bluuebunny/crossref_metadata_2025 huggingface dataset:
What Do You Need for a Good Training Program?
Authors: Puerta D. , Sauer J.P.
Published: September 2022

Finding the time, money, and resources to train both new and existing personnel is a constant challenge. Some studies have shown that training costs can be leveraged to show a three-to-one return by both identifying and preventing problems in manufacturing environments. Many quality specifications and systems require a documented training set-up and internal round robins (RR) to validate that the teaching has provided adequate instruction. There are many keys to a successful training program such as flexibility within the work schedule, the combination of both classroom and hands-on instruction, and discipline by both teachers/students to stay the course for completion of the course work. For many technical topics, training programs outside the company work environment are available. Many of the programs mirror the worldwide accepted non-destructive testing (NDT) type of training. There is some talk of certification for many types of training. However, in many cases, it is not difficult to set up a system given the guidelines/suggestions to formulate a program. Lessons learned and some sample program outlines will be presented and discussed.
Realization of an Internal Cold Spray Coating of Stainless Steel in an Aluminum Cylinder
Authors: Alexandre S. , Laguionie T. , Baccuad B.
Published: September 2022

This paper presents a development program carried out at the Commissariat à l’Energie Atomique (C.E.A.), whose objective was to successfully bond a dense coating of stainless steel on the internal surface of an aluminum cylinder with a diameter of 300 mm. To achieve these results, a specific nozzle was designed, with calculations and measurements of the particles velocity using DPV 2000. The influence of key parameters on the coating density was investigated. A prototype was successfully produced by optimizing process parameters.
Electrostatic Assist on a Cold Spray Process by Computational Simulation
Authors: Takana H. , Ogawa K. , Shoji T. , Nishiyama H.
Published: September 2022

The integrated model of thermofluid, splat formation and coating formation for a cold spray process has been established. The in-flight behavior of micro and submicron particles, the interaction between shock wave and particles in a supersonic jet impinging onto the substrate are clarified by this integrated model in detail. Then, the effect of electrostatic force on the particle acceleration is discussed in detail by carrying out a real-time computational simulation. It is shown that coating can be formed with the assist of electrostatic acceleration even though there is a lack of particle acceleration over critical velocity only through momentum transfer from airflow. Thus, the utilization of electrostatic acceleration enhances the performance of cold spray coating and contributes the extension of application range of a cold spray process.
Liquid Precursor Plasma Spraying: Modeling the Interactions between the Transient Plasma Jet and the Droplets
Authors: Marchand C. , Chazelas C. , Mariaux G. , Vardelle A.
Published: September 2022

Plasma spraying using liquid feedstock makes it possible to produce thin coatings (< 100 µm) with more refined microstructures than in conventional plasma spraying. However, the low density of the feedstock droplets makes them very sensitive to the instantaneous characteristics of the fluctuating plasma jet at the location where they are injected. In this study the interactions between the fluctuating plasma jet and droplets are explored by using numerical simulations. The computations are based on a three-dimensional and time-dependent model of the plasma jet that couples the dynamic behavior of the arc inside the torch and the plasma jet issuing from the plasma torch. The turbulence that develops in the jet flow issuing in air is modeled by a Large Eddy Simulation model that computes the largest structures of the flow which carry most of the energy and momentum.
Numerical Simulation of Droplet Impact on Patterned Surfaces
Authors: Parizi H.B. , Rosenzweig L. , Mostaghimi J. , Chandra S. , Coyle T. , Salimi H. , Pershin L. , McDonald A. , Moreau C.
Published: September 2022

In this work we present the numerical simulation results for the molten nickel and zirconia (YZS) droplets impact on different micro-scale patterned surfaces of silicon. The numerical simulation clearly showed the effect of surface roughness and the solidification on the shape of the final splat, as well as the pore creation beneath the material. The simulations were performed using a computational fluid dynamic software, Simulent Drop, The code uses a three-dimensional finite difference algorithm solving full Navier Stokes Equation with heat transfer and phase change. Volume of fluid (VOF) tracking algorithm is used to track the droplet free surface. Thermal contact resistance at the droplet– substrate interface is also included in the model. Specific attention is paid to the simulation of droplet impact under plasma spraying conditions. The droplet sizes ranged from 15 to 60 microns with the initial velocities of 70-250 m/s. The substrate surface was patterned by a regular array of cubes spaced at 1 µm and 5 µm from each other. The peak to valley height of each cube was between 1 to 3 µm. Different splat morphologies will be compared with those obtained from the experimental results under the same impact and surface conditions.
Thermal Spraying Technology and Its Applications in the Iron & Steel Industry in China
Authors: Hao R.L.
Published: September 2022

Through analyzing and predicting the development trend of tomorrow iron & steel industry in China and the effect of the improvement of the industry technology on the varying trend of the demand of steels, it appears that thermal spraying technology has a good chance for further developments. This paper presents the development of the thermal spray technology in Baosteel Company and its application in the iron & steel industry. It describes and analyzes the thermal spraying applications on mould narrow plates for CCL, CGL sink rolls, continuous annealing hearth rolls and cold mill processing rolls etc. It also introduced the work done by Baosteel Company on the development of thermal spray technology and the development of the softwares and experimental set-ups for the surface engineering lab. Various aspects such as corporation and “Both Payoff”, to the self-innovation in thermal spray technology, combination of the application technology with the manufacturing technology, pre-maintenance and complete life cycle service, etc, provide countermeasures on how to expand the application of thermal spraying technology in China iron & steel industry.
Thermoelectric Device Fabricated by Plasma Spray
Authors: Sodeoka S. , Suzuki M. , Inoue T. , Rückriem J.
Published: September 2022

A thermoelectric power generating device, in which all components were fabricated by plasma spray technique, was manufactured and its performance was evaluated. Its basic unit was composed of (Ca,Bi)3Co4O9 p-type semiconductor chip and (Sr,Y)TiO3-x n-type semiconductor chip. The plasma sprayed (Ca,Bi)3Co4O9 and (Sr,Y)TiO3-x deposits showed the Seebeck effect according to expectation. However, the ZT values, which indicated the thermoelectric performance, were still poor because of the low electric conductivity. Measurements of some basic properties revealed that increase of the target phase content was important for the p-type material. On the other hand, decrease of the resistivity was strongly desired for the n-type material by process improvement. Power generating test was performed using pipe shape device fully fabricated by plasma spraying and the electric output was successfully obtained under a temperature gradient.
Thermal Spray Technology Trends for Patent Applications in Japan
Authors: Tani K. , Namba Y. , Nakahira A.
Published: September 2022

Thermal spray technology trends in Japan were studied on the basis of patent information related to such technologies in Japan. Information related to research in and the basic development of thermal spray and allied coating technologies can be found in publication papers or documents submitted to national or international conferences, symposiums academic journals and so on. However, this kind of information does not always disclose key fundamentals pertinent to the industry in question. The present status of thermal spray technology and related future trends in Japan are described in this paper based on an investigating of patent filings, claims, and the specific industrial fields and applications related to such patent applicants.
Digital Fabrication of Functionally Graded PEN for SOFC by APS
Authors: Zhang H.O. , Yang Y.Z. , Wang G.L. , Sun D.W.
Published: September 2022

Atmosphere plasma spray and robot digital fabricating were integrated and presented to prepare the planar PEN and MOLB-type PEN SOFCs. On the basis of the spraying conditions optimized previously and the self-developed functionally graded powder feed system, two kinds of PEN cells were prepared. Then the microstructure and material components of the PEN cells were analyzed. The results show that graded layers were formed between the electrodes and electrolyte. Moreover, the material components and the porosity of the graded layers vary gradually. In particular, the porosities of the anode and cathode reach 32.74%, 32.24%, respectively. Using the AC complex impedance technology, the conductivity of the MOLB-type composite electrode is tested. As a comparison, the electrical conductivity of the MOLB-type composite electrode with the graded layers is larger than that without the graded layers.
Study of Aluminium Oxidation Induced by a Q-switched Nd:YAG Laser Treatment and Its Influence on the Adhesion Properties of a Plasma-Sprayed Alumina Coating
Authors: Barnier V. , Costil S. , Li H. , Coddet C. , Oltra R.
Published: September 2022

The aim of this work was to study the modifications induced by 10 ns single or cumulative pulses of a Q-switched Nd:YAG laser emitting in the near-infrared (λ = 1064 nm) on a pure aluminum surface with a laser energy density leading to a regime of interaction below the material ablation. The influence of these laser substrate pre-treatments on the mechanical behavior of an 83 µm thick alumina plasma sprayed coating was observed by evaluating the integrity of the coating/substrate interface with a "laser-ultrasonic method" thanks to a special set up using a probe laser interferometer. An increase in the alumina coating adhesion considering cumulative pulses for a laser energy density of 0.7 J/cm2 was observed above 100 laser pulses. The highest adhesion was obtained for a laser treatment considering 1000 shots. For a single pulse laser treatment, this increase was found applying an energy density of 1.8 J/cm2. These results were correlated with the observation of modifications on topography and morphology of the aluminum surface after laser irradiations using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results showed that the improvement of the adhesion of the plasma-sprayed alumina coatings was correlated to changes of the aluminum oxide morphology.
Microstructures and Compositions of Photocatalytic Plasma-Sprayed Titania-Hydroxyapatite Coatings
Authors: Ye F.-X. , Ohmori A. , Tsumura T. , Nakata K. , Li C.-J.
Published: September 2022

Hydroxyapatite (HAp Ca10(PO4)6(OH)2) is very known to be a biomaterial and an absorbent for chromatography. In this study, HAp was agglomerated with anatase TiO2 to manufacture thermal spray powders to improve the absorption activity of TiO2 and then improve its photocatalytic activity. The microstructures and compositions of plasma sprayed TiO2, TiO2-10%HAp, TiO2-30%HAp and HAp coatings were investigated. Due to the low thermal conductivity of HAp compound, not all HAp particles fully melted even under the arc current of 800 A. Low temperature stable β-Ca3(PO4)2 was detected in the sprayed HAp coatings. The addition of HAp inhibited the phase transformation of anatase TiO2 to rutile. Under the arc current of 600 A, the anatase content in the TiO2, TiO2-10%HAp and TiO2-30%HAp coatings was 10.6%, 20% and 42%, respectively. Although slightly decomposition of HAp to α-Ca3(PO4)2 was found in the TiO2-30%HAp coatings, it did not decompose to CaO and P2O5 according to the XRD and EDAX analysis. With the increasing of the spraying distance from 70 mm to 110 mm, the anatase content in the TiO2-30%HAp coatings decreased from 34% to 17% under arc current of 700 A. The addition of the secondary gas of helium has no significant influence on the melting state of the TiO2-HAp feedstock powders.
Apatite Formation on Vacuum Plasma Sprayed Titanium Coating after Chemical Modification
Authors: Chen Y.K. , Ji H. , Zheng X.B.
Published: September 2022

Formation of bonelike apatite is an essential prerequisite for implants to make direct bond to living bone. The apatite formation can be assessed in vitro using a simulated body fluid (SBF) that has almost equal compositions of inorganic ions to human blood plasma. In this study, Ti coatings were prepared by vacuum plasma spraying, and then they were treated by NaOH aqueous solution, immersed in distilled water, heated at 600 °C in a furnace. Microstructure and bioactivity of the surface modified Ti coatings were examined by SEM observation and SBF test respectively. The results obtained revealed that a net-like structure comprising of many micropores was present on the surfaces of the treated Ti coatings. After immersed in SBF, apatite layer was formed on their surfaces, suggesting that the surface modification coatings have good bioactivity.
Bioactivity of Plasma Sprayed Calcium Silicate/ZrO2 Composite Coatings
Authors: Liu X. , Xie Y. , Ding C.
Published: September 2022

In this work, 30wt% calcium silicate, including wollastonite and dicalcium silicate, were mixed with 70wt% ZrO2, respectively. The composite powders were deposited onto Ti-6Al-4V substrates to prepare wollastonite/ZrO2 and dicalcium silicate/ZrO2 composite coatings using plasma spraying technology. The bioactivity of coatings was evaluated using simulated body fluid soaking test. After the composite coatings were soaked in simulated body fluid for a certain period, apatite was formed on the surface of the wollastonite/ZrO2 and dicalcium silicate/ZrO2 composite coatings. In addition, the ZrO2 in composite coatings may protect the calcium silicate in the coatings from dissolving in simulated body fluid.
Effect of Heat Treatment on Pore Architecture and Associated Property Changes in Plasma Sprayed TBCs
Authors: Paul S. , Golosnoy I.O. , Cipitria A. , Clyne T.W. , Xie L. , Dorfman M.R.
Published: September 2022

Plasma sprayed Thermal Barrier Coatings (TBCs) exhibit many interlamellar pores, voids and microcracks. These microstructural features are primarily responsible for the low global stiffnesses and the low thermal conductivities commonly exhibited by such coatings. The pore architecture thus has an important influence on such thermophysical properties. In the present work, the effect of heat treatment (at temperatures up to 1400°C, for times of up to 10 hours) on the pore architecture in detached YSZ top coats has been characterised by Mercury Intrusion Porosimetry (MIP) and gas-sorption techniques. While the overall porosity level remained relatively unaffected (at around 10-12%) after the heat treatments concerned, there were substantial changes in the pore size distribution and the (inter-connected) specific surface area. Fine pores (<~50 nm) rapidly disappeared, while the specific surface area dropped dramatically, particularly at high treatment temperatures (~1400°C). These changes are thought to be associated with intra-splat microcrack healing, improved inter-splat bonding and increased contact area, leading to disappearance of much of the fine porosity. These microstructural changes are reflected in sharply increased stiffness and thermal conductivity. Measured thermal conductivity data are compared with predictions from a recently-developed analytical model, using the deduced inter-splat contact area results as input parameters. Good agreement is obtained, suggesting that the model captures the main geometrical effects and the pore size distribution measurements reflect the most significant microstructural changes.
Preliminary Study of Oxidation Behavior of Cold Sprayed Nanostructured NiCrAlY Bond Coatings
Authors: Zhang Q. , Li C.-J. , Li C.-X. , Yang G.-J. , Wang X.-R. , Wang H.-T. , Lui S.-C.
Published: September 2022

Nanostructured NiCrAlY coating was deposited by cold spray, using a milled powder for applications as a bond coat to thermal barrier coating. A shot-peening treatment was then applied to the as-sprayed coating to modify the coating surface morphology. The oxidation behavior of the coating with the shot-peened surface was investigated under isothermal oxidation at 900°C and 1,000°C for different times. The oxidation behavior of the coating was characterized through surface morphology and cross-sectional microstructure by scanning electron microscopy and X-ray diffraction analysis. It was found that a uniform oxide layer was formed on the surface of the shot-peened nanostructured NiCrAlY coating during oxidation at temperatures of 900°C and 1,000°C. The nanostructure of the initial coating possibly promoted rapid formation of α-Al2O3 oxide. It was clearly revealed that the surface morphology of the coating significantly impacted the morphology of the oxide. The surface geometry of the cold-sprayed MCrAlY coating must be modified to promote formation of a protective oxide film during oxidation, through application of a post-treatment process such as shot-peening.
Study of Microstructure, Vickers Microindentation and Microhardness Distribution of HVOF Sprayed Composite MoB/CoCr Coating
Authors: Lv H.P. , Wang J. , Zhai C.S. , Li F. , Sun B.D.
Published: September 2022

Thermal spray coatings of new MoB/CoCr cermets were developed. The mechanical behavior of HVOF-sprayed MoB/CoCr novel composite coatings was evaluated via Vickers microhardness. Microstructure of the coatings on 316L stainless steel substrates, as well as powders, were studied with optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD). X-ray microanalysis of the coatings was carried out using energy dispersive X-ray spectrometer (EDS) attached to the SEM. The distributions of microhardness values of the coatings were analyzed via Weibull statistic. Weibull analysis revealed a bimodal distribution of Vickers microhardness values. Such distribution was attributed to the presence of melted and unmelted phases in the resultant coating produced from the microstructured powder feedstock. The excellent mechanical properties of the coating are due to the MoB/CoCr powder, which results in the formation of complex ternary transition metal boride hard particles that exhibit exceptional mechanical properties.
On the Role of Spraying Process on Microstructural, Mechanical and Thermal Response of Alumina Coatings
Authors: Costil S. , Verdy C. , Bolot R. , Coddet C.
Published: September 2022

Thermal spraying is a widely used technology in a range of industrial applications to provide coatings improving the surface characteristics. According to the thermal and kinetic specificities of processes (APS, VPS, flame, electric arc), any kind of material can be sprayed. Among materials, ceramic coatings present several interesting aspects for wear resistance, corrosion protection as well as for thermal or electrical insulation; particularly alumina coatings which appear as the most commonly used. Many techniques can be used to spray such kind of materials. From all of them, atmospheric plasma spraying (APS) is a rather well-established process but some other processes can also be used with a lower economical impact as the flame technology. The aim of this study was to analyse the alumina coating properties according to the technology employed such as atmospheric plasma spraying or wire flame spraying using the Rokide and the Master Jet guns. After usual micrographic analyses by SEM, physical and mechanical properties were measured considering the thermal conductivity and the hardness.
Oxidation and Hot Corrosion Resistance of HVOF Wc-NiCrFeSiB Coating on Ni- and Fe-based Superalloys at 800 °C
Authors: Sidhu T.S. , Malik A. , Prakash S. , Agrawal R.D.
Published: September 2022

The present work evaluates the oxidation and hot corrosion resistance of high velocity oxy-fuel (HVOF) sprayed WC-NiCrFeSiB coating deposited on Ni-based superalloy (Superni 75) and Fe-based superalloy (Superfer 800H). The coated as well as uncoated specimens were exposed to air and molten salt (Na2SO4-25%NaCl) environment at 800 °C under cyclic conditions. The thermogravimetric technique was used to establish the kinetics of corrosion. The corrosion products were characterized using the combined techniques of X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron probe micro analyser (EPMA). The WC-NiCrFeSiB coating provides necessary resistance against oxidation and hot corrosion to both the nickel and iron based superalloys in the given environmental conditions at 800 °C. The oxides of active elements of the coatings, formed in the surface scale as well as at the boundaries of nickel and tungsten rich splats, have contributed for the oxidation and hot corrosion resistance of WC-NiCrFeSiB coatings, as these oxides act as barriers for the diffusion/penetration of the corrosive species through the coatings.
Study on Corrosion Resistance Properties of Al-based Coating Prepared by Arc Spraying
Authors: Ren C.L. , Wei Q. , Fang J.Y. , Li Z.X. , Zhou X.J.
Published: September 2022

Al-based coating was prepared with Al-based cored wire by arc spraying. The properties of high-temperature oxidation resistance and corrosion resistance of Al-based coating were compared with those of Fe-Al coating and 45CT coating. The property of H2S corrosion resistance of Al-based coating was compared with that of A304 stainless steel and Fe-Al coating. The results suggest that the Al-based coating has better properties of high-temperature oxidation resistance and corrosion resistance than Fe-Al coating and 45CT coating. Al-based coating has better property of H2S corrosion resistance than A304 stainless steel and Fe-Al coating.
Corrosion Study of Cold Sprayed Aluminum Coatings onto Al 7075 Alloy
Authors: Irissou E. , Arsenault B.
Published: September 2022

Aluminum coatings were deposited onto Al7075 T651 structural alloy using both cold spraying and arc spraying. Arc spray coatings were produced using optimized parameters for two atomizing gases, namely air and nitrogen. Cold spray coatings were produced using a low pressure system with air and nitrogen as propelling gases. Six surface preparation procedures prior to deposition were evaluated. Interface quality of as-deposited coatings was investigated by means of fluorescent dye interface penetration technique, bond strength testing and backscattered electron microscopy. Environmentally assisted cracking tests were performed to study the corrosion protection capability of the resulting coatings for structural applications. Micrographs of samples taken before and after cyclic load testing in salt water immersion were compared. The results demonstrated that the Al coatings produced by both arc spray and cold spray provide to Al7075 alloy a cathodic protection against cracking and localized corrosion. However, to obtain such coating properties arc spray technique required advanced surface preparation prior to deposition. For cold spray, the surface preparation has minimal influence on the coating properties thus making this process more advantageous than arc spraying for this application.
The Oxy-Fuel Ionisation (OFI) Spray Processes
Authors: Barykin G. , Parco M.
Published: September 2022

Owing to gas velocities in the super-sonic regimen in combination with moderate flame temperatures, the HVOF processes are preferred for the deposition of wear and/or corrosion resistant carbides as well as Hastelloy, Triaballoy and Inconel alloys. The resulting coatings have usually very high bond strengths, fine as-sprayed surface finishes and low oxide levels. However, the generation of a supersonic flow of combustion products supposes the implementation of relatively high gas flow rates and high energetic gas mixtures, which are intrinsically associated with high production costs, limiting the application of this technology in some industrial fields. This work summarises the first results in the development of a prototype aimed to show the potential of a new thermal spray technology named Oxy-Fuel Ionisation spraying for the development of high quality carbide base coatings. The OFI process is a supersonic combustion process as well, enhanced by the addition of ionised gas specimens. The arising combustion process is characterised by its stability within a broader range of the “fuel/oxidant” correlation in comparison to conventional HVOF systems, because of the presence of ionised gas specimens which are acting as a catalyst. It has been proved that this developed prototype allows the thermal spray deposition of carbide based materials with relatively low oxygen flow rates. For comparison two different coating materials were investigated, WC-17Co and Cr3C2-NiCr. The process parameters were optimised in terms of the micro hardness, the porosity and the decarburization of the resulting coatings.
Development of Nanostructured Thermal Barrier Coatings
Authors: Jiang X.L. , Liu C.B. , Lin F.
Published: September 2022

In this paper, nanostructured 5-8wt.% yttria stabilized zirconia (5-8YSZ) thermal barrier coating (TBC) deposited by air plasma spraying (APS) of powder and new TBC with novel structure deposited by solution precursor plasma spray (SPPS) are compared. Plasma spray conditions, coating forming mechanisms, microstructures, phase compositions, thermal conductivities, and thermal cycling lives of the APS nanostructured TBC and the SPPS nanostructured TBC are discussed. The SPPS process is different from either physical/chemical vapor deposition process or conventional plasma spray deposition in the aspects of substrate temperature, coating forming mechanism, growth rate, and coating structure.
Rapid and Continuous Deposition of Porous Nanocrystalline SnO2 Coating with Interpenetrating Pores for Gas Sensor Applications
Authors: Chien K. , Coyle T.
Published: September 2022

In this paper we proposed a rapid and continuous process for the production of nanoporous coatings for functional applications. Experiments following two statistical designs were implemented to screen and investigate the spraying parameters’ effects on coating crystallinity and porosity to gain a better understanding. The spraying stand-off distance, solution flow rate and arc current were identified as having significant effects on coating porosity and crystallinity. The investigation yielded a microstructure comprised of interpenetrating pores and layered structures with embedded nanopores. A deposition mechanism was postulated to explain this peculiar microstructure. Gas sensors constructed from the coatings had ethanol sensitivities at room temperature comparable to those reported in the literature for conventional thick-film coatings and a maximum sensitivity near 200°C.
Triplex Pro 200 – Potential and Advanced Applications
Authors: Bobzin K. , Ernst F. , Zwick J. , Richardt K. , Sporer D. , Molz R.J.
Published: September 2022

Process optimization and innovative material applications gain more and more interest under the aspect of continuously increasing functional and structural demands on thermal sprayed coatings. With the cascaded triple arc plasma gun generation, the atmospheric plasma spraying process was advanced by delivering enhanced plasma stability and, associated with this, higher deposition efficiency. The TriplexPro 200 is the latest version of a three cathode plasma spraying system on the market and offers distinctly higher particle velocities, due to its advanced nozzle design. As a result of the higher particle velocities, lower particle oxidation and higher coating density can be realized. In order to increase the corrosion protection of metallic coatings and the thermal properties of TBCs, the aim of the work performed is a parametric study to deposit advanced coating systems for high temperature applications.
Fragmentation and Splashing of Plasma-Sprayed Nickel on Oxidized Metals
Authors: McDonald A. , Chandra S. , Lamontagne M. , Moreau C.
Published: September 2022

Plasma-sprayed, molten nickel particles (60 µm diameter) were photographed during impact on oxidized 304L stainless steel surfaces that were maintained at room temperature or at 350oC. The steel samples were oxidized at different temperatures. Droplets approaching the surface were sensed using a photo detector and after a known delay, a fast charge-coupled device (CCD) camera was triggered to capture time-integrated images of the spreading splat from the substrate front surface. A two-color pyrometer was used to collect the thermal radiation from the particles to follow the evolution of their temperature after impact. Molten nickel particles impacting on oxidized steel at room temperature fragmented significantly, while heating the surfaces produced splats with disk-like morphologies. Impact on steel that was highly oxidized induced the formation of finger-like splash projections at the splat periphery. The splat cooling rate and thermal contact resistance between the splat and non-heated oxidized steel varied significantly as the degree of oxidation increased; heating the oxidized steel greatly reduced the variations. It was suggested that the large variations in splat cooling rates and thermal contact resistances on the non-heated oxidized steel was due primarily to the presence of adsorbates on the steel surface.
Synthesis of Lanthanum Silicates with Apatite-type Structure by Atmospheric Plasma Spraying
Authors: Gao W. , Zhang C. , Lapostolle F. , Liao H. , Coddet C. , Ji V.
Published: September 2022

The emergence of lanthanum silicate as an electrolyte is required to accelerate the development of synthesis techniques for intermediate temperature solid oxide fuel cells (ITSOFCs). Apatite-type oxide powders of La10(SiO4)6O3 have been elaborated through atmospheric plasma spraying (APS) using micro-scale mixtures of La2O3 and SiO2 powders. Granulometer and scanning electron microscopy analyses have indicated the result of high temperature reaction and rapid solidification in the evolution of multi-scale microstructure.
Comparison of the Microstructures and Tribological Behavior of Blended and Nanostructured Composite Coatings by APS
Authors: Cho J.H. , Xiong Y.M. , Kumar S. , Ji Y.G. , Lee C. , Hwang S.Y.
Published: September 2022

A group of blended and spray dried solid lubricants with the same nominal composition were deposited by atmospheric plasma spraying (APS). The wear resistance of two coatings formed at room temperature and 350°C was evaluated using a rig test to simulate actual application conditions. The results showed that the blended powder coating showed inferior mechanical and tribological properties due to its non-uniform microstructure, which were induced by the differences in the physical and thermophysical properties of each constituent phase. However, the nanostructured spray-dried feedstock coating showed a better wear resistance due to its lower porosity, higher hardness and higher bond strength. In addition, the friction coefficient decreased with an increase of the Ag fraction and the uniformity of the Ag solid lubricant in the coating.
Optimization of Sensor Optics for Industrial Thermal Spray Sensors
Authors: Blain J. , Pouliot L. , Nadeau F. , Lamontagne M. , Moreau C.
Published: September 2022

For a decade now, industrial sensors have been commercially available to both academia and industry. In general, these sensors measure individual and/or bulk properties of the powders being sprayed. Experience has shown that normally, researchers will tend to favor sensors with high spatial resolution like the DPV 2000, because of the fundamental information they give about the plume structure. Such information is vital for proper gun design and spray parameter optimization. However, for process monitoring applications typically performed with a sensor like the AccuraSpray, it is often more convenient to measure global properties over a wider volume inside the plume. In this case, there is always a tradeoff to be made between spatial resolution and fundamental process understanding. This paper illustrates this point by comparing two optical configurations, one with high spatial resolution and another one with medium resolution. This latter configuration makes use of a cylindrical lens to expand the sensor field of view in a direction perpendicular to the spray direction. Results clearly show that with minor optical modifications such sensors can be tailored to precise industrial requirements.
Change in Graphite Carbon Structure of Cast Iron Coatings through Different Spray Flame Situations
Authors: Tsunekawa Y. , Ueno T. , Kozaki T. , Okumiya M. , Ozdemir I.
Published: September 2022

Graphitization behavior of water-atomized cast iron powder at each thermal spraying step, such as droplet flight, droplet impingement and splat layering, was successively examined. Both as-atomized cast iron powder and coatings sprayed with the powder contain no graphite structure owing to their rapid solidification. A short period of pre-annealing at 1173 K allows the formation of graphite structure in the cast iron powder, in which there exist precipitated graphite of 3.58 mass%. The microstructure observation exhibits that pre-existed pores in the as-atomized powder strongly affect the precipitating sites of graphite, that is, mainly inside the individual powder instead of the surface. However, marked reduction in graphite structure occurs to coatings sprayed with the pre-annealed powder because of in-flight burning and dissolution into molten iron. In-process post-annealing at 773 K for 60 s reveals the formation of graphite structure resulted from the decomposition of iron based metastable carbide in splats and coatings sprayed with the as-atomized powder. Chemical analysis demonstrates that graphitization level of post-annealed cast iron coatings is higher than that of coatings sprayed with the pre-annealed powder. Precipitated intersplat graphite structure of 1.68 mass% appears in cast iron coatings when introducing methane as a powder feeding carrier gas which is liable to decompose in plasma flame. The resultant coatings with graphite structure embedded in hard matrix are anticipated to offer superior wear resistance in comparison to centrifugally cast iron containing flaky graphite of 1.76 mass%.
Increase of Process Robustness through Offline Process Control and Noise Factor Influence Reduction
Authors: Bobzin K. , Ernst F. , Zwick J. , Richardt K. , Schmitt R. , Doeren J.
Published: September 2022

After having established an offline process control based on the optical process diagnostic system PFI (Particle Flux Imaging) the process robustness has been increased by experimental identification of the impact of the noise factors „electrode wear“ and „injector wear“ in the APS process. Neural networks were used for implementing a process controller into a GTV APS process control center. In combination with the PFI system a tool was installed in the process center that is able to predict coating quality by analyzing some characteristics of the plasma and the particle plume. The neural network can be trained for all applications and all feedstock materials. An offline controller is instructing the operator through a desktop in order to train the network. The training, that means the monitoring of the process through different parameter setups and its reactions, is generated and executed automatically. Due to the fact that controlling the process parameters cannot influence every aspect of the coating quality, noise factors have to be regarded. For the APS process the electrode wear and the injector wear were identified as the most influencing noise factors. Both were analyzed by means of Design of Experiment (DOE) and long-term monitoring (200 hrs). The samples were characterized by light microscopy and different coating test methods that were chosen with respect to the coatings functions (e.g. wear resistance). The result of this work is a set of parameters that are as robust against both noise factors as possible and that are adapted to certain changes by a neural network process control.
Excellence in Robot Programming for Coating Applications
Authors: Moody D.R.
Published: September 2022

Impressive gains have been made in thermal spray coatings through material development and coating parameter selection. However, it is usually up to shop personnel to develop a robot program to achieve the final coating. Coating programs are often developed using trial and error. Some motion and deposit analysis programs are available. However, they can be costly and require a level of expertise that is generally not available to the typical coating shop. This paper discusses how Microsoft Excel 2003 software can be used as an aid for off-line development of a robot program for coating applications. It starts with a discussion of the Normal Distribution characteristic of thermal spray patterns. It then goes through development of an example using standard Excel function and chart tools for interactive feedback of the coating layers. Also included is a discussion on the use of the program for sensitivity analysis regarding changes to the spray pattern.
A Novel Intelligent Adaptive Temperature Control Approach of Sprayed Coating for APS Process
Authors: Xia W.S. , Zhang H.O. , Wang G.L.
Published: September 2022

Coating damages, such as cracks and spallation, always occur under high temperature gradient and its resulting residual stress level. This is why it is important and necessary to monitor and control the coating temperature during atmospheric plasma spray process. In this paper, a novel measurement approach for substrate and coating temperatures is presented. It is based on IR pyrometery combined to specific robot scanning trajectories in order to avoid harsh environment of spray workshops. The temperature-time evolution was continually detected and recorded during preheating, spraying and cooling stages and the two specific factors, periodic average temperature and standard deviation were adopted to evaluate the temperature variation and the fluctuation of the thermal cycle relevant to one robot scanning cycle based on the statistical method. These two factors were successful in describing the temperature variation during experimental processing sets. Finally, on the basis of experimental results of the influence of Z typed robot spray trajectory parameters, including spray distance, spray velocity and scanning step on coating temperature characterized by the two factors, an intelligent adaptive control of sprayed coating temperature was developed to obtain constant temperature cycles by means of adjusting robot trajectories, cooling, among other considered operating parameters. Excellent control performance is observed.
High Temperature Mechanical Properties of Plasma Sprayed Thin YSZ Deposits
Authors: Syed A.A. , Antou G. , Denoirjean A.
Published: September 2022

Elastic properties of 20 and 40 µm thick deposits of yttria fully stabilized zirconia (YSZ), fabricated by vacuum plasma spraying (VPS) and air plasma spraying (APS) with modified injection system were investigated at room temperature by nanoindentation, and 4 point flexion test and at 800°C by 4 point bend test. The data was correlated with structural analysis of different YSZ deposits. At room temperature, E values of VPS YSZ deposit decreased from 237 ± 6 to 105 ± 5 GPa on increasing nanoindentation load from 1 mN to 450 mN. The results indicated change from intrinsic to defect-dependent E values with increasing load. Despite lower porosity of VPS deposit (6 ± 1%) compared to that of APS (24 ± 1%), E values, measured by flexion test at room temperature and at 800°C, of former were 35 ± 1 and 16 ± 1 and of latter were 55 ± 1 and 18 ± 1 GPa respectively. The interlamellar sliding, parallel to applied load, was considered as prime reason of lower rigidity of deposits.
Effects of Substrate Temperature During Thermal Spray Deposition on Mechanical Properties of Ceramic Coating
Authors: Yamano H. , Takabatake T. , Tani K.
Published: September 2022

Mechanical properties of thermal-sprayed ceramic coatings were investigated. Al2O3 and Y2O3-stabilized ZrO2 (YSZ) coatings were deposited on plate substrates. Stainless steel plates and aluminum plates, of different thermal expansion coefficients, were used as substrates. The coatings were prepared at two different thicknesses. During deposition of each sample, the history of substrate temperature was recorded. Four-point bending tests were carried out, while strains at the coating surface and the substrate surface were measured with strain gages. The apparent Young's modulus of the coating was determined using the composite beam theory. In addition, the rupture strain of the coating was measured by three-point bending test. The relationship between the results of these tests and the temperature of each substrate during deposition is discussed.
Microstructure Control of Thermally Sprayed Co-based Self-fluxing Alloy Coatings by Diffusion Treatment
Authors: Sakata K. , Nakano K. , Miyahara H. , Matsubara Y. , Ogi K.
Published: September 2022

This paper describes microstructure control aimed for wear-resistance improvement of Co-based (Co-Cr-W-B-Si) self-fluxing alloy coating by diffusion treatment. The diffusion treatments of thermally sprayed Co-based self-fluxing alloy coating on steel substrate were carried out at 1370K to 1450K for 600s to 6000s under an Ar gas atmosphere. Microstructural variations of the coating and the interface between the substrate and the coating were investigated in detail. A proper diffusion treatment precipitates two kinds of fine compounds in Co-based matrix. XRD and EPMA analysis revealed these precipitates to be a chromium boride dissolving cobalt and a wolfram boride containing cobalt and chromium. The size of each precipitate became larger with increasing treatment temperature and time. A coating with the proper size borides showed a superior wear-resistance.
Plasma Electrolytic Oxidation of Arc Sprayed Aluminium Coatings
Authors: Pokhmurskii V. , Nykyforchyn G. , Student M. , Klapkiv M. , Karpenko G.V. , Pokhmurska H. , Wielage B. , Grund T. , Wank A.
Published: September 2022

Different post treatment methods such as heat treatment, mechanical processing, sealing, etc. are known to be capable to improve microstructure and exploitation properties of thermal spray coatings. In this work a plasma electrolytic oxidation of aluminium coatings obtained by arc spraying on aluminium and carbon steel substrates is carried out. Microstructure and properties of oxidised layers formed on sprayed coating as well as on bulk material are investigated. Oxidation is performed in electrolyte containing KOH and liquid glass under different process parameters. It is shown that thick uniform oxidised layers can be formed on arc sprayed aluminium coatings as well as on solid material. Distribution of alloying elements and phase composition of obtained layers are investigated. A significant improvement of wear resistance of treated layers in two types of abrasive wear conditions is observed.
Modeling and Experimental Study of the High Pressure Gas Atomization of Liquid Metals
Authors: Allimant A. , Planche M.-P. , Dembinski L. , Coddet C.
Published: September 2022

Liquid metal atomization using a De Laval nozzle has proven its efficiency in producing fine and narrow sized powder. The modeling work of gas dynamics related to nozzle geometry has led to a better understanding of the effects of the processing parameters. During the emptying of the crucible, the decrease in the static height of the melt acts on the metal mass flow rate. An experimental study on the particle size distribution in the cross-section of the spray and its evolution during the process has confirmed the unsteadiness of the process. By establishing a model to fit the gas pressure to the mass flow rate evolution, an almost steady state can be reached for the process. This has brought us to reduce the mean particle size and to improve the narrowness of the as-atomized particle size distribution.
Effect of Laser Irradiation on Micro Structure of Carbide Coatings
Authors: Kuwashima T. , Saitoh T. , Sonoda T. , Suzuki K. , Fujiwara M.
Published: September 2022

In the thermal spraying technique, the process includes some problems such as insufficient cohesive strength between particles in the coating. It is considered that the laser treatment of thermal spray coating will be effective method to improve the coating properties. In this study, an yttrium aluminum garnet (YAG) laser treatment was carried out on the sprayed coating in order to examine the effect of laser beam on the coating properties and post laser treatment method and hybrid spraying method were carried out. Irradiation laser power conditions were 1.5kW, 2.0kW and 2.5kW, and defocus distance conditions were ±0mm, +30mm, +60mm, +90mm, changing the energy density and the traverse speed conditions were 100mm/s, 200mm/s, 300mm/s. In post treatment method the affected region in the Cr3C2-Ni-Cr coating is smaller with increasing traverse speed. Laser energy density affected the microstructure. In the case of defocus distance ±0mm and traverse speed is 100mmm/s there are three different regions, melted region, heat affected region and no affected region in the coating. The micro Vickers hardness of melted region of coatings was lower and heat affected region of coatings was higher than no laser treatment coating. It was considered that with post laser treatment method it was very difficult to treat the coating uniformly. In the blast erosion test, the wear-out rate of hybrid spray coating was lower than that of the HVOF spray coating. It is considered that the improvement of micro Vickers hardness of Cr3C2-Ni-Cr hybrid sprayed coating resulted from the precipitation of fine chrome carbide in the matrix and their strengthening affect cohesive strength between lamella in the coating. In WC-Co hybrid sprayed coating, the improvement of micro Vickers hardness resulted from the porosity decrease. The coating structure was different even in the identical processing condition by the place. The micro Vickers hardness of melted area of coatings was lower and heat affected area of coatings was higher than no laser treatment coating.
Phase Assemblage of Al-Cu-Cr Quasicrystalline Coatings Sprayed by Low Power Plasma
Authors: Fu Y.Q. , Zhou F. , Gao Y.
Published: September 2022

Al-Cu-Cr quasicrystalline (QC) coatings were deposited onto mild steel Q235A substrate by low power plasma spraying. The plasma torch was designed such that the powders can be injected axially (parallel to the axis of the plasma arc) into the region between the anode and cathode, and the carrier gases were transferred to the plasma flame, so the heating efficiency of the powders is greatly increased and the velocity of particles is much higher than an externally-fed powder system. The Al-Cu-Cr QC coatings were sprayed via this new technique at different plasma power (3~7kW) by controlling the secondary plasma gases (H2 and N2) flow or changing the arc current. The results show that, the original powder was mainly composed of a dominant icosahedral quasicrystalline phase I-Al65Cu24Cr11 and a minor monoclinic θ-Al13Cr2. However, besides these two phases, body-centered cubic α- Al69Cu18Cr13, the approximant to quasicrystal I-Al65Cu24Cr11, has been detected in as-sprayed coatings. On the other hand, peak intensity of QC phase I-Al65Cu24Cr11 decreased and that of crystalline phases (θ-Al13Cr2 or α-Al69Cu18Cr13) increased as the plasma power was increased.