Effect Of Textured Substrate Surface Pretreated By Laser On The Properties Of AlCrN Coatings

The coating can improve the wear resistance,corrosion resistance and fatigue resistance of mechanical parts.The pretreatment of the substrate surface can improve the surface properties of the coating.The commonly used substrate surface pretreatment methods mainly include:nitriding treatment,cryogenic treatment,and sandblasting treatment.However,the coating-substate interface structure of the above pretreatment is uncontrollable.The coating is easy to peel off and failure.In view of the above problems,in this paper,coating techonlogy and laser surface texturing technology are combined together.The effect of laser texturing pretreatment on the substrate surface on the performance of AlCrN coating is investigated.By using laser texturing pretreatment on the substrate surface,the coating is coated on the laser textured substrate surface with regular morphology and adjustable microstructure instead of on the smooth surface.The laser texturing pretreatment can achieve precise control the interface structure.The preparation process of substrate surface with microstructure can be controlled.The physical vapor deposition method is used.The AlCrN coating is prepared on the laser texturing pretreated substrate surface.The microstructure,mechanical properties,and friction and wear properties of the AlCrN coating with laser texturing pretreated substrate surface are studied.This paper provides an important theoretical basis for the development of a new coating substrate surface pretreatment method.The surface of the cemented carbide substrate is pretreated by laser surface texturing using nanosecond laser.The generation of microstructure on substrate surface is studied with different laser processing parameters.The modification of mechanical properties in the near surface area is investigated.The effect of laser texturing pretreatment on the surface morphology and composition of subastrate surface is explored.The influence of laser texturing preatement on the surface integrity of substrate material is investigated.The results are as follows.A regular fish-scale like microstructure can be formed on the substrate surface by using laser surface texturing pretreatment.The microstructure morphology can be controllable adjusted by changing laser processing parameters.The instantaneous high temperature is generated by the plused laser during laser texturing pretreatment process.The binder phase Co is evaporated.The binder phase Co reacts with the residual O2 in the processing chamber to form CoO compunds.The residual stress on the polished surface is compressive stress.In contrast,the residual stress on the laser texturing pretreatment surface is tensile stress.The laser texturing pretreatment leads to the increase of the Vickers hardness.The residual tensile stress on the laser texturing pretreated surface can be significantly reduced by applying sandblasting.The Vickers hardness on the laser texturing pretreated surface can also be improved by using sandblasting.The scratch performance of the substrate surface after laser texturing pretreatment is systematically studied.The scratch performance of polished surface is used as a comparision.The results are as follows.A groove with a certain width and depth is formed on the scratch surface.The substrate material is piled up on the sides of the scratch.The scratch width,the groove depth,and the scratch cross-sectional area AW are increased on the laser texturing pretreated surface compared with that on the polished surface.The scratch hardness of the laser texturing pretreated surface is slightly decreased compared with that on the polished surface.The scratch performance of laser texturing pretreated surface can be improved by sandblasting.The scratch depth of the laser texturing pretreated surface can be reduced,and the scratch hardness can be increased by adjusting sandblasting time.The AlCrN coating is prepared on the laser texturing pretreated surface by using PVD coating technology.The effect of laser texturing pretreatment of substrate surface on the performance of AlCrN coating is systematically studied.The results are as follows.The morphology of the AlCrN coating on the laser texturing pretreated surface shows a fish-scale like microstructure.The interface between the coating and the substrate presents a sinusoidal shape.The interface is well bonded.The coating thickness is about 3 μm.The residual stress of AlCrN coatings on different laser texturing pretreated surface is compressive residual stress.The residual compressive stress of AlCrN coating increases with the increase of the laser power.The residual compressive stress of AlCrN coating decreases with increase of pulse coincidence.The hardness and elastic modulus of AlCrN coating increase with the increase of laser power and pulse coincidence.The AlCrN coating on the polished surface flakes off inside the scratch.Large flakes appear at the edge of the scratch.The AlCrN coating on the laser texturing pretreated surface is discretized by fish scale texture.The peeling off of the AlCrN coating on the laser texturing pretreated surface is mainly concentrated in the area of a single scale area.The spalled area of the AlCrN coating on the laser texturing pretreated surface is significantly reduced compared with that on the polished surface.The laser texturing pretreatment of the substrate surface can significantly improve the spalling resistance of the AlCrN coating.The friction and wear characteristics of laser texturing preatreated surface and AlCrN coatings on laser texturing pretreated surface are studied.The results are as follows.The friction coefficients on the polished surface and on the laser texturing preatreated surface have little difference.The main wear form of the polished surface is the fragmentation and damage of the WC particles in the matrix.The wear mechanism is fatigue wear.The fish-scale like microstructure on the laser texturing pretreated surface micro-cuts the stainless steel ball when compared with the polished surface.The stainless steel material is mainly adhered to the raised parts of the fish-scale like microstructure.The wear mechanism is adhesive wear.The AlCrN coating on the laser texturing pretreated surface has a fish-scale like microstructure.The fish-scale like microstructure micro-cuts the stainless steel ball.The fish-scale like microstructure of the AlCrN coating on the laser texturing pretreated surface makes the peeling area of the AlCrN coating mainly concentrated in a single scale range.The fish-scale like microstructure can inhibit the expansion of the peeling range of the AlCrN coating and improve the anti-peeling property of the AlCrN coating.