Karbid krem\u00edka (SiC) je anorganick\u00fd keramick\u00fd materi\u00e1l, ktor\u00fd sa \u0161iroko pou\u017e\u00edva v mechanicky a tepelne n\u00e1ro\u010dn\u00fdch aplik\u00e1ci\u00e1ch a ktor\u00fd je z h\u013eadiska tvrdosti na druhom mieste po karbide b\u00f3ru a diamante.<\/p>\n
Karborundum prv\u00fdkr\u00e1t objavil americk\u00fd vyn\u00e1lezca Edward G. Acheson pri pokuse o v\u00fdrobu umel\u00fdch diamantov v roku 1891 a odvtedy sa stalo nenahradite\u013enou s\u00fa\u010das\u0165ou rezn\u00fdch n\u00e1strojov a \u017eiaruvzdorn\u00fdch oblo\u017een\u00ed.<\/p>\n
Karbid krem\u00edka m\u00e1 p\u00f4sobiv\u00e9 fyzik\u00e1lne vlastnosti, ale \u010dasto sa nespr\u00e1vne ch\u00e1pe a interpretuje. Tvrdos\u0165 sa \u010dasto zamie\u0148a s pevnos\u0165ou; v skuto\u010dnosti sa vz\u0165ahuje sk\u00f4r na odolnos\u0165 materi\u00e1lov vo\u010di deform\u00e1cii ne\u017e na tuhos\u0165 alebo pevnos\u0165.<\/p>\n
Tvrdos\u0165 materi\u00e1lov sa ur\u010duje ich mikrotvrdos\u0165ou alebo modulom pru\u017enosti v malom \u0161myku vo v\u0161etk\u00fdch smeroch, nie ich tuhos\u0165ou alebo Youngov\u00fdm modulom, ktor\u00fd z\u00e1vis\u00ed od r\u00f4znych faktorov vr\u00e1tane geometrie a chemick\u00e9ho zlo\u017eenia; napr\u00edklad karbid krem\u00edka je ove\u013ea tvrd\u0161\u00ed ako diamant, ale menej tuh\u00fd ako napr\u00edklad osmium alebo volfr\u00e1m.<\/p>\n
Tvrd\u0161ie materi\u00e1ly b\u00fdvaj\u00fa odolnej\u0161ie vo\u010di po\u0161kodeniu, ale menej pru\u017en\u00e9 alebo elastick\u00e9 ako ich m\u00e4k\u0161ie n\u00e1protivky - preto sa niekedy tvrdos\u0165 a tvrdos\u0165 pou\u017e\u00edvaj\u00fa zamenite\u013ene.<\/p>\n
Karbid krem\u00edka sa m\u00f4\u017ee pochv\u00e1li\u0165 najvy\u0161\u0161ou tvrdos\u0165ou spomedzi v\u0161etk\u00fdch kry\u0161talick\u00fdch zl\u00fa\u010den\u00edn, hoci nie je tak\u00fd tvrd\u00fd ako diamant. Karbid krem\u00edka sa vyr\u00e1ba priemyselne na pou\u017eitie ako abraz\u00edvum a v in\u00fdch metalurgick\u00fdch a \u017eiaruvzdorn\u00fdch aplik\u00e1ci\u00e1ch, ako aj pri v\u00fdrobe keramiky.<\/p>\n
U kompozitov obsahuj\u00facich karbid krem\u00edka sa zvy\u0161uje tvrdos\u0165 \u00famerne ich hmotnostn\u00e9mu podielu SiC, preto\u017ee s\u00fa zabudovan\u00e9 v matrici a s\u00fa odolnej\u0161ie vo\u010di po\u0161kodeniu a \u0161mykov\u00fdm sil\u00e1m.<\/p>\n
Karbid krem\u00edka m\u00e1 vysok\u00fa tepeln\u00fa vodivos\u0165, \u010do znamen\u00e1, \u017ee \u013eahko pren\u00e1\u0161a teplo. Deje sa to prostredn\u00edctvom molekul\u00e1rnych vibr\u00e1ci\u00ed a kontaktu medzi molekulami v materi\u00e1li; pri tomto prenose zohr\u00e1vaj\u00fa podstatn\u00fa \u00falohu teplotn\u00e9 gradienty v celej jeho hr\u00fabke, ako aj hustota a kry\u0161t\u00e1lov\u00e1 \u0161trukt\u00fara jeho jednotliv\u00fdch \u010dast\u00ed.<\/p>\n
Tepeln\u00e1 vodivos\u0165 je z\u00e1kladnou vlastnos\u0165ou pri v\u00fdrobe modernej keramiky, ktor\u00e1 sa pou\u017e\u00edva napr\u00edklad v automobilov\u00fdch brzd\u00e1ch a spojk\u00e1ch a umo\u017e\u0148uje t\u00fdmto materi\u00e1lom pracova\u0165 pri vy\u0161\u0161\u00edch teplot\u00e1ch bez straty mechanick\u00fdch vlastnost\u00ed. Keramika sa tie\u017e \u0161iroko pou\u017e\u00edva ako materi\u00e1l nepriestreln\u00fdch viest, preto\u017ee jej pevnos\u0165 dok\u00e1\u017ee odola\u0165 extr\u00e9mne ve\u013ekej sile bez toho, aby sa zlomila.<\/p>\n
Vysok\u00e1 vodivos\u0165 SiC umo\u017e\u0148uje polovodi\u010dom vyroben\u00fdm z SiC pracova\u0165 pri ove\u013ea vy\u0161\u0161\u00edch frekvenci\u00e1ch a teplot\u00e1ch ako tranzistory a di\u00f3dy na b\u00e1ze krem\u00edka, \u010do zni\u017euje straty energie a z\u00e1rove\u0148 zvy\u0161uje spo\u013eahlivos\u0165.<\/p>\n
Chemick\u00e9 zlo\u017eenie karbidu krem\u00edka z neho tie\u017e rob\u00ed vysoko stabiln\u00fd materi\u00e1l, ktor\u00fd odol\u00e1va kor\u00f3zii, \u010do z neho rob\u00ed jednu z najodolnej\u0161\u00edch priemyseln\u00fdch a metalurgick\u00fdch keram\u00edk, ktor\u00e9 s\u00fa dnes k dispoz\u00edcii. M\u00f4\u017ee sa pochv\u00e1li\u0165 vynikaj\u00facou odolnos\u0165ou vo\u010di chemik\u00e1li\u00e1m, ako s\u00fa kyseliny chlorovod\u00edkov\u00e1, s\u00edrov\u00e1 a fluorovod\u00edkov\u00e1, ako aj vo\u010di koncentrovan\u00fdm z\u00e1sad\u00e1m, napr\u00edklad hydroxidu sodn\u00e9mu. Okrem toho sa karbid krem\u00edka m\u00f4\u017ee dokonca tavi\u0165 pri vysok\u00fdch teplot\u00e1ch a vytv\u00e1ra\u0165 pevn\u00e9 v\u00e4zby so sklom alebo in\u00fdmi krehk\u00fdmi materi\u00e1lmi, ako je keramika.<\/p>\n
Elektrick\u00e1 vodivos\u0165 SiC z neho rob\u00ed neocenite\u013en\u00fd materi\u00e1l v energetick\u00fdch aplik\u00e1ci\u00e1ch, najm\u00e4 v t\u00fdch, ktor\u00e9 zah\u0155\u0148aj\u00fa ve\u013ek\u00e9 mno\u017estvo pr\u00fadu. V\u010faka svojim p\u00f4sobiv\u00fdm elektrick\u00fdm vlastnostiam sa SiC stal \u017eivotaschopnou alternat\u00edvou krem\u00edkov\u00fdch polovodi\u010dov pre n\u00e1ro\u010dn\u00e9 pou\u017eitie, ako je v\u00fdkonov\u00e1 elektronika elektrick\u00fdch automobilov a pr\u00edstrojov\u00e9 vybavenie sond na Marse alebo Venu\u0161i (Mantooth, Zetterling a Rusu).<\/p>\n
Vysok\u00fa elektrick\u00fa vodivos\u0165 SiC mo\u017eno prip\u00edsa\u0165 jeho \u0161irok\u00e9mu p\u00e1smov\u00e9mu rozhraniu. Medzera medzi valen\u010dn\u00fdm a vodivostn\u00fdm p\u00e1smom ur\u010duje, \u010di je materi\u00e1l vodi\u010d alebo izolant; pri expanz\u00edvnej medzere m\u00f4\u017eu elektr\u00f3ny vo\u013ene prech\u00e1dza\u0165 z valen\u010dn\u00e9ho p\u00e1sma do vodivostn\u00e9ho p\u00e1sma, zatia\u013e \u010do pre izolant je na prekro\u010denie tejto medzery potrebn\u00e9 ne\u00fanosne ve\u013ek\u00e9 mno\u017estvo energie.<\/p>\n
Chemick\u00e1 infiltr\u00e1cia p\u00e1r (CVI) alebo polymerizovan\u00e1 impregn\u00e1cia - pyrol\u00fdza (PIP) n-typu SiC do matrice zvy\u0161uje elektrick\u00fa vodivos\u0165 o dva a\u017e tri r\u00e1dy pri zv\u00fd\u0161en\u00fdch teplot\u00e1ch v d\u00f4sledku tvorby kry\u0161t\u00e1lov s ni\u017e\u0161\u00edmi p\u00e1smov\u00fdmi medzerami ako v pr\u00edpade \u010dist\u00e9ho karbidu krem\u00edka. Toto zv\u00fd\u0161enie mo\u017eno prip\u00edsa\u0165 tvorbe nov\u00fdch kry\u0161t\u00e1lov SiC s v\u00e4\u010d\u0161ou elektrickou vodivos\u0165ou.<\/p>\n
Materi\u00e1l Si-SiC m\u00e1 elektrick\u00fa vodivos\u0165 105 a\u017e 107 Ohm*cm v\u010faka n\u00edzkej tepelnej roz\u0165a\u017enosti a elektrickej vodivosti 105 a\u017e 107 Ohm*cm na cm \u0161tvorcov\u00fd, v\u010faka \u010domu je vhodn\u00fd na aplik\u00e1cie vy\u017eaduj\u00face vysok\u00e9 pr\u00fady, teploty, odolnos\u0165 proti er\u00f3zii a ochranu proti kor\u00f3zii. V\u010faka kombin\u00e1cii t\u00fdchto vlastnost\u00ed vystupuje Si-SiC ako ide\u00e1lny kandid\u00e1t.<\/p>\n
Karbid krem\u00edka sa sklad\u00e1 z at\u00f3mov uhl\u00edka a krem\u00edka usporiadan\u00fdch do \u0161tvorstrann\u00fdch \u0161trukt\u00far spojen\u00fdch pevn\u00fdmi v\u00e4zbami, ktor\u00e9 tvoria jeho kry\u0161t\u00e1lov\u00fa \u0161trukt\u00faru. V\u010faka t\u00fdmto siln\u00fdm v\u00e4zb\u00e1m m\u00e1 karbid krem\u00edka mimoriadne tvrd\u00fd a h\u00fa\u017eevnat\u00fd povrch, ktor\u00fd je odoln\u00fd aj vo\u010di chemik\u00e1li\u00e1m; jeho odolnos\u0165 ho chr\u00e1ni aj pred p\u00f4soben\u00edm kysel\u00edn, ako aj pred tepeln\u00fdm \u0161okom pri teplote a\u017e 1600 \u00b0C. Okrem toho je v\u010faka svojej vynikaj\u00facej odolnosti vo\u010di po\u0161kodeniu n\u00e1razom vhodn\u00fd na aplik\u00e1cie, kde hr\u00e1 \u00falohu fyzick\u00e9 opotrebovanie, ako s\u00fa napr\u00edklad striekacie d\u00fdzy, tryskacie d\u00fdzy alebo s\u00fa\u010dasti cykl\u00f3nov.<\/p>\n
Keramick\u00e9 nano\u010dastice s\u00fa jedn\u00fdm z naj\u013eah\u0161\u00edch, najpevnej\u0161\u00edch a najtvrd\u0161\u00edch keramick\u00fdch materi\u00e1lov. M\u00f4\u017ee sa pochv\u00e1li\u0165 vynikaj\u00facimi elektrick\u00fdmi vlastnos\u0165ami s vynikaj\u00facou tepelnou vodivos\u0165ou a n\u00edzkym koeficientom tepelnej roz\u0165a\u017enosti; okrem toho odol\u00e1va vysok\u00fdm teplot\u00e1m ako polovodi\u010dov\u00fd materi\u00e1l.<\/p>\n
Karbid krem\u00edka sa m\u00f4\u017ee pochv\u00e1li\u0165 \u0161irokou p\u00e1smovou medzerou medzi polovodi\u010dmi, v\u010faka \u010domu je vhodn\u00fd pre v\u00fdkonov\u00fa elektroniku. Jeho nap\u00e4\u0165ov\u00e1 odolnos\u0165 je 10-kr\u00e1t vy\u0161\u0161ia ako u be\u017en\u00e9ho krem\u00edka a v syst\u00e9moch pracuj\u00facich pri vysok\u00fdch r\u00fdchlostiach alebo teplot\u00e1ch vynik\u00e1 nad nitridom g\u00e1lia.<\/p>\n
Syntetick\u00fd diamant sa vyr\u00e1ba predov\u0161etk\u00fdm na pou\u017eitie ako abraz\u00edvum, av\u0161ak medzi \u010fal\u0161ie aplik\u00e1cie syntetick\u00e9ho diamantu m\u00f4\u017eu patri\u0165 lapid\u00e1rne aplik\u00e1cie. Vzh\u013eadom na jeho dlh\u00fa \u017eivotnos\u0165 a odolnos\u0165 vo\u010di abr\u00e1zii je syntetick\u00fd diamant \u010dasto vyu\u017e\u00edvan\u00fd modern\u00fdmi lapid\u00e1rmi ako pr\u00edsada v\u010faka jeho trvanlivosti a odolnosti vo\u010di po\u0161kodeniu sp\u00f4soben\u00e9mu opotrebovan\u00edm a oderu. Okrem toho mo\u017eno syntetick\u00fd diamant n\u00e1js\u0165 aj ako abraz\u00edvum v br\u00fasnych n\u00e1strojoch, automobilov\u00fdch s\u00fa\u010diastkach a \u017eiaruvzdorn\u00fdch materi\u00e1loch - rovnako ako je tvrd\u00fd, odoln\u00fd a u\u017eito\u010dn\u00fd v kombin\u00e1cii s materi\u00e1lmi, ako je oce\u013e a karbid volfr\u00e1mu, pri obr\u00e1bac\u00edch aplik\u00e1ci\u00e1ch v kombin\u00e1cii s in\u00fdmi tvrd\u00fdmi a odoln\u00fdmi materi\u00e1lmi, ako je oce\u013e a karbid volfr\u00e1mu, na dosiahnutie lep\u0161\u00edch v\u00fdsledkov.<\/p>","protected":false},"excerpt":{"rendered":"
Silicon carbide (SiC) is an inorganic ceramic material widely used in mechanically and thermally demanding applications, second only to boron carbide and diamond in terms of hardness. Carborundum was first discovered by American inventor Edward G. Acheson while trying to produce artificial diamonds in 1891 and has become an indispensable component in cutting tools and […]<\/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-308","post","type-post","status-publish","format-standard","hentry","category-knowledge"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/posts\/308","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=308"}],"version-history":[{"count":1,"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/posts\/308\/revisions"}],"predecessor-version":[{"id":309,"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/posts\/308\/revisions\/309"}],"wp:attachment":[{"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/media?parent=308"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/categories?post=308"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/tags?post=308"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}