bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal Spraying of Bioactive Polymer Coatings for Orthopaedic Applications
Authors: Chebbi A. , Podporska J. , Stokes J. 
Published: November 2022

Abstract
This research aims at introducing new biodegradable/non-biodegradable materials (biopolymers) to the existing Hydroxyapatite (HA)-titanium combination or as a single coating in order to overcome some of the limitations of HA coatings. Biopolymers can act as drug carriers for a localised drug release following implantation; they can also have a structural role by improving the mechanical performance of implants at the bone –implant interface. The proposed materials consisted of biodegradable and non-biodegradable polymers widely used as drug delivery systems: polymethylmethacrylate and polyhydroxybutyrate 98%/ polyhydroxyvalerate 2%. The method used to apply the polymeric powders was oxygen/acetylene flame spraying, due to its superior mechanical advantages over other techniques. Screening tests were used to determine the suitable range of spraying parameters, followed by optimisation to understand of the effects of spraying parameters on coating characteristics (thickness, roughness, adhesion, wettability), in order to obtain an optimal coating design. The polymers were sprayed onto bare titanium substrates. FTIR results showed that the coatings underwent little chemical degradation. Biocompatibility tests showed that cells proliferated well on flame sprayed polymer coatings, which confirms that the coating technique used did not affect the biological performance of the material.
Polymers in Thermal Spray
Authors: Grimenstein L. F. 
Published: November 2022

Abstract
Over the year’s polymers have been used in thermal spray coatings. The most known usage is as a polymer used to seal porosity in thermal spray materials. The sealers mostly used do not really work because they do not penetrate very far into the coating. Once the coating is machined or ground the sealer is gone and we have a porosity coating due to fail. One major sealer resin system used, is Phenolic as the resin, that resin is older than most of the audience and loaded with flammable acetone. It also is not a high temperature material nor does it last long since it is a rigid material and does not expand or contract. The old sealers mostly had solvent systems in them and were replaced with a water born polymer. However, our industry has not kept up with the technology of resin based systems. Water systems sound good environmentally but it does not penetrate and really does not work well for this application. Later polyester was used with a ceramic filler to produce an abradable coating for the seal area for turbine applications. More recently higher temperature polymers were used to create a high temperature abradable coating. I want to show you some new polymeric materials that have done some new applications and also recommend additional work for the thermal spray industry for improved applications using the technology of tomorrow.
Surface Modification of Austenitic Thermal Spray Coatings by Low-Temperature Carburization
Authors: Wielage B. , Rupprecht C. , Lindner T. , Hunger R. 
Published: November 2022

Abstract
Thermal spray coatings of austenitic materials are mainly used under corrosive conditions. The relatively poor wear resistance strongly limits their use. A selective enrichment of the surface layer region with carbon by means of thermochemical heat treatment improves the residual stresses and increases the wear resistance. The interstitial deposition of carbon causes strong compressive residual stresses and a high surface hardness. The low process temperature of the thermochemical heat treatment avoids the precipitation of chromium carbide, whereas the corrosion resistance is not affected. Increases in the service life of existing applications or new material combinations with face-centred cubic friction partners are possible. In the absence of dimensional change, uniform as well as partial carbon enrichment of the thermal spray coating is possible. In comparative studies between carburized and untreated thermal spray coatings, the influence of the carbon enrichment on the coating properties and the microstructure was investigated. Carburized coatings demonstrate a significant improvement in adhesive wear resistance and an extremely high surface hardness. The cross section micrograph of the carburized coating shows the S-phase formation in the surface layer region. The depth profile of the carbon concentration was determined by GDOS analysis.
Effect of Laser Remelting on the Mechanical Behaviour of Inconel 625 Cold-Sprayed Coatings
Authors: Vezzù S. , Rech S. , Trentin A. , Poza P. , Múnez C. J. , Garrido-Maneiro M. A. 
Published: November 2022

Abstract
Ni base overlay coatings are being used to protect metallic engineering components in extreme conditions and actually traditional thermal spray deposition technologies such as Air Plasma Spraying (APS) and High Velocity Oxy-Fuel (HVOF) are mainly used to deposit these materials. However, Coldspray is receiving increased attention during the last years because of the lower spraying temperature required to deposit metallic coatings avoiding oxidation and reducing the coating porosity and the amount of residual stresses. The adhesion to the substrate and the growth mechanism of coldspray deposits are based on plastic deformation of impinging particles, so, in the case of high strength materials such as for example Ni alloys, it could be a lack in plastic deformation leading to insufficient compactness of the coating, barrier properties and high temperature resistance. Further improvements in the coatings performances could be attained by post-deposition thermal treatments to enhance coating adhesion and barrier properties. In this sense, the aim of this study is to explore a two-step way to produce high performances Inconel 625 alloy coatings by coldspray deposition followed by a laser glazing treatment. Coldspray Inconel 625 alloy coatings has been deposited onto AISI304 steel substrates. Laser glazing is performed using high power diode laser (HPDL) ROFIN-SINAR 13DS; the local thermal treatment on the coating surface induce microstructural changes which could modify and improve the coating compactness and performances. Coating morphology and microstructure has been evaluated and reported both before and after laser consolidation as a function of different laser conditions.
Laser Treatment of Thermal Sprayed NiCrBSi Coating: Modelling, Study and Characterization
Authors: Buza G. , Molnar A. , Felde I. , Balogh A. 
Published: November 2022

Abstract
Thermal sprayed NiCrBSi wear resistant coating is widely used in industry life increasing of worn parts for protective coating of the metallic surfaces. The coating is based on the mechanical anchoring of the splats onto the substrate surface and thermal integration among the splats in the coating is not possible during the spraying process due to the operation temperature, which is lower than the melting temperature of the coating material. This, in turn, results in the formation of non-homogeneous structures and voids in the coating. One of the techniques to avoid such situations is to integrate the splats through the controlled melting. This can be achieved through the laser melting process. In the present study, laser melting of thermal sprayed coating is modeled to determine the melt layer thickness. A lump parameter analysis is introduced in the model study and simulations are carried out in relation to the actual laser melting conditions. The melt layer predicted is compared with the experimental measurements. The micro structural analyses prior and post laser melting process are carried out using SEM and XRD, and the mechanical properties such as hardness, were also investigated. It is found that the predictions of the melt layer are in good agreement with experimental results.
Pt Thermal Sprayed Coating on Refractory-Bricks for Glass Melting
Authors: Ishikawa Y. , Hamashima K. 
Published: November 2022

Abstract
The dense refractory is applied for the high-temperature glass melting equipment. Furthermore, platinum or its alloy-clad refractory bricks are utilized to melt high quality glass in fields of optical and display glasses. From the viewpoint of the resource saving of rare metal, the decreasing of Pt-consumption is very serious problem for glass manufacturing. The platinum thermal spray coating is effective alternative technology to solve this problem for platinum cladding. A Pt-spray coated ceramics is difficult to get reliability due to the large difference of thermal expansion between the ceramic and the metal. In this study, we have investigated the bond strength of the platinum coat on the dense refractories which was textured by the mechanical process. As a result, the bond strength between the ceramic and the metal is 3-5 MPa. It is almost the same as the thermal spray ceramics coating on the metal. Furthermore, in case of the ceramics substrate that contains the glass phase, the bond strength between the ceramic and the metal increased to 14-17 MPa after 1773 K heat treatment.
Cold Spraying of Titanium using Enhanced Conditions and Optimized Nozzles
Authors: Binder K. , Gärtner F. , Klassen T. 
Published: November 2022

Abstract
In the past years a number of publications reported about Titanium coatings cold sprayed with a nominal power input between 17 to 47 KW (e. g Kinetiks 4000) reaching gas temperatures of maximum 850 °C and gas pressure of maximum 4 MPa. In a recent study at Helmut-Schmidt University (HSU), a Kinetiks 8000 prototype was used to spray titanium, employing a nominal power of about 92 KW to increase the gas temperature up to 1000°C at a pressure of 4 MPa. Under these parameters, a high tensile strength of over 480 MPa and a deposition efficiency (DE) close to 100% were achieved. The present study focuses on further enhanced gas and particle velocities by optimized nozzle designs. The increased particle velocities in comparison to that obtained by using commercial nozzles (types 24, 51) result in better coating performance and allow deviations from ideal (90°) impact angle without significantly reducing coating strength. The influences of process conditions are evaluated and discussed on the basis of coating strengths by Micro Flat Tensile and Tubular Coating Tensile tests, as well as electrical conductivities, nitrogen and oxygen contents.
The Effect of Fracture-Induced Ceramic Free Surfaces for Vacuum Kinetic Spray Bonding
Authors: Yong W. , Bae G. , Kang K. , Lee C. 
Published: November 2022

Abstract
The new kinetic spray coating technique, vacuum kinetic spray (aerosol deposition), utilizes the pressure gap between powder hopper and coating chamber which is vacuumed. In this study, to investigate the deposition mechanisms present in the vacuum kinetic spray coatings, α-Al2O3 and glass were chosen as the powder and substrate materials, respectively, and these were considered as the reference materials to examine the effect of free surfaces after particle fractures. Based on the finite-element modeling (using an AUTODYN-2D 12.1), single particle impacts were simulated, and the results elucidated the material shape, temperature variation and mass change of particle due to its fracture during impact. The plots of total mass change as a function of particle impact velocity demonstrate the deposition-optimized velocity zone (DOVZ) for successful deposition. Compared to as-received powders, from the transmission electron microscope (TEM) images, the defects such as dislocations of the ball-milled powders might increase the tendency of the powder particles to fracture upon impact. The cross-section images of the coating showed that the particle sizes of the coating were drastically decreased compared to those of initial powders. During coating, fractured particles enlarged the thermodynamically unstable free surface area and have a tendency of formation of bonding.
Applications of Cold Gas Spraying Compared to Manual Laser Welding in Connection with a Repair Contract in the Aerospace Field
Authors: Lutz P. 
Published: November 2022

Abstract
The attachment hooks of training missile wings are worn out. A technology must be found to repair the hooks. The hooks cannot be replaced. They are made of annealed steel of approx. 50 HRC hardness. A similar hardness should be achieved by the repair procedure without changing the basic material in its hardness and strength characteristics through heating. Additional annealing of the assembly is not possible due to its size. To find a solution to this problem, the cold gas spraying procedure was tested first. Cold gas spraying is a highly kinetic coating procedure in which powdery metal particles are strongly accelerated using inert gases at pressures of up to 40 bars and gas velocities far beyond 1000m/sec. When the particles hit the component surface, they form compact, strongly adherent layers of very low oxide content without preceding melting. As a second procedure, manual laser welding was tested using an Nd:YAG laser under a microscope with filling material. In this procedure, a weld pool can be generated within a few milliseconds. Due to the high velocity with which the energy is applied to the material and absorbed by it, a physical reaction is almost ruled out due to its thermal conductivity. Both procedures have the following advantages: function-related composition of the material applied is possible; the characteristics of the base material are not changed due to the low heating levels; and repeated treatment is possible. This paper compares the results of the procedures and discusses the limits of the technology for this specific application.
Development of Porous Ceramic Coating for High-Efficiency Cooling System
Authors: Arai M. , Suidzu T. 
Published: November 2022

Abstract
A transpiration cooling system for gas turbine applications has significant benefit for reducing the amount of cooling air and increasing cooling efficiency. In this paper, the porous ceramic coating using a plasma-spraying process, which can infiltrate a cooling gas and control the loss of coolant gas pressure, and the properties of the porous coating material fabricated in this study, such as permeability of the cooling gas, thermal conductivity and adhesion strength, are shown. The mixture of 8wt% yttria stabilized zirconia and polyester powders was employed as the coating, in order to deposit the porous ceramic coating onto the Ni-based super alloy substrate. The ceramic coating deposited with such mixed powder showed superior permeability for cooling gas and thereby to lead to considerable reduction of the substrate temperature based on the transpiration cooling mechanism. The adhesion strength of the porous ceramic coating was almost the same level as that of the ceramic coating utilized in current gas turbine components. The high-temperature exposure test revealed that the permeability of cooling gas did not change though a rigorous experience for a long period of up to 1000hours. It was also confirmed that the coating peeling damage did not occur after the thermal cycling test. It is concluded consequently that the transpiration cooling system proposed here for gas turbine could be achieved using the porous ceramic coating.
Deposition of Ceramic Oxides in Atmosphere and at Room Temperature Using the Powder Jet Deposition Technique
Authors: Ogawa K. , Arata H. , Takegoshi M. , Ono F. , Saito T. 
Published: November 2022

Abstract
Ceramic coating is a very important technique used to develop structures that resist wear, corrosion, or oxidation. In this study, the Powder Jet Deposition (PJD) technique is used to form ceramic coatings on structures. The PJD technique is similar to the cold spray technique, but it can be used to coat ceramic layers under room temperature and atmospheric conditions. Therefore, PJD was used for the creation and on-site repair of ceramic coatings on large, complicated structures. The aim of this study is to optimize the spray conditions for an aluminum titanate (TiAl2O5) coating on various substrates using the PJD technique and to evaluate the mechanism of ceramic deposition. In the case of the cold spray technique, a high particle velocity is essential to cause the large-scale plastic deformation of particles that is necessary for deposition. However, while using PJD on ceramic oxides, lower particle velocity proved to be a better deposition condition. The optimized spraying pressure, resulting in the thickest coating, was approximately 0.05 MPa. The particle velocity as measured using a high-speed camera was approximately 90m/s. Therefore with PJD, it is optimal to use a low velocity within a narrow range to form a ceramic coating.
Synthesis of Al2O3 Coatings by Plasma Transferred Arc
Authors: Drozda F. O. , Pianaro S. A. , d´Oliveira A. S. C. M. 
Published: November 2022

Abstract
The protection of metallic components against severe operating conditions has motivated the development of coatings for a wide range of applications. In particular, ceramic coatings can be used to protect components that operate under high temperatures and corrosive environments aiming to extend their service life. Several Thermal Spray processes can be used to process ceramic coatings on the metals, taking advantage of the mechanical bond typical of these processes. The exception is the Plasma Transferred Arc (PTA) process which results in a metallurgical bond between the coating and the substrate metal. This study analyzed the potential of PTA to process ceramic coatings on a steel substrate. Powder mixtures of aluminum (Al) and silicon oxide (SiO2) were deposited using three deposition currents aiming to synthetize alumina coatings “in situ” as the reaction between Silicon Oxide and Aluminum powders occurred. X-Ray diffraction, Scanning electron microscopy, Semi-quantitative chemical analysis by EDS and microhardness were used to analyze the processed surfaces. Coatings characterization confirmed that the synthesis of alumina occurred but it was not completed and a two layer coating was formed. A layer near the fusion line composed of Fe-Al matrix with Fe3Al precipitates and an external layer of Al, Si, and Al2O3. An increased in the iron content in the coating due to the higher interaction of the plasma arc with the substrate reduced the amount of Alumina formed.
Finite Element Simulation of Impacting Behavior of Particles in Cold Spraying by Eulerian Approach
Authors: Li W.-Y. , Yu M. , Liao H. L. 
Published: November 2022

Abstract
Numerical simulations focused on the impacting behavior of cold-sprayed particles are usually conducted with the Lagrangian method. However, the calculated output is much dependent on the mesh size due to the mesh distortion and/or the element-averaged variables in simulations. While the Eulerian method is attractive to overcome the mesh distortion. In this study, an investigation on the impacting behavior of cold-sprayed particles using the Eulerian formulation available in ABAQUS/Explicit was conducted with typical copper material. The results show that a jet can not be formed at the impacting velocities of 200-300m/s, but a continuous and smooth jet composed of the particle and substrate materials can be formed as the impacting velocity is in the extent of about 300-400 m/s which could be a theoretical value of the critical velocity for a successful bonding. At this velocity extent, the maximum PEEQ almost keeps unchanged accompanying with a temperature fluctuation. In addition, the jet presents discontinuous and the splashing causes the loss of material as the impacting velocity exceeds this velocity extent. Therefore, this model could be also used to predict the critical velocity of other materials besides the copper.
Influence of Gas Temperature, Particle Size and Substrate Material on the Deposition Behaviour of Cold Sprayed Magnesium Coatings
Authors: Suo X. K. , Guo X. P. , Li W. Y. , Planche M. P. , Bolot R. , Liao H. L. , Coddet C. 
Published: November 2022

Abstract
Magnesium coatings were deposited upon aluminum and stainless steel substrates by cold spraying. Three Mg powders with different particle size distributions were used as feedstock. The microstructures of as-sprayed coatings were evaluated by optical microscopy, and scanning electron microscopy. The coating observations show that a main gas temperature has an important effect on the deposition behaviour of particles. Changing the gas temperature from 350°C to 630°C involves an increase of the deposition efficiency from 1.57% to 19.57%. The effects of the particle size distribution and substrate material on the deposition efficiency of particles were also investigated. The results show that the particle size distribution has a significant effect on the deposition efficiency of particles which increases from 19.57% to 59% when the mean particle size decreases from 63 µm to 38 µm under gas temperature of 630°C. However, the deposition efficiency of particles was slightly influenced by the substrate material. In addition to these experimental results, the in-flight particle velocities were simulated by FLUENT software to point out the effects of the gas temperature and particle size distribution.
Influence of Annealing Treatment on the Microstructure and Microhardness of Cold Sprayed Nanostructured FeAl Coating
Authors: Wang H.-T. , Li C.-J. , Ji G.-C. , Yang G.-J. 
Published: November 2022

Abstract
In the present study, a nanostructured FeAl coating was prepared by cold spraying of ball milled powder. Annealing treatment was applied to the coating to investigate its effect on the phase structure, grain size and microhardness of the cold-sprayed nanostructured FeAl coating. The results showed that the FeAl phase was kept unchangeable when the coating annealed at the temperature above 500°C. Annealing temperature significantly influenced the microstructure and microhardness of cold-sprayed FeAl coating. With raising annealing temperature, the lamellar structure in the as-sprayed coating disappeared and a dense coating microstructure with fully bonding of deposited particles at their interfaces was achieved after annealing at 950°C. Nanograin growth of the FeAl phase occurred at an annealing temperature higher than 800°C. The microhardness of cold-sprayed FeAl coating remained about 400 Hv0.1 at the annealing temperature below 800°C and decreased to 300 Hv0.1 at 1100°C.
Study of the Influence of Particle Velocity on Adhesion Strength of Cold Spray Deposits
Authors: Huang R. , Fukanuma H. 
Published: November 2022

Abstract
The adhesion mechanism of deposits/substrate interface prepared by cold spray method has not been fully understood up to now. It seems that the adhesion strength is mainly determined by the mechanical (including the plastic deformation of particle and substrate) and thermal interaction between the particle and substrate when the particles impact onto the substrate with a high velocity. In order to understand the adhesion mechanism, the influences of particle impact velocity on the adhesion strength were investigated in this study. The particle velocity was obtained with DPV-2000 measurement and CFD simulation. The relationships between the adhesion strength of deposits/substrate interface and particle velocity were discussed. The results show that greater adhesion strength can be obtained with the increase of particle velocity. There are two available ways to improve the adhesion strength. One is to increase the temperature of working gas, and another is to employ helium gas as the working gas instead of nitrogen gas.