材料(liao)與周圍非(fei)電解質(zhi)之間發(fa)(fa)生純(chun)化學作用而(er)引起的(de)腐(fu)(fu)蝕(shi)(shi)損傷稱為(wei)化學腐(fu)(fu)蝕(shi)(shi)。其(qi)反應(ying)(ying)特(te)點(dian)是材料(liao)表面(mian)的(de)原子與非(fei)電解質(zhi)中的(de)氧化劑直接發(fa)(fa)生氧化還原反應(ying)(ying),腐(fu)(fu)蝕(shi)(shi)產(chan)物生成于發(fa)(fa)生腐(fu)(fu)蝕(shi)(shi)反應(ying)(ying)的(de)表面(mian),當它較牢固地覆蓋在材料(liao)表面(mian)時,會減緩(huan)腐(fu)(fu)蝕(shi)(shi)的(de)進(jin)一步發(fa)(fa)生。腐(fu)(fu)蝕(shi)(shi)反應(ying)(ying)過程(cheng)中無電流產(chan)生。

  金屬和電(dian)解質(zhi)接觸時(shi),由于(yu)腐蝕(shi)(shi)(shi)(shi)(shi)(shi)(shi)電(dian)池作(zuo)用而(er)引起的(de)金屬腐蝕(shi)(shi)(shi)(shi)(shi)(shi)(shi)現(xian)象稱為電(dian)化(hua)(hua)學(xue)腐蝕(shi)(shi)(shi)(shi)(shi)(shi)(shi)。腐蝕(shi)(shi)(shi)(shi)(shi)(shi)(shi)的(de)特點在于(yu),腐蝕(shi)(shi)(shi)(shi)(shi)(shi)(shi)歷程可(ke)(ke)分(fen)為兩個相對(dui)獨立(li)的(de)并同時(shi)進行的(de)陽(yang)極(ji)和陰極(ji)過程。特征為受蝕(shi)(shi)(shi)(shi)(shi)(shi)(shi)區是(shi)金屬表面的(de)陽(yang)極(ji),腐蝕(shi)(shi)(shi)(shi)(shi)(shi)(shi)產(chan)物(wu)常常產(chan)生(sheng)(sheng)在陽(yang)極(ji)與陰極(ji)之間,不(bu)能覆蓋被蝕(shi)(shi)(shi)(shi)(shi)(shi)(shi)區域,通(tong)(tong)常起不(bu)到保護作(zuo)用。電(dian)化(hua)(hua)學(xue)腐蝕(shi)(shi)(shi)(shi)(shi)(shi)(shi)和化(hua)(hua)學(xue)腐蝕(shi)(shi)(shi)(shi)(shi)(shi)(shi)的(de)顯著(zhu)區別是(shi)腐蝕(shi)(shi)(shi)(shi)(shi)(shi)(shi)過程中有電(dian)流產(chan)生(sheng)(sheng)。對(dui)于(yu)大多數工(gong)業部門(men)而(er)言,發生(sheng)(sheng)電(dian)化(hua)(hua)學(xue)腐蝕(shi)(shi)(shi)(shi)(shi)(shi)(shi)的(de)情況遠多于(yu)發生(sheng)(sheng)化(hua)(hua)學(xue)腐蝕(shi)(shi)(shi)(shi)(shi)(shi)(shi)的(de)情況。金屬發生(sheng)(sheng)高(gao)溫氧化(hua)(hua),表面生(sheng)(sheng)成一定(ding)厚(hou)度的(de)半導體(ti)性(xing)質(zhi)的(de)氧化(hua)(hua)膜,既(ji)可(ke)(ke)以傳(chuan)導電(dian)子,也可(ke)(ke)以導通(tong)(tong)離子,此(ci)時(shi)腐蝕(shi)(shi)(shi)(shi)(shi)(shi)(shi)不(bu)再是(shi)單純的(de)化(hua)(hua)學(xue)腐蝕(shi)(shi)(shi)(shi)(shi)(shi)(shi),而(er)且還包(bao)含了電(dian)化(hua)(hua)學(xue)腐蝕(shi)(shi)(shi)(shi)(shi)(shi)(shi)。