Karbid krem\u00edka (SiC) je ve\u013emi tvrd\u00fd syntetick\u00fd materi\u00e1l, ktor\u00fd prv\u00fdkr\u00e1t syntetizoval Edward Acheson v roku 1891 v peci zahriatej uhl\u00edkom a oxidom hlinit\u00fdm. Od jeho uvedenia do priemyslu ako priemyseln\u00e9ho abraz\u00edva v 20. rokoch 20. storo\u010dia sa SiC r\u00fdchlo stal jedn\u00fdm z najvyh\u013ead\u00e1vanej\u0161\u00edch materi\u00e1lov vo ve\u013ekom meradle.<\/p>\n
SiC sa dod\u00e1va v r\u00f4znych kry\u0161t\u00e1lov\u00fdch \u0161trukt\u00farach zn\u00e1mych ako polytypy; pre aplik\u00e1cie s vysok\u00fdm v\u00fdkonom je najlep\u0161\u00ed polytyp s hexagon\u00e1lnou at\u00f3movou \u0161trukt\u00farou 4H-SiC.<\/p>\n
Karbid krem\u00edka je jemn\u00e1 keramika s rozmanit\u00fdmi fyzik\u00e1lnymi vlastnos\u0165ami, ktor\u00e9 z nej robia jeden z najv\u0161estrannej\u0161\u00edch \u017eiaruvzdorn\u00fdch materi\u00e1lov na trhu. Od jeho pevnosti, tvrdosti, odolnosti proti kor\u00f3zii a vysok\u00e9ho bodu tavenia a\u017e po jeho v\u0161estrannos\u0165 v extr\u00e9mnych technick\u00fdch aplik\u00e1ci\u00e1ch - ako s\u00fa lo\u017eisk\u00e1 \u010derpadiel, ventily, pieskovacie vstrekova\u010de a lisovacie formy - karbid krem\u00edka sa osved\u010dil ako d\u00f4le\u017eit\u00fd prvok pre modern\u00e9 elektronick\u00e9 zariadenia. Okrem t\u00fdchto p\u00f4sobiv\u00fdch mechanick\u00fdch vlastnost\u00ed pon\u00faka karbid krem\u00edka ako nepostr\u00e1date\u013en\u00e1 zlo\u017eka v\u00fdznamn\u00e9 polovodi\u010dov\u00e9 schopnosti.<\/p>\n
\u010cist\u00fd karbid krem\u00edka je bezfarebn\u00e1 kry\u0161talick\u00e1 l\u00e1tka s hustotou 3,21 g\/ml a teplotou topenia vy\u0161\u0161ou ako 2700 \u00b0C. \u010casto sa vyr\u00e1ba Achesonov\u00fdm procesom, pri ktorom sa kremi\u010dit\u00fd piesok a koks kombinuj\u00fa a zahrievaj\u00fa na vysok\u00e9 teploty v elektrickej peci, a\u017e k\u00fdm sa kremi\u010dit\u00fd piesok neskarbonizuje a nevytvor\u00ed hrubokry\u0161talick\u00e9 \u0161trukt\u00fary, ako je a-SiC, zatia\u013e \u010do pri b-SiC ingotoch sa vytv\u00e1raj\u00fa diamantov\u00e9 kubick\u00e9 \u0161trukt\u00fary.<\/p>\n
Alfa-SiC je naj\u010dastej\u0161ie sa vyskytuj\u00faci polymorf karbidu krem\u00edka s hexagon\u00e1lnou kry\u0161t\u00e1lovou \u0161trukt\u00farou podobnou wurtzitu. Beta-SiC formy s diamantovou kubickou kry\u0161t\u00e1lovou \u0161trukt\u00farou sa naj\u010dastej\u0161ie vyskytuj\u00fa v meteoritoch; okrem toho sa t\u00e1to forma \u010dasto vyskytuje v priemyselnej v\u00fdrobe pri procesoch tavenia a odlievania na v\u00fdrobu r\u00f4znych v\u00fdrobkov.<\/p>\n
Karbid krem\u00edka je h\u00fa\u017eevnat\u00e1 neoxidov\u00e1 keramika s pozoruhodn\u00fdmi fyzik\u00e1lnymi a chemick\u00fdmi vlastnos\u0165ami: vysokou tvrdos\u0165ou a tuhos\u0165ou, n\u00edzkou tepelnou roz\u0165a\u017enos\u0165ou a v\u00fdnimo\u010dnou odolnos\u0165ou proti kor\u00f3zii. Okrem toho je v\u010faka svojmu \u0161irok\u00e9mu p\u00e1smov\u00e9mu rozhraniu vhodn\u00fd na aplik\u00e1cie vo vysokov\u00fdkonnej elektronike.<\/p>\n
Voda, alkohol a v\u00e4\u010d\u0161ina kysel\u00edn s v\u00fdnimkou kyseliny fluorovod\u00edkovej a fluoridov kysel\u00edn ju nerozp\u00fa\u0161\u0165aj\u00fa, \u010do zabezpe\u010duje lep\u0161iu chemick\u00fa stabilitu v porovnan\u00ed s v\u00e4\u010d\u0161inou ostatn\u00fdch \u017eiaruvzdorn\u00fdch keram\u00edk.<\/p>\n
Karbid krem\u00edka prv\u00fdkr\u00e1t umelo syntetizoval Edward Acheson v roku 1891 ako n\u00e1hodn\u00fd ved\u013eaj\u0161\u00ed produkt elektricky zahrievanej taveniny uhl\u00edka a oxidu hlinit\u00e9ho a stal sa jednou z najd\u00f4le\u017eitej\u0161\u00edch priemyseln\u00fdch keram\u00edk na svete, ktor\u00e1 sa pou\u017e\u00edva ako abraz\u00edvny materi\u00e1l pre oce\u013eov\u00e9 zliatiny, ako aj ako kon\u0161truk\u010dn\u00e1 keramika.<\/p>\n
Karbid krem\u00edka m\u00e1 tesn\u00e9 tetraedrick\u00e9 usporiadanie kovalentne viazan\u00e9. R\u00f4zne postupnosti usporiadania d\u00e1vaj\u00fa vznikn\u00fa\u0165 r\u00f4znym polytypom - ka\u017ed\u00fd z nich sa vyzna\u010duje odli\u0161n\u00fdmi fyzik\u00e1lnymi a chemick\u00fdmi vlastnos\u0165ami.<\/p>\n
Alfa forma (a-SiC) m\u00e1 hexagon\u00e1lnu kry\u0161t\u00e1lov\u00fa \u0161trukt\u00faru podobn\u00fa wurtzitu, zatia\u013e \u010do jej beta verzia (b-SiC) vykazuje kry\u0161t\u00e1lov\u00fa \u0161trukt\u00faru zinku blende podobn\u00fa diamantu. Obe odrody SiC sa daj\u00fa \u013eahko opracova\u0165 len s obmedzen\u00fdmi obmedzeniami tvrdosti a br\u00fasi\u0165 do r\u00f4znych tvarov na pou\u017eitie ako br\u00fasne v\u00fdrobky alebo zrkadl\u00e1 v teleskopoch, ktor\u00e9 s\u00fa popul\u00e1rnymi aplik\u00e1ciami t\u00fdchto materi\u00e1lov.<\/p>\n
Karbid krem\u00edka je polovodi\u010dov\u00fd materi\u00e1l, \u010do znamen\u00e1, \u017ee vykazuje niektor\u00e9 vlastnosti, ktor\u00e9 sa vyskytuj\u00fa v kovoch (ktor\u00e9 ved\u00fa elektrick\u00fd pr\u00fad) aj nekovoch, ako s\u00fa izolanty (ktor\u00e9 odol\u00e1vaj\u00fa toku elektrick\u00e9ho pr\u00fadu). Presn\u00e1 povaha jeho elektrick\u00fdch vlastnost\u00ed z\u00e1vis\u00ed od teploty a ak\u00fdchko\u013evek ne\u010dist\u00f4t pr\u00edtomn\u00fdch v jeho kry\u0161t\u00e1lovej \u0161trukt\u00fare - pri ni\u017e\u0161\u00edch teplot\u00e1ch sa spr\u00e1va sk\u00f4r ako izolant, ktor\u00fd sa br\u00e1ni toku elektriny, zatia\u013e \u010do pri vy\u0161\u0161\u00edch teplot\u00e1ch sa st\u00e1va sk\u00f4r vodi\u010dom a umo\u017e\u0148uje, aby n\u00edm elektrina prech\u00e1dzala.<\/p>\n
Kry\u0161t\u00e1lov\u00e1 \u0161trukt\u00fara SiC pozost\u00e1va z vrstiev zlo\u017een\u00fdch z at\u00f3mov krem\u00edka a uhl\u00edka viazan\u00fdch v tetraedrick\u00fdch konfigur\u00e1ci\u00e1ch. Tieto tesne usporiadan\u00e9 vrstvy vytv\u00e1raj\u00fa tesn\u00fa \u0161trukt\u00faru, ktor\u00e1 d\u00e1va vznikn\u00fa\u0165 r\u00f4znym kry\u0161t\u00e1lov\u00fdm \u0161trukt\u00faram naz\u00fdvan\u00fdm polytypy; ka\u017ed\u00fd polytyp m\u00e1 rovnak\u00e9 chemick\u00e9 zlo\u017eenie, ale odli\u0161n\u00fa kry\u0161t\u00e1lov\u00fa \u0161trukt\u00faru, ktor\u00e1 ovplyv\u0148uje jeho elektrick\u00e9 vlastnosti. Postupnos\u0165 ukladania vrstiev ka\u017ed\u00e9ho polytypu m\u00f4\u017ee vytv\u00e1ra\u0165 kubick\u00e9, hexagon\u00e1lne alebo romboedrick\u00e9 kry\u0161t\u00e1lov\u00e9 \u0161trukt\u00fary.<\/p>\n
SiC je atrakt\u00edvny materi\u00e1l pre vysokonap\u00e4\u0165ov\u00e9 v\u00fdkonov\u00e9 zariadenia v\u010faka svojej tetraedrickej kry\u0161t\u00e1lovej \u0161trukt\u00fare a \u0161irokej medzere v elektronickom p\u00e1sme, \u010do ho rob\u00ed obzvl\u00e1\u0161\u0165 vhodn\u00fdm pre di\u00f3dy a tranzistory. \u0160ir\u0161ia elektronick\u00e1 p\u00e1smov\u00e1 medzera SiC mu umo\u017e\u0148uje odol\u00e1va\u0165 vy\u0161\u0161\u00edm prierazn\u00fdm elektrick\u00fdm poliam ako krem\u00edk a z\u00e1rove\u0148 m\u00e1 men\u0161ie sp\u00ednacie straty, ktor\u00e9 pom\u00e1haj\u00fa zvy\u0161ova\u0165 energetick\u00fa \u00fa\u010dinnos\u0165. Okrem toho mo\u017eno vodivos\u0165 p\u00f3rovit\u00e9ho karbidu krem\u00edka modifikova\u0165 jeho dopovan\u00edm pr\u00edmesami, aby sa dosiahla vy\u0161\u0161ia vodivos\u0165 aj nap\u00e4\u0165ov\u00e1 schopnos\u0165 na pou\u017eitie v \u00fa\u010dinn\u00fdch meni\u010doch energie pre meni\u010de energie elektrick\u00fdch vozidiel.<\/p>\n
Karbid krem\u00edka je mimoriadne tvrd\u00fd, chemicky inertn\u00fd materi\u00e1l, ktor\u00fd sa v pr\u00edrode vyskytuje ako \u010dierne diamanty s tvrdos\u0165ou pod\u013ea Mohsa 9. M\u00e1 mnoho v\u00fdhodn\u00fdch vlastnost\u00ed vr\u00e1tane teplotnej stability, n\u00edzkej tepelnej roz\u0165a\u017enosti a odolnosti vo\u010di chemick\u00fdm vplyvom, v\u010faka \u010domu je ide\u00e1lny ako polovodi\u010dov\u00fd materi\u00e1l.<\/p>\n
Oxid l\u00edtny je v\u00fdnimo\u010dn\u00fd elektrick\u00fd izolant s v\u00fdnimo\u010dn\u00fdm faktorom nap\u00e4\u0165ovej odolnosti, ktor\u00fd je desa\u0165kr\u00e1t v\u00e4\u010d\u0161\u00ed ako u krem\u00edka, \u010do z neho rob\u00ed \u010doraz atrakt\u00edvnej\u0161iu mo\u017enos\u0165 ako n\u00e1hradn\u00fd materi\u00e1l krem\u00edka pre v\u00fdkonov\u00fa elektroniku a in\u00e9 vysoko v\u00fdkonn\u00e9 aplik\u00e1cie.<\/p>\n
SiC sa vyr\u00e1ba pomocou r\u00f4znych polymorfn\u00fdch kry\u0161t\u00e1lov\u00fdch \u0161trukt\u00far, z ktor\u00fdch ka\u017ed\u00e1 m\u00e1 svoje \u0161pecifick\u00e9 usporiadanie at\u00f3mov. Vyr\u00e1baj\u00fa sa tri be\u017en\u00e9 polytypy SiC: 3C-SiC, 4H-SiC a 6H-SiC; l\u00ed\u0161ia sa porad\u00edm ukladania vrstiev, \u010do vedie k odli\u0161n\u00fdm fyzik\u00e1lnym a mechanick\u00fdm vlastnostiam.<\/p>\n
Ned\u00e1vny v\u00fdskum uskuto\u010dnen\u00fd na jednotliv\u00fdch SiC nanodr\u00f4toch s r\u00f4znymi pomermi obsadenia \u0161trukt\u00fary ODD bol in-situ testovan\u00fd v \u0165ahu pomocou SEM na pos\u00fadenie ich pevnosti a pru\u017enosti, modul pru\u017enosti v \u0161myku, v\u00fdpo\u010dty Poissonovho pomeru ka\u017edej f\u00e1zy, anal\u00fdza mechanickej anizotropie odhalila, \u017ee Pm-SiC m\u00e1 silnej\u0161ie spr\u00e1vanie v \u0161myku v porovnan\u00ed s b-SiC a Pnnm-SiC NWs; okrem toho pevnos\u0165 r\u00e1stla so zvy\u0161uj\u00facim sa pomerom obsadenia ODD a\u017e do dosiahnutia 32,6%, kde pevnos\u0165 za\u010dala exponenci\u00e1lne klesa\u0165.<\/p>","protected":false},"excerpt":{"rendered":"
Silicon carbide (SiC) is an ultrahard synthetic material first synthesized in 1891 by Edward Acheson in a furnace heated with carbon and alumina. Since its release into industry as an industrial abrasive in the 1920s, SiC has quickly become one of the most sought-after materials on a large scale. SiC comes in various crystal structures […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-gradient":""}},"footnotes":""},"categories":[64],"tags":[],"class_list":["post-335","post","type-post","status-publish","format-standard","hentry","category-knowledge"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/posts\/335","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/comments?post=335"}],"version-history":[{"count":1,"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/posts\/335\/revisions"}],"predecessor-version":[{"id":336,"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/posts\/335\/revisions\/336"}],"wp:attachment":[{"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/media?parent=335"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/categories?post=335"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/tags?post=335"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}