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(neng)，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)(yan)(yan)霧(wu)(wu)(wu)測試(shi)(shi)主要包括四種方(fang)法(fa)，中(zhong)(zhong)(zhong)(zhong)性鹽(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)試(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)、銅(tong)鹽(yan)(yan)(yan)(yan)(yan)(yan)加速醋(cu)(cu)酸(suan)(suan)(suan)鹽(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)試(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)、醋(cu)(cu)酸(suan)(suan)(suan)鹽(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)試(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)和(he)交變(bian)鹽(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)試(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)。 中(zhong)(zhong)(zhong)(zhong)性鹽(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)試(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)，又稱NSS試(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)，是目前應用(yong)領域(yu)最(zui)廣、出(chu)現最(zui)早的(de)(de)(de)一種加速腐(fu)蝕試(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)方(fang)法(fa)。一般采用(yong)5%的(de)(de)(de)氯化鈉鹽(yan)(yan)(yan)(yan)(yan)(yan)水溶(rong)液(ye)，將(jiang)溶(rong)液(ye)PH值(zhi)(zhi)調在(zai)(zai)(zai)中(zhong)(zhong)(zhong)(zhong)性范圍(wei)(6.5～7.2)，作為噴霧(wu)(wu)(wu)使(shi)用(yong)。試(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)溫(wen)度(du)(du)控制在(zai)(zai)(zai)35℃，鹽(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)的(de)(de)(de)沉(chen)降率(lv)應為1～2ml/80cm/h。 銅(tong)鹽(yan)(yan)(yan)(yan)(yan)(yan)加速醋(cu)(cu)酸(suan)(suan)(suan)鹽(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)試(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)，又稱CASS試(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)，是近幾年發(fa)展起(qi)來的(de)(de)(de)一種快(kuai)速鹽(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)腐(fu)蝕試(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)。試(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)溫(wen)度(du)(du)為50℃，鹽(yan)(yan)(yan)(yan)(yan)(yan)溶(rong)液(ye)中(zhong)(zhong)(zhong)(zhong)加入少量銅(tong)鹽(yan)(yan)(yan)(yan)(yan)(yan)-氯化銅(tong)，具有強烈誘發(fa)腐(fu)蝕能(neng)(neng)力，腐(fu)蝕速度(du)(du)是NSS試(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)的(de)(de)(de)8倍左右(you)。 醋(cu)(cu)酸(suan)(suan)(suan)鹽(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)試(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)，又稱ASS試(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)，是建立在(zai)(zai)(zai)中(zhong)(zhong)(zhong)(zhong)性鹽(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)試(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)的(de)(de)(de)基(ji)礎上發(fa)展而來的(de)(de)(de)。在(zai)(zai)(zai)5%氯化鈉溶(rong)液(ye)中(zhong)(zhong)(zhong)(zhong)加入冰醋(cu)(cu)酸(suan)(suan)(suan)，將(jiang)溶(rong)液(ye)的(de)(de)(de)PH值(zhi)(zhi)降為3左右(you)，溶(rong)液(ye)變(bian)成酸(suan)(suan)(suan)性，最(zui)后形成的(de)(de)(de)鹽(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)也由中(zhong)(zhong)(zhong)(zhong)性鹽(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)變(bian)成酸(suan)(suan)(suan)性。其(qi)腐(fu)蝕速度(du)(du)是NSS試(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)的(de)(de)(de)3倍左右(you)。 交變(bian)鹽(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)試(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)則是屬(shu)于(yu)綜合鹽(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)試(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)，它的(de)(de)(de)原理是在(zai)(zai)(zai)中(zhong)(zhong)(zhong)(zhong)性鹽(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)試(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)的(de)(de)(de)基(ji)礎上加恒定濕(shi)熱(re)(re)的(de)(de)(de)試(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)。主要用(yong)于(yu)空腔(qiang)型的(de)(de)(de)整(zheng)機(ji)產(chan)(chan)品(pin)，通過潮濕(shi)環境的(de)(de)(de)滲透，使(shi)鹽(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)腐(fu)蝕既(ji)在(zai)(zai)(zai)產(chan)(chan)品(pin)表面發(fa)生，也在(zai)(zai)(zai)產(chan)(chan)品(pin)內(nei)部(bu)發(fa)生。交變(bian)鹽(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)試(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)將(jiang)產(chan)(chan)品(pin)環境在(zai)(zai)(zai)鹽(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)和(he)濕(shi)熱(re)(re)兩種條件(jian)下(xia)不(bu)斷替換，最(zui)后評估(gu)整(zheng)機(ji)產(chan)(chan)品(pin)的(de)(de)(de)電性能(neng)(neng)和(he)機(ji)械性能(neng)(neng)的(de)(de)(de)變(bian)化程度(du)(du)。