Objective To study the preparation of trivalent chromium passivation agent and its corrosion resistance. Methods A kind of trivalent chromium passivation agent was prepared on the surface of galvanization with background film-former( a chromium anhydride),reducing agent( tartaric acid sodium),additive( inorganic mixed acid) and hole sealing agent( nano silica). The corrosion resistance of the passive film was studied by neutral salt spray test( NSS),tafel polarization and ac impedance( EIS) tests; and the surface morphology and elemental composition of passive film were analyzed by scanning electron microscopy( SEM) and energy spectrum analyzer( EDS). Results The results showed that the corrosion area of 120 h NSS experiment was below 5%. Compared with the corrosion potential( 1. 015 V) of the galvanized sheet without passivation,the self-corrosion potential( 0. 965 V) had positive displacement,and the corrosion current density decreased by about two orders of magnitude,from 8. 458 × 10- 4A / cm2to 6. 356 × 10- 6A / cm2. The corrosion resistance of galvanized sheet after passivation was greatly increased. SEM test showed that membrane surface was smoother with white particle deposition; EDS experiment indicated that passivated membrane mainly contained C,O,Si,Cr and Zn. XPS showed the Cr compounds were mainly trivalent and hexavalent,while the zinc compounds were mainly bivalent. Conclusion The passivation agent could improve the corrosion resistance of the galvanized sheet and has great industrial value.
研究一种可直接用于已生锈钢材表面的转化型带锈涂料,该带锈涂料具有水溶性、不易燃、环保等优点.利用质量法确定正交试验最优配方,采用中性盐雾试验、电化学测试和漆膜划格法附着力测试等手段进行带锈涂料性能测试,并与市售带锈涂料进行防锈性能对比试验.结果表明,水溶性转化型带锈涂料的附着力可达一级,与市售带锈涂料相比,Q235样钢的极化曲线腐蚀电位正移,腐蚀电流减小,腐蚀速率降低.耐中性盐雾试验可达48h,耐质量分数为5％的盐水浸泡可达48h.
The anatase type TiO2 nanotubes were prepared on Ti surface by electrchemical anodic oxidation method.Using the TiO2 nanotube membrane as anode,the factors affecting photoelectrocatalytic degradation of acid orange were studied.The experimental results show that:Under the optimum conditions of solution pH 3.0,external bias potential 2.5 V,NaCl concentration 0.05 mol/L and reaction time 30 min,the acid orange degradation rate can reach 99.99%;After the TiO2 nanotubes is reused for 25 times,the acid orange degradation acid orange degradation rate can still reach 94.57%.
