Karbid krem\u00edka (ozna\u010dovan\u00fd aj ako karborundum) je anorganick\u00e1 chemick\u00e1 zl\u00fa\u010denina zlo\u017een\u00e1 z at\u00f3mov krem\u00edka a uhl\u00edka, ktor\u00e1 sa v pr\u00edrode prirodzene vyskytuje ako moissanit a od roku 1893 sa hromadne vyr\u00e1ba na pou\u017eitie ako br\u00fasivo.<\/p>\n
SiC existuje vo viac ako 70 kry\u0161talick\u00fdch form\u00e1ch rozdelen\u00fdch do dvoch polymorfov: alfa karbid krem\u00edka (a-SiC) a beta karbid krem\u00edka (b-SiC). V r\u00e1mci experiment\u00e1lnej chyby sa obe formy topia s\u00fa\u010dasne pri tlakoch do 10 GPa.<\/p>\n
Karbid krem\u00edka je mimoriadne tvrd\u00fd a hust\u00fd materi\u00e1l s mnoh\u00fdmi mo\u017enos\u0165ami pou\u017eitia. N\u00e1jdeme ho vo v\u00fdrobkoch, ako s\u00fa br\u00fasne papiere, br\u00fasne kot\u00fa\u010de, rezn\u00e9 n\u00e1stroje, automobilov\u00e9 komponenty a automobilov\u00e9 \u017eiaruvzdorn\u00e9 materi\u00e1ly; okrem toho sl\u00fa\u017ei ako \u017eiaruvzdorn\u00fd materi\u00e1l v peciach a \u017eiaruvzdorn\u00fdch v\u00fdmurovk\u00e1ch, ako aj ako zrkadlov\u00fd materi\u00e1l v astronomick\u00fdch teleskopoch v\u010faka svojej tvrdosti a n\u00edzkej tepelnej roz\u0165a\u017enosti.<\/p>\n
Edward Goodrich Acheson prv\u00fdkr\u00e1t hromadne vyrobil karbid krem\u00edka v roku 1891, ke\u010f v elektrickej peci zahrieval zmes hliny a pr\u00e1\u0161kov\u00e9ho koksu (uhl\u00edka), pri\u010dom vznikol modro\u010dierny materi\u00e1l zn\u00e1my ako \"karborundum\".<\/p>\n
\u0160t\u00fadie topenia karbidu krem\u00edka pri tlakoch v rozsahu 5-8 GPa odhalili, \u017ee sa top\u00ed zhodne pri v\u0161etk\u00fdch sk\u00faman\u00fdch tlakoch, pri\u010dom jeho krivka topenia m\u00e1 z\u00e1porn\u00fd sklon -44 + 4 K\/GPa, \u010do poskytuje d\u00f4kaz, \u017ee te\u00f3ria funkcion\u00e1lu hustoty ho presne predpovedala.<\/p>\n
Karbid krem\u00edka (SiC) je neoxidov\u00fd keramick\u00fd materi\u00e1l s v\u00fdnimo\u010dn\u00fdmi vlastnos\u0165ami, ktor\u00e9 ho robia u\u017eito\u010dn\u00fdm v mnoh\u00fdch vysokoteplotn\u00fdch aplik\u00e1ci\u00e1ch. SiC je tvrd\u00fd a mimoriadne pevn\u00fd s pevnos\u0165ou polykry\u0161talick\u00e9ho telesa a\u017e 27 GPa; okrem toho m\u00e1 vynikaj\u00face vlastnosti odolnosti proti te\u010deniu spolu s n\u00edzkou tepelnou roz\u0165a\u017enos\u0165ou.<\/p>\n
Keramika z oxidu ceri\u010dit\u00e9ho (CeO2) je nerozpustn\u00e1 vo vode, ale rozpustn\u00e1 v roztaven\u00fdch roztokoch alk\u00e1li\u00ed a \u017eeleza, v\u010faka \u010domu je najtvrd\u0161ia zo v\u0161etk\u00fdch modern\u00fdch kon\u0161truk\u010dn\u00fdch keram\u00edk s odolnos\u0165ou proti oderu, kor\u00f3zii, n\u00e1razom a tepelnej roz\u0165a\u017enosti pri vysok\u00fdch tlakoch; je ide\u00e1lna na pou\u017eitie vo vysokoteplotn\u00fdch aplik\u00e1ci\u00e1ch, ako s\u00fa komponenty jadrov\u00fdch reaktorov.<\/p>\n
Karbid krem\u00edka, \u010dastej\u0161ie ozna\u010dovan\u00fd ako a-SiC, sa be\u017ene nach\u00e1dza v brzd\u00e1ch a spojk\u00e1ch elektrick\u00fdch vozidiel, ako aj v nepriestreln\u00fdch vest\u00e1ch a pou\u017e\u00edva sa aj ako substr\u00e1t pre heterog\u00e9nne katalyz\u00e1tory. Pri v\u00fdrobe priemyseln\u00fdch mno\u017estiev tohto materi\u00e1lu sa st\u00e1le pou\u017e\u00edvaj\u00fa elektrick\u00e9 pece s \u010dist\u00fdm kremi\u010dit\u00fdm pieskom redukovan\u00fdm jemne mlet\u00fdm koksom v elektrickej peci; priemyseln\u00e1 v\u00fdroba karbidu krem\u00edka je na\u010falej ob\u013e\u00fabenou vo\u013ebou pre vysokonap\u00e4\u0165ov\u00e9 aplik\u00e1cie vo v\u00fdkonovej elektronike.<\/p>\n
Karbid krem\u00edka, zn\u00e1my aj ako oxid kremi\u010dit\u00fd, je tvrd\u00e1 chemick\u00e1 zl\u00fa\u010denina zlo\u017een\u00e1 z krem\u00edka a uhl\u00edka, ktor\u00e1 sa prirodzene vyskytuje ako miner\u00e1l moissanit, ale od roku 1893 sa masovo vyr\u00e1ba ako pr\u00e1\u0161ok a kry\u0161t\u00e1l na pou\u017eitie ako abraz\u00edvny materi\u00e1l a materi\u00e1l na v\u00fdrobu nepriestreln\u00fdch keramick\u00fdch dosiek. Ve\u013ek\u00e9 zrn\u00e1 jednotliv\u00fdch kry\u0161t\u00e1lov sa m\u00f4\u017eu sp\u00e1ja\u0165 spekan\u00edm, \u010d\u00edm sa z\u00edskava mimoriadne tvrd\u00e1 \u0161truktur\u00e1lna keramika; okrem toho sa \u010dasto pou\u017e\u00edva na v\u00fdrobu syntetick\u00fdch moissanitov\u00fdch drahokamov zn\u00e1mych ako syntetick\u00e9 moissanitov\u00e9 drahokamy. Karbid krem\u00edka sa tie\u017e spr\u00e1va ako polovodi\u010d; jeho dopovanie dus\u00edkom alebo fosforom z neho m\u00f4\u017ee urobi\u0165 materi\u00e1l typu n; podobne ber\u00fdlium, b\u00f3r alebo hlin\u00edk ho m\u00f4\u017eu zmeni\u0165 na materi\u00e1l typu p v z\u00e1vislosti od toho, ak\u00e9 s\u00fa jeho vlastnosti, dopovanie ho zmen\u00ed na polovodi\u010dov\u00fd materi\u00e1l typu n.<\/p>\n
Karbid krem\u00edka m\u00e1 rozsiahlu p\u00e1smov\u00fa medzeru a vysok\u00fa prierazn\u00fa silu elektrick\u00e9ho po\u013ea, v\u010faka \u010domu je vhodn\u00fd pre elektronick\u00e9 zariadenia pracuj\u00face pri extr\u00e9mne vysok\u00fdch teplot\u00e1ch alebo nap\u00e4tiach. Okrem toho je v\u010faka svojej odolnosti vo\u010di tepeln\u00fdm \u0161okom \u0161iroko vyu\u017e\u00edvan\u00fd. Karbid krem\u00edka existuje v r\u00f4znych jednotkov\u00fdch bunk\u00e1ch (kubick\u00fdch, koso\u0161tvorcov\u00fdch alebo hexagon\u00e1lnych). Ak sa zhutn\u00ed pomocou \u00edlu, m\u00f4\u017ee potla\u010di\u0165 rast kr\u010dkov a z\u00e1rove\u0148 zabr\u00e1ni\u0165 tvorbe SiO2, ktor\u00fd by inak zn\u00ed\u017eil modul pru\u017enosti. V r\u00f4znych \u0161t\u00fadi\u00e1ch sa sk\u00famalo jeho spr\u00e1vanie pri taven\u00ed za vysok\u00e9ho tlaku pomocou ab initio simul\u00e1ci\u00ed molekulovej dynamiky zalo\u017een\u00fdch na simul\u00e1ci\u00e1ch te\u00f3rie funkci\u00ed hustoty.<\/p>\n
Karbid krem\u00edka je mimoriadne tvrd\u00fd a tuh\u00fd keramick\u00fd materi\u00e1l, ktor\u00fd sa vyzna\u010duje vysokou teplotnou odolnos\u0165ou, n\u00edzkym koeficientom tepelnej roz\u0165a\u017enosti a odolnos\u0165ou vo\u010di chemick\u00fdm reakci\u00e1m. Dod\u00e1va sa v r\u00f4znych ve\u013ekostiach a form\u00e1ch vr\u00e1tane granulovanej formy na n\u00e1kup, ako aj do\u0161ti\u010diek, z ktor\u00fdch sa daj\u00fa vyrobi\u0165 zrkadl\u00e1 pre ve\u013ek\u00e9 teleskopy. Met\u00f3dy v\u00fdroby karbidu krem\u00edka siahaj\u00fa od priamej synt\u00e9zy uhl\u00edka a\u017e po chemick\u00e9 naparovanie.<\/p>\n
\u0160t\u00fadie z\u00e1vislosti Debyeho tepl\u00f4t od tlaku v ZB a RS SiC od 3100+40 K do 5-8 GPa s pou\u017eit\u00edm hasiacich experimentov a meran\u00ed in situ sa uskuto\u010dnili pri teplot\u00e1ch od 3100+40 K do 5-8 GPa s pou\u017eit\u00edm hasiacich experimentov a meran\u00ed in situ. V\u00fdsledky ukazuj\u00fa, \u017ee pri tlaku okolia s\u00fa obe Lameho kon\u0161tanty (l, m) kladn\u00e9 s rast\u00facou odch\u00fdlkou m, \u010do nazna\u010duje zv\u00fd\u0161en\u00fa silu necentr\u00e1lnych s\u00edl mnoh\u00fdch telies zah\u0155\u0148aj\u00facich interakcie prenosu n\u00e1boja pri vy\u0161\u0161\u00edch tlakoch, \u010do vedie k mechanickej tuhosti stla\u010dite\u013enosti SiC.<\/p>","protected":false},"excerpt":{"rendered":"
Silicon carbide (also referred to as carborundum) is an inorganic chemical compound composed of silicon and carbon atoms, naturally found […]<\/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":[5],"tags":[],"class_list":["post-66","post","type-post","status-publish","format-standard","hentry","category-product-related"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/siliconcarbideceramic.net\/sk\/wp-json\/wp\/v2\/posts\/66","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/siliconcarbideceramic.net\/sk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/siliconcarbideceramic.net\/sk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/siliconcarbideceramic.net\/sk\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/siliconcarbideceramic.net\/sk\/wp-json\/wp\/v2\/comments?post=66"}],"version-history":[{"count":1,"href":"https:\/\/siliconcarbideceramic.net\/sk\/wp-json\/wp\/v2\/posts\/66\/revisions"}],"predecessor-version":[{"id":67,"href":"https:\/\/siliconcarbideceramic.net\/sk\/wp-json\/wp\/v2\/posts\/66\/revisions\/67"}],"wp:attachment":[{"href":"https:\/\/siliconcarbideceramic.net\/sk\/wp-json\/wp\/v2\/media?parent=66"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/siliconcarbideceramic.net\/sk\/wp-json\/wp\/v2\/categories?post=66"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/siliconcarbideceramic.net\/sk\/wp-json\/wp\/v2\/tags?post=66"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}