厚度对车用304不锈钢表面激光熔覆钛涂层组织性能的影响

Effect of Thickness on Microstructure and Properties of Laser Cladding Titanium Coating on Automotive 304 Stainless Steel

运用激光熔覆工艺在304不锈钢表面制得钛涂层,并对其组织结构、厚度、物相成分进行了表征。研究结果表明:厚度0.5 mm涂层表面生成的放电孔洞边缘出现了许多熔融物,还有部分放电孔洞中生成了新的熔融物,导致有些区域只形成了少量孔洞,并呈现不规则外形。此时涂层内部形成了致密结构。熔覆时间到达5 min时,厚度0.5 mm涂层电压发生了快速升高,涂层持续发生击穿放电过程并保持恒定速率增加,到达8 min左右时,电压增长速率保持缓慢上升。采用激光熔覆方法将电解液中的P、Ca元素引入涂层内,各个厚度涂层表面均存在一定数量的Fe元素。厚度0.1 mm涂层的表面存在NiTi与部分Ti以及不同晶型的TiO2;厚度0.5 mm涂层内NiTi衍射峰强度发生了明显降低,而Ti含量显著升高,形成了更强的TiO2衍射峰。

The titanium coating was prepared on 304 stainless steel by laser cladding technology,and its structure,thickness and phase composition were characterized.The results show that there are many molten materials on the edge of the discharge holes generated on the surface of the coating with a thickness of 0.5 mm,and some new molten materials are generated in the discharge holes,resulting in only a few holes in some areas and irregular shape.At this time the coating internal formation of a dense structure.Upon reaching 5 min,the coating voltage with a thickness of 0.5 mm increased rapidly,and the coating continued the breakdown discharge process and maintained a constant rate of increase.Upon reaching about 8 min,the voltage growth rate maintained a slow rise.The P and Ca elements in the electrolyte were introduced into the coating by laser cladding method.There are NiTi and some Ti and different crystalline TiO2 on the surface of the coating with a thickness of 0.1 mm.The intensity of NiTi diffraction peak in the coating with a thickness of 0.5 mm was significantly reduced,while the content of Ti was significantly increased,forming a stronger TiO2 diffraction peak.