Silane coupling agent KH560 was used to modify the surface of nano-α-Al<sub>2</sub>O<sub>3</sub> in ethanol-aqueous solution with different proportions. The particle size of nano-α-Al<sub&...Silane coupling agent KH560 was used to modify the surface of nano-α-Al<sub>2</sub>O<sub>3</sub> in ethanol-aqueous solution with different proportions. The particle size of nano-α-Al<sub>2</sub>O<sub>3</sub> was determined by nano-particle size analyzer, and the effects of nano-α-Al<sub>2</sub>O<sub>3</sub> content, ethanol-aqueous solution ratio and KH560 dosage on the dispersion and particle size of nano-α-Al<sub>2</sub>O<sub>3</sub> were investigated. The material structure before and after modification was determined by Fourier transform infrared spectroscopy (FTIR). Aqueous polyurethane resin and inorganic components are combined with modified nano-α-Al<sub>2</sub>O<sub>3</sub> dispersion to form chromium-free passivation solution. The solution is coated on the galvanized sheet, the adhesion and surface hardness are tested, the bonding strength of the coating and the surface hardness of the substrate are discussed. The corrosion resistance and surface morphology of the matrix were investigated by electrochemical test, neutral salt spray test and scanning electron microscope test. The chromium-free passivation film formed after the modification of nano-α-Al<sub>2</sub>O<sub>3</sub> increases the surface hardness of galvanized sheet by about 85%. The corrosion resistance of the film is better than that of a single polyurethane film. The results show that the surface hardness and corrosion resistance of polyurethane resin composite passivation film are significantly improved by the introduction of nano-α-Al<sub>2</sub>O<sub>3</sub>.展开更多
文摘Silane coupling agent KH560 was used to modify the surface of nano-α-Al<sub>2</sub>O<sub>3</sub> in ethanol-aqueous solution with different proportions. The particle size of nano-α-Al<sub>2</sub>O<sub>3</sub> was determined by nano-particle size analyzer, and the effects of nano-α-Al<sub>2</sub>O<sub>3</sub> content, ethanol-aqueous solution ratio and KH560 dosage on the dispersion and particle size of nano-α-Al<sub>2</sub>O<sub>3</sub> were investigated. The material structure before and after modification was determined by Fourier transform infrared spectroscopy (FTIR). Aqueous polyurethane resin and inorganic components are combined with modified nano-α-Al<sub>2</sub>O<sub>3</sub> dispersion to form chromium-free passivation solution. The solution is coated on the galvanized sheet, the adhesion and surface hardness are tested, the bonding strength of the coating and the surface hardness of the substrate are discussed. The corrosion resistance and surface morphology of the matrix were investigated by electrochemical test, neutral salt spray test and scanning electron microscope test. The chromium-free passivation film formed after the modification of nano-α-Al<sub>2</sub>O<sub>3</sub> increases the surface hardness of galvanized sheet by about 85%. The corrosion resistance of the film is better than that of a single polyurethane film. The results show that the surface hardness and corrosion resistance of polyurethane resin composite passivation film are significantly improved by the introduction of nano-α-Al<sub>2</sub>O<sub>3</sub>.
文摘以固体A l2(SO4)3.nH2O为催化剂,在微波辐射下,以α-萘乙酸和甲醇为原料合成了α-萘乙酸甲酯。考察了催化剂的用量、微波功率、微波辐射时间、醇酸比对酯产率的影响。实验结果表明,最佳实验条件为:催化剂用量6%,微波功率600 W,微波辐射时间28 m in,醇酸摩尔比12∶1,酯产率72.45%。
