KOH含量对赤泥等离子体电解氧化复合陶瓷层结构和结合强度的影响

Effect of KOH Content on Structure and Bonding Strength of Red Mud Plasma Electrolytic Oxidation Composite Ceramic Coatings

在KOH-赤泥电解液中对5005铝合金进行等离子体电解氧化(PEO),研究了KOH质量浓度(CKOH=1.0,2.0,3.0,4.0,5.0 g·L-1)对PEO临界起弧电压以及陶瓷层厚度、物相组成、形貌和结合强度等的影响。结果表明:不同KOH含量电解液中制备的陶瓷层主要由γ-Al2O3和α-Al2O3组成,但也出现了少量的Ca CO3、Si O2和Fe2O3等相。随着KOH含量的增加,PEO正负临界起弧电压快速降低;陶瓷层厚度呈"半抛物线"形增大;陶瓷层中γ-Al2O3含量先增加后减少再增加,α-Al2O3含量的变化趋势正好与之相反,Ca CO3、Si O2和Fe2O3含量则先增加后减少;陶瓷层表面孔隙率先降低后增大,表面粗糙度不断增大,硬度和结合强度先增大后减小。

Plasma electrolytic oxidation(PEO)of 5005 aluminum alloy was carried out in KOH-red mud electrolytes.Effects of KOH mass concentration(CKOH=1.0,2.0,3.0,4.0,5.0 g·L-1)on the critical arcing voltage of PEO and the thickness,phase composition,morphology and bonding strength of the ceramic coating were analyzed.The results show that the ceramic coatings prepared in electrolytes with different KOH content were mainly composed ofγ-Al2O3 andα-Al2O3,but a small amout of Ca CO3,Si O2and Fe2O3phases also appeared.When KOH content increased,the positive and negative critical arcing voltages of PEO decreased rapidly;the coating thickness showed a growth trend of"semi-parabolic"shape;theγ-Al2O3content in the ceramic coating increased first,then decreased and then increased,the change trend ofα-Al2O3content was just the opposite,and the Ca CO3,Si O2,Fe2O3content increased first and then decreased;the surface porosity of the ceramic coating decreased first and then increased,the surface roughness kept increasing and the hardness and bonding strength increased first and then decreased.