中文摘要：

采用压片预置式激光多层熔覆制备了厚纳米Al2O3-13%TiO2（质量分数）涂层,研究了涂层的微观组织和结合性能,并分析了涂层厚度对结合强度的影响。结果表明,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,并且涂层中的裂纹基本集中于部分熔化区,另外晶粒尺寸表现为上小下大的梯度过渡特征。随着涂层厚度的增加,结合强度逐渐下降,其减小的趋势为先快后慢。厚度为175μm的试样结合强度高于78.6 MPa,而厚度为350、525、700μm的涂层结合强度分别为66.3、47.4、36.2MPa。

英文摘要：

The thick nanostructured Al2O3-13%TiO2（mass fraction） ceramic coating is prepared by squash presetting type laser multi-layer cladding.The microstructure and bonding strength of coating are investigated,and the effect of coating thickness on bonding strength is analyzed.The results show that the laser-clad ceramic coating has no obvious interface between the layers but dense,continuous structure,and there is almost no pore and large penetrating crack.The coating is composed of fully melted regions（fine equiaxed grains） and partially melted regions（remained nanoparticles）.In addition,most cracks in the coating are concentrated on the partially melted region.Due to multiple heating by laser beam,the grain size of lower layer is bigger than that of upper layer.The bonding strength of coating decreases with the increase of coating thickness,and the trend is fast at first and then slow.The bonding strength of coating with a thickness of 175 μm is beyond 78.6 MPa,while those of 350,525,700 μm thickness coatings are 66.3,47.4,36.2 MPa,respectively.