labarai

Gabatarwa
Cristobalite low density SiO2 homomorphous bambance-bambancen, da kuma thermodynamic kewayon kwanciyar hankali ne 1470 ℃ ~ 1728 ℃ (a karkashin al'ada matsa lamba). β Cristobalite shine lokacin yanayin zafi mai girma, amma ana iya adana shi a cikin nau'in metastable zuwa ƙananan zafin jiki har sai canjin yanayin canji ya faru a kusan 250 ℃ α Cristobalite. Kodayake ana iya yin crystallized cristobalite daga SiO2 narke a cikin yankin kwanciyar hankali na ma'aunin zafi da sanyio, yawancin cristobalite a cikin yanayi yana samuwa a ƙarƙashin yanayin haɓaka. Alal misali, diatomite ya canza zuwa cristobalite chert ko microcrystalline opal (opal CT, opal C) a lokacin digenesis, kuma babban matakan ma'adinai su ne α Cristobalite), wanda zafin canjin yanayi ya kasance a cikin kwanciyar hankali na ma'adini; A karkashin yanayin granulite facies metamorphism, cristobalite precipitated daga arziki Na Al Si narke, wanzu a cikin garnet a matsayin hada da coexisted tare da albite, forming yanayin zafi da matsa lamba na 800 ℃, 01GPa, kuma a cikin barga yankin ma'adini. Bugu da ƙari, an kafa cristobalite metastable a cikin yawancin kayan ma'adinai marasa ƙarfe a lokacin jiyya na zafi, kuma yanayin da aka samu yana cikin yankin kwanciyar hankali na thermodynamic na tridymite.
Tsarin tsari
Diatomite yana canzawa zuwa cristobalite a 900 ℃ ~ 1300 ℃; Opal yana canzawa zuwa cristobalite a 1200 ℃; Quartz kuma an kafa shi a cikin kaolinite a 1260 ℃; Na roba MCM-41 mesoporous SiO2 sieve kwayoyin halitta an rikide zuwa cristobalite a 1000 ℃. Ana kuma kafa cristobalite metastable a cikin wasu matakai kamar yumbu sintering da shirye-shiryen mullite. Don bayanin tsarin samar da metastable na cristobalite, an yarda cewa tsari ne wanda ba shi da ma'auni na thermodynamic, galibi ana sarrafa shi ta hanyar injin motsa jiki. Dangane da yanayin samuwar ƙwayar cuta na cristobalite da aka ambata a sama, kusan gaba ɗaya an yarda cewa cristobalite yana canzawa daga SiO2 amorphous, har ma a cikin aiwatar da maganin zafi na kaolinite, shirye-shiryen mullite da yumbu sintering, cristobalite kuma an canza shi daga amorphous SiO2.
Manufar
Tun lokacin samar da masana'antu a cikin 1940s, an yi amfani da samfuran baƙar fata na farin carbon azaman abubuwan ƙarfafawa a samfuran roba. Bugu da kari, ana iya amfani da su a masana'antar harhada magunguna, maganin kashe kwari, tawada, fenti, fenti, man goge baki, takarda, abinci, abinci, kayan kwalliya, batura da sauran masana'antu.
Tsarin sinadarai na farin carbon baki a cikin hanyar samarwa shine SiO2nH2O. Domin amfani da shi yayi kama da na carbon baƙar fata kuma fari ne, ana kiransa farin carbon baki. Dangane da hanyoyin samarwa daban-daban, ana iya raba farin baƙar fata na carbon zuwa baƙar fata mai tsinkewa (silica precipitated hydrated silica) da farin farin carbon baki (fumed silica). Samfuran biyu suna da hanyoyin samarwa daban-daban, kaddarorin da amfani. Hanyar lokacin iskar gas galibi tana amfani da silicon tetrachloride da silicon dioxide da aka samu ta hanyar konewar iska. Barbashi suna da kyau, kuma girman barbashi na tsakiya zai iya zama ƙasa da 5 microns. Hanyar hazo ita ce hado silica ta hanyar ƙara sulfuric acid zuwa sodium silicate. Girman barbashi na tsakiya shine kusan 7-12 microns. Silica fumed yana da tsada kuma ba sauki don shayar da danshi ba, don haka ana amfani dashi sau da yawa azaman matting wakili a cikin sutura.
Maganin gilashin ruwa na hanyar nitric acid yana amsawa tare da nitric acid don samar da silicon dioxide, wanda aka shirya shi zuwa silicon dioxide na lantarki ta hanyar kurkura, pickling, kurkurawar ruwa da bushewa.