{"id":23,"date":"2024-02-24T16:39:00","date_gmt":"2024-02-24T08:39:00","guid":{"rendered":"http:\/\/siliconcarbideceramic.net\/?p=23"},"modified":"2024-02-29T12:31:52","modified_gmt":"2024-02-29T04:31:52","slug":"prehled-keramickych-materialu-z-karbidu-kremiku","status":"publish","type":"post","link":"https:\/\/siliconcarbideceramic.net\/cs\/an-overview-of-silicon-carbide-ceramic-materials\/","title":{"rendered":"P\u0159ehled keramick\u00fdch materi\u00e1l\u016f z karbidu k\u0159em\u00edku"},"content":{"rendered":"

Karbid k\u0159em\u00edku je jedn\u00edm z nejtvrd\u0161\u00edch a nejodoln\u011bj\u0161\u00edch pokro\u010dil\u00fdch keramick\u00fdch materi\u00e1l\u016f, kter\u00fd se pou\u017e\u00edv\u00e1 jak pro svou tvrdost jako brusn\u00fd materi\u00e1l, tak pro tepelnou odolnost a n\u00edzk\u00fd koeficient tepeln\u00e9 rozta\u017enosti v \u017e\u00e1ruvzdorn\u00fdch a keramick\u00fdch aplikac\u00edch.<\/p>\n

Moissanit se m\u016f\u017ee vyskytovat i v p\u0159\u00edrod\u011b jako pr\u016fhledn\u00fd miner\u00e1l moissanit. Prvn\u00ed um\u011ble syntetizovan\u00e9 vzorky byly vytvo\u0159eny v roce 1891 p\u0159i pokusu Edwarda Achesona o vytvo\u0159en\u00ed um\u011bl\u00fdch diamant\u016f; pozd\u011bji chemik Henri Moissan, nositel Nobelovy ceny, um\u011ble syntetizoval dal\u0161\u00ed vzorky.<\/p>\n

Pevnost p\u0159i vysok\u00fdch teplot\u00e1ch<\/h2>\n

Karbid k\u0159em\u00edku (SiC) je extr\u00e9mn\u011b pevn\u00e1 neoxidov\u00e1 keramika, kter\u00e1 nab\u00edz\u00ed v\u00fdjime\u010dnou odolnost proti korozi a chemick\u00e9mu napaden\u00ed p\u0159i zv\u00fd\u0161en\u00fdch teplot\u00e1ch. SiC nach\u00e1z\u00ed uplatn\u011bn\u00ed jako \u017e\u00e1ruvzdorn\u00fd vyzd\u00edvkov\u00fd materi\u00e1l v pr\u016fmyslov\u00fdch pec\u00edch jako \u017e\u00e1ruvzdorn\u00fd vyzd\u00edvkov\u00fd materi\u00e1l; brusn\u00e9 kotou\u010de; \u0159ezn\u00e9 n\u00e1stroje; a v aplikac\u00edch, kde je d\u016fle\u017eit\u00e1 pevnost, jako jsou brusn\u00e9 kotou\u010de, \u0159ezn\u00e9 n\u00e1stroje a obr\u00e1b\u011bc\u00ed aplikace. Krom\u011b toho tvo\u0159\u00ed SiC komponenty kl\u00ed\u010dov\u00e9 sou\u010d\u00e1sti odporov\u00fdch topn\u00fdch t\u011bles, termistor\u016f pro elektrick\u00e9 pece a tak\u00e9 vyzd\u00edvek trubek a t\u011bsnic\u00edch ploch obsahuj\u00edc\u00edch SiC.<\/p>\n

SiC je zn\u00e1m\u00fd svou vynikaj\u00edc\u00ed tepelnou odolnost\u00ed a pevnost\u00ed p\u0159i zv\u00fd\u0161en\u00fdch teplot\u00e1ch, d\u00edky \u010demu\u017e je vysoce cen\u011bn v pr\u016fmyslov\u00fdch aplikac\u00edch. SiC odol\u00e1v\u00e1 oxidaci p\u0159i teplot\u00e1ch do 1 000 \u00b0C t\u00edm, \u017ee vytv\u00e1\u0159\u00ed ochrannou vrstvu oxidu, kter\u00e1 p\u016fsob\u00ed jako bari\u00e9ra mezi jeho povrchem a prvky, kter\u00e9 obklopuje; p\u0159i vy\u0161\u0161\u00edch teplot\u00e1ch v\u0161ak mohou touto bari\u00e9rou pronikat trhliny a rozptylovat energii prost\u0159ednictv\u00edm mezikrystalick\u00fdch nebo zrnit\u00fdch oblast\u00ed, co\u017e vede k obt\u00ed\u017e\u00edm p\u0159i zvy\u0161ov\u00e1n\u00ed pevnosti p\u0159i zv\u00fd\u0161en\u00fdch teplot\u00e1ch.<\/p>\n

Karbid k\u0159em\u00edku lze vyr\u00e1b\u011bt dv\u011bma r\u016fzn\u00fdmi procesy: reak\u010dn\u00edm spojov\u00e1n\u00edm a slinov\u00e1n\u00edm. Ob\u011b formy maj\u00ed v\u00fdznamn\u00fd vliv na jeho mikrostrukturu, a t\u00edm i na jeho vlastnosti p\u0159i zv\u00fd\u0161en\u00fdch teplot\u00e1ch. Reak\u010dn\u00ed lepen\u00ed zahrnuje infiltraci zelen\u00fdch kompakt\u016f tvo\u0159en\u00fdch sm\u011bs\u00ed SiC a uhl\u00edku kapaln\u00fdm k\u0159em\u00edkem; t\u00edm vznikaj\u00ed struktury s minim\u00e1ln\u00ed zm\u011bnou rozm\u011br\u016f b\u011bhem zpracov\u00e1n\u00ed a s expanzivn\u00edm povrchem. \u017d\u00e1ruvzdorn\u00e1 mikrostruktura j\u00e1dro-pl\u00e1\u0161\u0165 poskytuje jedine\u010dn\u00e9 vlastnosti, kter\u00e9 prokazateln\u011b zvy\u0161uj\u00ed pevnost SiC p\u0159i zv\u00fd\u0161en\u00fdch teplot\u00e1ch.<\/p>\n

Odolnost proti vysok\u00fdm teplot\u00e1m<\/h2>\n

Karbid k\u0159em\u00edku je d\u00edky sv\u00e9 mimo\u0159\u00e1dn\u00e9 pevnosti vynikaj\u00edc\u00edm materi\u00e1lem pro vysokoteplotn\u00ed aplikace, jako jsou keramick\u00e9 brzdov\u00e9 desti\u010dky pro spot\u0159ebn\u00ed automobily. Tento materi\u00e1l je schopen odol\u00e1vat teplot\u00e1m a\u017e 1400 stup\u0148\u016f Celsia a p\u0159itom si zachov\u00e1v\u00e1 v\u00fdjime\u010dnou pevnost a tvrdost, co\u017e z karbidu k\u0159em\u00edku \u010din\u00ed ide\u00e1ln\u00ed materi\u00e1l.<\/p>\n

Karbid k\u0159em\u00edku se od ostatn\u00edch keramick\u00fdch materi\u00e1l\u016f li\u0161\u00ed t\u00edm, \u017ee p\u0159i vysok\u00fdch teplot\u00e1ch nedegraduje ani se netav\u00ed, tak\u017ee je vhodn\u00fd pro pou\u017eit\u00ed v aplikac\u00edch s vysok\u00fdm nam\u00e1h\u00e1n\u00edm a zat\u00ed\u017een\u00edm, jako jsou lo\u017eiska a nepr\u016fst\u0159eln\u00e9 desky, ani\u017e by do\u0161lo k trval\u00e9mu po\u0161kozen\u00ed konstrukce. D\u00edky tomu je karbid k\u0159em\u00edku ide\u00e1ln\u00ed zejm\u00e9na pro aplikace s vysokou m\u00edrou zat\u00ed\u017een\u00ed, jako jsou lo\u017eiska a nepr\u016fst\u0159eln\u00e9 desky.<\/p>\n

Karbid k\u0159em\u00edku se v p\u0159\u00edrod\u011b vyskytuje jako extr\u00e9mn\u011b vz\u00e1cn\u00fd miner\u00e1l moissanit, zat\u00edmco v\u00fdroba syntetick\u00e9ho sic spl\u0148uje po\u017eadavky modern\u00ed n\u00e1rodn\u00ed obrany, jadern\u00e9 energetiky, kosmick\u00fdch technologi\u00ed a leteck\u00e9ho pr\u016fmyslu, kter\u00e9 vy\u017eaduj\u00ed p\u0159esn\u00e9 rozm\u011bry.<\/p>\n

Slinut\u00fd karbid k\u0159em\u00edku se m\u016f\u017ee pochlubit jednou z nejvy\u0161\u0161\u00edch tepeln\u00fdch vodivost\u00ed mezi technickou keramikou, druhou nejvy\u0161\u0161\u00ed po nitridu hlin\u00edku. To lze p\u0159i\u010d\u00edst jeho m\u0159\u00ed\u017ekov\u00e9 kysl\u00edkov\u00e9 struktu\u0159e, kter\u00e1 zp\u016fsobuje velk\u00fd rozptyl fonon\u016f. Jeho tepelnou vodivost lze sice d\u00e1le zv\u00fd\u0161it pou\u017eit\u00edm oxidov\u00fdch p\u0159\u00edsad p\u0159i sp\u00e9k\u00e1n\u00ed, ty by v\u0161ak m\u011bly b\u00fdt omezeny na naprost\u00e9 minimum, aby byla zachov\u00e1na strukturn\u00ed stabilita a oxida\u010dn\u00ed odolnost materi\u00e1lu.<\/p>\n

N\u00edzk\u00fd koeficient tepeln\u00e9 rozta\u017enosti<\/h2>\n

N\u00edzk\u00fd koeficient tepeln\u00e9 rozta\u017enosti karbidu k\u0159em\u00edku z n\u011bj \u010din\u00ed ide\u00e1ln\u00ed materi\u00e1l pro pou\u017eit\u00ed jako kompozit s keramickou matric\u00ed (CMC) v n\u00e1ro\u010dn\u00fdch podm\u00ednk\u00e1ch, d\u00edky \u010demu\u017e se s oblibou pou\u017e\u00edv\u00e1 v aplikac\u00edch, jako jsou plynov\u00e9 turb\u00edny a raketov\u00e9 trysky, kde materi\u00e1ly mus\u00ed odol\u00e1vat vysok\u00fdm teplot\u00e1m i tepeln\u00fdm \u0161ok\u016fm.<\/p>\n

Odolnost v\u016f\u010di korozi \u010din\u00ed z nerezov\u00e9 oceli vynikaj\u00edc\u00ed materi\u00e1l pro vyzd\u00edvky chemick\u00fdch pr\u016fmyslov\u00fdch pec\u00ed, kde odol\u00e1v\u00e1 extr\u00e9mn\u00edm teplot\u00e1m a z\u00e1rove\u0148 si zachov\u00e1v\u00e1 svou struktur\u00e1ln\u00ed integritu. Krom\u011b toho nerezov\u00e1 ocel nab\u00edz\u00ed velkou chemickou stabilitu, kter\u00e1 umo\u017e\u0148uje dlouhodob\u00fd provoz v nep\u0159\u00edzniv\u00fdch kapaln\u00fdch prost\u0159ed\u00edch, jako jsou kysel\u00e9 a z\u00e1sadit\u00e9 roztoky.<\/p>\n

Nejroz\u0161\u00ed\u0159en\u011bj\u0161\u00ed polymorf karbidu k\u0159em\u00edku, forma alfa, se vyskytuje p\u0159i teplot\u00e1ch nad 1700 stup\u0148\u016f Celsia s wurtzitovou krystalovou strukturou a teplotou t\u00e1n\u00ed nad 1700 stup\u0148\u016f Celsia. M\u016f\u017ee v\u0161ak existovat i vz\u00e1cn\u011bj\u0161\u00ed beta forma s krystalovou strukturou zinkov\u00e9ho blendu podobnou diamantu a ni\u017e\u0161\u00ed teplotou t\u00e1n\u00ed 1030 degC - tato vz\u00e1cn\u011bj\u0161\u00ed forma m\u016f\u017ee slou\u017eit jako podpora heterogenn\u00edch katalyz\u00e1tor\u016f.<\/p>\n

Karbid k\u0159em\u00edku se vyskytuje v podob\u011b por\u00e9zn\u00ed i hust\u00e9 keramiky. V\u00fdrobn\u00ed techniky se zna\u010dn\u011b li\u0161\u00ed a kone\u010dn\u00e1 mikrostruktura z\u00e1vis\u00ed na pou\u017eit\u00e9 v\u00fdrobn\u00ed metod\u011b. Reak\u010dn\u011b v\u00e1zan\u00fd SiC se vyr\u00e1b\u00ed infiltrac\u00ed kompakt\u016f sm\u011bsi uhl\u00edku a SiC roztaven\u00fdm k\u0159em\u00edkem, kter\u00fd vz\u00e1jemn\u011b reaguje za vzniku dal\u0161\u00edho SiC, \u010d\u00edm\u017e se p\u016fvodn\u00ed kompakt spoj\u00ed; slinut\u00fd SiC, jako je Hexoloy, se vytv\u00e1\u0159\u00ed b\u011b\u017en\u00fdmi keramick\u00fdmi tv\u00e1\u0159ec\u00edmi procesy p\u0159ed slinut\u00edm za vysok\u00fdch teplot v inertn\u00ed atmosf\u00e9\u0159e.<\/p>\n

Vysok\u00e1 tvrdost<\/h2>\n

Tvrdost karbidu k\u0159em\u00edku na Mohsov\u011b stupnici dosahuje a\u017e 9,5, \u010d\u00edm\u017e se \u0159ad\u00ed na t\u0159et\u00ed m\u00edsto hned za diamant a nitrid boru. D\u00edky tomu je vhodn\u00fd pro \u0159ezn\u00e9 n\u00e1stroje a abrazivn\u00ed materi\u00e1ly a tak\u00e9 pro v\u00fdrobu d\u00edl\u016f odoln\u00fdch proti opot\u0159eben\u00ed p\u0159i vysok\u00fdch teplot\u00e1ch, jako jsou lo\u017eiska a t\u011bsn\u011bn\u00ed ve stroj\u00edrensk\u00e9m pr\u016fmyslu.<\/p>\n

Jedine\u010dn\u00e1 kombinace stabiln\u00edch chemick\u00fdch vlastnost\u00ed, vynikaj\u00edc\u00ed tepeln\u00e9 vodivosti, n\u00edzk\u00e9ho koeficientu tepeln\u00e9 rozta\u017enosti, tvrdosti a mechanick\u00e9 pevnosti karbidu k\u0159em\u00edku vedla k jeho \u0161irok\u00e9mu vyu\u017eit\u00ed v n\u011bkolika pr\u016fmyslov\u00fdch odv\u011btv\u00edch, v\u010detn\u011b ropn\u00e9ho pr\u016fmyslu, chemick\u00e9ho in\u017een\u00fdrstv\u00ed, mikroelektroniky, automobilov\u00e9ho pr\u016fmyslu, leteck\u00e9 pap\u00edrensk\u00e9 v\u00fdroby a laserov\u00e9 t\u011b\u017eby. Krom\u011b toho karbid k\u0159em\u00edku nach\u00e1z\u00ed uplatn\u011bn\u00ed tak\u00e9 v informa\u010dn\u00ed elektronice na ochranu \u017eivotn\u00edho prost\u0159ed\u00ed a v aplikac\u00edch pro vyu\u017eit\u00ed energie.<\/p>\n

Karbid k\u0159em\u00edku (SiC) lze vyr\u00e1b\u011bt dv\u011bma procesy, reak\u010dn\u00edm spojov\u00e1n\u00edm a sp\u00e9k\u00e1n\u00edm, p\u0159i\u010dem\u017e oba tyto procesy ovliv\u0148uj\u00ed jeho kone\u010dnou mikrostrukturu. Reak\u010dn\u011b v\u00e1zan\u00fd SiC se obvykle vytv\u00e1\u0159\u00ed infiltrac\u00ed kompakt\u016f tvo\u0159en\u00fdch sm\u011bs\u00ed k\u0159em\u00edku a uhl\u00edku kapaln\u00fdm k\u0159em\u00edkem, kter\u00fd pak reaguje s dal\u0161\u00edmi molekulami k\u0159em\u00edku a uhl\u00edku za vzniku dal\u0161\u00edch vazeb SiC, zat\u00edmco sp\u00e9kan\u00fd SiC se vyr\u00e1b\u00ed pomoc\u00ed b\u011b\u017en\u00fdch technik tv\u00e1\u0159en\u00ed keramiky a neoxidov\u00fdch sp\u00e9kac\u00edch pom\u016fcek pro v\u00fdrobu.<\/p>\n

Karbid k\u0159em\u00edku je d\u00edky sv\u00e9 vynikaj\u00edc\u00ed obrobitelnosti vynikaj\u00edc\u00edm materi\u00e1lem pro v\u00fdrobu t\u011bsnic\u00edch sou\u010d\u00e1st\u00ed odoln\u00fdch proti opot\u0159eben\u00ed, zejm\u00e9na v kombinaci s grafitem. Tato kombinace nab\u00edz\u00ed ni\u017e\u0161\u00ed koeficienty t\u0159en\u00ed ne\u017e korundov\u00e1 keramika a tvrd\u00e9 slitiny a zachov\u00e1v\u00e1 sv\u016fj tvar p\u0159i vysok\u00fdch hodnot\u00e1ch PV, aby se zabr\u00e1nilo \u00faniku chemik\u00e1li\u00ed, jako jsou louhy a kyseliny, do \u017eivotn\u00edho prost\u0159ed\u00ed.<\/p>\n

\"reakce<\/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\/cs\/wp-json\/wp\/v2\/posts\/23","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/siliconcarbideceramic.net\/cs\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/siliconcarbideceramic.net\/cs\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/siliconcarbideceramic.net\/cs\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/siliconcarbideceramic.net\/cs\/wp-json\/wp\/v2\/comments?post=23"}],"version-history":[{"count":3,"href":"https:\/\/siliconcarbideceramic.net\/cs\/wp-json\/wp\/v2\/posts\/23\/revisions"}],"predecessor-version":[{"id":29,"href":"https:\/\/siliconcarbideceramic.net\/cs\/wp-json\/wp\/v2\/posts\/23\/revisions\/29"}],"wp:attachment":[{"href":"https:\/\/siliconcarbideceramic.net\/cs\/wp-json\/wp\/v2\/media?parent=23"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/siliconcarbideceramic.net\/cs\/wp-json\/wp\/v2\/categories?post=23"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/siliconcarbideceramic.net\/cs\/wp-json\/wp\/v2\/tags?post=23"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}