Study On Laser Cladding Cr₃C₂-NiCr And Cr₃C₂-NiCr+Ni60 Wear-resistant Coating On Mould CuCrZr Alloy

The Cr₃C₂-NiCr and Cr₃C₂-NiCr+Ni60 cladding layer mixed with different rates were prepared to the surface of crystallizer CuCrZr alloy by the method of laser cladding.Taking the average cross-section microhardness of cladding layer as index,the process parameters of Cr₃C₂-NiCr and Cr₃C₂-NiCr+Ni60 cladding layer optimized through orthogonal test method was used to prepare multichannel Cr₃C₂-NiCr and Cr₃C₂-NiCr+Ni60 cladding layers.The thermal shock resistance and antifriction property of prepared sample was investigated through the thermal shock test and friction and wear test.Among the selected process parameters,the results showed:For Cr₃C₂-NiCr cladding layer,the major and minor relationship of the effect of parameters on microhardness was: firstly cladding speed,then laser power and finally the rate of power feeding.The average cross-section microhardness of the cladding layer was 978.5HV.Also,for the Cr₃C₂-NiCr and Ni60 cladding layer mixed with different rate,and the major and minor relationship of the effect of parameters on microhardness was: firstly laser power,then cladding speed and finally the rate of power feeding.The cross-section average microhardness cladding layer obtained by optimized parameters was 930.4HV with the 90% Cr₃C₂-NiCr,886.3HV with the 80% Cr₃C₂-NiCr and 842 HV with the 70% Cr₃C₂-NiCr.As the rate of Ni60 powder increased,the average microhardness decreased slightly,but the macrostructure of cladding layer was improved apparently.The thermal shock property of Cr₃C₂-NiCr and Cr₃C₂-NiCr+Ni60 cladding layer mixed with different rates was equal to that of the plasma sprayed coating,thermal shock with 500 times was not failure at 450?.And when the temperature was 750?,the thermal shock property of Cr₃C₂-NiCr and Cr₃C₂-NiCr+Ni60 cladding layer mixed with different rates was better than that of the plasma sprayed coating.What's more,when mixing with Ni60 powder,the thermal shock property was increased obviously,and with the amount of Ni60 powder increasing,the thermal shock property was improved.The antifriction property of laser cladding CuCrZr to crystallizer was improved apparently,which was about 2.7².9 times of that.After mixing with certain Ni60,the antifriction property was further increased,which was about 3.2³.4 times of that.The metallurgical reaction of the interface of single Cr₃C₂-NiCr cladding layer and substrate was not obvious.After mixing with Ni60 powder,the diffusion of Cu element and Ni element at the interface between the cladding layer and the substrate was obvious,which reached the better metallurgical bonding and improved the bonding strength.And at the same time,the difference of linear expansion coefficient between cladding layer and substrate was decreased and the thermal shock property was improved.During the wear process,on the premise of ensuring the hardness of cladding layer,the Cu element diffused to cladding layer,and the oxidized Cu played the role of lubrication which improve the antifriction property.