Chimiro chegirazi
Iyo physicochemical properties yegirazi haisi kungogadziriswa chete nemakemikari ayo, asiwo yakanyatsobatana nemaitiro ayo.Chete nekunzwisisa hukama hwemukati pakati pechimiro, kuumbwa, chimiro uye kuita kwegirazi, zvinokwanisika kugadzira zvigadzirwa zvegirazi kana zvigadzirwa zvine akafanotemerwa physicochemical properties nekushandura kemikari, nhoroondo yekupisa kana kushandisa dzimwe nzira dzemuviri nemakemikari kurapwa.
Hunhu hwegirazi
Girazi ibazi re amorphous solid, iyo amorphous material ine yakasimba mechanical properties.Inowanzonzi "supercooled liquid".Muchisikirwo, kune matunhu maviri echinhu chakasimba: yakanaka mamiriro uye isiri yakanaka.Iyo inodaidzwa kuti nyika isingabereki ndiyo mamiriro echinhu chakasimba chinowanikwa nenzira dzakasiyana uye chinoratidzwa nekusagadzikana kwemaitiro.Glassy state imhando yeasina mwero wakasimba.Maatomu ari mugirazi haana kurongeka kwenguva refu munzvimbo yakaita sekristaro, asi akafanana nemvura uye ane hurongwa hupfupi hwakaodha.Girazi rinogona kuchengetedza chimwe chimiro chakasimba, asi kwete semvura inoyerera pasi pehuremu hwayo.Zvinhu zvegirazi zvine maitiro makuru anotevera.
(1) Kurongeka kwezvikamu zveisotropic girazi zvinhu hazvina kurongeka uye nenhamba dzakafanana.Nokudaro, kana pasina kushushikana kwemukati mugirazi, maitiro ayo emuviri nemakemikari (zvakadai sekuoma, elastic modulus, thermal expansion coefficient, thermal conductivity, refractive index, conductivity, nezvimwewo) zvakafanana kumativi ose.Nekudaro, kana paine kushushikana mugirazi, iyo yunifomu yechimiro ichaparadzwa, uye girazi rinoratidza anisotropy, senge pachena optical nzira musiyano.
(2) Metastability
Chikonzero nei girasi iri mune metastable mamiriro ekuti girazi rinowanikwa nekukurumidza kutonhora kwekunyungudika.Nekuda kwekuwedzera kwakanyanya kwe viscosity panguva yekutonhora, zvimedu hazvina nguva yekugadzira nguva dzose kurongeka kwemakristasi, uye simba remukati rehurongwa harisi pamutengo wakaderera, asi mune metastable state;Zvisinei, kunyange zvazvo girazi iri munzvimbo yakakwirira yesimba, haigoni kungoerekana yachinja kuva chigadzirwa nekuda kwekukwirira kwayo kwepamusoro pakupisa kwekamuri;Chete pasi pemamwe mamiriro ekunze, kureva kuti, isu tinofanirwa kukurira chipingamupinyi chinogona kubva pazvinhu zvegirazi kusvika kune crystalline state, girazi rinogona kuparadzaniswa.Nokudaro, kubva pakuona kwe thermodynamics, girazi regirazi harina kugadzikana, asi kubva pakuona kwekinetics, yakagadzikana.Kunyangwe iine katsika kekuzvisunungura kupisa kushanduka kuita kristaro ine simba remukati rakaderera, mukana wekushandura kuita crystal state idiki kwazvo patembiricha yekamuri, saka girazi rinenge riri mune metastable state.
(3) Hapana yakagadziriswa nzvimbo yekunyungudika
Shanduko yegorozi zvinhu kubva kuomarara kuenda kumvura kunoitwa mune imwe tembiricha renji (shanduko yetembiricha renji), iyo yakasiyana nekristaro zvinhu uye isina yakagadzika kunyungudika.Kana chinhu chikashandurwa kubva mukunyunguduka kuenda kune chakasimba, kana iri crystallization process, nhanho nyowani dzichaumbwa muhurongwa, uye tembiricha yekristallisation, zvivakwa uye zvimwe zvakawanda zvinochinja nekukurumidza.
Sezvo tembiricha inoderera, viscosity yekunyunguduka inowedzera, uye pakupedzisira girazi rakasimba rinoumbwa.Iyo yekusimbisa maitiro inopedzwa mune yakakura tembiricha renji, uye hapana makristasi matsva anoumbwa.Tembiricha yekuchinja kubva mukunyunguduka kuenda kugirazi rakasimba zvinoenderana nemakemikari egirazi, ayo anowanzo kuchinjika mumakumi kusvika kumazana emadhigirii, saka girazi harina nzvimbo yekunyungudika, asi chete tembiricha yakapfava.Muchikamu ichi, girazi rinoshanduka zvishoma nezvishoma kubva kune viscoplastic kusvika kune viscoelastic.Kuchinja zvishoma nezvishoma kwechivakwa ichi ndiyo hwaro hwegirazi ine yakanaka processability.
(4) Kuenderera mberi uye kudzoka kwekuchinja kwepfuma
Iyo yekuchinja midziyo yegirazi zvinhu kubva pakunyunguduka kuenda kune yakasimba inoenderera uye inodzokororwa, umo mune chikamu chenzvimbo yekushisa chiri epurasitiki, inonzi "shanduko" kana "abnormal" dunhu, umo zvivakwa zvine shanduko yakakosha.
Panyaya yecrystallization, zvivakwa zvinoshanduka sezvinoratidzwa muvhavha ABCD, t.Ndiko kunyungudika kwezvinhu.Kana girazi rinoumbwa ne supercooling, maitiro anochinja sezvakaratidzwa mune abkfe curve.T ndiyo tembiricha yekushanduka kwegirazi, t ndiyo tembiricha inopfava yegirazi.Kune girazi reoxide, viscosity inoenderana neiyi mbiri yakakosha ndeye 101pa · s uye 1005p · s.
Chimiro dzidziso yegirazi rakaputsika
“Glasi chimiro” zvinoreva kugadzwa kwemajiyoni kana maatomu ari muchadenga uye magadzirirwo avanoumba mugirazi.Tsvagiridzo pamusoro pechimiro chegirazi chave kuita basa rinorwadza uye huchenjeri hwemagirazi masayendisiti mazhinji.Kuedza kwekutanga kutsanangura kukosha kwegirazi ndiko g.tamman's supercooled liquid hypothesis, iyo inobata kuti girazi imvura yakanyunguduka, Kuita kwegirazi kusimba kubva pakunyunguduka kusvika kune yakasimba inongova maitiro emuviri, kureva, nekuderera kwekushisa, mamorekuru egirazi anoswedera zvishoma nezvishoma nekuda kwekuderera kwesimba rekinetic. , uye simba rekubatana rinowedzera zvishoma nezvishoma, izvo zvinoita kuti dhigirii yegirazi iwedzere, uye pakupedzisira inoumba dense uye isina kugadzikana yakasimba chinhu.Vanhu vakawanda vakaita basa rakawanda.Mafungiro akanyanya kusimba echimiro chegirazi chemazuva ano ndeichi: theory yechigadzirwa, random network theory, gel theory, five angle symmetry theory, polymer theory zvichingodaro.Pakati pavo, kududzirwa kwakanakisisa kwegirazi ndiyo dzidziso yechigadzirwa uye random network.
Crystal theory
Randell ndakaisa mberi dzidziso yekristaro yechimiro chegirazi muna 1930, nekuti mwenje wemwaranzi yemamwe magirazi wakafanana neiyo yemakristasi ekuumbwa kwakafanana.Akafunga kuti girazi rinoumbwa ne microcrystalline uye amorphous material.Iyo microproduct ine yakajairwa atomu kurongeka uye pachena muganho une amorphous zvinhu.Iyo microproduct saizi ndeye 1.0 ~ 1.5nm, uye zvirimo zvinoverengera zvinopfuura 80%.Iko kutaridzika kwe microcrystalline kwakakanganiswa.Mukufunda kuvharirwa kwesilicate optical glass, Lebedev akaona kuti pakangoerekana pachinja mucurve yegirazi refractive index ine tembiricha pa520 ℃.Akatsanangura chiitiko ichi sekuchinja kwakafanana kwequartz "microcrystalline" mugirazi pa520 ℃.Lebedev aidavira kuti girazi rinoumbwa ne "makristasi" akawanda, akasiyana ne microcrystalline, Shanduko kubva ku "crystal" kuenda kunzvimbo yeamorphous inopedzwa nhanho nhanho, uye hapana muganhu uri pachena pakati pavo.
Nguva yekutumira: May-31-2021