Karbid krem\u00edka je mimoriadne tvrd\u00fd, ale st\u00e1le menej tvrd\u00fd ako diamant. St\u00e1le v\u0161ak patr\u00ed na druh\u00e9 miesto medzi extr\u00e9mne tvrd\u00fdmi materi\u00e1lmi.<\/p>\n
P\u00f3rovit\u00e9 diamantov\u00e9 preformy s uhl\u00edkovou v\u00e4zbou sa infiltruj\u00fa infiltr\u00e1ciou krem\u00edka kapil\u00e1rnou silou pri teplot\u00e1ch presahuj\u00facich jeho teplotu topenia, pri\u010dom sa uhl\u00edkov\u00e9 spojivo men\u00ed na grafit.<\/p>\n
Diamant z karbidu krem\u00edka je extr\u00e9mne vysokoteplotn\u00fd materi\u00e1l s vynikaj\u00facou tepelnou vodivos\u0165ou, ktor\u00fd sa \u0161iroko pou\u017e\u00edva v elektrotechnike, elektronike a priemysle. Medzi jeho aplik\u00e1cie patr\u00ed chladenie a ohrev polovodi\u010dov, tranzistorov a v\u00fdkonov\u00fdch LED di\u00f3d, ako aj aplik\u00e1ci\u00ed na osvetlenie LED displejov. Tepeln\u00e1 vodivos\u0165 kompozitov SiC\/diamant z\u00e1vis\u00ed od viacer\u00fdch faktorov vr\u00e1tane mno\u017estva a ve\u013ekosti diamantu, zlo\u017eenia ich spojovacieho materi\u00e1lu a \u0161trukt\u00fary ich rozhran\u00ed medzi komponentmi, ako aj vplyvu grafitovej medzivrstvy na tepeln\u00fa vodivos\u0165 tohto materi\u00e1lu.<\/p>\n
Vytvorenie vysoko odoln\u00fdch materi\u00e1lov proti opotrebovaniu s vynikaj\u00facou tepelnou vodivos\u0165ou je od minul\u00e9ho desa\u0165ro\u010dia trval\u00fdm cie\u013eom v\u00fdskumu a v\u00fdvoja. \"Diamantov\u00e9 materi\u00e1ly z karbidu krem\u00edka\" mo\u017eno vyrobi\u0165 infiltr\u00e1ciou tekut\u00e9ho krem\u00edka prostredn\u00edctvom kapil\u00e1rnych s\u00edl pri teplot\u00e1ch vy\u0161\u0161\u00edch ako 1425 stup\u0148ov Celzia, \u010d\u00edm sa vytvoria kubick\u00e9 \u0161trukt\u00fary b-SiC, ktor\u00e9 by mohli nahradi\u0165 tradi\u010dn\u00e9 oce\u013eov\u00e9 materi\u00e1ly ako lo\u017eisk\u00e1, tesnenia alebo vlo\u017eky v priemyseln\u00fdch aplik\u00e1ci\u00e1ch.<\/p>\n
Na dosiahnutie optim\u00e1lnej tepelnej vodivosti v kompozitoch SiC\/diamant mo\u017eno na zv\u00fd\u0161enie tepelnej vodivosti pou\u017ei\u0165 bimod\u00e1lne rozlo\u017eenie diamantov\u00fdch z\u0155n r\u00f4znych ve\u013ekost\u00ed a frakci\u00ed. Bimod\u00e1lne syst\u00e9my pon\u00fakaj\u00fa v\u00fdrazne vy\u0161\u0161iu tepeln\u00fa vodivos\u0165 v porovnan\u00ed s monomod\u00e1lnymi syst\u00e9mami v\u010faka tomu, \u017ee medzi diamantov\u00fdmi zrnami a ich hostite\u013eskou matricou z matricov\u00e9ho materi\u00e1lu b-SiC s\u00fa grafitick\u00e9 at\u00f3mov\u00e9 vrstvy.<\/p>\n
Okrem toho s\u00fa grafitov\u00e9 at\u00f3mov\u00e9 vrstvy usporiadan\u00e9 kolmo na rozhranie, \u010d\u00edm sa vytv\u00e1raj\u00fa bimod\u00e1lne syst\u00e9my s relat\u00edvne ve\u013ek\u00fdm povrchom, ktor\u00fd zvy\u0161uje tepeln\u00fa vodivos\u0165. Tepeln\u00e1 vodivos\u0165 sa e\u0161te zvy\u0161uje, ak sa diamant spek\u00e1 pri vy\u0161\u0161\u00edch teplot\u00e1ch alebo sa po\u010das infiltr\u00e1cie krem\u00edka udr\u017eiava krat\u0161\u00ed \u010das - \u010d\u00edm sa zvy\u0161uje nad r\u00e1mec tepelnej vodivosti \u010dist\u00e9ho b-SiC! Okrem toho tepeln\u00e1 vodivos\u0165 materi\u00e1lov z\u00e1vis\u00ed aj od mno\u017estva vo\u013en\u00e9ho krem\u00edka a diamantu.<\/p>\n
Karbid krem\u00edka, ktor\u00fd sa sklad\u00e1 z at\u00f3mov krem\u00edka a uhl\u00edka, m\u00e1 vynikaj\u00facu tvrdos\u0165 9,5 pod\u013ea Mohsa, \u010d\u00edm sa rad\u00ed na druh\u00e9 miesto po diamante, pokia\u013e ide o tvrdos\u0165. V\u010faka svojej pevnosti a trvanlivosti nach\u00e1dza karbid krem\u00edka po\u010detn\u00e9 priemyseln\u00e9 vyu\u017eitie.<\/p>\n
Karbid krem\u00edka m\u00e1 mnoho spolo\u010dn\u00fdch vlastnost\u00ed s diamantom, vr\u00e1tane jeho kry\u0161t\u00e1lovej \u0161trukt\u00fary, ktor\u00e1 je tetraedrick\u00e1 - \u0161tyri at\u00f3my ka\u017ed\u00e9ho prvku zdie\u013eaj\u00fa jednu kubick\u00fa mrie\u017eku s centrovan\u00fdm povrchom a vytv\u00e1raj\u00fa siln\u00e9 kovalentn\u00e9 v\u00e4zby podobn\u00e9 siln\u00fdm tetraedrick\u00fdm v\u00e4zb\u00e1m diamantu - ako aj vysok\u00fa pevnos\u0165 v \u0165ahu a n\u00edzky koeficient trenia, \u010do z oboch materi\u00e1lov rob\u00ed skvel\u00e9 materi\u00e1ly na obrobky.<\/p>\n
Karbid krem\u00edka sa m\u00f4\u017ee vyr\u00e1ba\u0165 viacer\u00fdmi technikami, pri\u010dom syntetick\u00fd karbid krem\u00edka sa vyr\u00e1ba taven\u00edm kremenn\u00e9ho piesku, ropn\u00e9ho koksu (alebo uho\u013en\u00e9ho koksu), drevnej \u0161tiepky alebo in\u00fdch surov\u00edn vo vysokoteplotn\u00fdch peciach. Po vytvoren\u00ed karbid krem\u00edka vykazuje tvrdos\u0165, m\u00e1 zv\u00fd\u0161en\u00fa teplotu topenia a odol\u00e1va oxid\u00e1cii aj pri extr\u00e9mnych teplotn\u00fdch podmienkach.<\/p>\n
Karbid krem\u00edka m\u00e1 mnoho praktick\u00fdch vyu\u017eit\u00ed v priemysle. Jedn\u00fdm z nich je pou\u017eitie v br\u00fasnych materi\u00e1loch. V\u010faka svojej v\u00fdnimo\u010dnej odolnosti a pevnosti je karbid krem\u00edka nenahradite\u013enou s\u00fa\u010das\u0165ou br\u00fasnych papierov, br\u00fasnych kot\u00fa\u010dov a rezn\u00fdch n\u00e1strojov. Karbid krem\u00edka sa pou\u017e\u00edva aj ako izola\u010dn\u00e1 zlo\u017eka v priemyseln\u00fdch peciach, ako aj ako s\u00fa\u010diastky odoln\u00e9 vo\u010di opotrebovaniu na \u010derpadl\u00e1ch a raketov\u00fdch motoroch a ako polovodi\u010dov\u00e9 substr\u00e1ty pou\u017e\u00edvan\u00e9 na v\u00fdrobu sveteln\u00fdch di\u00f3d (LED).<\/p>\n
Existuj\u00fa r\u00f4zne met\u00f3dy v\u00fdroby karbidu krem\u00edka. Tradi\u010dn\u00e9 techniky zah\u0155\u0148aj\u00fa pou\u017eitie procesu spekania, pri ktorom sa pr\u00e1\u0161kov\u00fd krem\u00edk a uhl\u00edk kombinuj\u00fa vo vysokotlakovej tavenine, aby sa vytvoril spekan\u00fd blok karbidu krem\u00edka, ktor\u00fd sa potom m\u00f4\u017ee reza\u0165 na po\u017eadovan\u00e9 tvary a ve\u013ekosti. In\u00e1 alternat\u00edva zah\u0155\u0148a reakciu tekut\u00e9ho krem\u00edka s p\u00f3rovit\u00fdm grafitom, \u010d\u00edm sa vytvor\u00ed \u010dierny syntetick\u00fd moissanit, ktor\u00fd m\u00e1 niektor\u00e9 rovnak\u00e9 mechanick\u00e9 vlastnosti bez toho, aby bol tak\u00fd n\u00e1kladn\u00fd.<\/p>\n
Zistilo sa, \u017ee \u0161peci\u00e1lne vyroben\u00e9 diamantov\u00e9 materi\u00e1ly s v\u00e4zbou karbidu krem\u00edka s grafitov\u00fdmi medzivrstvami na rozhran\u00ed sa vyzna\u010duj\u00fa v\u00fdnimo\u010dne vysokou pevnos\u0165ou, ktor\u00e1 prevy\u0161uje dokonca aj pevnos\u0165 bezgrafitov\u00fdch rozhran\u00ed diamant\/SiC, hoci nie je jasn\u00e9, \u010di je to sp\u00f4soben\u00e9 medzivrstvami grafitu.<\/p>\n
Diamanty z karbidu krem\u00edka s\u00fa extr\u00e9mne odoln\u00e9 materi\u00e1ly s vynikaj\u00facou chemickou stabilitou, v\u010faka \u010domu s\u00fa vhodn\u00e9 na pou\u017eitie pri opotrebovan\u00ed, ako s\u00fa tesnenia, vlo\u017eky a d\u00fdzy. Okrem toho s\u00fa tieto diamanty skvel\u00fdmi rezn\u00fdmi n\u00e1strojmi. V\u010faka ich silnej kry\u0161t\u00e1lovej \u0161trukt\u00fare a dobr\u00fdm vlastnostiam tvrdosti je obr\u00e1banie diamantov karbidu krem\u00edka v porovnan\u00ed s mnoh\u00fdmi in\u00fdmi tvrd\u00fdmi materi\u00e1lmi pomerne jednoduch\u00e9 a maj\u00fa aj n\u00edzky koeficient trenia, v\u010faka \u010domu s\u00fa vhodn\u00e9 na priemyseln\u00e9 pou\u017eitie.<\/p>\n
Diamanty z karbidu krem\u00edka zaznamenali r\u00fdchly v\u00fdvoj v d\u00f4sledku zv\u00fd\u0161en\u00fdch po\u017eiadaviek na odolnos\u0165 proti opotrebovaniu. Karbid krem\u00edka, anorganick\u00e1 zl\u00fa\u010denina pozost\u00e1vaj\u00faca z uhl\u00edka a krem\u00edka s hexagon\u00e1lnou kry\u0161t\u00e1lovou \u0161trukt\u00farou, sa m\u00f4\u017ee vyr\u00e1ba\u0165 v r\u00f4znych tvaroch a ve\u013ekostiach. Edward Goodrich Acheson vytvoril prv\u00fa zl\u00fa\u010deninu karbidu krem\u00edka v roku 1891 zahrievan\u00edm \u00edlu a pr\u00e1\u0161kov\u00e9ho koksu v \u017eeleznej miske, a\u017e k\u00fdm sa nevytvorili modr\u00e9 kry\u0161t\u00e1ly, ktor\u00e9 boli zn\u00e1me ako karborundum - Acheson veril, \u017ee tento materi\u00e1l bude ma\u0165 vy\u0161\u0161iu hodnotu ako uhlie, preto\u017ee sa d\u00e1 pou\u017ei\u0165 na v\u00fdrobu kovov.<\/p>\n
Karbid krem\u00edka sa od \u010dist\u00e9ho diamantu v\u00fdrazne l\u00ed\u0161i t\u00fdm, \u017ee m\u00e1 v\u00e4\u010d\u0161iu stabilitu pri vysok\u00fdch teplot\u00e1ch a n\u00edzky koeficient trenia, pri\u010dom je v\u00fdrazne lacnej\u0161\u00ed. Preto sa karbid krem\u00edka stal ob\u013e\u00faben\u00fdm materi\u00e1lom na priemyseln\u00e9 pou\u017eitie.<\/p>\n
Ke\u010f sa pou\u017e\u00edva ako podkladov\u00fd pr\u00e1\u0161ok pre diamantovo-siC predlisky, podkladov\u00fd pr\u00e1\u0161ok a-Si3N4 zabra\u0148uje tvorbe karbidu krem\u00edka a tvorbe korpor\u00e1tnych vrstiev - \u010d\u00edm v\u00fdrazne zvy\u0161uje pevnos\u0165 diamantovo-siC rozhrania v porovnan\u00ed s be\u017en\u00fdmi vzorkami vlo\u017een\u00fdmi do roztaven\u00e9ho krem\u00edka.<\/p>\n
Presn\u00e1 povaha t\u00fdchto rozhran\u00ed v\u0161ak zost\u00e1va z ve\u013ekej \u010dasti neobjasnen\u00e1. Mohlo by \u00eds\u0165 o d\u00f4sledok slab\u0161\u00edch v\u00e4zieb medzi grafitov\u00fdmi rovinami alebo r\u00f4znych f\u00e1z na rozhran\u00ed, ktor\u00e9 si vy\u017eaduj\u00fa \u010fal\u0161\u00ed v\u00fdskum, aby sa plne pochopili.<\/p>\n
Na pos\u00fadenie rozlo\u017eenia at\u00f3movej hustoty v amorfnej vrstve z materi\u00e1lu 3 C-SiC\/diamant bola pou\u017eit\u00e1 energetick\u00e1 disperzn\u00e1 r\u00f6ntgenov\u00e1 spektrometria (EDX). V profiloch intenzity at\u00f3mov uhl\u00edka a krem\u00edka v bl\u00edzkosti ich as-bonded rozhrania sa pozoroval postupn\u00fd pokles, pri\u010dom uhl\u00edk vykazoval menej strm\u00fd sklon. Krem\u00edk vykazoval mierne konk\u00e1vne profily hustoty, zatia\u013e \u010do profily uhl\u00edka boli pozvo\u013enej\u0161ie.<\/p>\n
Diamanty s\u00fa pr\u00edrodn\u00e9 drahokamy, ktor\u00e9 vznikali mili\u00f3ny rokov, ale ich v\u00fdroba sa d\u00e1 uskuto\u010dni\u0165 synteticky v laborat\u00f3riu za ove\u013ea menej pe\u0148az\u00ed. Karbid krem\u00edka, \u010fal\u0161\u00ed syntetick\u00fd drahokam s podobn\u00fdmi vlastnos\u0165ami, ale ove\u013ea ni\u017e\u0161\u00edmi n\u00e1kladmi, je ove\u013ea odolnej\u0161\u00ed a cenovo v\u00fdhodnej\u0161\u00ed. Jeho vysok\u00fd index lomu mu umo\u017e\u0148uje odr\u00e1\u017ea\u0165 svetlo \u00fa\u010dinnej\u0161ie ako in\u00e9 drahokamy, pri\u010dom v\u010faka svojej odolnosti je vhodn\u00fd na ka\u017edodenn\u00e9 nosenie. Okrem toho jeho n\u00edzky bod topenia znamen\u00e1, \u017ee odol\u00e1va vysok\u00fdm teplot\u00e1m aj chemik\u00e1li\u00e1m bez toho, aby pod tlakom praskol.<\/p>\n
Mikro\u0161trukt\u00fara kompozitov diamant-karbid krem\u00edka sa zvy\u010dajne sklad\u00e1 z navz\u00e1jom sa prel\u00ednaj\u00facich trojrozmern\u00fdch siet\u00ed zlo\u017een\u00fdch z SiC a diamantu. Ve\u013ekos\u0165 \u010dast\u00edc a morfol\u00f3gia ur\u010duje kone\u010dn\u00fa \u0161trukt\u00faru trojit\u00e9ho spoja karbidov krem\u00edka; typicky sa grafitov\u00e9 vrstvy at\u00f3mov rozhrania orientuj\u00fa kolmo k povrchu diamantu\/SiC a vytv\u00e1raj\u00fa s n\u00edm pevn\u00e9 v\u00e4zby - ich hr\u00fabka je zvy\u010dajne ove\u013ea men\u0161ia ako d\u013a\u017eka v\u00e4zby medzi at\u00f3mami karbidu krem\u00edka a vrstvami at\u00f3mov diamantu.<\/p>\n
Pre optim\u00e1lnu tepeln\u00fa vodivos\u0165 diamantu karbidu krem\u00edka je ve\u013emi d\u00f4le\u017eit\u00e9 pochopi\u0165, ako jeho at\u00f3my vz\u00e1jomne p\u00f4sobia. Synchrotr\u00f3nov\u00fd r\u00f6ntgenov\u00fd l\u00fa\u010d mo\u017eno pou\u017ei\u0165 na sk\u00famanie rozhran\u00ed diamant-karbid krem\u00edka, ich \u0161trukt\u00farnych parametrov a ich interakcie. V\u00fdsledky uk\u00e1zali slab\u00e9 interakcie medzi \u010dasticami; kontaktn\u00e9 oblasti medzi \u010dasticami diamantu a SiC obsahuj\u00fa sklovit\u00e9 uhl\u00edkov\u00e9 vrstvy, grafitick\u00e9 hrani\u010dn\u00e9 vrstvy a mikrop\u00f3ry - \u010do je zn\u00e1mkou slabej tepelnej vodivosti diamantu.<\/p>\n
SiC a diamant sa navz\u00e1jom \u00fazko ovplyv\u0148uj\u00fa, ale jeho pevnos\u0165 z\u00e1vis\u00ed aj od jeho mikro\u0161trukt\u00fary. T\u00e1to mikro\u0161trukt\u00fara pozost\u00e1va z trojrozmernej siete \u010dast\u00edc diamantu a karbidu krem\u00edka s minim\u00e1lnym pokryt\u00edm grafitov\u00fdmi medzivrstvami na celej ploche povrchu; okrem toho t\u00e1to mikro\u0161trukt\u00fara ur\u010duje aj mechanick\u00e9 vlastnosti, ako je odolnos\u0165 proti lomu.<\/p>\n
Pevnos\u0165 vzorky konzoly sa zvy\u0161uje s v\u00e4\u010d\u0161\u00edm sklonom diamantov\u00e9ho\/SiC rozhrania smerom k jej za\u0165a\u017een\u00e9mu koncu, ako ukazuj\u00fa simul\u00e1cie molekulovej dynamiky paraleln\u00fdch rozhran\u00ed. Vzorka s n\u00e1klonom 40 nanometrov sa uk\u00e1zala ako obzvl\u00e1\u0161\u0165 pevn\u00e1.<\/p>","protected":false},"excerpt":{"rendered":"
Silicon carbide is extremely hard, yet still less so than diamond. But it still ranks second as an extremely hard material. Porous carbon-bonded diamond preforms undergo infiltration by infusing silicon through capillary force at temperatures exceeding its melting point, whereupon the carbon binder transforms into graphite. Thermal Conductivity Silicon carbide diamond is an extremely high-temperature […]<\/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-409","post","type-post","status-publish","format-standard","hentry","category-knowledge"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/posts\/409","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=409"}],"version-history":[{"count":1,"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/posts\/409\/revisions"}],"predecessor-version":[{"id":410,"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/posts\/409\/revisions\/410"}],"wp:attachment":[{"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/media?parent=409"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/categories?post=409"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/tags?post=409"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}