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(nai)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)霧(wu)(wu)(wu)(wu)(wu)測試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)主要(yao)包(bao)括四種(zhong)方法(fa)，中(zhong)(zhong)性(xing)(xing)(xing)(xing)(xing)鹽(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)、銅(tong)鹽(yan)加(jia)速醋(cu)酸鹽(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)、醋(cu)酸鹽(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)和交(jiao)變(bian)(bian)鹽(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)。 中(zhong)(zhong)性(xing)(xing)(xing)(xing)(xing)鹽(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)，又稱(cheng)NSS試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)，是(shi)目前應用(yong)(yong)領(ling)域(yu)最(zui)廣、出(chu)現最(zui)早的(de)(de)(de)(de)(de)一種(zhong)加(jia)速腐(fu)(fu)蝕試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)方法(fa)。一般采用(yong)(yong)5%的(de)(de)(de)(de)(de)氯(lv)化(hua)鈉鹽(yan)水溶(rong)(rong)(rong)液(ye)，將(jiang)溶(rong)(rong)(rong)液(ye)PH值(zhi)(zhi)調在(zai)(zai)中(zhong)(zhong)性(xing)(xing)(xing)(xing)(xing)范圍(6.5～7.2)，作為(wei)噴霧(wu)(wu)(wu)(wu)(wu)使(shi)用(yong)(yong)。試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)溫度(du)(du)(du)控制在(zai)(zai)35℃，鹽(yan)霧(wu)(wu)(wu)(wu)(wu)的(de)(de)(de)(de)(de)沉降率應為(wei)1～2ml/80cm/h。 銅(tong)鹽(yan)加(jia)速醋(cu)酸鹽(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)，又稱(cheng)CASS試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)，是(shi)近幾年(nian)發(fa)展起來的(de)(de)(de)(de)(de)一種(zhong)快速鹽(yan)霧(wu)(wu)(wu)(wu)(wu)腐(fu)(fu)蝕試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)。試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)溫度(du)(du)(du)為(wei)50℃，鹽(yan)溶(rong)(rong)(rong)液(ye)中(zhong)(zhong)加(jia)入(ru)少量銅(tong)鹽(yan)-氯(lv)化(hua)銅(tong)，具(ju)有強烈(lie)誘發(fa)腐(fu)(fu)蝕能力，腐(fu)(fu)蝕速度(du)(du)(du)是(shi)NSS試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)的(de)(de)(de)(de)(de)8倍(bei)左(zuo)右。 醋(cu)酸鹽(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)，又稱(cheng)ASS試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)，是(shi)建立(li)在(zai)(zai)中(zhong)(zhong)性(xing)(xing)(xing)(xing)(xing)鹽(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)的(de)(de)(de)(de)(de)基礎上發(fa)展而來的(de)(de)(de)(de)(de)。在(zai)(zai)5%氯(lv)化(hua)鈉溶(rong)(rong)(rong)液(ye)中(zhong)(zhong)加(jia)入(ru)冰醋(cu)酸，將(jiang)溶(rong)(rong)(rong)液(ye)的(de)(de)(de)(de)(de)PH值(zhi)(zhi)降為(wei)3左(zuo)右，溶(rong)(rong)(rong)液(ye)變(bian)(bian)成(cheng)酸性(xing)(xing)(xing)(xing)(xing)，最(zui)后形成(cheng)的(de)(de)(de)(de)(de)鹽(yan)霧(wu)(wu)(wu)(wu)(wu)也由中(zhong)(zhong)性(xing)(xing)(xing)(xing)(xing)鹽(yan)霧(wu)(wu)(wu)(wu)(wu)變(bian)(bian)成(cheng)酸性(xing)(xing)(xing)(xing)(xing)。其腐(fu)(fu)蝕速度(du)(du)(du)是(shi)NSS試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)的(de)(de)(de)(de)(de)3倍(bei)左(zuo)右。 交(jiao)變(bian)(bian)鹽(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)則(ze)是(shi)屬于綜合(he)鹽(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)，它的(de)(de)(de)(de)(de)原理(li)是(shi)在(zai)(zai)中(zhong)(zhong)性(xing)(xing)(xing)(xing)(xing)鹽(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)的(de)(de)(de)(de)(de)基礎上加(jia)恒定(ding)濕(shi)熱的(de)(de)(de)(de)(de)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)。主要(yao)用(yong)(yong)于空腔型(xing)的(de)(de)(de)(de)(de)整(zheng)機(ji)產(chan)品(pin)，通過潮濕(shi)環境的(de)(de)(de)(de)(de)滲透(tou)，使(shi)鹽(yan)霧(wu)(wu)(wu)(wu)(wu)腐(fu)(fu)蝕既在(zai)(zai)產(chan)品(pin)表面發(fa)生(sheng)，也在(zai)(zai)產(chan)品(pin)內部發(fa)生(sheng)。交(jiao)變(bian)(bian)鹽(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)將(jiang)產(chan)品(pin)環境在(zai)(zai)鹽(yan)霧(wu)(wu)(wu)(wu)(wu)和濕(shi)熱兩種(zhong)條(tiao)件(jian)下不斷(duan)替換，最(zui)后評估整(zheng)機(ji)產(chan)品(pin)的(de)(de)(de)(de)(de)電性(xing)(xing)(xing)(xing)(xing)能和機(ji)械性(xing)(xing)(xing)(xing)(xing)能的(de)(de)(de)(de)(de)變(bian)(bian)化(hua)程度(du)(du)(du)。