Study On Preparation And Properties Of Wear Resistant Coating For Copper Plate Of Mold

The mould is the core device in the continuous casting production process.As an important part of the mould,the working conditions of the mould copper plate are very poor,and it is easy to breakdown,which affects the production efficiency of continuous casting.Therefore,it is very important to take surface strengthening on copper plate in mould.In this paper,Ni-based spraying coatings were prepared on copper plate by HVOF at frist,and studied the effect of vacuum high temperature diffusion on the structure and properties of sprayed coatings.Meanwhile the wear-resistant composite coating of mould copper was prepared by laser cladding,with pure copper as matrix and the powder of Ni60 and 20%TiC as cladding materials.And studied the effects of ZrO2 and AIN content on the toughness and thermal conductivity of the coatings.And the structure and properties of the coatings were characterized by SEM,XRD,EDS,three-dimensional topography,multi-functional friction and wear tester and laser thermal conductivity tester.The results show that:vacuum high temperature diffusion can obviously eliminate the inherent defects of sprayed coatings,reduce the crack and pore defects in coatings,homogenize the structure of coatings,and improve the wear resistance and thermal conductivity of coatings.It is found that the effect of high temperature diffusion on the coating is most obvious when the diffusion temperature is 1020 C.If the diffusion temperature too high,it will make the grain size of the coating coarser and reduce the wear resistance.The addition of ZrO₂ can change the distribution of TiC in the coating from bulk particles to dendrites and short rods,and repair micro-cracks in the coating,and improve the micro-hardness and wear resistance of the coating.Through comparison,it can be found that when the content of ZrO2 is 1%,the effect of improving the coating is most obvious,the hardness of the coating is the highest,and the wear resistance is the best.But when the content of ZrO 2 is too high,the uniformity of the coating structure will be reduced and the performance will be reduced.After adding AIN into the cladding material,it can be found that the grain size of the coating is refined and the uniformity of the structure is improved.AIN is decomposed in the cladding process,and A1 element is combined with Ni and Ti in the coating.The intermetallic compound improves the adhesion between the coating matrix and TiC particles,so the micro-hardness and wear resistance of the coating are improved.It can be found that when the content of AIN was 10%,the hardness and wear resistance of the coating were the highest.When the content of AIN is too high,the intermetallic compounds with higher brittleness in the coating increase,which results in the decrease of wear resistance.Because of the good thermal conductivity of AIN,the thermal conductivity of the coating was improved obviously after adding AIN.