![\"korundov\u00e1](\"https:\/\/aluminaceramics.net\/wp-content\/uploads\/2024\/06\/alumina-ceramics.jpg\")
<\/p>","protected":false},"excerpt":{"rendered":"Hlin\u00edk je velmi obl\u00edben\u00e1 technick\u00e1 keramika, kter\u00e1 krom\u011b chemick\u00e9 stability a vysok\u00e9 pevnosti v ohybu nab\u00edz\u00ed vynikaj\u00edc\u00ed tepelnou odolnost a n\u00edzk\u00fd bod t\u00e1n\u00ed.<\/p>\n
Zkou\u0161ky ohybem umo\u017e\u0148uj\u00ed p\u0159esn\u00e9 m\u011b\u0159en\u00ed elastick\u00fdch vlastnost\u00ed oxidu hlinit\u00e9ho pomoc\u00ed t\u0159\u00edbodov\u00fdch a \u010dty\u0159bodov\u00fdch zkou\u0161ek ohybem.<\/p>\n
Pru\u017enost oxidu hlinit\u00e9ho p\u0159\u00edmo souvis\u00ed s jeho mez\u00ed kluzu; s klesaj\u00edc\u00edm modulem pru\u017enosti roste i jeho mez kluzu.<\/p>\n
Young\u016fv modul je vlastnost materi\u00e1lu, kter\u00e1 m\u011b\u0159\u00ed, jak snadno se materi\u00e1ly oh\u00fdbaj\u00ed nebo deformuj\u00ed p\u016fsoben\u00edm siln\u00fdch protich\u016fdn\u00fdch vliv\u016f, p\u0159i\u010dem\u017e vy\u0161\u0161\u00ed Young\u016fv modul p\u0159edstavuje pru\u017en\u011bj\u0161\u00ed materi\u00e1ly, jako je nap\u0159\u00edklad oxid hlinit\u00fd. Hlin\u00edk m\u00e1 obzvl\u00e1\u0161t\u011b vysokou hodnotu Youngova modulu, jak dokl\u00e1d\u00e1 tabulka 1.<\/p>\n
Young\u016fv modul je pro in\u017een\u00fdry z\u00e1sadn\u00ed \u00fadaj, proto\u017ee ud\u00e1v\u00e1, jak velk\u00e1 s\u00edla je nutn\u00e1 k rozta\u017een\u00ed materi\u00e1lu. Nap\u0159\u00edklad k rozta\u017een\u00ed hlin\u00edku je zapot\u0159eb\u00ed p\u0159ibli\u017en\u011b t\u0159ikr\u00e1t v\u011bt\u0161\u00ed s\u00edla ne\u017e k rozta\u017een\u00ed oceli - tato znalost umo\u017e\u0148uje in\u017een\u00fdr\u016fm navrhovat bezpe\u010dn\u00e9 a pevn\u00e9 konstrukce.<\/p>\n
Young\u016fv modul m\u016f\u017ee tak\u00e9 pomoci ur\u010dit, jak se materi\u00e1ly chovaj\u00ed v r\u016fzn\u00fdch prost\u0159ed\u00edch. Nap\u0159\u00edklad oxid hlinit\u00fd m\u00e1 p\u0159i pokojov\u00e9 teplot\u011b extr\u00e9mn\u011b vysok\u00fd Young\u016fv modul; s rostouc\u00edm tlakem a teplotou v\u0161ak kles\u00e1, proto\u017ee v\u011bt\u0161\u00ed vibra\u010dn\u00ed energie umo\u017e\u0148uje jednotliv\u00fdm atom\u016fm snadn\u011bji se odd\u011blit, \u010d\u00edm\u017e se vazby mezi atomy st\u00e1vaj\u00ed m\u00e9n\u011b pevn\u00fdmi.<\/p>\n
Young\u016fv modul lze pou\u017e\u00edt k p\u0159edpov\u011bdi chov\u00e1n\u00ed materi\u00e1lu za r\u016fzn\u00fdch podm\u00ednek, v\u010detn\u011b reakce ve vodn\u00edm prost\u0159ed\u00ed. Hooke\u016fv z\u00e1kon nav\u00edc nab\u00edz\u00ed dal\u0161\u00ed matematick\u00fd v\u00fdpo\u010det zn\u00e1m\u00fd jako Young\u016fv modul, kter\u00fd m\u016f\u017ee pomoci ur\u010dit jeho nap\u011b\u0165ov\u011b-deforma\u010dn\u00ed vlastnosti materi\u00e1l\u016f.<\/p>\n
Young\u016fv modul pro jak\u00fdkoli materi\u00e1l se ur\u010duje pomoc\u00ed rovnice: Young\u016fv modul = nap\u011bt\u00ed (s\u00edla na jednotku plochy)\/deformace (pom\u011brn\u00e1 deformace materi\u00e1lu). Proto je nezbytn\u00e9 zn\u00e1t hodnoty dynamick\u00e9ho i statick\u00e9ho Youngova modulu pro dan\u00fd vzorek - \u010dasto z\u00edskan\u00e9 laboratorn\u00edmi zkou\u0161kami v j\u00e1d\u0159e, nap\u0159\u00edklad jednoosou tlakovou zkou\u0161kou - a teprve pot\u00e9 porovnat tyto hodnoty s teoretick\u00fdmi rovnicemi, aby se zajistila jejich shoda.<\/p>\n
Aby bylo mo\u017en\u00e9 p\u0159esn\u011b ur\u010dit dynamick\u00fd Young\u016fv modul jak\u00e9hokoli materi\u00e1lu, mus\u00ed b\u00fdt jeho rozm\u011bry a plocha pr\u016f\u0159ezu co nejp\u0159esn\u011bj\u0161\u00ed. Pokud tuto p\u0159esnost nelze dodr\u017eet, pak t\u00edm utrp\u00ed i jeho souvisej\u00edc\u00ed dynamick\u00fd Young\u016fv modul. Je velmi d\u016fle\u017eit\u00e9, aby m\u011b\u0159en\u00ed prob\u00edhala ve v\u00edce bodech, aby se vytvo\u0159ila p\u0159esn\u00e1 z\u00e1kladn\u00ed linie, a aby m\u011b\u0159en\u00ed byla prov\u00e1d\u011bna co nejp\u0159esn\u011bji - jinak budou hodnoty dynamick\u00e9ho Youngova modulu rovn\u011b\u017e nep\u0159esn\u00e9 v d\u016fsledku nep\u0159esn\u00fdch rozm\u011br\u016f vzork\u016f materi\u00e1lu.<\/p>\n
Modul pru\u017enosti ve smyku m\u011b\u0159\u00ed pom\u011br mezi smykov\u00fdm nap\u011bt\u00edm a deformac\u00ed v materi\u00e1lu, kter\u00fd se tak\u00e9 ozna\u010duje jako modul tuhosti nebo modul pru\u017enosti ve smyku a umo\u017e\u0148uje posoudit, jak jsou materi\u00e1ly odoln\u00e9 v\u016f\u010di smykov\u00e9 deformaci. Spolu s Youngov\u00fdm modulem a Poissonov\u00fdm pom\u011brem n\u00e1m smykov\u00fd modul umo\u017e\u0148uje zjistit jeho elastick\u00e9 vlastnosti.<\/p>\n
Modul pru\u017enosti ve smyku je p\u0159evr\u00e1cenou hodnotou Youngova modulu a Poissonova pom\u011bru, a proto umo\u017e\u0148uje snadn\u00e9 porovn\u00e1n\u00ed materi\u00e1l\u016f. Diamant se m\u016f\u017ee pochlubit v\u00fdjime\u010dn\u00fdm modulem pru\u017enosti ve smyku d\u00edky kompaktn\u00ed m\u0159\u00ed\u017ece atom\u016f uhl\u00edku, co\u017e vede k jeho v\u00fdjime\u010dn\u00e9 tvrdosti. Ocel m\u00e1 ve srovn\u00e1n\u00ed s diamantem p\u0159ibli\u017en\u011b desetkr\u00e1t ni\u017e\u0161\u00ed hodnotu modulu pru\u017enosti ve smyku.<\/p>\n
Na rozd\u00edl od tahov\u00e9ho nebo tlakov\u00e9ho nap\u011bt\u00ed, kter\u00e9 p\u016fsob\u00ed rovnom\u011brn\u011b po cel\u00e9 plo\u0161e, smykov\u00e9 nap\u011bt\u00ed deformuje p\u0159edm\u011bty do rovnob\u011b\u017en\u00edk\u016f. Krom\u011b toho obvykle p\u016fsob\u00ed pouze na jednu stranu materi\u00e1lu, zat\u00edmco tahov\u00e1\/kompresn\u00ed nap\u011bt\u00ed \u010dasto p\u016fsob\u00ed na v\u0161echny strany. Smykov\u00e9 nap\u011bt\u00ed je jin\u00fd term\u00edn pro tuto formu deforma\u010dn\u00edho nap\u011bt\u00ed vyvolan\u00e9ho silou p\u016fsob\u00edc\u00ed kolmo pod\u00e9l povrchu materi\u00e1lu; smykov\u00e9 nap\u011bt\u00ed m\u00e1 mnoho variant, kter\u00e9 se zna\u010dn\u011b li\u0161\u00ed.<\/p>\n
Modul pru\u017enosti ve smyku materi\u00e1l\u016f lze vypo\u010d\u00edtat podle vzorce E=m2\/G, kde E je smykov\u00e9 nap\u011bt\u00ed, m je hustota materi\u00e1lu a G p\u0159edstavuje smykovou deformaci. Stejn\u00fd vzorec lze pou\u017e\u00edt tak\u00e9 k v\u00fdpo\u010dtu Youngova modulu a Poissonova pom\u011bru.<\/p>\n
Smykov\u00e9 moduly se \u010dasto vyjad\u0159uj\u00ed v gigapascalech (GPa), co\u017e jsou stejn\u00e9 jednotky, kter\u00e9 se pou\u017e\u00edvaj\u00ed pro m\u011b\u0159en\u00ed tlaku. D\u00edky tomu je uv\u00e1d\u011bn\u00ed jejich ekvivalent\u016f v pascalech nebo psi jednodu\u0161\u0161\u00ed, ne\u017e by jejich pou\u017eit\u00ed vy\u017eadovalo v\u011bdeck\u00fd z\u00e1pis.<\/p>\n
Modul pru\u017enosti ve smyku je \u00fa\u010dinn\u00fdm m\u011b\u0159\u00edtkem odolnosti materi\u00e1lu proti smykov\u00e9 deformaci a m\u016f\u017ee in\u017een\u00fdr\u016fm pomoci p\u0159i navrhov\u00e1n\u00ed odoln\u011bj\u0161\u00edch d\u00edl\u016f pro aplikace. Obra\u0165te se na spole\u010dnost Xometry je\u0161t\u011b dnes a z\u00edskejte v\u00edce informac\u00ed o na\u0161ich mo\u017enostech v oblasti in\u017een\u00fdrstv\u00ed, v\u00fdroby prototyp\u016f a slu\u017eeb s p\u0159idanou hodnotou, jako\u017e i o dostupn\u00fdch slu\u017eb\u00e1ch s p\u0159idanou hodnotou - r\u00e1di v\u00e1m pom\u016f\u017eeme se v\u0161emi va\u0161imi pot\u0159ebami v oblasti zak\u00e1zkov\u00e9 v\u00fdroby - z\u00edskejte nab\u00eddku online hned te\u010f!<\/p>\n
Poisson\u016fv pom\u011br je materi\u00e1lov\u00e1 vlastnost, kter\u00e1 m\u011b\u0159\u00ed, jak velk\u00e9mu nam\u00e1h\u00e1n\u00ed je materi\u00e1l vystaven v dan\u00e9m sm\u011bru. Tuto vlastnost vypo\u010d\u00edt\u00e1me jednodu\u0161e tak, \u017ee p\u0159\u00ed\u010dnou deformaci (e_trans) vyd\u011bl\u00edme axi\u00e1ln\u00ed deformaci (e_axial). Kladn\u00e1 hodnota znamen\u00e1 rozp\u00edn\u00e1n\u00ed, zat\u00edmco z\u00e1porn\u00e1 hodnota znamen\u00e1 smr\u0161\u0165ov\u00e1n\u00ed - m\u016f\u017eete ji vypo\u010d\u00edtat podle vzorce n = (-e_trans)\/(e_axial).<\/p>\n
Poisson\u016fv pom\u011br m\u011b\u0159\u00ed geometrii a tvar meziatomov\u00fdch vazeb v materi\u00e1lu. V ide\u00e1ln\u00edm p\u0159\u00edpad\u011b by tato hodnota m\u011bla b\u00fdt kladn\u00e1 a pohybovat se v rozmez\u00ed od nuly do 0,5, aby byla zaji\u0161t\u011bna optim\u00e1ln\u00ed odolnost proti prota\u017een\u00ed. Materi\u00e1ly s kladn\u00fdm Poissonov\u00fdm pom\u011brem maj\u00ed p\u0159i natahov\u00e1n\u00ed tendenci odol\u00e1vat objemov\u00fdm zm\u011bn\u00e1m snadn\u011bji ne\u017e zm\u011bn\u00e1m tvaru.<\/p>\n
Poisson\u016fv pom\u011br, podobn\u011b jako Young\u016fv modul, hraje ned\u00edlnou roli p\u0159i ur\u010dov\u00e1n\u00ed pevnosti a tuhosti materi\u00e1lu. In\u017een\u00fd\u0159i vyu\u017e\u00edvaj\u00ed jeho modul pru\u017enosti p\u0159i navrhov\u00e1n\u00ed konstrukc\u00ed, kter\u00e9 jsou schopny odolat velk\u00fdm sil\u00e1m, ani\u017e by se rozpadly nebo trvale deformovaly.<\/p>\n
Poisson\u016fv pom\u011br lze m\u011bnit v z\u00e1vislosti na slo\u017een\u00ed i prost\u0159ed\u00ed, nap\u0159\u00edklad zm\u011bnou teploty nebo tlaku. Pomoci m\u016f\u017ee tak\u00e9 zm\u011bna geometrie (nap\u0159\u00edklad vytvo\u0159en\u00ed p\u011bnov\u00fdch nebo vo\u0161tinov\u00fdch materi\u00e1l\u016f s r\u016fznou strukturou bun\u011bk).<\/p>\n
Jednou z metod m\u011b\u0159en\u00ed pru\u017enosti materi\u00e1l\u016f je m\u011b\u0159en\u00ed jejich hystereze. Hystereze m\u011b\u0159\u00ed mechanickou energii rozpt\u00fdlenou b\u011bhem cykl\u016f smyku a stla\u010den\u00ed, co\u017e je u\u017eite\u010dn\u00e9 p\u0159i hodnocen\u00ed elastick\u00fdch vlastnost\u00ed a tak\u00e9 p\u0159i odhalov\u00e1n\u00ed defekt\u016f v materi\u00e1lech.<\/p>\n
Hysterezi materi\u00e1l\u016f lze ur\u010dit m\u011b\u0159en\u00edm doby, za kterou jimi projdou smykov\u00e9 vlny; jednou z metod je ultrazvukov\u00e9 za\u0159\u00edzen\u00ed, kter\u00e9 vys\u00edl\u00e1 pod\u00e9ln\u00e9 i smykov\u00e9 vlny sou\u010dasn\u011b. Krom\u011b toho m\u016f\u017ee do t\u00e9to problematiky nahl\u00e9dnout i skenovac\u00ed elektronov\u00e1 mikroskopie.<\/p>\n
Hustota je m\u011b\u0159\u00edtkem toho, kolik hmoty se vejde do ur\u010dit\u00e9ho objemu, neboli hmotnost d\u011blen\u00e1 objemem, a je to velmi u\u017eite\u010dn\u00e1 fyzik\u00e1ln\u00ed vlastnost, kter\u00e1 n\u00e1m umo\u017e\u0148uje pochopit, jak r\u016fzn\u00e9 materi\u00e1ly reaguj\u00ed p\u0159i nam\u00e1h\u00e1n\u00ed.<\/p>\n
Hustota umo\u017e\u0148uje pochopit r\u016fzn\u00e9 zaj\u00edmav\u00e9 jevy, nap\u0159\u00edklad pro\u010d mohou velk\u00e9 kovov\u00e9 lod\u011b plavat a pro\u010d se olej a ocet po spojen\u00ed rozd\u011bl\u00ed na vrstvy. Archimedes pou\u017eil hustotu, aby uk\u00e1zal, jak \u0159emesln\u00edk podvedl kr\u00e1le Agrippu, kdy\u017e nahradil zlat\u00e9 koruny st\u0159\u00edbrn\u00fdmi; hustota tak\u00e9 vysv\u011btluje, pro\u010d maj\u00ed m\u011bd\u011bn\u00e9 krychle stejn\u00e9 velikosti v\u011bt\u0161\u00ed hmotnost ne\u017e jejich hlin\u00edkov\u00e9 prot\u011bj\u0161ky, p\u0159esto\u017ee ob\u011b nemaj\u00ed \u017e\u00e1dn\u00e9 dut\u00e9 prostory.<\/p>\n
Pochopen\u00ed hustoty materi\u00e1l\u016f je z\u00e1sadn\u00ed pro v\u011bdeck\u00e9, technick\u00e9 a technologick\u00e9 v\u00fdpo\u010dty. Znalost hustoty poskytuje informace pot\u0159ebn\u00e9 k v\u00fdpo\u010dtu pot\u0159ebn\u00fdch sil pro plastickou deformaci, kter\u00e9 se \u010dasto pou\u017e\u00edvaj\u00ed p\u0159i anal\u00fdze kone\u010dn\u00fdch prvk\u016f (MKP). Hustotu lze vypo\u010d\u00edtat podle tohoto vzorce: (m\/v), kde m je hmotnost, v je objem a g p\u0159edstavuje gravita\u010dn\u00ed zrychlen\u00ed za jednotku \u010dasu - obvykle je definov\u00e1no jako 1 kg\/cm3.<\/p>\n
Hlin\u00edk vynik\u00e1 mezi technickou keramikou na b\u00e1zi oxid\u016f vysokou hustotou a \u0161irokou \u0161k\u00e1lou u\u017eite\u010dn\u00fdch vlastnost\u00ed, jako je mechanick\u00e1 pevnost, tvrdost, odolnost proti ot\u011bru a korozi\/opot\u0159eben\u00ed. Krom\u011b toho se oxid hlinit\u00fd m\u016f\u017ee pochlubit st\u0159edn\u00ed tepelnou vodivost\u00ed a n\u00edzk\u00fdmi hodnotami tepeln\u00e9 kapacity a tak\u00e9 snadnou v\u00fdrobou do nestandardn\u00edch tvar\u016f a velikost\u00ed.<\/p>\n
Modul pru\u017enosti hlin\u00edku je p\u0159\u00edmo \u00fam\u011brn\u00fd jeho hustot\u011b; nap\u0159\u00edklad ocel s t\u0159ikr\u00e1t v\u011bt\u0161\u00edm modulem pru\u017enosti bude m\u00edt o t\u0159etinu v\u011bt\u0161\u00ed zp\u011btn\u00fd r\u00e1z. P\u0159edpov\u011bdi jeho modulu pru\u017enosti lze prov\u00e9st pomoc\u00ed t\u0159\u00edbodov\u00fdch a \u010dty\u0159bodov\u00fdch ohybov\u00fdch zkou\u0161ek nebo proveden\u00edm simulace materi\u00e1lu metodou kone\u010dn\u00fdch prvk\u016f a n\u00e1sledn\u00fdm porovn\u00e1n\u00edm v\u00fdsledk\u016f simulace se skute\u010dn\u00fdmi experiment\u00e1ln\u00edmi \u00fadaji pro \u00fa\u010dely ov\u011b\u0159en\u00ed. Hustom\u011bry vyu\u017e\u00edvaj\u00ed laserovou technologii k p\u0159\u00edm\u00e9mu m\u011b\u0159en\u00ed tlaku p\u016fsob\u00edc\u00edho na povrch vzorku.<\/p>\n
<\/p>","protected":false},"excerpt":{"rendered":"
Alumina is an extremely popular engineering ceramic that offers excellent thermal resistance and low melting point properties, in addition to […]<\/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":""}},"footnotes":""},"categories":[6],"tags":[],"class_list":["post-137","post","type-post","status-publish","format-standard","hentry","category-alumina-knowledge"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/aluminaceramics.net\/cs\/wp-json\/wp\/v2\/posts\/137","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/aluminaceramics.net\/cs\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/aluminaceramics.net\/cs\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/aluminaceramics.net\/cs\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/aluminaceramics.net\/cs\/wp-json\/wp\/v2\/comments?post=137"}],"version-history":[{"count":4,"href":"https:\/\/aluminaceramics.net\/cs\/wp-json\/wp\/v2\/posts\/137\/revisions"}],"predecessor-version":[{"id":154,"href":"https:\/\/aluminaceramics.net\/cs\/wp-json\/wp\/v2\/posts\/137\/revisions\/154"}],"wp:attachment":[{"href":"https:\/\/aluminaceramics.net\/cs\/wp-json\/wp\/v2\/media?parent=137"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/aluminaceramics.net\/cs\/wp-json\/wp\/v2\/categories?post=137"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/aluminaceramics.net\/cs\/wp-json\/wp\/v2\/tags?post=137"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}