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(xing)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)(wu)測試(shi)(shi)(shi)(shi)(shi)(shi)(shi)主(zhu)要(yao)包(bao)括(kuo)四種(zhong)方法，中(zhong)性鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)、銅鹽(yan)(yan)(yan)(yan)加速(su)(su)醋(cu)酸(suan)(suan)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)、醋(cu)酸(suan)(suan)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)和(he)交(jiao)變(bian)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)。 中(zhong)性鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)，又(you)稱(cheng)NSS試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)，是(shi)目前應(ying)用領域(yu)最(zui)廣、出現(xian)最(zui)早的(de)一(yi)種(zhong)加速(su)(su)腐(fu)蝕(shi)(shi)(shi)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)方法。一(yi)般采用5%的(de)氯(lv)化(hua)鈉鹽(yan)(yan)(yan)(yan)水溶(rong)液(ye)(ye)，將(jiang)溶(rong)液(ye)(ye)PH值(zhi)調在(zai)(zai)中(zhong)性范圍(6.5～7.2)，作為噴(pen)霧(wu)(wu)(wu)(wu)(wu)使用。試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)溫度(du)控制在(zai)(zai)35℃，鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)的(de)沉(chen)降率應(ying)為1～2ml/80cm/h。 銅鹽(yan)(yan)(yan)(yan)加速(su)(su)醋(cu)酸(suan)(suan)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)，又(you)稱(cheng)CASS試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)，是(shi)近幾年發(fa)展起來(lai)的(de)一(yi)種(zhong)快速(su)(su)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)腐(fu)蝕(shi)(shi)(shi)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)。試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)溫度(du)為50℃，鹽(yan)(yan)(yan)(yan)溶(rong)液(ye)(ye)中(zhong)加入少量銅鹽(yan)(yan)(yan)(yan)-氯(lv)化(hua)銅，具有強烈誘發(fa)腐(fu)蝕(shi)(shi)(shi)能力，腐(fu)蝕(shi)(shi)(shi)速(su)(su)度(du)是(shi)NSS試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)的(de)8倍左(zuo)右(you)。 醋(cu)酸(suan)(suan)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)，又(you)稱(cheng)ASS試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)，是(shi)建立在(zai)(zai)中(zhong)性鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)的(de)基礎上(shang)發(fa)展而來(lai)的(de)。在(zai)(zai)5%氯(lv)化(hua)鈉溶(rong)液(ye)(ye)中(zhong)加入冰醋(cu)酸(suan)(suan)，將(jiang)溶(rong)液(ye)(ye)的(de)PH值(zhi)降為3左(zuo)右(you)，溶(rong)液(ye)(ye)變(bian)成酸(suan)(suan)性，最(zui)后(hou)形成的(de)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)也(ye)由中(zhong)性鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)變(bian)成酸(suan)(suan)性。其腐(fu)蝕(shi)(shi)(shi)速(su)(su)度(du)是(shi)NSS試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)的(de)3倍左(zuo)右(you)。 交(jiao)變(bian)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)則是(shi)屬于(yu)綜合(he)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)，它的(de)原理是(shi)在(zai)(zai)中(zhong)性鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)的(de)基礎上(shang)加恒定濕熱的(de)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)。主(zhu)要(yao)用于(yu)空腔型的(de)整機產(chan)(chan)品(pin)，通(tong)過(guo)潮濕環(huan)境的(de)滲透，使鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)腐(fu)蝕(shi)(shi)(shi)既(ji)在(zai)(zai)產(chan)(chan)品(pin)表面發(fa)生，也(ye)在(zai)(zai)產(chan)(chan)品(pin)內部發(fa)生。交(jiao)變(bian)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)將(jiang)產(chan)(chan)品(pin)環(huan)境在(zai)(zai)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)和(he)濕熱兩種(zhong)條件(jian)下不(bu)斷替換，最(zui)后(hou)評(ping)估整機產(chan)(chan)品(pin)的(de)電性能和(he)機械性能的(de)變(bian)化(hua)程度(du)。