72. Vim li cas txhuas txwv tsis pub nyob rau hauv zinc da dej kub -dip galvanizing?

Hauv cov pa "ntub" kub-dip galvanizing txheej txheem, txhuas feem ntau tsis suav nrog zinc da dej. Thaum aluminium tau qhia, nws qhov ceev dua ua rau nws ntab rau ntawm zinc nto. Lub flux, tau muab tso ncaj qha rau saum lub zinc da dej, thawj zaug reacts nrog molten txhuas txheej, tsim cov volatile aluminium trichloride (AlCl₃) los ntawm kev sib npaug hauv qab no: 3ZnCl₂ + 2Al → 3Zn + 2AlCl₃↑. Cov tshuaj tiv thaiv no qhia tau hais tias tsawg npaum li cas cov zinc reactive (ZnCl₂) yog hloov los ntawm ntau reactive txhuas, tsim AlCl₃. Remarkably, AlCl₃ boils ntawm 123 degree, ua rau sai evaporation ntawm flux. Qhov seem AlCl₃ ces reacts nrog unvolatilized txhuas los tsim insoluble acids thiab txhuas chloride (AlCl₃) thiab ammonia (NH₃), uas boil ntawm 400 degree. Cov txheej txheem evaporation no deplete flux cov ntsiab lus chlorine tseem ceeb rau kev pab plating, thaum kawg ua rau cov txheej txheem mottled ntawm cov kav dej galvanized.