Al基金属玻璃涂层孔隙特性的精确表征及对其腐蚀行为的影响规律

Accurate Characterization for Pore Properties of Aluminum-based Metallic Class Coating and the Influence of Pores on Corrosion Behavior of Coating

选用Al86Ni6Y4.5Co2La1.5铝基非晶粉体材料,采用自研的低温超音速喷涂系统,在ZM5表面制备了具备良好耐蚀性能的铝基金属玻璃涂层,分析了涂层的孔隙类型及成因,优选出X射线三维成像法测定了涂层孔隙率,表征了涂层孔隙几何特征,阐明了孔隙对涂层腐蚀行为的影响规律。结果表明,涂层主要包含宏观型、层间型、微球型和微细型四类常规孔隙缺陷;涂层孔隙率基本小于1%且沿厚度方向上变化不大,孔隙呈近球形,尺寸均小于10μm,尤以5μm左右居多;不同孔隙率的涂层均呈现出较宽的自钝化区间,自腐蚀电位较为接近,腐蚀电流密度与孔隙率正相关,大尺寸、贯穿型、边界处的个别特殊孔隙是导致涂层腐蚀失效的根本原因。

The aluminum-based metallic glass coating on ZM5 surface with good corrosion resistance was prepared from Al86Ni6Y4.5Co2La1.5 amorphous powder by self-developed low-temperature supersonic spray system.The types and causes of pores in the coating were analyzed,the porosity of the coating was determined by X-ray three-dimensional imaging method,the pore geometry features were characterized,and the influence of pores on the corrosion behavior of the coating was clarified.The results show that the coating consists mainly of four types of conventional porosity defects,which are macro-type,layer-type,microsphere-type and microscopic-type.The porosities are substantially less than 1% and have little change along the thickness direction.The pores are nearly spherical,and their average sizes are less than 10 μm,mostly about 5 μm;the coatings of different porosities show a wide range of self passivation interval,self corrosion potentials are closer,and there is a positive correlation between the corrosion current densities and porosities.Individual special pores at the border with the characteristics of large-size and through-type are the fundamental cause of corrosion failure of the coating.