Preparation Of Modified Aluminum Silicon-siloxane Composite Sealing Layer And Study On Its Wear And Corrosion Resistance

In this paper,Ce（NO₃）₃ modified aluminum silicon-silicone composite sealing agent was prepared by sol-gel method.The composition,structure and heat resistance of the sealing agent were studied.The sealing layer was prepared on the supersonic flame sprayed Cr₃C₂-NiCr coating by brushing method.The microstructure of the coating before and after sealing was analyzed.The effect of sealing agent on the corrosion resistance,friction and wear and tribocorrosion properties of the coating was studied.The mechanism of the sealing agent in the friction and wear and tribocorrosion of the coating is revealed.The research work has yielded some valuable results and laid the foundation for its industrial application.The main findings are as follows:（1）Aluminum-silicon composite sealing agent with different content of MTMS（Methyltrimethoxysilane）was prepared.The effect of MTMS content on the heat resistance of the sealing agent and the corrosion resistance of the sealing coating was investigated.The results show that the prepared composite sol powder mainly contains SiO₂ and a small amount of Al₂O₃,and the heat-resistant temperature of the sealing agent increases with the decrease of MTMS content.The heat-sealing temperature of the sealing agent at 30 wt.%MTMS is as high as 230°C.The surface of the sealed Cr₃C₂-NiCr coating is smooth and flat,and its corrosion resistance is significantly improved.When the MTMS content is 40 wt.%,the coating has the best corrosion resistance.（2）The Ce（NO₃）₃ modified MTMS aluminum-silicon composite sealing agent was prepared.The influence of Ce（NO₃）₃ on the heat resistance of the sealing agent and the corrosion resistance of the sealing coating was investigated.The results show that the addition of Ce（NO₃）₃ can improve the heat resistance of the sealing agent to some extent.The corrosion resistance of the sealing coating increases first and then decreases with the increase of Ce（NO₃）₃ content.When the content of Ce（NO₃）₃ is 1.0wt.%,the coating has the best corrosion resistance.This may be due to the formation of CeO₂ protective film by Ce（NO₃）₃ under corrosive medium,which enhances the corrosion inhibition effect of the sealing agent.（3）The high temperature friction and wear and tribocorrosion properties of the coating before and after sealing were studied,and the wear and corrosion resistance mechanism of the sealing agent was explored.The results show that when the Ce（NO₃）₃ content is 1.0 wt.%,the friction load has a great influence on the wear resistance of the coating.As the load increases,the antifriction effect of the sealing agent becomes weak.This is mainly due to the fact that the sealant particles cannot be filled into the interior of the coating in time when the load is increased,and the wear of the coating can only be aggravated as abrasive particles.When the content of Ce（NO₃）₃ in the sealing agent is in the range of 0¹.5 wt.%,the friction coefficient and wear rate of the coating after sealing at high temperature are gradually decreased with the increase of Ce（NO₃）₃ content.Similarly,Tribocorrosion performance is gradually weakened.