\u013dudia naz\u00fdvaj\u00fa hexagon\u00e1lny nitrid b\u00f3ru \u201cbielym grafitom\u201d a t\u00e1to prez\u00fdvka je z\u00e1rove\u0148 u\u017eito\u010dn\u00e1 aj trochu nebezpe\u010dn\u00e1. U\u017eito\u010dn\u00e1 preto, lebo tento vrstevnat\u00fd kry\u0161t\u00e1l naozaj vyzer\u00e1 a na dotyk pripom\u00edna grafit. Nebezpe\u010dn\u00e1 preto, lebo grafit vedie elektrinu a m\u00f4\u017ee kontaminova\u0165 taveninu. Nitrid b\u00f3ru nem\u00e1 ani jednu z t\u00fdchto vlastnost\u00ed. Bol som svedkom toho, ako sa v z\u00e1vodoch pok\u00fa\u0161ali tieto dve l\u00e1tky pova\u017eova\u0165 za zamenite\u013en\u00e9, a potom str\u00e1vili t\u00fd\u017ede\u0148 vysvet\u013eovan\u00edm usadzovania uhl\u00edka, skratovan\u00fdch ohrieva\u010dov alebo povlaku, ktor\u00fd sa vyparil na vzduchu. Ak pracujete s vysok\u00fdmi teplotami, roztaven\u00fdm kovom alebo elektronikou, ktor\u00e1 nesmie skratova\u0165, BN je v tejto oblasti jedine\u010dn\u00fd.<\/p>\n
V priemysle m\u00e1 najv\u00e4\u010d\u0161\u00ed v\u00fdznam hexagon\u00e1lny nitrid b\u00f3ru (h-BN). Existuje aj kubick\u00fd nitrid b\u00f3ru \u2013 ide o supertvrd\u00fd materi\u00e1l pou\u017e\u00edvan\u00fd v rezn\u00fdch n\u00e1strojoch \u2013, ale je to in\u00fd produkt s in\u00fdm \u00fa\u010delom. Ke\u010f sa v v\u00fdkrese uv\u00e1dza \u201ckeramika BN\u201d, takmer v\u017edy sa t\u00fdm mysl\u00ed hexagon\u00e1lny materi\u00e1l: pr\u00e1\u0161ok, povlak, tvar vytvoren\u00fd lisovan\u00edm za tepla alebo pyrolytick\u00fd diel.<\/p>\n
h-BN je jedn\u00fdm z m\u00e1la materi\u00e1lov, ktor\u00e9 dobre ved\u00fa teplo a z\u00e1rove\u0148 p\u00f4sobia ako elektrick\u00e9 izolanty. Objemov\u00fd mern\u00fd odpor sa zvy\u010dajne pohybuje nad hodnotou 10\u00b9\u2074 ohm\u00b7cm. Dielektrick\u00e1 kon\u0161tanta sa pohybuje okolo hodnoty 4. Pr\u00e1ve t\u00e1to kombin\u00e1cia je d\u00f4vodom, pre\u010do sa tento materi\u00e1l pou\u017e\u00edva v chladi\u010doch, vysokoteplotn\u00fdch izolantoch a ako plnivo v polym\u00e9roch pre tepeln\u00e9 rozhrania. Grafit dok\u00e1\u017ee rozv\u00e1dza\u0165 teplo. Me\u010f dok\u00e1\u017ee rozv\u00e1dza\u0165 teplo. Ani jeden z t\u00fdchto materi\u00e1lov v\u0161ak nezabezpe\u010d\u00ed izol\u00e1ciu v\u00e1\u0161ho obvodu.<\/p>\n
Je tie\u017e nepri\u013enav\u00fd vo\u010di \u0161irokej \u0161k\u00e1le roztaven\u00fdch kovov a strusiek. Hlin\u00edk, zinok, me\u010f, mnoh\u00e9 druhy skla a ve\u013ek\u00e9 mno\u017estvo roztaven\u00fdch polovodi\u010dov sa na \u0148om neusadzuj\u00fa. Ak k tomu prid\u00e1me chemick\u00fa inertnos\u0165, z\u00edskame t\u00e9gliky, rozde\u013eovacie kr\u00fa\u017eky, bo\u010dn\u00e9 prie\u010dky, trysky a uvo\u013e\u0148ovacie povlaky, ktor\u00e9 zost\u00e1vaj\u00fa \u010distej\u0161ie ako grafit alebo oxidov\u00e1 keramika.<\/p>\n
\u010ealej je tu vlastnos\u0165, ktor\u00fa \u013eudia v praxi podce\u0148uj\u00fa: obrobite\u013enos\u0165. BN lisovan\u00fd za tepla sa d\u00e1 s\u00fastru\u017ei\u0165, fr\u00e9zova\u0165 a v\u0155ta\u0165 be\u017en\u00fdmi n\u00e1strojmi. Prototyp up\u00ednacieho pr\u00edpravku m\u00f4\u017eete vyrobi\u0165 za jedno popoludnie, namiesto toho, aby ste \u010dakali na diamantov\u00e9 br\u00fasenie. Hustota je n\u00edzka, zvy\u010dajne okolo 1,8\u20132,1 g\/cm\u00b3 u hor\u00faco lisovan\u00fdch tried, tak\u017ee diely s\u00fa \u013eahk\u00e9. Odolnos\u0165 vo\u010di tepeln\u00fdm \u0161okom je vynikaj\u00faca, preto\u017ee \u0161trukt\u00fara sa m\u00f4\u017ee mierne pos\u00fava\u0165 a roz\u0165a\u017enos\u0165 je v u\u017eito\u010dn\u00fdch smeroch mierna.<\/p>\n
Teplotn\u00e1 odolnos\u0165 z\u00e1vis\u00ed od atmosf\u00e9ry. Na vzduchu sa oxid\u00e1cia st\u00e1va v\u00fdznamnou pribli\u017ene pri teplot\u00e1ch 900\u20131000 \u00b0C. V dus\u00edku, arg\u00f3ne alebo vo v\u00e1kuu m\u00f4\u017eu druhy bez spojiva dosahova\u0165 ove\u013ea vy\u0161\u0161ie teploty \u2014 v mnoh\u00fdch peciach a pri taven\u00ed aj v\u00fdrazne nad 1800 \u00b0C, pri\u010dom pyrolytick\u00fd BN sa be\u017ene pou\u017e\u00edva pri n\u00e1ro\u010dn\u00fdch v\u00e1kuov\u00fdch pr\u00e1cach.<\/p>\n
Pr\u00e1ve v tomto bode m\u00f4\u017eu technick\u00e9 listy na webov\u00fdch str\u00e1nkach sp\u00f4sobi\u0165 \u013eu\u010fom probl\u00e9my.<\/p>\n
BN lisovan\u00fd za tepla je be\u017ene pou\u017e\u00edvan\u00fd materi\u00e1l. Pr\u00e1\u0161ok sa pri vysokej teplote lisuje do polotovarov, ktor\u00e9 sa n\u00e1sledne obr\u00e1baj\u00fa. Niektor\u00e9 druhy pou\u017e\u00edvaj\u00fa ako spojivo oxid b\u00f3ru alebo boritan v\u00e1penat\u00fd. Tieto sa \u013eah\u0161ie zhustia a s\u00fa lacnej\u0161ie, av\u0161ak vlhkos\u0165 a ur\u010dit\u00e9 chemick\u00e9 l\u00e1tky m\u00f4\u017eu spojivo po\u0161kodi\u0165. Druhy bez spojiva alebo s dif\u00fazne spojen\u00fdmi zlo\u017ekami s\u00fa drah\u0161ie a lep\u0161ie zvl\u00e1daj\u00fa taveniny citliv\u00e9 na \u010distotu. Vlastnosti s\u00fa tie\u017e anizotropn\u00e9: tepeln\u00e1 vodivos\u0165 a pevnos\u0165 sa m\u00f4\u017eu l\u00ed\u0161i\u0165 v smere rovnobe\u017enom a kolmom na smer lisovania. Ak ignorujete orient\u00e1ciu, \u201cdobr\u00fd\u201d diel sa m\u00f4\u017ee aj tak praskn\u00fa\u0165 alebo prehria\u0165 v nespr\u00e1vnej osi.<\/p>\n
Pyrolytick\u00fd BN, alebo PBN, je \u00faplne in\u00e1 l\u00e1tka. Vyr\u00e1ba sa met\u00f3dou chemick\u00e9ho nan\u00e1\u0161ania z parnej f\u00e1zy, nie lisovan\u00edm. \u010cistota m\u00f4\u017ee presiahnu\u0165 99,99%. Hustota sa bl\u00ed\u017ei teoretickej hodnote. Odply\u0148ovanie je mimoriadne n\u00edzke. Tepeln\u00e1 vodivos\u0165 v rovine m\u00f4\u017ee dosiahnu\u0165 150\u2013220 W\/m\u00b7K, zatia\u013e \u010do vodivos\u0165 cez hr\u00fabku kles\u00e1 na nieko\u013eko wattov. T\u00e1to anizotropia je v\u00fdhodou pri v\u00fdrobe lod\u00ed, oblo\u017eenia a MBE zariaden\u00ed. Nie je to v\u0161ak v\u00fdhoda, ak potrebujete hrub\u00fd, lacn\u00fd a \u013eahko obrobite\u013en\u00fd blok. PBN je ur\u010den\u00fd pre vysokochrast\u00e9, tenkostenn\u00e9 a v\u00e1kuovo kritick\u00e9 aplik\u00e1cie.<\/p>\n
Pr\u00e1\u0161ky a povlaky vykon\u00e1vaj\u00fa ve\u013ek\u00fa \u010das\u0165 pr\u00e1ce v pozad\u00ed. Povlaky z BN na lisovac\u00edch maticiach, form\u00e1ch, \u017e\u013eaboch a zv\u00e1rac\u00edch pr\u00edpravkoch zabra\u0148uj\u00fa prilepeniu kovu. V plastoch a tepeln\u00fdch podlo\u017ek\u00e1ch zvy\u0161uje BN vo forme do\u0161ti\u010diek vodivos\u0165 bez toho, aby sa zmes stala vodi\u010dom. Kompozitn\u00e9 zmesi \u2013 BN s karbidom krem\u00edka alebo in\u00fdmi keramick\u00fdmi materi\u00e1lmi \u2013 sa pou\u017e\u00edvaj\u00fa v pr\u00edpadoch, ke\u010f je potrebn\u00e1 vy\u0161\u0161ia odolnos\u0165 proti opotrebeniu, ne\u017e ak\u00fa m\u00f4\u017ee poskytn\u00fa\u0165 \u010dist\u00fd BN. Typick\u00fdm pr\u00edkladom s\u00fa materi\u00e1ly typu ZSBN: st\u00e1le s\u00fa k\u013azav\u00e9 a tepelne u\u017eito\u010dn\u00e9, ale odolnej\u0161ie pri k\u013azavom kontakte.<\/p>\n
Spracovanie kovov a skla je pre tento materi\u00e1l prirodzen\u00fdm uplatnen\u00edm. T\u00e9gliky, \u017e\u013eaby, odlievan\u00e9 diely, ochrana termo\u010dl\u00e1nkov a uvo\u013e\u0148ovacie povlaky \u2013 to v\u0161etko sa spolieha na nezm\u00e1\u010dav\u00fd povrch. Pri v\u00fdrobe polovodi\u010dov a vo v\u00e1kuov\u00fdch procesoch sa pou\u017e\u00edvaj\u00fa PBN lodi\u010dky, podpery ohrieva\u010dov a komponenty kom\u00f4r, preto\u017ee kontamin\u00e1cia uhl\u00edkom je neprijate\u013en\u00e1 a izol\u00e1cia si zachov\u00e1va d\u00f4le\u017eitos\u0165 aj pri vysok\u00fdch teplot\u00e1ch. V\u00fdrobcovia pec\u00ed uprednost\u0148uj\u00fa BN pri v\u00fdrobe up\u00ednac\u00edch pr\u00edpravkov, nastavovac\u00edch zariaden\u00ed a izola\u010dn\u00fdch prvkov, preto\u017ee sa tieto diely \u013eahko opracov\u00e1vaj\u00fa a odol\u00e1vaj\u00fa cyklick\u00e9mu nam\u00e1haniu. V elektronike sa BN pou\u017e\u00edva ako plnivo v pr\u00edpadoch, ke\u010f mus\u00ed puzdro alebo podlo\u017eka odv\u00e1dza\u0165 teplo a z\u00e1rove\u0148 si zachova\u0165 dielektrick\u00e9 vlastnosti.<\/p>\n
Videl som, \u017ee jednoduch\u00e1 zmena povrchovej \u00fapravy dok\u00e1\u017ee viac ako moderniz\u00e1cia materi\u00e1lu. Grafitov\u00e1 forma, ktor\u00e1 sa pri ka\u017edom v\u00fdstrele po\u0161krabala, sa m\u00f4\u017ee sta\u0165 v\u00fdrobn\u00fdm n\u00e1strojom s kvalitnou uvo\u013e\u0148ovacou vrstvou BN. Kovov\u00e1 up\u00ednka, ktor\u00e1 sa prir\u00e1stla k hlin\u00edku, m\u00f4\u017ee vydr\u017ea\u0165 cel\u00fa zmenu namiesto jednej hodiny. To nie je len te\u00f3ria. Preto si tento materi\u00e1l pam\u00e4taj\u00fa \u00fadr\u017eb\u00e1rske t\u00edmy.<\/p>\n
Keramika z nitridu b\u00f3ru nie je odoln\u00e1 vo\u010di opotrebeniu v tom zmysle, ako je tomu v pr\u00edpade oxidu hlinit\u00e9ho alebo karbidu krem\u00edka. Je relat\u00edvne m\u00e4kk\u00e1. Ak ide o abr\u00e1ziu v kalovej zmesi alebo tvrd\u00fd k\u013azav\u00fd kontakt, pou\u017eite kompozit alebo zvo\u013ete in\u00fd materi\u00e1l. Niektor\u00e9 druhy spoj\u00edv m\u00f4\u017eu hydratova\u0165. Ak nech\u00e1te diel spojen\u00fd B\u2082O\u2083 vo vlhkej skladovacej miestnosti, m\u00f4\u017ee d\u00f4js\u0165 k pr\u00e1\u0161kovaniu alebo strate pevnosti. Oxid\u00e1cia na vzduchu je re\u00e1lna; ne\u0161pecifikujte BN pre dlhodob\u00e9 vystavenie otvoren\u00e9mu plame\u0148u len preto, \u017ee hodnota v inertnej atmosf\u00e9re vyzerala p\u00f4sobivo. A s PBN sa nespr\u00e1vajte ako s materi\u00e1lom lisovan\u00fdm za tepla. Preplat\u00edte a aj tak nedosiahnete po\u017eadovan\u00fd tvar.<\/p>\n
\u010eal\u0161ou chybou je pou\u017eitie keramiky BN len preto, \u017ee niekto spomenul \u201cvysokoteplotn\u00fa keramiku\u201d. Oxid hlinit\u00fd, nitrid krem\u00edka a karbid krem\u00edka vynikaj\u00fa ka\u017ed\u00fd vo svojej oblasti. BN je vhodn\u00fd v pr\u00edpadoch, ke\u010f potrebujete izol\u00e1ciu spolu s rozvodom tepla, ne\u0161m\u00fdkav\u00e9 vlastnosti alebo diel, ktor\u00fd je mo\u017en\u00e9 po lisovan\u00ed \u010falej obr\u00e1ba\u0165.<\/p>\n
Najsk\u00f4r uve\u010fte formu: pr\u00e1\u0161kov\u00e1, povlakov\u00e1, lisovan\u00e1 za tepla, kompozitn\u00e1 alebo PBN. Potom uve\u010fte atmosf\u00e9ru, maxim\u00e1lnu teplotu a chemick\u00e9 zlo\u017eenie. Ak ide o roztaven\u00fd kov, uve\u010fte, o ktor\u00fd kov ide. Ak ide o v\u00e1kuov\u00fa technol\u00f3giu, op\u00fdtajte sa na obsah pojiva a odply\u0148ovanie. Ak je diel obr\u00e1ban\u00fd zo sochory, op\u00fdtajte sa na smer lisovania. Ak ide o povlak, op\u00fdtajte sa na syst\u00e9m pojiva, hr\u00fabku vrstvy a interval op\u00e4tovn\u00e9ho nan\u00e1\u0161ania.<\/p>\n
Nitrid b\u00f3ru nie je \u017eiadny z\u00e1zra\u010dn\u00fd pr\u00e1\u0161ok a nenahr\u00e1dza v\u0161etky \u017eiaruvzdorn\u00e9 materi\u00e1ly. Je to materi\u00e1l, po ktorom siahnete vtedy, ke\u010f je grafit pr\u00edli\u0161 zne\u010disten\u00fd alebo pr\u00edli\u0161 vodiv\u00fd, a ke\u010f sa be\u017en\u00e1 oxidov\u00e1 keramika navlh\u010duje, prilepuje alebo ju nie je mo\u017en\u00e9 v\u010das obrobi\u0165. Ak zvol\u00edte spr\u00e1vnu kvalitu, bude to vyzera\u0165 takmer a\u017e pr\u00edli\u0161 jednoducho. Ak sa v\u0161ak pom\u00fdlite, budete presved\u010den\u00ed, \u017ee technick\u00fd list klamal. Technick\u00fd list pravdepodobne neklamal. Aplik\u00e1cia jednoducho vy\u017eadovala vhodnej\u0161iu vo\u013ebu.<\/p>","protected":false},"excerpt":{"rendered":"
White Graphite, Done Right: A Practical Guide to Boron Nitride People call hexagonal boron nitride \u201cwhite graphite,\u201d and that nickname […]<\/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\/sk\/wp-json\/wp\/v2\/posts\/333"}],"collection":[{"href":"https:\/\/boronnitrideceramic.com\/sk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/boronnitrideceramic.com\/sk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/boronnitrideceramic.com\/sk\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/boronnitrideceramic.com\/sk\/wp-json\/wp\/v2\/comments?post=333"}],"version-history":[{"count":1,"href":"https:\/\/boronnitrideceramic.com\/sk\/wp-json\/wp\/v2\/posts\/333\/revisions"}],"predecessor-version":[{"id":334,"href":"https:\/\/boronnitrideceramic.com\/sk\/wp-json\/wp\/v2\/posts\/333\/revisions\/334"}],"wp:attachment":[{"href":"https:\/\/boronnitrideceramic.com\/sk\/wp-json\/wp\/v2\/media?parent=333"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/boronnitrideceramic.com\/sk\/wp-json\/wp\/v2\/categories?post=333"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/boronnitrideceramic.com\/sk\/wp-json\/wp\/v2\/tags?post=333"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}