Understanding plasma spraying
TL;DR: In this paper, a summary of the actual knowledge in plasma spraying with an emphasis on the points where work is still in progress is presented, including: the plasma torches with the resulting plasma jets and their interactions with the surrounding environment, powder injection with the heat, momentum and mass transfers between particles and first plasma jets, the particles flattening and solidification, forming splats which then layer to form the coating.
Abstract: This article intends to summarize our actual knowledge in plasma spraying with an emphasis on the points where work is still in progress. It presents successively: the plasma torches with the resulting plasma jets and their interactions with the surrounding environment; the powder injection with the heat, momentum and mass transfers between particles and first plasma jets and then plasma plume; the particles flattening and solidification, forming splats which then layer to form the coating; the latest developments related to the production of plasma sprayed finely structured coatings.
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TL;DR: In this paper, a review summarises the research work carried out in the field of carbon nanotube (CNT) metal matrix composites (MMCs), focusing on the critical issues of CNT-reinforced MMCs that include processing techniques, nanotubes dispersion, interface, strengthening mechanisms and mechanical properties.
Abstract: This review summarises the research work carried out in the field of carbon nanotube (CNT) metal matrix composites (MMCs). Much research has been undertaken in utilising CNTs as reinforcement for composite material. However, CNT-reinforced MMCs have received the least attention. These composites are being projected for use in structural applications for their high specific strength as well as functional materials for their exciting thermal and electrical characteristics. The present review focuses on the critical issues of CNT-reinforced MMCs that include processing techniques, nanotube dispersion, interface, strengthening mechanisms and mechanical properties. Processing techniques used for synthesis of the composites have been critically reviewed with an objective to achieve homogeneous distribution of carbon nanotubes in the matrix. The mechanical property improvements achieved by addition of CNTs in various metal matrix systems are summarised. The factors determining strengthening achieved by CNT reinforcement are elucidated as are the structural and chemical stability of CNTs in different metal matrixes and the importance of the CNT/metal interface has been reviewed. The importance of CNT dispersion and its quantification is highlighted. Carbon nanotube reinforced MMCs as functional materials are summarised. Future work that needs attention is addressed.
1,265 citations
Tohoku University1, Nagoya University2, Applied Materials3, Kyoto University4, Eindhoven University of Technology5, University of Manchester6, Commonwealth Scientific and Industrial Research Organisation7, Chevron Corporation8, University of Minnesota9, University of Toulouse10, General Electric11, University of Michigan12, Ruhr University Bochum13, Open University14
TL;DR: The 2012 plasma road map as mentioned in this paper provides guidance to the field by reviewing the major challenges of low-temperature plasma physics and their many sub-fields, as well as a review of the current state of the art in the field.
Abstract: Low-temperature plasma physics and technology are diverse and interdisciplinary fields. The plasma parameters can span many orders of magnitude and applications are found in quite different areas of daily life and industrial production. As a consequence, the trends in research, science and technology are difficult to follow and it is not easy to identify the major challenges of the field and their many sub-fields. Even for experts the road to the future is sometimes lost in the mist. Journal of Physics D: Applied Physics is addressing this need for clarity and thus providing guidance to the field by this special Review article, The 2012 Plasma Roadmap.
571 citations
Cites background from "Understanding plasma spraying"
...• In plasma spraying, arc instabilities, which involve the interaction of the arc with the anode, continue to be a subject of research [83]....
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TL;DR: The use of graphene as reinforcement for structural materials is motivated by their exceptional mechanical/functional properties and their unique physical/chemical characteristics as discussed by the authors. But this review focuses on MMCs and CMCs because of their technological importance for structural applications and the unique challenges associated with developing high-temperature composites with nanoparticle reinforcements.
Abstract: This review critically examines the current state of graphene reinforced metal (GNP-MMC) and ceramic matrix composites (GNP-CMC) The use of graphene as reinforcement for structural materials is motivated by their exceptional mechanical/functional properties and their unique physical/chemical characteristics This review focuses on MMCs and CMCs because of their technological importance for structural applications and the unique challenges associated with developing high-temperature composites with nanoparticle reinforcements The review discusses processing techniques, effects of graphene on the mechanical behaviour of GNP-MMCs and GNP-CMCs, including early studies on the tribological performance of graphene-reinforced composites, where graphene has shown signs of serving as a protective and lubricious phase Additionally, the unique functional properties endowed by graphene to GNP-MMCs and GNP-CMCs, such as enhanced thermal/electrical conductivity, improved oxidation resistance, and excellent bi
456 citations
Cites background from "Understanding plasma spraying"
...injected directly into the formed plasma or downstream depending on the degree of heat transferred desired [71,72]....
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TL;DR: In this paper, a double approach to thermal plasmas is presented, which combines the scientific procedure with an engineering point of view, and the model is useful in each case for studying important phenomena or processes in greater detail.
Abstract: Electrical arcs and, more generally thermal plasmas, are widely used in many applications and the understanding or the improvement of the corresponding processes or systems, often requires precise modelling of the plasma. We present, here, a double approach to thermal plasma modelling, which combines the scientific procedure with an engineering point of view. First, we present the fundamental properties of thermal plasmas that are required in the models, followed by the basic equations and structures of the models. The third part is devoted to test cases, and its objectives are the study of some basic phenomena to show their influence on arc behaviour in simple configurations, and the validation of the models: we point out the roles of radiation, thermal conductivity and electrical conductivity for a stationary or transient wall-stabilized arc and we validate a three-dimensional model for a free-burning arc.Sections 4–6 deal with several industrial configurations and the model is useful in each case for studying important phenomena or processes in greater detail. For transferred arcs, such as those used in metallurgy, the energy transfer from the arc to the anode, and the presence of metallic vapour and pumping gas are essential. For a non-transferred plasma torch used for plasma spraying, we illustrate the relevance of a three-dimensional model and we present the interaction of the plasma with powders. Problems related to high- and low-voltage circuit-breakers are then presented, and various typical mechanisms are modelled. Finally, several non-equilibrium models useful for quasi-thermal conditions are presented in detail, showing how they take into account the chemical kinetics and two-temperature plasmas occurring under particular conditions, such as decaying arcs or inductively coupled plasmas.
310 citations
TL;DR: In this article, a review of the latest achievements in the field of plasma-assisted fabrication of biocompatible CaP-based coatings for medical implants with the emphasis on the coatings composition, structure, mechanical and biological performance is presented.
Abstract: The review is focused on the latest achievements in the field of plasma-assisted fabrication of biocompatible CaP-based coatings for medical implants with the emphasis on the coatings composition, structure, mechanical and biological performance. The discussed properties of biocompatible CaP coatings have been recently prepared using the most frequently applied plasma-assisted techniques such as plasma spraying (PS), radio-frequency (RF) magnetron sputtering, pulsed laser deposition (PLD), and ion beam-assisted deposition (IBAD). The review shows that plasma-assisted fabrication allows us to prepare dense, homogeneous, pore-free and high adherent biocompatible coatings able to prevent the leaching of toxic ions from metal to the surrounding tissues or rough and porous coatings capable of stimulating osteogenesis of a new bone. The main advantages and limitations of the described techniques of CaP-based coatings fabrication are presented as well as the most important challenges and critical issues are highlighted.
305 citations
References
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Book•
14 Feb 1995
TL;DR: In this article, the authors present a detailed overview of the main steps in the process of spraying particles and their properties, including properties such as temperature, surface properties, and surface properties.
Abstract: Preface to the Second Edition. Preface to the First Edition. Acronyms, Abbreviations and Symbols. 1 Materials Used for Spraying. 1.1 Methods of Powders Production. 1.1.1 Atomization. 1.1.2 Sintering or Fusion. 1.1.3 Spray Drying (Agglomeration). 1.1.4 Cladding. 1.1.5 Mechanical Alloying (Mechanofusion). 1.1.6 Self-propagating High-temperature Synthesis (SHS). 1.1.7 Other Methods. 1.2 Methods of Powders Characterization. 1.2.1 Grain Size. 1.2.2 Chemical and Phase Composition. 1.2.3 Internal and External Morphology. 1.2.4 High-temperature Behaviour. 1.2.5 Apparent Density and Flowability. 1.3 Feeding, Transport and Injection of Powders. 1.3.1 Powder Feeders. 1.3.2 Transport of Powders. 1.3.3 Injection of Powders. References. 2 Pre-Spray Treatment. 2.1 Introduction. 2.2 Surface Cleaning. 2.3 Substrate Shaping. 2.4 Surface Activation. 2.5 Masking. References. 3 Thermal Spraying Techniques. 3.1 Introduction. 3.2 Flame Spraying (FS). 3.2.1 History. 3.2.2 Principles. 3.2.3 Process Parameters. 3.2.4 Coating Properties. 3.3 Atmospheric Plasma Spraying (APS). 3.3.1 History. 3.3.2 Principles. 3.3.3 Process Parameters. 3.3.4 Coating Properties. 3.4 Arc Spraying (AS). 3.4.1 Principles. 3.4.2 Process Parameters. 3.4.3 Coating Properties. 3.5 Detonation-Gun Spraying (D-GUN). 3.5.1 History. 3.5.2 Principles. 3.5.3 Process Parameters. 3.5.4 Coating Properties. 3.6 High-Velocity Oxy-Fuel (HVOF) Spraying. 3.6.1 History. 3.6.2 Principles. 3.6.3 Process Parameters. 3.6.4 Coating Properties. 3.7 Vacuum Plasma Spraying (VPS). 3.7.1 History. 3.7.2 Principles. 3.7.3 Process Parameters. 3.7.4 Coating Properties. 3.8 Controlled-Atmosphere Plasma Spraying (CAPS). 3.8.1 History. 3.8.2 Principles. 3.8.3 Process Parameters. 3.8.4 Coating Properties. 3.9 Cold-Gas Spraying Method (CGSM). 3.9.1 History. 3.9.2 Principles. 3.9.3 Process Parameters. 3.9.4 Coating Properties. 3.10 New Developments in Thermal Spray Techniques. References. 4 Post-Spray Treatment. 4.1 Heat Treatment. 4.1.1 Electromagnetic Treatment. 4.1.2 Furnace Treatment. 4.1.3 Hot Isostatic Pressing (HIP). 4.1.4 Combustion Flame Re-melting. 4.2 Impregnation. 4.2.1 Inorganic Sealants. 4.2.2 Organic Sealants. 4.3 Finishing. 4.3.1 Grinding. 4.3.2 Polishing and Lapping. References. 5 Physics and Chemistry of Thermal Spraying. 5.1 Jets and Flames. 5.1.1 Properties of Jets and Flames. 5.2 Momentum Transfer between Jets or Flames and Sprayed Particles. 5.2.1 Theoretical Description. 5.2.2 Experimental Determination of Sprayed Particles' Velocities. 5.2.3 Examples of Experimental Determination of Particles Velocities. 5.3 Heat Transfer between Jets or Flames and Sprayed Particles. 5.3.1 Theoretical Description. 5.3.2 Methods of Particles' Temperature Measurements. 5.4 Chemical Modification at Flight of Sprayed Particles. References. 6 Coating Build-Up. 6.1 Impact of Particles. 6.1.1 Particle Deformation. 6.1.2 Particle Temperature at Impact. 6.1.3 Nucleation, Solidification and Crystal Growth. 6.1.4 Mechanisms of Adhesion. 6.2 Coating Growth. 6.2.1 Mechanism of Coating Growth. 6.2.2 Temperature of Coatings at Spraying. 6.2.3 Generation of Thermal Stresses at Spraying. 6.2.4 Coatings Surfaces. 6.3 Microstructure of the Coatings. 6.3.1 Crystal Phase Composition. 6.3.2 Coatings' Inhomogeneity. 6.3.3 Final Microstructure of Sprayed Coatings. 6.4 Thermally Sprayed Composites. 6.4.1 Classification of Sprayed Composites. 6.4.2 Composite Coating Manufacturing. References. 7 Methods of Coatings' Characterization. 7.1 Methods of Microstructure Characterization. 7.1.1 Methods of Chemical Analysis. 7.1.2 Crystallographic Analyses. 7.1.3 Microstructure Analyses. 7.1.4 Other Applied Methods. 7.2 Mechanical Properties of Coatings. 7.2.1 Adhesion Determination. 7.2.2 Hardness and Microhardness. 7.2.3 Elastic Moduli, Strength and Ductility. 7.2.4 Properties Related to Mechanics of Coating Fracture. 7.2.5 Friction and Wear. 7.2.6 Residual Stresses. 7.3 Physical Properties of Coatings. 7.3.1 Thickness, Porosity and Density. 7.3.2 Thermophysical Properties. 7.3.3 Thermal Shock Resistance. 7.4 Electrical Properties of Coatings. 7.4.1 Electrical Conductivity. 7.4.2 Properties of Dielectrics. 7.4.3 Electron Emission from Surfaces. 7.5 Magnetic Properties of Coatings. 7.6 Chemical Properties of Coatings. 7.6.1 Aqueous Corrosion. 7.6.2 Hot-gas Corrosion. 7.7 Characterization of Coatings' Quality. 7.7.1 Acoustical Methods. 7.7.2 Thermal Methods. References. 8 Properties of Coatings. 8.1 Design of Experiments. 8.2 Mechanical Properties. 8.2.1 Hardness and Microhardness. 8.2.2 Tensile Adhesion Strength. 8.2.3 Elastic Moduli, Strengths and Fracture Toughness. 8.2.4 Friction and Wear. 8.3 Thermophysical Properties. 8.3.1 Thermal Conductivity and Diffusivity. 8.3.2 Specific Heat. 8.3.3 Thermal Expansion. 8.3.4 Emissivity. 8.3.5 Thermal Shock Resistance. 8.4 Electric Properties. 8.4.1 Properties of Conductors. 8.4.2 Properties of Resistors. 8.4.3 Properties of Dielectrics. 8.4.4 Electric Field Emitters. 8.4.5 Properties of Superconductors. 8.5 Magnetic Properties. 8.5.1 Soft Magnets. 8.5.2 Hard Magnets. 8.6 Optical Properties. 8.6.1 Decorative Coatings. 8.6.2 Optically Functional Coatings. 8.7 Corrosion Resistance. 8.7.1 Aqueous Corrosion. 8.7.2 Hot-medium Corrosion. References. 9 Applications of Coatings. 9.1 Aeronautical and Space Industries. 9.1.1 Aero-engines. 9.1.2 Landing-gear Components. 9.1.3 Rocket Thrust-chamber Liners. 9.2 Agroalimentary Industry. 9.3 Automobile Industry. 9.4 Ceramics Industry. 9.4.1 Free-standing Samples. 9.4.2 Brick-Clay Extruders. 9.4.3 Crucibles to Melt Oxide Ceramics. 9.4.4 Ceramic Membranes. 9.5 Chemical Industry. 9.5.1 Photocatalytic Surfaces. 9.5.2 Tools in Petrol Search Installations. 9.5.3 Vessels in Chemical Refineries. 9.5.4 Gas-well Tubing. 9.5.5 Polymeric Coatings on Pipeline Components. 9.5.6 Ozonizer Tubes. 9.6 Civil Engineering. 9.7 Decorative Coatings. 9.8 Electronics Industry. 9.8.1 Heaters. 9.8.2 Sources for Sputtering. 9.8.3 Substrates for Hybrid Microelectronics. 9.8.4 Capacitor Electrodes. 9.8.5 Conductor Paths for Hybrid Electronics. 9.8.6 Microwave Integrated Circuits. 9.9 Energy Generation and Transport. 9.9.1 Solid-oxide Fuel Cell (SOFCs). 9.9.2 Thermopile Devices for Thermoelectric Generators. 9.9.3 Boilers in Power-generation Plants. 9.9.4 Stationary Gas Turbines. 9.9.5 Hydropower Stations. 9.9.6 MHD Generators. 9.10 Iron and Steel Industries. 9.10.1 Continuous Annealing Line (CAL). 9.10.2 Continuous Galvanizing Section. 9.10.3 Stave Cooling Pipes. 9.11 Machine Building Industry. 9.12 Medicine. 9.13 Mining Industry. 9.14 Non-ferrous Metal Industry. 9.14.1 Hot-extrusion Dies. 9.14.2 Protective Coatings against Liquid Copper. 9.14.3 Protective Coatings against Liquid Zirconium. 9.15 Nuclear Industry. 9.15.1 Components of Tokamak Device. 9.15.2 Magnetic-fusion Energy Device. 9.16 Paper Industry. 9.16.1 Dryers. 9.16.2 Gloss Calender Rolls. 9.16.3 Tubing in Boilers. 9.17 Printing and Packaging Industries. 9.17.1 Corona Rolls. 9.17.2 Anilox Rolls. 9.18 Shipbuiding and Naval Industries. 9.18.1 Marine Gas-turbine Engines. 9.18.2 Steam Valve Stems. 9.18.3 Non-skid Helicopter Flight Deck. References. Index.
1,688 citations
TL;DR: In this paper, the main experimental techniques for measurement of residual stresse are briefly described, with particular attention given to the method of continuous curvature monitoring, and relationships are presented between residual stresses and corresponding strain energy release rates during interfacial debonding.
Abstract: An overview is presented of the development of residual stresses in thermal spray coatings and their ef-fects on interfacial debonding. The main experimental techniques for measurement of residual stresse are briefly described, with particular attention given to the method of continuous curvature monitoring. Boundary conditions satisfied by all residual stress distributions are identified and expressions derived for the curvatures and stress distributions arising from a uniform misfit strain between coating and sub-strate.It is noted that stress distributions in thick coatings rarely correspond to the imposition of such a uniform misfit strain, so that recourse to numerical methods becomes essential for quantitative predic-tion of stress distributions. Relationships are presented between residual stresses and corresponding strain energy release rates during interfacial debonding. The effect on this of superimposing stresses from an externally applied load is outlined. The initiation of debonding is then considered, covering edge effects and other geometrical considerations. Finally, some specific case histories are briefly outlined to illustrate how the various theoretical concepts involved relate to industrial practice.
445 citations
TL;DR: In this article, the impact and flattening of single particles on smooth or rough substrates with different tilting is summarized and different diagnostic methods, including imaging, are briefly described.
Abstract: This paper summarizes our knowledge at the beginning of 2003 about splat formation. First, the analytical and numerical models related to the impact and flattening of single particles on smooth or rough substrates with different tilting are recalled. Then, the different diagnostic methods, including imaging, are briefly described. The last part of the paper is devoted to the results and their discussion. Studies are related to the effect of various parameters on particle flattening. They include the characteristics of particles prior to impact: normal impact velocity, temperature, molten state, oxidation state, etc.; the parameters related to the substrate: tilting angle, roughness, oxide layer composition, thickness and crystallinity, desorption of adsorbates and condensates, wetting properties between impacting particle and substrate, etc.; and, finally, the parameters related to the heat exchange between the flattening particle and the substrate. They depend on previous parameters and control the propagation of the solidification front within the flattening particle, eventually modifying its liquid flow. It is obvious from this review that, if our understanding of the involved phenomena has been drastically improved during the last years, many points have still to be clarified. This is of primary importance because all the coating properties are linked to the particle flattening, splat formation, and layering.
428 citations
TL;DR: A review of the present status of the research and technological development in the field of superhard nanocomposite coatings is attempted in this article, where a number of deposition techniques have been used to prepare Nanocomposites. Among them, reactive magnetron sputtering is most commonly used.
Abstract: In this paper, a review of the present status of the research and technological development in the field of superhard nanocomposite coatings is attempted. Various deposition techniques have been used to prepare nanocomposite coatings. Among them, reactive magnetron sputtering is most commonly used. Nanocomposite coating design methodology and synthesis are described with emphasis on the magnetron sputtering deposition technique. Also discussed are the hardness and fracture toughness measurements of the coatings and the size effect. Superhard nanocomposite thin films are obtainable through optimal design of microstructure. So far, much attention is paid to increasing hardness, but not enough to toughness. The development of next generation superhard coatings should base on appropriate material design to achieve high hardness and at the same time high toughness.
425 citations
TL;DR: In this article, a three-dimensional model of droplet impact onto asymmetric surface geometries is developed, based on RIPPLE, and combines a fixed-grid control volume discretization of the flow equations with a volume tracking algorithm to track the droplet free surface.
Abstract: A three-dimensional model has been developed of droplet impact onto asymmetric surface geometries. The model is based on RIPPLE, and combines a fixed-grid control volume discretization of the flow equations with a volume tracking algorithm to track the droplet free surface. Surface tension is modeled as a volume force acting on fluid near the free surface. Contact angles are applied as a boundary condition at the contact line. The results of two scenarios are presented, of the oblique impact of a 2 mm water droplet at 1 m/sec onto a 45° incline, and of a similar impact of a droplet onto a sharp edge. Photographs are presented of such impacts, against which the numerical results are compared. The contact angle boundary condition is applied in one of two ways. For the impact onto an incline, the temporal variation of contact angles at the leading and trailing edges of the droplet was measured from photographs. This data is applied as a boundary condition to the simulation, and an interpolation scheme propos...
422 citations