Ceramica structural\u0103, cunoscut\u0103 \u0219i sub denumirea de ceramic\u0103 tehnic\u0103, este o clas\u0103 de ceramic\u0103 avansat\u0103 care exercit\u0103 \u00een principal efectele mecanice, termice, chimice \u0219i alte efecte ale materialelor. Ceramica structural\u0103 are propriet\u0103\u021bi de rezisten\u021b\u0103 la temperaturi ridicate, rezisten\u021b\u0103 la uzur\u0103, rezisten\u021b\u0103 la coroziune, rezisten\u021b\u0103 la oxidare \u0219i fluaj sc\u0103zut la temperaturi ridicate. Ele pot rezista mediului de lucru dur pentru care materialele metalice \u0219i materialele polimerice nu sunt competente. Acestea sunt utilizate pe scar\u0103 larg\u0103 \u00een avia\u021bie, ma\u0219ini, automobile, metalurgie, industria chimic\u0103, electronic\u0103 \u0219i alte domenii \u0219i au devenit o clas\u0103 de materiale ceramice care se dezvolt\u0103 foarte rapid. ceramica structural\u0103 include \u00een principal ceramic\u0103 de oxid, ceramic\u0103 de nitrur\u0103 \u0219i ceramic\u0103 de carbur\u0103. Ceramica carbur\u0103 de siliciu este prezentat\u0103 \u00een principal mai jos. Carbura de siliciu, cunoscut\u0103 \u00een mod obi\u0219nuit sub numele de carborundum, cunoscut\u0103 \u0219i sub numele de carborundum, este un compus tipic cu leg\u0103turi covalente care aproape c\u0103 nu exist\u0103 \u00een natur\u0103. \u00cen 1890, c\u00e2nd Eword \u0219i G. Acheson au dorit s\u0103 sintetizeze diamantul prin ad\u0103ugarea de siliciu \u00een carbon ca un catalizator, au preparat carbur\u0103 de siliciu. Ast\u0103zi, acesta este \u00eenc\u0103 studiat \u0219i dezvoltat.<\/p>\n
Carbura de siliciu a fost utilizat\u0103 ini\u021bial datorit\u0103 performan\u021bei sale foarte dure, care poate fi transformat\u0103 \u00een diverse discuri abrazive, \u021bes\u0103turi abrazive, h\u00e2rtie abraziv\u0103 \u0219i diver\u0219i abrazivi \u0219i este utilizat\u0103 pe scar\u0103 larg\u0103 \u00een industria prelucr\u0103rii mecanice. \u00cen timpul celui de-al Doilea R\u0103zboi Mondial, s-a constatat c\u0103 ceramica din carbur\u0103 de siliciu poate fi utilizat\u0103 \u0219i ca agent de reducere \u0219i element de \u00eenc\u0103lzire \u00een produc\u021bia de o\u021bel, promov\u00e2nd astfel dezvoltarea sa rapid\u0103. \u00cen urma cercet\u0103rilor ulterioare, s-a constatat c\u0103 are multe propriet\u0103\u021bi excelente, cum ar fi stabilitatea la temperaturi ridicate, conductivitatea termic\u0103 ridicat\u0103, rezisten\u021ba la coroziunea acid\u0103 \u0219i alcalin\u0103, coeficientul de dilatare sc\u0103zut \u0219i rezisten\u021ba bun\u0103 la \u0219ocurile termice.<\/p>\n
Exist\u0103 \u00een principal dou\u0103 forme cristaline de carbur\u0103 de siliciu, \u0219i anume: cubic\u0103 \u03b2- SIC4 \u0219i hexagonal\u0103 \u03b1- SIC\u3002 Unit\u0103\u021bile structurale de baz\u0103 ale re\u021belei de carbur\u0103 de siliciu sunt tetraedrele SIC4 \u0219i CSI4 care se \u00eentrep\u0103trund reciproc. Tetraedrele \u00eempart aceea\u0219i muchie pentru a forma un strat plan, iar v\u00e2rfurile sunt conectate cu urm\u0103torul strat de tetraedre pentru a forma un mecanism tridimensional. Deoarece secven\u021be diferite de stivuire a tetraedrelor pot forma structuri diferite, p\u00e2n\u0103 \u00een prezent au fost g\u0103site sute de variante. \u00cen general, se utilizeaz\u0103 simboluri concise \u0219i intuitive, \u0219i anume literele C, H, R, pentru a reprezenta tipul de re\u021bea, iar num\u0103rul de straturi con\u021binute \u00een celula unitar\u0103 este utilizat pentru a ar\u0103ta diferen\u021ba. De\u0219i constantele de re\u021bea ale acestor polimorfe sunt diferite, nu exist\u0103 nicio schimbare evident\u0103 \u00een ceea ce prive\u0219te substan\u021bele din ele. ceramica din carbur\u0103 de siliciu este un compus de valen\u021b\u0103 tipic, dar exist\u0103 \u0219i unele tipuri ionice. Conform calculelor teoretice, 78% din energia total\u0103 a leg\u0103turii SI-C apar\u021bine st\u0103rii covalente \u0219i 22% apar\u021bine st\u0103rii ionice. Datorit\u0103 dimensiunii mici a atomilor S \u0219i C, a lungimii leg\u0103turii \u0219i a covalen\u021bei puternice, ceramica din carbur\u0103 de siliciu are o serie de caracteristici, cum ar fi duritatea ridicat\u0103, o anumit\u0103 rezisten\u021b\u0103 mecanic\u0103 \u0219i sinterizarea dificil\u0103.<\/p>\n
Carbura de siliciu este un compus tipic stabil legat prin leg\u0103turi covalente. \u00cen plus, coeficientul s\u0103u de difuzie este sc\u0103zut, ceea ce \u00eel face dificil de densificat prin metode conven\u021bionale de sinterizare. Este necesar\u0103 ad\u0103ugarea unor adjuvan\u021bi de sinterizare pentru a cre\u0219te energia de suprafa\u021b\u0103 sau aria de suprafa\u021b\u0103 \u0219i adoptarea unor procese speciale pentru a ob\u021bine ceramic\u0103 dens\u0103 din carbur\u0103 de siliciu. \u00cen func\u021bie de procesul de sinterizare, carbura de siliciu poate fi \u00eemp\u0103r\u021bit\u0103 \u00een ceramic\u0103 de carbur\u0103 de siliciu recristalizat\u0103, ceramic\u0103 de carbur\u0103 de siliciu sinterizat\u0103 prin reac\u021bie, ceramic\u0103 de carbur\u0103 de siliciu sinterizat\u0103 f\u0103r\u0103 presiune, ceramic\u0103 de carbur\u0103 de siliciu sinterizat\u0103 prin presare la cald, ceramic\u0103 de carbur\u0103 de siliciu sinterizat\u0103 prin presare izostatic\u0103 la cald la temperatur\u0103 ridicat\u0103 \u0219i carbur\u0103 de siliciu prin depunere de vapori chimici. Propriet\u0103\u021bile carburii de siliciu preparate prin diferite procese sunt destul de diferite, adic\u0103 SIC preparat\u0103 prin acela\u0219i proces are performan\u021be slabe din cauza diferitelor materii prime \u0219i aditivi.<\/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\/ro\/wp-json\/wp\/v2\/posts\/7","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/siliconcarbideceramic.net\/ro\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/siliconcarbideceramic.net\/ro\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/siliconcarbideceramic.net\/ro\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/siliconcarbideceramic.net\/ro\/wp-json\/wp\/v2\/comments?post=7"}],"version-history":[{"count":4,"href":"https:\/\/siliconcarbideceramic.net\/ro\/wp-json\/wp\/v2\/posts\/7\/revisions"}],"predecessor-version":[{"id":11,"href":"https:\/\/siliconcarbideceramic.net\/ro\/wp-json\/wp\/v2\/posts\/7\/revisions\/11"}],"wp:attachment":[{"href":"https:\/\/siliconcarbideceramic.net\/ro\/wp-json\/wp\/v2\/media?parent=7"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/siliconcarbideceramic.net\/ro\/wp-json\/wp\/v2\/categories?post=7"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/siliconcarbideceramic.net\/ro\/wp-json\/wp\/v2\/tags?post=7"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}