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)霧(wu)(wu)(wu)(wu)(wu)(wu)(wu)測試(shi)(shi)(shi)(shi)(shi)(shi)(shi)主要(yao)包括四(si)種(zhong)方(fang)法(fa)，中(zhong)(zhong)性(xing)(xing)鹽(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)、銅(tong)(tong)鹽(yan)(yan)加(jia)速(su)醋(cu)(cu)酸(suan)(suan)鹽(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)、醋(cu)(cu)酸(suan)(suan)鹽(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)和(he)(he)交(jiao)變(bian)鹽(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)。 中(zhong)(zhong)性(xing)(xing)鹽(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)，又稱(cheng)(cheng)NSS試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)，是(shi)(shi)目前(qian)應用(yong)領域(yu)最廣、出(chu)現最早(zao)的(de)(de)(de)一種(zhong)加(jia)速(su)腐(fu)(fu)(fu)蝕(shi)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)方(fang)法(fa)。一般采用(yong)5%的(de)(de)(de)氯化鈉(na)鹽(yan)(yan)水溶(rong)(rong)液(ye)(ye)(ye)，將溶(rong)(rong)液(ye)(ye)(ye)PH值(zhi)調在(zai)中(zhong)(zhong)性(xing)(xing)范圍(wei)(6.5～7.2)，作(zuo)為(wei)(wei)噴(pen)霧(wu)(wu)(wu)(wu)(wu)(wu)(wu)使(shi)用(yong)。試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)溫度(du)控制在(zai)35℃，鹽(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)(wu)(wu)的(de)(de)(de)沉降率應為(wei)(wei)1～2ml/80cm/h。 銅(tong)(tong)鹽(yan)(yan)加(jia)速(su)醋(cu)(cu)酸(suan)(suan)鹽(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)，又稱(cheng)(cheng)CASS試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)，是(shi)(shi)近幾年(nian)發展起(qi)來的(de)(de)(de)一種(zhong)快速(su)鹽(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)(wu)(wu)腐(fu)(fu)(fu)蝕(shi)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)。試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)溫度(du)為(wei)(wei)50℃，鹽(yan)(yan)溶(rong)(rong)液(ye)(ye)(ye)中(zhong)(zhong)加(jia)入(ru)少量銅(tong)(tong)鹽(yan)(yan)-氯化銅(tong)(tong)，具有強烈(lie)誘發腐(fu)(fu)(fu)蝕(shi)能(neng)力，腐(fu)(fu)(fu)蝕(shi)速(su)度(du)是(shi)(shi)NSS試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)的(de)(de)(de)8倍左(zuo)右(you)。 醋(cu)(cu)酸(suan)(suan)鹽(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)，又稱(cheng)(cheng)ASS試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)，是(shi)(shi)建立在(zai)中(zhong)(zhong)性(xing)(xing)鹽(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)的(de)(de)(de)基礎上發展而來的(de)(de)(de)。在(zai)5%氯化鈉(na)溶(rong)(rong)液(ye)(ye)(ye)中(zhong)(zhong)加(jia)入(ru)冰醋(cu)(cu)酸(suan)(suan)，將溶(rong)(rong)液(ye)(ye)(ye)的(de)(de)(de)PH值(zhi)降為(wei)(wei)3左(zuo)右(you)，溶(rong)(rong)液(ye)(ye)(ye)變(bian)成(cheng)酸(suan)(suan)性(xing)(xing)，最后(hou)形(xing)成(cheng)的(de)(de)(de)鹽(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)(wu)(wu)也由中(zhong)(zhong)性(xing)(xing)鹽(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)(wu)(wu)變(bian)成(cheng)酸(suan)(suan)性(xing)(xing)。其腐(fu)(fu)(fu)蝕(shi)速(su)度(du)是(shi)(shi)NSS試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)的(de)(de)(de)3倍左(zuo)右(you)。 交(jiao)變(bian)鹽(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)則是(shi)(shi)屬于(yu)綜合鹽(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)，它的(de)(de)(de)原理(li)是(shi)(shi)在(zai)中(zhong)(zhong)性(xing)(xing)鹽(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)的(de)(de)(de)基礎上加(jia)恒(heng)定(ding)濕熱(re)的(de)(de)(de)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)。主要(yao)用(yong)于(yu)空腔型(xing)的(de)(de)(de)整(zheng)(zheng)機產(chan)品，通過(guo)潮濕環境(jing)的(de)(de)(de)滲透，使(shi)鹽(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)(wu)(wu)腐(fu)(fu)(fu)蝕(shi)既(ji)在(zai)產(chan)品表面發生(sheng)，也在(zai)產(chan)品內部發生(sheng)。交(jiao)變(bian)鹽(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)將產(chan)品環境(jing)在(zai)鹽(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)(wu)(wu)和(he)(he)濕熱(re)兩種(zhong)條件(jian)下不(bu)斷替換(huan)，最后(hou)評估整(zheng)(zheng)機產(chan)品的(de)(de)(de)電(dian)性(xing)(xing)能(neng)和(he)(he)機械性(xing)(xing)能(neng)的(de)(de)(de)變(bian)化程度(du)。