Program

Technical Program

Status: 3 June, 2022


Wednesday, 1 June, 2022
08:30 - 10:10		Hard Materials - Chemical Vapor Deposition Location: Walter Schwarzkopf Hall Show all Abstracts Hide all Abstracts
08:30	HM 16	Influence of doping agents on the microstructure of CVD-AlTiN Traxler M.¹, Pitonak R.¹, Lessiak M.¹, Weissenbacher R.¹, Todt J.², Jakub Z.², Keckes J.² ¹boehlerit GmbH & Co KG, Austria ²Montanuniversität Leoben, Austria Abstract Hard AlTiN coatings have become industrial standard for applications in high-speed metal machining. The advantage of these coatings lies in their oxidation resistance and high temperature hardness combined with low depositions temperatures compared to state of the art Al2O3-coatings. AlTiN systems are created by both physical and chemical vapour deposition (PVD or CVD) technique. In this contribution, structural, microstructural and functional properties of self-assembled nano-lamellar AlxTix-1xN coatings prepared by CVD process using the gaseous phase with carbon and chloride dopants will be discussed. The coatings were characterized using synchrotron X-ray nanodiffraction, electron microscopy techniques and mechanical tests, which revealed unique process-structure-properties linkages.
08:50	HM 17	Influence of deposition parameters on microstructure and mechanical properties of chemical vapor deposited Ti1-xAlxN coatings Saringer C.¹, Tkadletz M.¹, Thurner J.², Czettl C.², Schalk N.¹ ¹Montanuniversität Leoben, Austria ²Ceratizit Austria GmbH, Austria Abstract Using thermally activated chemical vapor deposition (CVD), it is possible to synthesize Ti1-xAlxN coatings with Al contents up to x > 0.8 in a face-centered cubic crystal structure. This is considered to be due to their self-organized nanolamellar microstructure consisting of lamellae with high Al contents of x > 0.9 epitaxially stacked with lamellae where x ~0.5. However, CVD is a complex process and the formation mechanism of the lamellae and the resulting coating properties are not yet fully understood. Here, we have investigated the impact of the deposition temperature, deposition pressure and rotation speed of the reactive gas feed on the microstructure and mechanical properties. Our results show that by varying the pressure between 10 and 185 mbar and the temperature between 700 and 820 °C the grain size and texture can be tailored. In addition to the amount of wurtzitic AlN formed, they govern the mechanical properties. Similarly, the nanolamella periodicity strongly depends on temperature and pressure, indicating that the reaction kinetics are responsible for their formation rather than the gas feed rotation.
09:10	HM 18	Phase Stability and Stress Evolution in CVD TiAlN Coatings Stiens D.¹, Manns T.¹, Gardecka A.¹, Janssen W.¹, Kümmel J.¹, Bäcke O.², Hörnqvist Colliander M.², Halvarsson M.² ¹Walter AG, Germany ²Chalmers University of Technology, Sweden Abstract This work studies the influence of temperature-induced phase degradation on mechanical properties and structure of cubic CVD TiAlN coatings. Coatings that were pure fcc phase and highly {111} textured in the as-deposited state, according to XRD, were furnace annealed in argon at defined temperatures between 800°C and 1000°C. Changes in the microstructure and the formation of Wurtzite phase h-AlN were observed and characterized by XRD and high resolution electron microscopy. XRD residual stress measurements show that precipitation of h-AlN induces a shift in residual stresses in the coating materials towards compressive stress, which is also reflected in increased microhardness. Machining tests demonstrate a favorable effect on tool lifetime if h-AlN is precipitated in controlled amounts.
09:30	HM 19	Advanced AlTiN coatings for cutting tools Kohlscheen J.¹, Banerjee D.², Lippert M.², Bareiss C.¹, Macshane B.² ¹Kennametal GmbH, Germany ²Kennametal Inc, USA Abstract Titanium-based nitride coatings are widely in machining operations like milling and turning. Adding aluminum to TiN or TiCN helps to increase oxidation resistance and hot hardness of wear resistant coatings. Keeping the desired cubic phase becomes challenging in CVD in general and in PVD at Al:Ti ratios > 2. Following a review of recent achievements by both deposition techniques we will discuss results obtained with the pulsed sputtering technique (PVD HIPIMS). Coating analysis was mainly done by instrumented hardness testing and x-ray diffraction. It will be demonstrated that the metastable cubic AlTiN phase can be stabilized by keeping energy input to the growing film low, i.e. using low pressure and lowered temperature. In addition, manipulating the sequence and energy of incoming ions are suitable to increase the limit of Al concentration before the stable but undesired hexagonal AlN phase forms in considerable amounts. Face milling of cast iron material was used to demonstrate some aspects of the superior behavior of AlTiN PVD coatings with Al contents above 70 at.%.
09:50	HM 20	Effect of Al Content and Crystallographic Orientation of CVD-AlTiN Coating on Failure Mechanism in Face-milling of Alloy Steel Yanagisawa K.¹, Homma H.¹, Okude M.¹ ¹Mitsubishi Materials Corporation, Japan Abstract In this work, 111 and 100 textured cubic AlTiN coatings with high aluminum content were prepared on cemented carbide inserts by thermal CVD method and their failure mechanism in face-milling of alloy steel was investigated. It was found that the chipping caused by thermal cracking led to the end of tool life. The thermal crack density was lower in the 100 textured coating. The thermal crack propagation was suppressed in the coating with high aluminum content, due to its high fracture toughness. In addition, amorphous Al-based oxides were observed on the rake face in the early stages of cutting, which was due to their stability under low oxygen partial pressure. However, as the cutting progressed, the oxides changed to (Fe,Mn,Si,Cr,Mo)Ox which is composed of elements with high content in the workpiece. It was also found that the thicker AlOx was observed on the 100 textured coating than on the 111 textured coating, suggesting that the thicker AlOx and the higher surface coverage contributed to the reduction of the thermal crack density.

10:10 - 10:30		Break Location: Walter Schwarzkopf Hall

10:30 - 12:10		Hard Materials - Powders and P/M processes Location: Walter Schwarzkopf Hall Show all Abstracts Hide all Abstracts
10:30	HM 21	Potentials for WC-Co structures by indirect additive manufacturing Kitzmantel M.¹, Neubauer E.¹, Wallis C.¹ ¹RHP-Technology GmbH, Austria Abstract Additive manufacturing is clearly the emerging technology for small series and special geometries also in the world of hard metals. In the past 2 years we have worked systematically to compare the possibilities for indirect 3D printing using feedstock extrusion (filament: FDM, granules: AIM3D) and highly filled stereolithography. The fabricated samples were analysed and their physical properties recorded to compare the different printing technologies for hard metals by the properties of the finally sintered test coupons. Also show-case prototypes were manufactured and investigated. The study shows, that if homogeneously processed, the materials exhibit properties that can really compete with standard processed ones. Therefor the potential of this technology is shown to grow enormously. Additional features, which additive manufacturing brings on the table, allow products to increase their already high performance. E.g. inner cooling channels in turning tools enhance the lifetime of the tools themselves and increase the performance during cutting. All the work is performed during the research project Wear-O and verified by national (TU Vienna) and international (KIT, PtU) academic partners.
10:50	HM 22	Liquid flow and shape distortion of WC-Co cemented carbides during sintering Saito T.¹, Matsubara H.², Fukuichi Y.¹, Kajiwara T.¹ ¹Kyoritsu Gokin Co., Ltd., Japan ²Tohoku University, Japan Abstract WC-Co cemented carbides sometimes make unexpected shape distortions during sintering, which are not explained by either the non-uniformity of the green density or the gravity effect. Mechanisms of such shape distortions are investigated in detail. Firstly, the relation between the shape distortion and the liquid flow is studied using joined planes of sintered WC-Co cemented carbides at 1673 K, similar to the diffusion couple, with different Co content, WC grain size and carbon content. Secondly, the relation between the liquid flow and the shape distortion in WC-Co round bars are studied in each stage of sintering such as heating under temperature gradient, keeping at 1673 K under uniform temperature, and cooling under temperature gradient. Thirdly, the relation between the liquid flow and the shape distortion in WC-Co bi-layer round bars with different carbon content sintered at 1673 K are studied. We found that the liquid flow during sintering induced the shape distortion and the liquid flow during cooling is critical for the shape distortion. Driving forces of the liquid flow are discussed.
11:10	HM 23	Analysis of debinding and sintering of additive manufactured green bodies of cemented carbides Gestrich T.¹, Pötschke J.¹, Berger C.¹, Abel J.¹, Gruner D.¹, Kaiser A.¹ ¹Fraunhofer IKTS, Germany Abstract Additive Manufacturing (AM) allows the build-up of objects layer-by-layer. For cemented carbides, AM technologies are complicated and relatively new. Beside mastering additive manufacturing, debinding, outgassing and sintering of the green bodies are also of particular importance for high quality products. The green bodies produced by AM contain more complex and larger amounts of organic auxiliaries than in case of traditional production routes. The danger increases for deformation, pores, or undesirable changes in the carbon balance. Optical thermodilatometry is used to investigate the shape changes (anisotropic shrinkage) of fragile green bodies during melting and debinding of organic auxiliaries and sintering. Thermogravimetry (for investigating mass changes) combined with gas analysis (mass spectrometry and FTIR-spectroscopy) gives further insides into the nature of debinding and sintering. Phase transitions like melting of organics or metal binder phases are determined by Differential Scanning Calorimetry. The methods of thermal analysis help to understand and optimize these processes. Binder jetting, thermoplastic 3D printing and Fused Filament Fabrication (FFF) are special kinds of AM techniques which are discussed regarding differences during debinding and sintering.
11:30	HM 24	Gravitational mass flow measurements of various granular materials in relation to an extended Bond number Just M.¹, Hippe F.¹, Useldinger R.¹, Baller J.² ¹CERATIZIT Luxembourg S.à.r.l., Luxembourg ²University of Luxembourg, Luxembourg Abstract The flowability of powder-like materials is crucial for filling of cavities in the pressing process. The challenge to maintain repetitive filling of the cavity depends on the granular characteristics and pressing parameters. Commonly, microscopic powders are shaped to macroscopic spherical granules to enhance the flowability, boosting the filling behavior and favorably reduce mass fluctuations between subsequent pressing cycles. The characterization of the granules can be challenging to acquire sufficient information in relation to their flow properties. In the present study, powder and granular materials of different nature are characterized to obtain an empirical model based on the Beverloo Law to predict the granular mass flow rate. A new approach is to combine the Beverloo Law with the Bond number by considering the macroscopic friction coefficient acquired from the angle of repose (AOR) measurements. The results state a critical particle rate before jamming occurs. Furthermore, the orifice to granular size ratio as well as the intergranular friction plays an important role for larger granular systems.
11:50	HM 25	CO2 Footprint of WC: The Benefits of Recycling Karhumaa T.¹, Newman K.², Smith A.², Trasorras J.L.² ¹Tikomet Oy, Finland ²Global Tungsten and Powders Corp, USA Abstract During the past decade, countries, professional societies, and industrial companies have published plans for a carbon neutral future. As developments speed up, even relatively small private companies must reduce their CO2 emissions. Greenhouse gases result from the production of cemented carbide components, primarily due to the large amounts of energy associated with mining and concentrating tungsten ore. Recycling of cemented tungsten carbide eliminates the need for mining, thus greatly reducing the CO2 footprint of cemented carbide production. We have conducted a study of the CO2 emissions associated with the production of WC powder: 1) from W ore, 2) through chemical recycling of W scrap, and 3) via direct recycling using the Zn reclaim process. Western producers of WC with high chemical recycling levels can reduce CO2 emissions by a factor of 4, as compared to production from W ore. Direct recycling, even using energy produced from fossil fuels, results in a reduction by a factor of 30. Furthermore, direct recycling using green energy in a European plant has resulted in an almost carbon neutral process.

12:10 - 13:00		Lunch Break Location: Walter Schwarzkopf Hall

13:00 - 15:00		Hard Materials - Hardmetals and properties Location: Walter Schwarzkopf Hall Show all Abstracts Hide all Abstracts
13:00	HM 26	The effect of boron-doped cobalt additions on mechanical properties of a recycled WC-Co powder Mégret A.¹, Vitry V.¹, Delaunois F.¹ ¹University of Mons, Belgium Abstract Recycled tungsten carbide powder shows low sinterability properties at conventional sintering temperatures. To enhance mechanical properties, boron-doped cobalt powder is added during the ball milling step. Due to the formation of a eutectic between boron and cobalt, the sinterability of the powders is greatly improved, and the sintering temperature could be decreased by 100°C compared to conventional processes. The as-received recycled powder contains 7.5 wt/% cobalt. That powder has been milled with the addition of boron-doped cobalt powder cobalt beforehand doped with boron. Three powders have thus been prepared: WC-7.5(Co-B), WC-10(Co-B), and WC-15(Co-B). The sintered parts have been characterized in terms of physical and mechanical properties, and grain size distributions. The boron-doped parts showed superior mechanical properties for a lower sintering temperature than boron-free samples.
13:20	HM 27	High Entropy hard phase based hardmetals and cermets Pötschke J.¹, Vornberger A.¹, Berger L.-M.¹, Herrmann M.¹ ¹Fraunhofer IKTS, Fraunhofer Institute for Ceramic Technologies and Systems, Germany Abstract The development of high entropy alloys enables the improvement of properties of hardmetals and cermets. In recent years it was shown that also the synthesis of high entropy carbides, nitrides and even carbonitrides is possible. To investigate their use as novel high entropy hard phases (HEH) in hardmetals and cermets different high entropy carbides and high entropy carbonitrides were used in combination with cobalt and nickel binder metals. Characterization of HEH phases synthesized at temperatures up to 2200 °C was done by FE-SEM, XRD as well as microhardness measurements. Results showed that single HEH phases can be synthesized and that microhardness values in the range of 2600 HV0.5 can be reached. Characterization of HEH based hardmetals sintered at 1400 °C was carried out by FE-SEM, XRD as well as magnetic and mechanical measurements. The results show that for most compositions the HEH phase can be retained and that promising mechanical values can be achieved.
13:40	HM 28	Cemented carbides with (W,Mo)C hard phase and Ni-based binder alloys Hatzl G.¹, Fürst M.¹, Lengauer W.¹ ¹Vienna University of Technology, Austria Abstract Industrially prepared (W,Mo)C powders were employed for preparation of cemented carbides with Ni, NiFe and NiFeCr binders. Three (W,Mo)C powders, W0.91Mo0.09C (average grain size 1.2µm) and W0.76Mo0.24C (average grain sizes 1.3 and 0.5µm, respectively) were mixed with Ni, Fe and Cr3C2 powders in hardmetal drums, pressed and vacuum sintered. Repeated C doping was necessary to achieve eta-free samples. Modelling of the systems was done with ThermoCalc. All materials were characterised with respect to hardness, fracture toughness, liquid-phase-formation temperature and CO outgassing upon sintering. Comparison grades were WC alloys and alloys with 5 wt% "MoC" addition (Mo2C+C) with the same binders and (W,Mo)C-Co alloys previously investigated. Although all new materials are still under research and were only vacuum sintered, the hardness/toughness relationship of the ultra-fine (W,Mo)C-NiFeCr grade was comparable to WC-Co, other grades had slightly inferior properties as compared to (W,Mo)C-Co and WC-Co grades. In view of the potential of replacing almost 25% of W and complete replacement of Co, these materials seem to have substantial potential for tungsten consumption reduction and Co replacement.
14:00	HM 29	HV-KIC charts: connecting chemistry, microstructure and processing of cemented carbides García J.¹, Chychko A.¹, Collado Cipres V.¹, Holmström E.¹, Blomqvist A.¹ ¹AB Sandvik Coromant R&D, Sweden Abstract In this work the link between chemistry, microstructure, processing and properties of cemented carbides is described in terms of hardness-toughness correlations. The experimental information to describe the properties relationship is based on collected data published in the last 40 years. Using the WC-Co system as reference, the influence of grain growth inhibitors, the addition of cubic carbides, the substitution of cobalt and the use of fast-sintering methods is presented. The use of collected data allows for statistical analysis and comparison of different material groups and may support the design of future cemented carbides materials and property models.
14:20	HM 30	Influence of carbon content on thermal conductivity of cemented carbide with nickel based binder Ther O.¹, Lavigne O.¹, Mendez M.¹ ¹Hyperion materials and technologies, Spain Abstract Physical properties and more specifically thermal conductivity of a Ni based cemented carbide were studied in function of the carbon content. Carbon level varied from eta phase precipitation to graphite precipitation. Thermal conductivity measurements showed a steadily increase of thermal conductivity with C from 75 to 90 WmK-1 at room temperature. The effect of the C content was still significant at 300ºC from 65 to 80 WmK-1. At higher temperature the trend was less clear. WC grain size and hardness were found to be similar between samples, suggesting that the increase of thermal conductivity was not related to any WC grain growth. Typically, an increase of the order of magnitude measured would correspond to move from a medium/fine cemented carbide to a coarse one (or from an ultrafine to a medium/fine one). Thermal conductivity of pure metallic binders with several amount of carbon were measured and compared to several models to determine if the variation could be the only cause of the material thermal conductivity increase.
14:40	HM 31	Preparation of NbC and Nb(C,N) powders by carbothermal reduction Berger L.-M.¹, Conze S.¹, Pötschke J.¹ ¹Fraunhofer IKTS, Germany Abstract Following the increasing research activities on the development of high performance NbC-based hardmetals, the demand on suitable powders with defined chemistry and controlled grain size at reasonable costs is increasing. The carbothermal reduction is known as synthesis method, which allows the preparation of such powders using different oxide and carbon powders as starting materials. In this work the preparation of NbC and Nb(C,N) powders is described. The reaction mechanism was studied by using oxide/carbon blends of different ratio. Different reaction steps were observed. The nitrogen content was tailored depending on the starting powders and nitrogen content in the atmosphere, while keeping a low oxygen content (0.2-0.6 wt-%) in the powders. Lattice parameters of synthesized hard phases were determined by XRD. Powder morphology and powder grain size were found to depend on the niobium oxide used. The powders were further characterized by FE-SEM, non-metal analysis and nitrogen adsorption (BET).

15:00 - 15:20		Break Location: Walter Schwarzkopf Hall

15:20 - 17:00		Refractory Metals - Additive Manufacturing Location: Walter Schwarzkopf Hall Show all Abstracts Hide all Abstracts
15:20	RM 16	Melt pool analysis of laser powder bed fusion tungsten - Experimental and Simulation Sidambe A.¹, Fox P.¹ ¹University of Liverpool, United Kingdom Abstract Additive manufacturing has been used to study the single-track formation mechanisms of pure tungsten. A series of single-track experiments were carried out using the laser powder bed fusion process in combination with numerical simulation using OpenFOAM. Tungsten melt tracks were created with laser focus offset of 0 and 1 mm, which corresponded to a laser beam diameter (the effective Gaussian laser beam radius at which the maximum irradiance is decayed to 1/e^2 or 13.5% of the peak value) of 50 and 43 μm at the target surface, respectively. The melting of the tungsten powder was carried using a laser power of 200W and a laser speeds of 50 and 400 mm/s. The results showed that the selected parameters were able to melt the tungsten and create a strong bond on the tungsten substrate. A range of melt track widths, melt pool depths, keyhole and conduction mode formations were observed under the different linear energy densities yielded by the selected parameters. The numerical model for the tungsten laser powder bed fusion was verified by the single-track experiments.
15:40	RM 17	Additive Manufacturing of Molybdenum and Tungsten by PBF-EB Kirchner A.¹, Dorow-Gerspach D.², Pilz A.³, Klöden B.¹, Weißgärber T.¹ ¹Fraunhofer IFAM Dresden, Germany ²Forschungszentrum Jülich, Germany ³Plansee SE, Austria Abstract Refractory metals are characterized by their exceptional retention of mechanical strength at high temperatures, hard-wearing properties, and high thermal conductivity. As an alternative to the conventional powder metallurgical route, additive manufacturing by powder bed fusion is attractive for complex geometries and customized parts. At the present, the targeted applications are nuclear fusion, high-temperature synthesis, and biomedical. PBF-EB parameter sets were developed for spherical Mo and W powders and 50 µm layer thickness. Due to the combination of high melting points and thermal conductivities very high energy densities were necessary to reach high density material. The as-built microstructure is characterized by grains elongated in build direction. Due to vacuum processing the oxygen contamination is negligible. Mechanical properties as well as the cracking behavior under severe thermal shock are presented. Several thin-walled structures were fabricated and analyzed.
16:00	RM 18	Characterization of pure tantalum manufactured by Laser Powder Bed Fusion (LPBF) Oehlerking F.¹, Ohm S.¹, Stawovy M.¹ ¹H.C. Starck Solutions, USA Abstract Tantalum and its alloys are one of the refractory material groups of interest for additive manufacturing (AM), as they meet the requirements for some applications in aerospace and medical industries. The present research and development work aims to characterize the microstructure, mechanical properties, and thermal properties of additively manufactured tantalum using Laser Powder Bed Fusion technology (LPBF). Primary parameter optimization of the laser power, point distance, exposure time, and hatch distance were tested using a design of experiments to optimize the relative density of the specimens for the Laser Powder Bed Fusion (L-PBF) metal AM technology. A final parameter set was selected and produced solid and thin wall samples with >99.9% density. Using this parameter, samples were printed and tested for room temperature tensile, compression, hardness, thermal conductivity, coefficient of thermal expansion, and electron backscatter diffraction (EBSD) analysis and compared to traditionally manufactured products.
16:20	RM 19	Additive manufacturing of molybdenum and tungsten: influence of carbon addition on solidification, microstructure and properties Kaserer L.¹, Braun J.¹, Kestler H.², Schafbauer W.², Singer P.², Leichtfried G.¹ ¹University of Innsbruck, Austria ²Plansee SE, Austria Abstract Additively manufactured components of the refractory metals molybdenum and tungsten using the laser powder-bed fusion (LPBF) technology exhibit pronounced defect structures and do not achieve the properties of their powder-metallurgically produced counterparts. Due to the melt metallurgical processing of LPBF, both materials tend to form an epitaxially grown, coarse-columnar microstructure that exhibits pores and intercrystalline cracks. This work shows that an addition of 3.5 at% carbon suppresses defects and leads to the formation of a fine-grained microstructure with a cellular sub-grain structure. The driving mechanisms of solute rejection and constitutional supercooling are discussed based on experimental findings. TEM, SEM and EBSD investigations are used to prove that molybdenum and tungsten can be adapted to the LPBF process by appropriate alloy adjustments.
16:40	RM 20	Undoped and carbon-doped molybdenum manufactured by Laser Powder Bed Fusion Braun J.¹, Kaserer L.¹, Stajkovic J.¹, Kestler H.², Schafbauer W.², Singer P.², Leichtfried G.¹ ¹University of Innsbruck, Austria ²Plansee SE, Austria Abstract The defect structure of pure molybdenum manufactured by Laser Powder Bed Fusion (LPBF) at room temperature was investigated by OM of metallographic cross-sections, SEM and EDX of fracture surfaces, as well as TEM and EDX of thin sections to study grain and subgrain structures. Molybdenum samples with differing oxygen contents were produced at substrate plate temperatures of 800 °C and 1200 °C to further evaluate the defect mechanism. In addition, molybdenum doped with 0.016 wt% and 0.036 wt% carbon was manufactured by LPBF and compared with pure molybdenum regarding microstructure and bending strength. These studies revealthat oxygen contamination is responsible for the cracking and porosity of LPBF molybdenum. Process temperatures above Ductile-to-Brittle-Transition-Temperature and reducing the oxygen content of the powder reduce porosity and cracking. However, relative densities above 99 % could only be achieved with the 0.036 wt% carbon-doped molybdenum samples, with a 600 % increase in bending strength compared to pure molybdenum.

17:00 - 17:00		End of sessions Location: Walter Schwarzkopf Hall