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Lutz Michael Berger - One of the best experts on this subject based on the ideXlab platform.
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impact of al2o3 40 wt tio2 Feedstock Powder characteristics on the sprayability microstructure and mechanical properties of plasma sprayed coatings
Journal of The European Ceramic Society, 2019Co-Authors: Alexei Richter, Lutz Michael Berger, Yoo Jung Sohn, Susan Conze, Kerstin Sempf, Robert VasenAbstract:Abstract Atmospheric plasma sprayed (APS) Al2O3-TiO2 coatings have found a wide range of industrial application due to their favorable properties, combined with low costs and a high availability. However, the detailed effect of the phase composition and the element distribution of the Feedstock Powders on the coating properties and the spraying process have only crudely been investigated so far. Here the impact of aluminum titanate (Al2TiO5) on the microstructural features and mechanical properties of Al2O3-40 wt.% TiO2 APS coatings is demonstrated by investigating the detailed phase composition and the distribution of aluminum and titanium in three fused and crushed Feedstock Powders and the respective coatings. Thereby, a direct influence of Al2TiO5 content on the deposition efficiency, the porosity, the elastic modulus, and the hardness of the coatings is revealed. The results emphasize the need for a more detailed specification of commercial Al2O3-TiO2 Feedstock Powders to ensure a high reliability of the coating properties.
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influence of Feedstock Powder modification by heat treatments on the properties of aps sprayed al 2 o 3 40 tio 2 coatings
Journal of Thermal Spray Technology, 2018Co-Authors: Lutz Michael Berger, Yoo Jung Sohn, Kerstin Sempf, Robert VasenAbstract:The formation and decomposition of aluminum titanate (Al2TiO5, tialite) in Feedstock Powders and coatings of the binary Al2O3-TiO2 system are so far poorly understood. A commercial fused and crushed Al2O3-40%TiO2 Powder was selected as the Feedstock for the experimental series presented in this paper, as the composition is close to that of Al2TiO5. Part of that Powder was heat-treated in air at 1150 and 1500 °C in order to modify the phase composition, while not influencing the particle size distribution and processability. The Powders were analyzed by thermal analysis, XRD and FESEM including EDS of metallographically prepared cross sections. Only a maximum content of about 45 wt.% Al2TiO5 was possible to obtain with the heat treatment at 1500 °C due to inhomogeneous distribution of Al and Ti in the original Powder. Coatings were prepared by plasma spraying using a TriplexPro-210 (Oerlikon Metco) with Ar-H2 and Ar-He plasma gas mixtures at plasma power levels of 41 and 48 kW. Coatings were studied by XRD, SEM including EDS linescans of metallographically prepared cross sections, and microhardness HV1. With the exception of the Powder heat-treated at 1500 °C an Al2TiO5-Ti3O5 (tialite–anosovite) solid solution Al2−xTi1+xO5 instead of Al2TiO5 existed in the initial Powder and the coatings.
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influence of heat treatment on the abrasive wear resistance of a cr3c2nicr coating deposited by an ethene fuelled hvof spray process
Surface & Coatings Technology, 2016Co-Authors: Leo Janka, Jonas Norpoth, Richard Trache, Lutz Michael BergerAbstract:Abstract This work reveals the influence of heat treatments on the microstructure, mechanical properties and abrasive wear behaviour of a Cr 3 C 2 NiCr coating deposited by an ethene-fuelled high-velocity oxygen-fuel spray process using an agglomerated-and-sintered Feedstock Powder. The wear resistance of an as-sprayed and heat treated (8 h at 800 °C) coating was evaluated in low- and high-stress abrasion regimes, the latter in a temperature range up to 800 °C. Precipitation of secondary carbides from the supersaturated as-sprayed binder matrix is at the core of the observed changes in the coatings wear resistance upon heat treating. This aging process renders the binder matrix softer and more ductile, as was probed by means of nanoindentation, and thereby improves its resistance against micro-cracking which is identified as an important wear mechanism in high-stress abrasion conditions.
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application of hardmetals as thermal spray coatings
International Journal of Refractory Metals & Hard Materials, 2015Co-Authors: Lutz Michael BergerAbstract:Abstract Thermally sprayed hardmetal coatings have a typical thickness within the range 100–500 μm. Thus, thermal spray enables the functionality of hardmetals to be realized on the surface of large parts, which cannot be produced by Powder metallurgy for technical and economical reasons. This article reviews the different types of thermal spray processes, with particular focus on the high velocity HVOF and HVAF deposition techniques which are of most relevance to the application of hardmetal coatings. Feedstock Powder preparation technologies are presented. The majority of hardmetal thermal spray coatings are based either on WC or Cr3C2 or hard phases appearing as a result of their interaction. As an alternative, TiC-based compositions are most intensively studied. Thermal spraying generates significant changes in the hardmetal chemical and phase compositions between the Feedstock Powder to the sprayed coating. Coating formation and microstructures as well as selected properties, such as hardness, the effect of heat treatments and the oxidation in service, as well as corrosion resistance are discussed. As an example for wear protection applications, abrasion wear resistance is shortly discussed. This paper is a partly updated and condensed version of the chapter: “Coatings by thermal spray” in the book “Comprehensive Hard Materials”, V.K. Sarin (Editor-in-Chief) & D. Mari & L. Llanes (Vol. Ed.), Vol. 1 (pp. 471–506), Elsevier, 2014.
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comparative study of the dry sliding wear behaviour of hvof sprayed wc w cr 2c ni and wc cocr hardmetal coatings
Wear, 2014Co-Authors: Giovanni Bolelli, Lutz Michael Berger, Matteo Bonetti, Luca LusvarghiAbstract:Abstract Recent studies of HVOF-sprayed WC–(W,Cr) 2 C–Ni coatings indicated an applicability at temperatures above 600 °C. Therefore, in the present paper the dry sliding wear behaviour of coatings prepared from one selected Feedstock Powder was studied up to 750 °C and compared to a WC–10%Co–4%Cr coating as reference. Coatings were prepared onto stainless steel substrates by a liquid-fueled high velocity oxygen-fuel (HVOF) spray process. A Cr–W–Ni–C “mixed” matrix phase and chromium-rich large (W,Cr) 2 C grains were formed as a result of metallurgical reactions between the components WC, Cr 3 C 2 and Ni during spraying; therefore, the resulting coating can be better designated as WC–(W,Cr) 2 C–Ni. The dry unidirectional sliding wear behaviour of the coatings, studied according to ASTM G99 against Al 2 O 3 counterbodies at four different temperatures (25 °C, 400 °C, 600 °C, 750 °C) and at two sliding speeds, was interpreted on the basis of their microstructure, micromechanical properties and oxidation behaviour. The morphology and composition inside the wear scars were also studied by SEM and micro-Raman spectroscopy. The results show that the WC–(W,Cr) 2 C–Ni coating exhibits good wear resistance up to 750 °C, whereas WC–CoCr, in spite of its very mild wear at low temperature, suffers from catastrophic oxidation at 750 °C.
Robert Vasen - One of the best experts on this subject based on the ideXlab platform.
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impact of al2o3 40 wt tio2 Feedstock Powder characteristics on the sprayability microstructure and mechanical properties of plasma sprayed coatings
Journal of The European Ceramic Society, 2019Co-Authors: Alexei Richter, Lutz Michael Berger, Yoo Jung Sohn, Susan Conze, Kerstin Sempf, Robert VasenAbstract:Abstract Atmospheric plasma sprayed (APS) Al2O3-TiO2 coatings have found a wide range of industrial application due to their favorable properties, combined with low costs and a high availability. However, the detailed effect of the phase composition and the element distribution of the Feedstock Powders on the coating properties and the spraying process have only crudely been investigated so far. Here the impact of aluminum titanate (Al2TiO5) on the microstructural features and mechanical properties of Al2O3-40 wt.% TiO2 APS coatings is demonstrated by investigating the detailed phase composition and the distribution of aluminum and titanium in three fused and crushed Feedstock Powders and the respective coatings. Thereby, a direct influence of Al2TiO5 content on the deposition efficiency, the porosity, the elastic modulus, and the hardness of the coatings is revealed. The results emphasize the need for a more detailed specification of commercial Al2O3-TiO2 Feedstock Powders to ensure a high reliability of the coating properties.
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influence of Feedstock Powder modification by heat treatments on the properties of aps sprayed al 2 o 3 40 tio 2 coatings
Journal of Thermal Spray Technology, 2018Co-Authors: Lutz Michael Berger, Yoo Jung Sohn, Kerstin Sempf, Robert VasenAbstract:The formation and decomposition of aluminum titanate (Al2TiO5, tialite) in Feedstock Powders and coatings of the binary Al2O3-TiO2 system are so far poorly understood. A commercial fused and crushed Al2O3-40%TiO2 Powder was selected as the Feedstock for the experimental series presented in this paper, as the composition is close to that of Al2TiO5. Part of that Powder was heat-treated in air at 1150 and 1500 °C in order to modify the phase composition, while not influencing the particle size distribution and processability. The Powders were analyzed by thermal analysis, XRD and FESEM including EDS of metallographically prepared cross sections. Only a maximum content of about 45 wt.% Al2TiO5 was possible to obtain with the heat treatment at 1500 °C due to inhomogeneous distribution of Al and Ti in the original Powder. Coatings were prepared by plasma spraying using a TriplexPro-210 (Oerlikon Metco) with Ar-H2 and Ar-He plasma gas mixtures at plasma power levels of 41 and 48 kW. Coatings were studied by XRD, SEM including EDS linescans of metallographically prepared cross sections, and microhardness HV1. With the exception of the Powder heat-treated at 1500 °C an Al2TiO5-Ti3O5 (tialite–anosovite) solid solution Al2−xTi1+xO5 instead of Al2TiO5 existed in the initial Powder and the coatings.
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columnar structured thermal barrier coatings tbcs by thin film low pressure plasma spraying lpps tf
Journal of Thermal Spray Technology, 2011Co-Authors: Andreas Hospach, Georg Mauer, Robert Vasen, Detlev StöverAbstract:The very low-pressure plasma Spray (VLPPS) process has been developed with the aim of depositing uniform and thin coatings with coverage of a large area by plasma spraying. At typical pressures of 100-200 Pa, the characteristics of the plasma jet change compared to conventional low-pressure plasma-spraying processes (LPPS) operating at 5-20 kPa. The combination of plasma spraying at low pressures with enhanced electrical input power has led to the development of the LPPS-TF process (TF = thin film). At appropriate parameters, it is possible to evaporate the Powder Feedstock material providing advanced microstructures of the deposits. This technique offers new possibilities for the manufacturing of thermal barrier coatings (TBCs). Besides the material composition, the microstructure is an important key to reduce thermal conductivity and to increase strain tolerance. In this regard, columnar microstructures deposited from the vapor phase show considerable advantages. Therefore, physical vapor deposition by electron beam evaporation (EB-PVD) is applied to achieve such columnar-structured TBCs. However, the deposition rate is low, and the line-of-sight nature of the process involves specific restrictions. In this article, the deposition of TBCs by the LPPS-TF process is shown. How the evaporation of the Feedstock Powder could be improved and to what extent the deposition rates could be increased were investigated.
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columnar structured thermal barrier coatings tbcs by thin film low pressure plasma spraying lpps tf
Journal of Thermal Spray Technology, 2011Co-Authors: Andreas Hospach, Georg Mauer, Robert Vasen, Detlev StöverAbstract:The very low-pressure plasma Spray (VLPPS) process has been developed with the aim of depositing uniform and thin coatings with coverage of a large area by plasma spraying. At typical pressures of 100-200 Pa, the characteristics of the plasma jet change compared to conventional low-pressure plasma-spraying processes (LPPS) operating at 5-20 kPa. The combination of plasma spraying at low pressures with enhanced electrical input power has led to the development of the LPPS-TF process (TF = thin film). At appropriate parameters, it is possible to evaporate the Powder Feedstock material providing advanced microstructures of the deposits. This technique offers new possibilities for the manufacturing of thermal barrier coatings (TBCs). Besides the material composition, the microstructure is an important key to reduce thermal conductivity and to increase strain tolerance. In this regard, columnar microstructures deposited from the vapor phase show considerable advantages. Therefore, physical vapor deposition by electron beam evaporation (EB-PVD) is applied to achieve such columnar-structured TBCs. However, the deposition rate is low, and the line-of-sight nature of the process involves specific restrictions. In this article, the deposition of TBCs by the LPPS-TF process is shown. How the evaporation of the Feedstock Powder could be improved and to what extent the deposition rates could be increased were investigated.
Hyung-jun Kim - One of the best experts on this subject based on the ideXlab platform.
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cold spraying of al sn binary alloy coating characteristics and particle bonding features
Surface & Coatings Technology, 2008Co-Authors: Xianjin Ning, Hyung-jun Kim, Jaehoon Jang, Chang Hee LeeAbstract:Abstract In this study, Al–Sn binary alloy coatings were prepared with Al–10 wt.% Sn (Al–10Sn) and Al–20 wt.%Sn (Al–20Sn) gas atomized alloy Powders by low pressure cold spray process. The microstructure and microhardness of the coatings were characterized. The deposition efficiency of Al–Sn and pure aluminum Powder were tested on sand blasted substrates of Al6061, copper and SUS304. To investigate the particle bonding features of Al–10Sn Powder, the wipe test was carried out on polished substrate surfaces. The average critical velocity of Al–Sn alloy Powders was estimated combining with the deposition efficiency. The results proved that Al–Sn coatings with dense and uniform structure can be deposited successfully by low pressure cold spray with helium as the propellant gas. The weight content of tin in Al–Sn coating is 12% and 22% for Al–10Sn and Al–20Sn coating, respectively. With the increase of tin content in Feedstock Powder, the as-sprayed coatings present similar microhardness of 73 and 74 for Al–10Sn and Al–20Sn while, on the other hand, the deposition efficiency decreased. Bonding features of Al–10Sn particles indicated that the melting of tin phase occurred on the contact interface during particle impacting. This melting of tin phase and low strength of tin may affect the particle bonding process and hence increase the critical velocity for Al–Sn binary alloy Powders.
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the effects of Powder properties on in flight particle velocity and deposition process during low pressure cold spray process
Applied Surface Science, 2007Co-Authors: Xianjin Ning, Jaehoon Jang, Hyung-jun KimAbstract:In cold spray process, impacting velocity and critical velocity of particles dominate the deposition process and coating properties for given materials. The impacting velocity and critical velocity of particles depend on the Powder properties and cold spray conditions. In the present study, the in-flight particle velocity of copper Powder in low pressure cold spraying was measured using an imaging technique. The effects of particle size and particle morphology on in-flight particle velocity and deposition efficiency were investigated. The critical velocity of copper Powder was estimated by combining the in-flight particle velocity and deposition efficiency. The effect of annealing of Feedstock Powder on deposition and critical velocity was also investigated. The results showed that the irregular shape particle presents higher in-flight velocity than the spherical shape particle under the same condition. For irregular shape particles, the in-flight velocity decreased from 390 to 282 m/s as the particle size increases from 20 to 60 μm. Critical velocities of about 425 m/s and more than 550 m/s were estimated for the Feedstock copper Powder with spherical and irregular shape morphology, respectively. For the irregular shape particles, the critical velocity decreased from more than 550 to 460 m/s after preheating at 390 °C for 1 h. It was also found that the larger size Powder presents a lower critical velocity in this study.
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superhard nano wc 12 co coating by cold spray deposition
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2005Co-Authors: Hyung-jun Kim, Chang Hee Lee, Soon-young HwangAbstract:Abstract Processing of cermet such as WC–Co is not easy by cold spray deposition, although cold spray process can eliminate the degradation of the WC phase as compared to conventional high velocity oxygen fuel (HVOF) or plasma spraying process. In this study, WC–12%Co Powders with nano-sized WC were deposited by cold spray process using helium gas. Microstructural characterization and phase analysis of Feedstock Powders and as-deposited coatings were carried out by SEM and XRD. The results show, as expected, that there is no detrimental phase transformation and/or decarburization of WC by cold spray deposition. It is also observed that nano-sized WC in the Feedstock Powder is maintained in the cold sprayed coatings. It is demonstrated that it is possible to fabricate the nano-structured WC–Co coatings with low porosity and very high hardness (∼2050 HV) by cold spray deposition with reasonable Powder preheating.
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Fabrication of WC–Co coatings by cold spray deposition
Surface & Coatings Technology, 2004Co-Authors: Hyung-jun Kim, Chang Hee Lee, Soon-young HwangAbstract:Abstract Processing of cermet such as WC–Co is not easy by cold (gas dynamic) spraying although cold spray process can eliminate the degradation of the phase as compared to conventional high velocity oxy-fuel (HVOF) spraying process. In this study, WC–12∼17%Co Powders with nano- and microstructures were deposited by cold spray process using nitrogen and helium gases. Microstructural characterization and phase analysis of Feedstock Powders and as-deposited coatings were carried out by SEM and X-ray diffraction (XRD). The results show that there is no detrimental phase transformation and/or decarburization of WC by cold spray deposition as expected. It is also observed that nano-sized WC in the Feedstock Powder is maintained in the cold sprayed coatings. It seems that nano-sized WC is advantageous over micro-sized WC for cold spray deposition because higher particle velocity can be obtained with the same gas velocity. It is demonstrated that it is possible to fabricate the nano-structured WC–Co coating with low porosity and very high hardness (∼2050 HV) by cold spray deposition with reasonable Powder preheating.
Anne Mertens - One of the best experts on this subject based on the ideXlab platform.
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laser cladding of tic reinforced 316l stainless steel composites Feedstock Powder preparation and microstructural evaluation
Powder Technology, 2020Co-Authors: Onur Ertugrul, Tommaso Maurizi Enrici, Hakan Paydas, Enrico Saggionetto, Frederic Boschini, Anne MertensAbstract:Abstract Laser cladding was used to fabricate 316L/TiC composite coatings after optimizing the Feedstock Powder morphology. Firstly, the influences of ball-to-Powder ratio (BPR) and milling duration on the morphology were investigated. The BPR of 1: 1 and 2 h of milling was sufficient to attach considerable amount of TiC particles onto 316L particles. Then, the microstructure and hardness behaviors of 15 vol% TiC reinforced 316L coatings were examined. Partial or total dissolution of the original TiC Powders led to the formation of a reinforced austenitic microstructure with a hardness increase of 100 HV. This increase is due to a grain refinement effect of the TiC during solidification and the presence of new solidification carbides. Partially dissolved and primary MC globular carbides are well-distributed in the matrix together with few larger MC globular carbides. Furthermore, MC coral-like pseudo-primary carbides and MC branched eutectic carbides are observed inside the cells and in intercellular spaces, respectively.
Wuha Liu - One of the best experts on this subject based on the ideXlab platform.
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enhancement of wear and corrosion resistance of iron based hard coatings deposited by high velocity oxygen fuel hvof thermal spraying
Surface & Coatings Technology, 2014Co-Authors: Wuha Liu, Fuhsheng Shieu, Weitie HsiaoAbstract:Abstract Fe-based alloy material is widely used in the corrosive environment of seawater. It is replacing expensive cobalt and nickel-based alloys. Amorphous iron-based (Fe-based) alloy coatings can be deposited on stainless steel by high-velocity oxygen fuel (HVOF) thermal spraying. Following spraying, coatings were heat-treated at 500, 600, 700, 800, and 900 °C for up to three hours in a vacuum furnace. The microstructures of such coatings were analyzed herein using an optical microscope (OM) and scanning electron microscope (SEM) to monitor the morphologies of both Powders and coatings of Fe-based alloy. Phase analysis was performed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The goal of this work on the modification of Fe-based alloy Feedstock Powder is to enhance the corrosion and wear properties of these coatings. The results of this investigation reveal that adding a cobalt material to Fe-based alloy yields coatings with enhanced corrosion and tribological characteristics.
