Effect On Performance Of Nitride Coatings With Textured Substrate Surface As Pretreatment

The design idea of the coating with a pretreatment that a laser textures matrix surface is proposed in the paper,and this pretreatment is developed combined micro-nano textures with PVD coating.The matrix surface texturing which changes the smooth matrix surface into rough,can increase contact area and wettability of the matrix surface and is good for coating adhering.In addition,comparing with the coating which pretreatment is blasting,we can research the coating with matrix surface texturing about morphology,mechanical properties and tribological behavior and analyze the mechanism.Based on the effects about coating pretreatments,the design principals of the matrix surface texturing,as a new pretreatment,is proposed.Firstly,using four different methods for coating pretreatment;(1)micro textures are fabricated by nanosecond laser:the pulse power of 10 W,scanning speed of 50 mm/s and one-time scanning;(2)nano textures are fabricated by femtosecond laser;(3)the tool is blasted for the matrix surface's pretreatment;(4)the tool is only abraded and polished for pretreatment.Nitride coatings(AlCrN,TiAIN and TiN)are successfully deposited by PVD technology on the four different matrix surface,thus the coated tools are developed:the coated tools with micro scale textured matrix surface,named MCT;the coated tools with nano scale textured matrix surface,named NCT;the coated tool with blasting of matrix surface,named BCT;the coated tool with polishing of matrix surface,named PCT.The effect of surface texturing on the mechanical properties of the nitride coating is studied.Results show that matrix surface texturing can not only increase the roughness of matrix,but also enhance the H/E ratio.The formation of oxidation material which results from laser ablation is appearing approximately at the close position of the nitride peaks.The adhesion strength between coating and matrix is better than that of standard tool because of the change of mechanical anchoring mechanisms and the incensement of matrix contact area.The effect of the tribological properties of nitride coated samples in sliding against GCr15 ball bearing steel is studied.The following results are obtained:NCT sample has a wider grinding crack compared with BCT and PCT sample,and also shows a higher wear life.The conclusion directly shows that the NCT sample has a better adhesion strength.For MCT sample,micro scale textures don't effectively relieve the wear,the textures can't reach the best surface roughness and quality.The recast from laser ablation contact with friction ball firstly and lead to the worse wear of the ball.