bluuebunny/crossref_metadata_2025_split huggingface dataset:
Increase in Surface Strength by Hammering and Solid Rolling of Volumes Produced by Means of Extreme High-Speed Laser Material Deposition
Authors: Koß S. , Sayk L. , Krull C. , Reiff L. , Krupp U. , Schleifenbaum J. H. 
Published: September 2022

Abstract
In the field of additive manufacturing, the demand for Extreme High-Speed Laser Material Deposition (EHLA) is increasing due to its unique process characteristics, economic efficiency as well as its great resource efficiency. The process is currently mostly used for surface functionalization through coating, by means of corrosion and wear protection. Thereby, almost all materials can be processed and nearly all material combinations can be created. The layers produced are dense and metallurgical bonded, and furthermore the surface roughness produced is low, so that only 20-100 μm has to be removed to produce a finished surface. However, it can also be used for the generation of 3D geometries. The greatest cost factor in the production is the coating material. With increasing requirements, for example in wear protection, cost-intensive special alloys or materials must be used. An opportunity to increase the areas of application in the field of wear resistance as well as increasing material efficiency is offered by combining EHLA with the innovative post-processing methods of hammering, solid as well as smooth rolling. Using these processes, the surface roughness can be reduced to a value of Rz 1-3 μm on the one hand and the surface hardness can be increased on the other hand. The hammering and solid rolling processes differ in their depth of impact. In the case of hammering, the impact depth can be a few millimeters and in the case of solid rolling only a few tenths of a millimeter. So far, the influence of hammering or solid rolling of additive manufactured volumes or surfaces has not been investigated. In the context of this study, the influence of hammering and solid rolling on a volume produced with EHLA is investigated. For this purpose, an EHLA produced volume of IN718 is built up and the influence of hammering as well as solid rolling on the surface roughness and hardness is analyzed.
Cold Spray Nozzle Design for Deposition of Adhesive Perfluoroalkoxy Alkane as an Icephobic Coating
Authors: Leclerc Z. , McMunn L. E. , Ben R. N. , Jodoin B. 
Published: September 2022

Abstract
The development of efficient ice mitigation systems for surfaces exposed to atmospheric ice has been in progress for decades. The need for passive anti-icing systems is essential as current ice mitigation systems require a substantial amount of energy and their implementation involves complex manufacturing considerations. Fluorinated polymer coatings are among the candidates for passive anti-icing systems. While many processes have been investigated to produce them, these methods can be costly, time consuming and can cause thermal damage to the substrate. The current work aims to explore a green and cheap alternative approach by using cold spray. Furthermore, the cold spray process offers advantages such as being a portable easy to perform solid-state coating process for eventual repairs. This work uses computational and experimental approaches to design and test a new dedicated nozzle for the efficient deposition of adhesive perfluoroalkoxy alkane. Computational results reveal that for the same operating conditions, the use of the new nozzle design increases particle impact temperature, improving the deposition of the feedstock material, as confirmed experimentally. The wetting behaviour, ice nucleation time and ice adhesion strength were compared for 6 different surface types, including bare aluminum, various polymer materials and the cold spray perfluoroalkoxy alkane coating on aluminium substrate. Results indicate that the as-sprayed coating performs as both a superhydrophobic and icephobic surface.
The Stimulation of Grain Structure Evolution in Aluminium Cold Spray by Monte Carlo Method
Authors: Yu P. , Yin S. , Lupoi R. 
Published: September 2022

Abstract
Cold spray (CS), a solid-state depositing technique, has recently demonstrated promising application in additive manufacture (AM). Compared with fusion based AM technique, cold spray can eliminate solidification defects and is appropriate to fabricate some materials that are difficult for high energy beam methods, such as Aluminium. In the cold spray process, extreme plastic deformation will occur, which triggers the severe dynamic recrystallization and result in the formation of ultrafine grain structure. For a dense CSed component, the grain structure highly influences its performance. Especially for the grain structure in the region around the impact interface, which decides the bonding of particles. However, due to the extreme processing condition of CS and complicated deformation history around the interface, it is challenging to carryout systematic study on the factors that influence the finial grain structure and make a prediction on the final grain size in this region. Here, a Monte Carlo model was built to simulate the dynamic recrystallization in the Aluminium cold spray process. The influence of impact velocity and single/multiparticle impact on the final grain structure in the interface was investigated comprehensively and independently. And the average grain size on the impact interface predicted by the modelling agreed well with reported experimental results.
Nitriding Effect on HVAF FeMnCrSi Coating
Authors: Rafael de Oliveira W. , Renan Mayer A. , Marenda Pukasiewicz A. G. , Biscaia de Souza G. 
Published: September 2022

Abstract
Thermochemical processes are an appropriate way to improve the surface hardening of the material against wear. Thermal spraying is a group of deposition processes that can deposit different classes of materials. The use of thermomechanical process after metallic coatings deposition can result in a unique combination of bulk and surface properties. There are some studies that indicate the defects and stresses caused in the crystal lattice as one of the factors that most influence nitrogen diffusion during the nitriding process. The HVAF (High Velocity Air-Fuel) process can generate different fault conditions and stress-strain in the crystal lattice. The aim of this work is study the effect of the plasma nitriding or, as it is known, Glow Discharge (GD), on FeMnCrSiNi coating deposited with HVAF process. Initially, it was observed the formation of expanded austenite and CrN on the HVAF coating, followed by important increase on the hardness of the coating.
Exploring Miniaturized HVOF Systems for the Deposition and Near Net Shape Forming of Ti-6Al-4V
Authors: Oberste-Berghaus J. , Aghasibeig M. , Burgess A. , Khamsepour P. , Moreau C. , Dolatabadi A. 
Published: September 2022

Abstract
The exceptional properties of Ti-6Al-4V of high strength, lightweight, corrosion resistance and machinability make it one of the most widely used alloys in in the aerospace industry. Significant efforts are underway to establish powder bed additive manufacturing (AM) technologies for Ti-6Al-4V. There are also increasing attempts to use thermal and cold spray to build near net shape parts with buildup rates orders of magnitude higher than powder bed. Thermal spraying, such as HVOF, can oxidize and degrade the alloy due to the high processing temperature. Lowering the flame temperature through inert gas addition in full-size HVOF systems is a possible approach to retain solid state deposition of the feedstock particles, thereby limiting oxidation and detrimental α-case formation, while providing sufficient heat input for particle softening and plastic deformation at impact. Novel miniaturized HVOF systems, with spray jets of only a few millimetre in width, may further offer the possibility to improve the spatial resolution of the buildup for near net shape forming. The process parameter range for solid state deposition of Ti-6A-4V, using the liquid fuelled TAFA Model 825 JPid and the novel hydrogen fuelled Spraywerx ID-NOVA MK-6 with the addition of nitrogen will be discussed. Build-ups at over 80% deposition efficiency generally yield as-sprayed porosities below 3% and hardness above 200 HV100gf. Attainable microstructures and oxygen content as a function of spray parameters are delineated. Recrystallization and beta annealing of selected samples lowered the residual porosity and created equiaxed α and intergranular ß-phases. Ultimate tensile strengths of up to 1100 MPa were attained, however, at limited elongation.
Modeling Study on Stress Distribution at MCrAlY-YSZ Interface Influenced by Pores and Micro Bulges
Authors: Xu Z. , Wen J.-F. , Yuan K. 
Published: September 2022

Abstract
During the thermal cycling process in MCrAlY-YSZ thermal barrier coating system, stresses are produced at bondcoat (BC)-topcoat (TC) interface due to the mismatch of the thermal expansion coefficients of the two coating layers. The stresses at the interface are not a single value and can be affected by the coatings’ microstructure. In this paper, finite element (FE) modeling method was used to study the behavior of the stress distribution at the coatings’ interface. The influence of the pore structure in the ceramic TC and the micro bulge structure at the metal BC surface was investigated. The results showed that both structures can change the stress distribution. The pores played a “stone-in-river” role, which trapped higher stress around them and simultaneously reduced the size of the macro stress zones in TC. The micro bulges at the TC/BC interface also trapped high stresses which could cause more interaction between TC cracks and BC roughness.
Gain Insight About Thermal Spray Processes using Artificial Intelligence and Big Data Analysis
Authors: Fassl L. , Nabavi M. , Schwenk A. 
Published: September 2022

Abstract
Thermal spraying is a complex physical process consisting of three main sub-systems: flame/plume generation, powder/flame/plume interaction and coating build-up. While mathematical and CFD models provide valuable insight about the individual modules of a thermal spray process, it is very difficult to gain overall insight of the whole process and dependencies between different inputs and outputs using mathematical and CFD analysis, due to very complex and interconnected nature of the thermal spray process. In this work, a sophisticated experiment has been conducted to collect enough data for the sake of developing data-driven model of a plasma spray process. Metco 204 powder feedstock material and F4 gun have been used. An optimized number of data samples has been chosen by applying common industrial input parameters in the experiment. The developed neural network model is able to predict the coating quality parameters with acceptable average accuracy of above 90% on test data by considering all relevant measurement error deviations of the process analysis methods. A sophisticated user-interface has been developed to enable the use of the model for coating parameter development as well as the designing recipe for target coating characteristics. The developed model can be used for different purposes: parameter development, off-line coating quality control, and eventually adaptive coating control.
Numerical Investigation of the Effect of a Nozzle Extension on the Plasma Jet
Authors: Bobzin K. , Heinemann H. , Dokhanchi S. R. 
Published: September 2022

Abstract
In plasma spraying, compared to other thermal spraying process variants, only a small part of the available energy is used to build up a coating. Another peculiarity of this process is the relatively strong oxidation of the sprayed metallic particles, caused by the high temperatures and turbulent flow of the plasma jet in combination with the ambient air. A promising solution for increasing energy efficiency is a solid shroud that surrounds the plasma jet and thus prevents air entrainments from mixing with the plasma gas. The primary goal of this study is to develop a numerical model to investigate the effect of an external fixed nozzle extension on the plasma jet as a shroud. To this end, the existing simulation models of the plasma jet from the previous works of the authors were extended to model a solid nozzle extension at the outlet of a three-arc plasma generator. Furthermore, the length and diameter of the nozzle extension were parametrized to investigate their effects on the plasma temperature and the turbulence of the flow. This model can be used to optimize the geometry of the nozzle extension based on experimental measurements to adapt it to the flow conditions of the plasma jet. The results revealed that the plasma temperature could be increased using the nozzle extension, thereby raising the energy efficiency to melt the particles in plasma spraying.
Effect of Cathode-Plasma Coupling on Plasma Torch Operation Predicted by a 3D Two-Temperature Electric Arc Model
Authors: Zhukovskii R. , Chazelas C. , Rat V. , Vardelle A. , Molz R. 
Published: September 2022

Abstract
In a DC plasma spray torch, the plasma-forming gas is the most intensively heated and accelerated at the cathode arc attachment due to the very high electric current density at this location. A proper prediction of the cathode arc attachment is, therefore, essential for understanding the plasma jet formation and cathode operation. However, numerical studies of the cathode arc attachment mostly deal with transferred arcs or conventional plasma torches with tapered cathodes. In this study, a 3-D time-dependent and two-temperature model of electric arc combined with a cathode sheath model is applied to the commercial cascaded-anode plasma torch SinplexPro. The model is used to investigate the effect of the cathode sheath model and bidirectional cathode-plasma coupling on the predicted cathode arc attachment and plasma flow. The model of the plasma-cathode interface takes into account the non-equilibrium spacecharge sheath to establish the thermal and electric current balance at the interface. The radial profiles of cathode sheath parameters (voltage drop, electron temperature at the interface, Schottky reduction of the work function) were computed on the surface of the cathode tip and used at the cathode-plasma interface in the model of plasma torch operation. The latter is developed in the open-source CFD software Code_Saturne. It makes it possible to calculate the flow fields inside and outside the plasma torch as well as the enthalpy and electromagnetic fields in the gas phase and electrodes. This study shows that the cathode sheath model results in a higher constriction of the cathode arc attachment, more plausible cathode surface temperature distribution, more reliable prediction of the torch voltage, cooling loss, and more consistent thermal balance in the torch.
Cavitation Erosion in WC-10Co-4Cr Coating
Authors: Algoburi A. , Ahmed R. , Nazarinia M. 
Published: September 2022

Abstract
This paper evaluates the cavitation erosion wear rate and failure modes of WC-10Co-4Cr coatings. These coatings are used in various industrial applications to protect against erosive, abrasive, sliding and cavitation wear in corrosive environments. Cavitation erosion tests were performed using a modified ASTM G-32 cavitation test rig. Thermally sprayed High Velocity Oxy-Fuel (HVOF) WC-Co-Cr coatings were deposited using industrially optimised coating process parameters on carbon steel and stainless-steel substrate coupons. Coatings were tested to simulate the cavitation bubbles occurring in valves, pumps, and ship propellers. Indirect cavitation was used to impact the cavitation bubbles on the test specimen at a fixed offset distance from the vibrator end. Test specimens were immersed in natural seawater. A water circulation cooling system was used to control the temperature of the water. The cumulative mass cavitation erosion and erosion rate results were evaluated. The coating microstructure was analysed using Scanning Electron Microscopy (SEM) and x-ray diffraction. Post-test evaluations included SEM observation in combination with energy dispersive x-ray analysis (EDX) to understand the failure modes. Results are discussed in terms of the factors controlling the cavitation erosion rate.
On the Applicability of Iron-Based Alloy Coatings to Different Wear Conditions
Authors: Varis T. , Lagerbom J. , Suhonen T. , Terho S. , Laurila J. , Vuoristo P. 
Published: September 2022

Abstract
Iron-based coatings are often considered as replacement of hard chromium and WC-Co, as they pose lower health and environmental impact. In many cases the combination of mechanical and chemical properties of ferrous based alloys may be satisfactory and their relatively low cost make these coatings an interesting candidate for many applications. This study is inspired by opportunities to harden the ferrous base materials by strain hardening, solid solution strengthening, dispersion strengthening, and precipitation hardening. Already commercially available Fe-based coating materials with precipitates of mixed carbides and borides in the metastable austenitic matrix achieve a high hardness. In this study the cavitation erosion and abrasion resistance of various Fe-based coatings produced by HVAF and HVOF processes were investigated. Two experimental precipitation containing materials were prepared, and the sprayed coatings were tested for abrasive and cavitation erosion wear. In addition to precipitations, the importance of proportion of ferrite and retained austenite phases were studied by affecting the microstructure by heat treatments as the ability of different phases to affect hardening and ductility may become crucial in generating desired material properties. The properties of experimental and some commercial Fe-based alloys are compared with WC-Co and Cr3C2-NiCr coatings by property mapping.
Flame-Sprayed NiCoCrAlTaY Coatings as Damage Detection Sensors
Authors: Ogunbadejo A. S. , McDonald A. , Chandra S. 
Published: September 2022

Abstract
The piezoresistivity of flame-sprayed NiCoCrAlTaY on an electrically insulated surface of a steel substrate was investigated through cyclic extension and compression cycles between 0 and 0.4 mm for 1000 cycles and uniaxial tensile test. The sprayed NiCoCrAlTaY was in grid form with grid thickness of 3 mm and grid length of 30 mm while the electrical insulation was fabricated by flame spraying alumina on the surface of the steel. During mechanical loading, instantaneous electrical resistance measurements were conducted to evaluate the corresponding relative resistance change. Images of the loaded samples were captured for strain calculations through Digital Image Correlation (DIC) technique. After consolidation of the pores within the coating, the behavior of the flame-sprayed NiCoCrAlTaY was consistent and linear within the cyclic compression and extension limits, with strain values of approximately -1000 με and +1700 με, respectively. The coating had a consistent and steady maximum relative resistance change of approximately 5% within both limits. The tensile test revealed that the coating has two gauge factors due to the bi-linearity of the plot of relative resistance change against strain. The progression of damage within the coating layers was analyzed from its piezoresistive response and through back-scattered scanning electron microscopy images. Based on the results, the nickel alloy showed high piezoresistive sensitivity for the duration of the loading cycles, with little or no damage to the coating layers. These results suggest that the flame-sprayed nickel alloy coating has great potential as a surface damage detection sensor.
HVSFS Al2O3-TiO2 Coatings of Porous Aluminium Substrates
Authors: Sauter M. , Martínez García V. , Killinger A. 
Published: September 2022

Abstract
In a novel approach for guiding elements of sawing machines wear resistant coatings were applied on open-porous AlSi7Mg substrates by means of high velocity suspension flame spraying (HVSFS). The challenge is to establish a wear resistant coating but simultaneously maintain the open-porous structure that is necessary to serve as a permeable structure for liquid cooling or lubricant media under operation. In a first approach, a water-based suspension containing a mixed Al2O3-TiO2 powder for HVSFS was used to deposit dense and well adherent mixed-oxide coatings. As the substrates exhibit an open-porous structure and a well-defined pore size distribution, transpiration cooling through the pores is possible and even necessary in order to ensure a low thermal impact on the fragile pore structure, preserving the open-porosity of the substrate. The coatings are characterized and compared by the means of light microscopy and hardness indentation.
Hybrid Aerosol Deposition as an Outstanding Prospective for Dense Barrier Ceramic Coatings Deposition on Different Substrates
Authors: Shahien M. , Shinoda K. , Akedo J. 
Published: September 2022

Abstract
Deposition of protective dense environmental barrier layers is a promising solution to improve the reliability and environmental durability of the next-generation turbines and other industrial applications. In this context, spraying of fine particles could enhance the formation of fine dense coating microstructures with improved properties. In AIST we are focusing on the spraying of the fine particles via different spraying technologies including suspension plasma spraying, as well as deposition of the fine solid particles directly by aerosol deposition (AD) and plasma-assisted aerosol deposition (so-called Hybrid Aerosol Deposition; HAD. The HAD is a new coating window to spray the fine ceramic particles via the implementation of a low-power rf-plasma source to assist the aerosol deposition at room temperature. This study introduced the feasibility of utilization of HAD as an outstanding technology for deposition of dense ceramic coatings on different substrate materials and 3D deposition capability. Highly dense and well-adhered Al2O3 coatings without obvious observable cracks and bulk-like properties were successfully fabricated on different substrate materials of SUS 304, Aluminium, Al2O3 and glass, via HAD of fine particles. The substrate material and its hardness significantly influenced the first deposition step, which determined the coating adhesion and properties. Furthermore, homogeneously uniform, dense, and crack-free coating with a strong adhesion has been fabricated successfully on cylindrical substrates with 6.3 mm diameter. During HAD spraying the plasma activated the surface of the particles without reaching to the molten state, then the activated particles impact and stuck with the substrate by room temperature impact consolidation mechanism. Therefore, the fabricated coatings had the same crystal structure as the starting feedstock powder, and the activated surface act as glue and improved the deposition efficiency and 3D capabilities. Herein, the deposition phenomena of HAD makes it as a promising candidate technology for development of environmental and sealing layers of highly dense microstructure, with the targeted crystalline phase structure, without stoichiometric composition nor phase transformation and improved deposition efficiency on multi-shape components in different fields such as environmental, thermal barrier coatings (TBCs), environmental barrier coatings (EBCs) and gas turbine applications.