Effect Of Substrate Strengthening On Friction And Wear Properties Of Magnetron Sputtered Coatings On Titanium Alloy

Hard coating prepared by magnetron sputtering ion plating has good tribological properties,but the hardness of titanium alloy is low,and it is easy to undergo large plastic odeformation during loading.The mechanical properties between the coating and the substrate are greatly different,the coating is easily cracked under the load,which causes the coating fail to perform its tribological properties,In this paper,surface state of titanium substrate is optimized by the plasma cleaning process parameters.Titanium substrate was strengthened by shot peening and micro-arc oxidation.GLC antifriction and wear-resistant coating and hard CrAlYN coating were prepared by magnetron sputtering ion plating,the effect of titanium substrate strengthening on the tribological behavior of the coating were study.The results show that:The change in surface roughness of titanium substrate caused by plasma cleaning is the main factor affecting the adhesion strength of the coating.As the negative bias voltage of the plasma cleaning increases,the surface roughness of the titanium substrate increases first and then decreases,and the adhesion strength of the coating is positively correlated with it.When the cleaning process parameter is-300V/20min,the surface roughness of the titanium substrate is largest,and the GLC coating has the highest critical load.Surface hardness of shot peening pretreatment TC4 titanium alloy was 412HV0.05,the hardness was increased by 3 1.2%,and the hardened layer has a depth about 180?m.The surface hardness of the micro-arc oxidation pretreatment sample was 746.5HV0.5,and the hardness was increased by about 100%.With the increase of substrate hardness,the surface hardness of the composite treatment samples was higher than the single coating samples..Substrate strengthening improves the coordination of coating and substrate by improving the hardness of substrate,and slow down the cracking and spalling tendency of the coating.After substrate shot peening,the adhesion strength of the coating can be increased by 15.7%,which improves the reliability of the tribological properties.The high hardness of the sample reduces the contact area of the coating,and reduce friction coefficient and wear rate.The friction coefficient of GLC coatings can be reduced by 28%and the wear rate by one order of magnitude after substrate shot peening pretreatment.The friction coefficient of GLC coatings after substrate micro-arc oxidation pretreatment is reduced by 24%.When the applied load exceeds the load bearing capacity of the composite treatment sample,the substrate strengthening effect is invalid,and there is no difference in the tribological properties between the composite treatment sample and the single coating sample.After substrate shot peening pretreatment,the friction coefficient of CrAlYN coating decreases by 9.5%at 2N and the same at 8N.The tribological behavior of coating are also related to the mechanical properties difference between substrate and coating.When the substrate strength is the same,the smaller the difference of hardness and elastic modulus between the substrate and the coating,the better deformation coordination and tribological properties.