Author: Y.Suh†, M.Kim, H.Kim and J.Kim*Title: Oxidative Breakup of Cemented Carbide Scrap by CuO-flux RoastingJournal: International Journal of Refractory Metals and Hard MaterialsYear: 2024Impact factor: 3.6Abstract:Tungsten carbide‑cobalt (WC-Co) composites are widely used in industry as hardmetals with superior properties and performance; however, these qualities make it difficult to recycle components made of WC-Co at their end-of-life. Herein, we present a one-step CuO-flux roasting process in which a solid-state flux supplies sufficient oxygen for the full oxidation of a hardmetal tool piece when melted. Computational assessments of the Gibbs energy of formation and its tendency to form alloys reveal that CuO is suitable for oxidizing WC cutting tools at high temperatures. After roasting a WC-Co cutting insert covered with CuO powder at 1048 °C, the insert loses its shape and changes into a friable solid oxide mass. As the oxidation reaction is highly exothermic and sustainable, the temperatures of the reactants can exceed the melting points of the oxides produced. Meltable oxide-flux roasting can be applied to the recycling of hardmetals, such as carbides and nitrides.

Author: H.Lee†, H.Kim, J.Kwak, S.Kyung and J.Kim*Title: Mechanical Properties of (Zr1-xMx)B2 and (Hf1-xMx)B2 (M=Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W) for Diboride Fiber Materials: Ab Initio CalculationsJournal: Textile Science and EngineeringYear: 2024Impact factor:Abstract:Zirconium diboride (ZrB2) and hafnium diboride (HfB2) fibers have not been studied as extensively as metal carbides and nitrides for transition metal solid solutions due to a lack of processing technology. However, their remarkable physical properties make them ideal for high-temperature applications. In this study, we investigated the mechanical properties of solid solution diboride using ab initio calculations. Specifically, we focused on the (Zr1-xMx)B2 and (Hf1-xMx)B2 (M=Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W) compositions. Our findings revealed that ZrB2 and HfB2 have high Young’s moduli of 524.12 and 551.41 GPa, respectively. Additionally, the solid solutions of (Zr0.25Ti0.75)B2 and (Hf0.25Ti0.75)B2 showed superior shear and Young's modulus. We also compared the mechanical properties of titanium-doped diboride solid solutions with undoped ZrB2 and HfB2 at high temperatures. Our study provides valuable insights into the potential development of diborides as ceramic fibers tailored for hightemperature applications.

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