激光多层熔覆制备厚陶瓷涂层

研究了压片预置式激光多层熔覆纳米团聚体Al2O3-13%TiO2粉末制备厚陶瓷涂层,试验中通过保温箱对试样进行预热和缓冷处理、引入超声振动及对熔池温度闭环控制等措施来控制熔覆层的裂纹.结果表明,厚陶瓷涂层各层之间无明显界面,过渡缓和自然,涂层内部致密、连续、基本无孔隙及贯穿性大裂纹等缺陷;涂层由等轴晶的完全熔化区和残留纳米颗粒的部分熔化区组成,而且涂层中的裂纹基本集中于部分熔化区;另外由于经历激光的多次加热,下部区域的晶粒组织要大于上部区域,而由于保温箱的缘故,整个涂层晶粒偏大.

Experimental on preparation of thick ceramic coating by laser multi-layer cladding

The preparation of thick ceramic coating by squash presetting type laser multi-layer cladding with Al2O3-13%TiO2 nanostructured agglomerated powders was studied.The crack of clad layer was controlled by preheating and slow cooling rate of sample with incubator,applying the ultrasonic vibration and closed-loop controlling temperature of molten pool during laser cladding process.The results show that the laser-clad thick ceramic coating has no obvious interface between the layers with dense,continuous structure,and almost no pores and large penetrating cracks.The coating is composed of fully melted zones(fine equiaxed grains) and partially melted zones(remained nanoparticles).In addition,the most cracks in the coating are present in the partially melted zone.Due to multiple heating by laser beam,the grain size of lower layer is bigger than that of upper layer,and the grain size of total coating is large because of the use of incubator.