Ahoj Jacku, tam v Los Angeles, kde jedin\u00e9 to\u010d\u00edc\u00ed se koule, na kter\u00e9 si vzpomene\u0161, jsou ty v pokeru s vysok\u00fdmi s\u00e1zkami nebo kola na tv\u00e9m aut\u011b jedouc\u00edm po Sunset Boulevardu. Ale v m\u00fdch kon\u010din\u00e1ch - 40 let v keramick\u00e9m pr\u016fmyslu, od leteck\u00fdch hang\u00e1r\u016f v Seattlu a\u017e po automobilky v Detroitu - jsou koule z nitridu k\u0159em\u00edku (Si3N4) skute\u010dn\u00fdmi high-rollery. Tyto p\u0159esn\u00e9 kuli\u010dky nejsou jen kuli\u010dky, ale m\u011bn\u00ed pravidla hry v lo\u017eisc\u00edch, ventilech a technologi\u00edch, kter\u00e9 vy\u017eaduj\u00ed rychlost, teplo a zrnitost, ani\u017e by se vzdaly. Specifikoval jsem je pro tryskov\u00e9 motory, kter\u00e9 \u0159vou p\u0159i 50 000 ot\u00e1\u010dk\u00e1ch za minutu, a elektromotory, kter\u00e9 ti\u0161e hu\u010d\u00ed milion kilometr\u016f. V tomto \u010dl\u00e1nku je rozeberu jako u piva v d\u00edln\u011b: co jsou za\u010d, jak je vyr\u00e1b\u00edme, pro\u010d jsou nep\u0159ekonateln\u00e9 a jak\u00e1 v\u00edt\u011bzstv\u00ed p\u0159inesly v re\u00e1ln\u00e9m sv\u011bt\u011b. Budeme m\u00edt kolem 800 slov, p\u0159\u00edmo ze sady n\u00e1\u0159ad\u00ed.<\/p>\n
<\/p>\n
Za prv\u00e9, kuli\u010dky nitridu k\u0159em\u00edku jsou vysoce v\u00fdkonn\u00e9 keramick\u00e9 kuli\u010dky o pr\u016fm\u011bru obvykle 1 mm a\u017e 50 mm, vyroben\u00e9 z neoxidov\u00e9 keramiky, kter\u00e1 je tvrd\u0161\u00ed ne\u017e steak za dva dolary. Si3N4 se syntetizuje z k\u0159em\u00edku a dus\u00edku a vytv\u00e1\u0159\u00ed kovalentn\u00ed krystalovou m\u0159\u00ed\u017eku, kter\u00e1 je hust\u00e1 (3,2 g\/cm\u00b3), tvrd\u00e1 (HV 1400-1700) a m\u00e1 lomovou hou\u017eevnatost kolem 6-7 MPa-m^{1\/2} - tedy lep\u0161\u00ed ne\u017e v\u011bt\u0161ina keramiky, co\u017e znamen\u00e1, \u017ee vydr\u017e\u00ed n\u00e1raz bez rozt\u0159\u00ed\u0161t\u011bn\u00ed. N\u00edzk\u00e1 tepeln\u00e1 rozta\u017enost (3 x 10^-6\/K) je udr\u017euje stabiln\u00ed p\u0159i teplotn\u00edch v\u00fdkyvech a na vzduchu zvl\u00e1dnou a\u017e 1200 \u00b0C, ani\u017e by oxidovaly. Elektrick\u00e1 izolace? \u0160pi\u010dkov\u00e1, \u017e\u00e1dn\u00e9 v\u00ed\u0159iv\u00e9 proudy v magnetick\u00e9m poli. V roce 86 jsem se nechal un\u00e9st projektem turb\u00edny: ocelov\u00e9 kuli\u010dky se pod vlivem tepla deformovaly, tihle Si3N4 drs\u0148\u00e1ci b\u011b\u017eeli v pohod\u011b a v\u011brn\u011b.<\/p>\n
Jejich v\u00fdroba je sm\u011bsic\u00ed v\u011bdy a potu. Za\u010d\u00edn\u00e1me s ultra\u010dist\u00fdm k\u0159em\u00edkov\u00fdm pr\u00e1\u0161kem nitridovan\u00fdm p\u0159i 1 400 \u00b0C v \u010dpavku za vzniku Si3N4, pak jej jemn\u011b rozemeleme pomoc\u00ed sp\u00e9kac\u00edch p\u0159\u00edsad, jako je yttria nebo oxid hlinit\u00fd (5-10% pro zhu\u0161t\u011bn\u00ed). Sm\u011bs se lisuje do zelen\u00fdch kuli\u010dek izostatick\u00fdm lisov\u00e1n\u00edm - rovnom\u011brn\u00fdm tlakem ze v\u0161ech stran pro dosa\u017een\u00ed dokonal\u00e9 kulatosti. Pak n\u00e1sleduje ohe\u0148: izostatick\u00e9 lisov\u00e1n\u00ed za tepla (HIP) p\u0159i teplot\u011b 1 700-1 900 \u00b0C pod tlakem 200 MPa argonu vytla\u010d\u00ed p\u00f3ry a dos\u00e1hne hustoty 99%+. Po sp\u00e9k\u00e1n\u00ed se diamantov\u00fdm lapov\u00e1n\u00edm vyle\u0161t\u00ed na zrcadlovou Ra 0,01 \u00b5m-sf\u00e9ricitu v rozmez\u00ed 0,0005 mm. St\u00e1l jsem v \u010dist\u00fdch prostor\u00e1ch v Japonsku, kde lasery kontroluj\u00ed ka\u017edou kuli\u010dku; jedin\u00e1 vada a je to \u0161rot. T\u0159\u00eddy se li\u0161\u00ed: sp\u00e9kan\u00e9 tlakem plynu pro ekonomick\u00e9 \u00fa\u010dely, HIP pro elitn\u00ed v\u00fdkony. Vlastn\u00ed doping zlep\u0161uje vlastnosti - nap\u0159\u00edklad p\u0159id\u00e1n\u00edm oxidu hlinit\u00e9ho pro lep\u0161\u00ed opot\u0159eben\u00ed.<\/p>\n
D\u00edky t\u011bmto vlastnostem jsou kuli\u010dky Si3N4 legendami. Polovi\u010dn\u00ed hustota oceli sni\u017euje odst\u0159ediv\u00e9 s\u00edly o 60%, tak\u017ee se lo\u017eiska ot\u00e1\u010dej\u00ed o 20-50% rychleji s men\u0161\u00edm mno\u017estv\u00edm maziva. \u00danavov\u00e1 \u017eivotnost? 10x v\u00edce ne\u017e ocel ve valiv\u00e9m kontaktu. Koroze? Nepodl\u00e9haj\u00ed kyselin\u00e1m, sol\u00edm a vod\u011b - ide\u00e1ln\u00ed pro n\u00e1mo\u0159n\u00ed nebo chemick\u00e9 pr\u00e1ce. Tepeln\u00e1 vodivost (20-30 W\/m-K) rychle odv\u00e1d\u00ed teplo. P\u0159i testech, kter\u00e9 jsem provedl, p\u0159e\u017eila kuli\u010dka Si3N4 10 milion\u016f cykl\u016f p\u0159i 10 000 ot\u00e1\u010dk\u00e1ch za minutu, zat\u00edmco ocel se unavila p\u0159i 1 milionu. K\u0159ehk\u00e1? Ano, ale konstruovan\u00e9 hybridy (keramick\u00e9 kuli\u010dky, ocelov\u00e9 dr\u00e1hy) to zm\u00edr\u0148uj\u00ed. Cena: $5-50 za kuli\u010dku, ale n\u00e1vratnost investice je obrovsk\u00e1.<\/p>\n
Aplikace? Nebe je limit. Hybridn\u00ed lo\u017eiska dominuj\u00ed: zubn\u00ed vrta\u010dky p\u0159i 400 000 ot\u00e1\u010dk\u00e1ch za minutu, obr\u00e1b\u011bc\u00ed stroje p\u0159i 60 000. Pom\u00e1hal jsem CNC d\u00edln\u011b v Kalifornii p\u0159ej\u00edt na Si3N4; vibrace klesly o 40%, povrchov\u00e1 \u00faprava se zlep\u0161ila o 25%. Elektromobily je miluj\u00ed - Tesla a Porsche pou\u017e\u00edvaj\u00ed hybridy pro n\u00e1boje kol, \u010d\u00edm\u017e sni\u017euj\u00ed neodpru\u017eenou hmotnost a zvy\u0161uj\u00ed dojezd. Letectv\u00ed a kosmonautika: hlavn\u00ed h\u0159\u00eddele proudov\u00fdch motor\u016f, kde Si3N4 zvl\u00e1d\u00e1 800 \u00b0C a p\u0159et\u00ed\u017een\u00ed. Zdravotnictv\u00ed: MRI skenery, \u017e\u00e1dn\u00e9 magnetick\u00e9 ru\u0161en\u00ed. Ventily a \u010derpadla: kontroln\u00ed kuli\u010dky ve vst\u0159ikova\u010d\u00edch paliva nebo kalov\u00fdch \u010derpadlech, kter\u00e9 3x p\u0159ekon\u00e1vaj\u00ed karbid. V\u00fdjime\u010dn\u00fd p\u0159\u00edpad: p\u0159evodovka v\u011btrn\u00e9 turb\u00edny, kterou jsem konzultoval na Mojave. Ocelov\u00e9 kuli\u010dky se od slan\u00e9ho vzduchu kazily; Si3N4 fungoval 8 let bez \u00fadr\u017eby a u\u0161et\u0159il $200 tis\u00edc na turb\u00ednu.<\/p>\n
Pro\u010d Si3N4 m\u00edsto zirkonu nebo oxidu hlinit\u00e9ho? Zirkonium je tvrd\u0161\u00ed (K1c 10 MPa-m^{1\/2}), ale hutn\u011bj\u0161\u00ed a dra\u017e\u0161\u00ed, f\u00e1ze nestabiln\u00ed nad 200 \u00b0C. Hlin\u00edk je tvrd\u0161\u00ed, ale k\u0159ehk\u00fd jako sklo. Si3N4 je v rovnov\u00e1ze: lehk\u00fd, pevn\u00fd, hork\u00fd. Oproti oceli: \u017e\u00e1dn\u00e1 koroze, m\u00e9n\u011b zbytk\u016f p\u0159i opot\u0159eben\u00ed, del\u0161\u00ed \u017eivotnost maziva. Ekologick\u00fd bonus: leh\u010d\u00ed sou\u010d\u00e1sti sni\u017euj\u00ed spot\u0159ebu paliva v letadlech a automobilech. V testu hybridn\u00edho elektromotoru sn\u00ed\u017eil Si3N4 energetick\u00e9 ztr\u00e1ty o 15%.<\/p>\n
Spr\u00e1vn\u00fd v\u00fdb\u011br vy\u017eaduje zku\u0161enosti. Shodn\u00fd stupe\u0148 k zat\u00ed\u017een\u00ed: ABEC 5-9 pro p\u0159esnost. Tolerance velikosti: G5 nebo lep\u0161\u00ed (odchylka 0,000125 mm). Pro vysok\u00e9 rychlosti zvolte jemnozrnn\u00e9 HIP. V\u017edy p\u00e1rujte s kompatibiln\u00edmi z\u00e1vodn\u00edmi koly - klece z PEEK pro n\u00edzk\u00e9 t\u0159en\u00ed. Otestujte ve sv\u00e9m za\u0159\u00edzen\u00ed: rozto\u010dte je a sledujte teplotu\/vibrace. Profesion\u00e1ln\u00ed rada: vyhn\u011bte se n\u00e1raz\u016fm p\u0159i instalaci; pou\u017e\u00edvejte plastov\u00e9 n\u00e1stroje. \u00dadr\u017eba? Minim\u00e1ln\u00ed - ka\u017edoro\u010dn\u00ed ultrazvuk na praskliny v kritick\u00fdch aplikac\u00edch.<\/p>\n
Budoucnost se to\u010d\u00ed jako div\u00e1. Nano-Si3N4 s grafenem zvy\u0161uje odolnost pro hypersoniku. 3D ti\u0161t\u011bn\u00e9 kuli\u010dky s mikrostrukturou na m\u00edru pro vlastn\u00ed ventily. V kvantov\u00fdch v\u00fdpo\u010dtech jsou v kryopump\u00e1ch. S rozmachem elektromobil\u016f ve va\u0161em okol\u00ed v Los Angeles popt\u00e1vka po nich prudce roste - gigatov\u00e1rny je pot\u0159ebuj\u00ed pro mont\u00e1\u017en\u00ed roboty.<\/p>\n
Z\u00e1v\u011brem, Jacku: kuli\u010dka nitridu k\u0159em\u00edku nen\u00ed ok\u00e1zal\u00e1 vychyt\u00e1vka; je to tich\u00fd profesion\u00e1l, d\u00edky kter\u00e9mu se sv\u011bt to\u010d\u00ed hladce. P\u0159evr\u00e1tily m\u00e9 ne\u00fasp\u011b\u0161n\u00e9 p\u0159\u00edb\u011bhy na \u00fasp\u011b\u0161n\u00e9, od k\u0159i\u010d\u00edc\u00edch turb\u00edn po tich\u00e9 elektromobily. Pokud si pohr\u00e1v\u00e1te s vysokorychlostn\u00edmi p\u0159evody nebo se hon\u00edte za efektivitou, jsou tyto kuli\u010dky va\u0161\u00ed tajnou zbran\u00ed. P\u0159ekonaj\u00ed, p\u0159ed\u010d\u00ed a p\u0159ekonaj\u00ed konkurenci. Zasek\u00e1v\u00e1 se v\u00e1m lo\u017eisko? Napi\u0161te mi specifikace - m\u00e1m opravy i z hor\u0161\u00edch p\u0159\u00edpad\u016f.<\/p>","protected":false},"excerpt":{"rendered":"
Silicon Nitride Balls: The Super-Tough Spheres That Spin Faster, Last Longer, and Defy Extreme Conditions Hey Jack, out there in LA where the only spinning spheres you might think of are the ones in a high-stakes poker game or the wheels on your ride cruising down Sunset Boulevard. But in my neck of the woods\u201440 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[],"class_list":["post-34","post","type-post","status-publish","format-standard","hentry","category-news"],"aioseo_notices":[],"_links":{"self":[{"href":"http:\/\/siliconnitrideballs.net\/cs\/wp-json\/wp\/v2\/posts\/34","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/siliconnitrideballs.net\/cs\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/siliconnitrideballs.net\/cs\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/siliconnitrideballs.net\/cs\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/siliconnitrideballs.net\/cs\/wp-json\/wp\/v2\/comments?post=34"}],"version-history":[{"count":2,"href":"http:\/\/siliconnitrideballs.net\/cs\/wp-json\/wp\/v2\/posts\/34\/revisions"}],"predecessor-version":[{"id":37,"href":"http:\/\/siliconnitrideballs.net\/cs\/wp-json\/wp\/v2\/posts\/34\/revisions\/37"}],"wp:attachment":[{"href":"http:\/\/siliconnitrideballs.net\/cs\/wp-json\/wp\/v2\/media?parent=34"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/siliconnitrideballs.net\/cs\/wp-json\/wp\/v2\/categories?post=34"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/siliconnitrideballs.net\/cs\/wp-json\/wp\/v2\/tags?post=34"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}