Carbura de siliciu sau carborundul () este o ceramic\u0103 dur\u0103 produs\u0103 \u00een mas\u0103 pentru prima dat\u0103 \u00een 1893 pentru a fi utilizat\u0103 ca abraziv. De\u0219i exist\u0103 cazuri naturale (pietre pre\u021bioase din moissanit \u0219i cantit\u0103\u021bi mici sub form\u0103 de roc\u0103 \u00edgnea numit\u0103 corindon), cea mai mare parte a utiliz\u0103rii moderne se face pe cale sintetic\u0103.<\/p>\n
SiC este cunoscut pentru c\u0103 prezint\u0103 o rezisten\u021b\u0103 ridicat\u0103 la oboseal\u0103, o conductivitate termic\u0103 ridicat\u0103 \u0219i un coeficient de dilatare sc\u0103zut, ceea ce \u00eel face potrivit pentru a rezista la temperaturi ridicate, r\u0103m\u00e2n\u00e2nd \u00een acela\u0219i timp puternic \u00een medii corozive.<\/p>\n
Carbura de siliciu este unul dintre pu\u021binele materiale cu o conductivitate termic\u0103 ridicat\u0103 la temperatura camerei. Datorit\u0103 naturii sale dure, rigide \u0219i stabile la temperatur\u0103, carbura de siliciu este un material excelent pentru oglinzile telescoapelor folosite de astronomi.<\/p>\n
Teoria func\u021bional\u0103 a densit\u0103\u021bii a fost utilizat\u0103 pentru investiga\u021bii teoretice sistematice ale parametrilor structurali \u0219i ale propriet\u0103\u021bilor termofizice la temperatur\u0103 finit\u0103 ale carburii de siliciu cubice (3C-SiC). Rezultatele noastre privind constantele elastice \u0219i microdure\u021bea Knoop au ar\u0103tat o concordan\u021b\u0103 satisf\u0103c\u0103toare cu datele experimentale, precum \u0219i cu rezultatele calculate publicate \u00een alt\u0103 parte.<\/p>\n
Prin utilizarea modelelor de structur\u0103 optimizate, am ob\u021binut, de asemenea, estim\u0103ri la nivel atomic ale energiilor de formare a defectelor pentru ZrC, TiC \u0219i SiC folosind modele de structur\u0103 optimizate. Rezultatele au ar\u0103tat c\u0103 temperatura Debye scade odat\u0103 cu cre\u0219terea num\u0103rului de atomi de defect, \u00een timp ce defectele CZr antisite \u0219i VC prezint\u0103 energii de formare mai mici dec\u00e2t defectele lor omologe VSi \u0219i Sit; reducerea energiei de formare a acestora poate avea un impact asupra rezisten\u021bei la deformarea uniaxial\u0103 \u0219i de forfecare a structurilor 3C-SiC.<\/p>\n
Carbura de siliciu este unul dintre cele mai dure \u0219i mai termo-conductoare materiale din natur\u0103, rezistent\u0103 at\u00e2t la atacul acizilor, c\u00e2t \u0219i la cel al alcalinelor, fiind \u00een acela\u0219i timp rezistent\u0103 la temperaturi de p\u00e2n\u0103 la 1600 de grade Celsius, f\u0103r\u0103 pierdere de rezisten\u021b\u0103. \u00cen plus, carbura de siliciu este un excelent conductor electric.<\/p>\n
Bandgap-ul larg al carburii de siliciu o face potrivit\u0103 pentru utilizarea \u00een dispozitive semiconductoare precum diode, tranzistoare \u0219i tiristoare, \u00een timp ce capacitatea sa de a rezista la tensiuni \u0219i curen\u021bi mari o face util\u0103 \u0219i \u00een dispozitivele de putere mare.<\/p>\n
SiC poros poate fi modificat prin ad\u0103ugarea de nanoplachete de grafen (GNP), cre\u00e2nd un material cu propriet\u0103\u021bi termice \u00eembun\u0103t\u0103\u021bite. Acest material poate fi fabricat prin sinterizarea cu plasm\u0103 cu sc\u00e2ntei \u00een faz\u0103 lichid\u0103 a pulberii de SiC stoichiometrice sau nestoichiometrice; au fost testate diferite combina\u021bii de adjuvan\u021bi de sinterizare (Y2O3 \u0219i La2O3) pentru a evalua efectele acestora asupra compozi\u021biei fazelor, microstructurii \u0219i conductivit\u0103\u021bii termice a materialelor poroase cu un con\u021binut de GNP-uri de p\u00e2n\u0103 la 20 vol%; a fost observat\u0103 o dependen\u021b\u0103 nemonoton\u0103 de temperatur\u0103 \u00een cazul compozitelor care con\u021bin un con\u021binut de GNP-uri de p\u00e2n\u0103 la 20%.<\/p>\n
Compozi\u021bia unic\u0103 de atomi de siliciu \u0219i de carbon din re\u021beaua cristalin\u0103 a SiC \u00eei confer\u0103 propriet\u0103\u021bi mecanice remarcabile care \u00eel fac unul dintre cele mai dure \u0219i mai rezistente materiale ceramice. Extrem de rezistent la coroziunea provocat\u0103 de acizi, le\u0219ie, s\u0103ruri topite, precum \u0219i la abraziune; rigiditatea \u0219i rezisten\u021ba fac din SiC o alegere atractiv\u0103 de material pentru componente rezistente la uzur\u0103, cum ar fi discurile de rectificat sau burghiele din mori, expandatoare sau extrudatoare.<\/p>\n
Pe l\u00e2ng\u0103 faptul c\u0103 este u\u0219or, materialul ceramic prezint\u0103 o rezisten\u021b\u0103 excelent\u0103 la \u0219ocurile termice - poate suporta temperaturi de p\u00e2n\u0103 la 1600degC f\u0103r\u0103 a-\u0219i pierde propriet\u0103\u021bile mecanice sau expansiunea termic\u0103, cu rate sc\u0103zute de expansiune termic\u0103 \u0219i un modul Young excep\u021bional de ridicat care asigur\u0103 stabilitate dimensional\u0103.<\/p>\n
Porozitatea ceramicii SiC poroase variaz\u0103 \u00een func\u021bie de metoda de formare a acestora (lipire prin reac\u021bie sau sinterizare). Studiile au demonstrat c\u0103 at\u00e2t conductivitatea electric\u0103, c\u00e2t \u0219i rezisten\u021ba la flexiune cresc odat\u0103 cu cre\u0219terea con\u021binutului de B4C, datorit\u0103 capacit\u0103\u021bii sale de a adsorbi oxigenul din materialele cu matrice Si-C \u0219i, astfel, de a reduce lungimea de dispersie a fononilor.<\/p>\n
Carbura de siliciu este utilizat\u0103 at\u00e2t ca abraziv, c\u00e2t \u0219i ca unealt\u0103 de t\u0103iere \u00een produc\u021bie. Datorit\u0103 suprafe\u021bei sale dure \u0219i rezistente la c\u0103ldur\u0103, carbura de siliciu poate fi folosit\u0103 \u0219i ca semiconductor electronic \u00een diode \u0219i tranzistori, deoarece toleran\u021ba sa la tensiune o poate dep\u0103\u0219i pe cea a siliciului.<\/p>\n
Duritatea carburii de siliciu, rezisten\u021ba la coroziune \u0219i conductivitatea termic\u0103 ridicat\u0103 fac din ea un material excelent pentru echipamentele de protec\u021bie, cum ar fi c\u0103\u0219tile \u0219i pl\u0103cile de armur\u0103. \u00cen plus, iner\u021bia sa chimic\u0103 \u00eenseamn\u0103 c\u0103 nu reac\u021bioneaz\u0103 cu apa, ceea ce \u00eel face ideal pentru utilizarea \u00een medii cu umiditate ridicat\u0103, cum ar fi navele spa\u021biale \u0219i mediile marine.<\/p>\n
Carbura de siliciu recristalizat (RSiC) se m\u00e2ndre\u0219te cu un amestec de propriet\u0103\u021bi mecanice, termice \u0219i electrice de neegalat fa\u021b\u0103 de orice alt\u0103 variant\u0103 de SiC. Microstructura sa dens\u0103 confer\u0103 RSiC un coeficient de dilatare sc\u0103zut, men\u021bin\u00e2nd \u00een acela\u0219i timp rezisten\u021ba \u0219i rigiditatea la temperaturi ridicate; \u00een plus, prezint\u0103 valori relativ mai mari ale modulului de elasticitate dec\u00e2t ceramica structural\u0103 de zirconiu \u0219i are valori sc\u0103zute ale coeficientului de dilatare termic\u0103 \u00een compara\u021bie cu ceramica structural\u0103 de zirconiu.<\/p>","protected":false},"excerpt":{"rendered":"
Silicon carbide, or carborundum (), is a hard ceramic first mass-produced in 1893 for use as an abrasive. While natural instances exist (moissanite gems and small quantities as an igneous rock called corundum), most modern day usage occurs synthetically. SiC is known to exhibit high fatigue resistance, high thermal conductivity and a low coefficient of […]<\/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-190","post","type-post","status-publish","format-standard","hentry","category-knowledge"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/ceramicatijolart.com\/ro\/wp-json\/wp\/v2\/posts\/190","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ceramicatijolart.com\/ro\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ceramicatijolart.com\/ro\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ceramicatijolart.com\/ro\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ceramicatijolart.com\/ro\/wp-json\/wp\/v2\/comments?post=190"}],"version-history":[{"count":1,"href":"https:\/\/ceramicatijolart.com\/ro\/wp-json\/wp\/v2\/posts\/190\/revisions"}],"predecessor-version":[{"id":191,"href":"https:\/\/ceramicatijolart.com\/ro\/wp-json\/wp\/v2\/posts\/190\/revisions\/191"}],"wp:attachment":[{"href":"https:\/\/ceramicatijolart.com\/ro\/wp-json\/wp\/v2\/media?parent=190"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ceramicatijolart.com\/ro\/wp-json\/wp\/v2\/categories?post=190"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ceramicatijolart.com\/ro\/wp-json\/wp\/v2\/tags?post=190"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}