碳鋼與耐候鋼銹層和安定化處理膜的電化學行為研究

An Electrochemical Study of Rust Films and Stabilizers on Carbon and Weathering Steels

本文主要研究SS41和Acr-TcnA分別在4個不同環境大氣曝露3.5年後生成銹層及其安定化處理膜之腐蝕行為。交流阻抗結果顯示耐候鋼銹層之頻譜有兩個半圓，等效電路分析出兩個RC迴路，表示銹層具有保護底材之能力，反之，碳鋼銹層不具保護性，鈍化膜電阻趨近於零，等效電路僅有一個RC迴路。經安定化處理的試片，Nyquist圖僅有一個半圓並伴隨著擴散尾，此時真正的Rct將不易求出。開路電位量測結果顯示不同的安定化處理膜其電化學行為有所差異，詳細的保護機構可由Ellingham圖來解釋。而此些電化學行為亦在銹層及漆膜之SEM金相觀察中印證。另外，研究結果也證實以耐候鋼為底材之處理膜的抗大氣腐蝕性質有顯著之提高。

The corrosion behavior of rust films and stabilizers on carbon and weathering steels exposed in four different environments for 3.5 years has been investigated. AC impedance results indicate that the rust film on weathering steel has good performance to protect the base metal. On the other hand, the rust on carbon steel has bad protective property. The real charge transfer resistance of stabilizers cannot be estimated, although their Nyquist plots demonstrate one semicircle following a diffusion tail. Open circuit potential measurement results show that the electrochemical characteristics of different stabilizers are different but all of their protective mechanisms can be explained by Ellingham diagram. At the same time, these electrochemical behaviors of rust films and stabilizers were also identified by SEM observation. Besides, the atmospheric corrosion resistance of stabilizers on weathering steel is better than those on carbon steel.