Preparation And Properties Of Corona Roll Coating For New Energy Vehicle Tape Casting Equipment

In the field of new energy vehicles,thin films are widely used,such as thin film capacitors,exterior panels,and thin films for power batteries.Thin films are important materials for new energy vehicle components.These thin films are produced by casting equipment.Corona rollers are key components of casting equipment and have been used in high-voltage electric fields for a long time.Traditional corona rollers are lined with rubber and polymer resins such as silicone rubber,butane rubber,epoxy resin,etc.on the metal roller body to obtain insulation.However,these lining materials are prone to aging,wear,and deterioration,which affects their lifespan.In order to improve its electrical insulation,arc resistance,abrasion resistance and chemical stability,atmospheric plasma spraying technology is often used to solve these problems by spraying coatings on the corona roll surface instead of rubber resin surface.Alumina（Al₂O₃）coating has good insulation,mechanical properties and other characteristics,is widely used as insulation coating,because of its brittleness,a single material has its own defects,need to introduce good insulation,wear resistance,thermal conductivity of hexagonal boron nitride（hBN）fill modification.At present,there are few systematic studies on the properties and preparation process of Al₂O₃-hBN composite coatings,and the relationship between spraying process parameters,micromorphology and performance has not been established.Therefore,in this study,Al₂O₃and hBN were proportionally 97:3.Mechanical mixing into Al₂O₃-hBN composite material,Al₂O₃-hBN composite coating as the research object,to carry out spraying process parameter optimization experiments,using scanning electron microscopy（SEM）and X-ray diffractometry（XRD）to analyze the coating microstructure phase composition,respectively.And explore the effects of process parameters on the porosity,microhardness,bonding strength,insulation properties and wear resistance of composite coating,and finally determine the optimal spraying parameters.The main research content and conclusions are as follows:1.Using pure Al₂O₃ powder as raw material,the Al₂O₃coating was prepared on the surface of 20 steel matrix by atmospheric plasma spraying technology.The Al₂O₃coating is mainly composed of metastable phaseγ-Al₂O₃and a small part of stable phaseα-Al₂O₃.The layered structure results in high density.It provides a control for the optimization experiment of Al₂O₃-hBN composite coating.2.Using Al₂O₃-hBN composite powder as spraying material,9 groups of composite coating samples were prepared by orthogonal experimental design to optimize spraying current,H₂flow rate and spraying velocity.The composite coatings are composed of complete melting zone,partial melting zone,microcracks and holes.The phase composition is mainlyγ-Al₂O₃,a small amount ofα-Al₂O₃,and a low content of hBN phase.3.By using the Grey Relational Analysis method based on orthogonal experimental design,a comprehensive analysis of five performance parameters was conducted,and the correlation coefficient and degree were calculated.The response situation of grey correlation analysis was established.The optimized combination scheme for Al₂O₃-hBN composite coating parameters was A3B1C3（numbered 10#）,with spraying current of 650A,H₂flow rate of 8L/min,and spraying speed of 1000mm/s.According to this optimization scheme,10#composite coating was prepared.The results showed that the porosity of Al₂O₃-hBN composite coating optimized by grey correlation method was reduced by 44%,microhardness was increased by 25.6%,bonding strength was increased by 12.6%,insulation performance was reduced by 37.5%,and wear resistance was improved by 35.2%compared to pure Al₂O₃coating.Except for the insulation performance,the other performance is better with composite coatings,which improves the coating quality.4.Using the range method based on orthogonal experimental design,a range analysis was conducted on the five performance results of composite coatings to explore the influence of different spraying process parameters on performance.The optimized combination scheme of Al₂O₃-hBN composite coating parameters was obtained as A3B2C3（numbered 11#）,with a spraying current of 650A,a H2 flow rate of 10L/min,and a spraying speed of 1000mm/s.The 11#composite coating was prepared according to this optimized scheme.The results showed that the Al₂O₃-hBN composite coating optimized by the range method decreased porosity by 5.1%,increased microhardness by2.1%,increased bonding strength by 9.5%,improved insulation performance by 62.2%,and improved wear resistance by 11.5%compared to the composite coating optimized by the grey correlation method.The comprehensive performance of the 11#coating was better than that of the 10#coating and pure Al₂O₃coating prepared by the grey correlation method.By comparison,the optimal combination scheme of the process parameters for preparing Al₂O₃-hBN composite coating is A3B2C3,that is,the spraying current is 650A,the H₂flow is 10L/min and the spraying speed is 1000mm/s.