Po daugiau nei dvide\u0161imties met\u0173, per kuriuos rinkdavausi tepalus ir funkcinius miltelius, skirtus metalo formavimui, keramikai ir elektronikai, borono nitrido miltelius \u0117miau laikyti viena i\u0161 t\u0173 med\u017eiag\u0173, kurios, kai jas i\u0161 tikr\u0173j\u0173 pradedi naudoti, tyliai pranoksta l\u016bkes\u010dius. \u017dmon\u0117s da\u017enai j\u012f vadina \u201cbaltuoju grafitu\u201d, nes jo \u0161e\u0161iakamp\u0117 kristalin\u0117 strukt\u016bra popieriuje atrodo pana\u0161i, ta\u010diau praktikoje jis elgiasi visi\u0161kai kitaip \u2013 ir da\u017eniausiai geriau \u2013 kai pakyla temperat\u016bra arba kai anglies priemai\u0161os yra nepriimtinos. A\u0161 atlikau bandymus, steb\u0117jau, kaip gamybos linijos pereina prie jo naudojimo, ir pasteb\u0117jau skirtum\u0105 \u0161tamp\u0173 tarnavimo laiko, pavir\u0161iaus kokyb\u0117s ir proceso stabilumo at\u017evilgiu. Tai ne visada pigiausias variantas, ta\u010diau tinkamose vietose jis atsipirks.<\/p>\n
\u0160e\u0161iakampis boro nitridas (h-BN) gaunamas, kai boro oksidas arba borono r\u016bg\u0161tis reaguoja su amoniaku arba azotu esant temperat\u016brai, vir\u0161ijan\u010diai 1400 \u00b0C. Gautas milteliai yra balti, mink\u0161ti ir plok\u0161teli\u0173 formos, o j\u0173 sluoksniai lengvai slysta vienas ant kito. D\u0117l \u0161ios sluoksnin\u0117s strukt\u016bros med\u017eiaga pasi\u017eymi puikiomis tepimo savyb\u0117mis, ta\u010diau, skirtingai nuo grafito, ji i\u0161lieka stabili ore iki ma\u017edaug 1000 \u00b0C, o inertin\u0117je aplinkoje \u2013 gerokai vir\u0161 1400 \u00b0C. Be to, tai yra elektros izoliatorius, turintis keramikai b\u016bding\u0105 pakankam\u0105 \u0161ilumos laidum\u0105 \u2013 apie 20\u201330 W\/m\u00b7K plok\u0161teli\u0173 plok\u0161tumoje. D\u0117l \u0161i\u0173 savybi\u0173 jis yra naudingas ten, kur grafitas oksiduot\u0173si, \u012fne\u0161t\u0173 anglies arba sukelt\u0173 elektros problem\u0173.<\/p>\n
Kar\u0161tojo kalimo ir ekstruzijos procesuose boro nitrido milteliai tapo vienu i\u0161 mano m\u0117gstamiausi\u0173 atskyrimo agent\u0173. Grafitas puikiai veikia vidutin\u0117se temperat\u016brose, ta\u010diau vir\u0161ijus 700\u2013800 \u00b0C jis pradeda degti ir gali palikti nuos\u0117d\u0173, kurios pablogina pavir\u0161iaus apdail\u0105. Viename aliuminio ekstruzijos bandyme, kuriame dalyvavau, lygindome standartin\u0119 grafito ir vandens dispersij\u0105 su 15 % h-BN dispersija, naudodami tuos pa\u010dius 6061 lydinio ruo\u0161inius. I\u0161presavus 4 000 ruo\u0161ini\u0173, grafitu padengtos formos tur\u0117jo matom\u0173 nusid\u0117v\u0117jimo grioveli\u0173 ir jas reik\u0117jo poliruoti, o h-BN padengtos formos vis dar tur\u0117jo lyg\u0173 pavir\u0161i\u0173 ir pagamintos detal\u0117s pasi\u017eym\u0117jo ma\u017eesniu pavir\u0161iaus \u0161iurk\u0161tumu (Ra 0,8 \u00b5m, palyginti su 1,6 \u00b5m). Be to, h-BN vidutini\u0161kai ma\u017edaug 12 % suma\u017eino ekstruzijai reikaling\u0105 j\u0117g\u0105, o tai leido suma\u017einti presavimo energijos s\u0105naudas ir sutrumpinti prastovas, reikalingas form\u0173 keitimui.<\/p>\n
Pana\u0161\u0173 teigiam\u0105 poveik\u012f pasteb\u0117jome ir kar\u0161to ner\u016bdijan\u010dio plieno kalimo procese 950 \u00b0C temperat\u016broje. Atlikus 200 detali\u0173 lyginam\u0105j\u012f bandym\u0105 paai\u0161k\u0117jo, kad h-BN alyva sutept\u0173 \u0161tamp\u0173 nusid\u0117v\u0117jimo gylis, i\u0161matuotas profilometru po gamybos ciklo, buvo 28 % ma\u017eesnis. Detal\u0117s taip pat buvo \u0161varesn\u0117s \u2013 be tamsi\u0173 grafito d\u0117mi\u0173, d\u0117l kuri\u0173 kartais tenka imtis papildom\u0173 valymo veiksm\u0173. Tr\u016bkumas buvo kaina: h-BN dispersija litrui kainavo apie 2,5 karto brangiau, ta\u010diau ilgesnis \u0161tamp\u0173 tarnavimo laikas ir suma\u017e\u0117j\u0119s perdarymo poreikis \u0161ioje konkre\u010dioje u\u017eduotyje tai su kaupu kompensavo.<\/p>\n
Keramikos ir ugniai atspari\u0173 med\u017eiag\u0173 gamyboje boro nitrido milteliai da\u017enai naudojami kaip sukepinimo priedas arba kaip auk\u0161tos temperat\u016bros tepalas krosni\u0173 \u012frangai. A\u0161 j\u012f naudoju silicio nitrido ir aliuminio oksido kompozituose, kur po sukepinimo reik\u0117jo u\u017etikrinti geresn\u012f apdirbamum\u0105. \u012emai\u0161ius 3\u20135 % smulki\u0173 h-BN daleli\u0173 (vidutinis daleli\u0173 dydis 5\u201310 \u00b5m), pager\u0117jo i\u0161degt\u0173 detali\u0173 \u0161lifavimo lengvumas, beveik neprarandant stiprumo. Vieno vidinio palyginimo metu nustatyta, kad partijos, kuri\u0173 sud\u0117tyje buvo h-BN, \u0161lifavimui deimantiniu disku reik\u0117jo 18 % ma\u017eiau laiko, palyginti su kontroline partija, o kra\u0161t\u0173 skilin\u0117jimas pastebimai suma\u017e\u0117jo.<\/p>\n
\u0160ilumos valdymas yra dar viena sritis, kurioje \u0161i med\u017eiaga ai\u0161kiai parodo savo prana\u0161umus. Elektronikos pramon\u0117je h-BN naudojamas kaip u\u017epildas \u0161iluminiuose s\u0105sajos med\u017eiagose ir hermetizavimo mi\u0161iniuose, nes jis perduoda \u0161ilum\u0105, tuo pa\u010diu i\u0161lieka elektros izoliatorius. Paprastame laboratoriniame palyginime, kur\u012f atlikome prie\u0161 kelerius metus, silikonin\u0117 alyva, u\u017epildyta 30 % aliuminio oksidu, pasiek\u0117 apie 1,1 W\/m\u00b7K. Ta pati baz\u0117, u\u017epildyta 30 % % h-BN (stambesni\u0173 plok\u0161teli\u0173 r\u016b\u0161ies), identi\u0161komis bandymo s\u0105lygomis, naudojant apsaugot\u0105 \u0161ilumos srauto matuokl\u012f, pasiek\u0117 2,4 W\/m\u00b7K. Be to, h-BN versija \u017eemose temperat\u016brose i\u0161liko mink\u0161tesn\u0117, o tai suma\u017eino kontaktin\u0119 var\u017e\u0105 ant nelygi\u0173 pavir\u0161i\u0173.<\/p>\n
\u017dinoma, boro nitridas n\u0117ra stebuklinga med\u017eiaga. Jis kainuoja brangiau nei grafitas ar talkas, o labai smulkios jo r\u016b\u0161ys gali dulk\u0117ti, tod\u0117l dirbant su jomis b\u016btina u\u017etikrinti ger\u0105 v\u0117dinim\u0105. Kai kuriose metalo formavimo srityse, kur reikalingas ypatingai didelis sl\u0117gis, molibdeno disulfidas arba specializuoti sintetiniai tepalai vis dar gali pranokti j\u012f vien tik trinties koeficiento at\u017evilgiu. Daleli\u0173 dydis ir grynumas yra labai svarb\u016bs \u2013 stambesn\u0117s r\u016b\u0161ys u\u017etikrina geresn\u012f atsiskyrim\u0105, bet prastesn\u0119 dispersij\u0105, o auk\u0161to grynumo r\u016b\u0161ys yra b\u016btinos elektronikos ar kosmetikos pramon\u0117je.<\/p>\n
I\u0161 patirties \u017einau, kad geriausi rezultatai pasiekiami, kai med\u017eiagos r\u016b\u0161is parenkama atsi\u017evelgiant \u012f konkre\u010di\u0105 u\u017eduot\u012f. Kar\u0161to metalo formavimui paprastai nurodau 10\u201320 \u00b5m dyd\u017eio plok\u0161teles, pasi\u017eymin\u010dias geru tekamumu. Terminiams u\u017epildams ar kosmetikos gaminiams geriau tinka ma\u017eesn\u0117s nei 10 \u00b5m ar net ma\u017eesn\u0117s nei mikrono dyd\u017eio r\u016b\u0161ys su kontroliuojamu pavir\u0161iaus plotu. Visada atlikite tinkamus bandymus su savo tikr\u0105ja \u012franga ir med\u017eiagomis, o ne pasikliaukite bendro pob\u016bd\u017eio technini\u0173 duomen\u0173 lapais. Tais atvejais, kai taip dar\u0117me, boro nitrido milteliai ne kart\u0105 u\u017etikrino matom\u0105 \u012franki\u0173 tarnavimo laiko, energijos suvartojimo ar produkto kokyb\u0117s pager\u0117jim\u0105, kuris pateisino didesnes med\u017eiag\u0173 s\u0105naudas.<\/p>\n
Jis niekada nepakeis vis\u0173 kit\u0173 tepal\u0173 ar u\u017epild\u0173, ta\u010diau kai procese reikalinga auk\u0161ta temperat\u016bra, \u0161varumas arba elektrin\u0117 izoliacija kartu su \u0161ilumin\u0117mis savyb\u0117mis, boro nitrido milteliai u\u017esitarnavo nuolatin\u0119 viet\u0105 mano \u012franki\u0173 rinkinyje. Svarbiausia, kaip ir bet kurios specialiosios med\u017eiagos atveju, yra suprasti, kaip ji i\u0161 tikr\u0173j\u0173 veikia j\u016bs\u0173 konkre\u010diomis s\u0105lygomis, tinkamai j\u0105 i\u0161bandyti ir naudoti ten, kur na\u0161umo padid\u0117jimas yra realus, o ne tik numanomas.<\/p>","protected":false},"excerpt":{"rendered":"
After more than twenty years specifying lubricants and functional powders for metal forming, ceramics, and electronics, I\u2019ve come to treat […]<\/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":[11],"tags":[],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/boronnitrideceramic.com\/lt\/wp-json\/wp\/v2\/posts\/329"}],"collection":[{"href":"https:\/\/boronnitrideceramic.com\/lt\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/boronnitrideceramic.com\/lt\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/boronnitrideceramic.com\/lt\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/boronnitrideceramic.com\/lt\/wp-json\/wp\/v2\/comments?post=329"}],"version-history":[{"count":1,"href":"https:\/\/boronnitrideceramic.com\/lt\/wp-json\/wp\/v2\/posts\/329\/revisions"}],"predecessor-version":[{"id":330,"href":"https:\/\/boronnitrideceramic.com\/lt\/wp-json\/wp\/v2\/posts\/329\/revisions\/330"}],"wp:attachment":[{"href":"https:\/\/boronnitrideceramic.com\/lt\/wp-json\/wp\/v2\/media?parent=329"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/boronnitrideceramic.com\/lt\/wp-json\/wp\/v2\/categories?post=329"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/boronnitrideceramic.com\/lt\/wp-json\/wp\/v2\/tags?post=329"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}