热喷涂Fe基非晶涂层耐腐蚀性与孔隙率研究进展

Porosity and Corrosion Resistance of Fe-based Amorphous Coatings Prepared by Thermal Spraying

热喷涂Fe基非晶合金涂层的综合性能优异,特别是在耐磨、耐腐蚀方面具有传统晶体材料无可比拟的优势,因而广泛应用于材料表面的防护领域。然而热喷涂涂层为典型的层状结构,涂层内部会存在一定量的孔隙,致使涂层耐腐蚀性能下降。首先介绍了热喷涂Fe基非晶涂层的腐蚀机理及其影响因素,总结了热喷涂涂层孔隙产生的机制、分类和影响因素。接着重点介绍了孔隙与热喷涂Fe基非晶涂层耐腐蚀性之间关系的研究进展。最后,通过对热喷涂涂层的形成过程与孔隙形成机理进行分析,粒子铺展变形能力差是显著影响涂层形成时粒子相互嵌套叠加和变形能力的主要原因。所以,Fe基非晶涂层可以从改变喷涂粉末成分和粒度、第二项粒子加入及喷涂工艺参数优化等措施,来改善粒子铺展变形能力,提高致密度。采用激光快速表面重熔技术对涂层微表层进行快速重熔处理,同样可以达到降低涂层孔隙率、提高涂层耐腐蚀性的目的。

Owing to excellent comprehensive performance, especially incomparable advantage in wear and corrosion resistance compared with traditional crystalline materials, thermal sprayed Fe-based amorphous coating is widely used for surface protection. However, as a typical lamellar structure, it has certain amount of pores inside as well, resulting in reduction of its corrosion resistance. Corrosion mechanism of Fe-based amorphous coating and factors influencing its corrosion resistance were first introduced, forming mechanism, classification and influencing factors of thermal sprayed Fe-based amorphous coating were summarized. Then research progress of relationship between pore defects and corrosion resistance of Fe-based amorphous coating was introduced in details. According to analysis of thermal sprayed coating formation process and pore formation mechanism, poor spreading and deformation capabilities of particles had significant effects on mutual embedding and deformability of particles when the coating took shape. Therefore, Fe-based amorphous coating could improve the spreading and deformation capabilities of particles and even compactness of the coating by changing composition of spraying powder, particle size, adding second-phase particle and optimizing spraying process parameters. Remelting the coating microlayer rapidly by adopting laser rapid surface re-melting technology could also reduce the porosity and improve corrosion resistance of the coating.