{"id":701,"date":"2026-11-07T11:48:10","date_gmt":"2026-11-07T03:48:10","guid":{"rendered":"https:\/\/ceramicatijolart.com\/?p=701"},"modified":"2026-11-07T11:48:10","modified_gmt":"2026-11-07T03:48:10","slug":"preco-dochadza-k-praskaniu-karbidu-kremika-spojeneho-nitridom-v-cyklickych-peciach","status":"publish","type":"post","link":"https:\/\/ceramicatijolart.com\/sk\/why-nitride-bonded-silicon-carbide-cracks-in-cyclic-kilns\/","title":{"rendered":"Pre\u010do doch\u00e1dza k praskaniu karbidu krem\u00edka spojen\u00e9ho nitridom v cyklick\u00fdch peciach"},"content":{"rendered":"

Pre\u010do doch\u00e1dza k praskaniu karbidu krem\u00edka spojen\u00e9ho nitridom v cyklick\u00fdch peciach, aj ke\u010f sa hodnoty pevnosti javia ako vysok\u00e9<\/strong><\/h1>\n

Dvan\u00e1s\u0165 rokov som pracoval s karbidom krem\u00edka spojen\u00fdm nitridom krem\u00edka pri v\u00fdrobe pecn\u00e9ho pr\u00edslu\u0161enstva a vysokoteplotn\u00fdch up\u00ednac\u00edch prvkov, a poruchy, ktor\u00e9 sa objavuj\u00fa naj\u010dastej\u0161ie, nie s\u00fa sp\u00f4soben\u00e9 jednoduch\u00fdm pre\u0165a\u017een\u00edm. Vznikaj\u00fa v d\u00f4sledku opakovan\u00fdch teplotn\u00fdch cyklov, ktor\u00e9 sp\u00f4sobuj\u00fa oxida\u010dn\u00e9 po\u0161kodenie v nitridovej spojovacej f\u00e1ze. Tento materi\u00e1l m\u00e1 spo\u010diatku dobr\u00fa pevnos\u0165 pri izbovej teplote a slu\u0161n\u00fa odolnos\u0165 vo\u010di tepeln\u00fdm \u0161okom, ale po dostato\u010dnom po\u010dte cyklov zahrievania a ochladzovania na vzduchu sa nitrid krem\u00edka, ktor\u00fd sp\u00e1ja zrn\u00e1 karbidu krem\u00edka, za\u010dne oxidova\u0165. T\u00e1to oxid\u00e1cia sp\u00f4sobuje objemov\u00fa expanziu a vznik mikrotrhl\u00edn, ktor\u00e9 sa nakoniec prepoja.<\/p>\n

Karbid krem\u00edka spojen\u00fd nitridom zvy\u010dajne obsahuje sie\u0165 nitridu krem\u00edka, ktor\u00e1 vznik\u00e1 po\u010das nitridovacieho vypa\u013eovania. T\u00e1to v\u00e4zba dod\u00e1va telu vy\u0161\u0161iu pevnos\u0165 a lep\u0161iu odolnos\u0165 vo\u010di tepeln\u00fdm \u0161okom v porovnan\u00ed s mnoh\u00fdmi druhmi karbidu krem\u00edka spojen\u00e9ho \u00edlom alebo oxidom. Obmedzenie sa prejavuje vtedy, ke\u010f teplota v oxida\u010dnej atmosf\u00e9re pravidelne prekra\u010duje pribli\u017ene 1400 \u00b0C. Nitrid krem\u00edka sa oxiduje na oxid kremi\u010dit\u00fd a s t\u00fdm spojen\u00e1 expanzia vyvol\u00e1va nap\u00e4tie v \u0161trukt\u00fare. Pri nepretr\u017eitom prev\u00e1dzkovan\u00ed pri vysok\u00fdch teplot\u00e1ch sa po\u0161kodenie pomaly hromad\u00ed. V peciach, ktor\u00e9 pracuj\u00fa denne alebo nieko\u013ekokr\u00e1t t\u00fd\u017edenne, sa prejavuje ove\u013ea r\u00fdchlej\u0161ie.<\/p>\n

Laborat\u00f3rne \u00fadaje zo sk\u00fa\u0161ok oxid\u00e1cie a cyklick\u00fdch sk\u00fa\u0161ok<\/strong><\/p>\n

Ty\u010de zo \u0161tandardnej zliatiny karbidu krem\u00edka s nitridovou v\u00e4zbou sme podrobili kombinovanej sk\u00fa\u0161ke oxid\u00e1cie a teplotn\u00fdch cyklov. Vzorky boli 50 hod\u00edn vystaven\u00e9 teplote 1450 \u00b0C na vzduchu, potom pre\u0161li desa\u0165kr\u00e1t cyklom medzi teplotami 1450 \u00b0C a 200 \u00b0C. Pevnos\u0165 v ohybe pri izbovej teplote sa p\u00f4vodne pohybovala v rozmedz\u00ed pribli\u017ene 180\u2013200 MPa. Po ukon\u010den\u00ed cel\u00e9ho testu klesla na 110\u2013130 MPa. Priemern\u00fd n\u00e1rast hmotnosti bol 1,5\u20132,0 % a prie\u010dne rezy odhalili vrstvu bohat\u00fa na oxid kremi\u010dit\u00fd s hr\u00fabkou 100\u2013150 \u00b5m, v ktorej sa nach\u00e1dzali jemn\u00e9 trhliny siahaj\u00face od povrchu do oblast\u00ed s nitridovou v\u00e4zbou. Paraleln\u00e1 s\u00e9ria vzoriek, ktor\u00e9 boli udr\u017eiavan\u00e9 pri rovnakej teplote, ale bez cyklov ochladzovania, stratila menej pevnosti \u2013 pribli\u017ene 20 % namiesto 35\u201340 %. Cyklovanie zrete\u013ene ur\u00fdchlilo po\u0161kodenie, akon\u00e1hle sa za\u010dala oxid\u00e1cia.<\/p>\n

Pr\u00edpad z praxe z keramickej pece<\/strong><\/p>\n

Z\u00e1vod na v\u00fdrobu sanit\u00e1rnej keramiky pou\u017e\u00edval nosn\u00edky a st\u013apiky z karbidu krem\u00edka spojen\u00e9 nitridom v \u0161uttlovom peci, kde sa vypa\u013eovalo pri teplote 1420\u20131440 \u00b0C. Vzh\u013eadom na v\u00fdrobn\u00fd harmonogram sa pec medzi v\u00e4\u010d\u0161inou vkladov ochladzovala takmer na teplotu okolia. Po pribli\u017ene \u00f4smich mesiacoch sa na viacer\u00fdch nosn\u00edkoch objavili pozd\u013a\u017ene trhliny a museli by\u0165 vymenen\u00e9. Identick\u00e9 nosn\u00edky v tunelovej peci s nepretr\u017eit\u00fdm prev\u00e1dzkou pri rovnakej maxim\u00e1lnej teplote boli st\u00e1le v prev\u00e1dzke aj po viac ako dvoch rokoch. Rozrezali sme prasknut\u00fd nosn\u00edk z voz\u00edkov\u00e9 pece a zistili sme t\u00fa ist\u00fa oxidovan\u00fa viazaciu f\u00e1zu a povrchov\u00e9 praskliny, ak\u00e9 sme namerali v laborat\u00f3riu. \u0160pi\u010dkov\u00e1 teplota a atmosf\u00e9ra boli porovnate\u013en\u00e9; rozdielom bol po\u010det \u00fapln\u00fdch tepeln\u00fdch cyklov. Ke\u010f z\u00e1vod obmedzil v\u00edkendov\u00e9 ochladzovanie a udr\u017eiaval pec medzi jednotliv\u00fdmi v\u00fdrobn\u00fdmi cyklami na teplote pribli\u017ene nad 300 \u00b0C, nov\u00e9 nosn\u00edky z rovnak\u00e9ho druhu karbidu krem\u00edka spojen\u00e9ho nitridom vydr\u017eali zrete\u013ene dlh\u0161ie. Materi\u00e1l sa nezmenil \u2013 zmenil sa prev\u00e1dzkov\u00fd cyklus.<\/p>\n

\u010co vlastne obmedzuje \u017eivotnos\u0165<\/strong><\/p>\n

Oxid\u00e1cia v\u00e4zby nitridu krem\u00edka je hlavn\u00fdm faktorom obmedzuj\u00facim \u017eivotnos\u0165 na vzduchu, ak teploty dlhodobo prekra\u010duj\u00fa pribli\u017ene 1400 \u00b0C. Tepeln\u00e9 cykly tento jav zhor\u0161uj\u00fa, preto\u017ee roz\u0165ahovanie a zmr\u0161\u0165ovanie vytv\u00e1raj\u00fa cesty pre v\u00e4\u010d\u0161\u00ed pr\u00edsun kysl\u00edka a menia mal\u00e9 oxidovan\u00e9 z\u00f3ny na trhliny. V reduk\u010dn\u00fdch atmosf\u00e9rach r\u00fdchlos\u0165 oxid\u00e1cie prudko kles\u00e1 a \u017eivotnos\u0165 je zvy\u010dajne dlh\u0161ia, \u010do je d\u00f4vodom, pre\u010do t\u00e1 ist\u00e1 trieda \u010dasto dosahuje lep\u0161ie v\u00fdsledky v ur\u010dit\u00fdch metalurgick\u00fdch aplik\u00e1ci\u00e1ch ako v keramick\u00fdch peciach vypa\u013eovan\u00fdch na vzduchu.<\/p>\n

D\u00f4le\u017eit\u00fa \u00falohu zohr\u00e1va aj hr\u00fabka steny a r\u00fdchlos\u0165 zmien teploty. V hrub\u0161\u00edch \u010dastiach vznikaj\u00fa po\u010das r\u00fdchleho ochladzovania v\u00e4\u010d\u0161ie teplotn\u00e9 gradienty, \u010do okrem po\u0161kodenia oxid\u00e1ciou sp\u00f4sobuje aj dodato\u010dn\u00e9 mechanick\u00e9 nam\u00e1hanie. Niektor\u00e9 prev\u00e1dzky akceptuj\u00fa krat\u0161iu \u017eivotnos\u0165 v\u00fdmenou za vy\u0161\u0161iu pevnos\u0165 za tepla a tepeln\u00fa vodivos\u0165, ktor\u00fa poskytuje karbid krem\u00edka s nitridov\u00fdm spojivom v porovnan\u00ed s alternat\u00edvami s oxidov\u00fdm spojivom. In\u00ed prech\u00e1dzaj\u00fa na in\u00e9 triedy alebo menia program vypa\u013eovania, akon\u00e1hle sa praskliny za\u010dn\u00fa vyskytova\u0165 \u010dastej\u0161ie.<\/p>\n

Ak doch\u00e1dza k praskaniu pecn\u00fdch v\u00fdstuh alebo pr\u00edslu\u0161enstva z karbidu krem\u00edka spojen\u00e9ho nitridom e\u0161te sk\u00f4r, ne\u017e by to bolo mo\u017en\u00e9 vysvetli\u0165 abraz\u00edvnym opotreben\u00edm alebo jednoduch\u00fdm pre\u0165a\u017een\u00edm, zvy\u010dajne je potrebn\u00e9 h\u013eada\u0165 pr\u00ed\u010dinu v kombin\u00e1cii \u0161pi\u010dkovej teploty, oxida\u010dnej atmosf\u00e9ry a po\u010dtu tepeln\u00fdch cyklov. \u00dadaje o po\u010diato\u010dnej pevnosti s\u00fa re\u00e1lne, ale nezost\u00e1vaj\u00fa kon\u0161tantn\u00e9, ke\u010f sa nitridov\u00e1 v\u00e4zba za\u010dne oxidova\u0165 v d\u00f4sledku opakovan\u00e9ho zahrievania a ochladzovania.<\/p>","protected":false},"excerpt":{"rendered":"

Why Nitride Bonded Silicon Carbide Cracks in Cyclic Kilns Even When Strength Numbers Look High I\u2019ve spent twelve years working with silicon nitride bonded silicon carbide in kiln furniture and high-temperature fixtures, and the failures that show up most often aren\u2019t from simple overload. They come from repeated thermal cycling that opens up oxidation damage […]<\/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":"default","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":"default","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"set","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-701","post","type-post","status-publish","format-standard","hentry","category-knowledge"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/posts\/701","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/comments?post=701"}],"version-history":[{"count":1,"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/posts\/701\/revisions"}],"predecessor-version":[{"id":702,"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/posts\/701\/revisions\/702"}],"wp:attachment":[{"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/media?parent=701"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/categories?post=701"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ceramicatijolart.com\/sk\/wp-json\/wp\/v2\/tags?post=701"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}