{"id":1857,"date":"2019-05-22T02:48:24","date_gmt":"2019-05-22T02:48:24","guid":{"rendered":"http:\/\/www.meetyoucarbide.com\/single-post-heat-treatment-of-tungsten-carbide-products\/"},"modified":"2020-05-04T13:12:03","modified_gmt":"2020-05-04T13:12:03","slug":"heat-treatment-of-tungsten-carbide-products","status":"publish","type":"post","link":"https:\/\/www.meetyoucarbide.com\/tr\/heat-treatment-of-tungsten-carbide-products\/","title":{"rendered":"Tungsten Karb\u00fcr \u00dcr\u00fcnlerinin Is\u0131l \u0130\u015flemi"},"content":{"rendered":"
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\u00c7imentolu karb\u00fcr (sert metal), y\u00fcksek erime noktal\u0131 metallerden (W, Mo, Ti, V, Ta, vb.) Karb\u00fcrler, nitr\u00fcrler, boridler veya silisitlerden olu\u015fan ala\u015f\u0131mlar i\u00e7in genel bir terimdir. D\u00f6k\u00fcm ve sinterleme olmak \u00fczere iki ana kategoriye ayr\u0131lm\u0131\u015ft\u0131r. D\u00f6kme ala\u015f\u0131m y\u00fcksek k\u0131r\u0131lganl\u0131\u011fa ve d\u00fc\u015f\u00fck toklu\u011fa sahiptir ve pratik uygulama de\u011feri \u00e7ok azd\u0131r. Genellikle tungsten karb\u00fcr veya titanyum karb\u00fcr ve kobalt tozundan sinterlenen ve y\u00fcksek sertlik, a\u015f\u0131nma direnci ve s\u0131cak sertli\u011fe sahip olan sinterlenmi\u015f ala\u015f\u0131mlar yayg\u0131n olarak kullan\u0131lmaktad\u0131r. Esas olarak sert malzemelerin y\u00fcksek h\u0131zl\u0131 kesilmesi ve i\u015flenmesi i\u00e7in kullan\u0131lan, son y\u0131llarda kal\u0131p end\u00fcstrisinde karb\u00fcr kullan\u0131m\u0131 da artmaktad\u0131r, bu nedenle sert ala\u015f\u0131ml\u0131 \u0131s\u0131l i\u015flemi tart\u0131\u015fmak ve incelemek pratik bir \u00f6neme sahiptir.<\/div>\n

1. \u00c7imentolu Karb\u00fcr \u00d6zellikleri<\/h2>\n
Karb\u00fcr, refrakter metal sert bile\u015fikten ve metal ba\u011flama faz\u0131ndan toz metalurjisi y\u00f6ntemi ile yap\u0131l\u0131r. Yayg\u0131n olarak kullan\u0131lan sert bile\u015fikler karb\u00fcrlerdir. Kesici tak\u0131mlar, yayg\u0131n olarak kullan\u0131lan WC, TiC, TaC, NbC, vb.I\u00e7in sert ala\u015f\u0131m olarak ba\u011flay\u0131c\u0131 Co'd\u0131r ve \u00e7imentolu karb\u00fcr\u00fcn g\u00fcc\u00fc esas olarak Co'nun i\u00e7eri\u011fine ba\u011fl\u0131d\u0131r. \u00c7\u00fcnk\u00fc \u00e7imentolu karb\u00fcrdeki karb\u00fcr bir y\u00fcksek erime noktas\u0131 (3140 \u00b0 C Ti C'nin erime noktas\u0131), y\u00fcksek sertlik (3200 HV TiC sertli\u011fi gibi), iyi bir kimyasal kararl\u0131l\u0131k ve iyi bir termal kararl\u0131l\u0131k, sertlik ve a\u015f\u0131nma direnci y\u00fcksek. Cinsiyet ve kimyasal kararl\u0131l\u0131k, y\u00fcksek h\u0131zl\u0131 tak\u0131m \u00e7eliklerinden \u00e7ok daha y\u00fcksektir.<\/div>\n
Yayg\u0131n olarak kullan\u0131lan \u00e7imentolu karb\u00fcr sert faz esas olarak iyi a\u015f\u0131nma direncine sahip WC'dir. Baz\u0131 karb\u00fcrler WC ile benzer sertli\u011fe sahip olsalar da, ayn\u0131 a\u015f\u0131nma direncine sahip de\u011fildirler. WC daha y\u00fcksek akma dayan\u0131m\u0131na (6000 MPa) sahiptir, bu nedenle plastik deformasyona daha dayan\u0131kl\u0131d\u0131r. WC'nin \u0131s\u0131 iletkenli\u011fi de iyidir ve termal iletkenlik, tak\u0131m\u0131n \u00f6nemli bir performans endeksidir. WC, \u00e7eli\u011fin yakla\u015f\u0131k 1 \/ 3'\u00fc kadar daha d\u00fc\u015f\u00fck bir termal genle\u015fme katsay\u0131s\u0131na sahiptir; esneklik mod\u00fcl\u00fc \u00e7elikten 3 kat daha fazlad\u0131r ve bas\u0131n\u00e7 dayan\u0131m\u0131 da \u00e7elikten daha y\u00fcksektir. Buna ek olarak, WC'nin oda s\u0131cakl\u0131\u011f\u0131nda korozyon ve oksidasyona kar\u015f\u0131 iyi direnci, iyi elektrik direnci ve y\u00fcksek e\u011filme mukavemeti vard\u0131r.<\/div>\n

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\u015eekil 1 WC-Co ala\u015f\u0131m\u0131n\u0131n yar\u0131 denge diyagram\u0131<\/div>\n

2. \u0131s\u0131l i\u015flem ve ala\u015f\u0131m organizasyonu<\/h2>\n
Farkl\u0131 C \/ W oranlar\u0131 5% ila 35% WC olan WC-Co ala\u015f\u0131mlar\u0131n\u0131n ba\u011flanma a\u015famalar\u0131 \u00fczerinde \u00e7al\u0131\u015f\u0131lm\u0131\u015ft\u0131r. Sonu\u00e7lar a\u015fa\u011f\u0131daki gibi elde edilir: cooling-fazl\u0131 veya (\u03b3 + WC) fazlar yava\u015f so\u011futmada ala\u015f\u0131mda \u00fcretilir; (\u0393 + \u03b7) fazlar\u0131 oldu\u011funda. Bununla birlikte, (\u03b3 + \u03b7) faz\u0131 karars\u0131z oldu\u011fundan, (\u03b3 + \u03b7) faz\u0131 tavlamadan sonra kararl\u0131 (\u03b3 + WC) faza d\u00f6n\u00fc\u015fecektir. Test sonu\u00e7lar\u0131na g\u00f6re, \u015eekil l'de g\u00f6sterilen yar\u0131 denge faz diyagram\u0131 \u00e7izilir (d\u00fcz \u00e7izgi kararl\u0131 sistemin faz diyagram\u0131d\u0131r ve kesik \u00e7izgi yar\u0131 kararl\u0131l\u0131\u011f\u0131n \u03b7 \u00f6zelliklerini g\u00f6steren yerel faz diyagram\u0131d\u0131r evre).<\/div>\n
Tipik semente karb\u00fcr\u00fcn tavlanmas\u0131 (yava\u015f so\u011fuma) esas olarak karbon i\u00e7eri\u011fine ba\u011fl\u0131d\u0131r: C \/ W> 1 oldu\u011funda, serbest karbon WC-Co faz s\u0131n\u0131r\u0131nda \u00e7\u00f6kelir; C \/ W <1 oldu\u011funda, ala\u015f\u0131m\u0131n mikroyap\u0131s\u0131 her iki durumda da: Biri \u00fc\u00e7 fazl\u0131 b\u00f6lgededir (WC + \u03b3 + \u03b7). \u0397 faz\u0131n\u0131n ala\u015f\u0131m yava\u015f\u00e7a so\u011futulduktan sonra ortaya \u00e7\u0131kmas\u0131 ka\u00e7\u0131n\u0131lmazd\u0131r. \u00c7imentolu fazda bu kadar b\u00fcy\u00fck miktarda \u03b7 faz\u0131 varsa, dall\u0131 kristal taneler ortaya \u00e7\u0131kar ve k\u00fc\u00e7\u00fck taneler d\u00fczensiz da\u011f\u0131t\u0131l\u0131r; \u03b7 faz\u0131n\u0131n b\u00fcy\u00fck bir tane varsa, taneler uzun bir mesafe ile ayr\u0131l\u0131r, bu nedenle \u03b7 faz\u0131n\u0131n daha y\u00fcksek s\u0131cakl\u0131klar olu\u015fmaya ba\u015flad\u0131\u011f\u0131 bilgisi vard\u0131r.<\/div>\n
Di\u011fer durumda, ala\u015f\u0131m iki fazl\u0131 (WC + y) b\u00f6lgesinde oldu\u011funda, d\u00fc\u015f\u00fck karbonlu ala\u015f\u0131m tavland\u0131ktan sonra W ala\u015f\u0131m\u0131 ba\u011flama faz\u0131ndan Co3W olarak \u00e7\u00f6kt\u00fcr\u00fclecektir. Reaksiyon i\u015flemi, a\u015fa\u011f\u0131daki form\u00fcl ile ifade edilebilir. Co Y\u00fcz merkezli k\u00fcbik \u2192 Co Y\u00fcz merkezli k\u00fcbik + Co3W Bu nedenle, bu d\u00fc\u015f\u00fck karbonlu iki fazl\u0131 WC-Co ala\u015f\u0131m\u0131 tavlamadan sonra \u00fc\u00e7 fazl\u0131 (WC + \u03b3 + CoW) bir yap\u0131ya d\u00f6n\u00fc\u015ft\u00fcr\u00fclecektir. \u015eekil 2, farkl\u0131 tavlama s\u0131cakl\u0131klar\u0131nda iki fazl\u0131 WC-Co ala\u015f\u0131mlar\u0131 i\u00e7in W'nin \u00e7\u00f6z\u00fcnme e\u011frilerini g\u00f6stermektedir. E\u011fri, \u00fc\u00e7 fazl\u0131 (WC + \u03b3 + CoW) ala\u015f\u0131mlara d\u00f6n\u00fc\u015ft\u00fcr\u00fclm\u00fc\u015f iki fazl\u0131 ala\u015f\u0131mlar i\u00e7in kritik s\u0131cakl\u0131k e\u011frisidir: e\u011fri s\u0131cakl\u0131\u011f\u0131n\u0131n \u00fcst\u00fcnde Tavlama iki fazl\u0131 bir mikroyap\u0131 ala\u015f\u0131m\u0131yla sonu\u00e7lan\u0131r; e\u011frinin alt\u0131ndaki s\u0131cakl\u0131klarda tavlama Co3W i\u00e7eren \u00fc\u00e7 fazl\u0131 bir yap\u0131 verir.<\/div>\n

3. Is\u0131l i\u015flem s\u00fcrecinin sertlik ala\u015f\u0131m\u0131n\u0131n mekanik \u00f6zelliklerine etkisi<\/h2>\n
(1) Mukavemet \u00dczerine Etkisi WC, Co'daki farkl\u0131 s\u0131cakl\u0131klarda farkl\u0131 kat\u0131 \u00e7\u00f6z\u00fcn\u00fcrl\u00fc\u011fe sahip oldu\u011fundan, kat\u0131 faz s\u0131cakl\u0131\u011f\u0131 s\u00f6nd\u00fcrme ve m\u00fcteakip ya\u015fland\u0131rma ile ba\u011flay\u0131c\u0131 faz\u0131n \u00e7\u00f6kelme sertle\u015fmesi olas\u0131l\u0131\u011f\u0131n\u0131 sa\u011flar. S\u00f6nd\u00fcrme, WC'nin \u00e7\u00f6kelmesini ve Co'nun (Co yo\u011fun alt\u0131gen, Co y\u00fcz merkezli k\u00fcbik) homotropi ge\u00e7i\u015fini inhibe edebilir. 40% kobalt i\u00e7eren ala\u015f\u0131m\u0131n mukavemetinin, s\u00f6nd\u00fcrme i\u015fleminden sonra yakla\u015f\u0131k 10% artt\u0131r\u0131labilece\u011fi, ancak s\u00f6nd\u00fcrme i\u015fleminden sonra 10% kobalt i\u00e7eren ala\u015f\u0131m\u0131n mukavemetinin azald\u0131\u011f\u0131 bildirilmi\u015ftir. M\u00fchendislikte yayg\u0131n olarak kullan\u0131lan \u00e7imentolu karb\u00fcrlerde bulunan kobalt miktar\u0131n\u0131n genellikle 10% ila 37% oldu\u011fu d\u00fc\u015f\u00fcn\u00fcld\u00fc\u011f\u00fcnde, \u0131s\u0131l i\u015flemin ala\u015f\u0131m mukavemeti \u00fczerindeki etkisi \u00e7ok azd\u0131r. Bu y\u00fczden birisi, s\u00f6nd\u00fcrmenin W-Co ala\u015f\u0131mlar\u0131 i\u00e7in g\u00fcc\u00fc artt\u0131rman\u0131n bir yolu olmad\u0131\u011f\u0131n\u0131 iddia etmeye cesaret etti. Tavlama ayr\u0131ca Tablo 1 ve 3'te g\u00f6sterildi\u011fi gibi ala\u015f\u0131m\u0131n mukavemetinde bir azalmaya neden olur. Tungsten karb\u00fcr\u00fcn \u00f6zellikleri, \u015eekil 4'te g\u00f6sterildi\u011fi gibi i\u00e7erilen Co miktar\u0131na ve tanelerin kal\u0131nl\u0131\u011f\u0131na g\u00f6re de\u011fi\u015fir.<\/div>\n

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\u015eekil 2 WC-10%Co iki fazl\u0131 ala\u015f\u0131mdaki tungstenin kat\u0131 \u00e7\u00f6z\u00fcn\u00fcrl\u00fck e\u011frisi<\/div>\n

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\u015eekil 3 800 \u00b0 C'de tavlaman\u0131n WC-10%Co i\u00e7eri\u011finin e\u011filme dayan\u0131m\u0131 \u00fczerindeki etkisi<\/div>\n