Document Type : Original Reaearch Article

Authors

K. N. Toosi University of Technology, Faculty of Materials Science and Engineering, Tehran, Iran

Abstract

Tungsten carbides are used in cutting blades and other similar items because of their high hardness. In this study, tungsten carbide (WC) powder and cobalt (Co) powder in size of less than 10 microns and weight ratio of 94% tungsten carbide and 6% cobalt (WC-6% Co) were mixed together in a high-energy mechanical milling. Then they milled in various ratios of ball to powder and time. Milled samples were studied using scanning electron microscopy (SEM). The results obtained were compared by microscopy and EDX elemental analysis. Optimized powder for the production of powder metallurgy sample was selected and sintered. Metallography and hardness testing and SEM imaging was performed on sintered sample. The results showed a significant improvement in grain size to reach below 100 nm in the milled powders and in the sintered samples were reaching below 150 nm. Vickers hardness in the final sample reached in 1752.

Keywords

1- Suryanarayana C, Mechanical alloying and milling, Prog Mater Sci, 2001, 46(1), 180–184.
2- Sherif El-Eskandarany M, Mahday A, Synthesis and Characterization of ball-milled nanocrystalline WC and nanocomposite WC–Co Powders and subsequent consolidation, J Alloy Comp 2000, 312, 315–325.
3- Mahmoodan M, aliakbarzadeh H, gholamipour R. M, Microstructural and mechanical characterizations of high energy ball milled and sintered WC-10wt% Co-xTaC nanocomposite powders [J]. Int J Ref Met Mat, 2009, 27(4), 801-805.
4- Kumar A, Sintering behavior of nanostructured WC–Co composite, Ceramics International, 2011, 37, 1415–1422.
5- Enayati M.H, Aryanpour G.R, Ebnonnasi A, Production of nanostructured WC–Co powder by ball milling, Int J Refract Met Hard Mater, 2009, 27, 159–63.
6- Zhang FL, Zhu M, Wang CY, Parameters optimization in the planetary ball milling Of nanostructured tungsten carbide/cobalt powder, International Journal of Refractory Metals & Hard Materials, 26, 2008, 329–333
7- Suryanarayana C, The science and technology of mechanical alloying, Materials Science and Engineering, 2000, 151–158.
8- Sun J, Characterizations of ball-milled nanocrystalline WC–Co composite powders and subsequently rapid hot pressing sintered, cermet Materials Letters, 2003, 57, 3140–3148.
9- Zhang FL, Wang CY, Zhu M. Nanostructured WC/Co composite Powder prepared by high energy ball milling, Scripta Mater, 2003, 49(11),1123–1128.
10- Williamson G.K, Hall W.H, X-ray line broadening from filed aluminum and wolfram, Acta Metall, 1953, 1, 22–31.
11- Kim H.C, Oh D.Y, Shon I.J, Sintering of nanophase WC–15vol.%Co Hard metals by rapid sintering process, Int J Refract Met Hard Mater, 2004, 22, 197–203.
12- Allibert CH, Sintering features of cemented carbides WC-Co processed from fine powders, Int J Ref Met Hard Mat, 2001, 19, 53-61.
13- Mahmoodan M, Sintering of WC-10%Co nano powders containing TaC and VC grain growth inhibitors, Nonferrous Met, 2011, 21, 1080-1084.
14- Fang ZZ, Development of Bulk Nanocrystalline Cemented Tungsten Carbide for Industrial Applications, Technical Report to the U. S. Department of Energy, 2009.