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)霧(wu)(wu)測試(shi)(shi)(shi)(shi)(shi)(shi)主(zhu)要包括四(si)種(zhong)方法(fa)，中(zhong)(zhong)(zhong)性(xing)(xing)(xing)鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)、銅(tong)鹽(yan)(yan)(yan)(yan)(yan)加(jia)(jia)速(su)(su)醋(cu)酸(suan)鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)、醋(cu)酸(suan)鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)和(he)交(jiao)(jiao)變(bian)(bian)鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)。 中(zhong)(zhong)(zhong)性(xing)(xing)(xing)鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)，又稱(cheng)NSS試(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)，是(shi)目前應用(yong)領域最廣、出(chu)現最早的(de)(de)(de)一種(zhong)加(jia)(jia)速(su)(su)腐(fu)蝕(shi)試(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)方法(fa)。一般采用(yong)5%的(de)(de)(de)氯(lv)(lv)化鈉(na)鹽(yan)(yan)(yan)(yan)(yan)水溶(rong)液(ye)，將溶(rong)液(ye)PH值(zhi)調(diao)在(zai)(zai)(zai)中(zhong)(zhong)(zhong)性(xing)(xing)(xing)范圍(6.5～7.2)，作為噴霧(wu)(wu)使用(yong)。試(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)溫度控制在(zai)(zai)(zai)35℃，鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)的(de)(de)(de)沉(chen)降(jiang)率應為1～2ml/80cm/h。 銅(tong)鹽(yan)(yan)(yan)(yan)(yan)加(jia)(jia)速(su)(su)醋(cu)酸(suan)鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)，又稱(cheng)CASS試(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)，是(shi)近幾年發(fa)展起來的(de)(de)(de)一種(zhong)快速(su)(su)鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)腐(fu)蝕(shi)試(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)。試(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)溫度為50℃，鹽(yan)(yan)(yan)(yan)(yan)溶(rong)液(ye)中(zhong)(zhong)(zhong)加(jia)(jia)入少量銅(tong)鹽(yan)(yan)(yan)(yan)(yan)-氯(lv)(lv)化銅(tong)，具(ju)有強烈誘發(fa)腐(fu)蝕(shi)能力，腐(fu)蝕(shi)速(su)(su)度是(shi)NSS試(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)的(de)(de)(de)8倍左(zuo)右。 醋(cu)酸(suan)鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)，又稱(cheng)ASS試(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)，是(shi)建(jian)立(li)在(zai)(zai)(zai)中(zhong)(zhong)(zhong)性(xing)(xing)(xing)鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)的(de)(de)(de)基礎上(shang)發(fa)展而(er)來的(de)(de)(de)。在(zai)(zai)(zai)5%氯(lv)(lv)化鈉(na)溶(rong)液(ye)中(zhong)(zhong)(zhong)加(jia)(jia)入冰(bing)醋(cu)酸(suan)，將溶(rong)液(ye)的(de)(de)(de)PH值(zhi)降(jiang)為3左(zuo)右，溶(rong)液(ye)變(bian)(bian)成酸(suan)性(xing)(xing)(xing)，最后形(xing)成的(de)(de)(de)鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)也由(you)中(zhong)(zhong)(zhong)性(xing)(xing)(xing)鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)變(bian)(bian)成酸(suan)性(xing)(xing)(xing)。其腐(fu)蝕(shi)速(su)(su)度是(shi)NSS試(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)的(de)(de)(de)3倍左(zuo)右。 交(jiao)(jiao)變(bian)(bian)鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)則是(shi)屬(shu)于綜(zong)合鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)，它(ta)的(de)(de)(de)原理是(shi)在(zai)(zai)(zai)中(zhong)(zhong)(zhong)性(xing)(xing)(xing)鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)的(de)(de)(de)基礎上(shang)加(jia)(jia)恒定濕(shi)熱(re)的(de)(de)(de)試(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)。主(zhu)要用(yong)于空腔型的(de)(de)(de)整機產(chan)品(pin)(pin)(pin)，通過潮(chao)濕(shi)環境的(de)(de)(de)滲透，使鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)腐(fu)蝕(shi)既在(zai)(zai)(zai)產(chan)品(pin)(pin)(pin)表面發(fa)生(sheng)，也在(zai)(zai)(zai)產(chan)品(pin)(pin)(pin)內部發(fa)生(sheng)。交(jiao)(jiao)變(bian)(bian)鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)將產(chan)品(pin)(pin)(pin)環境在(zai)(zai)(zai)鹽(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)和(he)濕(shi)熱(re)兩種(zhong)條件下不(bu)斷替換，最后評估整機產(chan)品(pin)(pin)(pin)的(de)(de)(de)電(dian)性(xing)(xing)(xing)能和(he)機械性(xing)(xing)(xing)能的(de)(de)(de)變(bian)(bian)化程度。