AH32钢表面等离子喷涂制备疏水涂层及其耐腐蚀性能研究

目的提高AH32海洋用钢表面的疏水性及耐蚀性,并给出最佳性能的喷涂涂层成分。方法采用大气等离子喷涂技术,在AH32钢表面制备了三种不同成分的涂层。利用微量进样器结合半球法测量了涂层的接触角,并利用Qwen-Wendt公式对涂层的表面能进行了计算,利用扫描电子显微镜观察涂层的表面形貌,利用表面粗糙度仪测量涂层的表面粗糙度,利用冲刷实验及电化学工作站测量了不同涂层的耐蚀性能,并讨论了不同涂层的疏水机制及相应的腐蚀机理。结果等离子喷涂涂层显著改善了AH32钢的疏水性能。相比而言,等离子喷涂Co基涂层及等离子喷涂Ni基涂层与水的静态接触角达到了130°以上,均具有较好的疏水效果。三种涂层均明显改善了AH32钢的耐海水冲刷腐蚀能力,其中AH32钢基体腐蚀30d后的失重为1.68×10^-2 g/cm²,等离子喷涂Ni基涂层的腐蚀失重最小,约为4.2×10^-3 g/cm²。极化曲线测试结果也表明,三种涂层的自腐蚀电位较基体提高了300 mV左右,并且腐蚀电流密度较基体降低了1个数量级以上,另外Co基涂层的腐蚀电流...

Study on Corrosion Resistance of Hydrophobic Coating Prepared on AH32 Steel by Plasma Spraying

The work aims to improve the hydrophobic and corrosion resistance of AH32 marine steel and give the excellent composition of the coating with the best performance. Atmospheric plasma spraying was used to prepare three kinds of coatings with different compositions on the surface of AH32 steel. The contact angles of the coatings were measured by microsyringe with the method of hemisphere. The surface energy of the coatings were calculated using the Qwen-Wendt formula. The surface morphologies of the coatings were observed by the scanning electron microscope. The surface roughnesses of the coatings were measured by surface roughness meter. The corrosion resistances of different coatings were measured by the electrochemical workstation. The corresponding mechanisms of hydrophobic and corrosion of different coatings were also discussed. The results show that the hydrophobic properties of AH32 steel with coatings prepared by plasma spraying were improved significantly. In contrast, the static contact angle of Co-based coating and Ni-based coating with water were more than 130° and both coatings have excellent hydrophobic effect. Moreover, the seawater erosion resistances of AH32 steel with three coatings were improved significantly. The corrosion weight loss of AH32 steel substrate is about 1.68×10-2 g/cm2, and the corrosion weight loss of the Ni-based coating is the smallest, about 4.2×10-3 g/cm2. The polarization curve test results also show that the self-corrosion potential of the three coatings is about 300 mV higher than the substrate, and the corrosion current density is more than one order of magnitude lower than that of the substrate. In addition, the corrosion current density of the Co-based coating is higher than that of the Ni-based coating. Hydroxyl groups produced by Co-based coating corrosion process lead to the decrease of the static contact angle between Co-based coating and water and hydrophobic performance degradation of Co-based coating. Therefore, the plasma spraying Ni-based coating has the excellent hydrophobic, the smallest corrosion rate and the excellent erosion-corrosion resistance. Compared with that of the matrix, the corrosion weight loss of the plasma spraying Ni-based coating was reduced by 1.26×10-2 g/cm2.