Struktuurikeraamika, mida nimetatakse ka tehnokeraamikaks, on t\u00e4iustatud keraamika klass, mis avaldab peamiselt materjalide mehaanilist, termilist, keemilist ja muud m\u00f5ju. Struktuurikeraamika omadused on k\u00f5rge temperatuurikindlus, kulumiskindlus, korrosioonikindlus, oks\u00fcdatsioonikindlus ja v\u00e4hene roomavus k\u00f5rge temperatuuri all. Nad suudavad vastu pidada karmile t\u00f6\u00f6keskkonnale, milleks metallmaterjalid ja pol\u00fcmeermaterjalid ei ole p\u00e4devad. Neid kasutatakse laialdaselt lennunduses, masinat\u00f6\u00f6stuses, autot\u00f6\u00f6stuses, metallurgias, keemiat\u00f6\u00f6stuses, elektroonikas ja muudes valdkondades ning neist on saanud keraamiliste materjalide klass, mis areneb v\u00e4ga kiiresti.Struktuurikeraamika h\u00f5lmab peamiselt oksiidkeraamikat, nitriidkeraamikat ja karbiidkeraamikat. Allpool tutvustatakse peamiselt r\u00e4nikarbiidkeraamikat. R\u00e4nikarbiid, \u00fcldtuntud kui karborund, tuntud ka kui karborund, on t\u00fc\u00fcpiline kovalentsete sidemetega \u00fchend, mida looduses peaaegu ei eksisteeri. Kui Eword ja G. Acheson tahtsid 1890. aastal s\u00fcnteesida teemanti, lisades s\u00fcsinikule katal\u00fcsaatorina r\u00e4ni, valmistasid nad r\u00e4nikarbiidi. T\u00e4nap\u00e4eval uuritakse ja arendatakse seda endiselt.<\/p>\n
R\u00e4nikarbiidi kasutati algselt selle \u00fclik\u00f5va toimivuse t\u00f5ttu, mida saab valmistada erinevateks lihvketasteks, abrasiivkangasteks, abrasiivpaberiks ja mitmesugusteks abrasiivideks ning mida kasutatakse laialdaselt mehaanilise t\u00f6\u00f6tlemise t\u00f6\u00f6stuses. Teises maailmas\u00f5jas leiti, et r\u00e4nikarbiidkeraamikat saab kasutada ka redutseerijana ja k\u00fctteelemendina terasetootmises, mis soodustas selle kiiret arengut. Edasiste uuringutega leiti, et sellel on palju suurep\u00e4raseid omadusi, n\u00e4iteks k\u00f5rge temperatuuristabiilsus, k\u00f5rge soojusjuhtivus, happekindlus ja leeliskorrosioonikindlus, madal paisumiskoefitsient ja hea termilise \u0161oki vastupidavus.<\/p>\n
R\u00e4nikarbiidil on peamiselt kaks kristallvormi, nimelt: kuubiline \u03b2- SIC4 ja heksagonaalne \u03b1- SIC\u3002 R\u00e4nikarbiidi v\u00f5re p\u00f5hilised struktuuri\u00fcksused on \u00fcksteist l\u00e4bivad SIC4 ja CSI4 tetraeedrid. Tetraeedrid jagavad sama serva, et moodustada tasapinnaline kiht, ja tipud on \u00fchendatud j\u00e4rgmise tetraeedrikihiga, et moodustada kolmem\u00f5\u00f5tmeline mehhanism. Kuna erinevad tetraeedrite virnastamise j\u00e4rjestused v\u00f5ivad moodustada erinevaid struktuure, on seni leitud sadu variante. \u00dcldiselt kasutatakse l\u00fchikesi ja intuitiivseid s\u00fcmboleid, nimelt t\u00e4hti C, H, R, v\u00f5restiku t\u00fc\u00fcbi t\u00e4histamiseks ning erinevuse n\u00e4itamiseks kasutatakse \u00fchikrakus sisalduvate kihtide arvu. Kuigi nende pol\u00fcmorfide v\u00f5rekonstandid on erinevad, ei ole neis esinevad ained ilmselgelt muutunud. r\u00e4nikarbiidkeraamika on t\u00fc\u00fcpiline valentsi\u00fchend, kuid on olemas ka m\u00f5ned ioonsed t\u00fc\u00fcbid. Teoreetiliste arvutuste kohaselt kuulub SI-C sideme koguenergiast 78% kovalentsesse olekusse ja 22% ioonilisse olekusse. S- ja C- aatomite v\u00e4ikese suuruse, sideme pikkuse ja tugeva kovalentsuse t\u00f5ttu on r\u00e4nikarbiidkeraamikal rida omadusi, n\u00e4iteks suur k\u00f5vadus, teatav mehaaniline tugevus ja raske paagutamine.<\/p>\n
R\u00e4nikarbiid on t\u00fc\u00fcpiline kovalentsete sidemetega seotud stabiilne \u00fchend. Lisaks on selle difusioonikoefitsient madal, mist\u00f5ttu on seda raske tihendada tavap\u00e4raste paagutusmeetoditega. Tiheda r\u00e4nikarbiidkeraamika saamiseks on vaja lisada m\u00f5ningaid paagutamise abiaineid, et suurendada pinnaenergiat v\u00f5i pindala, ning v\u00f5tta kasutusele eriprotseduurid. Vastavalt paagutusprotsessile v\u00f5ib r\u00e4nikarbiidi jagada \u00fcmberkristalliseeritud r\u00e4nikarbiidkeraamika, reaktsioonis paagutatud r\u00e4nikarbiidkeraamika, surveta paagutatud r\u00e4nikarbiidkeraamika, kuumpressitud paagutatud r\u00e4nikarbiidkeraamika, k\u00f5rge temperatuuriga kuuma isostaatilise pressimisega paagutatud r\u00e4nikarbiidkeraamika ja keemilise aurustamise r\u00e4nikarbiidiks. Erinevate protsesside abil valmistatud r\u00e4nikarbiidi omadused on \u00fcsna erinevad, st sama protsessi abil valmistatud r\u00e4nikarbiidi omadused on erinevate toorainete ja lisandite t\u00f5ttu halvad.<\/p>","protected":false},"excerpt":{"rendered":"
Structural ceramics, also known as engineering ceramics, are a class of advanced ceramics that mainly exert the mechanical, thermal, chemical […]<\/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-7","post","type-post","status-publish","format-standard","hentry","category-product-related"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/siliconcarbideceramic.net\/et\/wp-json\/wp\/v2\/posts\/7","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/siliconcarbideceramic.net\/et\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/siliconcarbideceramic.net\/et\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/siliconcarbideceramic.net\/et\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/siliconcarbideceramic.net\/et\/wp-json\/wp\/v2\/comments?post=7"}],"version-history":[{"count":4,"href":"https:\/\/siliconcarbideceramic.net\/et\/wp-json\/wp\/v2\/posts\/7\/revisions"}],"predecessor-version":[{"id":11,"href":"https:\/\/siliconcarbideceramic.net\/et\/wp-json\/wp\/v2\/posts\/7\/revisions\/11"}],"wp:attachment":[{"href":"https:\/\/siliconcarbideceramic.net\/et\/wp-json\/wp\/v2\/media?parent=7"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/siliconcarbideceramic.net\/et\/wp-json\/wp\/v2\/categories?post=7"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/siliconcarbideceramic.net\/et\/wp-json\/wp\/v2\/tags?post=7"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}