After many years’ attendance at one of the world's most important PM conferences, MPIF's Powdermet, I have become used to my favorite subject – sintered carbides – being relegated to smallest rooms, lesser space in the program and even so-called parallel conferences. This contrasts with the attitude of EPMA's annual European conference, where its major 2016 event, also the World Congress, celebrates the 90th anniversary of hardmetal cutting tools, by value the most important PM products, with a plethora of papers and a special seminar on sintered carbide history.
It was thus a pleasant surprise to find that at Powdermet 2016 in Boston's elegant Back Bay Sheraton hotel, the first session was devoted to sintered carbides, and that the two thought-provoking papers, each from a different continent, were decidedly worth reporting to MPR readers.
Here's the first, presented by Johannes Pötschke of Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Dresden, Germany, and titled:
Novel polycrystalline WC/Co-based cemented carbides and their properties
Most sintered (or cemented) carbides consist of monocrystalline tungsten carbide (WC) particles in a pseudoeutectic matrix of WC in metallic cobalt. Their major properties, indentation hardness and ‘toughness’ depend largely on WC particle shape and grain size, though there are other important factors such as grain size distribution, degree of WC recrystallization during liquid-phase sintering, binder distribution especially at grain boundaries, additional alloying elements and binder saturation with WC. The researcher looked mainly at grain size and cobalt content, where, in general, smaller grain size and lower Co content give greater hardness but lesser toughness, and of course the reverse.
This article appeared in the Jan/Feb issue of Metal Powder Report.
