iindaba

Intshayelelo
I-Cristobalite i-low density ye-SiO2 i-homomorphous variant, kwaye uluhlu lwayo lokuzinza kwe-thermodynamic yi-1470 ℃ ~ 1728 ℃ (phantsi koxinzelelo oluqhelekileyo). I-β Cristobalite yinqanaba eliphezulu lobushushu, kodwa inokugcinwa kwifom ye-metastable ukuya kwiqondo lokushisa eliphantsi kakhulu kuze kube yilapho ukuguqulwa kwesigaba sokutshintsha kwenzeka malunga ne-250 ℃ α Cristobalite. Nangona i-cristobalite inokuthi i-crystallized ukusuka kwi-SiO2 inyibilika kwindawo yayo yozinzo lwe-thermodynamic, ininzi ye-cristobalite kwindalo yenziwa phantsi kweemeko ze-metastable. Ngokomzekelo, i-diatomite iguqula i-cristobalite chert okanye i-microcrystalline opal (i-opal CT, i-opal C) ngexesha le-diagenesis, kunye nezigaba zabo eziphambili zeminerali ziyi-α Cristobalite), obushushu bayo benguqu buhlala kwindawo ezinzileyo ye-quartz; Ngaphantsi kwemeko ye-granulite facies metamorphism, i-cristobalite ekhutshwe kwisityebi se-Na Al Si enyibilikayo, yayikhona kwi-garnet njengento edibeneyo kwaye yayihlala kunye ne-albite, yenza iqondo lokushisa kunye noxinzelelo lwe-800 ℃, i-01GPa, kwakhona kwindawo ezinzileyo ye-quartz. Ukongezelela, i-cristobalite ye-metastable nayo yenziwe kwizinto ezininzi zamaminerali angeyiyo-metallic ngexesha lonyango lobushushu, kwaye ubushushu bokwakheka bubekwe kwindawo yokuzinza kwe-thermodynamic ye-tridymite.
Indlela yokwenza
I-Diatomite iguqula ibe yi-cristobalite kwi-900 ℃ ~ 1300 ℃; I-Opal iguqula ibe yicristobalite kwi-1200 ℃; I-quartz nayo yenziwe kwi-kaolinite kwi-1260 ℃; Ukwenziwa kwe-MCM-41 mesoporous SiO2 i-molecular sieve yatshintshwa yaba yicristobalite kwi-1000 ℃. I-Metastable cristobalite yenziwe nakwezinye iinkqubo ezifana ne-ceramic sintering kunye nokulungiswa kwe-mullite. Ukufumana inkcazo yendlela yokwenza i-metastable ye-cristobalite, kuvunyelwene ukuba yinkqubo ye-thermodynamic engalinganiyo, ilawulwa ngokukodwa yi-reaction kinetics mechanism. Ngokwendlela yokwenza i-metastable ye-cristobalite ekhankanywe ngasentla, kukholelwa ukuba i-cristobalite iguqulwa ukusuka kwi-amorphous SiO2, nakwinkqubo ye-kaolinite yonyango lokushisa, ukulungiswa kwe-mullite kunye ne-ceramic sintering, i-cristobalite nayo iguqulwe kwi-amorphous SiO2.
Injongo
Ukusukela kwimveliso yeshishini kwiminyaka yoo-1940, iimveliso ezimhlophe zekhabhoni zisetyenziswe ngokubanzi njengee-agent zokuqinisa kwiimveliso zerabha. Ukongeza, zinokusetyenziswa kwishishini lamayeza, i-pesticide, inki, ipeyinti, ipeyinti, intlama yamazinyo, iphepha, ukutya, ukutya, izinto zokuthambisa, iibhetri kunye namanye amashishini.
Ifomula yeekhemikhali zekhabhoni emhlophe emnyama kwindlela yokuvelisa yiSiO2nH2O. Ngenxa yokuba ukusetyenziswa kwayo kufana nekhabhoni emnyama kwaye imhlophe, ibizwa ngokuba yi-white carbon black. Ngokweendlela ezahlukeneyo zokuvelisa, ikhabhoni emnyama emhlophe inokohlulwa ibe yi-precipitated white carbon black (precipitated hydrated silica) kunye ne-fumed white carbon black (fumed silica). Ezi mveliso zimbini zineendlela ezahlukeneyo zokuvelisa, iipropati kunye nokusetyenziswa. Indlela yesigaba segesi isebenzisa ikakhulu i-silicon tetrachloride kunye ne-silicon dioxide efunyenwe ngokutshiswa komoya. Iinqununu zilungile, kwaye ubukhulu becala obuphakathi bunokuba ngaphantsi kwe-5 microns. Indlela yokunciphisa i-precipitate silica ngokongeza i-asidi ye-sulfuric kwi-sodium silicate. Ubungakanani beqhekeza eliphakathi li malunga ne-7-12 microns. I-silica eqhumayo iyabiza kwaye akukho lula ukufunxa ukufuma, ngoko isoloko isetyenziswa njenge-agent yokulinganisa kwiingubo.
Isisombululo seglasi samanzi sendlela ye-nitric acid isabela nge-asidi ye-nitric ukuvelisa isilicon dioxide, ethi ke ilungiswe kwi-electron grade silicon dioxide ngokuhlamba, ukukha, ukuhlanjululwa kwamanzi kunye nokuphelelwa ngamanzi emzimbeni.