酸度对钝化液稳定性影响的理论预测  

Theoretical Prediction on the Effect of Acidity on Stability of Passivation Solution

作　　者：徐孟进 冯慧杰 郭安儒[4] XU Meng-jin;FENG Hui-jie;GUO An-ru(Lucky Film Co.,Ltd.,Baoding 071054,China;Hebei New Energy Membrane Materials Technology Innovation Center,Baoding 071054,China;Baoding New Energy Membrane Materials Technology Innovation Center,Baoding 071054,China;Aerospace Research Institute of Materials&Processing Technology,Beijing 100076,China)

机构地区：[1]乐凯胶片股份有限公司,河北保定071054 [2]河北省新能源膜材料技术创新中心,河北保定071054 [3]保定市新能源膜材料技术创新中心,河北保定071054 [4]航天材料及工艺研究所,北京100076

出　　处：《材料保护》2022年第2期60-68,共9页Materials Protection

摘　　要：为了理论预测酸度变化时钝化液的稳定性,从沉淀溶解平衡、配位解离平衡和电离水解平衡出发,同时考虑离子强度的影响,建立了钝化液溶液中各物质之间的物料守恒和质子守恒方程式,通过求解多元高次方程组,得到在一定物料配比下钝化液中各组分的含量,计算出酸度值,同时通过溶度积常数来判断在该酸度下钝化液中是否有沉淀出现来预测钝化液的稳定性。通过理论计算和试验结果对比发现:在pH=2.3~3.0范围内,钝化液体系pH值的计算值和试验值的吻合性较好,误差值小于10%;试验配制的钝化液随着酸度的降低,在pH≥2.5时开始变得不稳定而出现浑浊和沉淀,与计算得到的在pH≥3.0出现的沉淀现象大体上吻合;随着钝化液浓度的降低,钝化液体系pH值的理论值更加接近实验值,并且出现沉淀时两者的误差更小。建立的钝化液溶解沉淀模型能反映钝化液的酸度对其稳定性的影响规律。依据该浓度预测模型,通过计算金属铝在钝化液中持续溶解时酸度动态上升引起的不同难溶盐的沉淀过程,可将该模型应用到推测铝合金/钝化层界面层的结构,对深入理解铝合金的防腐机理有指导意义。For theoretically predicting the stability of the passivation solution with changing acidity,based on the equilibria of precipitation-dissolution,complexation-dissociation and ionization-hydrolysis,and considering the effect of ionic strength,the equations of the material balance and the proton balance for all the substances in the passivation solution were established.By solving the multivariate high order equations,content of all the substances in passivation solution were obtained under a certain material ratio,the acidity value was calculated.The stability of the passivation solution was predicted by judging whether there was precipitation in the passivation solution at this acidity through the solubility product constant.Comparing the theoretical calculation with the experimental result,it could be found that in the range of pH=2.3~3.0,the calculated value of pH of passivation solution was in good agreement with the experimental data,and the error was less than 10%.With the decrease of acidity,the passivation solution prepared in the experiment became unstable when pH≥2.5 and resulting in cloudiness and precipitation,which was generally consistent with the precipitation phenomenon at pH≥3.0 in calculated prediction.With the decrease of the concentration of the passivation solution,the theoretical pH value of the passivation solution was closer to the experimental data,and the error between the theoretical pH value and experimental pH value was smaller when the precipitation occurred.Therefore,the established dissolution and precipitation model of passivation solution could reflect the influencelaw of the acidity on the stability of the passivation solution well.According to this concentration prediction model,the precipitation process of different insoluble salts caused by the dynamic increase of acidity during the continuous dissolution of aluminium in passivation solution could be calculated and the model could be used to infer the interface layer structure between aluminium alloy and passivation layer

关 键 词：钝化液 酸度 稳定性 沉淀 溶解 理论计算 钝化层 界面结构 

分 类 号：TG174.44[金属学及工艺—金属表面处理]