Manufacturing Of Ceramic/Metal Coating On Copper Substrate And Research On Microstructure And Performance

Tuyere which is an important part of the blast furnace is often destructed by the formidable working conditions,such as abrasion form coal dust with high rate and erosion from burner gas with high temperature.At the present,domestic tuyeres are made of pure copper,and their lives are only 2～3 months.If tuyeres are changed frequently,the stability of the blast will be cost;the production of the blast will be reduced;the working strength of workers will be increased.Studying the means of improving the service life of tuyere is actual significance.In this paper,base on the application of tuyere,the thermal barrier coating(TBC) were designed,and the double-layer structure thermal barrier coating of nano-ceramics(ZrO₂-8% Y₂O₃)-bonding layer(NiCrAIY)-matrix(Cu) and micro-ceramic(ZrO₂-8%Y₂O₃)·bonding layer(NiCrAIY)-matrix(Cu) were prepared by atmospheric plasma spraying (APS) and high velocity oxy-fuel(HVOF);the micro-morphology of the prepared coating was observed;the tensile test,thermal shock test,insulation performance analysis and thermal stress simulation of the prepared coating were carried out.The results showed that:compared with the traditional ceramic coating,the microcracks and pores of the nano-ceramic coating are smaller,which is conducive to improve the insulation effect of the coating.When the temperature field reaches steady state,the maximum temperature and the lowest temperature of pure copper tuyere are 332℃and 34℃;the maximum temperature and the lowest temperature of double layered coating tuyere are 364℃and 39℃;the maximum temperature and the lowest temperature of double layered coating tuyere with incrustation scale are 656℃and 39℃,the surface maximum temperature of coating and substrate of double-layer coating tuyere is 332℃and the surface maximum temperature of coating and substrate of double layered coating tuyere with incrustation scale is 588℃.The thermal conductivity of ceramic layer the smaller the insulation effect the better,however,in a small area the effect of changes in its influence is very limited.The convection coefficient of copper border the greater maximum temperature the lower and insulation effect of TBC the better.The coating side of the interface of single-layer coating and double coating,the maximum stress that perpendicular to the interface is respectively 195MPa and 58.2MPa,the maximum stress that parallel to the interface is respectively 79MPa and 40.9MPa.Mechanical is the main combination ways of coating,bonding layer and the substrate interface is in most of the weak throughout the coating-substrate system;with plasma spraying the bonding layer as compared to the use of HVOF to prepare bonding layer can effectively improve the bond strength of ZrO₂ coating on copper substrate,that can improve the bonding strength of 54%.The thermal shock performance of nano-ceramics(ZrO₂-8%Y₂O₃ + NiCrAlY) coating is better than the thermal shock performance of the traditional micro-ceramic coating;the thermal shock performance of coating whose bonding layer is prepared by HVOF is better than the thermal shock performance of coating whose bonding layer is prepared by plasma spay.