Research Progress And Rare-earth Modified Silane Silm On6061Aluminum Alloy

Silanes have unique structure with hydrolysable alkoxy group and organic functionality which can becombined with other materials. They are widely used as adhesives, aquaseal and surface treating agent onglass. Since1990s, silanes were applied on metal surface protection. Researchers found that silanes couldefficiently protect metals against different forms of corrosion. Now silane film are usually prepared on colerolled steel, galvanized steel, magnesium alloy and so on. This paper mainly studied the process of makingsilane film on6061aluminium alloy surface and the properties of modified silane film by adding rare earth.The filming process and characteristics were investigated in3.5%NaCl solution, using Tafelpolarization curves, dropping corrosion test, solution immersion test and scanning electron microscopy.The γ-Aminopropyltriethoxysilane film was deposited on6061aluminium alloy surface. Theelectrical conductivity results showed that silane solution was stable when the solution concentrationwas3%, pH value was12, the ratio of the ethanol to water was22:75and hydrolysis of72hours atroom temperature. Polarization curve test results and dropping corrosion test showed that the obtainedsilane films on6061aluminium alloy surface had good corrosion resistance, performing of thecorrosion current density reduce and corrosion potential rise when aluminum alloy specimen in silanesolution dip-coating3minutes, curing temperature180℃,curing time120min.The paper also investigated γ-methacryloxypropyltrimethoxysilane film which was deposited on6061aluminium alloy surface. The electrical conductivity results and dropping corrosion test showedthat silane solution was stable when the solution concentration was8%, pH value was4, the ratio ofthe ethanol to water was22:75and hydrolysis of12hours at room temperature. Polarization curve testresults showed that the obtained silane films on6061aluminium alloy surface had good corrosionresistance, performing of the corrosion current density reduce and corrosion potential rise when aluminumalloy specimen in silane solution dip-coating3minutes, curing temperature120℃,curing time60min.The experiments compared the optimal process condition and the corrosion resistances of the silanefilm between γ-Aminopropyltriethoxysilane(KH-550) and γ-methacryloxypropyltrimethoxysilane(KH-570). The results indicated that the two kinds of silane films on6061aluminium alloy had good corrosion resistance. The γ-Aminopropyltriethoxysilane(KH-550) silane films had better protection, thesilane solution can be stored for a longer time and much stable than γ-methacryloxypropyltrimethoxysilane(KH-570).On the basis of the optimal process condition of γ-methacryloxypropyltrimethoxysilane(KH-570), rareearth was adding in the silane solution to prepare modified silane films. CeCl3, YCl3and LaCl3were addinginto the silane solution, the concentration of each rare-earth chloride were0.0%,0.04%,0.2%and0.4%.According to the results, modified silane films had different degree of corrosion resistance, when theconcentration of each rare-earth chloride were different. The results indicated that when the concentrationof each rare-earth chloride was0.2%, the modified silane films had the best corrosion resistance, and theoptimal dffect was CeCl3.