1.鹽霧箱樣(yang)品架的制備、養護及預處理
除(chu)另有規定(ding)外，可按GB/T1765－79(89)《測(ce)定(ding)耐濕(shi)熱(re)、耐鹽霧、耐候性(人工加速)的(de)(de)漆膜制備法》的(de)(de)規定(ding)制備和養護樣(yang)板，被(bei)(bei)測(ce)樣(yang)板的(de)(de)背面(mian)及周(zhou)邊可用(yong)被(bei)(bei)測(ce)產品(pin)或比被(bei)(bei)測(ce)產品(pin)更耐腐蝕(shi)的(de)(de)涂(tu)層(ceng)體系涂(tu)覆。如(ru)做(zuo)劃(hua)(hua)(hua)線(xian)(xian)試驗(yan)(yan)時，可用(yong)一種具有碳化鎢刀尖的(de)(de)劃(hua)(hua)(hua)線(xian)(xian)工具與樣(yang)板表面(mian)接觸，劃(hua)(hua)(hua)出一條均勻的(de)(de)、劃(hua)(hua)(hua)穿(chuan)底材上所有有機涂(tu)層(ceng)的(de)(de)不帶(dai)毛刺的(de)(de)V字型切口(kou)的(de)(de)亮(liang)線(xian)(xian)。如(ru)需做(zuo)劃(hua)(hua)(hua)穿(chuan)金屬(shu)鍍(du)層(ceng)的(de)(de)試驗(yan)(yan)，其劃(hua)(hua)(hua)穿(chuan)程度應由生(sheng)產廠與用(yong)戶之間商定(ding)。如(ru)果(guo)用(yong)戶需要，經商定(ding)也(ye)可劃(hua)(hua)(hua)出幾(ji)條線(xian)(xian)(交叉線(xian)(xian)、平(ping)行線(xian)(xian))，劃(hua)(hua)(hua)線(xian)(xian)質量可借助低倍放大鏡觀察。
2.鹽霧箱樣品架的(de)投試(shi)(shi)、試(shi)(shi)驗(yan)及檢查
養護期結束(shu)后(hou)的樣(yang)(yang)(yang)(yang)板(ban)(ban)留出一塊(kuai)作標準(zhun)板(ban)(ban)，其余3塊(kuai)投入試(shi)驗箱內進行曝露(lu)試(shi)驗。樣(yang)(yang)(yang)(yang)板(ban)(ban)應(ying)表(biao)面(mian)朝上(shang)放(fang)在樣(yang)(yang)(yang)(yang)板(ban)(ban)支架(jia)上(shang)，樣(yang)(yang)(yang)(yang)板(ban)(ban)之間及(ji)(ji)樣(yang)(yang)(yang)(yang)板(ban)(ban)與(yu)箱體(ti)之間均不允許(xu)接觸(chu)，且被測樣(yang)(yang)(yang)(yang)板(ban)(ban)不應(ying)層(ceng)疊(die)放(fang)置，避免(mian)液滴從上(shang)層(ceng)樣(yang)(yang)(yang)(yang)板(ban)(ban)濺落到下層(ceng)樣(yang)(yang)(yang)(yang)板(ban)(ban)上(shang)影響試(shi)驗結果。樣(yang)(yang)(yang)(yang)板(ban)(ban)在試(shi)板(ban)(ban)架(jia)上(shang)的排(pai)(pai)(pai)(pai)列應(ying)以有規(gui)律的間隔時間改變，例如前排(pai)(pai)(pai)(pai)與(yu)中排(pai)(pai)(pai)(pai)及(ji)(ji)后(hou)排(pai)(pai)(pai)(pai)進行交換。
3.鹽霧箱試驗過程中樣品架需定期(qi)檢(jian)查
鹽霧(wu)試(shi)驗周期比較長，一般是幾(ji)佰小時、1000h、2000h和4000h，甚至(zhi)更長時間也(ye)(ye)有采用。試(shi)驗時間可(ke)參照(zhao)相關產品(pin)標(biao)準的(de)規(gui)(gui)定。因為(wei)標(biao)準中(zhong)規(gui)(gui)定每24h需檢查一次樣(yang)板(ban)，故試(shi)驗時間一般為(wei)24h的(de)倍(bei)數。但也(ye)(ye)可(ke)按美國(guo)ASTMD117-1997標(biao)準中(zhong)推薦的(de)曝露周期，即12，24，48，96，200，500，720h. |
