Spekanie keramiky z karbidu krem\u00edka, ktor\u00e1 obsahuje prvky C a B4C ako spekanie podporn\u00e9 l\u00e1tky, je spekanie v tuhej f\u00e1ze a proces spekania je riaden\u00fd najm\u00e4 dif\u00faznym mechanizmom, pri\u010dom optim\u00e1lna teplota spekania je 2150 \u00b0C. Proces spekania je jednoduch\u00fd a \u013eahko kontrolovate\u013en\u00fd. Pridanie vhodn\u00e9ho obsahu C + B4C spek\u00e1rskych pr\u00edsad spekan\u00e9ho karbidu krem\u00edka Proces spekania je jednoduch\u00fd a \u013eahko kontrolovate\u013en\u00fd, spekanie keramiky v porovnan\u00ed s polotovarom m\u00e1 pribli\u017ene 30% objemov\u00e9ho zmr\u0161tenia, m\u00f4\u017eete z\u00edska\u0165 vy\u0161\u0161iu hustotu, mechanick\u00e9 vlastnosti \u0161peci\u00e1lnej keramiky z karbidu krem\u00edka. V s\u00fa\u010dasnosti sa be\u017ene pou\u017e\u00edvaj\u00fa spek\u00e1rske pr\u00edsady B4C + C, BN + C, BP (fosfid b\u00f3ru) + C, AI + C, AIN + C at\u010f. Pridan\u00edm vhodn\u00e9ho obsahu C + B4C SiC do beztlakov\u00e9ho spekania je proces pre tento druh spekan\u00e9ho siku jednoduch\u00fd, \u013eahko kontrolovate\u013en\u00fd, hustota materi\u00e1lu je vy\u0161\u0161ia, maxim\u00e1lna hustota 3,169\/cm3 (relat\u00edvna hustota 98,75%); mechanick\u00e9 vlastnosti s\u00fa lep\u0161ie, maxim\u00e1lna pevnos\u0165 v tlaku 550 MPa.
\n Surovina karbidu krem\u00edka m\u00e1 prednostne hodnotu D50 0,5 - 0,8 mikr\u00f3nu v podobe jednoduch\u00e9ho mikropr\u00e1\u0161ku. Zvy\u010dajne ide o chemicky upraven\u00fd zelen\u00fd karbid krem\u00edka s mikrometrami so \u0161pecifick\u00fdm povrchom 20 m3\/g. A obsah kysl\u00edka by mal by\u0165 \u010do najni\u017e\u0161\u00ed; okrem toho by sa malo zvoli\u0165 mno\u017estvo pridan\u00e9ho B pribli\u017ene 0,5% - 1,5%, zatia\u013e \u010do mno\u017estvo pridan\u00e9ho C z\u00e1vis\u00ed od \u00farovne obsahu kysl\u00edka v SiC pr\u00e1\u0161ku. Chemick\u00e9 zlo\u017eenie SIC>99%, F-C<0,1, Si+SiO2<0,1, Fe2O3<0,08. Tvar a ve\u013ekostn\u00e9 zlo\u017eenie \u010dast\u00edc, tvar \u010dast\u00edc je takmer gu\u013eovit\u00fd, aby sa dosiahlo \u010do najkompaktnej\u0161ie stohovanie.
\n Pr\u00eddavok B4C a C patr\u00ed do kateg\u00f3rie spekania v pevnej f\u00e1ze, ktor\u00e9 si vy\u017eaduje vy\u0161\u0161ie teploty spekania.Hnacou silou spekania SiC je: rozdiel medzi povrchovou energiou \u010dast\u00edc pr\u00e1\u0161ku (Eb) a kmitav\u00fdm povrchom z\u0155n polykry\u0161talick\u00e9ho spekan\u00e9ho telesa (Es), \u010do vedie k zn\u00ed\u017eeniu vo\u013enej energie syst\u00e9mu. Dopovan\u00fd vhodn\u00fdm mno\u017estvom B4C sa B4C po\u010das spekania nach\u00e1dza na hranici z\u0155n SiC, pri\u010dom \u010diasto\u010dne tvor\u00ed pevn\u00fd roztok s SiC, \u010d\u00edm sa zni\u017euje kapacita hranice 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, \u010do vedie k tvorbe mal\u00e9ho mno\u017estva Si02, a pridanie mierneho mno\u017estva C pom\u00e1ha, aby sa redukcia filmu Si02 na povrchu SiC odstr\u00e1nila, \u010d\u00edm sa zvy\u0161uje povrchov\u00e1 energia Eb.
\n Syst\u00e9m SiC podlieha rozkladu a sublim\u00e1cii pri tlaku 1,013x105Pa a teplote vy\u0161\u0161ej ako 1880 \u00b0C. Syst\u00e9m SiC obsahuje plynn\u00e9 f\u00e1zy ako Si, Si2, Si3, C, C2, C3, C4, C5, SiC, Si2C, SiC2 at\u010f. a teplotn\u00fd rozdiel je z\u00e1kladn\u00fdm faktorom procesu sublim\u00e1cie po\u010das rastu kry\u0161t\u00e1lov SiC a cel\u00e9mu procesu dominuje transport hmoty. Tieto r\u00f4zne plynn\u00e9 f\u00e1zy v syst\u00e9me SiC sa dif\u00faziou zlu\u010duj\u00fa na matrici kry\u0161t\u00e1lu SiC, \u010do vedie k rastu \u010dast\u00edc kry\u0161t\u00e1lu SiC. V pr\u00edpade vzoriek syst\u00e9mu C+B4C s pomocn\u00fdm spekan\u00edm je po\u017eadovan\u00e1 teplota spekania vy\u0161\u0161ia z d\u00f4vodu preva\u017ene pevnof\u00e1zov\u00e9ho spekania a arg\u00f3n sa priv\u00e1dza ako ochrann\u00e1 atmosf\u00e9ra pri teplote pribli\u017ene 1300 \u00b0C, preto\u017ee arg\u00f3n je priazniv\u00fd na zn\u00ed\u017eenie rozkladu SiC pri vysok\u00fdch teplot\u00e1ch nad 1300 \u00b0C. Meranie kvality spekan\u00e9ho telesa SiC m\u00e1 dve nevyhnutn\u00e9 podmienky: n\u00edzka p\u00f3rovitos\u0165, \u010do najhustej\u0161ia; \u010do najmen\u0161ie zrno.<\/p>","protected":false},"excerpt":{"rendered":"
The sintering of silicon carbide ceramic containing C and B4C elements as sintering aids is solid-phase sintering, and the sintering process is mainly controlled by the diffusion mechanism, with an optimum sintering temperature of 2150\u00b0C. The sintering process is simple and easy to control. Add the appropriate content of C + B4C sintering additives […]<\/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-574","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\/574","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=574"}],"version-history":[{"count":3,"href":"https:\/\/siliconcarbide.net\/sk\/wp-json\/wp\/v2\/posts\/574\/revisions"}],"predecessor-version":[{"id":577,"href":"https:\/\/siliconcarbide.net\/sk\/wp-json\/wp\/v2\/posts\/574\/revisions\/577"}],"wp:attachment":[{"href":"https:\/\/siliconcarbide.net\/sk\/wp-json\/wp\/v2\/media?parent=574"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/siliconcarbide.net\/sk\/wp-json\/wp\/v2\/categories?post=574"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/siliconcarbide.net\/sk\/wp-json\/wp\/v2\/tags?post=574"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}