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)測試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)主要包括四種(zhong)方(fang)法(fa)，中(zhong)(zhong)性(xing)(xing)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)、銅鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)加速(su)醋(cu)酸(suan)(suan)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)、醋(cu)酸(suan)(suan)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)和交變(bian)(bian)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)。 中(zhong)(zhong)性(xing)(xing)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)，又稱(cheng)(cheng)NSS試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)，是(shi)目前(qian)應(ying)用(yong)領域最廣、出現最早的(de)一(yi)(yi)(yi)種(zhong)加速(su)腐蝕(shi)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)方(fang)法(fa)。一(yi)(yi)(yi)般采用(yong)5%的(de)氯(lv)化(hua)鈉(na)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)水溶(rong)(rong)液(ye)，將(jiang)溶(rong)(rong)液(ye)PH值調(diao)在中(zhong)(zhong)性(xing)(xing)范圍(6.5～7.2)，作為(wei)噴(pen)霧(wu)(wu)(wu)使(shi)用(yong)。試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)溫(wen)度(du)控(kong)制在35℃，鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)的(de)沉(chen)降(jiang)率應(ying)為(wei)1～2ml/80cm/h。 銅鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)加速(su)醋(cu)酸(suan)(suan)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)，又稱(cheng)(cheng)CASS試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)，是(shi)近幾年發展起來的(de)一(yi)(yi)(yi)種(zhong)快速(su)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)腐蝕(shi)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)。試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)溫(wen)度(du)為(wei)50℃，鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)溶(rong)(rong)液(ye)中(zhong)(zhong)加入少量銅鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)-氯(lv)化(hua)銅，具有強烈誘發腐蝕(shi)能(neng)力，腐蝕(shi)速(su)度(du)是(shi)NSS試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)的(de)8倍(bei)(bei)左(zuo)右(you)。 醋(cu)酸(suan)(suan)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)，又稱(cheng)(cheng)ASS試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)，是(shi)建立在中(zhong)(zhong)性(xing)(xing)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)的(de)基(ji)礎上發展而(er)來的(de)。在5%氯(lv)化(hua)鈉(na)溶(rong)(rong)液(ye)中(zhong)(zhong)加入冰醋(cu)酸(suan)(suan)，將(jiang)溶(rong)(rong)液(ye)的(de)PH值降(jiang)為(wei)3左(zuo)右(you)，溶(rong)(rong)液(ye)變(bian)(bian)成(cheng)酸(suan)(suan)性(xing)(xing)，最后(hou)形成(cheng)的(de)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)也(ye)由中(zhong)(zhong)性(xing)(xing)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)變(bian)(bian)成(cheng)酸(suan)(suan)性(xing)(xing)。其腐蝕(shi)速(su)度(du)是(shi)NSS試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)的(de)3倍(bei)(bei)左(zuo)右(you)。 交變(bian)(bian)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)則是(shi)屬于(yu)綜合鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)，它的(de)原理是(shi)在中(zhong)(zhong)性(xing)(xing)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)的(de)基(ji)礎上加恒定濕熱(re)的(de)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)。主要用(yong)于(yu)空(kong)腔型的(de)整(zheng)機(ji)產(chan)(chan)品(pin)，通過潮濕環境的(de)滲(shen)透，使(shi)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)腐蝕(shi)既在產(chan)(chan)品(pin)表面發生，也(ye)在產(chan)(chan)品(pin)內(nei)部發生。交變(bian)(bian)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)將(jiang)產(chan)(chan)品(pin)環境在鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)和濕熱(re)兩種(zhong)條件下(xia)不斷替換，最后(hou)評估整(zheng)機(ji)產(chan)(chan)品(pin)的(de)電性(xing)(xing)能(neng)和機(ji)械(xie)性(xing)(xing)能(neng)的(de)變(bian)(bian)化(hua)程度(du)。