热镀锌合金化镀层的电化学特性及耐腐蚀性

Electrochemistry characteristics and corrosion resistance of galvannealed steel sheet

采用电化学阻抗谱法,分析了不同合金化热镀锌钢板在3.5wt%NaCl溶液中的腐蚀行为。结果表明,镀层充分合金化且具有适当比例的Zn-Fe金属相才具有良好的抗腐蚀能力。Zn-Fe合金相中铁的比例越高,其平衡电位越高,热力学稳定性越好。合金化时间不同时,生成两种具有不同电化学特性的相结构,一种为合金化不完全的η相,一种为合金化完全的ζ相,在含Cl-的溶液中,ζ相易于发生点蚀。锌液中铝含量为0.13wt%时,GA镀层和纯锌镀层均表现出较好抗腐蚀性。

Corrosion behavior of galvannealed steel sheet prepared at different galvannealing parameters in 3.5wt% NaCl solution was analyzed by electrochemical impedance spectroscopy. The results show that the galvannealed coating performs excellent corrosion resistance, when it has been sufficient galvannealed and has an appropriate proportion of Zn-Fe intermetallic compounds. The higher the iron content in the Zn-Fe intermetallie compound, the higher the equilibrium potential, the better the thermodynamics stability. Two different electrochemistry characteristic phase on the surface of galvannealed coatings can be generated with different galvannealing time, one is incomplete galvannealed η-phase, and the other is complete galvanncaled E-phase, and the latter is easy to occur spot pitting in solution containing Cl-. Both the galvanealed coating and galvanized coating performs excellent corrosion resistance, when the aluminum content in the zinc bath is 0.13wt%.