Beztlakov\u00e9 slinov\u00e1n\u00ed karbidu k\u0159em\u00edku je pova\u017eov\u00e1no za nejslibn\u011bj\u0161\u00ed slinov\u00e1n\u00ed karbidu k\u0159em\u00edku a beztlakov\u00fdm slinov\u00e1n\u00edm lze p\u0159ipravit slo\u017eit\u00e9 tvary a velk\u00e9 rozm\u011bry keramiky z karbidu k\u0159em\u00edku. V z\u00e1vislosti na mechanismu slinov\u00e1n\u00ed lze tento druh slinut\u00e9ho karbidu k\u0159em\u00edku d\u00e1le rozd\u011blit na slinov\u00e1n\u00ed v pevn\u00e9 f\u00e1zi a slinov\u00e1n\u00ed v kapaln\u00e9 f\u00e1zi. \u03b2-SiC obsahuj\u00edc\u00ed stopov\u00e9 mno\u017estv\u00ed SiO lze slinovat za atmosf\u00e9rick\u00e9ho tlaku p\u0159id\u00e1n\u00edm B a C. Tato metoda v\u00fdrazn\u011b zlep\u0161uje kinetiku slinov\u00e1n\u00ed karbidu k\u0159em\u00edku. Po p\u0159id\u00e1n\u00ed vhodn\u00e9ho mno\u017estv\u00ed B se B b\u011bhem sp\u00e9k\u00e1n\u00ed nach\u00e1z\u00ed na hranic\u00edch zrn SiC a \u010d\u00e1ste\u010dn\u011b tvo\u0159\u00ed s SiC pevn\u00fd roztok, \u010d\u00edm\u017e se sni\u017euje energie na hranic\u00edch zrn SiC. Dopov\u00e1n\u00ed m\u00edrn\u00e9ho mno\u017estv\u00ed voln\u00e9ho C je pro sp\u00e9k\u00e1n\u00ed v pevn\u00e9 f\u00e1zi v\u00fdhodn\u00e9, proto\u017ee povrch SiC je obvykle oxidov\u00e1n mal\u00fdm mno\u017estv\u00edm generovan\u00e9ho SiO a p\u0159\u00eddavek m\u00edrn\u00e9ho mno\u017estv\u00ed C napom\u00e1h\u00e1 tomu, \u017ee se film SiO na povrchu SiC redukuje a odstra\u0148uje, \u010d\u00edm\u017e se zvy\u0161uje povrchov\u00e1 energie. Sp\u00e9k\u00e1n\u00ed v kapaln\u00e9 f\u00e1zi v\u0161ak bude m\u00edt negativn\u00ed \u00fa\u010dinek, proto\u017ee C bude reagovat s oxidov\u00fdmi p\u0159\u00edsadami za vzniku plynu, vzniku velk\u00e9ho mno\u017estv\u00ed otvor\u016f v keramick\u00e9m sp\u00e9kac\u00edm t\u011blese, co\u017e ovlivn\u00ed proces zhu\u0161\u0165ov\u00e1n\u00ed. \u010cistota, jemnost a f\u00e1zov\u00e9 slo\u017een\u00ed suroviny jsou v procesu slinov\u00e1n\u00ed karbidu k\u0159em\u00edku velmi d\u016fle\u017eit\u00e9. s. Proehazka slinoval slinut\u00fd karbid k\u0159em\u00edku s hustotou vy\u0161\u0161\u00ed ne\u017e 98% p\u0159i 2020 \u00b0C za atmosf\u00e9rick\u00e9ho tlaku sou\u010dasn\u00fdm p\u0159id\u00e1n\u00edm vhodn\u00e9ho mno\u017estv\u00ed B a C k ultrajemn\u00fdm pr\u00e1\u0161k\u016fm \u03b2-SiC (obsahuj\u00edc\u00edm m\u00e9n\u011b ne\u017e 2% kysl\u00edku). Syst\u00e9m SiC-B-C v\u0161ak pat\u0159\u00ed do kategorie slinov\u00e1n\u00ed v pevn\u00e9 f\u00e1zi, kter\u00e9 vy\u017eaduje vysokou teplotu slinov\u00e1n\u00ed a n\u00edzkou lomovou hou\u017eevnatost, lomov\u00fd zp\u016fsob je typick\u00fd pr\u016fchoz\u00ed lom, hrub\u00e1 zrna a \u0161patn\u00e1 rovnom\u011brnost. Zahrani\u010dn\u00ed v\u00fdzkum SiC se soust\u0159e\u010fuje p\u0159edev\u0161\u00edm na sp\u00e9k\u00e1n\u00ed v kapaln\u00e9 f\u00e1zi, tj. ur\u010dit\u00fd po\u010det sp\u00e9kac\u00edch p\u0159\u00edsad, p\u0159i ni\u017e\u0161\u00ed teplot\u011b, aby se dos\u00e1hlo zhutn\u011bn\u00ed SiC. Sp\u00e9k\u00e1n\u00ed SiC v kapaln\u00e9 f\u00e1zi nejen sni\u017euje teplotu sp\u00e9k\u00e1n\u00ed oproti sp\u00e9k\u00e1n\u00ed v pevn\u00e9 f\u00e1zi, ale tak\u00e9 zlep\u0161uje mikrostrukturu, a t\u00edm se zlep\u0161uj\u00ed vlastnosti sp\u00e9kan\u00e9ho t\u011blesa ve srovn\u00e1n\u00ed s vlastnostmi t\u011blesa sp\u00e9kan\u00e9ho v pevn\u00e9 f\u00e1zi.
\nM. Omori a kol. pou\u017eili oxidy vz\u00e1cn\u00fdch zemin ve sm\u011bsi s AlO nebo boridy k hust\u00e9mu slinov\u00e1n\u00ed SiC. Suzuki naproti tomu sp\u00e9kal SiC pouze s AlO jako p\u0159\u00edsadou p\u0159i teplot\u011b p\u0159ibli\u017en\u011b 2000 \u00b0C. A. Mulla a kol. sp\u00e9kali 0,5 \u03bcm \u03b2-SiC (s mal\u00fdm mno\u017estv\u00edm SiO na povrchu \u010d\u00e1stic) s AlO a YO jako p\u0159\u00edsadami p\u0159i ,1850-1950 \u00b0C a z\u00edskali relativn\u00ed hustotu keramiky SiC, kter\u00e1 byla v\u011bt\u0161\u00ed ne\u017e 95% teoretick\u00e9 hustoty, a zrna byla jemn\u00e1, s pr\u016fm\u011brnou velikost\u00ed 1,5 \u03bcm.
\nBylo zji\u0161t\u011bno, \u017ee mikrostruktura keramiky z karbidu k\u0159em\u00edku m\u00e1 hrub\u00e1 zrna a ty\u010dinkovitou strukturu s dobrou lomovou hou\u017eevnatost\u00ed. Ty\u010dinkovit\u00e1 zrna zvy\u0161uj\u00ed lomovou hou\u017eevnatost a z\u00e1rove\u0148 sni\u017euj\u00ed pevnost keramiky z karbidu k\u0159em\u00edku. Za \u00fa\u010delem dosa\u017een\u00ed lep\u0161\u00ed pevnosti a hou\u017eevnatosti p\u0159i sou\u010dasn\u00e9m sn\u00ed\u017een\u00ed teploty slinov\u00e1n\u00ed bylo u\u010din\u011bno mnoho pokus\u016f o zlep\u0161en\u00ed vlastnost\u00ed tohoto slinut\u00e9ho karbidu k\u0159em\u00edku \u00fapravou slo\u017een\u00ed skeln\u00e9 f\u00e1ze pomoc\u00ed r\u016fzn\u00fdch p\u0159\u00edsad. B\u011bhem procesu sp\u00e9k\u00e1n\u00ed vedlo zaveden\u00ed kapaln\u00e9 f\u00e1ze na hranici zrn a jedine\u010dn\u00e9 mezif\u00e1zov\u00e9 struktury k oslaben\u00ed mezif\u00e1zov\u00e9 struktury a lom materi\u00e1lu se zm\u011bnil na \u00fapln\u00fd pod\u00e9ln\u00fd lomov\u00fd re\u017eim, co\u017e vedlo k v\u00fdrazn\u00e9mu zv\u00fd\u0161en\u00ed pevnosti a hou\u017eevnatosti materi\u00e1lu. Av\u0161ak vzhledem k tomu, \u017ee p\u0159i pou\u017eit\u00ed p\u0159\u00edsady AlO vznik\u00e1 sklovit\u00e1 f\u00e1ze s n\u00edzk\u00fdm bodem t\u00e1n\u00ed a vysokou t\u011bkavost\u00ed, kter\u00e1 p\u0159i vy\u0161\u0161\u00edch teplot\u00e1ch podl\u00e9h\u00e1 siln\u00e9mu odpa\u0159ov\u00e1n\u00ed, co\u017e zp\u016fsobuje \u00fabytek hmotnosti materi\u00e1lu a nep\u0159\u00edzniv\u011b ovliv\u0148uje hutn\u011bn\u00ed materi\u00e1lu, je t\u0159eba hmotnostn\u00ed pod\u00edl AlO v p\u0159\u00edsad\u011b vhodn\u011b zv\u00fd\u0161it.<\/p>","protected":false},"excerpt":{"rendered":"
Pressureless sintered silicon carbide is considered to be the most promising sintered silicon carbide, and complex shapes and large sizes of silicon carbide ceramics can be prepared by the pressureless sintering process. Depending on the sintering mechanism, this kind of sintered silicon carbide can be further divided into solid-phase sintering and liquid-phase sintering. \u03b2-SiC containing […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"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\/cs\/wp-json\/wp\/v2\/posts\/578","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/siliconcarbide.net\/cs\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/siliconcarbide.net\/cs\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/siliconcarbide.net\/cs\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/siliconcarbide.net\/cs\/wp-json\/wp\/v2\/comments?post=578"}],"version-history":[{"count":1,"href":"https:\/\/siliconcarbide.net\/cs\/wp-json\/wp\/v2\/posts\/578\/revisions"}],"predecessor-version":[{"id":579,"href":"https:\/\/siliconcarbide.net\/cs\/wp-json\/wp\/v2\/posts\/578\/revisions\/579"}],"wp:attachment":[{"href":"https:\/\/siliconcarbide.net\/cs\/wp-json\/wp\/v2\/media?parent=578"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/siliconcarbide.net\/cs\/wp-json\/wp\/v2\/categories?post=578"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/siliconcarbide.net\/cs\/wp-json\/wp\/v2\/tags?post=578"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}