激光重熔对电弧喷涂含非晶相铁基涂层性能的影响

目的提高电弧喷涂含非晶相Fe基涂层的抗冲蚀及耐腐蚀性能。方法采用YAG脉冲激光器对电弧喷涂含非晶相Fe基涂层进行激光重熔处理。通过X-ray、SEM、冲蚀磨损和电化学等检测手段,研究该涂层重熔后的组织结构、冲蚀磨损性能和耐腐蚀性能。结果电弧喷涂含非晶相Fe基涂层经激光重熔后发生了晶化,并随着功率的增加,非晶含量降低,硬度也降低。重熔后,涂层与基体的结合方式由之前的机械咬合转变为冶金结合,涂层的致密度明显提高,组织缺陷减少。与喷涂层相比,0.3k W激光重熔涂层的抗冲蚀性能在30°攻角下可提高3倍,在90°攻角下可提高将近6倍。重熔层的冲蚀磨损机制在低冲角时以显微切削为主,高冲角时则以挤压破碎为主。随着激光功率的增加,重熔涂层的抗冲蚀性能降低。同时,在3.5%NaCl溶液中,重熔层的耐蚀性能随重熔激光功率的提高而提高,并且重熔层的腐蚀电流密度比喷涂层明显降低。结论激光重熔不但改善了电弧喷涂含非晶相Fe基涂层与基体间的结合状态,同时也增强了涂层的耐蚀和耐磨性能,是一种有效提升涂层性能的后处理工艺。

Effect of Laser Remelting on Slurry Erosion and Corrosion Properties of Arc-sprayed Fe-based Amorphous-containing Coatings

The work aims to improve the slurry erosion wear resistance and corrosion resistance of arc-sprayed Fe-based amorphous-containing coatings. Arc-sprayed Fe-based amorphous-containing coatings were remelted by YAG lasers. The mi-crostructures, slurry erosion wear resistance and corrosion resistance of the remelted coatings were investigated by X-ray, SEM, erosion tester and electrochemical workstation. The arc-sprayed amorphous-containing coating was crystallized after laser re-melting. With the increase of laser power, the amorphous content and the hardness decreased. After laser remelting, the bonding form between the substrate and coating was converted from mechanically occlusion to metallurgical bonding, the density of the remelted coating increased obviously and the structure flaws decreased. Compared with the sprayed coating, the erosion resistance of the 0.3 kW laser remelted coating could be increased by 3 times at 30 degrees of impact angle, and increased by nearly 6 times at 90 degrees of impact angle. The domain mechanism of erosion wear was micro-cutting at low impact angle, while extrusion fractures at high impact angle. However, the erosion resistance of remelted coating decreases with the increase of laser power. At the same time, the corrosion resistance of remelted coating in 3.5% NaCl solution increased as the laser power grew, but the corrosion current density was significantly reduced when compared with that of as-sprayed coating. Laser remelting can not only improve the bonding condition between the substrate and arc-sprayed amorphous amorphous-containing coatings, but also evidently enhance the erosive wear resistance and corrosion resistance at the same time. Therefore, laser remelting is an efficient post treatment process to improve the properties of coatings.