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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。
The thick nano-Al2O3-13% TiO2 (mass fraction) coating was prepared by using the laser pre-laser cladding method. The microstructure and bonding properties of the coating were studied. The influence of coating thickness on the bonding strength was also studied. The results show that there is no obvious interfacial transition between the ceramic coatings, natural transition, the dense, continuous, almost non-porous and penetrating large cracks in the coating. The coating consists of a completely melted zone of equiaxed grains and residual nanoparticles , And the cracks in the coating are mainly concentrated in the partially melted zone. In addition, the grain size shows the characteristics of gradient transition from small to large. With the increase of coating thickness, the bonding strength gradually decreases, and the decreasing trend of the bonding speed is slowing first and then slowly. The bond strength of the sample with the thickness of 175 μm was higher than 78.6 MPa, while the bond strengths of the coatings with the thickness of 350, 525 and 700 μm were 66.3, 47.4 and 36.2 MPa, respectively.