Al(OH)_3溶胶浓度对TC4钛合金微弧氧化膜特性的影响

Effect of Al(OH)_3 sol concentration on characteristics of microarc oxidation coatings of titanium alloy

利用自制多功能微弧氧化(MAO)电源,在保持电学参数和处理时间不变的条件下对TC4钛合金表面进行了MAO处理,研究了Al(OH)3溶胶浓度对钛合金MAO膜的生长特性、微观结构、相结构和电致变色特性的影响.结果表明:随着Al(OH)3溶胶浓度(体积分数)C的增加,膜层的生长速率由慢到快逐渐增加,膜表面微孔尺寸和粗糙度逐渐增大,而微孔密度逐渐减小;当C≤10%时,膜层由锐钛矿相TiO2组成,而当C>10%时,膜层中开始出现金红石相TiO2并随着C的增加其相对含量逐渐增大,并在C=40%时,膜层全部由金红石相TiO2组成;在pH=2.0的HCl溶液中的循环伏安测试结果表明,C≤20%制备试样的膜层颜色变化不明显,随着C的进一步增加,制备试样的膜层颜色变化逐渐明显,并在C=40%时,其着色呈蓝色且色泽均匀;该试样在循环伏安测试过程中还表现出了良好的稳定性和可逆性.

The effect of Al （ OH ）3 sol on the growth characteristics, microstructure, phase structure and electrochromic properties of the coating fabricated on titanium alloy substrates were investigated by means of changing the Al（ OH）3 sol concentration. The results show that the rate of growth of coating thickness gradually increased from slow to fast with the increasing concentration of Al （ OH ）3 sol and the roughness and size of micropore on the coating surface gradually increased,while its pore density was reduced. The coating was composed of anatase TiO2 when the volume fraction C≤ 10% . The rutile TiO2 began to emerge at C 10% ,and its relative content gradually increased with the increase of the Al （ OH）3 sol concentration. When C = 40% ,the obtained coating was composed of rutile TiO2. The cyclic voltammetry tests in pH 2. 0 HCl solution showed that the color of the sample fabricated at C≤20% did not change significantly,with the increase of the Al（OH）3 sol concentration,the color change of the sample became clear. When C = 40% ,the obtained sample showed good stability and reversibility between blue coloration and bleaching cycles in pH 2. 0 HCl solution.