bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanical Properties and Behaviour of BSAS/Mullite-Based Environmental Barrier Coatings Exposed to High Temperature in Water Vapour Environment
Authors: Cojocaru C.V. , Kruger S.E. , Lima R.S. , Moreau C. 
Published: September 2022

Abstract
Si-based ceramics (e.g., SiC and Si3N4) are known as promising high-temperature structural materials in various components where metals/alloys reached their ultimate performances (e.g., advanced gas turbine engines and structural components of future hypersonic vehicles). To alleviate the thickness recess that Si-based ceramics undergo in a high-temperature environmental attack (e.g., H2O vapour), appropriate refractory oxides are engineered as environmental barrier coatings (EBCs). Presently, the state-of-the art EBCs comprise multilayers of silicon (Si) bond coat, mullite (Al6Si2O13) intermediate layer and BaO-SrO-Al2O3-SiO2 (BSAS) top coat. Evaluating and understanding their mechanical properties, such as, the elastic modulus (E) and the strain-stress relationship is essential for their practical application and reliable employment. It was investigated via depth-sensing indentation the role of high-temperature treatment (1300°C), performed in H2O vapour environment (for time intervals up to 500 h), on the mechanical behaviour of air plasma sprayed Si/mullite/BSAS layers deposited on SiC substrates. Laser-ultrasonics was employed to evaluate the E values of as-sprayed coatings and to validate the indentation results. The fully crystalline, crack-free and near crack-free as-sprayed EBCs were engineered under controlled deposition conditions. The (i) absence of phase transformation and (ii) stability of the low elastic modulus values (e.g., ~60-70 GPa) retained by the BSAS top layers even after harsh environmental exposures provides a plausible explanation for the almost crack-free coatings observed. The measured mechanical properties of the EBCs and their microstructural behaviour during the high-temperature exposure are discussed and correlated.
Ti-Parts for Aviation Industry Produced by Cold Spraying
Authors: Binder K. , Gärtner F. , Klassen T. 
Published: September 2022

Abstract
Cold spraying has a high potential for building up thick coatings or structures, like for rapid prototyping or production of free-standing parts. This method is particularly interesting for high strength materials that are difficult to process or to shape, e.g. Titanium for special applications in aviation industries. In this contribution, the two major challenges are addressed: (I) optimizing mechanical properties by systematic variation of process parameters, and (ii) evaluating the influence of the spray angle with respect to complex geometries as requested by aviation industry. While in the past, high quality titanium coatings were only achieved using Helium as process gas, Nitrogen is used in this study to reduce costs. High deposition efficiencies of more than 95 % can be obtained and the coatings show very low porosities as well as high tensile strength of over 480 MPa. The influence of process conditions on the mechanical properties is discussed on the basis of coating microstructures, Micro Flat Tensile (MFT) and Tubular Coating Tensile tests (TCT-test).
High Temperature Mechanical Behaviour of UHTC Coatings for Thermal Protection of Re-Entry Vehicles
Authors: Pulci G. , Tului M. , Tirillò J. , Marra F. , Lionetti J. , Valente T. 
Published: September 2022

Abstract
In this work the high temperature mechanical properties of UHTC coatings deposited by plasma spraying have been investigated; particularly the stress-strain relationship of ZrB2 based thick films has been evaluated by means of 4-point bending tests up to 1500 °C in air. Results show that at each investigated temperature (500, 1000, 1500 °C) Modulus of Rupture (MOR) values are higher than the ones obtained at room temperature; moreover at 1500°C the UHTC coatings exhibit a marked plastic behaviour, maintaining a flexural strength 25 % higher compared to RT tested samples. The coefficient of linear thermal expansion (CTE) has been evaluated up to 1500 °C: obtained data are of primary importance for substrate selection, interface design and to analyze the thermo-mechanical behaviour of coating-substrate coupled system. Finally SEM-EDS analyses have been carried out on as sprayed and tested materials in order to understand the mechanisms of reinforcement activated by high temperature exposure and to identify the microstructural modifications induced by the combination of mechanical loads and temperature in an oxidizing environment.
Influence of the Surface State on the Adherence of the Coating: Case of an Alumina Coating Plasma Sprayed on SiC Composites
Authors: Costil S. , Lukat S. , Verdy C. , Coddet C. 
Published: September 2022

Abstract
The quality of thermally sprayed coatings depends on a lot of parameters (spraying power, feedstock injection, morphology of the parts, kinetics and environment). But among them, adherence between the coating and the substrate appears as the fundamental point. To favor a good interaction and also a good adherence between the coating and the substrate, it is often necessary to clean and prepare the substrate surface. Conventionally, solvents and sand-blasting are applied to remove the contaminants and increase the surface roughness for a mechanical anchorage. But according to the substrate nature (ceramic) or the substrate morphology, it can be prejudicial to apply a mechanical treatment due to a peeling of the surface or a decrease of the global properties. By this way some other treatments have to be investigated in order to obtain an appropriate preparation. From all of them (water jet, ice blasting, heating treatment, etc.), laser ablation can be an interesting technology to prepare the substrate surface. The aim of this work was to study the modifications induced by 10 ns single or cumulative pulses of a Q-switched Nd:YAG near-infrared laser and its influence on the interface adhesion. The case of an alumina coating sprayed on a Ceramic Matrix Composite (CMC) has been studied. In these conditions, the laser treatment seems favorable from the adherence point of view according to the mechanical effect (induced by a cone-like structure) and the chemical effect
Comparison of Two Structure Scales of Plasma Sprayed Al2O3-TiO2 Coatings on Mechanical and Tribological Properties
Authors: Vargas F. , Ageorges H. , Xin W. , Fauchais P. , Lopez M. 
Published: September 2022

Abstract
Al2O3-13 % wt TiO2 thermal sprayed coatings exhibit good wear resistance under tribological conditions, thanks to their high toughness. Alumina/titania coatings with two different structures, and similar titania content, have been elaborated by atmospheric plasma spraying (APS). The aim was to compare the effect of the structure on hardness and wear resistance. As feedstocks were used Al2O3-13 wt % TiO2 powders with two different structures: micrometer sized ones, with two size distributions (5 – 30 μm and 15 – 45 μm), and agglomerated nano-meter sized particles (grain diameters between 200 to 500 nm) with a size distribution between 10 and 45 μm. Coatings were sprayed onto low carbon steel (XC38) substrates with several spray parameters, the plasma forming gas used being mixtures of Ar and H2 (45/15 and 53/17 SLM, respectively). Results show that, with the tribological conditions used in this study, the wear resistance of coatings principally depends of their hardness and not very much on the starting powder morphologies.
TBC Dry Ice Stripping
Authors: Giolli C. , Allegrini B. , Duda T. , Engl L. , Giorgetti A. , Groppetti A. , Lanzi L. , Pini S. , Spagnoli M. , Scrivani A. 
Published: September 2022

Abstract
Thermal barrier coatings have got considerable importance for the improvement of gas turbine efficiency. These materials are applied on the surface of gas turbine blades and vanes and are based on a layer of low-oxidation material (mainly MCrAlY alloys, where M stay of Co, Ni or a combination of both) and a ceramic top layer that acts as proper thermal barrier (normally Yttria Partially Stabilized Zirconia). Coating removal is an important aspect in the production of these blades and vanes. “Decoating” or “stripping” is needed during the production of new components as well as for the reconditioning of existing ones. The present paper is dedicated to a new removal method of the ceramic Zirconia layer, based on dry ice blasting. This method will not impact on the roughness and morphology of the bond coat surface, making it suitable for re-coating with TBC, without any further operation before TBC recoating. This possibility has an important impact on the stripping costs and time, avoiding all the operations related to the bond coat. The paper presents the process tests to get the process set up and the characterization of the surfaces comparing the stripped ones with the “original ones” coated by LPPS on new components, ready to be TBC coated. Optical and SEM microscopy, 3D profilometry have been used for characterization. Finally a Thermal Cycling Fatigue test has been carried out in order to validate the procedure of stripping and re-coating.
Influence of Pores and Cracks Morphology on Mechanical Behavior of Thermally Sprayed Ceramics
Authors: Mušálek R , Matìjíèek J. , Pejchal V. , Mari E. , Valarezo A. , Sampath S. 
Published: September 2022

Abstract
Pores and cracks have significant influence on the structural rigidity and mechanical behavior of the thermally sprayed materials. For some applications dense coatings are needed, while for others (e.g. thermal barriers) some level of porosity is desirable. Recent development in thermal spraying focuses on the tailored design of pores and cracks for specific applications. In this project, ceramic coatings with different level and morphology of pores and cracks were plasma and HVOF sprayed on titanium alloy substrates. Coating microstructures were observed using scanning electron microscopy. Mechanical behavior of the prepared coatings was evaluated using four-point bending test in terms of changing coating stiffness with increasing mechanical load both in compression and tension. Significant level of coating non-linearity and hysteresis were observed. Tests carried out for coatings with the same chemical composition but different microstructure proved strong dependency of coatings mechanical properties on pores and cracks morphology. Microstructure features relevant for the applied loading are discussed.
Design of Experiment Analysis of the Sulzer Metco DJ High Velocity Oxy-Fuel Coating of Hydroxyapatite for Orthopaedic Applications
Authors: Hasan S. , Stokes J. 
Published: September 2022

Abstract
HVOF has the potential to produce Hydroxyapatite HA (Bio-ceramic) coatings based on its experience with other sprayed ceramic materials. This technique should offer mechanical and biological results comparable to other thermal spraying processes such as plasma spray currently FDA approved for HA deposition. Deposition of HA via HVOF is a new venture especially using the Sulzer Metco Diamond Jet (DJ) process, hence the aim of this paper. In this research, a Design of Experiment (DOE) model as developed to optimize the HVOF process for the deposition of HA. Five parameters (factors) were researched over two levels namely: oxygen flow rate, propylene flow rate, air flow rate, spray distance and powder flow rate. Coating crystallinity and purity were measured as the responses to the factors used. The research showed that: propylene, air flow rate, spray distance and powder feed rate had the largest effect on the responses and the study aimed to find the desired optimised settings. This research found crystallinity and purity values of 93.8% and 99.8% respectively for a set of HVOF parameters which were improved findings compared to the crystallinity and purity of 87.6 % and 99.4 % respectively found using the FDA approved Plasma thermal spray process. Hence a new technique for HA deposition now exists using the DJ HVOF facility. Future research aims to evaluate the biological response to these coatings through in vitro tests.
Mechanical Behaviour of Air-Plasma Sprayed Functionally Graded YSZ-Mullite Environmental Barrier Coatings: A Study Via Instrumented Indentation
Authors: Cojocaru C. V. , Wang Y. , Lima R. S. , Moreau C. , Mesquita-Guimarães J. , Garcia E. , Miranzo P. , Osendi M. I. 
Published: September 2022

Abstract
Mullite (Al6Si2O13) is the basis of efficient environmental barrier coatings (EBCs) for protecting Si-based ceramic matrix composites (CMCs) selected to replace specific hot-section metallic components in advanced gas turbines. Furthermore, YSZ-mullite multilayer architectures with compositional grading between the bond coat and YSZ top coat were envisioned as solutions to ease their coefficient of thermal expansion (CTE) mismatch induced stress. Consequently, a proper understanding of the mechanical properties such as the elastic modulus, hardness or plastic/elastic recovery work serve for an efficient design of such refractory oxide multilayers. In this work, three different mullite powder morphologies (fused and crushed, spray-dried and freeze-granulated) were employed. Using depth-sensing indentation with loads in the range 100 – 500 mN, the role of the microstructure and morphology of the powder feedstock on the mechanical behaviour of air plasma sprayed mullite bond coats deposited on SiC Hexoloy substrates was investigated. Fully crystalline as-sprayed mullite coatings were engineered under controlled deposition conditions. Mechanical properties were measured for the as-sprayed coatings as well as for coatings heat-treated at 1300°C, in water vapour environment, for periods up to 500 h. Both E and H values of the coatings are found to be highly dependent on the morphology of the starting powders.
Microstructure and Electrochemical Behavior of Fe-Based Amorphous Metallic Coatings Fabricated by Atmospheric Plasma Spraying
Authors: Zhou Z. , Wang L. , He D. , Wang F. , Liu Y. 
Published: September 2022

Abstract
A Fe48Cr15Mo14C15B6Y2 alloy with high glass forming ability (GFA) was selected to prepare amorphous metallic coatings by atmospheric plasma spraying (APS) process. The as-deposited coatings present a dense layered structure and low porosity. Microstructural studies show that some nanocrystals and a fraction of yttrium oxides formed during spraying process, which induced the amorphous fraction of the coatings decreasing to 69% compared with fully amorphous alloy ribbons of the same component. High thermal stability employs the amorphous coatings to work below 910K temperature without crystallization. Corrosion behavior of the amorphous coating was investigated by electrochemical measurement. The results show that the coatings exhibit extremely wide passive region and low passive current density in 3.5% NaCl and 1mol/L HCl solutions, which illustrate their superior ability to resist localized corrosion. Moreover, the corrosion behavior of the amorphous coatings in 1mol/L H2SO4 solution is similar to their performance in chlorine ions contained conditions, which manifests their flexible and extensive ability to withstand aggressive environments.
Analysis of Fe-base Materials and Evaluation of their Suitability for Wear Protection Coatings
Authors: Pelz A. 
Published: September 2022

Abstract
Recently much research work has been undertaken worldwide to develop iron base materials which can be used for thermal spraying of anti-wear coatings. Besides economical ideas reasons exist like health- and environmental aspects for the usability of iron base materials instead of Ni- or Co containing carbide coatings. Until now, however, iron base materials showed a worse life time under abrasive wear compared with conventional carbide coatings like WC/ CO or NiCr-CrC. This article presents the research work on new iron base materials for wear protection purposes. Thereby, the focus is set on high carbon containing iron-chromium base alloys which solidify under the formation of primary carbides. The material development included the study of different additional alloying elements. The relation of different chemical compositions and their typical microstructure to the wear behaviour is presented in this paper, too. To follow an integral way for the evaluation of the wear behaviour both powders and cored-wires could be produced. Therefore the wear tests considered coatings produced via HVOF, PTA and arc-spraying.
Effects of WC Particle Size on Deposition of Cold Spray WC-Co Coatings
Authors: Berndt C. C. , Ang S. M. , Cheang P. , Wang J. 
Published: September 2022

Abstract
Cold spray is a material deposition process that uses a high pressure, high velocity gas jet for the deformation and bonding of particles. However, deposition of brittle or hard materials such as ceramics has not been successful: unless they are co-deposited with a ductile matrix material. This paper examines the WC particle size and its influence on the deposition of Co-based cermets. Micro- and nano-structured powders with similar Co content were employed. Varying the WC particle size influenced significantly the deposition efficiency of the coating process. Micrometer-structured WC-Co feedstocks did not permit coating build up when processed under comparable or elevated thermal spray parameters used for the nanostructured WC-Co feedstocks. In addition, micrometer-structured WC-Co coatings exhibited a conjoint erosion and deposition effect on the surface. Fine WC particles (&lt;1 μm) were observed near to the substrate interface and larger WC particles (1-2 μm) in the vicinity of the coating surface. These observations indicate the existence of a critical WC particle size for deposition by the cold spray method and that the size criteria arises due to the formation and cohesion mechanisms within the coating layer.
Modeling of Particle Consolidation by Cold Spray
Authors: Kocimski J. , Maev R.Gr. , Leshchynsky V. , Kocimski J. , Ambroziak A. 
Published: September 2022

Abstract
To fully understand particle interactions with both substrate and neighboring particles, Finite Element Analysis (FEM) of particle agglomeration impact onto substrate was developed. To investigate particle/particle bonding mechanism, two dimensional models for various initial densities of deposited stainless steel particles has been built. In the model the stainless steel powder was deposited onto copper substrate. The results obtained from simulations show the influence of particle agglomeration density on stress and strain state. Both plastic strains, stresses and dynamics of the process has been investigated. The model was verified and compared with metallographic structures of real coatings.
Effect of Powder Preheating Temperature on the Properties of Cu-Based Amorphous Coating Layer by Cold Spray Deposition
Authors: Cho J. , Park D. , Kim J. , Lee J. , Lee K. 
Published: September 2022

Abstract
Cu54Zr22Ti18Ni6 amorphous powders were deposited onto aluminum substrates by cold spray process with different powder preheating temperature (below Tg : 623K, near Tg : 703K, and Tx : 773K). The microstructure and macroscopic properties of coating layers were investigated using OM, XRD, DSC and hardness, SUGA test, potentio-dynamic corrosion test. XRD results showed that cold sprayed Cu based amorphous coating layers of 300~350 μm thickness could be well manufactured regardless of powder preheating temperature. Porosity measurements revealed that the coating layers of 623K and 773K preheating temperature conditions had lower porosity contents (0.88%, 0.93%) than that of 623K preheating conditions (4.87%). Hardness was measured as 374.8HV (623K), 436.3HV (703K) and 455.4HV (773K) for the coating layers, respectively. Results from the wear resistance examination via SUGA test and those from the hardness testing showed the same trends. Examination of corrosion resistance of the amorphous coating layer showed that the critical anodic current density (ic) of the coating layer, for which powder preheating was provided at 623K and then cold spray deposition, was 5.6X10-3A/cm2. The ic values of the 703K and 773K coating layers were 4.8X10-4 and 1.2X10-3A/cm2, respectively. Both temperature conditions were found to offer superior corrosion characteristics to those of the 623K-prehaeted and coated specimen. This was assumed to be attributed to the relatively lower level of porosity.
Location of the Powder Injection as Independent Parameter to Control Particle Velocity and Temperature in Cold Spray
Authors: Sova A. , Kosarev V. , Klinkov S. , Smurov I. 
Published: September 2022

Abstract
Particle-at-impact parameters in Cold Spray are governed mostly by gas flow parameters. However, the location of the powder injection can be used as independent factor to modify particle-in-flight parameters. Calculations and experiments confirm strong influence of the location of the powder injection on dynamics of particle acceleration and heating. Application of this effect for cold spraying of multicomponent coatings is a new and promising approach. The general scheme of spraying of two-component mixture composed of hard-sprayable and easy-sprayable components proposed as follows: The hard-sprayable component is injected into the subsonic part of the nozzle at a gas stagnation temperature favorable for this material to start the coating formation alone. The zone of injection of the easy-sprayable component is determined in such a way that the particles of this material have, at the nozzle outlet, values of temperature and velocity sufficient for the coating formation at the selected gas stagnation temperature. New design of spraying nozzle for the above purposes is proposed and discussed.
Computer-Aided Cooling Curve Used to Predict the Solidification Behavior of Cast Iron
Authors: Shaha S. K. , Haque M. M. 
Published: September 2022

Abstract
During solidification, the cooling behaviour of materials depends on the heat flow through the mould and the alloy composition. Even though the alloy composition is same; the cooling rate can change the properties of the materials. In the present study, an attempt has been taken to predict the cooling behaviour of gray cast iron into a resin bonded sand mould at various thicknesses using JL FEM analyser software. Using K-type thermocouple, the temperature was measured after every 20 sec. Both, the computer simulated and experimentally investigated cooling curves show the similar nature or pattern of the curves. The microstructure also confirms that the cooling rate changes the structure of the cast iron from gray to white.
Characteristics of Cu Film-Like Coating Deposited Using VLPPS
Authors: Zhang N. , Sun F. , Zhu L. , Verdy C. , Planche M. P. , Liao H. , Coddet C. 
Published: September 2022

Abstract
Cu coatings were obtained by the VLPPS (Very Low Pressure Plasma Spray) process using a torch F4-VB. The tank pressure was varied from 1 mbar to 5 mbar: these specific conditions can allow obtaining a higher vapor condensation fraction in the coating. Different sizes of powders are used to compare the vaporization level. The other possible influencing factors for obtaining compact film-like coating are also considered such as the distance between the torch and substrate, the orientation of the vapors and also the substrate temperatures. Microstructures of coatings are analyzed and combined with the results of plasma diagnostics. Jobin-Yvon spectrometer (type TRIAX190, UK) and Plasus Specline Spectroscopy software are both used for detecting and analyzing plasma spectrum data. The value of plasma electronic excited temperature Te was calculated through choosing Hα and Hβ two atom spectra. The results showed that the plasma belongs to cold plasma in the local thermodynamic equilibrium situation in VLPPS.