Study On The Preparation Of Water Based Silanization Solution And Its Application In Metal Surface Treatment

Silanization of metal surface could significantly improve the corrosion resistance of materials and adhesion of paints upon substrates. And it has been studied as environmentally friendly surface treatment technology for replacing the pollutive chromate conversion chromating and phosphating treatments. In this paper two kinds of silanization solutions were prepared and the corrosion protection performance of silane treated standard cold-rolled plates and bonding property to organic coatings were studied.Choose two silane hydrolysis in the solvent, define the process parameters and obtain two silylation treatment agent. The hydrolysis degree of silanes was reflected by using the conductivity testing method on-line solution system. It was found out that the stability of silane solution was related to hydrolysis solvents, hydrolysis time, concentration, pH value, temperature, additive. In order to obtain more silanol, hydrolyzing in mixing solvent with water and ethanol(or methanol) had great better effect than only in pure water or ethanol. KH-550:water:ethanol using1:(1-3):(5-15) ratio is the optimum concentration of the hydrolysis, KH-792:water:methanol concentration ratio is1:(4-6):(8-15). Both hydrolysis time control within2h, the optimum hydrolysis temperature was between20to40℃,pH value of9to11,additive amount is0.15g/L.The silane films were prepared by substrates dipping in silane solution and then curing at high temperature. The influence of the preparation process of films on the properties of films verified by measuring and testing anti-corrosion capability of films. The chemical structure and property of silane films were characterized and analyzed by a series of detection methods which included XPS(X-ray photoelectron spectroscopy), SEM(scanning electron microscope) and DSC. At the same time, the thermal decomposition temperature of KH-550K and H-792films was studied. The capability of anti-corrosion of films equivalent to industrial product8011A.Dipping time is2min, curing temperature is100℃, curing time is0.5h. The films had more excellent performance of anti-alkali and worse performance of anti-acid.Effect of various condition on the adhesive strength between organic coatings and substrates was studied. Resistance to salt spray test, adhesion test, cupping test, impact test are all qualify, the results indicated that cold rolled sheet substrate and coating have a good bonding properties.