![\"reak\u010dne](\"http:\/\/siliconcarbideceramic.net\/wp-content\/uploads\/2024\/02\/reaction-bonded-sic.jpg\")
<\/p>","protected":false},"excerpt":{"rendered":"Karbid krem\u00edka patr\u00ed medzi najtvrd\u0161ie a najodolnej\u0161ie modern\u00e9 keramick\u00e9 materi\u00e1ly, ktor\u00e9 sa vyu\u017e\u00edvaj\u00fa jednak pre svoju tvrdos\u0165 ako br\u00fasny materi\u00e1l, jednak pre tepeln\u00fa odolnos\u0165 a n\u00edzky koeficient tepelnej roz\u0165a\u017enosti v \u017eiaruvzdorn\u00fdch materi\u00e1loch a keramick\u00fdch aplik\u00e1ci\u00e1ch.<\/p>\n
Moissanit sa m\u00f4\u017ee vyskytova\u0165 aj v pr\u00edrode ako prieh\u013eadn\u00fd miner\u00e1l moissanit. Prv\u00e9 umelo syntetizovan\u00e9 vzorky vznikli v roku 1891 po\u010das pokusov Edwarda Achesona o vytvorenie umel\u00fdch diamantov; nesk\u00f4r umelo syntetizoval \u010fal\u0161ie vzorky chemik Henri Moissan, nosite\u013e Nobelovej ceny.<\/p>\n
Karbid krem\u00edka (SiC) je mimoriadne pevn\u00e1 neoxidov\u00e1 keramika, ktor\u00e1 pon\u00faka v\u00fdnimo\u010dn\u00fa odolnos\u0165 proti kor\u00f3zii a chemick\u00e9mu p\u00f4sobeniu pri zv\u00fd\u0161en\u00fdch teplot\u00e1ch. SiC sa vyu\u017e\u00edva ako \u017eiaruvzdorn\u00fd obkladov\u00fd materi\u00e1l v priemyseln\u00fdch peciach, ako aj v br\u00fasnych kot\u00fa\u010doch, rezn\u00fdch n\u00e1strojoch a v aplik\u00e1ci\u00e1ch, kde je pevnos\u0165 k\u013e\u00fa\u010dov\u00e1, napr\u00edklad v br\u00fasnych kot\u00fa\u010doch, rezn\u00fdch n\u00e1strojoch a pri obr\u00e1ban\u00ed. Okrem toho s\u00fa komponenty z SiC k\u013e\u00fa\u010dov\u00fdmi s\u00fa\u010das\u0165ami odporov\u00fdch vykurovac\u00edch prvkov, termistorov pre elektrick\u00e9 pece, ako aj v\u00fdstelkov\u00fdch r\u00farok a tesniacich pl\u00f4ch obsahuj\u00facich SiC.<\/p>\n
SiC je zn\u00e1my svojou vynikaj\u00facou tepelnou odolnos\u0165ou a pevnos\u0165ou pri zv\u00fd\u0161en\u00fdch teplot\u00e1ch, v\u010faka \u010domu je ve\u013emi cenen\u00fd v priemyseln\u00fdch aplik\u00e1ci\u00e1ch. SiC odol\u00e1va oxid\u00e1cii pri teplot\u00e1ch a\u017e do 1000 \u00b0C vytv\u00e1ran\u00edm ochrann\u00e9ho oxidov\u00e9ho povlaku, ktor\u00fd p\u00f4sob\u00ed ako bari\u00e9ra medzi jeho povrchmi a prvkami, ktor\u00e9 obklopuje; pri vy\u0161\u0161\u00edch teplot\u00e1ch v\u0161ak m\u00f4\u017eu trhliny prenikn\u00fa\u0165 cez t\u00fato bari\u00e9ru a odv\u00e1dza\u0165 energiu cez medzikry\u0161talick\u00e9 alebo zrnit\u00e9 oblasti, \u010do sp\u00f4sobuje \u0165a\u017ekosti so zvy\u0161ovan\u00edm pevnosti pri zv\u00fd\u0161en\u00fdch teplot\u00e1ch.<\/p>\n
Karbid krem\u00edka sa d\u00e1 vyr\u00e1ba\u0165 dvoma odli\u0161n\u00fdmi postupmi: reak\u010dn\u00fdm sp\u00e1jan\u00edm a spekan\u00edm. Obe formy maj\u00fa v\u00fdznamn\u00fd vplyv na jeho mikrostrukt\u00faru, a t\u00fdm aj na jeho vlastnosti pri zv\u00fd\u0161en\u00fdch teplot\u00e1ch. Reak\u010dn\u00e9 sp\u00e1janie spo\u010d\u00edva v infiltr\u00e1cii surov\u00fdch lisovancov, zlo\u017een\u00fdch zo zmes\u00ed SiC a uhl\u00edka, tekut\u00fdm krem\u00edkom; t\u00fdm vznikaj\u00fa \u0161trukt\u00fary s minim\u00e1lnou zmenou rozmerov po\u010das spracovania a s rozsiahlou povrchovou plochou. \u017diaruvzdorn\u00e1 mikrostrukt\u00fara typu \u201ecore-shell\u201c poskytuje jedine\u010dn\u00e9 vlastnosti, o ktor\u00fdch sa preuk\u00e1zalo, \u017ee zvy\u0161uj\u00fa pevnos\u0165 SiC pri zv\u00fd\u0161en\u00fdch teplot\u00e1ch.<\/p>\n
V\u010faka svojej pozoruhodnej pevnosti je karbid krem\u00edka vynikaj\u00facou vo\u013ebou materi\u00e1lu pre vysokoteplotn\u00e9 aplik\u00e1cie, ako s\u00fa napr\u00edklad keramick\u00e9 brzdov\u00e9 do\u0161ti\u010dky pre osobn\u00e9 automobily. Tento materi\u00e1l je schopn\u00fd odol\u00e1va\u0165 teplot\u00e1m a\u017e do 1400 \u00b0C a pritom si zachov\u00e1va svoju v\u00fdnimo\u010dn\u00fa pevnos\u0165 a tvrdos\u0165, \u010do z neho rob\u00ed ide\u00e1lny materi\u00e1l.<\/p>\n
Karbid krem\u00edka sa od ostatn\u00fdch keramick\u00fdch materi\u00e1lov odli\u0161uje t\u00fdm, \u017ee sa pri vysok\u00fdch teplot\u00e1ch nerozklad\u00e1 ani netav\u00ed, v\u010faka \u010domu je vhodn\u00fd na pou\u017eitie v aplik\u00e1ci\u00e1ch s vysok\u00fdm nam\u00e1han\u00edm a za\u0165a\u017een\u00edm, ako s\u00fa lo\u017eisk\u00e1 a nepriestreln\u00e9 platne, bez toho, aby do\u0161lo k trval\u00e9mu po\u0161kodeniu \u0161trukt\u00fary. V\u010faka tomu je karbid krem\u00edka obzvl\u00e1\u0161\u0165 ide\u00e1lny pre aplik\u00e1cie s vysok\u00fdm za\u0165a\u017een\u00edm, ako s\u00fa lo\u017eisk\u00e1 a nepriestreln\u00e9 platne.<\/p>\n
Karbid krem\u00edka sa v pr\u00edrode vyskytuje ako mimoriadne vz\u00e1cny miner\u00e1l moissanit, zatia\u013e \u010do v\u00fdroba syntetick\u00e9ho karbidu krem\u00edka uspokojuje potreby modern\u00e9ho obrann\u00e9ho priemyslu, jadrovej energetiky, kozmickej techniky a leteck\u00e9ho a kozmick\u00e9ho priemyslu, ktor\u00e9 vy\u017eaduj\u00fa presn\u00e9 rozmery.<\/p>\n
Spe\u010den\u00fd karbid krem\u00edka sa p\u00fd\u0161i jednou z najvy\u0161\u0161\u00edch hodn\u00f4t tepelnej vodivosti spomedzi technick\u00fdch keram\u00edk, pri\u010dom ho predstihuje u\u017e len nitrid hlin\u00edka. Toto mo\u017eno prip\u00edsa\u0165 jeho mrie\u017ekovej \u0161trukt\u00fare s kysl\u00edkom, ktor\u00e1 sp\u00f4sobuje v\u00fdrazn\u00e9 rozptylovanie fon\u00f3nov. Hoci je mo\u017en\u00e9 jeho tepeln\u00fa vodivos\u0165 \u010falej zv\u00fd\u0161i\u0165 pou\u017eit\u00edm oxidov\u00fdch pr\u00edsad v procesoch spekania, ich mno\u017estvo by sa malo obmedzi\u0165 na absol\u00fatne minimum, aby sa zachovala \u0161truktur\u00e1lna stabilita a odolnos\u0165 materi\u00e1lu vo\u010di oxid\u00e1cii.<\/p>\n
V\u010faka n\u00edzkej hodnote koeficientu tepelnej roz\u0165a\u017enosti je karbid krem\u00edka ide\u00e1lnym materi\u00e1lom na pou\u017eitie v kompozitoch s keramickou matricou (CMC) v n\u00e1ro\u010dn\u00fdch podmienkach, \u010do vedie k jeho \u010dast\u00e9mu vyu\u017e\u00edvaniu v aplik\u00e1ci\u00e1ch, ako s\u00fa plynov\u00e9 turb\u00edny a trysky raketov\u00fdch motorov, kde musia materi\u00e1ly odol\u00e1va\u0165 vysok\u00fdm teplot\u00e1m aj teplotn\u00fdm \u0161okom.<\/p>\n
V\u010faka odolnosti proti kor\u00f3zii je nehrdzavej\u00faca oce\u013e vynikaj\u00facou vo\u013ebou materi\u00e1lu pre v\u00fdstelky priemyseln\u00fdch pec\u00ed v chemickom priemysle, kde dok\u00e1\u017ee odol\u00e1va\u0165 extr\u00e9mnym teplot\u00e1m a z\u00e1rove\u0148 si zachov\u00e1va\u0165 svoju kon\u0161truk\u010dn\u00fa integritu. Okrem toho nehrdzavej\u00faca oce\u013e pon\u00faka vynikaj\u00facu chemick\u00fa stabilitu, \u010do umo\u017e\u0148uje dlhodob\u00fa prev\u00e1dzku v agres\u00edvnych kvapaln\u00fdch prostrediach, ako s\u00fa kysl\u00e9 a z\u00e1sadit\u00e9 roztoky.<\/p>\n
Najroz\u0161\u00edrenej\u0161\u00ed polymorf karbidu krem\u00edka, alfa forma, sa vyskytuje pri teplot\u00e1ch nad 1700 \u00b0C s kry\u0161t\u00e1lovou \u0161trukt\u00farou typu wurtzitu a bodom topenia nad 1700 \u00b0C. Existuje v\u0161ak aj zriedkavej\u0161ia beta forma s kry\u0161t\u00e1lovou \u0161trukt\u00farou zinkblendy, podobnou diamantu, a ni\u017e\u0161\u00edm bodom topenia 1030 \u00b0C \u2013 t\u00e1to zriedkavej\u0161ia forma m\u00f4\u017ee sl\u00fa\u017ei\u0165 ako nosi\u010d pre heterog\u00e9nne katalyz\u00e1tory.<\/p>\n
Karbid krem\u00edka sa vyskytuje ako por\u00e9zna, tak aj hust\u00e1 keramika. V\u00fdrobn\u00e9 techniky sa zna\u010dne l\u00ed\u0161ia a kone\u010dn\u00e1 mikrostrukt\u00fara z\u00e1vis\u00ed od pou\u017eitej v\u00fdrobnej met\u00f3dy. Reak\u010dne viazan\u00fd SiC sa vyr\u00e1ba infiltr\u00e1ciou lisovan\u00fdch telies zo zmesi uhl\u00edka a SiC roztaven\u00fdm krem\u00edkom, ktor\u00e9 spolu reaguj\u00fa a vytv\u00e1raj\u00fa \u010fal\u0161\u00ed SiC, \u010d\u00edm sa spoja p\u00f4vodn\u00e9 lisovan\u00e9 teles\u00e1; spekan\u00fd SiC, ako napr\u00edklad Hexoloy, sa vytv\u00e1ra prostredn\u00edctvom be\u017en\u00fdch keramick\u00fdch formovac\u00edch procesov a n\u00e1sledne sa spek\u00e1 pri vysok\u00fdch teplot\u00e1ch v inertnej atmosf\u00e9re.<\/p>\n
Tvrdos\u0165 karbidu krem\u00edka na Mohsovej stupnici dosahuje hodnotu a\u017e 9,5, \u010d\u00edm sa zara\u010fuje na tretie miesto hne\u010f za diamantom a nitridom b\u00f3ru. V\u010faka tomu je vhodn\u00fd na v\u00fdrobu rezn\u00fdch n\u00e1strojov a br\u00fasnych materi\u00e1lov, ako aj na v\u00fdrobu vysokoteplotn\u00fdch dielov odoln\u00fdch proti opotrebeniu, ako s\u00fa lo\u017eisk\u00e1 a tesnenia, v aplik\u00e1ci\u00e1ch stroj\u00e1rskeho priemyslu.<\/p>\n
V\u010faka jedine\u010dnej kombin\u00e1cii stabiln\u00fdch chemick\u00fdch vlastnost\u00ed, vynikaj\u00facej tepelnej vodivosti, n\u00edzkeho koeficientu tepelnej roz\u0165a\u017enosti, tvrdosti a mechanickej pevnosti sa karbid krem\u00edka \u0161iroko vyu\u017e\u00edva v mnoh\u00fdch odvetviach, medzi ktor\u00e9 patria ropn\u00fd priemysel, chemick\u00e9 in\u017einierstvo, mikroelektronika, automobilov\u00fd priemysel, leteck\u00fd priemysel, papierensk\u00fd priemysel, laserov\u00e1 technika a \u0165a\u017eba nerastn\u00fdch surov\u00edn. Okrem toho sa karbid krem\u00edka vyu\u017e\u00edva aj v oblasti ochrany \u017eivotn\u00e9ho prostredia, informa\u010dnej elektroniky a v aplik\u00e1ci\u00e1ch zameran\u00fdch na vyu\u017e\u00edvanie energie.<\/p>\n
Karbid krem\u00edka (SiC) je mo\u017en\u00e9 vyr\u00e1ba\u0165 dvoma sp\u00f4sobmi \u2013 reak\u010dn\u00fdm sp\u00e1jan\u00edm a spekan\u00edm \u2013, pri\u010dom oba postupy ovplyv\u0148uj\u00fa jeho kone\u010dn\u00fa mikrostrukt\u00faru. Reak\u010dne sp\u00e1jan\u00fd SiC sa zvy\u010dajne vyr\u00e1ba infiltr\u00e1ciou lisovan\u00fdch telies pozost\u00e1vaj\u00facich zo zmes\u00ed krem\u00edka a uhl\u00edka tekut\u00fdm krem\u00edkom, ktor\u00fd n\u00e1sledne reaguje s \u010fal\u0161\u00edmi molekulami krem\u00edka a uhl\u00edka a vytv\u00e1ra tak \u010fal\u0161ie v\u00e4zby SiC, zatia\u013e \u010do spekan\u00fd SiC sa vyr\u00e1ba pomocou be\u017en\u00fdch techn\u00edk formovania keramiky a neoxidov\u00fdch spekac\u00edch pr\u00edsad.<\/p>\n
V\u010faka svojej vynikaj\u00facej obrobite\u013enosti je karbid krem\u00edka vynikaj\u00facim materi\u00e1lom na v\u00fdrobu odoln\u00fdch tesniacich komponentov, najm\u00e4 v kombin\u00e1cii s grafitom. T\u00e1to kombin\u00e1cia pon\u00faka ni\u017e\u0161ie koeficienty trenia ako keramika z oxidu hlinit\u00e9ho a tvrd\u00e9 zliatiny a zachov\u00e1 si svoj tvar aj pri vysok\u00fdch hodnot\u00e1ch PV, \u010d\u00edm zabr\u00e1ni \u00faniku chemik\u00e1li\u00ed, ako s\u00fa l\u00fahy a kyseliny, do \u017eivotn\u00e9ho prostredia.<\/p>\n
<\/p>","protected":false},"excerpt":{"rendered":"
Silicon Carbide is one of the hardest and most durable advanced ceramic materials, used both for its hardness as an […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","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":[3],"tags":[],"class_list":["post-23","post","type-post","status-publish","format-standard","hentry","category-sic-knowledge"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/siliconcarbideceramic.net\/sk\/wp-json\/wp\/v2\/posts\/23","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=23"}],"version-history":[{"count":3,"href":"https:\/\/siliconcarbideceramic.net\/sk\/wp-json\/wp\/v2\/posts\/23\/revisions"}],"predecessor-version":[{"id":29,"href":"https:\/\/siliconcarbideceramic.net\/sk\/wp-json\/wp\/v2\/posts\/23\/revisions\/29"}],"wp:attachment":[{"href":"https:\/\/siliconcarbideceramic.net\/sk\/wp-json\/wp\/v2\/media?parent=23"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/siliconcarbideceramic.net\/sk\/wp-json\/wp\/v2\/categories?post=23"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/siliconcarbideceramic.net\/sk\/wp-json\/wp\/v2\/tags?post=23"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}