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(nai)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)霧(wu)測試(shi)(shi)(shi)(shi)主要(yao)包括四(si)種方(fang)法，中(zhong)(zhong)性(xing)(xing)(xing)(xing)(xing)鹽(yan)(yan)(yan)(yan)霧(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)、銅(tong)(tong)(tong)鹽(yan)(yan)(yan)(yan)加速(su)醋(cu)(cu)酸(suan)鹽(yan)(yan)(yan)(yan)霧(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)、醋(cu)(cu)酸(suan)鹽(yan)(yan)(yan)(yan)霧(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)和(he)交(jiao)變(bian)鹽(yan)(yan)(yan)(yan)霧(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)。 中(zhong)(zhong)性(xing)(xing)(xing)(xing)(xing)鹽(yan)(yan)(yan)(yan)霧(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)，又稱NSS試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)，是目前應用領(ling)域(yu)最(zui)(zui)廣(guang)、出現最(zui)(zui)早的(de)(de)(de)(de)(de)一(yi)種加速(su)腐蝕試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)方(fang)法。一(yi)般采用5%的(de)(de)(de)(de)(de)氯化鈉鹽(yan)(yan)(yan)(yan)水溶液(ye)，將(jiang)溶液(ye)PH值調在中(zhong)(zhong)性(xing)(xing)(xing)(xing)(xing)范圍(6.5～7.2)，作為噴霧(wu)使(shi)用。試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)溫(wen)度控制(zhi)在35℃，鹽(yan)(yan)(yan)(yan)霧(wu)的(de)(de)(de)(de)(de)沉降(jiang)率應為1～2ml/80cm/h。 銅(tong)(tong)(tong)鹽(yan)(yan)(yan)(yan)加速(su)醋(cu)(cu)酸(suan)鹽(yan)(yan)(yan)(yan)霧(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)，又稱CASS試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)，是近幾年發(fa)展起(qi)來(lai)的(de)(de)(de)(de)(de)一(yi)種快速(su)鹽(yan)(yan)(yan)(yan)霧(wu)腐蝕試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)。試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)溫(wen)度為50℃，鹽(yan)(yan)(yan)(yan)溶液(ye)中(zhong)(zhong)加入(ru)少(shao)量銅(tong)(tong)(tong)鹽(yan)(yan)(yan)(yan)-氯化銅(tong)(tong)(tong)，具有(you)強烈誘發(fa)腐蝕能力(li)，腐蝕速(su)度是NSS試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)的(de)(de)(de)(de)(de)8倍左右。 醋(cu)(cu)酸(suan)鹽(yan)(yan)(yan)(yan)霧(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)，又稱ASS試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)，是建立在中(zhong)(zhong)性(xing)(xing)(xing)(xing)(xing)鹽(yan)(yan)(yan)(yan)霧(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)的(de)(de)(de)(de)(de)基礎(chu)上發(fa)展而來(lai)的(de)(de)(de)(de)(de)。在5%氯化鈉溶液(ye)中(zhong)(zhong)加入(ru)冰(bing)醋(cu)(cu)酸(suan)，將(jiang)溶液(ye)的(de)(de)(de)(de)(de)PH值降(jiang)為3左右，溶液(ye)變(bian)成(cheng)酸(suan)性(xing)(xing)(xing)(xing)(xing)，最(zui)(zui)后形成(cheng)的(de)(de)(de)(de)(de)鹽(yan)(yan)(yan)(yan)霧(wu)也(ye)(ye)由(you)中(zhong)(zhong)性(xing)(xing)(xing)(xing)(xing)鹽(yan)(yan)(yan)(yan)霧(wu)變(bian)成(cheng)酸(suan)性(xing)(xing)(xing)(xing)(xing)。其腐蝕速(su)度是NSS試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)的(de)(de)(de)(de)(de)3倍左右。 交(jiao)變(bian)鹽(yan)(yan)(yan)(yan)霧(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)則(ze)是屬于(yu)綜合鹽(yan)(yan)(yan)(yan)霧(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)，它的(de)(de)(de)(de)(de)原理是在中(zhong)(zhong)性(xing)(xing)(xing)(xing)(xing)鹽(yan)(yan)(yan)(yan)霧(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)的(de)(de)(de)(de)(de)基礎(chu)上加恒定(ding)濕熱(re)(re)的(de)(de)(de)(de)(de)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)。主要(yao)用于(yu)空(kong)腔型(xing)的(de)(de)(de)(de)(de)整機(ji)產(chan)品(pin)(pin)，通過潮濕環境(jing)的(de)(de)(de)(de)(de)滲(shen)透(tou)，使(shi)鹽(yan)(yan)(yan)(yan)霧(wu)腐蝕既(ji)在產(chan)品(pin)(pin)表面發(fa)生，也(ye)(ye)在產(chan)品(pin)(pin)內(nei)部(bu)發(fa)生。交(jiao)變(bian)鹽(yan)(yan)(yan)(yan)霧(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)將(jiang)產(chan)品(pin)(pin)環境(jing)在鹽(yan)(yan)(yan)(yan)霧(wu)和(he)濕熱(re)(re)兩種條件下不斷替換，最(zui)(zui)后評估整機(ji)產(chan)品(pin)(pin)的(de)(de)(de)(de)(de)電性(xing)(xing)(xing)(xing)(xing)能和(he)機(ji)械性(xing)(xing)(xing)(xing)(xing)能的(de)(de)(de)(de)(de)變(bian)化程度。