6061铝合金表面氟钛酸盐改性硅烷膜的耐蚀性能

Corrosion Resistance of 6061 Aluminum Alloy Silane Film Modified with Hexafluorotitanate

为进一步提高铝合金表面硅烷转化膜的耐蚀性能,采用氟钛酸盐改性硅烷形成复合转化液,并在6061铝合金表面制备硅烷-氟钛酸盐转化膜。采用极化曲线、CuSO_4点滴试验、盐水浸泡试验及盐雾试验评价转化膜的耐蚀性;研究了氟钛酸盐用量对复合膜耐蚀性的影响,并比较了单一转化膜和复合转化膜的耐蚀性。结果表明:氟钛酸盐的最佳用量为1.0×10^(-3)mol/L,此时复合膜的自腐蚀电流密度最小,极化电阻最大,腐蚀面积最少,耐CuSO4点滴时间最长,最佳氟钛酸盐用量下改性硅烷复合膜的自腐蚀电流密度相对于硅烷转化膜下降了1个数量级,24h中性盐雾后表面几乎没有白锈产生,盐水浸泡的腐蚀速率最小。

In order to improve the corrosion resistance of silane film on aluminum alloy, the hexafluorotitanate-modified silane was designed as composite conversion solution, and then the silane-hexafluorotitanate conversion film was obtained on the surface of 6061 aluminum alloy. The corrosion resistance of conversion film was characterized by polarization curves, CuSO4 drip test, salt water immersion test and salt spray test. Moreover, the effect of hexafluorotitanate concentration on the corrosion resistance of composite film was studied, and the corrosion resistance of single conversion film and composite film was compared. Results showed that the optimal concentration of hexafluorotitanate was 1.0× 10^-3 mol/L, and the as-prepared film had the minimum self-corrosion current density, the maximum polarization resistance, the least corrosion area and the longest resistance time of CuSO4 drop test. The corrosion current density of modified silane film prepared with the optimal concentration of hexafluorotitanate decreased by 1 order of magnitude in comparison with that of silane film. Furthermore, after neutral salt spray for 24 h, little white rust generated on the surface of aluminum alloy, and the corrosion rate in salt water was the smallest.