TY - JOUR A1 - Woydt, Mathias A1 - Mohrbacher, H. T1 - Friction and wear of binder-less niobium carbide N2 - The tribological profile of alumina (99.7%) mated against binder-less niobium carbide (NbC) rotating disks were determined unidirectional sliding tests (0.1–7.5 m/s; 22 °C and 400 °C) as well as in oscillation tests (f=20 Hz, Δx=0.2 mm, 2/50/98% rel. humidity, n=105/106 cycles) under un-lubricated (dry) conditions. In addition, the microstructure and mechanical properties of NbC were determined as well. The reason for testing hot-pressed NbC was to avoid side effects generated by sintering additives and/or second phases. The tribological data obtained were benchmarked with different ceramics, cermets and thermally sprayed coatings. NbC exhibited low wear rates under dry sliding associated with high load carrying capacity. The tribological profile established revealed a strong position of NbC under tribological considerations and for closed tribo-systems against traditional references, such as WC, Cr3C2, (Ti,Mo)(C,N), etc. KW - Sliding friction KW - Sliding wear KW - Ceramic KW - Coating KW - NbC PY - 2013 U6 - https://doi.org/10.1016/j.wear.2013.07.013 SN - 0043-1648 VL - 306 IS - 1-2 SP - 126 EP - 130 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-28985 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Woydt, Mathias A1 - Mohrbacher, H. T1 - Tribological profile of binderless niobium carbide N2 - The tribological profile of alumina (99,7%) mated against binderless niobium Carbide (NbC) rotating disks under under unlubricated (dry) friction and the type of motions of unidirectional sliding (0.1 m/s to 7.5 m/s; 22°C and 400°C) and oscillation (f= 20 Hz, Ax= 200 mm, 2/50/98% rel. humidity, n= 105/106 cycles) was determined including the microstructure and mechanical properties. The obtained tribological data were benchmarked with different ceramics, cermets and thermally sprayed coatings. The established tribological profile revealed a strong position of NbC under tribological considerations and for closed tribosystems against traditional references, like WC, Ci‘3C2, (Ti,Mo)(C,N), etc.. T2 - 37th International Conference on Advanced Ceramics and Composites CY - Daytona Beach, FL, USA DA - 27.01.2013 PY - 2013 SN - 978-1-118-83995-9 SP - Datei 01/20 reviewed, 5 pages PB - Wiley AN - OPUS4-29461 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Woydt, Mathias A1 - Mohrbacher, H. A1 - Vleugels, J. A1 - Huang, S. T1 - Niobium carbide for wear protection - tailoring its properties by processing and stoichiometry N2 - Niobium carbide is a hardly explored carbide but its functional profile shows a high potential for wear protection and tribological applications, which are currently dominated by tungsten carbide. Surprisingly little information is available on niobium carbide (NbC). Niobium carbide can be either synthesized by carbothermal conversion of Nb2O5 or be metallurgically grown and leached out. Furthermore, NbC hardmetal grades can be bonded by all known metallic binders and processed and sintered in exactly the same way as WC-based hardmetals. Niobium is today largely available. NbC can be efficiently produced, provides comparably low friction in many relevant tribo-contacts and displays low wear. NbC and Nb2O5 have so far no REACH classification related to human toxicology and are not listed as substances of very high concern contrary to WO3 and Co3O4. This contribution demonstrates the key characteristics of NbC and discusses its sustainability and reliable value chain. KW - niobium carbide KW - wear KW - machining PY - 2016 U6 - https://doi.org/10.1016/j.mprp.2015.12.010 SN - 0026-0657 VL - 71 IS - 4 SP - 265 EP - 272 PB - Elsevier Ltd. AN - OPUS4-37150 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - 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 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 U6 - 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 - CONF A1 - Woydt, Mathias A1 - Mohrbacher, H. T1 - Niobcarbid - Ein vergessener Hartstoff für den Verschleißschutz in offenen und geschlossenen Tribosystemen N2 - Das triboiogische Profil von binderlosem NbC und mit 8% bzw. mit 12% Cobalt oder 12% FeaAl gebundenem NbC wird unter unidirektionaler Gleitreibung (v= 0,1-10 m/s, T= 22°C und 400°C) und unter oszillierender Gleitreibung vergleichend gegenüber Ingenieurkeramiken und Hartmetallen dargestellt. Zusätzlich werden die 4-Punkt-Biegebruchfestigkeit, elastische Eigenschaften (E,G) bis 1.000°C die lastabhängige Mikrohärte sowie die Phasenzusammensetzung und Gefügestrukturen vorgestellt. Die Verschleißkoeffizienten des binderlosen NbC lagen bei T unterhalb von 10'6mm31 / *N* m, während diejenigen der cobaltgebundenen NbCs mit ansteigender Gleitgeschwindigkeit von 2-4 10‘6 mm3/Nm bei 0,1 m/s auf 5-7 10"7 mm3/Nm bei 10 m/s abnahmen. Die Verschleißkoeffizienten bei 400°C lagen für die NbCs generell unterhalb von 10‘6 mm3/Nm. Das triboiogische Lasttragevermögen im Trockenlauf, ausgedrückt als PV-Wert, nimmt mit ansteigender Gleitgeschwindigkeit auf 100 W/mm2 zu. Bedingt durch die geringe Löslichkeit von NbC in Legierungen offenbarten erste Zerspanversuche mit verschiedenen Stählen eine gegenüber WC-basierten Schneidstoffen signifikant angehobene Zerspanungsvolumina. Somit offenbart NbC in offenen und geschlossenen Tribosystemen Anwendungspotentiale. T2 - 55. Tribologie-Fachtagung - Reibung, Schmierung und Verschleiß - Forschung und praktische Anwendungen CY - Göttingen, Germany DA - 22.09.2014 PY - 2014 SN - 978-3-00-046545-1 VL - II SP - 03/1 EP - 03/14 AN - OPUS4-31531 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Woydt, Mathias A1 - Mohrbacher, H. T1 - The use of niobium carbide (Nbc) for wear resistant tribosystems and the tribological backgrounds as cutting tools N2 - The tribological profile of rotating disks made in binder-less niobium Carbide (hot-pressed NbC) and cobalt-bonded NbCs (NbC-8Co and NbC-12Co) mated against alumina (99.7%) were determined under unidirectional sliding tests (0.1 m/s to 8.0 m/s; 22°C and 400°C) as well as in oscillation tests (f= 20 Hz, Ax= 0.2 mm, 2/50/98% rel. humidity, n= 105/l 06 cycles) under unlubricated (dry) conditions. In addition, the microstructure and mechanical properties of HPNbCl and NbC bonded with 8 vol.-% and 12 vol.-% cobalt were determined as well. The tribological data obtained were benchmarked with different ceramics, cermets, hard metals and thermally sprayed coatings, where the NbCs bonded with 8% and 12% Co presented above 7 m/s the lowest wear rates so far in such a bench mark. HP-NbCl, NbC-8Co and NbC-12Co exhibited low wear rates under dry sliding associated with PV high load carrying capacities. The tribological profile established revealed a strong position of NbC bearing materials under tribological considerations and for closed tribo-systems against traditional references. T2 - 9th International conference on tungsten, refractory & hardmaterials CY - Orlando, FL, USA DA - 18.05.2014 KW - Friction KW - Wear KW - Ceramic KW - Oscillation KW - NbC KW - Niobium carbide KW - Cobalt KW - Hard metal KW - Strength KW - Sliding KW - Modulus KW - High temperatures PY - 2014 SN - 978-0-9853397-7-7 SP - 222 EP - 232 AN - OPUS4-31630 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Woydt, Mathias A1 - Mohrbacher, H. T1 - The tribological and mechanical properties of niobium carbides (NbC) bonded with cobalt of Fe3Al N2 - The tribological and mechanical properties of niobium carbide bonded with 8 vol.-% (NbC-8Co), 12 vol.-% of cobalt (NbC-12Co) or 12 vol.-% of Fe3Al (NbC-12Fe3Al) are presented. Rotating discs made of metal-bonded niobium carbide were mated against alumina (99.7%) under unlubricated (dry) unidirectional sliding tests (0.1 m/s to 12.0 m/s; 22 °C and 400 C) as well as in oscillation tests (f=20 Hz, Δx=0.2 mm, 2/50/98% rel. humidity, n=105/106 cycles). Microstructure and phase compositions were determined as well. The tribological data obtained were benchmarked with different ceramics, cermets, hard metals and thermally sprayed coatings, where NbC bonded with 8% and 12% Co presented above 7 m/s the lowest wear rates so far in such a benchmark. Binderless NbC (HP-NbC1) and the metal-bonded NbCs exhibited low wear rates under dry sliding associated with P·V high load carrying capacities. NbC-based hard metal bonded with 12 vol.-% of Fe3Al resulted in a higher hardness level than for 12 vol.-% cobalt. The tribological profile established revealed a strong position of NbC-bearing materials under tribological considerations and for closed tribosystems against established reference tribo-couples. KW - Sliding KW - Ceramic KW - Oscillation KW - Strength KW - Modulus KW - High temperatures KW - Friction KW - Wear KW - NbC KW - Niobium carbide KW - Cobalt KW - Fe3Al KW - Hard metal PY - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-316129 SN - 0043-1648 VL - 321 SP - 1 EP - 7 PB - Elsevier CY - Amsterdam AN - OPUS4-31612 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 - Influence of VC and Mo2C on the microstructure and mechanical properties of Ni bonded NbC-cermets N2 - The current study reports on the effect of VC and Mo2C carbides on the microstructure and mechanical properties of Ni bonded NbC cermets. T2 - World PM2016 CY - Hamburg, Germany DA - 09.10.2016 KW - Niobium carbide KW - NbC KW - Liquid phase sintering (LPS) KW - Hard materials PY - 2016 SN - ISBN 978-1-899072-47-7 SP - 1 EP - 7 AN - OPUS4-37891 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Woydt, Mathias A1 - Mohrbacher, H. A1 - Vleugels, J. A1 - Huang, S. T1 - Substitution of tungsten carbide by niobium carbide as cutting materials and for wear protection N2 - Im binären System NbC-C existieren verschiedene Phasen im Homogenitätsbereich NbCₓ, mit 0,75 ≤ x ≤ 1,0, wie NbC, Nb₆C₅ und Nb₄ C₃ , die ein breites Prozessfenster beim Sintern und in der Werkstoffentwicklung ermöglichen. Die Mikrohärte, die Warmhärte, der Verschleißwiderstand, das Elastizitätsmodul und die Zähigkeit von Hartmetallen hängen vom C/Nb-Verhältnis ab, wie auch von der Zugabe von Sekundärcarbiden. N2 - Several phases, like Nb₄ C₃ , Nb₆C₅ and other short and long range ordered phases occur in the region of homogeneity of NbCₓ (0.75 ≤ x ≤ 1.0) in the binary phase diagram. Properties, like micro-hardness, hot hardness, sliding wear resistance, elastic modulus and toughness can be tailored by the C/Nb ratio, the addition of secondary carbides and the type of binder. Supporting results from different grades with varying C/Nb ratio or binder types were illuminated. Thus, the NbC system offers to producers a wider process window, than WC. The impact of these tailored properties on sliding wear and cutting performance was illuminated by tribological and machining results. Niobium is today largely available. NbC can be synthesized by carbothermal conversion of Nb₂O₅ or be metallurgically grown and leached out, provides comparably low friction in many relevant tribo-contacts and displays low wear. NbC and Nb₂O₅ have so far no REACH classification related to human toxicology and are not listed as substances of very high concern contrary to WO₃ and Co₃ O₄ . T2 - 57. Tribologie-Fachtagung CY - Göttingen, Germany DA - 26.09.2016 KW - cutting materials KW - niobium carbide KW - wear protection PY - 2016 SN - 978-3-9817451-1-5 SP - 65/1 EP - 65/14 AN - OPUS4-37833 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Woydt, Mathias A1 - Mohrbacher, H. T1 - Influence of stoichiometry and processing on the tribological profile of hardmetals based on niobium carbide (NbC) N2 - The tribological behavior under dry sliding of a Fe3Al-NbC composite prepared by pyro-metallurgical synthesis is compared to different SPS sintered NbC-based hardmetals bonded by cobalt or Fe3AI. The dry sliding wear resistance (0. 1-7 /10 m/s) of the present Fe3Al-NbC with -60 % NbC was close to those known ofNbC-based hard metals. No grain pull-outs or fragmentations of the NbC grains were seen in the wear tracks of the Fe3Al-NbC composite, as a metallurgical interphase was formed between matrix and NbC grains. The physical prope1ties of melt grown NbC match those known from powder metallurgically sintered NbC using powders converted from Nb205. T2 - International conference on powder metallurgy & particulate materials 2015 CY - San Diego, USA DA - 17.05.2015 PY - 2015 SN - 978-1-943694-01-3 SP - 08-83 EP - 08-91 CY - Princeton, NJ, USA AN - OPUS4-34884 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -