Effect of functional groups (methyl, phenyl) on organic–inorganic hybrid sol–gel silica coatings on surface modified SS 316
Effect of functional groups (methyl, phenyl) on organic–inorganic hybrid sol–gel silica coatings on surface modified SS 316
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DOI：
10.1016/j.ceramint.2012.05.040
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发表时间：
2012-12
影响因子：
5.2
通讯作者：
Nirmal Kumar;A. Jyothirmayi;K. Raju;R. Subasri
中科院分区：
文献类型：
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作者：
Nirmal Kumar;A. Jyothirmayi;K. Raju;R. Subasri
采用浸涂技术，将苯基三甲氧基硅烷、甲基三乙氧基硅烷和四乙氧基硅烷等有机改性硅烷前体水解缩合而成的有机-无机杂化溶胶-凝胶基二氧化硅涂层沉积在不同表面预处理（清洗、等离子处理、喷丸处理）的ss316级不锈钢基体上。涂层在空气中150℃热处理2h。利用x射线光电子能谱和扫描电镜对预处理后的表面进行了表征。用卡尔费歇尔滴定法测定溶胶的含水量，以评价水解和缩合反应的完成程度。对固化涂层的厚度、水接触角、铅笔划痕硬度、光泽度和涂层厚度的收缩率进行了表征。对用这两种硅烷前驱体合成的溶胶制成的涂料进行了冲击试验。对采用不同前驱体和不同表面处理方法制备的涂层进行了耐蚀性和耐水性试验。通过电化学极化测量，分别在3.5% NaCl溶液中进行1h和24h的腐蚀试验。结果表明，与苯基取代的三烷氧基硅烷相比，甲基取代的有机改性烷氧基硅烷涂层具有更好的疏水性、耐划伤硬度、耐冲击性和耐腐蚀屏障性能。两种有机改性硅烷前驱体在水解和缩聚速率上的差异解释了涂料性能的差异。
Organic–inorganic hybrid sol–gel based silica coatings derived from hydrolysis and condensation of organically modified silane precursors like phenyltrimethoxysilane and methyltriethoxysilane along with tetraethoxysilane were deposited on different surface pre-treated (as-cleaned, plasma-treated, shot-blasted) SS 316 grade stainless steel substrate, using dip coating technique. The coatings were heat treated at 150°C for 2h in air. The pre-treated surfaces were characterized using X-ray Photoelectron Spectroscopy and Scanning Electron Microscopy. The water content of the sols was determined by Karl Fischer titration to evaluate the degree of completion of hydrolysis and condensation reactions. Cured coatings were characterized to evaluate thickness, water contact angle, pencil scratch hardness, gloss, and shrinkage in coating thickness. Impact test was carried out on pigmented coatings derived from sols synthesized using the two silane precursors. The corrosion resistance and water durability tests were carried out to compare the coatings derived from using different precursors and different surface pre-treatments. The corrosion tests were carried out for 1h and 24h exposure to a 3.5% NaCl solution by electrochemical polarization measurements. It was found that coatings from methyl substituted organically modified alkoxysilane exhibited better hydrophobicity, scratch hardness, impact resistance and barrier properties with respect to corrosion, when compared to those derived from phenyl substituted trialkoxysilane. The difference in performance of coatings was explained on the basis of difference in hydrolysis and condensation rates between the two organically modified silane precursors used for the sol synthesis.