The role of the binder phase in the WC-Co sintering

Abstract

The sintering of hardmetal in the solid state is studied. The influence of the WC particle size on the sintering kinetics, the role of the binder phase in the densification process and how sintering depends on the heating conditions are investigated. It is observed that alloys with different WC particle size show quite different structural evolution during sintering, although the densification mechanisms are the same. This is explained by the formation of agglomerates of WC and Co. Hardmetal alloys can sinter very rapidly when high heating rates are used, since rapid heating accelerates the binder spreading and the formation of WC-Co agglomerates. The binder phase (Co) spreads on the WC particles initially as a thin layer. Subsequently, more Co spreads on this layer and WC-Co agglomerates are formed.

Influence of Grain Growth Inhibitors and Powder Size on the Properties of Ultrafine and Nanostructured Cemented Carbides Sintered in Hydrogen

“…The grain growth of WC-9Co/1 in general is slightly higher compared to WC-6Co/1 consolidated from the same starting powder but with lower Co content. Co content contributed to the recrystallization and grain growth of near nano-and nanostructured cemented carbides sintered in hydrogen, confirming the role of Co in grain growth, already researched by various scientists [11,[13][14][15]. The smallest grain sizes were measured for WC-6Co/2, 95 nm and the addition of Cr 3 C 2 and VC, but in higher content compared to other mixtures.…”

Comparison between microwave and conventional sintering of WC/Co composites

“…The final product consists of a three-dimensional skeleton of WC grains with cobalt as a binder phase matrix. da Silva et al [4] and Cha et al [5] compared the conventional sintering when using fine grained and coarse grained WC, respectively. They found a smaller mean grain size in the sintered product when the fine grained 0921-5093/$ -see front matter © 2004 Elsevier B.V. All rights reserved.…”

Effect of Magnetic Pulsed Compaction (MPC) on Sintering Behavior of Materials

“…Here, the conventional explanation of the sintering mechanism of WC-Co comprises of some of the WC dissolving into the cobalt binder phase, migrating and re-precipitating on the surface of the original WC (Schwartzkopf & Kiefer, 1960). The final product consists of a three-dimensional skeleton of WC grains with cobalt as a binder phase matrix (Silva et al, 2001;Cha et al, 2001). In hard alloys such as WC-Co or TiC, even a slight difference in hardness value with respect to their constituents' content, pressure or grain size can mean a change to their mechanical behavior.…”