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)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)測試(shi)主要包括四種方法，中(zhong)性(xing)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)試(shi)驗(yan)(yan)、銅鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)加(jia)(jia)速(su)醋(cu)(cu)酸(suan)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)試(shi)驗(yan)(yan)、醋(cu)(cu)酸(suan)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)試(shi)驗(yan)(yan)和(he)交(jiao)變(bian)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)試(shi)驗(yan)(yan)。 中(zhong)性(xing)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)試(shi)驗(yan)(yan)，又稱(cheng)NSS試(shi)驗(yan)(yan)，是(shi)(shi)(shi)(shi)目前應用領域最廣、出現最早的(de)(de)(de)(de)一(yi)(yi)種加(jia)(jia)速(su)腐(fu)(fu)蝕(shi)(shi)(shi)試(shi)驗(yan)(yan)方法。一(yi)(yi)般采用5%的(de)(de)(de)(de)氯化鈉(na)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)水溶液，將(jiang)(jiang)溶液PH值(zhi)調在(zai)(zai)中(zhong)性(xing)范(fan)圍(wei)(6.5～7.2)，作為噴霧(wu)(wu)(wu)(wu)使(shi)用。試(shi)驗(yan)(yan)溫度(du)(du)控制在(zai)(zai)35℃，鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)的(de)(de)(de)(de)沉(chen)降(jiang)率應為1～2ml/80cm/h。 銅鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)加(jia)(jia)速(su)醋(cu)(cu)酸(suan)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)試(shi)驗(yan)(yan)，又稱(cheng)CASS試(shi)驗(yan)(yan)，是(shi)(shi)(shi)(shi)近幾年發展起來的(de)(de)(de)(de)一(yi)(yi)種快速(su)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)腐(fu)(fu)蝕(shi)(shi)(shi)試(shi)驗(yan)(yan)。試(shi)驗(yan)(yan)溫度(du)(du)為50℃，鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)溶液中(zhong)加(jia)(jia)入少量銅鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)-氯化銅，具有(you)強烈誘發腐(fu)(fu)蝕(shi)(shi)(shi)能(neng)力，腐(fu)(fu)蝕(shi)(shi)(shi)速(su)度(du)(du)是(shi)(shi)(shi)(shi)NSS試(shi)驗(yan)(yan)的(de)(de)(de)(de)8倍(bei)左(zuo)右(you)(you)。 醋(cu)(cu)酸(suan)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)試(shi)驗(yan)(yan)，又稱(cheng)ASS試(shi)驗(yan)(yan)，是(shi)(shi)(shi)(shi)建立在(zai)(zai)中(zhong)性(xing)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)試(shi)驗(yan)(yan)的(de)(de)(de)(de)基(ji)礎(chu)(chu)上發展而來的(de)(de)(de)(de)。在(zai)(zai)5%氯化鈉(na)溶液中(zhong)加(jia)(jia)入冰醋(cu)(cu)酸(suan)，將(jiang)(jiang)溶液的(de)(de)(de)(de)PH值(zhi)降(jiang)為3左(zuo)右(you)(you)，溶液變(bian)成(cheng)酸(suan)性(xing)，最后形成(cheng)的(de)(de)(de)(de)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)也(ye)由(you)中(zhong)性(xing)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)變(bian)成(cheng)酸(suan)性(xing)。其腐(fu)(fu)蝕(shi)(shi)(shi)速(su)度(du)(du)是(shi)(shi)(shi)(shi)NSS試(shi)驗(yan)(yan)的(de)(de)(de)(de)3倍(bei)左(zuo)右(you)(you)。 交(jiao)變(bian)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)試(shi)驗(yan)(yan)則(ze)是(shi)(shi)(shi)(shi)屬于綜合鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)試(shi)驗(yan)(yan)，它的(de)(de)(de)(de)原理是(shi)(shi)(shi)(shi)在(zai)(zai)中(zhong)性(xing)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)試(shi)驗(yan)(yan)的(de)(de)(de)(de)基(ji)礎(chu)(chu)上加(jia)(jia)恒定濕(shi)熱的(de)(de)(de)(de)試(shi)驗(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(shi)環(huan)境(jing)的(de)(de)(de)(de)滲透，使(shi)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)腐(fu)(fu)蝕(shi)(shi)(shi)既在(zai)(zai)產(chan)品表面發生，也(ye)在(zai)(zai)產(chan)品內部發生。交(jiao)變(bian)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)試(shi)驗(yan)(yan)將(jiang)(jiang)產(chan)品環(huan)境(jing)在(zai)(zai)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)和(he)濕(shi)熱兩種條件下不斷(duan)替換(huan)，最后評估整(zheng)機產(chan)品的(de)(de)(de)(de)電性(xing)能(neng)和(he)機械性(xing)能(neng)的(de)(de)(de)(de)變(bian)化程度(du)(du)。