nhau

Nhanganyaya
Cristobalite ndeye yakaderera density SiO2 homomorphous variant, uye yayo thermodynamic kugadzikana renji i1470 ℃ ~ 1728 ℃ (pasi peyakajairika pressure). β Cristobalite chikamu chayo chepamusoro-tembiricha, asi inogona kuchengetwa mune metastable fomu kusvika kune yakaderera tembiricha kudzamara shanduko yerudzi rwekuchinja ichiitika panenge 250 ℃ α Cristobalite. Kunyange zvazvo cristobalite inogona kucheneswa kubva kuSiO2 yakanyunguduka munzvimbo yayo ye thermodynamic kugadzikana, yakawanda cristobalite muchisikigo inoumbwa pasi pemamiriro ekugadzirisa. Semuenzaniso, diatomite inoshandura kuva cristobalite chert kana microcrystalline opal (opal CT, opal C) panguva ye diagenesis, uye zvikamu zvavo zvemaminerari ndeye α Cristobalite), iyo inoshanduka yekushisa iri munzvimbo yakagadzikana ye quartz; Pasi pemamiriro egranulite facies metamorphism, cristobalite yakanyungudutswa kubva kune akapfuma Na Al Si melt, yaivepo mugarnet sechinhu chinosanganisirwa uye yakagara nealbite, ichigadzira tembiricha uye kumanikidza mamiriro e800 ℃, 01GPa, zvakare munzvimbo yakagadzikana yequartz. Uye zvakare, metastable cristobalite inoumbwawo mune dzakawanda dzisiri-metallic mineral zvinhu panguva yekupisa kupisa, uye tembiricha yekugadzira inowanikwa mu thermodynamic kugadzikana zone ye tridymite.
Formative mechanism
Diatomite inoshandura kuita cristobalite pa900 ℃ ~ 1300 ℃; Opal inoshandura kuita cristobalite pa1200 ℃; Quartz inoumbwawo mu kaolinite pa 1260 ℃; Iyo yakagadzirwa MCM-41 mesoporous SiO2 molecular sieve yakashandurwa kuita cristobalite pa1000 ℃. Metastable cristobalite inoumbwawo mune mamwe maitiro akadai seceramic sintering uye mullite kugadzirira. Kune tsananguro ye metastable yekugadzira metastable ye cristobalite, inobvumirana kuti isiri-equilibrium thermodynamic process, inonyanya kudzorwa neiyo reaction kinetics mechanism. Maererano ne metastable formation mode ye cristobalite yataurwa pamusoro apa, inenge yakabvumirana inotendwa kuti cristobalite inoshandurwa kubva kune amorphous SiO2, kunyange mukugadzirwa kwekaolinite kupisa, kugadzirira mullite uye ceramic sintering, cristobalite inoshandurwawo kubva kune amorphous SiO2.
Chinangwa
Kubva kugadzirwa kwemaindasitiri muma1940s, chena kabhoni dema zvigadzirwa zvakashandiswa zvakanyanya senge yekusimbisa vamiririri mune zvigadzirwa zverabha. Pamusoro pezvo, anogona zvakare kushandiswa muindasitiri yemishonga, mushonga wezvipembenene, inki, pendi, pendi, mushonga wemazino, bepa, chikafu, chikafu, zvizorwa, mabhatiri uye mamwe maindasitiri.
Iyo kemikari fomula yechena kabhoni dema mune yekugadzira nzira ndeyeSiO2nH2O. Nemhaka yokuti kushandiswa kwaro kwakafanana nekokwe carbon black uye ichena, inonzi white carbon black. Zvinoenderana neyakasiyana nzira dzekugadzira, chena kabhoni dema inogona kukamurwa kuita yakanaya chena kabhoni dema (yakanaya hydrated silica) uye fumed chena kabhoni dema (fumed silica). Izvo zvigadzirwa zviviri zvine nzira dzakasiyana dzekugadzira, zvivakwa uye mashandisiro. Iyo gasi chikamu nzira inonyanya kushandisa silicon tetrachloride uye silicon dioxide inowanikwa nemhepo inopisa. Izvo zvimedu zvakanaka, uye yepakati particle size inogona kuva isingasviki 5 microns. Precipitation nzira ndeyekudzikisa silica nekuwedzera sulfuric acid kune sodium silicate. Iyo yepakati particle size inenge 7-12 microns. Iyo fumed silica inodhura uye haisi nyore kutora unyoro, saka inowanzoshandiswa sematting agent mumachira.
Iyo yemvura girazi mhinduro ye nitric acid nzira inopindirana ne nitric acid kugadzira silicon dioxide, iyo inozogadzirirwa mumagetsi giredhi silicon dioxide kuburikidza nekusuka, pickling, deionized mvura rinsing uye kupera mvura.