pulse-picosecond laser texturing could conquer this phenomenon, carry out cold-working and improve the machining quality remarkably. Thirdly, three kinds of micro patterns are designed for laser texturing. Then an experimental device—UMT-2 is used to conduct comparative experiments among three kinds of micro patterns in picosecond laser texturing and untextured surface. It includes dry friction test and lubrication test. The effect to surface friction behavior caused by microstucture is analyzed through studying the trend of friction coefficient under different lubricated conditions, loads and micro patterns. The result shows that: on the condition of dry friction and low load, the tribological performance of textured surface improves remarkably comparing with untextured surface, the crater has the best tribological performance among three micro patterns ; In the case of lubrication and low load , an improvement in tribological performance could be achieved. But it didn't have a obvious difference in steady-state value, similarly, the crater had the best tribological performance among three micro patterns.