{"id":608,"date":"2024-05-23T21:14:15","date_gmt":"2024-05-23T13:14:15","guid":{"rendered":"https:\/\/siliconcarbide.net\/?p=608"},"modified":"2024-05-23T21:19:33","modified_gmt":"2024-05-23T13:19:33","slug":"slinuty-karbid-kremiku-je-supermaterial-ktery-zvladne-temer-cokoli","status":"publish","type":"post","link":"https:\/\/siliconcarbide.net\/cs\/sintered-silicon-carbide-a-super-material-that-can-handle-almost-anything\/","title":{"rendered":"Sp\u00e9kan\u00fd karbid k\u0159em\u00edku - supermateri\u00e1l, kter\u00fd zvl\u00e1dne t\u00e9m\u011b\u0159 cokoli"},"content":{"rendered":"

Sp\u00e9kan\u00fd karbid k\u0159em\u00edku - supermateri\u00e1l, kter\u00fd zvl\u00e1dne t\u00e9m\u011b\u0159 cokoli<\/h1>\n

Dok\u00e1\u017eete si p\u0159edstavit materi\u00e1l, kter\u00fd je t\u00e9m\u011b\u0159 tak tvrd\u00fd jako diamant, plave ve vod\u011b, snese spaluj\u00edc\u00ed \u017e\u00e1r, vysm\u011bje se chemik\u00e1li\u00edm, kter\u00e9 se ho sna\u017e\u00ed se\u017erat, a zachov\u00e1 si pevnost, a\u0165 na n\u011bj hod\u00edte cokoli? Dob\u0159e, slinut\u00fd karbid k\u0159em\u00edku<\/b><\/strong> je ta neuv\u011b\u0159iteln\u00e1 l\u00e1tka!<\/p>\n

Tento materi\u00e1l m\u00e1 tak \u00fa\u017easn\u00e9 vlastnosti, \u017ee zvl\u00e1dne prost\u0159ed\u00ed a podm\u00ednky, kter\u00e9 by zni\u010dily prakticky cokoli jin\u00e9ho, z \u010deho by se dalo n\u011bco vyrobit.<\/p>\n

Pod\u00edvejme se, \u010d\u00edm je slinut\u00fd karbid k\u0159em\u00edku tak v\u00fdjime\u010dn\u00fd.<\/p>\n

Co je slinut\u00fd karbid k\u0159em\u00edku?<\/b><\/strong><\/h2>\n

Sp\u00e9kan\u00fd karbid k\u0159em\u00edku<\/b><\/strong>, zn\u00e1m\u00fd tak\u00e9 jako slinut\u00fd SiC<\/b><\/strong> nebo SSiC<\/b><\/strong>se vyr\u00e1b\u00ed sm\u00edch\u00e1n\u00edm velmi jemn\u00e9ho pr\u00e1\u0161ku SiC s n\u011bkter\u00fdmi speci\u00e1ln\u00edmi p\u0159\u00edsadami, kter\u00e9 pom\u00e1haj\u00ed lepen\u00ed, vlo\u017een\u00edm do formy a va\u0159en\u00edm p\u0159i velmi vysok\u00e9 teplot\u011b. T\u00edm se pr\u00e1\u0161ek spoj\u00ed v pevnou l\u00e1tku, ale \u00fapln\u011b se neroztav\u00ed. Absence jak\u00e9hokoli lepidla nebo dal\u0161\u00edch f\u00e1z\u00ed d\u00e1v\u00e1 slinut\u00e9mu SiC jeho divok\u00e9 vlastnosti.<\/p>\n

Tato keramika m\u00e1 tvrdost<\/b><\/strong> kter\u00fd je druh\u00fd nejlep\u0161\u00ed po diamantu. M\u00e1 n\u00edzk\u00e1 hustota<\/b><\/strong> - kolem 40% jako u oceli a bl\u00ed\u017e\u00ed se hlin\u00edku. Slinut\u00fd SiC<\/b><\/strong> odol\u00e1v\u00e1 koroze<\/b><\/strong> a oxidace<\/b><\/strong> neuv\u011b\u0159iteln\u011b dob\u0159e d\u00edky siln\u00fdm vazb\u00e1m v karbidu k\u0159em\u00edku. Tak\u00e9 dr\u017e\u00ed na sv\u00e9m s\u00edla<\/b><\/strong> a tuhost<\/b><\/strong> i p\u0159i opravdu vysok\u00fdch teplot\u00e1ch, kdy se v\u011bt\u0161ina materi\u00e1l\u016f m\u011bn\u00ed v ka\u0161i.<\/p>\n

Pro\u010d je slinut\u00fd SiC tak v\u00fdjime\u010dn\u00fd?<\/b><\/strong><\/h2>\n

Pod\u00edvejme se na n\u011bkter\u00e9 ohromuj\u00edc\u00ed vlastnosti slinut\u00e9ho SiC a co d\u011bl\u00e1 tuto v\u011bc tak u\u017eite\u010dnou<\/u><\/a>:<\/p>\n

Je to \u0161\u00edlen\u011b t\u011b\u017ek\u00e9<\/b><\/strong><\/p>\n

S Knoopova tvrdost<\/b><\/strong> z 2800 GPa<\/b><\/strong>, slinut\u00fd karbid k\u0159em\u00edku odol\u00e1v\u00e1 po\u0161kr\u00e1b\u00e1n\u00ed nebo jak\u00e9mukoli druhu ot\u011bru l\u00e9pe ne\u017e cokoli jin\u00e9ho krom\u011b diamantu. To znamen\u00e1, \u017ee vydr\u017e\u00ed mnohem d\u00e9le ne\u017e jin\u00e9 materi\u00e1ly p\u0159i pou\u017eit\u00ed, kdy klou\u017ee a je otlouk\u00e1n \u010d\u00e1sticemi.<\/p>\n

Diamond<\/b><\/strong> je jedin\u00e1 t\u011b\u017e\u0161\u00ed v\u011bc. Sm\u011b\u0161n\u00e1 tvrdost SiC poch\u00e1z\u00ed z velmi siln\u00fdch vazeb mezi atomy k\u0159em\u00edku a uhl\u00edku. Tyto vazby pevn\u011b dr\u017e\u00ed a necht\u011bj\u00ed povolit!<\/p>\n

Lehk\u00e9 a p\u0159esto pevn\u00e9<\/b><\/strong><\/p>\n

P\u0159esto\u017ee m\u00e1 nadstandardn\u00ed s\u00edlu, slinut\u00fd SiC m\u00e1 hustotu pouze 3,15 g\/cc<\/b><\/strong>. To se bl\u00ed\u017e\u00ed hlin\u00edku, tak\u017ee je to p\u011bkn\u00e9 a lehk\u00e9!<\/p>\n

To znamen\u00e1, \u017ee d\u00edly vyroben\u00e9 ze slinut\u00e9ho SiC nam\u00edsto kov\u016f mohou b\u00fdt mnohem leh\u010d\u00ed. Rotuj\u00edc\u00ed za\u0159\u00edzen\u00ed se mohou to\u010dit rychleji p\u0159i ni\u017e\u0161\u00ed hmotnosti. A poslechn\u011bte si tohle - SiC skute\u010dn\u011b plave v tekut\u00e9m hlin\u00edku! Je tedy skv\u011bl\u00fd pro sou\u010d\u00e1sti \u010derpadel, kter\u00e9 maj\u00ed co do \u010din\u011bn\u00ed s roztaven\u00fdm kovem.<\/p>\n

Odol\u00e1v\u00e1 korozi a oxidaci jako \u0161ampion<\/b><\/strong><\/p>\n

Kovy pot\u0159ebuj\u00ed ochrannou vrstvu oxidu, aby odolaly korozi. Ale slinut\u00fd SiC<\/b><\/strong> nem\u00e1 \u017e\u00e1dn\u00e9 vazby ani p\u0159\u00eddavn\u00e9 f\u00e1ze, kter\u00e9 by bylo mo\u017en\u00e9 napadnout. Prost\u011b se sm\u011bje korozi v podstat\u011b v jak\u00e9mkoli prost\u0159ed\u00ed, kter\u00e9 na n\u011bj hod\u00edte.<\/p>\n

SiC si zachov\u00e1v\u00e1 pevnost i v oxida\u010dn\u00edm vzduchu a\u017e do 1650 \u00b0C! Jeho odolnost proti korozi a oxidaci je d\u00e1na extr\u00e9mn\u011b siln\u00fdmi vazbami k\u0159em\u00edku a uhl\u00edku. Ty se prost\u011b necht\u011bj\u00ed rozpadnout a oxidovat, pokud nep\u0159ekro\u010d\u00edte super vysok\u00e9 teploty.<\/p>\n

Z\u016fst\u00e1v\u00e1 siln\u00fd i v \u0161\u00edlen\u00fdch vedrech<\/b><\/strong><\/p>\n

Na str\u00e1nk\u00e1ch kovalentn\u00ed vazby<\/b><\/strong> v SiCu zaji\u0161\u0165uj\u00ed jeho tuhost a pevnost i p\u0159i divok\u00fdch teplot\u00e1ch. Slinut\u00fd SiC si zachov\u00e1v\u00e1 svou plnou pevnost<\/b><\/strong> a\u017e do p\u0159ibli\u017en\u011b 1750\u00b0C<\/b><\/strong> - to je \u017ehav\u00e9! Na rozd\u00edl od kov\u016f nesl\u00e1bne ani neopad\u00e1v\u00e1.<\/p>\n

Na str\u00e1nk\u00e1ch vysok\u00fd modul pru\u017enosti<\/b><\/strong> SiC tak\u00e9 znamen\u00e1, \u017ee se p\u0159i velk\u00e9m zat\u00ed\u017een\u00ed pomalu nedeformuje ani neproh\u00fdb\u00e1. M\u016f\u017eete se tedy spolehnout, \u017ee zvl\u00e1dne obrovsk\u00e9 nam\u00e1h\u00e1n\u00ed p\u0159i vysok\u00fdch teplot\u00e1ch. Ide\u00e1ln\u00ed pro d\u00edly do pec\u00ed a pro pou\u017eit\u00ed v letectv\u00ed a kosmonautice!<\/p>\n

Zvl\u00e1d\u00e1 tepeln\u00e9 \u0161oky<\/b><\/strong><\/p>\n

S tepeln\u00e1 vodivost<\/b><\/strong> z 125 W\/mK<\/b><\/strong>, SiC rychle p\u0159en\u00e1\u0161\u00ed tepelnou energii a zvl\u00e1d\u00e1 rychl\u00e9 v\u00fdkyvy teplot. D\u00edky tomu je slinut\u00fd SiC velk\u00e1 odolnost proti teplotn\u00edm \u0161ok\u016fm<\/b><\/strong> ve srovn\u00e1n\u00ed s jinou keramikou.<\/p>\n

N\u00e1hl\u00e9 zm\u011bny teploty mohou zp\u016fsobit, \u017ee k\u0159ehk\u00e9 materi\u00e1ly popraskaj\u00ed v d\u016fsledku nerovnom\u011brn\u00e9 rozta\u017enosti. SiC v\u0161ak neprask\u00e1, proto\u017ee dob\u0159e vede teplo. Bez probl\u00e9m\u016f se p\u0159izp\u016fsob\u00ed teplotn\u00edm v\u00fdkyv\u016fm.<\/p>\n

Vlastnosti slinut\u00e9ho SiC p\u0159i pokojov\u00e9 teplot\u011b<\/b><\/strong><\/p>\n

Zde jsou n\u011bkter\u00e9 kl\u00ed\u010dov\u00e9 statistiky slinut\u00e9ho SiC p\u0159i pokojov\u00e9 teplot\u011b (20 \u00b0C):<\/p>\n