NaOH对铝合金微弧氧化膜特性的影响

EFFECTS OF NaOH ON CHARACTERISTICS OF COATINGS ON ALUMINUM ALLOY BY MICRO-ARC OXIDIZATION

在Na_2SiO_3电解液体系下,对ZAISil2Cu2Mg1微弧氧化膜的形成进行研究,通过改变NaOH的含量,研究了其对电解液的电导率、微弧氧化的临界起弧电压、膜层特性及微观形貌的影响。并测定了氧化膜的相组成。结果表明:NaOH含量从1.0 g/L到3.0 g/L变化时,电解液的电导率由14.00 ms/cm几乎呈线性增大到26.28 ms/cm,正向临界起弧电压由360 V呈线性降低下降到290 V;含量从1.0 g/L增大到2.5 g/L时,膜厚从92μm迅速增加到125μm。含量超过2.5 g/L,膜厚减小,致密层所占比例下降。XRD分析表明:氧化膜层中主要由莫来石、SiO_2和α-Al_2O_3、y-A1_2O_3和WO_3相。

Forming of ceramic coatings on surface of ZAlSi2Cu2Mgl by micro-arc oxidization （MAO） in a Na2SiO3 electrolyte was investigated. The influences of content of NaOH on the conductivity of electrolytes, arc starting voltage, thicknesses of ceramic coatings, and morphology of coatings were analyzed respectively. Phase compositions of coatings were analyzed by XRD. The results show that while content of NaOH rises from 1.0 g/L to 3.0 g/L, the conductivity of electrolytes rises from 4.00 ms/cm to 26.28 ms/cm, and arc starting voltage decreases from 360 to 290 V. While the content of NaOH rises from 1.0 g/L to 2.5 g/L, the thickness of coatings increase gradually from 92 to 125 μm. But as the content of NaOH exceeds 2.5 g/L, the thickness and the proportion of compact layer decreases. The XRD result indicated that the coatings are composed of mullite, SiO2, α-Al2O3, γ-Al2O3 and WO3.