60. Aluminium hauv molten zinc cuam tshuam li cas kub -dip galvanizing?

Aluminium (A1) yog silvery - hlau dawb nrog lub ntsej muag -centered cubic (FCC) crystal qauv. Nws cov lattice tas li ntsuas 404959.6 nm, atomic mass yog 26.8, melting point 658 degree, thiab boiling point 2000 degree. Cov khoom lag luam zinc tsis muaj txhuas, uas yog txhob txwm ntxiv thaum kub -dip galvanizing. Cov txheej txheem no ua haujlwm rau peb lub hom phiaj tseem ceeb: txhim kho qhov ci ntsa iab ntawm cov yeeb nkab steel galvanized, txhim kho kev yooj yim, hloov kho cov txheej txheem ntawm cov hlau{11}}zinc alloy txheej, thiab neutralizing cov teebmeem ntawm cov hlau hauv cov zinc molten. Cov ntsiab lus muaj raws li hauv qab no: (1) Txhuas txhim kho lub ntsej muag luster thiab yooj ntawm galvanized steel kav.
Raws li txoj cai, tsuas yog 0.02% txhuas cov ntsiab lus hauv zinc da dej yuav txaus kom ua tiav lub hom phiaj no. Txawm li cas los xij, txij li cov txhuas nkag tau yooj yim oxidizes ntawm zinc nto, cov ntaub ntawv pov thawj pom tau hais tias ntxiv kwv yees li 0.2% txhuas yog tsim nyog los tswj qhov yuav tsum tau 0.02% qib. Qhov muaj zog affinity ntawm txhuas thiab oxygen tsim ib txheej aluminium oxide uas zoo thaiv cov pa oxygen, tiv thaiv ob qho tib si hauv qab molten aluminium thiab zinc los ntawm oxidation. Qhov kev tiv thaiv no tseem tiv thaiv oxidation ntawm lwm cov hlau hauv zinc da dej. Raws li paub zoo, zinc oxidation ua rau daj zinc oxide, thiab cov hlau lead thiab cadmium oxides pom cov xim daj zoo sib xws. Yog tsis muaj txhuas lub luag hauj lwm tiv thaiv, lub galvanized nto yuav ua rau hnyav stained nrog daj compounds, ho cuam tshuam nws luster. Yog li ntawd, ntxiv qhov tsim nyog ntawm txhuas yog qhov tseem ceeb hauv kub -dip galvanizing kom ua tiav qhov ci tiav. Ntxiv mus, 0.2% txhuas cov ntsiab lus nyob rau hauv zinc da dej tsis tsuas yog yields zoo zoo nkauj qauv tab sis kuj xyuas kom meej tshwj xeeb saj zawg zog nyob rau hauv lub galvanized txheej.
Txawm li cas los xij, American Society for Testing Materials (ASTM) pom zoo tias cov txhuas yuav tsum tsis txhob siv los ua cov khoom siv hlau ntxiv, thiab yog tias siv, nws cov ntsiab lus yuav tsum raug txwv tsawg dua 0.01%.
(2) Hloov cov Microstructure ntawm Galvanized Layers Theoretically, ib qho txhuas cov ntsiab lus ntawm 0.2-0.3% nyob rau hauv molten zinc yog txaus los hloov cov microstructure ntawm galvanized txheej. Txawm li cas los xij, hauv kev tsim tawm, txhuas tau nkag siab nrog cov pa oxygen hauv cov zinc molten, ua rau nws noj. Txhawm rau tswj hwm lub hom phiaj ntawm cov ntsiab lus txhuas, kwv yees li 1.5% -3.5% ntawm txhuas yuav tsum tau ntxiv. Txhawm rau ua kom pom tias cov ntsiab lus txhuas cuam tshuam li cas rau microstructure, peb txheeb xyuas qhov kev hloov pauv ntawm qhov qis mus rau siab aluminium concentrations: Kev nce ntawm 0.05% hauv cov ntsiab lus txhuas txhim kho qhov ci ntsa iab ntawm txheej galvanized tab sis tsis cuam tshuam rau nws cov microstructure. Yog li, txheej txheej galvanized khaws cia tib yam li cov khoom siv uas ua los ntawm cov kua zinc ntshiab, muaj cov txheej txheem sib txuas (Phase a), txheej nruab nrab (Phase Y), cov txheej txheej me ntsis tawg (Phase 81), thiab txheej ntab ntab (Phase S) ntawm cov zinc ntshiab (Phase n). Qhov sib txawv tseem ceeb nyob hauv qhov sib txawv crystalline morphology ntawm cov theem piv rau cov kua ntshiab zinc.
Thaum cov ntsiab lus txhuas nyob rau hauv zinc kua yog 0.1%, lub crystallization ntawm txheej ntab (3 theem) yog nyob rau hauv daim ntawv ntawm ib tug loj thaiv, thiab nws tsis yog ib tug nruam txheej, tab sis ib yam ntawm cov sib cais inclusions.
Thaum cov ntsiab lus txhuas hauv cov kua zinc yog 0.15%, qhov kev faib tawm ntawm cov txheej ntab ntab (theem 5) tsis yog txheej txuas ntxiv, tab sis qee qhov loj dua, sib cais crystalline pawg, thiab tsuas yog cov kab sib chaws (theem 81) nthuav tawm cov qauv ntom ntom me ntsis.
Thaum cov ntsiab lus txhuas hauv zinc da dej nce mus txog 0.24%, cov nyhuv alloying ua tau zoo heev los tiv thaiv corrosion. Yog tias zinc da dej yog khaws cia ntawm 440℃rau 1 teev ntawm plating, tsis muaj kev cuam tshuam tshwm sim thaum tshem tawm thiab tshuaj xyuas. Yog li ntawd, txheej galvanized ntawm tus qauv tsuas yog los ntawm cov zinc txheej ntshiab. Qhov no tshwm sim vim tias txhuas reacts nrog cov yeeb nkab steel los tsim FeAl₃ (los yog Fe₂AlO) cov yeeb yaj kiab, uas inhibits qhov sib txawv ntawm cov hlau ions mus rau zinc txheej.
Raws li tau pom saum toj no, cov ntsiab lus ntawm txhuas yog qhov tseem ceeb hauv kev hloov kho microstructure ntawm txheej galvanized. Thaum cov ntsiab lus ntawm txhuas raug kho, lwm cov txheej txheem tsis ua haujlwm -xws li zinc immersion lub sij hawm, fluidity (raws li qhia hauv daim duab 3-5), thiab kub- kuj cuam tshuam rau zinc txheej microstructure. Yog li ntawd, nyob rau hauv kub-dip galvanizing ntau lawm, interplay ntawm peb yam no yog tswj los ntawm cov txheej txheem specifications. Tsuas yog los ntawm kev ua raws li cov txheej txheem kev ua haujlwm tau teev tseg yuav ua tiav cov txheej txheem galvanized.
(3) Cov nyhuv ntawm cov hlau hauv zinc da dej yog offset vim tias txhuas tuaj yeem ua ke nrog hlau hauv zinc da dej los ua peb lub tebchaw, xws li FeAl, FeAl2 thiab FeAl3, uas txo cov nyhuv ntawm galvanized txheej.