產品長期暴露在空氣中，在自然條件的作用下，可能導致材料或性能被破壞或變質，這是自然的腐蝕效果。發生腐蝕的原因往往和環境中的氧氣、溫濕度、污染物等腐蝕成分有關。其中，鹽霧腐蝕就是最常見且破壞力很大的腐蝕。 鹽霧測試的作用 鹽霧是如何腐蝕金屬材料的?這是因為鹽霧中含有氯離子，可以穿透金屬表面的氧化層和防護層，直接與金屬層發生電化學反應，引起腐蝕。而且氯離子含有一定的水合能，很容易被金屬表面的空隙吸附，并取代氧化層中的氧，把不溶的氧化物變成可溶的氯化物，使本來具有防護性能的表面層變得活潑。 既然產品可能會受到鹽霧的腐蝕，那么在出廠前，就需要評估其耐腐蝕性能，評價其使用壽命。 鹽霧測試的種類 鹽霧測試可以采用天然環境暴露或人工加速模擬鹽霧環境進行試驗。天然環境暴露是最接近真實使用情況的方法，但缺點是試驗時間太長，可能廠家無法承受其時間成本。而人工加速模擬鹽霧環境試驗則是利用鹽霧試驗箱，將產品放置于試驗箱中，模擬鹽霧環境對產品的耐鹽霧腐蝕性能進行考核。 與天然環境相比較，人工鹽霧測試可以控制鹽霧濃度，使腐蝕速度大大提高，縮短試驗時間。以目前的技術條件來說，天然環境中需要測試一年以上的產品，在人工模擬鹽霧環境條件下，只要24小時即可得到接近的效果。

  鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)測試(shi)(shi)(shi)(shi)主要包(bao)括四(si)種方法(fa)，中(zhong)(zhong)性(xing)(xing)(xing)(xing)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)、銅(tong)(tong)鹽(yan)(yan)(yan)(yan)加(jia)(jia)(jia)(jia)速(su)醋(cu)(cu)(cu)酸(suan)(suan)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)、醋(cu)(cu)(cu)酸(suan)(suan)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)和交變(bian)(bian)(bian)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)。 中(zhong)(zhong)性(xing)(xing)(xing)(xing)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)，又稱NSS試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)，是(shi)目前應用領域最(zui)廣、出現(xian)最(zui)早的(de)(de)(de)(de)一種加(jia)(jia)(jia)(jia)速(su)腐(fu)蝕(shi)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)方法(fa)。一般(ban)采用5%的(de)(de)(de)(de)氯(lv)化(hua)鈉鹽(yan)(yan)(yan)(yan)水(shui)溶(rong)(rong)液(ye)(ye)，將(jiang)溶(rong)(rong)液(ye)(ye)PH值調在(zai)(zai)中(zhong)(zhong)性(xing)(xing)(xing)(xing)范圍(6.5～7.2)，作(zuo)為(wei)噴霧(wu)(wu)(wu)(wu)使(shi)用。試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)溫度(du)控制在(zai)(zai)35℃，鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)的(de)(de)(de)(de)沉降率(lv)應為(wei)1～2ml/80cm/h。 銅(tong)(tong)鹽(yan)(yan)(yan)(yan)加(jia)(jia)(jia)(jia)速(su)醋(cu)(cu)(cu)酸(suan)(suan)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)，又稱CASS試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)，是(shi)近幾年發展起來的(de)(de)(de)(de)一種快速(su)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)腐(fu)蝕(shi)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)。試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)溫度(du)為(wei)50℃，鹽(yan)(yan)(yan)(yan)溶(rong)(rong)液(ye)(ye)中(zhong)(zhong)加(jia)(jia)(jia)(jia)入少量銅(tong)(tong)鹽(yan)(yan)(yan)(yan)-氯(lv)化(hua)銅(tong)(tong)，具(ju)有強烈誘發腐(fu)蝕(shi)能(neng)力，腐(fu)蝕(shi)速(su)度(du)是(shi)NSS試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)的(de)(de)(de)(de)8倍左(zuo)右。 醋(cu)(cu)(cu)酸(suan)(suan)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)，又稱ASS試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)，是(shi)建立在(zai)(zai)中(zhong)(zhong)性(xing)(xing)(xing)(xing)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)的(de)(de)(de)(de)基礎上發展而來的(de)(de)(de)(de)。在(zai)(zai)5%氯(lv)化(hua)鈉溶(rong)(rong)液(ye)(ye)中(zhong)(zhong)加(jia)(jia)(jia)(jia)入冰醋(cu)(cu)(cu)酸(suan)(suan)，將(jiang)溶(rong)(rong)液(ye)(ye)的(de)(de)(de)(de)PH值降為(wei)3左(zuo)右，溶(rong)(rong)液(ye)(ye)變(bian)(bian)(bian)成酸(suan)(suan)性(xing)(xing)(xing)(xing)，最(zui)后形成的(de)(de)(de)(de)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)也由中(zhong)(zhong)性(xing)(xing)(xing)(xing)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)變(bian)(bian)(bian)成酸(suan)(suan)性(xing)(xing)(xing)(xing)。其腐(fu)蝕(shi)速(su)度(du)是(shi)NSS試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)的(de)(de)(de)(de)3倍左(zuo)右。 交變(bian)(bian)(bian)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)則是(shi)屬于綜合鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)，它的(de)(de)(de)(de)原理是(shi)在(zai)(zai)中(zhong)(zhong)性(xing)(xing)(xing)(xing)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)的(de)(de)(de)(de)基礎上加(jia)(jia)(jia)(jia)恒定濕熱的(de)(de)(de)(de)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)。主要用于空腔型(xing)的(de)(de)(de)(de)整(zheng)機產(chan)品，通過潮濕環境的(de)(de)(de)(de)滲(shen)透，使(shi)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)腐(fu)蝕(shi)既在(zai)(zai)產(chan)品表面發生，也在(zai)(zai)產(chan)品內(nei)部發生。交變(bian)(bian)(bian)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)將(jiang)產(chan)品環境在(zai)(zai)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)和濕熱兩種條件下不斷替換，最(zui)后評(ping)估整(zheng)機產(chan)品的(de)(de)(de)(de)電性(xing)(xing)(xing)(xing)能(neng)和機械性(xing)(xing)(xing)(xing)能(neng)的(de)(de)(de)(de)變(bian)(bian)(bian)化(hua)程度(du)。