Karbid krem\u00edka, \u010dastej\u0161ie ozna\u010dovan\u00fd ako karborundum, je extr\u00e9mne tvrd\u00e1 syntetick\u00e1 kry\u0161talick\u00e1 zl\u00fa\u010denina zlo\u017een\u00e1 z krem\u00edka a uhl\u00edka, ktor\u00e1 sa vyzna\u010duje vysokou tepelnou vodivos\u0165ou, n\u00edzkym koeficientom roz\u0165a\u017enosti, odolnos\u0165ou vo\u010di chemick\u00fdm reakci\u00e1m a polovodi\u010dov\u00fdmi schopnos\u0165ami.<\/p>\n
Moissanit, jeho pr\u00edrodn\u00fd n\u00e1protivok, sa vyskytuje ako miner\u00e1l, ale nach\u00e1dza sa len vo ve\u013emi obmedzenom mno\u017estve v meteoritoch a kimberlitov\u00fdch lo\u017eisk\u00e1ch; preto sa vyr\u00e1ba takmer v\u00fdlu\u010dne synteticky.<\/p>\n
Karbid krem\u00edka (SiC) je tvrd\u00e1 zl\u00fa\u010denina krem\u00edka a uhl\u00edka, ktor\u00e1 sa prirodzene vyskytuje ako miner\u00e1l moissanit v arizonskom meteorickom kr\u00e1teri Canyon Diablo. Edward Acheson za\u010dal masovo vyr\u00e1ba\u0165 SiC v roku 1893 na pou\u017eitie ako priemyseln\u00e9 brusivo, hoci odvtedy sa roz\u0161\u00edrilo jeho pou\u017e\u00edvanie ako z\u00e1kladu dlhotrvaj\u00facich keramick\u00fdch aplik\u00e1ci\u00ed, ako s\u00fa automobilov\u00e9 brzdy\/spojky\/vesty.<\/p>\n
Merania tvrdosti pod\u013ea Mohsovej stupnice ho zara\u010fuj\u00fa medzi najtvrd\u0161ie materi\u00e1ly, ktor\u00e9 \u010dlovek pozn\u00e1, a t\u00fdm sa st\u00e1va jedn\u00fdm z najtvrd\u0161\u00edch materi\u00e1lov. Okrem toho je v\u010faka svojej ve\u013emi vysokej tvrdosti (9 na Mohsovej stupnici) dostato\u010dne odoln\u00fd vo\u010di n\u00e1razom a opotrebovaniu, ako aj odoln\u00fd vo\u010di kor\u00f3zii a v porovnan\u00ed s podobn\u00fdmi materi\u00e1lmi m\u00e1 n\u00edzku tepeln\u00fa vodivos\u0165 a rozp\u00ednavos\u0165. Okrem toho sa v\u010faka dopovaniu b\u00f3rom, ni\u00f3bom alebo hlin\u00edkom st\u00e1va polovodi\u010dov\u00fdm materi\u00e1lom typu p.<\/p>\n
Karbid krem\u00edka m\u00e1 tesn\u00fa \u0161trukt\u00faru pozost\u00e1vaj\u00facu z at\u00f3mov uhl\u00edka a krem\u00edka kovalentne viazan\u00fdch do \u0161tvorat\u00f3mov\u00fdch v\u00e4zieb prostredn\u00edctvom tetraedrick\u00fdch v\u00e4zieb, \u010do z neho rob\u00ed pevn\u00fa l\u00e1tku nerozpustn\u00fa vo vode, alkohole a v\u00e4\u010d\u0161ine organick\u00fdch zl\u00fa\u010den\u00edn, ale rozpustn\u00fa v roztaven\u00fdch z\u00e1sad\u00e1ch a \u017eeleze. SiC je pozoruhodn\u00fd svojimi fascinuj\u00facimi elektrick\u00fdmi vlastnos\u0165ami; odpor sa pohybuje v rozmedz\u00ed viac ako siedmich r\u00e1dov v d\u00f4sledku po\u010detn\u00fdch polytypov pr\u00edtomn\u00fdch v jeho chemickom zlo\u017een\u00ed.<\/p>\n
Karbid krem\u00edka je ve\u013emi odoln\u00fd a vydr\u017e\u00ed vysok\u00fd tlak. Okrem toho jeho teplota topenia presahuje 2 000 \u00b0C a n\u00edzky koeficient tepelnej roz\u0165a\u017enosti ho predur\u010duje na pou\u017eitie pri vysok\u00fdch teplot\u00e1ch.<\/p>\n
Edward Goodrich Acheson bol v roku 1891 priekopn\u00edkom jeho komer\u010dnej v\u00fdroby. Acheson pou\u017eil uhl\u00edk z uhlia ako elektr\u00f3du a zahrieval zmes \u00edlu a pr\u00e1\u0161kov\u00e9ho koksu v \u017eeleznej miske; vznikli jasne zelen\u00e9 kry\u0161t\u00e1ly, ktor\u00e9 boli ve\u013emi tvrd\u00e9 a pripom\u00ednali diamanty; t\u00e1to zl\u00fa\u010denina bola p\u00f4vodne zn\u00e1ma ako karborundum, ale dnes je zn\u00e1ma ako SiC.<\/p>\n
Plast vystu\u017een\u00fd uhl\u00edkov\u00fdmi vl\u00e1knami (CFRP) je neuverite\u013en\u00fd materi\u00e1l a jedna z najtvrd\u0161\u00edch zn\u00e1mych l\u00e1tok, ktorej konkuruj\u00fa len diamant, kubick\u00fd nitrid b\u00f3ru a karbid b\u00f3ru. Uhl\u00edkov\u00e9 vl\u00e1kno s tvrdos\u0165ou pod\u013ea Mohsa 9 sa \u0161iroko pou\u017e\u00edva v najr\u00f4znej\u0161\u00edch oblastiach: mo\u017eno ho n\u00e1js\u0165 ako abraz\u00edvum, napr\u00edklad v br\u00fasnych papieroch a br\u00fasnych kot\u00fa\u010doch, v priemyseln\u00fdch peciach ako \u017eiaruvzdorn\u00fd materi\u00e1l pre pece, ako rezn\u00e9 n\u00e1stroje pre rezacie stoly, a dokonca aj v automobilov\u00fdch brzd\u00e1ch\/spojk\u00e1ch!<\/p>\n
Chemick\u00e1 inertnos\u0165 keramiky umo\u017e\u0148uje odol\u00e1va\u0165 kor\u00f3zii sp\u00f4sobenej r\u00f4znymi chemik\u00e1liami a zachova\u0165 si pevnos\u0165 v \u0161irokom rozsahu tepl\u00f4t. Keramika je tie\u017e neoddelite\u013enou s\u00fa\u010das\u0165ou kompozitn\u00fdch pancierov\u00fdch syst\u00e9mov, ktor\u00e9 s\u00fa \u00fa\u010dinn\u00e9 proti s\u00fa\u010dasn\u00fdm aj nov\u00fdm balistick\u00fdm hrozb\u00e1m, vr\u00e1tane vysoko v\u00fdkonnej \u013eahkej keramiky SiC spolo\u010dnosti Saint-Gobain Performance Ceramics & Refractories, ako je reak\u010dne viazan\u00fd SiC (RBSC), spekan\u00fd SiC a karborundum na toto pou\u017eitie.<\/p>\n
Karbid krem\u00edka je vo svojej naj\u010distej\u0161ej forme zvy\u010dajne izolant, ale po pridan\u00ed pr\u00edmes\u00ed alebo dopovania m\u00f4\u017ee vykazova\u0165 polovodiv\u00e9 vlastnosti. Okrem toho m\u00e1 tento materi\u00e1l vynikaj\u00face trvanliv\u00e9 vlastnosti pre vysokoteplotn\u00e9 aplik\u00e1cie; okrem toho sa m\u00f4\u017ee pochv\u00e1li\u0165 n\u00edzkym prierezom neutr\u00f3nov a vlastnos\u0165ami odolnosti vo\u010di po\u0161kodeniu \u017eiaren\u00edm.<\/p>\n
Tepeln\u00e1 vodivos\u0165 SiC z\u00e1vis\u00ed od jeho \u0161trukt\u00fary a ve\u013ekosti kry\u0161t\u00e1lu. Tak ako u v\u00e4\u010d\u0161iny pevn\u00fdch l\u00e1tok, jeho tepeln\u00e1 vodivos\u0165 sa zvy\u0161uje s teplotou. Monokry\u0161talick\u00fd SiC m\u00e1 vysok\u00fa tepeln\u00fa vodivos\u0165, zatia\u013e \u010do polykry\u0161talick\u00fd SiC m\u00e1 zvy\u010dajne ni\u017e\u0161ie hodnoty v d\u00f4sledku n\u00e1hodn\u00e9ho rozlo\u017eenia z\u0155n, ktor\u00e9 prispievaj\u00fa k efektom povrchov\u00e9ho rozptylu.<\/p>\n
Karbid krem\u00edka sa vyr\u00e1ba v r\u00f4znych polymorfoch, pri\u010dom najzn\u00e1mej\u0161ou verziou je alfa karbid krem\u00edka (a-SiC). A-SiC sa vyzna\u010duje hexagon\u00e1lnou kry\u0161t\u00e1lovou \u0161trukt\u00farou podobnou tej, ktor\u00e1 sa vyskytuje vo wurtzite; beta modifik\u00e1cia b-SiC sa vyzna\u010duje kry\u0161t\u00e1lovou \u0161trukt\u00farou zinkovej blende podobnou diamantu a menej \u010dasto sa vyskytuj\u00face formy m\u00f4\u017eu dokonca sl\u00fa\u017ei\u0165 ako materi\u00e1ly na podporu katalyz\u00e1torov.<\/p>\n
Najnov\u0161ie SEM sn\u00edmky a-SiC aj b-SiC boli zozbieran\u00e9 s cie\u013eom presk\u00fama\u0165, ako proces synt\u00e9zy ovplyvnil ich mikro\u0161trukt\u00faru a tepeln\u00fa vodivos\u0165. V\u00fdsledky uk\u00e1zali, \u017ee tepeln\u00e1 vodivos\u0165 a-SiC kles\u00e1 s rast\u00facou ve\u013ekos\u0165ou kr\u010dka, \u010do nazna\u010duje, \u017ee pr\u00ed\u010dinou je dif\u00fazny povrchov\u00fd rozptyl. Naopak, tepeln\u00e1 vodivos\u0165 b-SiC sa s ve\u013ekos\u0165ou hrdla zvy\u0161ovala; tento trend zodpoved\u00e1 predpovediam Callaway-Hollandovho modelu teplotnej z\u00e1vislosti tepelnej vodivosti fonick\u00fdch kry\u0161t\u00e1lov.<\/p>\n
Karbid krem\u00edka, tvrd\u00e1 chemick\u00e1 zl\u00fa\u010denina zlo\u017een\u00e1 z oxidu kremi\u010dit\u00e9ho a uhl\u00edka, sa \u0161iroko pou\u017e\u00edva ako abraz\u00edvum v lapid\u00e1rnom a priemyselnom prostred\u00ed, napr\u00edklad pri pieskovan\u00ed, br\u00fasen\u00ed kot\u00fa\u010dmi, rezan\u00ed vodn\u00fdm l\u00fa\u010dom a pieskovan\u00ed. Tento \u017eiaruvzdorn\u00fd materi\u00e1l s extr\u00e9mne odolnou tvrdos\u0165ou 9 pod\u013ea Mohsa sa \u010dasto pou\u017e\u00edva aj na \u017eiaruvzdorn\u00e9 oblo\u017eenia, vykurovacie teles\u00e1 a d\u00fdzy hor\u00e1kov. Okrem toho karbid krem\u00edka zost\u00e1va chemicky inertn\u00fd a odoln\u00fd vo\u010di kor\u00f3zii aj vo\u010di kyselin\u00e1m chlorovod\u00edkov\u00fdm, s\u00edrov\u00fdm a fluorovod\u00edkov\u00fdm.<\/p>\n
Z elektrick\u00e9ho h\u013eadiska je SiC v \u010distom stave zvy\u010dajne izolant, av\u0161ak s ur\u010dit\u00fdmi pr\u00eddavkami alebo dopingov\u00fdmi l\u00e1tkami m\u00f4\u017ee vykazova\u0165 polovodi\u010dov\u00e9 vlastnosti, ako je napr\u00edklad vodivos\u0165 n-typu prostredn\u00edctvom zdie\u013eania elektr\u00f3nov\u00fdch p\u00e1rov v r\u00e1mci tetraedrickej kovalentnej v\u00e4zbovej \u0161trukt\u00fary prostredn\u00edctvom tzv. sp3 hybridn\u00fdch orbit\u00e1lov.<\/p>\n
Monokry\u0161t\u00e1ly SiC s vn\u00fatornou vodivos\u0165ou pribli\u017ene 3,1 +-0,2 eV maj\u00fa vy\u0161\u0161iu vodivos\u0165 ako \u010dist\u00fd krem\u00edk alebo nitrid g\u00e1lia, \u010do nazna\u010duje, \u017ee by mohli poskytova\u0165 lep\u0161iu elektrick\u00fa vodivos\u0165 pre elektrick\u00e9 aplik\u00e1cie.<\/p>\n
V\u00fdrobky z karbidu krem\u00edka spolo\u010dnosti Henan Superior Abrasives s\u00fa ide\u00e1lnou vo\u013ebou na pou\u017eitie v elektronick\u00fdch zariadeniach v\u010faka svojej vynikaj\u00facej odolnosti vo\u010di nap\u00e4tiu - 10-kr\u00e1t vy\u0161\u0161ej ako pri be\u017enom krem\u00edku a vy\u0161\u0161ej ako pri nitride g\u00e1lia! Okrem toho na\u0161a \u0161k\u00e1la vysokokvalitn\u00fdch karbidov krem\u00edka vykazuje vynikaj\u00face vlastnosti odolnosti vo\u010di oxid\u00e1cii a tepeln\u00fdm \u0161okom, v\u010faka ktor\u00fdm je tento materi\u00e1l ide\u00e1lny na pou\u017eitie v elektronick\u00fdch zariadeniach. Ke\u010f\u017ee n\u00e1m le\u017e\u00ed na srdci spokojnos\u0165 z\u00e1kazn\u00edkov a dokonalos\u0165, m\u00f4\u017eete sa od n\u00e1s spo\u013eahn\u00fa\u0165 len na to najlep\u0161ie! Zavolajte n\u00e1m teraz a zistite viac inform\u00e1ci\u00ed o na\u0161ich v\u00fdrobkoch! Kontaktujte n\u00e1s teraz a dozviete sa viac!<\/p>","protected":false},"excerpt":{"rendered":"
Silicon carbide, more commonly referred to as carborundum, is an extremely hard synthetic crystalline compound made up of silicon and carbon characterized by high thermal conductivity, low coefficient of expansion, resistance to chemical reaction and semiconducting capabilities. Moissanite, its natural counterpart, occurs as a mineral but can only be found in very limited amounts in […]<\/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-352","post","type-post","status-publish","format-standard","hentry","category-knowledge"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/posts\/352","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=352"}],"version-history":[{"count":1,"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/posts\/352\/revisions"}],"predecessor-version":[{"id":353,"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/posts\/352\/revisions\/353"}],"wp:attachment":[{"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/media?parent=352"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/categories?post=352"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/tags?post=352"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}