Influence of nano-SiO_2 on polyurethane varnish

Hydrophobic nano-SiO_2 particles were prepared by surface modification,and the diameter of nano-SiO_2 was about 50nm.By using stiring and ultrasonic dispersing,nano-SiO_2 composite coating was obtained by adding nano-SiO_2 into polyurethane varnish.Immersion experiment,linear sweep voltammetry and electrochemical impedance were applied,the results showed that the anti-corrosion of nano-composite coating was improved by adding modified nano-SiO_2.It was obtained that the adhesion of coating was improved by adding modified nano-SiO_2 too.In addition,the films of coating were characterized by ultraviolet spectrophotometer(UV),the film of composite coating shows strong ability of UV adsorption,the ultraviolet resistance of polyurethane varnish was improved.