bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of Near Net Shaped Coatings for Reduced Postprocessing Costs in Valves
Authors: Bobzin K. , Wietheger W. , Burbaum E. , Schulz M. 
Published: September 2022

Abstract
Thermally sprayed WC/CoCr coatings are established in the valve industry for wear protection. However, conventional coatings have to be cost-intensively postprocessed. Therefore, the aim of this study is to develop near net shaped (nns) WC/CoCr-coatings with a high wear resistance in order to avoid the expensive grinding postprocess. For the development of the nns coatings a parameter study is used to investigate the influence of the stand-off distance and hydrogen volume flow rate in the HVAF process. The parameter study indicates the influence of the hydrogen volume flow and the stand-off distance on the porosity, microhardness and wear resistance of the coatings. The developed coatings exhibit a low porosity and high wear resistance. Through the correlation of the coating properties with the process parameters, promising parameter ranges for a further development of HVAF-sprayed nns coatings of WC/CoCr can be identified. With these results, first benchmarks for HVAF process parameters, hydrogen flow rate and stand-off distance, could be delivered, advancing the overall goal of reducing manufacturing costs of valves.
Cold Spray of Hydroxyapatite Coatings: Interest of PEEK as an Intermediate Layer
Authors: Chatelain D. , Denoirjean A. , Guipont V. , Rossignol F. , Tessier-Doyen N. 
Published: September 2022

Abstract
In the last 15 years, the cold spray process has demonstrated a great efficiency for the deposition of metallic powders. In this case, the consolidation of coatings is achieved thanks to the high kinetic energy of unmelted particles exhibiting a ductile behaviour. Dealing with ceramics, cold spray is also of great interest because one can expect properties not reachable with classical thermal spray technologies thanks to lower involved temperatures. However, cold spray of ceramics still remains challenging because of the ceramics intrinsic brittleness. Here, in the specific case of hydroxyapatite and to overcome this brittleness issue, we investigate the role of an intermediate PEEK layer between the substrate and the deposit. We highlight how this sublayer previously deposited by FS or air APS spraying can help improving the consolidation of the coating and its growth.
Production of Titanium Dioxide with Optimum Heterojunctions and Coating Production via Cold Spray
Authors: Hawkins A. , Guo D. , Steeves A. , Variola F. , Jodoin B. 
Published: September 2022

Abstract
Titanium dioxide (TiO2) coatings possess high appeal due to self-cleaning properties that can accelerate decomposition of organic pollutants. The global objective is to develop a cold sprayable feedstock powder with an outer titanium dioxide shell that maximises anatase-rutile heterojunctions for enhanced photocatalytic activity under ultraviolet light and the development of cold spray process parameters for successful deposition of this powder into thin photocatalytic coatings. The objective of this reported first step of our global research effort to produce superior photocatalytic TiO2 coatings by cold spray is to successfully engineer anatase and rutile nanostructure heterojunction shells on pure titanium (CP-Ti) powder known to be easily sprayable by cold spray and then verify its photocatalytic properties through exposure to an organic pollutant, methylene blue (MB). Anatase and rutile heterojunctions are desired due to high activity, stability and broadened bandwidth as opposed to each singular nanostructure. The resulting powder coming out of this first step was characterized using Raman spectroscopy to verify the presence of the desired heterojunctions. The photocatalytic reactivity was tested and evaluated through the degradation of methylene blue upon contact with the TiO2 powder. Results of this first step showed growth of desired heterojunctions and high reactivity of the produced powder.
Investigation of Novel Nano-Carbide WC/CoCr Coatings Applied by HVAF
Authors: Bobzin K. , Wietheger W. , Burbaum E. , Johann L. M. , Rempe L. J. , Matikainen V. , Kanerva U. , Karhu M. , Lagerbom J. , Kaunisto K. , Lartigue J.-F. 
Published: September 2022

Abstract
Wear leads to high material and energy losses in various industries. The manufacturing of novel nano-carbide WC/Co powder feedstock materials promises a further increase in the performance of thermally sprayed wear protection coatings. A novel experimental powder and a commercial ultra-fine carbide WC/CoCr reference are thermally sprayed onto a 1.0038 substrate by High Velocity Air Fuel (HVAF) spraying. The specimens are metallographically prepared and analyzed by means of light microscopy (LM) and scanning electron microscopy (SEM). Vickers Hardness testing is conducted by microindentation and the porosities are determined by optical image analysis. X-ray diffractometry (XRD) analysis are used to investigate the phase retention. Fine nanocrystalline WC-structures are preserved in the dense coatings. A significant effect of powder type on the porosity of the coating was found. No systematic relationships could be identified between the coating structure and the parameter settings. It was possible to influence decarburization via both the powder type and the selected parameters. The resulting experimental coatings exhibit high hardness values in the range of the commercial ultrafine carbide WC reference. The novel nano-structured coating can contribute to reduced wear and therefore improve the efficient utilization of critical raw materials like tungsten.
Wear Resistant Nano-Carbide WC-CoCr Coating by Novel Powder Manufacturing Method
Authors: Matikainen V. , Lagerbom J. , Kaunisto K. , Heino V. , Bobzin K. , Wietheger W. , Burbaum E. , Johann L. M. , Lartigue J.-F. , Kanerva U. , Karhu M. 
Published: September 2022

Abstract
Surface quality lifetime and wear resistance of protective coatings can be improved by decreasing carbide grain size from submicron to nanoscale. In this study, experimental WC-CoCr powders were manufactured via novel powder manufacturing approach using water-soluble raw materials. Produced powders were sprayed with the High-Velocity Air-Fuel (HVAF) spray process to control the particle temperature and to avoid in-flight decomposition of the nanocarbides. As a result, dense and wear resistant coatings with nanosized carbides were produced. Reference coatings were sprayed using commercial sub-micron WC-CoCr powder to compare the properties of the experimental coatings to the current state-of-the-art. Phase composition and microstructural characterization of the coatings were carried out with X-ray diffraction and electron microscopy, respectively. Mechanical properties were studied by using microhardness tester, as well as rubber wheel abrasion and cavitation erosion wear tests. The wear surfaces were characterized after the abrasion and cavitation erosion tests to understand the effect of nano-carbides on degradation mechanisms. Coatings with the nanosized carbides in the structure showed excellent mechanical properties in wear testing, and even outperformed reference coatings in cavitation erosion test. Based on the obtained results, these novel nano-carbide coatings are promising alternatives for demanding applications in which better surface quality lifetime is vital.
Suspension Sprayed Thin Metallic Coatings for Electric Panel Heaters
Authors: Kummer H. , Winkelmann M. , Wüst F. , Hartmann S. , Trenkle F. , Krieg P. , Killinger A. 
Published: September 2022

Abstract
The use of suspensions in the thermal spraying process, makes it possible to apply sufficiently thin (&lt;30 μm), metallic coatings made of nickel-chromium alloy 2.4869 (NiCr8020). High velocity oxy-fuel suspension flame spraying (HVSFS) is used to manufacture these thin metallic coatings in order to be able to effectively use them as electric panel heaters. Area heating capacities of 25 W cm-2 are possible with them and heating rates of 15 K s-1 even outperform many ceramic heating elements. In addition, it provides a flexible way to apply the heating coatings directly to the components to be heated. The use of fine powders in the micron and sub-micron ranges allows a more precise adjustment of the coating thickness, compared to conventional thermal spraying techniques, even in the thickness range below 10 μm. Therefore, an adaption to customer needs is possible regarding the electric panel heater characteristics, like electric resistance, applied voltages and current range and heating rates.
Refurbishment of Damaged Railway Material by Cold Spray
Authors: Delloro F. , Tebib M. , Lesage T. 
Published: September 2022

Abstract
The health of railway material is of paramount importance for the safety of rail transportation. Railways are subject to heavy mechanical loading and to harsh environments, causing corrosion and damage that can bring to failure. The cold spray process has a great potential as an efficient and portable refurbishment technology, with the advantage of avoiding thermal effects on the substrate. In this study, a proof of concept for the cold spraying of railway steel onto a similar material is presented. This represents a first step towards the development of a cold spray solution for railway repair. First, the as-atomized steel powder revealed to be hardly sprayable. A heat treatment was then optimized and applied to the powder to induce microstructural evolution and to improve deposition efficiency and material quality. Therefore, the refurbishment of damaged railway samples by cold spray was proven to be viable. Finally, mechanical testing assessed the restoration of the structural properties needed for the application.
Metal Knitting: A Method to Control Morphology and Properties in Cold Spray Additive Manufacturing
Authors: Váz R. F. , Canales H. , Sanchez J. , Ocaña U. , Albaladejo V. , Garcia Cano I. 
Published: September 2022

Abstract
Cold Spraying (CS) is a thermal spray process capable of producing dense and thick coatings by the spraying of powders under high velocity and relatively low temperature. The high deposition efficiency and the thickness of each pass make possible the use of CS to produce freestanding parts, as an additive manufacturing process (CSAM). Traditionally, CS is performed spraying perpendicularly to the substrate, which ensures maximum deposition efficiency among other benefits. This, however, presents two main disadvantages for CSAM. First, by keeping the spraying angle constant, there is not much control on the final geometry of the part being built, and, second, the resultant part’s properties show anisotropy depending on whether this property is measured along the spraying axe or not. In this work, we present a method (Metal Knitting) that aims to help reduce both disadvantages. Metal Knitting is based on the performance of certain spraying movements that build near squared shapes step-by-step like in a knitting process. The principle of the method and examples are presented in this work, as well as some results on the anisotropy of 316L stainless steel freeform parts obtained by CSAM, measuring the tensile stress, hardness, and evaluating the microstructure in different directions of the material. The effect of annealing on the material properties is also investigated.
Assessment of Agglomerated Ceramic Powders Under Impact by Cold Spraying
Authors: Celeste G. , Guipont V. , Missoum-Benziane D. , Kermouche G. , Sao-Joao S. , Girard-Insardi S. , Chatelain D. 
Published: September 2022

Abstract
Most of ductile metals can be deposited by cold spray (CS). For brittle ceramic, such solid-state deposition process is still questionable, but some recent work on Ti02 or hydroxyapatite powders have shown that micrometric ceramic powder could be deposited by CS. In this work, it is claimed that the nature and the porous architecture of a ceramic powder with agglomerated ultra-fine grains play an important role on the impact behaviour. The aim of this work is to investigate the deformation behaviour of ceramic agglomerated powders under high velocity impact. Two different powders, respectively 3YSZ and Y2O3, were selected in order to study their architectures (particle size, porosity, density, crystallite size, etc.). Cold spray “splats” experiments, with various spraying distances to vary the particles velocities upon impact, were carried out to observe the deformation and fragmentation. In case of Y2O3, cold spray with dynamic vacuum surrounding atmosphere up to 3kPa were also prepared to evaluate the role of the atmosphere on the resulting impact. In parallel, in situ SEM micro-compression tests at 10−2 s−1 on cross-sectioned 3YSZ particles involving flat-punch nano-indentation and micropillar compression were performed. By modelling the compression tests, the aim is to identify a Drücker-Prager behaviour law suitable for an agglomerated ceramic powder under quasi-static compression. Such deformation behaviour could help to better understand the compaction behaviour of agglomerated powders.
Particle Acceleration Through Coaxial Co-Flow Nozzles for Cold Spray Applications
Authors: Sharma A. K. , Vashishtha A. , Callaghan D. , Nolan C. , Bakshi S. , Kamaraj M. , Raghavendra R. 
Published: September 2022

Abstract
The present study numerically investigates the effectiveness of co-flowing nozzles for cold spray applications. A convergent-divergent axi-symmetric nozzle system was simulated with high-pressure nitrogen flow. The particle acceleration is modelled by a two-way Lagrangian approach and validated with reference to experimental values reported in the literature. An annular co-flowing nozzle with circular central nozzle was simulated for nitrogen gas flow. The momentum preservation for central nozzle flow was observed, which results in higher particle speed for longer axial distance after nozzle exit. It is envisioned from the outcome that utilization of co-flow can lead to reduction in the divergent section length of cold spray central nozzles, which may ultimately help to address clogging issues for continuous operation. Co-flow operating at 3 MPa, same as with a central nozzle, can increase supersonic core length up to 23.8%.
Systematic Study of the Effects of Powder Preconditioning on Flowability and Deposition in Polymer Cold Spray
Authors: Brennan D. A. , Bacha T. W. , Tiitma Ü. , Haas F. M. , Stanzione J. F. 
Published: September 2022

Abstract
The cold spray process is sensitive to variations in feedstock and requires consistent powder properties, particularly flowability, to produce uniform structures. Poor powder flow causes a cascade of effects arising from erratic feeding including deposits with void spaces and inconsistent geometries. These issues result in deposits which are not suitable for testing and prevent sample replication, hindering experimental evaluation of deposits. Powder flowability is largely affected by the material preconditioning and storage conditions; with flowability directly affecting the deposit properties of deposition efficiency (DE), porosity, and surface finish. In this study, the flowability and deposit quality of a fluoropolymer-based powder was evaluated with changing pretreatment conditions. Powder flowability was analyzed by mass flowrate (g/s), the Carr angle of repose, and the Hausner ratio. Flowability was evaluated for powders as received, after sieving (45-100 μm), with drying at elevated temperature (80 °C), with inert gas vacuum purging, and after 72 hrs. of exposure to high relative humidity (95% RH). Powders exposed to humid conditions were also dried under inert gas vacuum purging to determine the effectiveness of the process as a reconditioning method. Preconditioned powders with the highest flowability according to these tests were sealed in metal containers, stored under 95% RH for one week, and reevaluated to determine the ability of this preconditioning and storage method to protect materials from exposure to undesirable conditions. Next, the effect of preconditioning on cold spray deposit quality was evaluated for the fluoropolymer-based powder with the best and worst flowability. The choice of spray conditions was informed by simulation of particle velocity and temperature distribution at impact using one-dimensional compressible flow modeling, couple with thermal analysis of the powder. The DE was determined gravimetrically, surface roughness was evaluated using a profilometer, and microstructure was evaluated using a scanning electron microscope (SEM). The ability to manipulate powder flowability through simple preconditioning methods and quickly evaluate the properties of the feedstock before use in the manufacturing process, coupled with straightforward and rapid evaluation the resultant deposit; will save time and money, and accelerate research efforts, compared to evaluating powder suitability by trial and error.
Ultrasonic Atomization as an Alternative Route for Metal Powder Production
Authors: Sokołowski P. , Kustroń P. , Korzeniowski M. , Sajbura A. , Piwowaczyk T. , Szostak-Staropiętka R. , Kiełbasiśnki R. 
Published: September 2022

Abstract
The use of metal powders is dynamically increasing in many different fields of research and industry. The development of additive manufacturing technology or innovative thermal spray processes still enhance the range of possible applications. This means that there is a big demand for high quality metal powder materials. Currently, the atomization methods, like water or gas atomization, seem to be most established technologies for metal powder production. This work concerns the development of an innovative technology of metal powder manufacturing, namely ultrasonic atomization. First, the general idea of ultrasonic atomization is discussed. The designing of sonotrode, in order to generate appropriate ultrasonic field responsible for metal stream atomization, is discussed. Then, the ultrasonic set-up was verified by using non-contact fiber optic displacement sensor. Finally, the developed system was preliminary tested under water loading and confirmed positively in terms of ultrasonic atomization capabilities.
Investigation of the Effect of Low-Temperature Annealing and Impact Angle on the Erosion Performance of Nickel-Tungsten Carbide Cold Spray Coating Using Design of Experiments
Authors: Kazasidis M. , Verna E. , Yin S. , Lupoi R. 
Published: September 2022

Abstract
This study investigates the solid particle erosion performance of cold sprayed tungsten carbide-nickel coatings using alumina particles as erodent material. After coating fabrication, specimens were annealed in an electric furnace at a temperature of 600 °C for 1 hour. The coatings were examined in terms of microhardness and microstructure in the as-sprayed (AS) and annealed (AN) conditions. Subsequently, the erosion tests were carried out using a General Full Factorial Design with two control factors and two replicates for each experimental run. The effect of the annealing on the erosion behavior of the coating was investigated at the two levels (AS and AN conditions), along with the impact angle of the erodents at three levels (30°, 60°, 90°). Finally, two regression models that relate the impact angle to the mass loss were separately obtained for the two cold spray coatings.
A Decade of Development, Optimization and Scale Up of a Thin Barrier Layer for Metal-Supported Solid Oxide Fuel Cells
Authors: Leblanc L. , Hinckley R. , Alinger M. , Striker T. 
Published: September 2022

Abstract
A solid oxide fuel cell is an electrochemical conversion device that produces electricity directly from oxidizing a fuel. It involves ionic transport and electrochemical reactions where the electrolyte and electrode properties play a major role in performance, along with a range of complementary materials that need to ensure equally relevant functions across the cell. The lifetime of such functional materials is expected to reach many thousands of hours with minimal degradation. This article is centred around the process development, optimization and scale up of a thin plasma sprayed ceramic barrier layer to mitigate long-term performance degradation of metal-supported solid oxide fuel cells. The evolution from the proof of concept in a laboratory environment to the scale up toward large scale manufacturing production is discussed. The challenges associated with minimizing application time and lowering cost while maintaining high coating performance at high yield are discussed. Empirical observations such as microstructural analysis and in-flight particle monitoring are used to gain understanding of the plasma spray process and guide its development for high-volume production. Results show how this effort has led to the reduction of the coating deposition time by 94% to enable large-scale manufacturing at high yield.
Digital Process Chains for 3D Laser Cladding and LMD/DED Additive Manufacturing
Authors: Beccard R. , Bartling A. 
Published: September 2022

Abstract
Laser cladding or metal deposition (LMD/DED) is widely used for wear-resistant coatings, repair and additive manufacturing applications due to the excellent properties of the deposited material. However, processes on complex 3D surfaces are often a challenge because they require time-consuming programming. This is particularly the case when no CAD data is available for the parts on which metal coatings or structures have to be applied. As a solution, we describe a digital process chain that begins with a 3D scanning process within the laser cladding machine (either robotic or CNC type). Using special software, high-quality 3D models of the scanned parts are created. For coating applications, these models are visualized on a PC. The operator can define cladding areas with just a few clicks of the mouse. Based on predefined parameters, powerful software calculates all the required tool paths. An additional simulation step can be used to verify collision-free operation. Finally, robot or CNC programs are automatically generated that can be executed immediately. Similar software is used to create 3D parts directly from CAD files. Finally, by combining both approaches, 3D geometries can be printed directly onto existing 3D freeform parts using laser metal deposition/LMD, even if their shape is arbitrary and not well documented by CAD data.