기계화학적방법에 의한 나노구조 WC/Co 복합 분말의 제조에 관한 연구
A Study On Synthesis of Nanostructured WC/Co composite Powders by Mechanochemical process
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Abstract
A new approach to produce nanostructured WC/Co composite powders by a mechanochemical process was made to improve the mechanical properties of advanced hardmetals. Homogeneous spherical W-Co salt powders were made by spray drying of aqueous solution from ammonium metatungstate((NH4)6(H2W12O40) 4H2O, AMT) and cobalt nitrate hexahydrate(Co(NO3)2 6H2O). Spray dried W-Co salt powders were calcined for 1 hr at 700℃ in atmosphere of air. The oxide powder was mixed with carbon black by ball milling and this mixture was heated with various temperatures and times in H2. The WO3/CoWO4 composite oxide powders were obtained by calcination at 700℃. The primary particle size of W/Co composite oxide powders by SEM was 100 nm. The reduction/carburization time decreased with increasing temperatures and carbon additions. The average size of WC particle carburized at 800℃ by TEM was smaller than 50 nm.