架空导线表面发黑原因及其钝化处理效果

Surface Blackening Analysis and Passivation Process of Overhead Conductors

近年来国内外架空导线在长期运输和存储过程中,导线最外层铝线表面在富含氯离子、硫离子的工业大气和高温高湿双重作用下常出现不均匀性黑膜现象。采用扫描电镜和能谱仪分析了发黑导线的微观形貌和微区成分,并研究了导线的表面无铬钝化处理工艺。研究发现:导线氧化发黑过程与其通电运行数月后的氧化过程一致,是氧化保护提前发生的结果。经钛盐-氟盐无铬钝化处理后铝线表面会形成较为致密、连续的保护膜,在保证铝单线的力学性能和电气性能均能满足国际标准要求的同时,保护导线表面不被氧化腐蚀而产生发黑现象。其次,当导线表面发生轻微磨损时,其抗腐蚀性能仍然优于未钝化的导线。

The outer surface of the conductors was generally oxidized and blacked unevenly in open air or during the transportation for a long time by the industrial atmospheric environment containing chlorine and sulphur and the dual action of high temperature and humidity.Micro-morphology and micro-area composition of the blackened conductors were analyzed by SEM and EDS.Moreover,the surface chromium-free passivation process of conductor was studied.Results showed that the process of oxidative blackening agreed with the oxidation process after power-on operation for several months,and it was a result of anticipation of oxidation protection.After chromium-free passivation,the denser and continuous protective film formed on the surface of the aluminium wire.Not only the protective film ensured the mechanical and electrical properties of the single aluminum wire could meet the requirements of the national standard,but also the surface of the conductor was also protected from oxidation corrosion and blackening.Secondly,when slight wear occurred on the surface of the conductor,the corrosion resistance was still better than that of the non-passivated conductor.