bluuebunny/crossref_metadata_2025_split huggingface dataset:
Performance of Multilayered Mullite-Based EBCs in Simulated Working Conditions
Authors: Garcia E. , Mesquita-Guimarães J. , Miranzo P. , Osendi M. I. , Cojocaru C. V. , Moreau C. , Lima R. S. 
Published: November 2022

Abstract
Compositionally graded mullite/ZrO2 coatings, have been tested as environmental barrier coatings (EBCs) for protection against water vapor corrosion of Si-based ceramic components intended for application in turbine engines. Four and five layered systems were engineered by plasma spraying over SiC substrates consisting of a Si bond coat layer, 2 or 3 mullite/ZrO2 composite graded layers as middle layers and a nanostructured YSZ topcoat. These coatings were heat treated at 1300 °C in both stationary and thermal cycling conditions in a controlled water vapor environment. The effect of these ageing conditions on the coatings was comparatively investigated. Crystallization of the composite coatings and sintering of the YSZ topcoat was perceived. A reduction of SiO2 content was detected in the composite layers before aging. The porosity of the coating did not change appreciably with the ageing tests and only the evolution of the pre-existing cracks and the growing of a thermally grown oxide layer can be highlighted as the major effect of the ageing tests.
New Cermet Powders for HVOF Spraying with Improved Corrosion and Oxidation Resistance for Offshore, Mining and Power Generation Applications
Authors: Zimmermann S. , Gries B. , Brüning B. 
Published: November 2022

Abstract
The present study describes the development of agglomerated and sintered WC and Cr3C2 based cermet powders with complex and highly corrosion resistant Fe and Ni matrix alloys. In addition a Fe-Cr-C with a Ni matrix was tested as a potential low cost alternative to standard Cr3C2-NiCr powders. The powders were sprayed by HVOF using liquid and gaseous fuel. Microstructure and phase composition of the coatings were analyzed by microscopy and X-ray diffraction. The technical properties of the coatings were examined by hardness measurements, abrasive wear and cavitation tests as well as corrosion tests. The results were compared with state-of-the-art coatings of WC-Co-Cr 86/10/4 and Cr3C2-NiCr 75/25.
Novel Titania (TiOx) Feed-Stock Powder for Significant Improvements in Process Economics and Enhanced Coating Properties
Authors: Sharma A. , Nestler M. C. , Colmenares-Angulo J. , Medrano J. , Rauch J. , Weder M. , Wilson S. 
Published: November 2022

Abstract
Traditional fused and crushed (F&C) titania feedstock powders have relatively poor flow and are limited in the feed-rates that can be achieved before deposition efficiencies (DEs) start to decline. In addition, the coatings made with F&C powders generally have high stiffness and limited fracture toughness. Such coatings bear the risk of cracking/delaminating particularly in the case of thick coatings. To address these issues, a new agglomerated and sintered (A&S) titania feedstock powder has been developed and compared in side-by-side spray tests to the traditional F&C titania powder of comparable particle size. The spray behavior, achievable feed-rates and DEs, as well as the resulting coating characteristics were evaluated from the view point of their application as thick, electrically conductive coatings. The new A&S powder yields up to approximately 200% improvement in DE while producing coatings with more suitable microstructure, lower electrical resistivity and higher thickness. Furthermore, for a given set of process parameters, the DEs obtained with this new powder show little sensitivity to the powder feed-rates, thus allowing spraying at higher feed-rates without compromising coating DEs. This feature of the powder has significant commercial advantages for thick coatings when combined with high throughput guns such as TriplexPro-200. Preliminary results of particle diagnostics towards understanding of the fundamental principles behind these improvements are also discussed.
Cold Spraying of Ceramic Coatings – A Feasibility Study
Authors: Ravanbakhsh S. , Assadi H. , Nekoomanesh H. , Hassanzadeh A. , Taheri-Nassaj E. 
Published: November 2022

Abstract
In this study feasibility of cold spraying to produce ceramic coatings is investigated. Ceramic coatings have high potential for various industrial applications. A main problem with these coatings is undesirable phase transformations caused by high temperatures, as in conventional thermal spraying methods. There have so far been few examples of successful cold spraying of ceramics. This work is to examine the problem further by synthesizing specially tailored porous powders, using the sol-gel method. The powders were sprayed on different substrates using a cold spray system. The deposits were characterized by optical and scanning electron microscopy. Based on the results, a discussion of the optimal powder characteristics for cold spraying of ceramics is presented.
Atmospheric Plasma Spraying of Electrodes for Conversion of Electricity to Hydrogen by High Temperature Alkaline Electrolysis of Water
Authors: Nielsen P. T. , Mathiesen T. , Kristensen J. K. , Hilbert L. , Yde L. 
Published: November 2022

Abstract
Energy obtained by wind turbines can be foreseen to constitute a significant part of the future energy sources. A major challenge is however the large variation over time in wind energy production. Energy conversion from electricity to storable energy is therefore a key technology to master, and it is therefore important to develop compact, reliable, cheap and energy efficient equipment for this. An obvious solution is production of hydrogen based on water alkaline electrolysis. In the work presented the atmospheric plasma spraying (APS) of Raney nickel (50/50 Ni/Al) was used to develop electrodes with a large specific surface area as well as a considerable energy efficiency in high temperature water alkaline electrolysis. The coating process was analyzed using a plume analyzer as the primary tool and the coating properties were analyzed by a combination of bonding strength measurement, optical (OM) and scanning electron microscopy (SEM) as well as testing of the activated electrodes in a laboratory electrolysis cell. The results of the spraying process analysis are reported together with the electrochemical properties of the activated electrodes, and with regard to energy efficiency very positive results are obtained for the measured overvoltage.
Effect of Directional Re-Solidification on Thermal Plasma Spray Silicon Depositions
Authors: Jackson D. D. , Sereda M. , Gansert R. 
Published: November 2022

Abstract
Thermal plasma spray of silicon has large potential for economic impact in the semiconductor and solar power industries. By post processing a thermally sprayed silicon deposition using directional re-solidification, impurities in the substrate can be controlled. We used a Thermach gun and powder feeder (SG100 and AT-1200, respectively, Appleton, WI), to deposit silicon onto steel samples. These samples were optically heat treated up to their melting point in order to increase crystal grain sizes. The depth and microstructure of the melted region was analyzed through imaging of the cross-sectioned samples. Directional re-solidification also had an effect on the impurity concentration along the depth sample. Control of impurities is demonstrated through this heat treatment and analyzed using SIMS and Laser Ablated ICP-MS. Understanding and controlling the impurity concentration has important implications in producing coatings in the solar industry as well as wafer processing equipment in the semiconductor industry.
Solar Selective Coatings for Concentrating Solar Power Central Receivers
Authors: Hall A. , Every K. V. , Knight M. , Mccloskey J. , Urrea D. , Ambrosini A. , Lambert T. , Siegel N. , Mahoney A. , Ho C. 
Published: November 2022

Abstract
Concentrating solar power (CSP) systems represent a zero emission method for conversion of sunlight to electricity. CSP systems use an array of mirrors to concentrate sunlight on the surface of a heat exchanger and heat a working fluid. These heat exchanger surfaces must have high absorptivity and low emissivity in the solar spectrum. In addition, they must be capable of extended operation at temperatures in excess of 600°C. Initial development of solar selective coatings using the air plasma spray process will be discussed. Eight different coating materials were deposited onto 304L stainless steel substrates. Solar absorptance and emittance were measured from each coating in three conditions: as-deposited, after heat treatment at 600°C for six hours, and after polishing to a 1 µm finish. A figure of merit based upon solar power tower (SPT) operation was calculated from these data and compared to the industry standard solar selective coating for SPT receivers, Pyromark Series 2500 high temperature paint. This comparison shows that Ni-5Al, 80WC-20Co, and CeO plasma-sprayed coatings all have potential as solar selective surfaces for SPT receivers.
Cold Gas Spraying of Ceramics Using the Example of Titanium Dioxide
Authors: Gutzmann H. , Freese S. , Gärtner F. , Klassen T. 
Published: November 2022

Abstract
Functional titanium dioxide coatings have a high potential for photocatalytic applications. However, the high process temperatures of conventional thermal spray methods lead to undesirable phase transformations. Cold gas spraying seems to be beneficial, since for ceramic coatings no phase transformations have been observed so far. In this study, bonding of cold-sprayed ceramic particles on metal substrates is elucidated by investigating single impacts obtained from wipe tests. Different feedstock powders were used, consisting of agglomerated titanium dioxide nanoparticles. The single particle impacts were investigated by scanning electron microscopy and confocal microscopy. The results demonstrate that bonding of particles is influenced by the substrate material, substrate temperature, powder properties and spray conditions. In addition, powder characteristics seem to be of particular importance. The results allow for conclusions regarding favorable conditions for cold spraying of ceramics.
Influence of the Suspension Characteristics and Spraying Parameters on the Properties of Dense Suspension-HVOF Sprayed Al2O3 Coatings
Authors: Toma F.-L. , Langner S. , Barbosa M. M. , Berger L.-M. , Rödel C. , Potthoff A. 
Published: November 2022

Abstract
In this work suspension-HVOF spraying (S-HVOF) was used to prepare dense and mechanical stable Al2O3 sprayed coatings with high contents of α-Al2O3 phase. Aqueous suspensions with various contents of powder (from 25 wt.% up to 50 wt.%) have been developed starting from two commercial α-Al2O3 powders, characterized by different purity and particle sizes. The suspensions have been internally injected in a modified combustion chamber of a HVOF TopGun-torch. Coating microstructures, phase compositions and mechanical properties resulting from the interaction between suspension characteristics and spray parameters are presented. Use of suspensions with high solid contents allowed the production of thick, dense and mechanically stable coatings. The α-Al2O3 was the main phase in the coatings produced through the injection of suspensions containing powders with very high purity.
Important and More In-Demand than Ever: Training and Qualification of Thermal Spray Personnel
Authors: Huber R. , Ohliger-Volmer A. 
Published: November 2022

Abstract
Thermal spraying is a constantly expanding technology within the surface technology sector, established long time in a wide range of hi-tech applications. Whether in jet engines, in power plants or the printing industry, endless coating requirements can be fulfilled with thermal spraying. However in order to master the “special process” – a term used in international standards and rules – calibrated and monitored systems and parameters are needed. Also, experienced, trained and certified personnel plays an important role to rule such a special process, whose results can only be tested by non-destructive methods to a certain restricted extent. Training and examination of spray personnel is aligned with the respective European training and qualification guidelines of the EWF (European Federation of Welding, Joining and Cutting). Passing the examination, especially for the thermal sprayers confirms their technical proficiency and skills. Additionally, it clearly influences the worker´s labour input and his quality awareness in the workplace. Compliance with standards like ISO 9001 or GTS-QM-Guidelines, means for companies to have their staff trained, qualified and further educated. Experiences have shown that - contrary to expectations - the complete EWF training is in high demand. Sectors such as aerospace, railway and power plant engineering are also increasingly demanding the qualifications for ETS – European Thermal Sprayer and ETSS – European Thermal Spraying Specialist.
Modelling Ceramic Droplet Impingement
Authors: Tabbara H. , Kamnis S. , Gu S. 
Published: November 2022

Abstract
Ceramic powders such as zirconia and titania are especially useful in their application as thermal barrier coatings, but are also useful in the production of more advanced coatings such as the dye-sensitized solar cell and functionally gradient prosthetic coatings. Due to their low thermal conductivity large temperature gradients through the powder particles are experienced during plasma spray deposition. As a result the particles often impinge at the substrate in a semi-molten form, which in turn substantially affects the final performance characteristics of the coating. This paper firstly summarizes some simulations and key results for completely solid and completely liquid particles. The modelling of semi-molten droplet impingement is then outlined, which is applicable to ceramic powders. The study examines the semi-solid impingement process during impact, spreading and solidification, and contributes to the growing insight being provided by numerical simulations on the topic of particle impingement in thermal spraying.
Detonation Spraying of TiO2-Ag Powders Under a Controllable Atmosphere
Authors: Dudina D. V. , Zlobin S. B. , Yu V. , Ulianitsky N. , Bulina V. , Bychkov A. L. , Lomovsky O. I. 
Published: November 2022

Abstract
In the present work, TiO2(rutile)-2.5vol.%Ag composite powders produced by mechanical milling were detonation sprayed under different atmospheres using acytelene as a fuel. The atmosphere of spraying was set to be reducing or oxidizing by changing the O2/C2H2 mole ratio. Reduction of TiO2 to Ti3O5 occurred in the coatings deposited under a reducing atmosphere (O2/C2H2 =1.05) when particles were heated to reach a molten or a semi-molten state. In the coatings sprayed using a stoichiometric O2/C2H2 =2.5 mixture, the major phase was rutile. The composition of the atmosphere does not only determine the chemical environment for the sprayed powders, but also influences the temperature conditions. Increasing oxygen content in the explosive mixture led to much higher temperatures of the sprayed particles as was calculated using a previously elaborated model. When titanium dioxide did not reach melting, the coatings were porous with a spongy surface. Coatings formed by fully or partially molten particles possessed a denser structure. Silver particles experienced melting during spraying but remained uniformly distributed in the coatings. This study demonstrated that careful selection of the composition of the spraying atmosphere offers potential of controlling the phase composition and microstructure of the detonation sprayed coatings.
Characterization of Novel Bioactive Hydroxyapatite-TiO2 Coatings Obtained by High Velocity Oxy-Fuel
Authors: Melero H. , Fernández J. , Dosta S. , Guilemany J. M. 
Published: November 2022

Abstract
Hydroxyapatite (HAp: Ca10(PO4)6OH2) is a biocompatible and bioactive ceramic material widely used as a coating on metal surfaces (dental implants, hip replacements ...), but the low adhesion between HAp and the substrate due to the differences in thermal expansion coefficients of both, and the degradation of HAp, is being improved through the addition of TiO2 to reach a good combination of mechanical properties. Therefore, the objective of this project is to produce 80%HAp-20%TiO2 (by weight) coatings on Ti6Al4V by High-Velocity Oxy Fuel (HVOF). The microstructure study has been carried out using scanning electron microscopy, and the characterization of the present phases, hydroxyapatite and rutile mainly, using X-ray diffraction and Raman spectroscopy (the last one to find out which are the minority phases, such as anatase and tricalcium phosphates). Also Rietveld method has been used to quantify the amount of amorphous phase, lower than in the case of plasma-sprayed coatings. The coatings adhesion has been measured by tensile tests according to ASTM C633-01(2008), finding an improvement over the adhesion of plasma sprayed coatings, and also of hydroxyapatite coatings; also their bioactivity has been evaluated through its immersion in simulated body fluid (SBF), and through in vitro tests to study osteoblast behaviour on the coatings surfaces, with positive results. To conclude, a discussion about the results is made to analyze the industrial viability of these kinds of coatings.
Life Cycle Assessment of Surface Preparation Processes Implemented before Thermal Spray
Authors: Serres N. , Costil S. , Lamraoui A. , Langlade C. , Coddet C. 
Published: November 2022

Abstract
The aim of this paper is to propose a LCA comparison of different surface preparation processes (degreasing + sandblasting, laser ablation and laser texturing) which tend to be used before thermal spray. The SimaPro software was used and the needs of materials, the energy and the corresponding emissions of each process, were converted to impact scores on human health, ecosystems, and resource conservation (fossil and mineral resources) by mean of the Eco-Indicator-99 method. Laser pretreatments processes present a very good environmental behaviour in comparison with degreasing + sandblasting.
Review on the Art of Anilox-Manufacturing – from the Coated Cylinder up to the Gravure
Authors: Döring J.-E. , de Schoulepnikoff L. 
Published: November 2022

Abstract
Anilox rolls are used as metering rolls in the flexographic printing process, delivering a precise quantity of ink to the plate roll (which contains the image to be printed). Anilox rolls are high precision parts with respect to their dimensional tolerances as well as to the engraved structures. The latter can nowadays be either very coarse in conjunction with a high volume of ink to be transferred or rather fine showing cell diameter of 20 µm, cell walls below 3 µm in thickness and cell depth of only 6 µm and below. Moreover, the market needs for high quality printing will lead more and more to the outer limits of these ranges, which can be matched only by tailoring the coating properties, as well as the interaction of the laser radiation with the sprayed surface. Besides the needs for extreme screen counts in conjunction with requirements of certain volumes of liquid to be transferred, new types of surfaces are needed to meet these requirements and providing a wear resistant coating and concurrent an easy to clean surface. Therefore this paper will give a review of the interaction of the laser with a thermally sprayed surface focussing on the main laser parameters, different coating materials, the application of sealants as well as the type of engravings with respect to the achievable screen counts and transferrable ink volumes.
Novel Thermal Barrier Coatings Produced by Axial Suspension Plasma Spray
Authors: Tang Z. , Kim H. , Yaroslavski I. , Masindo G. , Celler Z. , Ellsworth D. 
Published: November 2022

Abstract
Ceramic Thermal Barrier Coatings (TBCs) on superalloy components are being used successfully in land-based gas turbine and aircraft engines. These coatings are generally made by either air plasma spraying (APS) or electron beam physical vapour deposition (EB-PVD). In general, EB-PVD TBCs have superior durability due to the columnar structure, but they are very expensive compared to APS TBCs. EB-PVD TBCs are used primarily in the most severe applications such as turbine blades and vanes in aircraft engines. This paper presents an economical process to make durable TBCs, called Axial Suspension Plasma Spray (ASPS). This technology combines Mettech’s axial injection plasma process and automatic suspension feed system. The resulting TBCs exhibit columnar structures with vertical cracks, similar to EB-PVD coatings. Such structures allow the TBC to compensate for thermal expansion differences between it and the base material. The ASPS process presents an economical alternative to EB-PVD to produce durable columnar TBCs.
Yttrium Silicate Coatings by Sol Precursor Plasma Spraying for Environmental Barrier Applications
Authors: Quet A. , Bianchi L. , Darthout E. , Gitzhofer F. , Leluan J. L. , Rebillat F. 
Published: November 2022

Abstract
Yttrium silicates are among the candidates for protection of silicon-based ceramics in high temperature and moist environments due to chemical and mechanical compatibility with substrate, low volatility and moisture resistance. Here we reported on the development of yttrium silicate coatings by sol precursor plasma spraying. The use of a sol feedstock allowed easy composition flexibility. The microstructure and the structure of as-sprayed and heat-treated coatings were investigated. Finer microstructure was obtained compared to micrometric powder plasma spraying traditionally used to produce environmental barrier coatings (EBC). XRD analyses on as-sprayed coatings revealed amorphous or crystalline layers depending on plasma parameters. In EBC application, a volume change from crystallization or phase transformation was envisaged to be damaging due to induced stresses and fully crystalline phases are a key durability requirement for EBC from conventional plasma spraying. Yttrium silicates are characterized by an important polymorphism and the ability to form amorphous coatings. Therefore, special attention was so paid to the amorphous degree of the coatings.
Wear Behaviour of HVOF-Sprayed Nanostructured WC-CoCr Coatings
Authors: Bergonzini E. , Bolelli G. , Bonferroni B. , Lusvarghi L. , Varis T. , Kanerva U. , Suhonen T. , Oksanen J. , Söderberg O. , Hannula S.-.P 
Published: November 2022

Abstract
HVOF-sprayed WC–10wt%Co–4wt.%Cr coatings were obtained using experimental feedstock powders (manufactured by spray-drying + sintering), containing nanometric carbide particles. Three reference coatings were also deposited using commercially-available powders containing sub-micrometric carbide particles. The coatings obtained from nanostructured powders, although affected by decarburisation phenomena, contained very fine carbide particles (~200 nm size). Those obtained from commercially-available powders simultaneously exhibited sub-micrometric (~400 nm size) and micrometric carbide particles, and were much less decarburised. Sliding wear tests performed at room temperature against sintered Al2O3 balls showed the occurrence of brittle fracture wear (detachment of near-surface material by local brittle cracking) on the nanostructured coatings, which were embrittled by decarburisation. The reference coatings, by contrast, exhibited either ductile wear behaviour (plastic deformation, pull-out of single carbide particles) or a mix of both ductile and brittle wear mechanisms. When the decarburisation of the nanostructured coatings was not too extensive, their wear loss was comparable to that of the reference ones. At 500 °C, the wear behaviour of all coatings was dominated by abrasive grooving, on account of thermal softening. The most decarburised nanostructured coatings, however, still experienced brittle cracking as well.