Study On Laser Cladding Of Core-shell Zirconium Tungstate Reinforced Invar Alloy Composite Coating

In this work,Invar alloy is selected as the matrix,SiC ceramic particle phase is introduced to improve the wear resistance of the coating,and the negative thermal expansion material ZrW₂O₈ is added.The expansion behavior and residual stress of the coating improve the safety and reliability of the coating.In this paper,ZrW₂O₈ was coated with a high temperature resistant oxide to form a core-shell structure.The core-shell type zirconium tungstate-SiC-Invar alloy composite coating was prepared by laser cladding technology.Scanning electron microscopy?SEM?,X-ray diffractometry?XRD?,infrared spectrometer?FTIR?,transmission electron microscopy?TEM?and friction and wear tester were used to analyze the microstructure,phase composition and mechanical properties of the coating.The main findings are as follows:The results show that the coating effect of physical precipitation method is poor,and the coating layer is not dense;the core-shell type ZrW₂O₈ prepared by tetrabutyl titanate and zirconium n-butoxide has good coating effect and dense coating layer.As the amount of distilled water gradually increases,the thickness of the coating gradually becomes thicker;as the content of zirconium n-butoxide increases,the thickness of the coating increases.When the laser cladding is invar coating,the surface of the single-pass single-layer coating is good,and there is no crack inside the coating,and there is no hole.With the increase of SiC content,the surface of the coating is smooth and smooth.When the SiC content is 4%,The surface quality of the coating is the best.With the increase of SiC content,the hardness of the coating gradually increases.When the SiC content is 4%,the friction coefficient of the coating is the largest,and the maximum is 0.7.As the lap joint increases,the hardness stabilizes at 150 HV.At a lap ratio of 45%,the coating is the most flat and there is no crack inside the coating.After adding the core-shell type ZrO₂-ZrW₂O₈ powder,the surface of the cladding layer has less pores,the coating is flatter and the hardness is higher.With the increase of ZrO₂-ZrW₂O₈ content,the hardness of the coating increases gradually.When the content is12%,the hardness of the coating is the highest,reaching 550HV,which is 3.8 times that of Invar.As the thickness of the coating increases,the friction coefficient of the coating remains stable at around 0.4,and the wear resistance is gradually improved.