【作者】 闫斌；

【导师】 陈嘉宾；

【作者基本信息】 大连理工大学 ， 化学工程， 2008， 硕士

【摘要】 第二类吸收式热泵(AHT)是一种有效回收利用低品位热能的节能、环保型技术,具有显著的经济效益和社会效益。随着能源紧张及其价格的上涨,日益受到世界各国的重视。然而在高温高浓度下工质溴化锂对设备材料0Cr18Ni9不锈钢等的腐蚀更加严重,已经严重制约了AHT在高温领域的发展和应用。本文首次在0Cr18Ni9不锈钢表面利用提拉法制备了双功能性硅氧烷BMBSE膜,采用FT-IR、SEM、EPMA、极化曲线、EIS对膜层表面性能、结构等进行表征,并根据第二类吸收式热泵高温下的实际工况进行静态浸泡腐蚀实验,对薄膜在高温下的耐腐蚀能力进行研究。结果表明,双功能性BMBSE硅氧烷与不锈钢基体发生了化学键合,形成-Si-O-Fe键在不锈钢表面成膜。同时由于有机组分甲基和亚甲基的引入,结构均匀致密,并具有一定的疏水性;电化学测试结果表明BMBSE膜的极化阻抗比不锈钢大4个数量级,自腐蚀电流密度也下降低了4个数量级左右,具有良好的耐腐蚀性能;成膜的影响因素优化结果表明BMBSE、EtOH、D.I.water摩尔比为1∶4∶3,热处理温度为200℃时,更有利于制备结构均匀、致密、耐腐蚀性能好的薄膜;静态浸泡腐蚀实验结果说明,在180℃、55%的高温溴化锂溶液中BMBSE膜能起到良好的腐蚀防护作用。并进一步采用正硅酸乙酯(TEOS)对BMBSE膜的结构进行改进,在不锈钢表面制备了具有一定疏水性的更加致密的BMBSE/TEOS复合膜。研究表明TEOS的加入可以提高BMBSE膜与基底材料的交联点密度,薄膜更致密,腐蚀防护性能更好。实验表明,当TEOS摩尔含量比在2∶1时,BMBSE/TEOS复合膜具有最佳的腐蚀保护能力;在180℃、55%的高温溴化锂溶液中的腐蚀速度为5.64um/a,表现出比BMBSE膜更强的耐腐蚀能力。采用EIS考察了BMBSE膜及BMBSE/TEOS复合膜不锈钢试样在55%溴化锂溶液中有氧、室温条件下的腐蚀过程。两者都表现出良好的耐腐蚀性能,而BMBSE/TEOS膜具有更加优异的耐腐蚀能力和耐渗水性。更多还原

【Abstract】 The absorption heat transformer (AHT) is a energy conservation technology which converts low level energy and exhaust heat into high level energy. It has attracted more attention in the world-wide energy crisis recent years. Lithium bromide solutions, the commonly used absorbent solutions in heating and refrigerating absorption systems, can cause serious corrosion problems on metallic component, especially at high temperature, which has seriously restricted the development of AHT at high temperature.In this paper, functional bis-silanes BMBSE films were successfully prepared on 0Crl8Ni9 stainless steels substrates by Czochralski Method. The surface morphologies and structures of the film were studied by means of scanning electronic micrographs (SEM), contact angle measurement, Fourier transform infrared spectroscopy (FT-IR), and Electron probe x-ray micro analyzer (EPMA). The results showed that a perfect BMBSE film was produced by deposition of molecules attached to the metal surface by chemical bonds of Si-O-Fe between the BMBSE film and the 0Cr18Ni9 stainless steel. Meanwhile, the coated surface was hydrophobic with a contact angle of 107.2°since the introduction of methyl groups and methylene groups. Static immersing corrosion test, potentiodynamically polarization curve and electrochemical impedance spectroscopy (EIS) were conducted to evaluate the film corrosion performances. The results of potentiodynamically polarization curve and EIS in 55wt% LiBr solutions at room temperature in atmospherical pressure indicated that the corrosion current density of BMBSE film coated surface was 4 orders of magnitude smaller than that of bare SUS304 steel, and the impedance was increased by a factor of 10000. Static immersing corrosion test presented that the BMBSE film can significantly increase the corrosion resistance in 55wt%LiBr solution at 180°C compared with stainless steels.Furthermore, tetraethyl orthosilicate (TEOS) was added to improve the structure of BMBSE film. A hydrophobic composite film of BMBSE/TEOS was successfully prepared on 0Cr18Ni9 stainless steels substrates. The results showed that the introduction of TEOS increased the crosslinkage between composite films and substrates which led to a denser layer and further improved the anti-corrosion property of 0Cr18Ni9 stainless steels. The anti-corrosion property of BMBSE/TEOS composite film tended to peak with the molar ratio of BMBSE to TEOS being 2:1. Corrosion rate of BMBSE/TEOS composite film coated surface was 5.64um/a in 55wt%LiBr solution at 180℃, which was better than of BMBSE film coated one.EIS was applied to investigate the corrosion process of the BMBSE film and BMBSE/TEOS composite film coated 0Crl8Ni9 stainless steels in 55wt%LiBr solution at room temperature. Both of two films exhibit an excellent corrosion resistant property with the composite film being better.更多还原