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)霧(wu)(wu)測試(shi)(shi)(shi)主要包括四種(zhong)(zhong)(zhong)方法(fa)，中(zhong)(zhong)(zhong)(zhong)性鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)、銅(tong)鹽(yan)(yan)(yan)(yan)(yan)加(jia)速(su)醋(cu)酸(suan)鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)、醋(cu)酸(suan)鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)和(he)(he)交(jiao)變(bian)(bian)鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)。 中(zhong)(zhong)(zhong)(zhong)性鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)，又(you)稱NSS試(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)，是(shi)(shi)目前應(ying)用(yong)領域最廣、出現(xian)最早的(de)(de)一種(zhong)(zhong)(zhong)加(jia)速(su)腐蝕(shi)試(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)方法(fa)。一般采用(yong)5%的(de)(de)氯化鈉鹽(yan)(yan)(yan)(yan)(yan)水溶(rong)(rong)(rong)液，將溶(rong)(rong)(rong)液PH值調在(zai)(zai)中(zhong)(zhong)(zhong)(zhong)性范圍(6.5～7.2)，作(zuo)為噴霧(wu)(wu)使用(yong)。試(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)溫(wen)(wen)度(du)(du)控(kong)制在(zai)(zai)35℃，鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)的(de)(de)沉降(jiang)率應(ying)為1～2ml/80cm/h。 銅(tong)鹽(yan)(yan)(yan)(yan)(yan)加(jia)速(su)醋(cu)酸(suan)鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)，又(you)稱CASS試(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)，是(shi)(shi)近幾年發(fa)(fa)展起來(lai)的(de)(de)一種(zhong)(zhong)(zhong)快速(su)鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)腐蝕(shi)試(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)。試(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)溫(wen)(wen)度(du)(du)為50℃，鹽(yan)(yan)(yan)(yan)(yan)溶(rong)(rong)(rong)液中(zhong)(zhong)(zhong)(zhong)加(jia)入少(shao)量銅(tong)鹽(yan)(yan)(yan)(yan)(yan)-氯化銅(tong)，具有強烈誘發(fa)(fa)腐蝕(shi)能力(li)，腐蝕(shi)速(su)度(du)(du)是(shi)(shi)NSS試(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)的(de)(de)8倍左(zuo)右。 醋(cu)酸(suan)鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)，又(you)稱ASS試(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)，是(shi)(shi)建立在(zai)(zai)中(zhong)(zhong)(zhong)(zhong)性鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)的(de)(de)基礎(chu)上發(fa)(fa)展而來(lai)的(de)(de)。在(zai)(zai)5%氯化鈉溶(rong)(rong)(rong)液中(zhong)(zhong)(zhong)(zhong)加(jia)入冰醋(cu)酸(suan)，將溶(rong)(rong)(rong)液的(de)(de)PH值降(jiang)為3左(zuo)右，溶(rong)(rong)(rong)液變(bian)(bian)成(cheng)酸(suan)性，最后(hou)形成(cheng)的(de)(de)鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)也由中(zhong)(zhong)(zhong)(zhong)性鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)變(bian)(bian)成(cheng)酸(suan)性。其(qi)腐蝕(shi)速(su)度(du)(du)是(shi)(shi)NSS試(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)的(de)(de)3倍左(zuo)右。 交(jiao)變(bian)(bian)鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)則(ze)是(shi)(shi)屬于(yu)綜(zong)合鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)，它(ta)的(de)(de)原理是(shi)(shi)在(zai)(zai)中(zhong)(zhong)(zhong)(zhong)性鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)的(de)(de)基礎(chu)上加(jia)恒(heng)定濕(shi)(shi)熱(re)的(de)(de)試(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)。主要用(yong)于(yu)空腔型的(de)(de)整機(ji)產(chan)(chan)品(pin)，通過潮濕(shi)(shi)環境的(de)(de)滲透，使鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)腐蝕(shi)既在(zai)(zai)產(chan)(chan)品(pin)表(biao)面(mian)發(fa)(fa)生，也在(zai)(zai)產(chan)(chan)品(pin)內(nei)部發(fa)(fa)生。交(jiao)變(bian)(bian)鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)將產(chan)(chan)品(pin)環境在(zai)(zai)鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)和(he)(he)濕(shi)(shi)熱(re)兩種(zhong)(zhong)(zhong)條件(jian)下不斷(duan)替(ti)換，最后(hou)評估整機(ji)產(chan)(chan)品(pin)的(de)(de)電性能和(he)(he)機(ji)械性能的(de)(de)變(bian)(bian)化程度(du)(du)。