1.鹽霧箱樣品架的制備、養護及預(yu)處(chu)理
除另有(you)規(gui)定外,可按GB/T1765-79(89)《測(ce)(ce)定耐(nai)濕熱、耐(nai)鹽霧、耐(nai)候性(人工加速)的(de)(de)漆(qi)膜制(zhi)備法》的(de)(de)規(gui)定制(zhi)備和養護樣(yang)板(ban),被(bei)測(ce)(ce)樣(yang)板(ban)的(de)(de)背面(mian)及周邊可用(yong)被(bei)測(ce)(ce)產品(pin)或比被(bei)測(ce)(ce)產品(pin)更耐(nai)腐蝕的(de)(de)涂(tu)層體(ti)系涂(tu)覆。如(ru)做(zuo)劃(hua)(hua)線(xian)試驗(yan)時,可用(yong)一種具(ju)有(you)碳化(hua)鎢(wu)刀尖的(de)(de)劃(hua)(hua)線(xian)工具(ju)與樣(yang)板(ban)表(biao)面(mian)接觸,劃(hua)(hua)出(chu)一條均勻的(de)(de)、劃(hua)(hua)穿底(di)材上(shang)所有(you)有(you)機涂(tu)層的(de)(de)不帶毛刺的(de)(de)V字型切口的(de)(de)亮線(xian)。如(ru)需做(zuo)劃(hua)(hua)穿金屬鍍層的(de)(de)試驗(yan),其劃(hua)(hua)穿程度應由生(sheng)產廠(chang)與用(yong)戶之間商(shang)定。如(ru)果用(yong)戶需要(yao),經(jing)商(shang)定也可劃(hua)(hua)出(chu)幾條線(xian)(交叉線(xian)、平行線(xian)),劃(hua)(hua)線(xian)質量可借(jie)助低倍(bei)放大鏡(jing)觀察。
2.鹽霧箱樣品架的投試、試驗及檢查
養護期(qi)結束后的樣板(ban)(ban)(ban)留出(chu)一塊作(zuo)標準板(ban)(ban)(ban),其(qi)余3塊投入試驗(yan)箱(xiang)內(nei)進(jin)行曝(pu)露(lu)試驗(yan)。樣板(ban)(ban)(ban)應表面朝上(shang)放在(zai)樣板(ban)(ban)(ban)支(zhi)架上(shang),樣板(ban)(ban)(ban)之間(jian)及樣板(ban)(ban)(ban)與箱(xiang)體之間(jian)均不允許接觸,且(qie)被測樣板(ban)(ban)(ban)不應層(ceng)疊放置,避免液滴從上(shang)層(ceng)樣板(ban)(ban)(ban)濺落到下層(ceng)樣板(ban)(ban)(ban)上(shang)影(ying)響試驗(yan)結果。樣板(ban)(ban)(ban)在(zai)試板(ban)(ban)(ban)架上(shang)的排(pai)列應以有規律的間(jian)隔(ge)時間(jian)改變,例如前排(pai)與中(zhong)排(pai)及后排(pai)進(jin)行交(jiao)換。
3.鹽霧箱試(shi)驗過程中樣品架需定(ding)期檢查
鹽霧試(shi)驗周期比較長(chang),一(yi)般(ban)是(shi)幾佰(bai)小時(shi)(shi)、1000h、2000h和4000h,甚至更長(chang)時(shi)(shi)間也有(you)采用(yong)。試(shi)驗時(shi)(shi)間可參(can)照相關產品標準的(de)規定。因為(wei)標準中規定每24h需檢查一(yi)次樣板,故試(shi)驗時(shi)(shi)間一(yi)般(ban)為(wei)24h的(de)倍數。但也可按美國ASTMD117-1997標準中推薦的(de)曝(pu)露周期,即12,24,48,96,200,500,720h. |