Abstract
台灣潮濕且含鹽份的大氣環境容易造成金屬腐蝕，其鋼鐵結構物的大氣腐蝕因此成為嚴重的問題。為延長鋼鐵結構的使用壽年並降低其維護費，發展各種耐候鋼與適當的保護塗漆，乃成為重要的研究議題。本文首先比較碳鋼(SS400)與高磷含量的耐候鋼(Acr-Ten A)在台灣不同大氣環境中，長期 (6年)曝露之腐蝕行為差異。發現耐候鋼在工業環境中的腐蝕行為較為特殊；曝露 3年後，耐候鋼的腐蝕速率大輻降低，其大氣腐蝕行為已脫離一般的雙對數線性關係。此一腐蝕異常現象對於預測耐候鋼長期腐蝕速率，影響至鉅。本文發展在二氧化硫中乾濕交替循環的加速腐蝕實驗方法，以模擬耐候鋼在工業環境中的異常腐蝕行為。同時，應用 EIS與改良三極式薄膜電化學偵測技術，研究鋼材在二氧化硫氣氛中的腐蝕行為變化現象；並將其電化學阻抗之經時變化情形，以適當的等效電路加以模擬探討。另外，本文亦以EIS技術評估預測塗漆鋼材的大氣曝露腐蝕行為。Atmospheric corrosion of steel structures is a serious prob-lem in Taiwan, this is ascribe to the humid and saltyenvironme- nts which is mostly aggressive for metalliccorrosion. In order to prolong the service life ofsteelstructures and maintain it ecomomically,the development ofweathering steels as well as the suitable protective paints isof particular importance in Taiwan The atmospheric corrosionperformance of carbon steel (SS400)and high phosphorusweathering steel (Acr-Ten A) exposed in differe- nt atmosphericenvironments were studied and compared after exp- osure forvarious periods up to 6 years in Taiwan. In an indust- rialatmosphere, the corrosion rate of weathering steel decreas- edmarkedly after 3 years' exposure. Meanwhile, the corrosionkinetics of weathering steel was found to be deviated fromthe behavior predicted by the well - known biloga rithmic law.This abnormal atmospheric corrosion behavior is especiallyimportant in predicting the long term corrosion rate ofweathering steel. A laboratory accelerated test withalternating wet/dry cycl- es in SO2 was consequentlydeveloped to simulate the abnormal atmospheric corrosionbehavior of weathering steel in the indus- trial site.Furthermore, in-situ EIS measurements were carried out in amodified three-electrode cell covered by a thin electr- olytelayer to investigate the transiton of atmospheric corrosi- onbehavior of the tested steels. Changes of impedance behaviorswith exposure time were observed and subsequenyly modelledby their respective equivalent circuits. On the other hand,evalua- tion and prediction of the performance of painted steelfor atm- ospheric exposure were also conducted by EIStechniques.