Study Of Effect Of PEMS Process Parameters On Tribological Behavior Of CrN/Al Friction Couples

In the aluminum extrusion process,the extrusion die is easy to adhere with aluminum,which causes serious wear and severely affects the service life of the mold.CrN coating has high hardness,high wear resistance and other properties,and is widely used to improve the wear resistance and life of aluminum alloy extrusion die.Plasma Enhanced Magnetron Sputtering?PEMS?can significantly improve the structure and properties of the coating,but the effect of process parameters on the tribological properties of CrN/Al is still unclear.In this paper,different CrN coatings were prepared on the surface of H13 steel by changing the PEMS process parameters.The effect of process parameters on the tribological behavior of PEMS-CrN/Al was studied.The conclusions are as follows:?1?With the increase of bias current,the structure of CrN coating is changed from loose to dense,and the surface of CrN coating which prepared at 0.1 A and 1.5 A bias has obvious texture structure.With the increase of bias flow,the phase structure of CrN coating is increased.The Cr?N?phase transforms into the Cr₂N phase and the Cr?N?phase eventually transforms into a pure Cr₂N phase.The hardness H,modulus of elasticity E,H/E*,H³/E*² of the CrN coating exhibited a pattern of first increase and then almost no change with increasing bias current.With the increasing of the bias current,the friction coefficient showed a trend of increasing first and then decreasing and then increasing.The wear rate of CrN coating samples showed a trend of decreasing first and then increasing.The percentage of aluminum adhered area of CrN coating sample surface was increased.The trend of first decrease and then increase slightly decreases.When the bias current is 1.5 A,the surface of CrN coating specimen has the slightest aluminum adhesion and the best wear resistance.?2?With the increasing of nitrogen flow rate,there is no effect on the density of CrN coating,and the nitrogen content of CrN coating increases gradually.With the increasing of nitrogen flow rate,the phase structure of CrN coating changes from Cr?N?phase to Cr₂N phase and Cr?N?phase to pure Cr₂N phase and finally Cr₂N phase and CrN phase.The hardness H,modulus of elasticity E,H/E*,H³/E*² of the CrN coating exhibited the law of increasing first and then decreasing with the increase of the nitrogen flow rate.In the initial stage of friction and wear,the friction coefficient will increase first and then decrease with the increasing of nitrogen content.However,with the friction and wear tests carried out,the friction coefficient tends to be stable,and the wear rate of the coating first decreases.Trend towards stability.In the adhesion of aluminum,the increasing of the nitrogen flow rate has no significant effect on the aluminum-adhesion resistance of the coating.However,due to the poor mechanical properties of the CrN coating prepared when the nitrogen flow rate is 15 sccm and the nitrogen flow rate is 40sccm,the aluminum on the coating surface will fall off along with the coating during friction and wear test,resulting in the entire wear scar.The adhesion of aluminum on the surface of the coating increases first and then decreases with increasing nitrogen flow.