Lid\u00e9 naz\u00fdvaj\u00ed hexagon\u00e1ln\u00ed nitrid boru \u201eb\u00edl\u00fdm grafitem\u201c, proto\u017ee jeho krystalov\u00e1 struktura je zalo\u017eena na stejn\u00e9m principu: vrstven\u00fdch desk\u00e1ch, kter\u00e9 se vz\u00e1jemn\u011b posouvaj\u00ed. Proto se such\u00fd film z h-BN jev\u00ed jako kluzk\u00fd. Toto srovn\u00e1n\u00ed v\u0161ak p\u0159est\u00e1v\u00e1 platit, jakmile dojde k zah\u0159\u00e1t\u00ed, oxidaci nebo k p\u0159iveden\u00ed elektrick\u00e9ho nap\u011bt\u00ed. Grafit je vodi\u010d a na vzduchu za\u010d\u00edn\u00e1 oxidovat p\u0159i teplot\u011b kolem 500\u2013600 \u00b0C. Hexagon\u00e1ln\u00ed BN z\u016fst\u00e1v\u00e1 izolantem a na vzduchu pova\u017eujeme za praktickou mez oxidace teplotu 900\u20131000 \u00b0C. V dus\u00edku nebo ve vakuu je tato teplota mnohem vy\u0161\u0161\u00ed, a\u017e k 2000 \u00b0C a v\u00edce. To je d\u016fvod, pro\u010d vol\u00edme BN nam\u00edsto uhl\u00edku, kdy\u017e mus\u00ed povlak odolat vysok\u00fdm teplot\u00e1m a z\u016fstat dielektrick\u00fd.<\/p>\n
Pr\u00e1\u0161ek, kter\u00fd prod\u00e1v\u00e1me pro n\u00e1t\u011bry, je obvykle deskovit\u00fd h-BN, \u010dasto v rozmez\u00ed n\u011bkolika mikron\u016f, n\u011bkdy i jemn\u011bj\u0161\u00ed pro hladk\u00e9 n\u00e1st\u0159ikov\u00e1n\u00ed. Po sm\u00edch\u00e1n\u00ed s pojivem se z n\u011bj st\u00e1v\u00e1 odformovac\u00ed barva pro formy, lisovac\u00ed n\u00e1stroje, p\u00e1nve a trubky termo\u010dl\u00e1nk\u016f. U\u017eite\u010dn\u00fdm trikem p\u0159i pr\u00e1ci s roztaven\u00fdm hlin\u00edkem je sm\u00e1\u010den\u00ed. Hlin\u00edk ulp\u00edv\u00e1 na nitridu boru s vysok\u00fdm kontaktn\u00edm \u00fahlem \u2013 podle publikovan\u00fdch v\u00fdsledk\u016f test\u016f s vis\u00edc\u00ed kapkou se pohybuje v rozmez\u00ed od p\u0159ibli\u017en\u011b 160\u00b0 a\u017e do 900\u00b0C \u2013 tak\u017ee kov se neuchyt\u00ed na keramiku tak, jak se uchyt\u00ed na oxid hlinit\u00fd nebo na zne\u010di\u0161t\u011bnou ocelovou patku. Se\u0161kr\u00e1bn\u011bte, vylijte, set\u0159este zbytky. Grafit m\u016f\u017ee tak\u00e9 slou\u017eit jako uvol\u0148ovac\u00ed prost\u0159edek, dokud se nesp\u00e1l\u00ed a nezanech\u00e1 uhl\u00edkovou skvrnu nebo d\u016flek. BN zanech\u00e1v\u00e1 b\u00edl\u00fd film. D\u00edlny, kter\u00e9 potahuj\u00ed odtokov\u00e9 \u017elaby a ponorn\u00e9 trubky, si tento rozd\u00edl v\u0161imnou po t\u00fddnu, nikoli a\u017e po p\u0159edn\u00e1\u0161ce v laborato\u0159i.<\/p>\n
Tepeln\u00e1 vodivost je v monokrystalu slu\u0161n\u00e1 a siln\u011b anizotropn\u00ed. U d\u00edlu lisovan\u00e9ho za tepla nebo u povlaku se dostanete k pr\u016fm\u011brn\u011bj\u0161\u00ed hodnot\u011b, kter\u00e1 je v\u0161ak st\u00e1le dostate\u010dn\u011b vysok\u00e1 na to, aby se keramika z nitridu boru pou\u017e\u00edvala tam, kde se mus\u00ed \u0161\u00ed\u0159it teplo, ale proud nem\u016f\u017ee: rozvad\u011b\u010de tepla, povlaky pro stabilizaci teploty, vysokoteplotn\u00ed elektrick\u00e1 izolace. Tato kombinace \u2013 veden\u00ed tepla a blokov\u00e1n\u00ed proudu \u2013 nen\u00ed vlastnost\u00ed grafitu. Grafit se chov\u00e1 v obou p\u0159\u00edpadech opa\u010dn\u011b, ne\u017e by se od izolantu o\u010dek\u00e1valo.<\/p>\n
Kubick\u00fd BN je zcela odli\u0161n\u00fd materi\u00e1l. Stejn\u00e9 prvky, m\u0159\u00ed\u017eka podobn\u00e1 diamantu, tvrdost jako u \u0159ezn\u00e9ho n\u00e1stroje. Neobjedn\u00e1vejte si c-BN, pokud m\u00e1te na mysli uvol\u0148ovac\u00ed povlak, a neo\u010dek\u00e1vejte, \u017ee pr\u00e1\u0161ek h-BN ur\u010den\u00fd pro lakov\u00e1n\u00ed bude vhodn\u00fd k obr\u00e1b\u011bn\u00ed oceli. Pyrolytick\u00fd BN je zase jin\u00e1 t\u0159\u00edda: CVD desky a kel\u00edmky pro pr\u00e1ci s polovodi\u010di, velmi \u010dist\u00fd, velmi drah\u00fd. V\u011bt\u0161ina na\u0161ich pr\u016fmyslov\u00fdch zak\u00e1zek se st\u00e1le t\u00fdk\u00e1 hexagon\u00e1ln\u00edho pr\u00e1\u0161ku a tvar\u016f lisovan\u00fdch za tepla.<\/p>\n
h-BN nen\u00ed p\u0159i n\u00edzk\u00fdch teplot\u00e1ch \u017e\u00e1dn\u00fdm z\u00e1zrakem. P\u0159i teplot\u00e1ch pod p\u0159ibli\u017en\u011b 600 \u00b0C m\u00e1 grafit \u010dasto ni\u017e\u0161\u00ed koeficient t\u0159en\u00ed. BN se dost\u00e1v\u00e1 do veden\u00ed, jakmile grafit za\u010dne oxidovat. Vlhkost, olej a siln\u00e1, odlupuj\u00edc\u00ed se vrstva zni\u010d\u00ed i kvalitn\u00ed pr\u00e1\u0161ek. Nan\u00e1\u0161ejte tenkou, rovnom\u011brnou a suchou vrstvu a opakujte nan\u00e1\u0161en\u00ed, jakmile b\u00edl\u00e1 barva zmiz\u00ed. Pokud se jedn\u00e1 o taven\u00ed hlin\u00edku nebo ho\u0159\u010d\u00edku a n\u00e1stroj mus\u00ed z\u016fstat \u010dist\u00fd a elektricky neaktivn\u00ed, je hexagon\u00e1ln\u00ed nitrid boru mazivem, kter\u00e9 z\u016fstane na m\u00edst\u011b i pot\u00e9, co se grafit prom\u011bn\u00ed v CO\u2082.<\/p>","protected":false},"excerpt":{"rendered":"
Hexagonal Boron Nitride Is Graphite That Does Not Conduct and Does Not Burn Off at 600\u00b0C People call hexagonal boron […]<\/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":""}},"ngg_post_thumbnail":0,"footnotes":""},"categories":[4],"tags":[],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/boronnitrideceramic.com\/cs\/wp-json\/wp\/v2\/posts\/337"}],"collection":[{"href":"https:\/\/boronnitrideceramic.com\/cs\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/boronnitrideceramic.com\/cs\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/boronnitrideceramic.com\/cs\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/boronnitrideceramic.com\/cs\/wp-json\/wp\/v2\/comments?post=337"}],"version-history":[{"count":1,"href":"https:\/\/boronnitrideceramic.com\/cs\/wp-json\/wp\/v2\/posts\/337\/revisions"}],"predecessor-version":[{"id":338,"href":"https:\/\/boronnitrideceramic.com\/cs\/wp-json\/wp\/v2\/posts\/337\/revisions\/338"}],"wp:attachment":[{"href":"https:\/\/boronnitrideceramic.com\/cs\/wp-json\/wp\/v2\/media?parent=337"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/boronnitrideceramic.com\/cs\/wp-json\/wp\/v2\/categories?post=337"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/boronnitrideceramic.com\/cs\/wp-json\/wp\/v2\/tags?post=337"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}