izindaba

Isingeniso
I-Cristobalite iwuhlobo oluphansi lokuminyana kwe-SiO2 homomorphous, futhi uhla lwayo lokuzinza kwe-thermodynamic luyi-1470 ℃~1728 ℃ (ngaphansi kwengcindezi evamile). I-β Cristobalite yisigaba sayo sezinga eliphezulu lokushisa, kodwa ingagcinwa ngendlela ekwazi ukumetastable ibe izinga lokushisa eliphansi kakhulu kuze kube ukuguqulwa kwesigaba sokushintsha kwenzeka cishe ku-250 ℃ α Cristobalite. Nakuba i-cristobalite ingafakwa ku-crystallized isuka ku-SiO2 incibilike endaweni yayo yokuzinza ye-thermodynamic, i-cristobalite eningi ngokwemvelo yakheka ngaphansi kwezimo ze-metastable. Isibonelo, i-diatomite ishintsha ibe yi-cristobalite chert noma i-microcrystalline opal (i-opal CT, i-opal C) ngesikhathi se-diagenesis, futhi izigaba zabo zamaminerali eziyinhloko ziyi-α Cristobalite), izinga lokushisa layo lokushintsha lisendaweni ezinzile ye-quartz; Ngaphansi kwesimo se-granulite facies metamorphism, i-cristobalite encibilikisiwe esuka ku-Na Al Si ecebile, yayikhona ku-garnet njengokufakwa futhi yayihlala ne-albite, yakha isimo sokushisa nengcindezi engu-800 ℃, 01GPa, futhi endaweni ezinzile ye-quartz. Ngaphezu kwalokho, i-cristobalite ye-metastable nayo yakhiwe ezintweni eziningi zamaminerali angewona ezensimbi ngesikhathi sokwelashwa kokushisa, futhi izinga lokushisa lokubunjwa litholakala endaweni yokuzinza kwe-thermodynamic ye-tridymite.
Indlela yokwenza
I-Diatomite ishintsha ibe yi-cristobalite ku-900 ℃ ~ 1300 ℃; I-Opal ishintsha ibe yi-cristobalite ku-1200 ℃; I-quartz nayo yakheka ku-kaolinite ku-1260 ℃; I-synthetic ye-MCM-41 mesoporous SiO2 i-molecular sieve yaguqulwa yaba i-cristobalite ku-1000 ℃. I-Metastable cristobalite nayo yakheka kwezinye izinqubo ezifana ne-ceramic sintering kanye nokulungiswa kwe-mullite. Ukuze uthole incazelo yendlela yokwakheka kwe-metastable ye-cristobalite, kuyavunyelwana ukuthi iyinqubo ye-thermodynamic engalingani, elawulwa ikakhulukazi indlela ye-reaction kinetics. Ngokwemodi yokwakheka kwe-metastable ye-cristobalite okukhulunywe ngayo ngenhla, cishe kukholakala ngokuvumelanayo ukuthi i-cristobalite iguqulwa isuka ku-amorphous SiO2, ngisho nasenqubo yokwelashwa kokushisa kwe-kaolinite, ukulungiswa kwe-mullite kanye ne-ceramic sintering, i-cristobalite nayo iguqulwa isuka ku-amorphous SiO2.
Inhloso
Kusukela ekukhiqizweni kwezimboni ngawo-1940s, imikhiqizo ye-carbon emhlophe isetshenziswe kabanzi njenge-ejenti yokuqinisa emikhiqizweni yenjoloba. Ngaphezu kwalokho, zingasetshenziswa futhi embonini yezemithi, isibulala-zinambuzane, uyinki, upende, upende, umuthi wamazinyo, iphepha, ukudla, okuphakelayo, izimonyo, amabhethri nezinye izimboni.
Ifomula yamakhemikhali yekhabhoni emnyama emhlophe endleleni yokukhiqiza ithi SiO2nH2O. Ngenxa yokuthi ukusetshenziswa kwayo kufana nekhabhoni emnyama futhi imhlophe, ibizwa ngokuthi i-white carbon black. Ngokwezindlela ezihlukene zokukhiqiza, ikhabhoni emnyama emhlophe ingahlukaniswa ibe yi-carbon black precipitated (precipitated hydrated silica) kanye ne-fumed white carbon black (fumed silica). Le mikhiqizo yomibili inezindlela ezihlukene zokukhiqiza, izakhiwo kanye nokusetshenziswa. Indlela yesigaba segesi ikakhulukazi isebenzisa i-silicon tetrachloride ne-silicon dioxide etholakala ngokushiswa komoya. Izinhlayiya zilungile, futhi usayizi wezinhlayiyana omaphakathi ungaba ngaphansi kwama-microns angu-5. Indlela yemvula iwukuba imvula isilica ngokungeza i-sulfuric acid ku-sodium silicate. Usayizi wezinhlayiyana omaphakathi cishe u-7-12 microns. I-silica enentuthu iyabiza futhi akulula ukumunca umswakama, ngakho-ke ivamise ukusetshenziswa njenge-agent yokuhlanganisa ezimbotsheni.
Isixazululo sengilazi samanzi sendlela ye-nitric acid sihlangana ne-nitric acid ukuze kukhiqizwe i-silicon dioxide, ebese ilungiswa ibe yi-electronic grade silicon dioxide ngokuhlanjululwa, ukukha, ukuhlanjululwa kwamanzi kanye nokuphelelwa amandla kwamanzi.