bluuebunny/crossref_metadata_2025 huggingface dataset:
Kalp yetersizliği hastalarında depresyon ve anksiyete
Authors: TOK Ozge	ozden , YILMAZ Yasin , SAKALLI KANİ Ayşe , İNCE GULİYEV Ezgi , KILICKIRAN AVCI Burcak , YİĞİT Zerrin , BALCIOĞLU İbrahim , ÖNGEN Zeki
Published: June 2022

Amaç: Kalp yetersizliği, kalp fonksiyonlarının kronik, ilerleyici bozukluğu ile karakterize, yüksek mortalite ve morbiditesi olan bir durumdur. Depresyon ve anksiyete gibi psikolojik semptomlar kalp yetersizliği hastalarında sık görülmekle birlikte, mortalite, fonksiyon bozukluğu ve tedaviye uyum zorluğu gibi sorunlarla da ilişkilidir. Bu çalışmada, kalp yetersizliği hastalarında depresyon ve anksiyete semptomlarını araştırmayı planladık.Gereç ve yöntem: Bu kesitsel gözlem çalışmasında Hastane Anksiyete ve Depresyon Ölçeği (HAD) kullanılmıştır. Kalp yetersizliği tanılı toplamda 140 hasta (94 erkek, 46 kadın) çalışmaya dahil edilmiştir. İstatistiki analiz için SPSS programı kullanılmıştır.Bulgular: Ortalama depresyon skoru 9,5±3,9 ve ortalama anksiyete skoru 8,9±41 bulundu. Kesme puanı değerlerine göre hastaların %74’ünde depresyon ve %39’unda anksiyete semptomu saptandı. Depresyon ve anksiyete skoru NYHA sınıf 3-4’te diğer sınıflara göre daha yüksek bulundu. Hastalığın süresi ile depresyon arasında pozitif korelasyon saptandı. Hastaların %45’inde aynı zamanda Diabetes Mellitus (DM) tespit edildi. Günde 6 saatten az uyuyan hastaların depresyon ve anksiyete skorları daha yüksek bulundu.Sonuç: Çalışmamızda, kalp yetersizliği olan hastalarda yüksek oranda depresyon ve anksiyete semptomu saptanmıştır. Bu sonuçlar, kalp yetersizliği olan hastaların psikolojik semptomları için tedavi gereksinimi olduğunu göstermektedir.
Factors affecting breast milk and the effects of pacifier use on breastfeeding
Authors: YAHŞİ Aysun , ŞAYLI Tülin
Published: June 2022

Purpose: In this study, we aimed to determine the sociodemographic factors breastfeeding, pacifier use, the problems that may experience in breastfeeding, show effect of pacifier use on breatsfeeding.

Material and Methods: A questionnaire was applied by 349 mothers with babies between 24-60 months.

Results: The breastfeeding rate was 97%. Increasing week of birth, male gender, being first and/or only child, increasing maternal age, fathers’s support for breastfeeding, long maternity leave, increase the duration of breastfeeding; low birth weight, breastfeeding of siblings less than 6 months, high education level of mothers, pregnancy maternal smoking, early initiation of formula, pacifier use adversely affected breastfeeding. The pacifier use was 41,8%, the duration was 18±10,22 months. Pacifier use decreased breastfeeding, it increased the risk of weaning before 6 months by 5,1 times.

Conclusion: To increase duration of breastfeeding, mothers should be supperted, early initiation of additional food, formula, pacifier’s negative effects use on breastfeeding should be explained.
Immediate Effect of Dry Needling on the Viscoelastic Properties of a Trigger Point on the Infraspinatus Muscle Measured with MyotonPRO
Authors: Roch Mélanie , Morin Mélanie , Gaudreault Nathaly
Published: June 2022

Purpose: This article investigates the immediate effects of a dry needling (DN) puncture on the viscoelastic properties (tone, stiffness, elasticity) of a trigger point (TP) in the infraspinatus muscle in non-traumatic chronic shoulder pain. Method: Forty-eight individuals with non-traumatic chronic shoulder pain were recruited. The presence of a TP in the infraspinatus muscle was confirmed by a standardized palpatory exam. The viscoelastic properties were measured with a MyotonPRO device at baseline (T1), immediately after DN (T2), and 30 minutes later (T3). A DN puncture was applied to the TP to obtain a local twitch response while performing the technique. Results: Analyses of variance showed significant decreases in tone ( p < 0.001) and stiffness ( p = 0.003) across time after the DN technique. Post hoc tests revealed a significant reduction in tone and stiffness from T1 to T2 ( p ≤ 0.004) and no significant changes from T2 to T3 ( p ≥ 0.10). At T3, only stiffness remained significantly lower compared to T1 ( p = 0.013). Conclusions: This study brings new insights on the immediate mechanical effect of DN on tone and stiffness of TPs. Whether these effects are associated with symptom improvement and long-term effects still needs to be verified.
Replacement for Hard Chrome Plating in Printing Machinery
Authors: Wasserman C. , Boecking R. , Gustafsson S.
Published: June 2022

Airline and printing industry are looking for new techniques to replace electrolytic chrome plating in their machinery because of the toxic and carcinogenic characteristics of hexavalent chromium used in the ECP. Hard chrome platings are compared to thermal sprayed coatings and different techniques are shown. The article gives examples of Hard chrome replacement in printing applications, shows activities of government, airline and textile industries. Different types of coatings, produced with different spraying techniques, are compared in wear and corrosion tests. The results lead to an economical evaluation of HVOF sprayed alternative coatings and gives a hint to the HCAT-Program.
In Vitro Changes on High-Pressure Plasma Sprayed Hydroxyapatite Coatings
Authors: Español Pons M. , Khor K.A. , Cheang P. , Guipont V. , Jeandin M. , Llorca-lsern N.
Published: June 2022

The aim of this paper is to study the behavior of two different sets of as-sprayed coatings obtained from two different starting HA powders, in a defined simulated body fluid (SBF) for a period of 28 days. Spray-dried hydroxyapatite (SDHA) and spheroidized hydroxyapatite (SHA) were the two selected powders. A Controlled Atmosphere Plasma Spraying system (CAPS) was use for the production of the coatings. Effect of pressure and surrounding atmosphere during the spraying of the coatings, were also evaluated. During the in-vitro test, dissolution of the coatings and precipitation of a poorly crystallized apatite in a preferential crystallographic orientation ([001] direction) was observed for the two sets of coatings. Dissolution of the coatings was measured by: 1) weighing the specimen before and after soaking and 2) by measuring the calcium ion concentration in the SBF solution with the Inductively Coupled Plasma-Atomic Emission Spectrometer (ICP-AES). Scanning Electron Microscopy (SEM) exposed the morphology of the coatings and X-Ray diffraction (XRD) and Fourier Transform Infrared Spectrometer (FTIR) revealed their structure and composition.
Production of Superplastic Foils by Thermal Spraying
Authors: Wilden J. , Wank A.
Published: June 2022

Thermal spraying is widely used to produce corrosion and wear protective coatings or thermal barrier coatings. Only some applications with electrical or chemical function of the coatings are developed to a state of the art for industrial use. A lot of effort is done on the production of SOFC by thermal spraying. No use is made of the high potential of thermal spray processes to build up free standing bodies or semi finished parts. Foils or thin sheets for microtechnology might be parts producable by thermal spraying. Superplastic materials are of special interest for the microtechnology, as they can be shaped on a microscopic scale without elastic reforming. The paper deals with the metallurgical and process requirements for superplastic sheet production, the choice of feasible alloys and the first experimental investigations. The process parameter field for LPPS is determined and the produced sheets are characterized at room temperature concerning their microstructure, morphology and hardness.
Process Modelling to Optimise the Structure of Hollow Zirconia Particles for Use in Plasma Sprayed Thermal Barrier Coatings
Authors: Klocker T. , Clyne T.W. , Dorfman M.R.
Published: June 2022

A numerical finite difference model has been developed to treat the transfer of heat and momentum between a gas environment and a particle injected into it. The model is based on an explicit solution scheme for the thermal field and explicit treatment of the momentum exchange. The latent heat associated with phase changes is simulated via a post-iterative heat accumulation scheme. Particle-gas heat transfer is represented by a heat transfer coefficient, which is a function of relative gas velocity. The validity of the model is confirmed via comparisons between predicted behaviour and previously-published experimental data for thermal histories and particle trajectories. Comparisons are also presented with predictions from previously-developed models. Results are then presented for the behaviour of hollow zirconia particles, with particular attention being paid to in-flight melting characteristics. It is shown that there is an optimum combination of particle size and wall thickness for the promotion of efficient melting, for a given gas flow and temperature field.
Comparative Study of Different Sealing Methods for Thick Thermal Barrier Coatings
Authors: Ahmaniemi S. , Tuominen J. , Vuoristo P. , Mäntylä T.
Published: June 2022

Zirconia based, 8Y2O3-ZrO2 and 22MgO-ZrO2 thick thermal barrier coatings (1000µm), were studied with different sealing methods for diesel engine applications. Aim of the sealing procedure was to improve hot corrosion resistance and mechanical properties of porous TBC coatings. The surface of the TTBCs was sealed with two different methods, phosphate based sealing treatment and laser glazing. The thickness of the densified top layer in all cases was 50-400µm. XRD analysis showed some minor phase changes and reaction products caused by phosphate based sealing treatment and some crystal orientation changes and phase changes in laser-glazed coatings. The porosity of the outer layer of the sealed coating decreased in all cases, which led to increased microhardness values. The hot corrosion resistance of TTBCs against 60Na2SO4 - 40V2O5 deposit was determined in isothermal exposure at 650°C for 200 h. Corrosion products and phase changes were studied with XRD after the test. Short-term engine test was performed for the reference coatings (8Y2O3- ZrO2 and 22MgO-ZrO2) and for the phophate sealed coatings. Engine tests were performed at the maximum load of the engine and it was aimed to evaluate the thermal cycling resistance of the sealed coatings. All the coatings passed the engine test, but some vertical cracks were detected in the phosphate sealed coatings.
Influence of a Multi-Gas Mixture on the Performance of a HPPS Plazjet System for a Thermal Barrier Coating
Authors: Dhers J. , Goubot N. , David T. , Baudoin J. , Barthelet M. , Huet J. , Ducos M.
Published: June 2022

The Plazjet system usually works with a binary gas mixture of nitrogen and hydrogen for the deposition of a thick TBC (NiCrAlY as a bond coat and Zirconia as a top coat). In order to improve the performances of our spraying device and ensure good quality coating, different experiments were conducted. The substitution of N2 or the classical binary mixture N2/H2 respectively by a binary N2/He, and a ternary gas composition N2/H2/He leads to an evolution of the deposition efficiency and quality coating. In order to optimise the various ratio in the gas mixture, the evolution of experimental parameters such as voltage were analysed.
Manufacture of SiC Composite Coatings by HVOF
Authors: Wielage B. , Wilden J. , Schnick T.
Published: June 2022

The main application of HVOF processes is the production of wear and/or corrosion protective coatings based on cermets (e.g. WC-Co). To reduce the weight of the sprayed volume, to increase the oxidation resistance and to reduce the costs of consumables SiC based cermets are of particular interest. The outstanding mechanical, thermal and chemical properties of SiC have made this material attractive for thermal spray applications. Thermal spraying of pure SiC is impossible, because of its decomposition at elevated temperatures. The development of suitable alloys as metallic binders enables the wetting of the SiC particles with reduced reactivity between the matrix and the hard particle during the thermal spray process. In the present work starting from the metallurgical concept of the metallic matrix to the production route from the atomization of the metallic matrices, the spray drying and sintering as well as the processability of the composites is discussed. The coatings are characterized concerning porosity and SiC content using optical and scanning electron microscopy, digital image analysis, X-ray diffraction and micro hardness testing. The wear resistance of the coatings is determined by oscillating wear test. Microstructure and performance of the SiC composite coatings are discussed with respect to technical applications.
Properties of HVOF Sprayed Multi-Scale Polymer/Silica Nanocomposite Coatings
Authors: Twardowski T.E. , Reilly M. , Knight R.
Published: June 2022

The high velocity oxy-fuel (HVOF) combustion spray technique has previously been shown to be an excellent solution for depositing crystalline matrix nano-reinforced polymer coatings. The use of multiple scales of reinforcement is expected to improve the load transfer from the larger reinforcing particles to the matrix through the mediation of the smaller particles. The initial step in developing multi-scale coatings is studying the effects of reinforcement size on distribution and properties. Nylon 11 coatings filled with silica particulates of 7 nm, 20 nm, 10µm and 100µm have been produced using the high velocity oxy-fuel (HVOF) combustion spray process. The physical properties and microstructure have been evaluated as a function of the reinforcement size. Nylon 11 was co-milled with the fillers to a 10% volume fraction. The filler was agglomerated at the splat boundaries in the final coating microstructures. All filled coatings had significant changes in x-ray pattern relative to pure nylon 11 coatings, indicative of both increased crystallinity and changes in crystal structure. Coatings containing the smallest reinforcements exhibited improvements of 40 % in scratch and 84 % in wear resistance above those containing the largest reinforcement particles in coatings with nominal 10 vol. % of hydrophobic silica. This increase appeared to be primarily due to filler addition and increased matrix crystallinity.
Kinetic Powder Compaction Applying the Cold Spray Process—A Study on Parameters
Authors: VIcek J. , Huber H. , Voggenreiter H. , Fischer A. , Lugscheider E. , Hallén H. , Pache G.
Published: June 2022

Supersonic, two-phase flow of a gas/particle mixture directed towards a substrate may enable the deposition of "cold" particles onto a "cold" substrate under certain conditions. The method is commonly known as Cold Gas Dynamic Deposition or Cold Spray. Current research shows that copper can be deposited within a wide range of parameters and velocity regimes, whereas the deposition of other materials may involve difficulties depending on the material properties and substrate characteristics. Although particle velocity is recognized as being the key factor in the deposition of particles with the cold spray process, it alone cannot describe the state of the particle prior to and during impact. A simple analysis shows that the impulse of particles with equal particle velocity and size depends significantly on its density. For common engineering metals, an interval varying by up to a factor of 5 is possible considering, for example, magnesium and molybdenum. The impact force, directly dependent on the particle's impulse, governs the pressures generated during impact. In a simplified calculation, pressure values of around 3000 MPa can be very easily determined. While the particle impulse accounts for the degree of interaction - partial or complete deformation - the particle's and the substrate's lattice structure and its capacity to deform determine the type of particle substrate interaction. Depending on these properties, the substrate, the particle or both will be deformed. Evaluating impact experiments shows distinct differences between the impacts of copper, steel and aluminum particles on aluminum and steel substrates. The paper presented may be seen as a contribution to the discussion of a theory to evaluate coating and substrate combinations prior to spraying in order to predict bonding and coating build-up or to offer guidance concerning the optimum parameter set for deposition.
Microstructure and Properties of Cold Spray Nickel
Authors: Decker M.K. , Neiser R.A. , Gilmore D. , Tran H.D.
Published: June 2022

Electroplated nickel can be used to fabricate miniature components such as gears, linkages, and other two-dimensional mechanical structures. This process produces excellent parts, but it is slow and somewhat expensive. Because cold spray produces low oxide-content, high-density deposits at a high rate, cold spray processing might be a viable alternative to electroplated nickel components. In addition, cold gas-dynamic spray can process materials, such as stainless steel and aluminum, which can not be electroplated. The purpose of this study was to evaluate the mechanical properties of cold spray nickel in the as-sprayed and heat treated conditions, then compare them to those of bulk nickel and electroplated nickel. Characterization of freestanding structures is subjective since the final product of any thermal spray process produces a material unlike any other material formed by conventional techniques. Specifically, this investigation determines the mechanical characteristics of nickel, through metallographic imaging and tension testing. Metallographic imaging showed that as-sprayed nickel has slightly more voids than the heat-treated structures. Tension tests of the as-sprayed nickel showed little plastic behavior, while a heat treatment gives much more ductility without compromising ultimate strength.
Process Study of Thin Coating Deposition by Low Pressure Plasma Spray
Authors: Ma X.Q. , Borit F. , Guipont V. , Jeandin M.
Published: June 2022

In the present work thin Al2O3 coating was obtained mainly by low pressure plasma spray (LPPS). Low-porosity and low-roughness deposits resulted from the optimized spray conditions, i.e. plasma parameters, grit blasting, powder feed rate and specimen rotation speed. Results showed that LPPS processing was highly beneficial for densifying the ceramic coatings, especially when coupled to a moderate powder feed rate. Coating average surface roughness (Ra) ranged from 1.5 to 2.5 µm for a coating thickness of less than 30µm and an original substrate Ra of 1.1µm. The spray conditions were optimized particularly for a low feed rate and a high specimen rotating speed to lower surface roughness. Moreover, a specific atmosphere/temperature control device was developed (using local gas injection close to the specimen to be coated). This resulted in improving cooling efficiency, which reduced microcracking in the deposits. Mechanical pull-off adhesion test was also carried out to evaluate these low-roughness thin coatings. Adhesion was shown to be satisfactory for direct coating (i.e. without any bond coat) of a low-roughness (Ra=1.1µm) AISI 316L substrate.
Role of Some Fuel Gases on Properties of HVOF Metallic Coatings
Authors: Gourlaouen V. , Verna E. , Kho K. , Quek P.S.T.
Published: June 2022

HVOF spraying process is widely used to improve component life in service due to the high bond strength of the coatings, which is a result of the high particle velocity upon impact, and consequent low coating porosity. However, many parameters can affect metallic coatings properties, especially unmelted particles and oxidation level. Flame parameters, such as calorific power, combustion ratio and temperature, are of prime importance. Moreover, the fuel gas employed in this spraying process can lead to various coating properties and deposition efficiency. The aim of this work was focused on the influence of some fuel gases, namely propane, propylene (LPG) and hydrogen, on stainless steel coating characteristics. A specific domain common for those three gases was determined in order to effectively compare those gases with the same flame parameters. Flame characteristics were computed using a simple model for all the fuel gases considered. Temperature as well as calorific power were fixed. For different substrate temperatures, obtained through a special CO2 cooling nozzle system, richness was varied from 1.4 to 1.6. Microstructure investigation as well as oxide content and microhardness measurements were conducted. For the same kinetic torch parameters, thickness-per pass gave an idea of the deposition efficiency. In the range studied, deposits properties were quite similar for both LPG fuel gases. Hydrogen led to better characteristics in term of oxide content, although its deposition efficiency was a bit lower. A general law was established to link oxide content within the coatings to the flame parameters. A reasonable regression analysis was obtained for all the coatings sprayed. The combination of cooling efficiency (i.e. CO2 flow rate) and flame characteristics (i.e. interaction of the particle in flight) led to a good correlation. These correlations were further verified by spraying another metallic powder, namely Inconel 625.
Surface Modification of Plasma Sprayed Coating by Using YAG Laser Equipped With a Kaleidoscope
Authors: Chwa S.O. , Ohmori A. , Yang H. , Zhou Z.
Published: June 2022

Thermal spraying technique has been widely applied for the production of ceramic protection layer on metals that used in various hostile environments. However, all sprayed coatings have defects such as connected pores and unmelted particles, which deteriorate coating properties. To improve the properties of sprayed coatings, a lot of approaches have been undertaken such as laser irradiation, seal sintering with liquid alloys and sol-gel infiltration technique. Lasers are promising technological tools due to its speedy treatment and simplicity of process control. Moreover, laser treatment technology enables not only the post-treatment but also the pre and simultaneous treatment by combining with spraying process. Generally, wide beams of as uniform as possible are preferred for use in laser surface treatment to obtain a uniform depth of melting, alloying or cladding and to cover a large area by partially overlapping of tracks. However, it is not easy to produce a uniformly treated coating by conventional laser treatment method as desired. To obtain a near-uniform beam intensity for practical laser irradiation, a kaleidoscope was installed in a conventional YAG laser. In this research, laser beam properties of YAG laser equipped with a kaleidoscope and its effect on surface modification of plasma sprayed zirconia coatings and WC-Co system coatings prepared by HVOF spraying was investigated.
Alumina Duplex Coating by Multiprocesses: Air Plasma Spraying and Plasma Enhanced Chemical Vapor Deposition
Authors: Haure T. , Denoirjean A. , Tristant P. , Hidalgo H. , Leniniven C. , Desmaison J. , Fauchais P.
Published: June 2022

Thick alumina coatings produced by Air Plasma Spraying have an interconnected porosity, thus the use of these coatings in oxidizing or corrosive environment is not suitable. In this paper, a study is developed in order to limit this problem on metallic substrates. It consists in using two successive techniques: APS and PECVD. Two parameters have been shown to be important: the roughness and the preheating temperature. Two types of duplex (PECVD coating as top coat or as bond coat) have been achieved on two substrates (TA6V and stainless steel 316L). The optimization of each process has shown that the substrate has to be grit blasted and preheated (360°C for PECVD and 250°C for APS). This study has revealed that a good (36 ± 5 MPa) APS coating adhesion was obtained on smooth TA6V substrates (due probably to a chemical reaction between TiO2 and alumina) while for stainless steel substrates, the Ra has to be at least 2µm to achieve 66 ± 5. When observing the first APS splats sprayed on the PECVD alumina smooth layer, they exhibited a specific appearance: low flattening degree (about 2 against 5 on metallic substrates) with most of the alumina in the splat rim or some sort of lace morphology. However, as a whole, the adhesion of the APS coating on the PECVD one was excellent: 60 + 4. An electrochemical method has shown that the PECVD layer on APS coating has reduced drastically its open porosity.
Study of Microstructure and Atomization Forming Process of Ultrasonic Arc Sprayed TiAI Alloy Coatings
Authors: Wang H. , Li P. , Guo Q. , Yang H.
Published: June 2022

By means of homemade ultrasonic arc spraying equipment patented, under the condition of the optimum arc spraying parameters, TiAl alloy coatings were manufactured on the aluminum alloy (LY12) matrix surface. The ultrasonic arc spraying forming process and microstructure of TiAl compounds alloy coatings were investigated by the color metallurgical microscopy, SEM, XRD, EPMA and chemical composition quantitative analysis (ICP). The results showed that TiAl compounds composite coatings can be synthesized by ultrasonic arc spraying system, the coatings possess typical lamella character, consist of TiN (or TiO), TiAl, Ti0.7.1.1 Al(N,O), Ti2.4Al(N,O), Ti2.4Al and aluminum alloy solid solution.
A Microstructural Study of HVOF and VPS Sprayed MCrAlY Coatings
Authors: Nuutinen S. , Vuoristo P. , Ahmaniemi S. , Mäntylä T. , Takeuchi J.
Published: June 2022

The aim of the present work is to study the microstructure of high temperature oxidation and corrosion resistant MCrAlY coatings prepared by high-velocity oxy-fuel (HVOF) spraying and to compare them to vacuum plasma sprayed (VPS) MCrAlY coatings. In this work, CoNiCrAlY, NiCoCrAlYTaReSiHf, and NiCrAlY coatings were prepared on nickel based superalloys by VPS spraying and by two types of HVOF spray process (DJ Hybrid 2600 and JP-5000). The influence of spray parameters, i.e. oxygen flow rate and spray distance, in one of the HVOF processes (DJH 2600) on coating structures and properties were studied also in more detail. The coatings sprayed with different spraying processes were studied in their as-sprayed state and after heat-treatment by optical microscope and scanning electron microscopy (SEM). The results show that selection of appropriate particle size of the spray powder has marked importance in the HVOF process; presence of fine powder particles produce oxides in the coatings and ease clogging of the nozzle in the HVOF gun. The use of appropriate size distribution of the spray powder enables preparation of HVOF MCrAlY coatings with low oxide content and dense structure. The oxide content of HVOF sprayed coatings should be kept as low as possible in order to make the post heat-treatment active in producing a dense microstructure with correct phase structure. The oxide content can be controlled e.g. by flame temperature control by means of oxygen flow rate and by appropriate spray distance selected individually for each powder. Unacceptable high oxide contents in the as-sprayed structures tend to remain unchanged after heat-treatment, whereas well-developed coating microstructure and phase structure are obtained with HVOF sprayed coatings with low oxide content. Microstructures developed in heat-treated VPS and HVOF sprayed coatings are compared.
Optimisation and Monitoring of Spray Parameters by a CCD Camera Based Imaging Thermal Spray Monitor
Authors: Vuoristo P. , Ahmaniemi S. , Nuutinen S. , Mäntylä T. , Hämäläinen E. , Arola N. , Vattulainen J.
Published: June 2022

On-line monitoring of two thermal spray processes by means of an imaging diagnostic technique capable of measuring several spray particle properties, such as individual and average particle temperatures, velocities and number of particles with spatial distributions, was studied by using the Spray-Watch thermal spray monitor. Aim of the work was to demonstrate the capabilities of this novel monitor in quick optimisation of certain spray gun parameters to obtain desired particle characteristics in-flight, and hence desired coating structure and properties with high deposition efficiency. Examples are given in plasma spraying of Al2O3 and HVOF spraying of NiCoCrAlY.
Capture and Evaluation of HVOF Thermal Sprayed Particles by a Gel Target
Authors: Yamada H. , Yumoto H. , Kuroda S. , Fukushima T.
Published: June 2022

A new method to capture and evaluate the condition of thermal sprayed particles has been developed by using an agar gel target. HVOF sprayed Hastelloy C particles were collected by a gel target placed at the substrate position, i.e., 380mm downstream from the spray nozzle exit. In the surface layer of the target, a large number of fine particles were observed, whereas in the deeper part, globular particles were trapped. The ratio of particles in the surface layer with respect to the deeper part changed by spraying parameters. Furthermore, particles in the target were separated by cutting the gel, collected after resolving the agar, and then observed by SEM. Particles collected from the target's surface layer were fine particles (under 10µm) and fragments of dendritic crystals. These collected from the deeper part were mostly unmelted particles, some of which exposed dendrites. Results obtained by other techniques such as splat observation and in-flight diagnostics are compared with these results. It was concluded that by capturing thermal sprayed particles with a gel target, it is possible to visualize and quantify the melting condition of HVOF sprayed particles.
Proposal of New Criterion for Splashing of Thermal Sprayed Particle onto Flat Substrate Surface
Authors: Fukumoto M. , Nishioka E. , Nishiyama T.
Published: June 2022

In the collision of a liquid droplet onto a flat surface, a splashing parameter (K=We0.5Re0.25) has been used to evaluate the flattening behavior, and a critical value of K (KC) was introduced as a criterion for splashing. In order to evaluate K of thermal sprayed particle, in-flight measurement for the velocity and temperature of the particle was conducted in this study. As a flattening pattern of the thermal sprayed particle changed significantly with a substrate temperature, the transition temperature (Tt) was also measured by changing the substrate temperature. Both K and Tt showed a tendency of monotonous decreasing with increasing the spray distance and a strong linearity was recognized in a K-Tt relationship. This straight line corresponds to a critical value for the splashing. However, as the influence of substrate temperature on the flattening is essentially independent of K, a new criterion for the splashing in the flattening of the particle was proposed in the study. That is, a splashing parameter on flattening was proposed, which considers the ratio of the flattening velocity to the impact velocity of the particle.
Impact, Deformation and Cooling Down of Atmospheric Induction Plasma Sprayed Ceramic Particles and Their Influence on Coating Properties
Authors: Dzur B. , Nutsch G.
Published: June 2022

In the present work ceramic particles (Al2O3, YSZ) are sprayed onto steel substrates using a radio frequency inductively coupled atmospheric plasma spray process (IC APS). Because of the low plasma velocity and the large plasma volume large particles can be completely melted. The particles reach the substrate with low velocities (in the order of 10 m/s). So, a special kind of deformation can be observed. Some characteristic values of impact and deformation are also quite different from some other thermal spraying technologies. Of course, that has an strong influence on the coating properties. It is shown, that a high kinetic energy of impinging particles is not an essential assumption for a high bond strength and a low porosity of the coatings. IC Plasma sprayed particle splats are investigated and compared with DC and HVOF sprayed ones. The influence of the particle impact and deformation on the coating properties is demonstrated. It is shown, that in spite of the low particle velocities coatings can be sprayed by IC APS with comparable quality, but with quite different coating properties such as the crystalline structure.
Application of CAD to CFD for the Wire Arc Spray Process
Authors: Bolot R. , Bonnet R. , Jandin G. , Coddet C.
Published: June 2022

In view of its advantages (simplicity, low cost, high deposition rate), the wire arc spray process has become a widely used technology for the spraying of metals. Nevertheless, numerous parameters (gun design, atomizing gas nature, velocities, pressures, ...) may have a significant influence on the quality of the produced coatings. One of the major problems related in the literature concerns the poor control over the spray pattern; the understanding of this phenomenon has thus become essential for further improvements. In the present study, a special feature of the PHOENICS commercial code (from CAD to CFD ) was used to produce a 3D simulation of the flow within the gun and outside. This method was especially useful in view of the complex geometry of the TAFA 9000 gun, which was investigated. The results show the presence of a highly asymmetric external jet.
Modeling of the Acceleration and Behavior at Impact of Ceramic Suspension Droplets in Aerosol Flame Spraying
Authors: Poirier T. , Vardelle A.M. , Elchinger M.F. , Vardelle M. , Grimaud A. , Vesteghem H.
Published: June 2022

Aerosol Flame Spraying (A.F.S) combines the atomization of a colloidal suspension with the lateral injection of the aerosol in a flame. The aerosol droplets are partially dried when crossing the flame and deposited as a coating onto a substrate. The coating is then consolidated by a heat treatment. In this paper, a modeling of the trajectories, acceleration and vaporization of the droplets is presented. This model supposes that the droplets dry at a constant rate until they impact onto the substrate. It predicts the size and water content of droplets at impact. From these data and hydrodynamic properties (viscosity, surface tension, contact angle) of the suspensions, the morphology and size of the lamella deposited on the substrate can be determined by using classical impact models. A colloidal monoclinic zirconia suspension with a 60-nm particle diameter is used in this study. In spite of the complexity of the mixing of suspension spray and flame, and the diversity of the thermal histories of the droplets, the observation of the latter after impact shows that the results of the model are quite consistent with measurements.
Finite Element Analysis on Residual Stress in a Plasma-Sprayed Functionally Graded Thermal Barrier Coating
Authors: Limarga A.M. , Widjaja S. , Yip T.H.
Published: June 2022

Thermal barrier coating (TBC) structures composed of Al2O3 and ZrO2 with different chemical compositions on the NiCoCrAlY bondcoat are proposed to improve the oxidation resistance of TBC systems. The concept of functionally graded materials (FGM) was applied to manage residual stresses due to sharp interface between dissimilar materials that can lead to a premature failure of the TBC system. A numerical study using finite element analysis was performed to investigate the effects of system architecture on the residual stresses developed in Functionally Graded - Thermal Barrier Coatings (FG-TBCs) and in a typical duplex TBC comprising of NiCoCrAlY bondcoat and ZrO2 topcoat. The effects of different cooling rates and substrate preheating process on the residual stress distribution were also studied. The results showed that lower cooling rate and substrate preheating process reduce stresses within the duplex coating. In addition, the incorporation of Al2O3 interlayer results in a manageable level of residual stress. Stresses at critical locations are reduced, and hence contributing to an increase in resistance to the interfacial crack. The possibility of surface cracks is also reduced since the radial and tangential stresses within the FGTBC system are lower than those of the duplex system. It was found that the thickness of Al2O3 layer and the number of graded layers introduced between Al2O3 and ZrO2 do not significantly affect the stress distribution. To provide adequate comparison to the computational results. X-ray diffraction was used to assess the in-plane residual stresses on the coating surface.
Deposition Model of Thermal Spray Coatings
Authors: Ghafouri-Azar R. , Mostaghimi J. , Chandra S.
Published: June 2022

A three dimensional model of coating formation has been developed. Using the model we are able to simulate coating formation by deposition of large numbers of droplets. The properties of impacting particles are assumed to vary stochastically using a normal probability density function. Splat curl up is assumed to be the source of porosity formation. The model is able to predict coating porosity, thickness and roughness as a function of spray parameters.
Mechanical and Electrical Properties of Al2O3–TiO2 Coating as Electrical Insulator
Authors: Nakamichi M. , Kawamura H.
Published: June 2022

In a fusion reactor (i.e. ITER), the use of a ceramic coating on structural material (SS3I6LN-IG) has been considered as electrical insulator. Al2O3 including TiO2 (Al2O3-TiO2) is one of most promising materials as coating from a point of high electrical resistivity and so on. However, crack and peeling occur by difference of thermal expansion between substrate material and coating material. Therefore, 80Ni-20Cr was selected as the undercoating between SS316LN-IG substrate and Al2O3-TiO2 coating. In this characterization, Al2O3-3%TiO2 and Al2O3-13%TiO2 were used as ceramic coating material. 80Ni-20Cr undercoating was fabricated by atmospheric plasma spray method. The thickness of 80Ni-20Cr was 50µm. Al2O3-3%TiO2 and Al2O3-13%TiO2 were fabricated by atmospheric plasma spray method. Thickness of these ceramic coatings are 200 and 500µm. From the results of out-of-pile test, it was clear that Al2O3-3%TiO2 and Al2O3-13%TiO2 coating had a good mechanical and electrical properties.
Thermal Sprayed Hard Cr3C2-NiCr Coatings for Wear Protection
Authors: Valente T. , Bartuli C. , Tului M.
Published: June 2022

Thermal sprayed ceramic coatings play an important role in those industrial applications where exceptional erosion and wear resistance are required. In particular, nickel-chromium based coatings containing chromium carbide particles dispersion are widely used when environment temperature rises up to 800°C. Thick Cr3C2-NiCr coatings were produced with two thermal spray processes: Air Plasma Spray (APS) and High Velocity Oxy-Fuel (HVOF). Two different powders have been selected as starting materials. Their dimensional and morphological properties were assessed to verify their sprayability, both in terms of flowability and deposition efficiency. For both APS and HVOF processes, most deposition parameters were selected, after preliminary spraying tests, on the basis of statistical analysis of results, in terms of coating density, hardness and substrate-coating interface quality. The tribological properties of the coatings were evaluated in order to investigate the influence of the deposition process on the behavior of coatings under wear conditions
Scratch Testing of Nanocrystalline Alumina+13%Titania+Zirconia
Authors: Gold M.R. , Berndt C.C.
Published: June 2022

This work examines nanocrystalline thermal spray coatings prepared under several power and stand off distances. The coating material was nanocrystalline alumina + titania and zirconia (ATZ) powder mixture deposited using an air plasma spray process. The experimental design employs a full factorial method totaling four samples. The mechanical properties of four coatings were compared via scratch and hardness testing. The scratching process was monitored for transverse loads during the test and the variation in load monitored. The profiles of scratches were analyzed using white light interference profilometry and studied further via SEM. The results indicate that the microstructure reflected features observed in the scratch test. It was also shown that the scratch process and morphology depend on the normal load and spray process.
Development of Ultra Thin Carbide Coatings for Wear and Corrosion Resistance
Authors: Fischer F.F. , Dvorak M.D. , Siegmann S.
Published: June 2022

The increasing demand of the industry for high quality coatings with a low cost aspect has led to the development of ultra thin, nearby finishing free carbide coatings. The R&D work performed for this publication was focused on the tailoring of carbide powders together with the development of a new generation of HVOF-Systems working on higher combustion chamber pressures. An as-sprayed surface roughness of less than 1,5µm has to be envisaged for a thin nearly finishing free coating. Therefore, the starting powder has to have fine particles size with a homogenous distribution of carbides and matrix metals. To ensure the corrosion resistance, the matrix metals have to be completely alloyed and the coatings have to be dense. The used HVOF-System must be able to feed and spray these fine powders without any blockage of the powder feeder or nozzle clocking. The coating quality has to fulfil the requirements of hardchrome plating as wear and corrosion resistance is concerned. The low cost level of thin hard-chrome coatings shall be matched. The suitability for using this coating on applications like hydraulic cylinders has been proven. Generally, this technique of thermal spraying can be used as a hard-chrome alternative as well as for new applications where thermal spraying was not put into account due to cost and technical reasons. The aim was to fill the gap between thin film technologies as PVD or CVD techniques and conventional thermal spraying. The new technology enables the industry to coat large components with nearly no restrictions in size and for competitive prices.
On-Line Microstructure and Property Control of a Thermal Sprayed Abrasive Coating
Authors: Nylén P. , Wigren J. , Idetjärn J. , Pejryd L. , Friis M. , Moretto P.
Published: June 2022

A process control tool has been developed for air plasma spraying of a NiAl (bond coat) and Al2O3 (top coat) coating systems. The process is employed at Volvo Aero Corporation for abrasive purposes, such as knife-edge applications on compressor parts. In-flight particle temperatures, velocities and diameters were measured by the DPV2000 system. Several samples were sprayed and the coating microstructures were evaluated using Image Analysis techniques on optical and scanning electron microscope images. Top and bond coat thickness, oxides, porosity, grit blast residues, delaminations, surface roughness (on top, bond and substrate) and tensile strength were evaluated. Statistical regression analysis was then used to establish relationships between process parameters (i.e. current and primary gas flow), particle in-flight characteristics (i.e. velocity and temperature), microstructure properties, and mechanical properties. The equations derived were finally used for development of a tool, which can be used by the operator for on-line monitoring and control of the coating characteristics based on information of the current particle inflight characteristics. The tool makes it possible to continuously adjust the process set points, ensuring a high reproducibility and stability of the process.
Some Considerations for the Routine Testing of Thermal Sprayed Coatings
Authors: Wigren J. , Täng K.
Published: June 2022

Revealing the true properties is of utmost importance for the optimized use of thermal sprayed coatings and for the realization of the ultimate spray booth. The necessity of the true properties for a successful correlation as well as development of process windows for on-line control cannot is emphasized. Only the true properties can be expected to correlate to the spray parameters or the particle properties in the flame. What is actually meant when stating the following? - The coating has 5% porosity - Tensile bond is 50MPa - Hardness is 1000HV - Coating thickness is 100 nm Different loopholes during the steps of metallographic preparation, hardness and tensile bond strength testing are highlighted and discussed. The microstructure of a thermally sprayed coating typically consists of a multiphase matrix (often a mix between hard, soft and amorphous), pores, oxides, delaminations, cracks, grit residues and unmelted particles. Due to this complexity in the structure there are a number of possible errors that often can be made in metallographic laboratories. Several examples and explanations are given. It is shown that improper handling in the materials laboratory may lead to smearing and pullouts etc. This will ruin the results and effectively hide the true microstructure. Furthermore the use of different epoxies and curing methods effectively varies the tensile bond strength test results by more than 300% for various coatings. By using different preparation routines the micro hardness can be varied by more than HV0.3 100.
Online Quality Control of Thermally Sprayed Coatings
Authors: Dvorak M. , Florin C. , Amrhein E.
Published: June 2022

An industrial and cost-effective online quality control method for thermally sprayed coatings will be presented. A new concept in pulse-thermography allows online, during the spraying process, the non-destructive evaluation of coated surfaces. This technique employs a heat source that produces a heat impulse. The impulse is directed toward the examined surface and the from the surface reflected and/or emitted signal is collected by an infrared-camera and subsequently treated in a computer. It will be demonstrated that the spraying process itself can be used as a heat source. In principle, the fading behavior of the signal captured by a high speed infrared camera is observed, or else the progression of the induced heat wave within the coating. Differences in coating thickness, coating and adhesion defects, microstructural changes, an aggregation of pores as well as oxide or metallic inclusions provoke a significant change in the signal intensity and are therefore detected. Pulse-thermography enables the non-destructive assessment of the quality of thermally sprayed coatings. A coated part can be examined to check if the desired coating structure has been successfully attained or if and where there are any areas with critical deviations in respect to coating thickness or coating microstructure. The simple set-up allows the integration of the technique in the production line.
Thermal Coating In Europe: A Business Prospective
Authors: Ducos M. , Durand J.-P.
Published: June 2022

The authors carried out in 1999 a multiclient market research covering the Thermal Coatings business in Europe. This work has allowed to obtain detailed business facts relative to the industry and has provided an in-depth understanding of applications, markets, competition, key factors for success and industry structure. Thermal coatings are defined here as coating parts by hardfacing (e.g. MIG, TIG, PTA, laser...) or thermal spray (flame, arc, plasma, HVOF...). This study also provided a further opportunity to investigate about present business issues and to provide a fresh look into growth opportunities. This presentation intends to provide the scientific community with a summary of this business analysis and to stress business issues and factors found to constrain business growth today. We do expect that a more carefully focused teamwork between independent R&D and the supply chain could significantly accelerate the growth of the Thermal Coatings business in the future.
Process Window for Plasma Spray Processes
Authors: Friis M. , Persson C.
Published: June 2022

A method for creation of a process window for on-line monitoring and controlling of the particle velocity and temperature during plasma spraying in order to enable desired coating microstructure is presented. The desired coating is specified by determination of the ranges within which the different microstructure features and the powder deposition efficiency are allowed to vary. Multiple linear regression models, relating the particle velocity and particle temperature to the coating criterions is utilized to successively delimit the particle velocity and temperature ranges. This results in a process window, giving the limits within which the particle velocity and temperature are allowed to vary in order for the desired coating to be produced.