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)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)測試(shi)(shi)(shi)(shi)(shi)主要包括四種方法，中(zhong)性(xing)(xing)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)、銅(tong)(tong)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)加(jia)(jia)(jia)速(su)(su)醋(cu)酸鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)、醋(cu)酸鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)和(he)(he)交(jiao)變(bian)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)。 中(zhong)性(xing)(xing)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)，又(you)稱NSS試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)，是(shi)(shi)目前應(ying)用領域最(zui)(zui)(zui)廣、出現最(zui)(zui)(zui)早的(de)(de)(de)(de)(de)一(yi)種加(jia)(jia)(jia)速(su)(su)腐(fu)(fu)蝕(shi)試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)方法。一(yi)般采用5%的(de)(de)(de)(de)(de)氯化(hua)鈉鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)水(shui)溶(rong)液(ye)，將溶(rong)液(ye)PH值(zhi)調在(zai)(zai)中(zhong)性(xing)(xing)范(fan)圍(wei)(6.5～7.2)，作為(wei)噴霧(wu)(wu)(wu)(wu)(wu)使用。試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)溫度控制(zhi)在(zai)(zai)35℃，鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)的(de)(de)(de)(de)(de)沉降率應(ying)為(wei)1～2ml/80cm/h。 銅(tong)(tong)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)加(jia)(jia)(jia)速(su)(su)醋(cu)酸鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)，又(you)稱CASS試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)，是(shi)(shi)近幾年(nian)發(fa)展起來的(de)(de)(de)(de)(de)一(yi)種快速(su)(su)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)腐(fu)(fu)蝕(shi)試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)。試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)溫度為(wei)50℃，鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)溶(rong)液(ye)中(zhong)加(jia)(jia)(jia)入(ru)少量銅(tong)(tong)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)-氯化(hua)銅(tong)(tong)，具有(you)強(qiang)烈誘發(fa)腐(fu)(fu)蝕(shi)能力，腐(fu)(fu)蝕(shi)速(su)(su)度是(shi)(shi)NSS試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)的(de)(de)(de)(de)(de)8倍左右。 醋(cu)酸鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)，又(you)稱ASS試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)，是(shi)(shi)建立在(zai)(zai)中(zhong)性(xing)(xing)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)的(de)(de)(de)(de)(de)基礎上發(fa)展而來的(de)(de)(de)(de)(de)。在(zai)(zai)5%氯化(hua)鈉溶(rong)液(ye)中(zhong)加(jia)(jia)(jia)入(ru)冰醋(cu)酸，將溶(rong)液(ye)的(de)(de)(de)(de)(de)PH值(zhi)降為(wei)3左右，溶(rong)液(ye)變(bian)成酸性(xing)(xing)，最(zui)(zui)(zui)后形成的(de)(de)(de)(de)(de)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)也由中(zhong)性(xing)(xing)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)變(bian)成酸性(xing)(xing)。其腐(fu)(fu)蝕(shi)速(su)(su)度是(shi)(shi)NSS試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)的(de)(de)(de)(de)(de)3倍左右。 交(jiao)變(bian)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)則是(shi)(shi)屬于(yu)綜合鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)，它(ta)的(de)(de)(de)(de)(de)原理是(shi)(shi)在(zai)(zai)中(zhong)性(xing)(xing)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)的(de)(de)(de)(de)(de)基礎上加(jia)(jia)(jia)恒定濕熱的(de)(de)(de)(de)(de)試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)。主要用于(yu)空腔型的(de)(de)(de)(de)(de)整機產(chan)(chan)品(pin)(pin)，通過潮濕環境的(de)(de)(de)(de)(de)滲透，使鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)腐(fu)(fu)蝕(shi)既(ji)在(zai)(zai)產(chan)(chan)品(pin)(pin)表面發(fa)生(sheng)，也在(zai)(zai)產(chan)(chan)品(pin)(pin)內部(bu)發(fa)生(sheng)。交(jiao)變(bian)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)將產(chan)(chan)品(pin)(pin)環境在(zai)(zai)鹽(yan)(yan)(yan)(yan)(yan)(yan)(yan)(yan)霧(wu)(wu)(wu)(wu)(wu)和(he)(he)濕熱兩種條件下不斷替換，最(zui)(zui)(zui)后評估(gu)整機產(chan)(chan)品(pin)(pin)的(de)(de)(de)(de)(de)電性(xing)(xing)能和(he)(he)機械性(xing)(xing)能的(de)(de)(de)(de)(de)變(bian)化(hua)程(cheng)度。