6061铝合金微弧氧化陶瓷层生长速度

Growing Rate of Micro-arc Oxidation Coating on 6061 Aluminum Alloy

以变形铝合金6061为实验材料,在六偏磷酸钠质量浓度为8 g/L、硅酸钠质量浓度为5 g/L的溶液中,研究了电流密度、占空比、样品尺寸和溶液温度等因素对微弧氧化陶瓷层生长速度的影响。结果表明,电流密度越大,样品表面的电压越高,高电压提高了陶瓷层被击穿继续发生内部氧化的能力,陶瓷层生长速度随电流密度的增加以1.425×10-9m3/(min.A)的速率线性上升。占空比大小对陶瓷层生长速度几乎无影响,各占空比条件下的生长速率接近0.5μm/min,而电压随着占空比的减小发生微小的上升。不同尺寸样品的陶瓷层生长速率均约为0.31μm/min,但是电压随样品尺寸增大而升高。溶液温度升高提高了溶液中HSiO3-和H2PO23-离解程度,增强了溶液的导电能力和离子的扩散能力,使陶瓷层的生长速度加快,10、20和30℃下的生长速度分别为0.35、0.38和0.41μm/min。

In a solution containing 8 g/L sodium hexametaphosphate and 5 g/L sodium silicate, the influences of current density, duty cycle, sample dimension and solution temperature on the growing rate of MAO coatings on 6061 aluminum alloy were investigated. The results indicate that under high current density and voltage on sample surface, the growing rate of the coating increases linearly at a rate of 1. 425 0 × 10^-9 m^3/（min · A） with the increasing of current density due the ability of high voltage to break down the MAO coatings that are continuously oxidized. Duty cycle has no impact on the growing rate of the coating, and the growing rates of different duty cycles are approximately 0. 50 μm/min, but the voltage rises slightly with decreasing duty cycle. Growing rates of different dimension samples are 0. 31 μm/min, while voltage increases with the increase of the sample size. The rising of solution temperature enhances the dissociation degree of HSiO3^- and H2PO3^2- , improving the conductions of solution and ion diffusivity, which increases the growing rate of coating, and the growing rates under 10 ℃, 20 ℃ and 30 ℃ are 0. 35 μm/min, 0.38 μm/min, 0.41 μm/min, respectively.