铝管表面混合硅烷稀土耐蚀复合膜的制备

Preparation of Hybrid Silane-Rare Earth Composite Coating on the Surface of Aluminum Tube

采用浸渍法制备了混合硅烷和稀土铈复合膜。在铝管试样表面组装一层双-[3-(三乙氧基)硅丙基]四硫化物(BTESPT)和乙烯基三甲氧基硅烷(VS)的混合硅烷薄膜,然后在膜上沉积稀土铈转化膜,制得硅烷稀土复合膜。通过点滴、盐雾、亲水角和Tafel极化曲线实验研究了复合膜层的耐蚀性。结果表明:与空白试样相比,亲水角角度明显增大;复合膜层的自腐蚀电流密度降低了2个数量级,抗蚀能力提高了3倍,其耐蚀性能比铬酸盐转化膜的还要好。扫描电子显微镜(SEM)显示:其复合膜层均匀、致密;EDS分析表明:复合膜主要由S,O,Si,Al和Ce等元素组成,并初步探讨了成膜机理。

A hybrid silane-rare earth composite coating on the surface of aluminum tube was prepared by impregnation method. The sample with a self-assembled monolayer of bis-[3-（triethoxysilyl）propyl] tetrasulfide （BTESPT） and vinyltriethoxy-silicane （VS） hybrid-silane was immersed in the rare earth cerium solution to get the complex coating. Corrosion resistance of aluminum tube surface with composite coating was investigated respectively by electrochemical means, hydrophilic contact angle, dropping corrosion and salt spray tests. The results show that compared with the blank, the hydrophilic contact angle increases evidently; Tafei polarization technique indicates that the self-corrosion current density decreases by two orders of magnitude; the result of salt spray test indicates that the anti-corrosion time increases by three times; the corrosion resistant capability is better than that of chromate conversion coating. Scanning electron microscope （SEM） observation indicates that the conversion coating is uniform and dense. X-ray energy dispersive spectroscopy （EDS） test indicates that the complex coating is mainly composed of S, O, Si, Al and Ce. The formation mechanism of the composite coating is preliminarily discussed.