铝管外壁的阳极氧化及膜的性能

Anodizing of the Outer Wall of Aluminum Pipe and Corrosion Resistance of the Anodizing Film

传统的铝管材阳极氧化,需作封口等处理,工艺繁琐,成本高。探讨了一种在外加电场作用下,只在铝管外壁制备阳极氧化膜的工艺,并对其原理进行了分析。20℃时,将铝管材在直流恒电流密度为1.7A/dm2下电解40min,制备成氧化膜,后经95℃水封孔15min。结果表明:该氧化膜层耐K2Cr2O7点滴53min,开始析氢时间为10.2h,碱浸失重速率为60mg/(m2.h)。本工艺制备的氧化膜耐蚀性比普通阳极氧化膜稍差,但远远优于铬酸盐转化膜,与普通的氧化工艺相比,本工艺制备氧化膜更加简单、经济。

The technology to prepare anodizing film on the outer wall of aluminum pipes in the pres-ence of external electric field was explored,and the principle was analyzed.Thus the Al pipes were firstly electrolyzed at a temper-ature of 20 ℃ and constant direct current density of 1.7 A/dm2 for 40 min,allowing the generation of initial oxidation film.The initial oxidation film was then sealed in water at 95 ℃ for 15 min generating the target porous oxide film.The corrosion resistance of the final oxide film was evaluated.Results indicate that the present porous oxide film is endurable to dripping K2Cr2O7 for up to 53 min.Its time for hydrogen evolution is as much as 10.2 h,while its weight-losing rate in alkaline amounts to 60 g/(m2 · h).This means that the present porous oxide film has much better corrosion resistance than chromate conversion coat-ing,though it is somewhat disadvantageous over conventional anodizing film.Moreover,the present process is more simple and economical as compared with conventional oxidizing process.