Download or read book Numerical Modeling of Suspension Plasma Spraying Process written by Elham Dalir and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Suspension plasma spraying (SPS), a relatively new deposition technique in thermal spray coating technology, has been increasingly applied to deposit high-quality thermal barrier coatings using sub-micron particles. An accurate simulation of the process includes developing a realistic plasma model both within and outside the torch. In the current work, a three-dimensional time-dependent model has been developed to simulate magneto-hydrodynamic fields inside a direct current (DC) plasma torch, including arc fluctuations. Reynolds stress model (RSM) is used to simulate the time-dependent turbulent plasma flow. A two-way coupled Eulerian-Lagrangian method is employed to investigate the effects of arc fluctuations on the droplets' trajectory, temperature, and speed. Sub-micron yttria-stabilized zirconia (YSZ) solid particles suspended into ethanol are modeled as multicomponent droplets. Kelvin-Helmholtz Rayleigh-Taylor (KHRT) breakup model is used to simulate the droplets' atomization. This model considers the effects of both aerodynamic forces (Wave model) and Rayleigh-Taylor instabilities on the atomization process combing a liquid core region (Levich model). Particles are also tracked after completion of suspension breakup and evaporation to obtain inflight particles' conditions (trajectory, size, speed, and temperature). The developed model is then employed to study the droplets' shape and solid concentration on the SPS process. A dynamic drag law is applied to analyze the effect of droplets/particles' shape on the SPS process. It was concluded that the percentage of molten particles in applying dynamic drag law (non-spherical particles) decreases significantly compared to using the spherical particles. The effect of suspension concentration is also studied. It was shown that using a higher solid concentration (20 compared to 10 wt.% YSZ) provides a denser coating as a result of the larger molten landed particles with higher velocities. Finally, the developed model is used to study the in-flight droplets/particles' atomization in the SPS process. Nine case studies are investigated to see the effect of KH, RT instabilities, and breakup length on the droplets/particles' atomization. A massive difference is represented in quantity, droplets' atomization pattern, and quality of the final landed particles over the substrate of some cases. The obtained size distributions of the trapped particles over the substrate are compared to the existing data to find the suggested ranges for the breakup model's constants.
Download or read book Modeling of Suspension Plasma Spraying written by Farzad Jabbari and published by . This book was released on 2014 with total page 105 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plasma Spraying is a coating process designed to deposit accelerated molten or semi-molten coating materials on prepared substrates. Suspension Plasma Spraying (SPS) is one type of Plasma Spraying with enhanced characteristics. Numerical modeling of this process helps us to find optimum operating parameters such as suspension injection position and standoff distance for substrates. A three-dimensional model of a plasma spraying system with radial suspension injection is studied in this work. To model turbulent flow of plasma, Reynolds Stress Model (RSM) is utilized. In addition, Lagrangian approach is used to track particles and two-way coupling is used to consider the effect of suspension on the gas flow. It should be mentioned that when mass flow rate of suspension is very high, the plasma plume cannot melt all particles that fly near the centerline. It is found that with optimum suspension mass flow rate, in general, almost all particles flying near the centerline are melted and reach high temperature. Furthermore, the effect of angle of suspension injection is studied. One can find that angles toward the gun give more penetration of suspension in the plasma plume, resulting in better melting and higher speed of particles. Finally, particle temperature, velocity and size distributions are studied at different standoff distances with respect to the plasma gun exit. It is shown that optimum standoff distance for the studied particles and plasma plume properties is between 3 to 6 cm. Less than 3 cm standoff distance, particles have no time to reach the melting point and the base liquid would not evaporate completely; and with more than 6 cm standoff distance, particles’ velocity will be significantly reduced. It should be mentioned that trajectory and penetration of suspension completely depends on velocity of suspension on one hand, and on the other hand temperature and velocity of the plasma plume. It is clear that for each condition, mass flow rate and velocity of plasma, the related modeling should be done to find velocity and temperature of particles.
Download or read book Handbook of Thermal Science and Engineering written by and published by Springer. This book was released on 2018-07-31 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Handbook provides researchers, faculty, design engineers in industrial R&D, and practicing engineers in the field concise treatments of advanced and more-recently established topics in thermal science and engineering, with an important emphasis on micro- and nanosystems, not covered in earlier references on applied thermal science, heat transfer or relevant aspects of mechanical/chemical engineering. Major sections address new developments in heat transfer, transport phenomena, single- and multiphase flows with energy transfer, thermal-bioengineering, thermal radiation, combined mode heat transfer, coupled heat and mass transfer, and energy systems. Energy transport at the macro-scale and micro/nano-scales is also included. The internationally recognized team of authors adopt a consistent and systematic approach and writing style, including ample cross reference among topics, offering readers a user-friendly knowledgebase greater than the sum of its parts, perfect for frequent consultation. The Handbook of Thermal Science and Engineering is ideal for academic and professional readers in the traditional and emerging areas of mechanical engineering, chemical engineering, aerospace engineering, bioengineering, electronics fabrication, energy, and manufacturing concerned with the influence thermal phenomena.
Download or read book Three Dimensional Simulation of Coating Build up In Suspension Plasma Spray Process written by Siavash Ghafouri Azar and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermal spray technology is widely used in many industries. The most important purposes of applying coatings are improving functional performance by the ability to work at higher temperature, increasing component life by protecting the surface against degradation, and repairing worn parts without changing the properties of the main part. Nano-structured coatings, which show improved characteristics as compared to conventional ones, have been extensively studied over the recent years. Suspension plasma spray (SPS) is a recently developed process that can produce nano-structured coatings on large surfaces. The technique involves spraying fine molten particles that solidify rapidly in contact with the substrate with grain size less than 100 nm. A suspension of sub-micron or nano-sized particles in a liquid carrier (water and ethanol) is injected in and atomized by the high speed high temperature plasma plume in a DC plasma spray torch. The SPS technique allows us to deposit micron-size particles more efficiently and creates fine grains, and small-sized pore microstructure. The microstructure of SPS coatings results from a series of complicated phenomena influenced by several parameters. Thus, depending on the suspension interaction with the plasma plume, powder types, solid concentration in suspension, substrate preparation method, plasma spray setup, spray distance, powder feed rate, etc. various microstructures can be obtained. Therefore, it is of great interest to predict the SPS coating microstructure within the context of particle conditions upon impact i.e. trajectory, size, and velocity. To understand how the microstructure of SPS coatings relates to particle conditions and predict coating attributes such as porosity, columnar structure, thickness and surface roughness, a three-dimensional predictive model for coating buildup on a substrate has been developed. In this model, the impact properties of each particle that comprise size, velocity, temperature, as well as particle's location near substrate are obtained from a computational fluid dynamics (CFD) model simulating the SPS process using a commercial Oerlikon Metco 3MB plasma torch. Subsequently, the trajectory of each particle close to the substrate surface is calculated to determine its final impact location on the substrate or previously deposited particles. It is assumed that particles stick at the impact location according to some prescribed scenarios. The coating structure is specified using a variable f(i,j,k) which is zero when the cell is empty and equals unity when the cell is filled with the spray material. The numerical results can capture the columnar structures observed in SPS coatings due to the shadow effect.
Download or read book Thermal Spray Fundamentals written by Pierre L. Fauchais and published by Springer Science & Business Media. This book was released on 2014-01-24 with total page 1587 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides readers with the fundamentals necessary for understanding thermal spray technology. Coverage includes in-depth discussions of various thermal spray processes, feedstock materials, particle-jet interactions, and associated yet very critical topics: diagnostics, current and emerging applications, surface science, and pre and post-treatment. This book will serve as an invaluable resource as a textbook for graduate courses in the field and as an exhaustive reference for professionals involved in thermal spray technology.
Download or read book Numerical Modeling of Suspension and Particle Transport in Thermal Spray Processes written by Mehdi Jadidi and published by . This book was released on 2017 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fine microstructured coatings have attracted many attentions in recent years due to various unique properties such as remarkable wear resistance, enhanced catalytic behavior, and superior thermal insulation. Suspension thermal sprays have been shown to be viable techniques in generating this kind of coatings. In these techniques, suspension which is a combination of a base liquid and fine solid particles is injected into a high-temperature high-velocity jets. After suspension breakup, the evaporation/combustion of base liquid becomes dominant. Then, the remained particles are accelerated and heated up by the gas flow and are deposited on a substrate which results in the generation of dense and well-adhered coatings. Suspension thermal spraying is very complex and many fields such as turbulent flow, multiphase flow, compressible flow, combustion, atomization, suspension properties, and plasma physics are involved in the mentioned technique. In addition, many parameters and mechanisms in this technique are still unknowns. Therefore, both numerical and experimental studies should be performed to obtain a comprehensive understanding of various phenomena in suspension thermal spraying and to improve the coating quality. The main goal of this study is the numerical modeling of suspension thermal sprays. An Eulerian-Lagrangian approach with two-way coupling assumption is presented and suspension droplet evolution in the atmospheric plasma spraying and high velocity oxygen fuel spraying techniques is investigated. In this model, suspension is considered as a multi-component mixture and a predefined droplet distribution is injected into the jet. In this approach, the breakup process is simulated using Taylor Analogy Breakup (TAB), and Kelvin-Helmholtz Rayleigh-Taylor (KHRT) breakup models. After breakup process is complete, the liquid component of suspension droplet evaporates/burns, and the particles/agglomerates are tracked in the domain. In general, the effects of suspension injection velocity, suspension properties, suspension injector location, standoff distance, substrate shape, and gas properties on the coating characteristics can be investigated by this approach. For example, in the case of radial injection of suspension into a plasma plume, it is illustrated that if particles move close to the jet centerline, particle velocity and temperature as well as probability of particle impact on the substrate will increase. The mentioned Eulerian-Lagrangian approach revealed that the breakup phenomenon mainly controls the droplets/particles trajectories, temperatures and velocities. However, the typical TAB and KHRT models ignore liquid/suspension column deformation, and need experimental calibration. To study the breakup process in more details, the effect of nonuniform gaseous crossflow and liquid column perturbations on the primary breakup of liquid jets are investigated. A coupled level set and volume-of-fluid method together with the large eddy simulation turbulence model are used to study the behavior of nonturbulent liquid jets in nonuniform crossflows. It is shown that liquid penetration height is significantly affected by the crossflow nonuniformity. In addition, to investigate the effects of liquid column perturbations on the breakup process, experimental studies are performed using shadowgraphy technique. General correlations for the penetration height, the column breakup point, and the onset of surface breakup are presented. It is found that the liquid column perturbations result in formation of large ligaments very close to the liquid and gas flows interaction point. These ligaments control the droplet size distribution and have significant effects on particle in-flight behavior, and coatings quality. The results of these studies can be used to estimate the spray trajectory in suspension plasma spray process, and to improve the accuracy of TAB and KHRT breakup models.
Download or read book Development of a Three Dimensional Suspension Plasma Spray Coating Build up Model written by Behrad Kashfi Ashtiani and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the last two decades, suspension plasma spray (SPS) coating methodology has drawn attention by showing a capacity to achieve a broad range of coating characteristics. Enormous efforts have been made to find the influential parameters on the SPS coating microstructure. However, due to the high computational costs and the complexity of the process, most of the studies have an experimental foundation. Regarding the high expenses of empirical investigations and time-consuming processes involved, such as setting up, sample preparation, etc., a simulation tool giving an approximation of the final coating properties is essential more than ever. A Simulation tool can provide also complementary information that help us better understand the coating microstructures obtained experimentally. This study aims to provide a tool to simulate SPS coatings build-up by applying both computational fluid dynamics (CFD), and an in-house developed model in MATLAB. The model can be used generally for SPS coating build-up simulations and is not limited to the studied problem. The framework was formed around a previously developed model with significant enhancements regarding the accuracy and computational cost. Two different approaches were followed in modeling particle deposition, considering the particle flattening process or deposition as a non-deformed particle. Results from both models offer promising trends capturing various coating microstructures already reported in the literature and predicting the effects of substrate geometry on the coating evolution. However, the porosity level and deposition rate are overestimated due to the assumptions made and the lack of data regarding the deposition efficiency based on the particle characteristics, respectively.
Download or read book Suspension Plasma Spray Coating of Advanced Ceramics written by Navid Hosseinabadi and published by CRC Press. This book was released on 2022-09-01 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: Suspension Plasma Spray Coating of Advanced Ceramics presents the significance of suspension plasma spray coating of ceramics for thermal barrier applications. It covers suspension formation and optimization in different oxide and non-oxide mixtures and ceramic matrix composites (CMC) of sub-micron and nanosized powders. Enabling readers to understand the importance of thermally inert and insulating ceramic coatings on metals and alloys, the book explains how to improve their utilization in applications, such as turbine blades or diesel engines, gas turbines, and coating methods. This book also discusses advanced topics on nanomaterials coatings in monolithic or composite forms as thermal barriers through organic and non-organic based suspensions using high energy plasma spray methods. Features: Presents significant thermal barrier properties using high energy plasma spray methods. Explores advanced surface modification techniques. Covers monolithic, composite, and solid solution ceramics coating. Discusses high precision coating methods. The book will be useful for professional engineers working in surface modification and researchers studying materials science and engineering, corrosion, and abrasion.
Download or read book Numerical Solution to Phase Change Problem written by Amirsaman Farrokhpanah and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A study of flight, impact, and solidification of molten ceramic droplets generated by suspension plasma spraying (SPS) is conducted. A three-dimensional model is developed for predicting behavior of droplets generated by SPS impacting a solid substrate. The model combines Smoothed Particle Hydrodynamics (SPH) integral interpolations with enthalpy formulations to capture the phase change process (solidification/melting). Surface tension is modeled as an internal force between all particles, that will be canceled in the bulk of fluid and generate unbalanced surface tension forces near the free surface. A Finite-Volume solver is also used to predict properties of the droplets at the time of reaching the substrate, i.e. temperature, velocity, and diameter. This solver uses discrete phase models to track flight, evaporation, and atomization of suspension droplets injected into plasma flow. Effects of high temperature gradients and non-continuum on solid particles in plasma flow are taken into account. Results are presented here in three steps. First, the newly developed numerical models for capturing solidification/melting in SPH are validated among various experimental, analytical, and numerical results from literature. These phase change models mainly fall into two main categories: (1) inclusion of latent heat as a source term in the enthalpy equation, (2) inclusion of latent heat by modifying the effective heat capacity in the enthalpy equation. Results confirm accuracy and robustness of the new methods. Secondly, results for droplet generation in SPS are presented. Effects of different parameters on droplets flight and impact are investigated. The goal here is to find suitable operating conditions for the plasma torch and injection process that guarantee impact of high quality droplets on the surface. Effects of injector parameters like injection location, flow rate, and angle along with effects of change in physical properties of droplets are studied. Finally, the newly improved SPH model is used to predict impact of molten ceramic droplets that are collected on the substrate. These cases include predictions for the spread factor and droplet behavior based on their impact velocity and temperature. Results are used to explain different scenarios happening in substrate coating using SPS.
Download or read book Three Dimensional Modeling of Arc Voltage Fluctuations in Suspension Plasma Spraying written by Elham Dalir and published by . This book was released on 2016 with total page 89 pages. Available in PDF, EPUB and Kindle. Book excerpt: Considering the wide range of plasma jet applications including plasma cutting, plasma spraying, and plasma arc waste disposal, realistic simulation of a plasma jet would significantly help to better understand and improve various processes. In this research, firstly a three-dimensional DC plasma torch is modeled using Joule effect method to simulate the plasma jet and its voltage fluctuations. The plasma gas is a mixture of argon/hydrogen and the arc voltage fluctuation is used as an input data in the model. Physical and chemical properties of plasma gases are used to model the plasma jet having high temperature and velocity. Reynolds Stress Model is used for time dependent simulation of the mixing flow of the plasma gas with atmosphere. After modeling the plasma jet, the results are applied to investigate the plasma oscillation effects on the trajectory, temperature, and velocity of suspension droplets. Suspensions are formed of ethanol and Yttria Stabilized Zirconia (YSZ, 8 wt.%) sub-micron particles and modeled as multicomponent droplets. To track the droplets and particles trajectory, a two-way coupled Eulerian-Lagrangian method is employed. In addition, in order to simulate the droplet breakup, Kelvin-Helmholtz Rayleigh-Taylor (KHRT) breakup model is used. After the completion of suspension breakup and evaporation, the spray particles are tracked through the domain to obtain the in-flight particle characteristics.
Download or read book Environmental Barrier Coatings written by Kang N. Lee and published by MDPI. This book was released on 2020-12-29 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: The global increase in air travel will require commercial vehicles to be more efficient than ever before. Advanced engine hot section materials are a key technology required to keep fuel consumption and emission to a minimum in next-generation gas turbines. Ceramic matrix composites (CMCs) are the most promising material to revolutionize gas turbine hot section materials technology because of their excellent high‐temperature properties. Rapid surface recession due to volatilization by water vapor is the Achilles heel of CMCs. Environmental barrier coatings (EBCs) is an enabling technology for CMCs, since it protects CMCs from water vapor. The first CMC component entered into service in 2016 in a commercial engine, and more CMC components are scheduled to follow within the next few years. One of the most difficult challenges to CMC components is EBC durability, because failure of EBC leads to a rapid reduction in CMC component life. Key contributors to EBC failure include recession, oxidation, degradation by calcium‐aluminum‐magnesium silicates (CMAS) deposits, thermal and thermo‐mechanical strains, particle erosion, and foreign object damage (FOD). Novel EBC chemistries, creative EBC designs, and robust processes are required to meet EBC durability challenges. Engine-relevant testing, characterization, and lifing methods need to be developed to improve EBC reliability. The aim of this Special Issue is to present recent advances in EBC technology to address these issues. In particular, topics of interest include but are not limited to the following: • Novel EBC chemistries and designs; • Processing including plasma spray, suspension plasma spray, solution precursor plasma spray, slurry process, PS-PVD, EB-PVD, and CVD; • Testing, characterization, and modeling; • Lifing.
Download or read book Handbook of Thermal Plasmas written by Maher I. Boulos and published by Springer Nature. This book was released on 2023-02-20 with total page 1973 pages. Available in PDF, EPUB and Kindle. Book excerpt: This authoritative reference presents a comprehensive review of the evolution of plasma science and technology fundamentals over the past five decades. One of this field’s principal challenges has been its multidisciplinary nature requiring coverage of fundamental plasma physics in plasma generation, transport phenomena under high-temperature conditions, involving momentum, heat and mass transfer, and high-temperature reaction kinetics, as well as fundamentals of material science under extreme conditions. The book is structured in five distinct parts, which are presented in a reader-friendly format allowing for detailed coverage of the science base and engineering aspects of the technology including plasma generation, mathematical modeling, diagnostics, and industrial applications of thermal plasma technology. This book is an essential resource for practicing engineers, research scientists, and graduate students working in the field.
Download or read book Plasma Spraying written by R. Suryanarayanan and published by World Scientific. This book was released on 1993 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt: The recent advances in plasma spraying are discussed in this book which divides into two sections — theory and application. The book presents sophisticated experimental techniques, diagnostics, theoretical models and computer simulations which not only improve the understanding and uses of the spraying process but also help to increase the reliability factor of the manufacturing components. Applications that are metallurgical, aeronautical, automobile, chemical, etc. are also shown. More importantly, applications that include silicon for solar cells, magnets and superconductors are also discussed for the first time. Advanced graduate students in materials science and engineering, research scientists, engineers and industries involved in plasma spray applications will benefit from this book.
Download or read book Drying of a Single Suspension Droplet in Suspension Plasma Spray written by Seyyed Morteza Javid and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Suspension plasma spray is a powerful coating technique for depositing high-quality thermal barrier coatings with promising mechanical and physical properties while taking advantage of the well-established atmospheric plasma spray process. In this process, fine ceramic particles are suspended in liquids such as water or ethanol before injection into a plasma jet. The heat from plasma evaporates the carrier liquid of injected suspension droplets and leads to an agglomeration of the particles. The agglomeration process plays a crucial role in the state of particles before impacting a substrate and, consequently, the mechanical properties of the coating. In this work, numerical models for simulating different cases of drying of a single suspension droplet in processes with a high evaporation rate like suspension plasma spray are devised. The models use a Lagrangian method for tracking suspended solid particles and the Eulerian method for the liquid phase. These models not only demonstrate droplet distortion during evaporation but also predict solid particles behavior suspended in the droplet. The numerical models can describe consecutive states of the agglomeration process, including droplet shrinkage, particle accumulation on droplet surface, and buckling. Also, the numerical analysis sheds more light on the complex phenomena of buckling, especially the interaction of the droplet interface and suspended solid particles, and different types of suspension droplet buckling. The numerical results reveal that the role of capillary forces in the shape of agglomerated particles is significant. It is found that particle-induced surface pressure drives the buckling of the suspension droplet. It is also shown that the particle-induced surface pressure reaches a threshold value at the onset of buckling and overcomes surface tension. Finally, the models have been validated by comparing the simulation results with designed experiments. The numerical results are in good agreement with the experimental ones, both qualitatively and quantitatively.
Download or read book Design of Thermal Barrier Coatings written by Mohit Gupta and published by Springer. This book was released on 2015-05-05 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book details the relationships between microstructure, interface roughness, and properties of thermal barrier coatings. The author proposes a method for the reduction of the thermal conductivity of the ceramic layer in order to increase the lifetime of thermal barrier coatings. He includes models for the optimization of ceramic layer microstructure and interface roughness.
Download or read book Plasma Nanoengineering and Nanofabrication written by Krasimir Vasilev and published by MDPI. This book was released on 2018-07-04 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a printed edition of the Special Issue "Plasma Nanoengineering and Nanofabrication" that was published in Nanomaterials
Download or read book Non equilibrium Modeling of Low pressure Plasma Spray Systems written by Chong Hyuck Chang and published by . This book was released on 1989 with total page 406 pages. Available in PDF, EPUB and Kindle. Book excerpt:
