TY - JOUR A1 - Huang, S.G. A1 - Vanmeensel, K. A1 - Mohrbacher, H. A1 - Woydt, Mathias A1 - Vleugels, J. T1 - Microstructure and mechanical porperties of NbC-matrix hardmetals with secondary carbide addition and different metal binders JF - International journal of refractory metals & hard materials N2 - NbC has a relatively high hardness (19.6 GPa) and melting temperature (3600 °C) and is usually applied as a grain growth inhibitor in WC–Co hardmetals. The current study reports on the influence of the sintering technology and overall chemical composition on the microstructure and mechanical properties of NbC-based hardmetals, using Co as a binder. The partial replacement of NbC by 5 wt.% WC, Mo2C, VC or TiC allows one to significantly improve the hardness and toughness of the NbC–Co materials. The influence of different binders, i.e., Co, 316L stainless steel and Fe3Al on the microstructure and mechanical properties of NbC-based hardmetals was also investigated. The powder mixtures were sintered in the solid state by PECS and liquid state by conventional vacuum sintering. Detailed microstructural analysis was conducted by EPMA elemental mapping and WDS point analysis. Mechanical properties, including Vickers hardness and indentation toughness were assessed. KW - Niobium carbide KW - Sintering KW - Grain growth KW - Microstructure KW - Mechanical properties PY - 2015 DO - https://doi.org/10.1016/j.ijrmhm.2014.10.014 SN - 0263-4368 SN - 0958-0611 VL - 48 SP - 418 EP - 426 PB - Elsevier AN - OPUS4-31974 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Huang, S. G. A1 - Vleugels, J. A1 - Mohrbacher, H. A1 - Woydt, Mathias T1 - Microstructure and tribological performance of NbC-Ni cermets modified by VC and Mo2C JF - International Journal of Refractory Metals & Hard Materials N2 - The current study reports on the influence of the Addition of 5–15 vol% VC or/and Mo2C carbide on the microstructure and mechanical properties of nickel bonded NbC cermets, which are compared to cobalt bonded NbC cermets. The NbC, Ni and secondary carbides powder mixtures were liquid phase sintered for 1 h at 1420 °C in vacuum. The fully densified cermets are composed of a cubic NbC grains matrix and an evenly distributed fcc Ni binder. NbC grain growth was significantly inhibited and a homogeneous NbC grain size distribution was obtained in the cermets with VC/Mo2C additions. The mechanical properties of the NbC-Ni matrix cermets are strongly dependent on the carbide and Ni binder content and are directly compared to their NbC-Co equivalents. The liquid phase sintered NbC-12 vol% Ni cermet had a modest Vickers hardness (HV30) of 1077 ± 22 kg/mm2 and an indentation toughness of 9.1 ± 0.5 MPa·m1/2. With the addition of 10–15 vol% VC, the hardness increased to 1359 ± 15 kg/mm2, whereas the toughness increased to 11.3 ± 0.1 MPa·m1/2. Addition of 5 and 10 vol% Mo2C into a NbC-12 vol% Ni mixtures generated the same values in HV30 and KIC when compared to VC additions. A maximum flexural strength of 1899 ± 77 MPa was obtained in the cermet with 20 vol% Ni binder and 4 vol% VC+4 vol% Mo2C addition, exhibiting a high fracture toughness of 15.0 ± 0.5 MPa·m1/2, but associated with a loss in hardness due to the high Ni content. The dry sliding wear behaviour was established at room temperature and 400 °C from 0.1 to 10 m/s. KW - Cermet KW - Liquid phase sintering KW - Grain growth KW - Wear KW - Niobium carbide PY - 2017 DO - https://doi.org/10.1016/j.ijrmhm.2017.03.012 SN - 0263-4368 VL - 66 SP - 188 EP - 197 AN - OPUS4-40505 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Huang, S. G. A1 - Vleugels, J. A1 - Mohrbacher, H. A1 - Woydt, Mathias T1 - NbC-based cermets: influence of secondary carbide addition and metal binder T2 - Proceedings of the International Symposium on Wear Resistant Alloy for the Mining and Processing Industry N2 - Full densification of Fe, Co and Ni bonded NbC based cermet’s was achieved by pressure less liquid phase sintering in vacuum for one hour at 1420°C. The hardness and toughness of the NbC matrix cermet’s can be mainly tailored by the binder composition and secondary carbide additions. Ni binder based NbC cermet’s allow the combination of high hardness and improved toughness. The addition of lesser amounts of VC/Cr3C2 in a NbC partially substituted WC-Co cemented carbide increased significantly the hardness in combination with a moderate fracture toughness. T2 - International Symposium on Wear Resistant Alloys for the Mining and Processing Industry CY - Sao Paulo, Brazil DA - 04.05.2015 KW - Niobium carbide KW - Hardmetal KW - Cemented carbide KW - Sintering KW - Grain growth KW - Microstructure KW - Hardness KW - Fracture toughness PY - 2018 SN - 978-0-692-05382-9 SP - 521 EP - 534 AN - OPUS4-44206 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -