Beztlakov\u00e9 spekanie karbidu krem\u00edka sa pova\u017euje za najs\u013eubnej\u0161\u00ed spekan\u00fd karbid krem\u00edka a beztlakov\u00fdm spekan\u00edm mo\u017eno pripravi\u0165 zlo\u017eit\u00e9 tvary a ve\u013ek\u00e9 rozmery keramiky z karbidu krem\u00edka. V z\u00e1vislosti od mechanizmu spekania mo\u017eno tento druh spekan\u00e9ho karbidu krem\u00edka \u010falej rozdeli\u0165 na spekanie v pevnej f\u00e1ze a spekanie v kvapalnej f\u00e1ze. \u03b2-SiC obsahuj\u00faci stopov\u00e9 mno\u017estv\u00e1 SiO sa m\u00f4\u017ee spiec\u0165 pri atmosf\u00e9rickom tlaku pridan\u00edm B a C. T\u00e1to met\u00f3da v\u00fdrazne zlep\u0161uje kinetiku spekania karbidu krem\u00edka. Po pridan\u00ed vhodn\u00e9ho mno\u017estva B sa B po\u010das spekania nach\u00e1dza na hraniciach z\u0155n SiC a \u010diasto\u010dne tvor\u00ed pevn\u00fd roztok s SiC, \u010d\u00edm sa zni\u017euje energia na hraniciach z\u0155n SiC. Dopovanie mierneho mno\u017estva vo\u013en\u00e9ho C je v\u00fdhodn\u00e9 pre spekanie v pevnej f\u00e1ze, preto\u017ee povrch SiC je zvy\u010dajne oxidovan\u00fd s mal\u00fdm mno\u017estvom tvorby SiO a pr\u00eddavok mierneho mno\u017estva C pom\u00e1ha, aby sa film SiO na povrchu SiC zredukoval a odstr\u00e1nil, \u010d\u00edm sa zvy\u0161uje povrchov\u00e1 energia. Spekanie v kvapalnej f\u00e1ze v\u0161ak bude ma\u0165 negat\u00edvny \u00fa\u010dinok, preto\u017ee C bude reagova\u0165 s oxidov\u00fdmi pr\u00edsadami za vzniku plynu, vzniku ve\u013ek\u00e9ho po\u010dtu otvorov v keramickom spekanom telese, \u010do ovplyvn\u00ed proces zhut\u0148ovania. \u010cistota, jemnos\u0165 a f\u00e1zov\u00e9 zlo\u017eenie suroviny s\u00fa ve\u013emi d\u00f4le\u017eit\u00e9 v procese spekania karbidu krem\u00edka. s. Proehazka spekal spekan\u00fd karbid krem\u00edka s hustotou vy\u0161\u0161ou ako 98% pri teplote 2020 \u00b0C za atmosf\u00e9rick\u00e9ho tlaku s\u00fa\u010dasn\u00fdm pridan\u00edm vhodn\u00fdch mno\u017estiev B a C do ultrajemn\u00fdch pr\u00e1\u0161kov \u03b2-SiC (obsahuj\u00facich menej ako 2% kysl\u00edka). Syst\u00e9m SiC-B-C v\u0161ak patr\u00ed do kateg\u00f3rie spekania v pevnej f\u00e1ze, ktor\u00e9 si vy\u017eaduje vysok\u00fa teplotu spekania a n\u00edzku lomov\u00fa h\u00fa\u017eevnatos\u0165, lomov\u00fd re\u017eim je typick\u00fd lom cez kry\u0161t\u00e1l, hrub\u00e9 zrn\u00e1 a slab\u00e1 rovnomernos\u0165. Zahrani\u010dn\u00fd v\u00fdskum SiC sa s\u00fastre\u010fuje najm\u00e4 na spekanie v kvapalnej f\u00e1ze, t. j. ur\u010dit\u00fd po\u010det spekac\u00edch pr\u00edsad, pri ni\u017e\u0161ej teplote, aby sa dosiahlo zhutnenie SiC. Spekanie SiC v kvapalnej f\u00e1ze nielen zni\u017euje teplotu spekania v porovnan\u00ed so spekan\u00edm v pevnej f\u00e1ze, ale zlep\u0161uje aj mikro\u0161trukt\u00faru, a t\u00fdm sa zlep\u0161uj\u00fa vlastnosti spekan\u00e9ho telesa v porovnan\u00ed s vlastnos\u0165ami spekan\u00e9ho telesa v pevnej f\u00e1ze.
\nM. Omori a kol. pou\u017eili na hust\u00e9 spekanie SiC oxidy vz\u00e1cnych zem\u00edn v zmesi s AlO alebo boridmi. Na druhej strane Suzuki spekal SiC len s AlO ako pr\u00edsadou pri teplote pribli\u017ene 2 000 \u00b0C. A. Mulla a kol. spekali 0,5 \u03bcm \u03b2-SiC (s mal\u00fdm mno\u017estvom SiO na povrchu \u010dast\u00edc) s AlO a YO ako pr\u00edsadami pri ,1850-1950 \u00b0C a z\u00edskali relat\u00edvnu hustotu keramiky SiC, ktor\u00e1 bola v\u00e4\u010d\u0161ia ako 95% teoretickej hustoty, a zrn\u00e1 boli jemn\u00e9, s priemernou ve\u013ekos\u0165ou 1,5 \u03bcm.
\nZistilo sa, \u017ee mikro\u0161trukt\u00fara keramiky z karbidu krem\u00edka m\u00e1 hrub\u00e9 zrn\u00e1 a ty\u010dinkovit\u00fa \u0161trukt\u00faru s dobrou lomovou h\u00fa\u017eevnatos\u0165ou. Ty\u010dinkovit\u00e9 zrn\u00e1 zvy\u0161uj\u00fa lomov\u00fa h\u00fa\u017eevnatos\u0165 a z\u00e1rove\u0148 zni\u017euj\u00fa pevnos\u0165 keramiky z karbidu krem\u00edka. S cie\u013eom dosiahnu\u0165 lep\u0161iu pevnos\u0165 a h\u00fa\u017eevnatos\u0165 pri s\u00fa\u010dasnom zn\u00ed\u017een\u00ed teploty spekania sa uskuto\u010dnilo mnoho pokusov o zlep\u0161enie vlastnost\u00ed tohto spekan\u00e9ho karbidu krem\u00edka \u00fapravou zlo\u017eenia sklenej f\u00e1zy pomocou r\u00f4znych pr\u00edsad. Po\u010das procesu spekania viedlo zavedenie kvapalnej f\u00e1zy na hranici z\u0155n a jedine\u010dn\u00e1 medzif\u00e1zov\u00e1 \u0161trukt\u00fara k oslabeniu medzif\u00e1zovej \u0161trukt\u00fary a lom materi\u00e1lu sa zmenil na \u00fapln\u00fd pozd\u013a\u017eny lom, \u010do viedlo k v\u00fdrazn\u00e9mu zv\u00fd\u0161eniu pevnosti a h\u00fa\u017eevnatosti materi\u00e1lu. Av\u0161ak vzh\u013eadom na to, \u017ee pri pou\u017eit\u00ed pr\u00edsady AlO vznik\u00e1 sklovit\u00e1 f\u00e1za s n\u00edzkym bodom topenia a vysokou prchavos\u0165ou, ktor\u00e1 pri vy\u0161\u0161\u00edch teplot\u00e1ch podlieha siln\u00e9mu vyparovaniu, \u010do sp\u00f4sobuje \u00fabytok hmotnosti materi\u00e1lu a nepriaznivo ovplyv\u0148uje zhutnenie materi\u00e1lu, hmotnostn\u00fd podiel AlO v pr\u00edsade by sa mal primerane zv\u00fd\u0161i\u0165.<\/p>","protected":false},"excerpt":{"rendered":"
Beztlakov\u00e9 spekanie karbidu krem\u00edka sa pova\u017euje za najs\u013eubnej\u0161\u00ed spekan\u00fd karbid krem\u00edka a beztlakov\u00fdm spekan\u00edm mo\u017eno pripravi\u0165 zlo\u017eit\u00e9 tvary a ve\u013ek\u00e9 rozmery keramiky z karbidu krem\u00edka. V z\u00e1vislosti od mechanizmu spekania mo\u017eno tento druh spekan\u00e9ho karbidu krem\u00edka \u010falej rozdeli\u0165 na spekanie v pevnej f\u00e1ze a spekanie v kvapalnej f\u00e1ze. \u03b2-SiC obsahuj\u00faci... <\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"neve_meta_sidebar":"","neve_meta_container":"","neve_meta_enable_content_width":"","neve_meta_content_width":0,"neve_meta_title_alignment":"","neve_meta_author_avatar":"","neve_post_elements_order":"","neve_meta_disable_header":"","neve_meta_disable_footer":"","neve_meta_disable_title":"","ngg_post_thumbnail":0,"footnotes":""},"categories":[30],"tags":[],"class_list":["post-578","post","type-post","status-publish","format-standard","hentry","category-sic-knowledge"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/siliconcarbide.net\/sk\/wp-json\/wp\/v2\/posts\/578","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/siliconcarbide.net\/sk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/siliconcarbide.net\/sk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/siliconcarbide.net\/sk\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/siliconcarbide.net\/sk\/wp-json\/wp\/v2\/comments?post=578"}],"version-history":[{"count":1,"href":"https:\/\/siliconcarbide.net\/sk\/wp-json\/wp\/v2\/posts\/578\/revisions"}],"predecessor-version":[{"id":579,"href":"https:\/\/siliconcarbide.net\/sk\/wp-json\/wp\/v2\/posts\/578\/revisions\/579"}],"wp:attachment":[{"href":"https:\/\/siliconcarbide.net\/sk\/wp-json\/wp\/v2\/media?parent=578"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/siliconcarbide.net\/sk\/wp-json\/wp\/v2\/categories?post=578"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/siliconcarbide.net\/sk\/wp-json\/wp\/v2\/tags?post=578"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}