鹽霧試驗簡述:
鹽霧試驗是一種主要利用鹽霧試驗設備所(suo)創(chuang)造的(de)(de)人工模(mo)(mo)(mo)擬鹽(yan)(yan)(yan)(yan)霧(wu)(wu)環(huan)境(jing)(jing)(jing)條(tiao)件來(lai)考(kao)核(he)產品或(huo)金(jin)屬材料(liao)耐腐(fu)蝕性能的(de)(de)環(huan)境(jing)(jing)(jing)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)。它分為(wei)二大類(lei),一(yi)類(lei)為(wei)天(tian)然環(huan)境(jing)(jing)(jing)暴露試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan),另一(yi)類(lei)為(wei)人工加速模(mo)(mo)(mo)擬鹽(yan)(yan)(yan)(yan)霧(wu)(wu)環(huan)境(jing)(jing)(jing)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)。人工模(mo)(mo)(mo)擬鹽(yan)(yan)(yan)(yan)霧(wu)(wu)環(huan)境(jing)(jing)(jing)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)是(shi)利(li)用一(yi)種具有(you)一(yi)定容(rong)積(ji)空間(jian)的(de)(de)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)設備——鹽(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)箱,在(zai)其(qi)容(rong)積(ji)空間(jian)內用人工的(de)(de)方法,造成鹽(yan)(yan)(yan)(yan)霧(wu)(wu)環(huan)境(jing)(jing)(jing)來(lai)對(dui)(dui)產品的(de)(de)耐鹽(yan)(yan)(yan)(yan)霧(wu)(wu)腐(fu)蝕性能質(zhi)量(liang)(liang)進行(xing)考(kao)核(he)。它與天(tian)然環(huan)境(jing)(jing)(jing)相比(bi),其(qi)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)環(huan)境(jing)(jing)(jing)的(de)(de)氯化(hua)物(wu)的(de)(de)鹽(yan)(yan)(yan)(yan)濃度,可(ke)以(yi)是(shi)一(yi)般天(tian)然環(huan)境(jing)(jing)(jing)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)含量(liang)(liang)的(de)(de)幾倍(bei)或(huo)幾十倍(bei),使腐(fu)蝕速度大大提高,對(dui)(dui)產品進行(xing)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan),得出結果的(de)(de)時間(jian)也大大縮短。如在(zai)天(tian)然暴露環(huan)境(jing)(jing)(jing)下對(dui)(dui)某(mou)產品樣品進行(xing)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan),待其(qi)腐(fu)蝕可(ke)能要(yao)1年,而在(zai)人工模(mo)(mo)(mo)擬鹽(yan)(yan)(yan)(yan)霧(wu)(wu)環(huan)境(jing)(jing)(jing)條(tiao)件下試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan),只要(yao)24小時,即可(ke)得到相似的(de)(de)結果。 人工模(mo)(mo)(mo)擬鹽(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)又包括中性鹽(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)、醋酸(suan)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)、銅鹽(yan)(yan)(yan)(yan)加速醋酸(suan)鹽(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)、交變鹽(yan)(yan)(yan)(yan)霧(wu)(wu)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)。
鹽霧試驗的種類:
(1) 中性(xing)鹽(yan)霧試(shi)驗(yan)(yan)(NSS試(shi)驗(yan)(yan))是出現zui早(zao)目(mu)前(qian)應(ying)用(yong)領域(yu)zui廣的一(yi)種加速(su)腐蝕試(shi)驗(yan)(yan)方法。它(ta)采用(yong)5%的氯(lv)化鈉鹽(yan)水(shui)溶液,溶液PH值調在(zai)中性(xing)范圍(6~7)作為噴霧用(yong)的溶液。試(shi)驗(yan)(yan)溫度均取35℃,要求鹽(yan)霧的沉(chen)降率在(zai)1~2ml/80cm2.h之間。
(2) 醋(cu)酸(suan)鹽(yan)霧試驗(ASS試驗)是在中(zhong)性鹽(yan)霧試驗的基(ji)礎上發展起來的。它(ta)是在5%氯化鈉(na)溶液中(zhong)加入一(yi)些冰(bing)醋(cu)酸(suan),使溶液的PH值降為(wei)3左(zuo)右(you),溶液變(bian)成(cheng)酸(suan)性,zui后形成(cheng)的鹽(yan)霧也由中(zhong)性鹽(yan)霧變(bian)成(cheng)酸(suan)性。它(ta)的腐蝕速度要(yao)比NSS試驗快3倍左(zuo)右(you)。
(3) 銅(tong)鹽(yan)(yan)加速(su)醋酸(suan)鹽(yan)(yan)霧(wu)試驗(yan)(CASS試驗(yan))是國(guo)外(wai)新近發展起來的一種(zhong)快速(su)鹽(yan)(yan)霧(wu)腐蝕試驗(yan),試驗(yan)溫度為50℃,鹽(yan)(yan)溶(rong)液中加入少(shao)量銅(tong)鹽(yan)(yan)—氯化銅(tong),強烈誘發腐蝕。它的腐蝕速(su)度大約(yue)是NSS試驗(yan)的8倍。
各種鹽霧試驗的試驗方法:
中性鹽霧試驗(yan)(NSS)
中(zhong)性(xing)鹽霧(wu)試驗(yan)是(shi)加速(su)腐蝕試驗(yan)的一(yi)種方(fang)法,是(shi)在的鹽霧(wu)箱(xiang)中(zhong)進行的.適用于鋼鐵件上的鍍鋅,鍍鎘(ge),氧化(hua)和(he)磷化(hua)等鍍覆層的耐(nai)蝕性(xing)檢驗(yan).
中性鹽霧(wu)試驗配(pei)制的鹽水(shui)為(wei)5%的NaCl溶液,PH為(wei)6.5~7.2,箱中溫(wen)度為(wei)35±2C,相對濕(shi)度為(wei)95%以(yi)上.
中(zhong)性鹽霧(wu)試驗噴(pen)霧(wu)沉降(jiang)為(wei)1mL~2Ml/80cm/h,收集(ji)的鹽霧(wu)NaCl濃度應為(wei)5±1%, PH為(wei)6.5~7.2,噴(pen)嘴(zui)壓(ya)強應為(wei)0.07MPa~0.1 Mpa.
中性鹽霧試驗(yan)的步驟(zou):
(1) 采(cai)用有(you)機溶劑清洗試樣(yang)表面(mian),使試樣(yang)表面(mian)無油污和其他(ta)對鍍(du)層具有(you)腐蝕(shi)的物品.
(2) 將試片置于鹽霧箱中,試片受試面朝上與垂直線成15~30℃
(3) 按檢驗(yan)周(zhou)期(qi)規定進行鹽霧(wu)試(shi)驗(yan).
(4) 取(qu)出(chu)試(shi)樣用流動(dong)水輕(qing)輕(qing)沖洗或用海綿帶水輕(qing)輕(qing)擦拭表面(mian)除(chu)去鹽(yan)沉積物,然后在80C~ 100C干燥(zao)30min左(zuo)右.
(5) 對試(shi)樣的(de)腐蝕等級給予評判.
醋酸鹽霧試驗(ASS法)
主要(yao)適用銅-鎳(nie)-鉻(ge)或(huo)鎳(nie)-鉻(ge)等裝飾性(xing)鍍層的耐蝕性(xing)試(shi)驗,阻力試(shi)驗用醋酸鹽(yan)霧溶液采用化學純冰醋酸配制,PH為(wei)3.0~3.1,噴霧收集液PH為(wei)3.2±0.1.試(shi)驗的其它要(yao)求(qiu)與(yu)中性(xing)鹽(yan)霧試(shi)驗方法相同(tong).
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