Preparation And Performance Evaluation Of Wear Resistance And Corrosion Resistance Coatings On The Surface Of Injection Molding Machine Screw

The Ni35,Fe base,Co base and Ni60 A alloy cladding layers were prepared by laser cladding on the surface of 38 CrMoAl steel,Ti-N coating and GLC coating were prepared by magnetron sputtering,nitrided layer was prepared by ion nitriding.The effects of rare earth CeO₂ content on the microstructure,wear resistance and corrosion resistance of Ni60 A laser cladding layers were researched.The wear resistance and corrosion resistance of different coatings were characterized and evaluated.The results showed that:（1）The Ni35,Fe base,Co base and Ni60 A alloy powers are coated on38 CrMoAl steel.The laser cladding layers thickness are about 1mm or so.All these four cladding layers have fine dendrites,the dendrites of Ni60 A cladding layer are the finist.The Ni60 A cladding layer has the highest surface microhardness（771HV0.1）and the best wear resistance,which wear rate is1.52×10^-14m³/N.m.Fe based cladding layer,Co based cladding layer,Ni35 cladding layer wear resistance successively reduce.The Ni60 A and Co base cladding layer have the best corrosion resistance and the corrosion resistance protection rating are both 8.（2）The addition of rare earth CeO₂ plays a role in refining and purification the organization of Ni60 A cladding layer,it also can promote the formation of short rod carbide M₂₃C₆（M=Fe,Ni,Cr）.With the increase of rare earth CeO₂ content,the microhardness,wear resistance and corrosion resistance of the cladding layer increase first and then decrease.When the addition amount of rare earth is 1%,the surface hardness reaches the highest（731.87HV0.1）,which is 31.34% higher than the cladding layer without rare earth,the wear resistance is the best and the wear rate is 3.057×10^-14 m³/N.m,compare with no rare earth cladding layer increase by 335%.When the addition amount of rare earth are0.5% and 1%,the cladding layers have the best corrosion resistance and the corrosion protection rating are both 5.（3）The wear resistance of GLC coating is the best,the wear rate is2.91×10^-16m³/N.m,which twice orders of magnitude lower than the other coatings.Ti-N coating,Ni60A+1%CeO₂ cladding layer,Nitrided layer wear resistance successively reduce.The corrosion resistance protection rating decreases in order of Ni60A+1%CeO₂ cladding layer（RP=8）,GLC coating（RP=3）,Ti-N coating（RP=2）and Nitrided layer（RP=2）.（4）The GLC coating is suitable for wear resistance injection moldingmachine screw.The Ni60A+1%CeO₂ cladding layer is suitable for corrosion resistance injection molding machine screw.