真空封孔对高速电弧喷涂涂层耐腐蚀性能的影响

Effect of Vacuum Sealing on Corrosion Resistance of High Speed Arc Spraying Coating

本文通过高速电弧喷涂技术制备NiCr基涂层,采用真空法和直接刷涂法进行封孔处理,对比研究两种封孔工艺对涂层耐腐蚀性能的影响。采用光学显微镜观察涂层的截面微观形貌并计算其孔隙率,采用扫描电镜和能谱仪检测封孔剂的浸渗深度,通过电化学及盐雾腐蚀试验评估封孔后涂层的耐腐蚀性能。结果表明,真空封孔下涂层内封孔剂平均渗透深度为275μm,较直接刷涂法(平均渗透深度为103μm)提高近3倍。真空封孔涂层的腐蚀电流密度比直接刷涂封孔涂层更小,钝化区更为明显。在盐雾腐蚀环境下,432 h后无锈迹出现,而直接刷涂封孔涂层在96 h后产生锈蚀点,表明采用真空封孔技术制备的涂层具有更好的耐腐蚀性能,为真空封孔技术在工程应用提供试验依据。

In this paper,NiCr based coating was prepared by high-speed arc spraying technology and the hole sealing treatment was carried out by Vacuum Impregnation Sealing(VIS)and Conventional Impregnation Sealing(CIS).The effects of the two hole sealing processes on the corrosion resistance of the coating were compared and studied.The cross-section morphology of the coating was observed by OM and its porosity was calculated.The penetration depth of the sealing reagent was detected by SEM and EDS.The corrosion resistance of the coating after sealing was evaluated by electrochemical and salt spray corrosion tests.The results showed that the average penetration depth of sealing reagent in the coating under VIS is 275μm,and was nearly 3 times higher than that of CIS coating(103μm).The corrosion current density of VIS coating was smaller than that of CIS coating,and the passivation area is more obvious.Thus,there was no rust appearing after 432 h under the salt spray corrosion environment.However,the CIS coating produced corrosion points after 96 h.It was indicated that the coating prepared by VIS has better corrosion resistance,which provides an experimental basis for the application of VIS in engineering.