TY - CONF A1 - Woydt, Mathias A1 - Mohrbacher, H. T1 - Adjusting the functional properties of niobium carbide N2 - The process window and range of functional properties of NbC is wide, because micro-hardness, hot hardness, sliding wear resistance, elastic modulus and toughness can be tailored by the C/Nb ratio, because Nb4C3, 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, and by the type of binder. Further improvements enable the addition of secondary carbides. Supporting results from literature and 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. NbC can be synthesized by carbothermal conversion of Nb2O5 or be metallurgically grown in melts and leached out as coarse NbC cubes. NbC provides comparably lower 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. T2 - 2016 International Conference on Powder Metallurgy & Particulate Materials CY - Boston, MA, USA DA - 05.06.2016 KW - Niobium carbide KW - NbC KW - Wear KW - Friction PY - 2016 AN - OPUS4-36497 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 JF - Metal Powder Report 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 DO - 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 - CONF A1 - Woydt, Mathias T1 - Tribological profile of hydraulic oils by using SRV N2 - Hydraulic oils are well established formulations developed around the pump test. Requirements for energy efficiency and also environmentally acceptable properties increased the demand for development. In the same time, system pressure and the used of servo-hydraulic vanes increased bringing specific formulations and materials to their limit. The vane pump is a key component in hydraulic systems and many other tribosystems in hydraulic circuits operate under different tribological operating conditions. The concept for ranking of hydraulic oils consists in using existing SRV-based ASTM test methods for evaluation of friction, wear and extreme pressure properties: D6425, friction and wear of oils (homologue to DIN 51834-2), D7421, extreme pressure properties of oils and D7755, wear volumes of ball and disks (homologue to DIN 51834-3. The tribological properties are assessed under the regime of mixed/boundary lubrication The SRV-based concept of tribological profile generates the wear volumes on two triboelements (specimen) and the extreme pressure properties as well as the evolution of friction in the wear and extreme pressure load step test. Thus, the benchmark and validation of hydraulic oils bear on a wider range of tribological properties. Round robin test results using the aforementioned testing concept will be shown. Another outcome is tribological set limits for inclusion in hydrau¬lic oil speci¬fications. T2 - Workshop on Tribological Testing of Components Using the SRV Test Machine CY - Bellevue, WA, USA DA - 30.06.2016 KW - Tribology KW - Hydraulic oils KW - SRV KW - ASTM test method KW - Friction KW - Wear PY - 2016 AN - OPUS4-36734 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Woydt, Mathias T1 - The identification in engine or gear tests of the induction time or off-set point („cliff“), after which wear and friction increased N2 - In the state-of-the-art technology, the impact of additives on friction and wear is evaluated in recipes with fixed concentrations. For the development of formulations it is desirable to determine the lowest effective concentration or the concentration at which failure was initiated or excessive wear began. Through a new development of the SRV® machine it is now possible to change the lubricant composition of a test specimen in a reproducible manner, in sub-pro Mill steps during the SRV® testing. This technology is used in the present article to define the optimum additive concentration with regard to wear and friction in a system of base oil and additive. Exemplary selected base oil and additive variants are tested here. The load parameters during testing are selected in such a way that they correspond to later application. The new data acquisition capabilities enable new possibilities for optimizing lubricant formulations in practice-oriented model-tribometer tests. “Cliff“ testing aims to identify in engine or gear tests the induction time or off-set point (“cliff“) after which wear and friction increased of failure occurred. Explanations for friction and wear increased as well as failures, which occurred during engine tests, can be derived from SRV® testing of oil samples taken or collected at different engine test times and correlating these with their friction, wear and EP data in respect to depleting curves for specific additives or other oil properties. A “cause-root” analysis is done by plotting SRV® data versus functional properties. The collected oil samples must be fully SRV® tested and chemically analyzed. T2 - Workshop on Tribological Testing of Components Using the SRV Test Machine CY - Bellevue, WA, USA DA - 30.06.2016 KW - Cliff testing KW - Additives KW - SRV machine KW - Friction KW - Wear behavior PY - 2016 AN - OPUS4-36743 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Woydt, Mathias T1 - Substituting tungsten carbide (WC) as cutting tools and for wear protection by niobium carbide (NbC) N2 - As a refractory carbide, niobium carbide (NbC) is today still a forgotten carbide with hidden properties, such as wear resistance, thus qualifying NbC for the group of tribological materials with enhanced wear resistance. Several phases, like Nb₄C₃, 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, which enable the tailoring of properties and offers a much wider process window than known from WC. The type binder (Co, Ni, NiMo) and its concentration as well as the sintering process (SPS, liquid phase sintering) determine the box “hardness-toughness”, which will be illuminated based on more than 100 grades. The impact of these tailored properties on sliding wear (T= 22/400°C; v= 0,1-10 m/s) and cutting performance will be illuminated by tribological and machining results. Cutting test results under emulsion and coolant-free operation of cobalt and Fe3Al bonded, straight NbC versus WC based inserts against different alloys (C60, 100Cr6, 42CrMo4, X90CrMoV18, 300WA, GG35) will be highlighted. T2 - STLE 2016 Annual Meeting and Exhibition CY - Las Vegas, NV, USA DA - 15.05.2016 KW - Niobium Carbide (NbC) KW - Friction KW - Wear PY - 2016 AN - OPUS4-36152 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Genga, R. M. A1 - Cornish, L. A. A1 - Woydt, Mathias A1 - van Vuuren, J. A1 - Polese, C. T1 - NbC: A machining alternative for dry and MQL face-milling of grey cast rion (GCI) T2 - World PM 2016 N2 - NbC was studied as the major carbide phase with Ni and Co binders, produced by both spark plasma sintering (SPS) and liquid phase sintering (LPS), and tested as cutting inserts during dry and MQL (Minimum quantity lubrication) face-milling of grey cast iron (GCI) (BS 1452, Grade 17). T2 - World PM2016 CY - Hamburg, Germany DA - 09.10.2016 KW - Niobium carbide KW - NbC KW - Machining KW - Spark plasma sintering (SPS) KW - Liquid phase sintering (LPS) PY - 2016 SN - ISBN 978-1-899072-47-7 SP - 1 EP - 6 AN - OPUS4-37889 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 T2 - World PM 2016 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 - JOUR A1 - Kanematsu, W. A1 - Mandler, W. A1 - Manier, Charles-Alix A1 - Woydt, Mathias T1 - Rolling contact fatigue tests of ceramics by various methods: comparison of suitability to the evaluation of silicon nitrides JF - Journal of Testing and Evaluation N2 - Results of rolling contact fatigue (RCF) tests by balls-on-rod (BOR) method and two-roller methods have been compared to those by the balls-on-flat (BOF) method by using three different silicon nitride grades. The results suggest that the two-roller method could differentiate the bearing grade materials in terms of wear behavior. KW - Rolling contact fatigue KW - Slip-rolling resistance KW - Spall KW - Wear KW - Balls-on-flat KW - Balls-on-rod KW - 2Disk KW - Silicon nitride PY - 2016 DO - https://doi.org/10.1520/JTE20140258 SN - 0090-3973 SN - 1945-7553 VL - 44 IS - 3 SP - 1271 EP - 1283 PB - ASTM International CY - West Conshohocken/PA, USA AN - OPUS4-37928 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Genga, R. A1 - Cornish, L. A1 - Woydt, Mathias A1 - van Vuuren, A. J. A1 - Polese, C. T1 - Face-milling of grey cast iron (BS 1452) using WC-based and NbC-based cutting tools T2 - International Tooling Conference N2 - NbC was studied as the major carbide phase with Ni and Co binders, produced by both spark plasma sintering (SPS) and liquid phase sintering (LPS), and tested as cutting inserts during dry and MQL (Minimum quantity lubrication) face-milling of gey cast iron (GCI) (BS 1452, Grade 17). T2 - 10th Tool Conference 2016 - TOOL 2016 CY - Bratislava, Slovakia DA - 04.10.2016 KW - NbC KW - Spark plasma sintering KW - Ni KW - Mechanical properties KW - Flank wear KW - Chemical stability PY - 2016 SN - ISBN 978-3-200-04786-0 SP - 336 EP - 342 AN - OPUS4-37869 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Uhlmann, E. A1 - Kropidlowski, K. A1 - Sammler, F. A1 - Richarz, S. A1 - Woydt, Mathias T1 - Niobium carbide as an alternative cutting tool material T2 - International Tooling Conference N2 - Niobium carbide (NbC) is an alternative cutting material. The Federal Institute for Materials Research and Testing (BAM) and the Institute for Machine Tools and Factory Management (IWF) of the TU Berlin assessed the cutting suitability of NbC with cobalt (Co)-binder compared to WC with Co-binder in the machining of a wide range of materials. T2 - 10th Tool Conference 2016 - TOOL 2016 CY - Bratislava, Slovakia DA - 04.10.2016 KW - Niobium carbide (NbC) KW - Tungsten carbide (WC) KW - Cutting material KW - Tool wear KW - Turning trials KW - Wear mechanisms PY - 2016 SN - ISBN 978-3-200-04786-0 SP - 365 EP - 373 AN - OPUS4-37870 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 T2 - Reibung, Schmierung und Verschleiß 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 - JOUR A1 - Kloß, Heinz A1 - Woydt, Mathias T1 - Prediction of tribological limits in sliding contacts: flash temperature calculations in sliding contacts and material behavior JF - Journal of Tribology N2 - In order to achieve greater efficiency or to meet light weight requirements, components are downsized. This, however, increases the load, e.g., Hertzian or nominal contact pressures and stresses of tribosystems. This load is expressed as pₐ·v-value, the product of nominal contact pressure and sliding velocity. pₐ·v-values are an effective tool for design engineers for predicting low wear/high wear transitions. Therefore, in the present work, topographical analysis has been combined with the plasticity of micro-asperities and the flash temperatures to estimate the limits of pₐ·v diagrams. The central piece of this set of models presented here is the calculations for flash temperatures and contact mechanics of micro-asperities. This central piece is used to predict the performance of materials in high velocity (turbines, machinery) and low velocity (human joint) applications. It is shown that the model combination suggested here is a useful tool for screening and preselecting a candidate and new materials with respect to tribological requirements before engaging in expensive testing. KW - Hot spot KW - Flash temperature KW - Micro-asperity KW - Abrasive wear KW - Turbine KW - Artificial hip joint KW - Low wear/high wear transition PY - 2016 DO - https://doi.org/10.1115/1.4033132 SN - 0742-4787 SN - 1528-8897 VL - 138 IS - 3 SP - 031403-1 EP - 031403-11 PB - The American Society of Mechanical Engineers AN - OPUS4-36122 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wäsche, Rolf A1 - Woydt, Mathias T1 - Tribological characterization of niobium carbide with different binder materials T2 - Tribology for sustainable development N2 - Wear of Niobium carbide with nickel binder has been experimentally characterized under dry, oscillating sliding conditions against steel and a-alumina up to 600°C. T2 - National Tribology Conference/NTC-2016 CY - Varanasi, India DA - 08.12.2016 KW - Niobium carbide KW - Wear resistance KW - Binder PY - 2016 SP - 1 EP - 2 AN - OPUS4-38879 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 mechanical properties of NbC matrix cermets using Ni containing metal binder JF - Metal Powder Report N2 - The current study reports on the effect of the addition of Al metal and secondary refractory carbides on the microstructure and mechanical properties of Ni bonded NbC matrix cermets. KW - NbC KW - Niobium carbide KW - Hardness KW - Hard materials PY - 2016 DO - https://doi.org/10.1016/j.mprp.2016.05.009 VL - 71 IS - 5 SP - 349 EP - 355 PB - Elsevier Ltd. AN - OPUS4-44623 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Burbank, John A1 - Woydt, Mathias T1 - Optimization of pre-conditioned cold work hardening of steel alloys for friction and wear reductions under slip-rolling contact JF - Wear N2 - The goal of reducing CO2 emissions in the automobile industry has led to the development of increasingly efficient lightweight material solutions that yield enhanced performance. In light of this goal, this current work involves the optimization of the pre-conditioning of novel, high toughness steel bearings without thermo-chemical treatment, with the aim of transferring the running-in phase into the final step of the mechanical finishing process. A case-hardened gear steel and two novel non-case-hardened steels were evaluated. KW - Work hardening KW - Steel KW - Gear KW - Bearing KW - Residual stress KW - Hardness PY - 2016 DO - https://doi.org/10.1016/j.wear.2016.01.011 SN - 0043-1648 VL - 350-351 SP - 141 EP - 154 PB - Elsevier B.V. CY - Amsterdam, u.a. AN - OPUS4-35665 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Woydt, Mathias A1 - Mohrbacher, H. T1 - Tailoring the functional properties of niobium carbide N2 - Several phases, like Nb₄C₃, 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 Co₃O₄. T2 - 40th International Conference and Exposition on Advanced Ceramics and Composites CY - Daytona Beach, FL, USA DA - 24.01.2016 KW - Niobium carbide KW - Hard metal KW - Wear KW - Friction KW - Machining KW - Cutting KW - Metal matrix composite PY - 2016 SP - Paper: 2347292, 1 EP - 13 AN - OPUS4-35640 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Woydt, Mathias T1 - 2015 SRV global circular comparison results bulletin N2 - Tribological profile of hydraulic oils by using SRV. The determination of a set of critical, tribological by using different SRV-based test methods. The SRV-based concept of tribological profile generates the wear volumes on two triboelements (specimen), the extreme pressure properties and friction under different contact pressures. Thus, the benchmark and validation of hydraulic oils bear on a wider range of tribological properties. The RR2016 extends with six hydraulic oils to other base oil types including biodegradable fluids, which were all tested according to ASTM D7043 in order to consolidate the correlation between SRV and V104C. T2 - Working Group Meeting about SRV in China 2016 CY - Beijing, China DA - 05.04.2016 KW - SRV KW - Standards KW - China PY - 2016 AN - OPUS4-35744 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Woydt, Mathias T1 - 2016 SRV global circular comparison results bulletin N2 - Actions from the meeting in April 2016: 1. Four SAC test methods are in place and were revised: SH/T 0721 (Grease, coefficient of friction and wear), SH/T 0784 (Grease, pass load/O.K. load), SH/T 0847 (Oil, coefficient of friction and wear) and SH/T 0882 released by 11-2014 (Oil, pass load/O.K. load). 2. New test method to evaluate anti-fretting properties of greases based was approved by SAC TC280 and will be released. 3. SAC TC280 accepted the project “Simulation of synchronizer by using SRV”. Draft text to be submitted by 03-2017. Discussions on a parallel ASTM test method. 4. A procedure for “Wear Volume” is under development for SAC TC280. T2 - Working Group Meeting about SRV in China 2016 CY - Beijing, China DA - 05.04.2016 KW - SRV KW - Standards KW - China PY - 2016 AN - OPUS4-35745 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Woydt, Mathias T1 - Recent work of the global SRV working group and the development trend of SRV standards N2 - „Cliff“-testing by using SRV The identification in engine or gear tests of the induction time or off-set point („cliff“), after which wear and friction increased. “Cliff” testing as auxiliary method supports the interpretation of engine tests, as it enhances the values of expensive engine tests, because it enables correlations between friction & wear, either from engine or in SRV tests, with additive depletion, oxidation, viscometrics and dispersancy/detergency. Oil samples taken in discrete intervals and “Cliff” tested monitors the evolution of tribological and functional properties versus engine running time. “Cliff” testing by using SRV is a purposeful tool in order to secure and accelerate metallurgical developments and the development of lubricant formulations. T2 - Working Group Meeting about SRV in China 2016 CY - Beijing, China DA - 05.04.2016 KW - SRV KW - Standards KW - China PY - 2016 AN - OPUS4-35747 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 - Densification and tribological profile of niobium oxide JF - Wear N2 - The origin of the intrinsic wear resistance of NbC-based materials is investigated through an assessment of the tribological performance of fully dense, crack-free spark plasma sintered Nb2O5 (here as a reduced polymorph: monoclinic Nb12O29 or NbO2.416). The most likely wear mechanism on NbC is the tribo-oxidation to Nb2O5. The unlubricated (dry) friction and wear behavior of alumina (99.7%) mated against rotating disks of crack-free niobium(V)oxide (Nb2O5) under unidirectional sliding (0.03–10m/s; 22°C and 400°C) and oscillation (f=20 Hz, dx=200 mm, 2/50/98% rel. humidity, n=105/106 cycles) will be presented. The microstructure and mechanical properties of the crack-free Nb2O5 are assessed. The tribological data obtained are benchmarked with different NbC grades, ceramics, cermets and thermally sprayed coatings. KW - Friction KW - Wear KW - Nb2O5 KW - Nb12O29 KW - Niobium oxide KW - Strength KW - Modulus KW - High temperatures PY - 2016 DO - https://doi.org/10.1016/j.wear.2016.02.003 SN - 0043-1648 VL - 352-353 SP - 65 EP - 71 PB - Elsevier B.V. AN - OPUS4-35805 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Burbank, John A1 - Woydt, Mathias T1 - Friction and wear reductions in slip-rolling steel contacts through pre-conditioned chemical tribofilms from bismuth compounds JF - Wear N2 - Downsizing in mechanical systems requires effective lubrication strategies to ensure that increased contact stresses do not cause critical material failure during operation. Additionally, eco-toxicological consideration are becoming increasingly important. In this regard, the goal of this investigation is to transfer the running-in phase into the final step of the mechanical finishing process through the targeted pre-conditioning of novel, high toughness steel bearings without thermo-chemical treatments and compare these to conventional, case-hardened Steels. Pre-conditioning involved implementation of the ecologically sustainable, bismuth-based additives to generate chemically reactive tribofilms on slip-rolling contacts by using a formulation with a high concentration of tribofilm forming additive. Generated tribofilms were analyzed by Raman spectroscopy to elucidate their molecular composition and, ultimately, determine the reaction mechanisms of bismuth-based tribofilm formation. Tribofilm-protected samples were subjected to slip-rolling endurance testing in a factory fill engine oil without pre-conditioning additives to determine the influence of pre-condition tribofilms on friction behavior and wear performance. It was observed that pre-conditioned tribofilms from the bismuth-based additives were able to yield lower coefficients of friction (COF) and profilometric wear coefficients than for Steels without pre-conditioning. Moreover, COF values under mixed/boundary conditions approaching and even less than 0.04 were achieved, thereby rivaling DLC-coated alloy equivalents. KW - tribofilm KW - bismuth KW - carbamate KW - slip-rolling KW - friction KW - wear PY - 2016 DO - https://doi.org/doi:10.1016/j.wear.2016.04.004 SN - 0043-1648 VL - 360-361 SP - 29 EP - 37 PB - Elsevier B.V. AN - OPUS4-35919 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Genga, R. M. A1 - Cornish, L. A. A1 - Polese, C. A1 - Woydt, Mathias A1 - Janse van Vuuren, A. T1 - Wear investigation of NbC inserts during face-milling of grey cast iron T2 - Proceedings of the Microscopy Society of Southern Africa N2 - Tungsten carbide (WC) based cemented carbides have a good combination of hardness, strength and toughness, making them key materials for cutting tool industry. T2 - The 54th Annual Conference CY - Port Elizabeth, South Africa DA - 05.12.2016 KW - Tungsten carbide (WC) KW - Niobium carbide (NbC) KW - Wear KW - Machining PY - 2016 SN - 978-0-620-73767-8 SN - 0250-0418 SP - 1 AN - OPUS4-39388 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -