LY12铝合金的长期大气腐蚀行为

LONG-TERM ATMOSPHERIC CORROSION BEHAVIOR OF LY12 ALUMINIUM ALLOY

通过5种典型大气环境下为期20年的现场暴露试验,研究了LY12铝合金在我国长期大气腐蚀的规律和行为。结果表明,LY12在湿热的万宁和琼海分别暴露6年和10年后就发生了剥蚀,暴露20年后几乎丧失了力学性能,而在北京暴露20年后未出现剥蚀,仍保持良好的力学性能。LY12在大气污染物较多的江津和青岛腐蚀失重较大,在北京的腐蚀失重最小。剥蚀发生之前,LY12的腐蚀失重随暴露时间的变化遵循幂函数C=KT^n。剥落腐蚀产物中除Al屑之外主要为γ-Al(OH)_3和α-Al_2O_3·3H_2O。

Atmospheric corrosion behavior of LY12 was investigated in five typical atmospheres in China over 20 years. Mass loss and loss in mechanical properties were measured; Appearance, cross-section photomicrograph and corrosion products were observed and analyzed by optical microscope and XRD. The results show that in hot and humid atmosphere of Wanning and Qioughai exfoliation corrosion occurred on LY12 after 6 and 10 years, respectively, and almost lost its mechanical properties after 20 years exposure. While in Beijing atmosphere, LY12 still performed excellent mechanical properties after 20 years exposure. The mass loss data were higher in Jiangjin and Qingdao due to higher average RH and SO2 or Cl^- contamination of the atmosphere, and lowest in Beijing atmosphere because of lower average RH. Before exfoliation corrosion occurred, the mass loss data with exposure time obeyed well with power function C=KT^n. The main exfoliation corrosion products are γ-Al（OH）3 and α-Al2O3·3H2O.