{"id":716,"date":"2026-10-11T21:20:22","date_gmt":"2026-10-11T13:20:22","guid":{"rendered":"https:\/\/siliconcarbide.net\/?p=716"},"modified":"2026-10-11T21:20:22","modified_gmt":"2026-10-11T13:20:22","slug":"proc-karbid-kremiku-spojeny-nitridem-ztraci-pevnost-po-8-az-12-mesicich","status":"publish","type":"post","link":"https:\/\/siliconcarbide.net\/cs\/why-nitride-bonded-silicon-carbide-lose-strength-after-8-12-months\/","title":{"rendered":"Pro\u010d karbid k\u0159em\u00edku spojen\u00fd nitridem ztr\u00e1c\u00ed pevnost po 8\u201312 m\u011bs\u00edc\u00edch"},"content":{"rendered":"<h1 dir=\"auto\"><strong>Pro\u010d karbid k\u0159em\u00edku spojen\u00fd nitridem ztr\u00e1c\u00ed pevnost po 8\u201312 m\u011bs\u00edc\u00edch v oxida\u010dn\u00edm prost\u0159ed\u00ed<\/strong><\/h1>\n<p dir=\"auto\">Dvan\u00e1ct let jsem se zab\u00fdval za\u0159\u00edzen\u00edm pro vysok\u00e9 teploty v \u0160anghaji a okoln\u00edch keramick\u00fdch a hutn\u00edch z\u00e1vodech. Jedn\u00edm z nej\u010dast\u011bj\u0161\u00edch probl\u00e9m\u016f, se kter\u00fdmi se u karbidu k\u0159em\u00edku s nitridovou vazbou setk\u00e1v\u00e1m, je to, \u017ee police, desky a nosi\u010de v peci vypadaj\u00ed p\u0159i vlo\u017een\u00ed do pece pevn\u011b, av\u0161ak po n\u011bkolika m\u011bs\u00edc\u00edch b\u011b\u017en\u00e9ho provozu za\u010dnou praskat nebo se proh\u00fdbat pod zat\u00ed\u017een\u00edm, kter\u00e9 d\u0159\u00edve bez probl\u00e9m\u016f zvl\u00e1daly. V\u011bt\u0161ina obsluhy p\u0159edpokl\u00e1d\u00e1, \u017ee se materi\u00e1l prost\u011b \u201copot\u0159eboval\u201d nebo \u017ee byl vypalovac\u00ed cyklus p\u0159\u00edli\u0161 agresivn\u00ed. V link\u00e1ch, se kter\u00fdmi pracuji, je skute\u010dnou p\u0159\u00ed\u010dinou postupn\u00e1 oxidace nitridov\u00e9 pojivov\u00e9 f\u00e1ze, jakmile je povrch vystaven vzduchu p\u0159i vysok\u00e9 teplot\u011b.<\/p>\n<p dir=\"auto\">U karbidu k\u0159em\u00edku spojen\u00e9ho nitridem zaji\u0161\u0165uje matrice z nitridu k\u0159em\u00edku soudr\u017enost zrn karbidu k\u0159em\u00edku a dod\u00e1v\u00e1 d\u00edlu pevnost a odolnost proti tepeln\u00fdm \u0161ok\u016fm. V reduk\u010dn\u00ed nebo neutr\u00e1ln\u00ed atmosf\u00e9\u0159e z\u016fst\u00e1v\u00e1 tato vazba relativn\u011b stabiln\u00ed. Jakmile v\u0161ak pec pracuje s p\u0159ebytkem vzduchu \u2013 co\u017e je b\u011b\u017en\u00e9 p\u0159i p\u0159eru\u0161ovan\u00e9m vypalov\u00e1n\u00ed keramiky nebo p\u0159i ur\u010dit\u00fdch cyklech tepeln\u00e9ho zpracov\u00e1n\u00ed kov\u016f \u2013 kysl\u00edk napad\u00e1 nitrid. Na povrchu a, co je d\u016fle\u017eit\u011bj\u0161\u00ed, na hranic\u00edch zrn se tvo\u0159\u00ed tenk\u00e1 vrstva bohat\u00e1 na oxid k\u0159emi\u010dit\u00fd. D\u00edl se nezni\u010d\u00ed n\u00e1hle; postupn\u011b ztr\u00e1c\u00ed pevnost v ohybu a st\u00e1v\u00e1 se citliv\u011bj\u0161\u00edm na teplotn\u00ed gradienty. Pravideln\u011b se setk\u00e1v\u00e1m s deskami, jejich\u017e pevnost byla v nov\u00e9m stavu v\u00fdrazn\u011b nad 40 MPa, ale po 8\u201312 m\u011bs\u00edc\u00edch ka\u017edodenn\u00edho cyklu mezi 1200 \u00b0C a pokojovou teplotou klesla na hodnoty v n\u00edzk\u00fdch 20 MPa.<\/p>\n<p dir=\"auto\">Praktick\u00fd d\u016fsledek se projevuje dv\u011bma zp\u016fsoby. Zaprv\u00e9 se na polic\u00edch objevuj\u00ed vlasov\u00e9 trhliny, kter\u00e9 vznikaj\u00ed na okraj\u00edch nebo v okol\u00ed op\u011brn\u00fdch bod\u016f a pot\u00e9 se \u0161\u00ed\u0159\u00ed pod vlivem vlastn\u00ed hmotnosti polic a zat\u00ed\u017een\u00ed zbo\u017e\u00edm. Zadruh\u00e9 doch\u00e1z\u00ed ke sn\u00ed\u017een\u00ed efektivn\u00ed nosnosti je\u0161t\u011b p\u0159edt\u00edm, ne\u017e se objev\u00ed viditeln\u00e9 trhliny, tak\u017ee obsluha bu\u010f sn\u00ed\u017e\u00ed po\u010det kus\u016f na polici, nebo akceptuje vy\u0161\u0161\u00ed m\u00edru rozbit\u00ed. V obou p\u0159\u00edpadech mus\u00ed z\u00e1vod nakonec vym\u011bnit reg\u00e1ly d\u0159\u00edve, ne\u017e p\u0159edpokl\u00e1dal p\u016fvodn\u00ed n\u00e1kupn\u00ed kalkul. Z\u00e1vody provozuj\u00edc\u00ed kontinu\u00e1ln\u00ed posunova\u010de nebo v\u00e1le\u010dkov\u00e9 pece s p\u0159\u00edsn\u011bj\u0161\u00ed regulac\u00ed atmosf\u00e9ry obvykle dosahuj\u00ed del\u0161\u00ed \u017eivotnosti u stejn\u00e9 t\u0159\u00eddy v\u00fdrobk\u016f; u p\u0159eru\u0161ovan\u00fdch \u0161ar\u017eov\u00fdch pec\u00ed, b\u011b\u017en\u00fdch v oblasti \u0160anghaje, se tento probl\u00e9m projev\u00ed rychleji, proto\u017ee p\u0159i ka\u017ed\u00e9m ochlazen\u00ed se na hork\u00e9 povrchy dost\u00e1v\u00e1 \u010derstv\u00fd vzduch.<\/p>\n<p dir=\"auto\">Jakmile za\u010dnete pova\u017eovat f\u00e1zi spojen\u00ed za omezuj\u00edc\u00ed faktor, je zcela jasn\u00e9, co ve skute\u010dnosti zpomaluje degradaci. Udr\u017eujte maxim\u00e1ln\u00ed teplotu a dobu v\u00fddr\u017ee na t\u00e9to teplot\u011b na nejni\u017e\u0161\u00ed \u00farovni, jakou proces dovoluje; ka\u017ed\u00fdch dal\u0161\u00edch 50 \u00b0C nad 1350 \u00b0C znateln\u011b zrychluje rychlost oxidace, kterou m\u011b\u0159\u00edm na vr\u00e1cen\u00fdch d\u00edlech. Pokud to konstrukce pece umo\u017e\u0148uje, kr\u00e1tk\u00e9 propl\u00e1chnut\u00ed nebo m\u00edrn\u011b reduk\u010dn\u00ed atmosf\u00e9ra b\u011bhem v\u00fddr\u017ee p\u0159i vysok\u00e9 teplot\u011b sn\u00ed\u017e\u00ed parci\u00e1ln\u00ed tlak kysl\u00edku natolik, \u017ee se \u017eivotnost prodlou\u017e\u00ed o n\u011bkolik m\u011bs\u00edc\u016f. Stejn\u011b d\u016fle\u017eit\u00e9 je mechanick\u00e9 zat\u00ed\u017een\u00ed. Nitridov\u011b spojen\u00e9 SiC, kter\u00e9 jsou podep\u0159eny pouze na konc\u00edch a nesou t\u011b\u017ek\u00e1, nerovnom\u011brn\u00e1 pracovn\u00ed zat\u00ed\u017een\u00ed, vyv\u00edjej\u00ed na spodn\u00ed plo\u0161e vy\u0161\u0161\u00ed tahov\u00e1 nap\u011bt\u00ed; jakmile je povrch oslaben oxidac\u00ed, tato nap\u011bt\u00ed zp\u016fsobuj\u00ed d\u0159\u00edv\u011bj\u0161\u00ed vznik trhlin. P\u0159echod na t\u0159\u00edbodovou nebo pr\u016fb\u011b\u017enou oporu, p\u0159\u00edpadn\u011b pouh\u00e9 sn\u00ed\u017een\u00ed maxim\u00e1ln\u00edho zat\u00ed\u017een\u00ed na desku o 15\u201320 %, \u010dasto obnov\u00ed p\u016fvodn\u00ed interval v\u00fdm\u011bny bez zm\u011bny t\u0159\u00eddy materi\u00e1lu.<\/p>\n<p dir=\"auto\">U vr\u00e1cen\u00fdch desek tak\u00e9 kontroluji tlou\u0161\u0165ku oxidovan\u00e9 vrstvy. Norm\u00e1ln\u00ed je rovnom\u011brn\u00fd sv\u011btle \u0161ed\u00fd povrchov\u00fd film o tlou\u0161\u0165ce n\u011bkolika set mikron\u016f; m\u00edsty siln\u011bj\u0161\u00ed okuj\u00ed nebo pr\u00e1\u0161kov\u00e1n\u00ed na okraj\u00edch obvykle znamen\u00e1 bu\u010f hork\u00e9 m\u00edsto v peci, nebo dlouhodob\u00e9 vystaven\u00ed teplot\u00e1m nad doporu\u010den\u00fdm limitem. Z\u00e1vody, kter\u00e9 zaznamen\u00e1vaj\u00ed hodnoty atmosf\u00e9ry a maxim\u00e1ln\u00ed zat\u00ed\u017een\u00ed polic spolu s po\u010dtem cykl\u016f p\u0159ed v\u00fdskytem prvn\u00edch trhlin, mohou obvykle prodlou\u017eit pr\u016fm\u011brnou \u017eivotnost stejn\u00e9ho SiC s nitridov\u00fdm pojivem z p\u0159ibli\u017en\u011b 10 m\u011bs\u00edc\u016f na 14\u201316 m\u011bs\u00edc\u016f. Z\u00e1vody, kter\u00e9 nad\u00e1le pou\u017e\u00edvaj\u00ed p\u016fvodn\u00ed hust\u00fd vzorec osazen\u00ed a atmosf\u00e9ru s pln\u00fdm p\u0159\u00edvodem vzduchu, prost\u011b vym\u011b\u0148uj\u00ed desky v krat\u0161\u00edch, n\u00e1kladn\u011bj\u0161\u00edch intervalech a neust\u00e1le se div\u00ed, pro\u010d nov\u00e1 sada nevydr\u017e\u00ed d\u00e9le ne\u017e ta p\u0159edchoz\u00ed.<\/p>\n<p dir=\"auto\">Samotn\u00fd materi\u00e1l m\u00e1 dlouhou \u017eivotnost, pokud je chr\u00e1n\u011bna vazebn\u00e1 f\u00e1ze. Rozd\u00edl, kter\u00fd v praxi pozoruji, t\u00e9m\u011b\u0159 nikdy nespo\u010d\u00edv\u00e1 v n\u00e1hl\u00e9 zm\u011bn\u011b kvality suroviny; jde sp\u00ed\u0161e o to, zda z\u00e1vod pova\u017euje oxidaci a zat\u00ed\u017een\u00ed za prom\u011bnn\u00e9, kter\u00e9 lze regulovat, nebo za nevyhnuteln\u00e9 r\u00e1mcov\u00e9 podm\u00ednky.<\/p>","protected":false},"excerpt":{"rendered":"<p>Why Nitride Bonded Silicon Carbide Lose Strength After 8\u201312 Months in Oxidizing Atmospheres I\u2019ve spent twelve years dealing with high-temperature equipment around Shanghai and the surrounding ceramics and metallurgy plants. One of the most consistent problems I see with nitride bonded silicon carbide is that the kiln shelves, plates, and setters look solid when they&hellip;&nbsp;<\/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":"off","neve_meta_content_width":70,"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-716","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\/716","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=716"}],"version-history":[{"count":1,"href":"https:\/\/siliconcarbide.net\/cs\/wp-json\/wp\/v2\/posts\/716\/revisions"}],"predecessor-version":[{"id":717,"href":"https:\/\/siliconcarbide.net\/cs\/wp-json\/wp\/v2\/posts\/716\/revisions\/717"}],"wp:attachment":[{"href":"https:\/\/siliconcarbide.net\/cs\/wp-json\/wp\/v2\/media?parent=716"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/siliconcarbide.net\/cs\/wp-json\/wp\/v2\/categories?post=716"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/siliconcarbide.net\/cs\/wp-json\/wp\/v2\/tags?post=716"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}