A critical review on the numerical simulation related to Physical Vapour Deposition

Physical Vapour Deposition (PVD) is a process usually used for the production of advanced coatings regarding its application in several industrial and current products, such as optical lens, moulds and dies, decorative parts or tools. This process has several variants due to its strong evolution along the last decades. The process is commonly assisted by plasma, creating a particular low pressure and medium temperature atmosphere, which is responsible for the transition of atomic particles between the target and the parts to be coated into a vacuum reactor. Several parameters are directly affecting the deposition, namely the substrate temperature, pressure inside the reactor, assisting gases used, type of current, power supply, bias, substrate and target materials, samples holder and corresponding rotation, deposition time, among others. Many mathematical models have been developed in order to allow the generation of numerical simulation applications, trying to combine parameters and expect the corresponding results. Numerical simulation applications were created around the mathematical models previously developed, which can play an important role in the prediction of the coating properties and structure. This paper intends to describe the numerical simulation evolution in the last years, namely the use of Finite Elements Method (FEM) and Computational Fluid Dynamics (CFD).info:eu-repo/semantics/publishedVersio

A critical review on the numerical simulation related to Physical Vapour Deposition

Physical Vapour Deposition (PVD) is a process usually used for the production of advanced coatings regarding its application in several industrial and current products, such as optical lens, moulds and dies, decorative parts or tools. This process has several variants due to its strong evolution along the last decades. The process is commonly assisted by plasma, creating a particular low pressure and medium temperature atmosphere, which is responsible for the transition of atomic particles between the target and the parts to be coated into a vacuum reactor. Several parameters are directly affecting the deposition, namely the substrate temperature, pressure inside the reactor, assisting gases used, type of current, power supply, bias, substrate and target materials, samples holder and corresponding rotation, deposition time, among others. Many mathematical models have been developed in order to allow the generation of numerical simulation applications, trying to combine parameters and expect the corresponding results. Numerical simulation applications were created around the mathematical models previously developed, which can play an important role in the prediction of the coating properties and structure. This paper intends to describe the numerical simulation evolution in the last years, namely the use of Finite Elements Method (FEM) and Computational Fluid Dynamics (CFD).LAETA/CETRIB/INEGI Research Center- FLAD – Fundação Luso-Americana para o Desenvolvimento | Ref. 116/2018Fundação para a Ciência e a Tecnologia | Ref. UID/EMS/0615/201

A Computational Approach for Modeling Plasma Sprayed Coatings from Splat to Bulk Deposits

In this study, a multi-pronged computational approach is developed to predict the effect of spray parameters on aluminum oxide splat formation and mechanical properties of the coatings. The splat morphology is investigated using computational fluid dynamics approach. Simulated splat morphologies show a good agreement with the experimentally obtained splats. Three-dimensional coating structure is constructed using the stochastic approach using simulated splat morphologies. Finite Element Analysis is used to compute the elastic modulus of the coating. An inter-splat correction factor is introduced which considers inter-splat cracks, interface bonding and other effects like curling of splats and splat sliding. After the correction factor, the computed elastic modulus for simulated coating is comparable to the experimental values (4~5%). This study shows that the proposed computational approach can predict the mechanical properties of the coating and is promising for developing plasma-sprayed coatings with predictable properties and can be extended to other materials systems

Application of thermal spray coatings in electrolysers for hydrogen production: advances, challenges, and opportunities.

Thermal spray coatings have the advantage of providing thick and functional coatings from a range of engineering materials. The associated coating processes provide good control of coating thickness, morphology, microstructure, pore size and porosity, and residual strain in the coatings through selection of suitable process parameters for any coating material of interest. This review consolidates scarce literature on thermally sprayed components which are critical and vital constituents (e.g. catalysts (anode/cathode), solid electrolyte, and transport layer, including corrosion-prone parts such as bipolar plates) of the water splitting electrolysis process for hydrogen production. The research shows that there is a gap in thermally sprayed feedstock material selection strategy as well as in addressing modelling needs that can be crucial to advancing applications exploiting their catalytic and corrosion-resistant properties to split water for hydrogen production. Due to readily scalable production enabled by thermal spray techniques, this manufacturing route bears potential to dominate the sustainable electrolyser technologies in the future. While the well-established thermal spray coating variants may have certain limitations in the manner they are currently practiced, deployment of both conventional and novel thermal spray approaches (suspension, solution, hybrid) is clearly promising for targeted development of electrolysers

Pulsed laser irradiation of plasma sprayed alumina-zirconia coatings

Plasma sprayed alumina and zirconia coatings are widely used coatings for many industrial applications. One of the most important applications is the production of thermal barrier coatings (TBCs). As sprayed alumina-zirconia coatings have relatively high degree of porosity and the properties of these coatings, such as high temperature, corrosion resistance, toughness and abrasion resistance may thereby be reduced. Laser surface treatment is one novel method that has potential for eliminating porosity and producing a homogeneous surface layer. In this research work the effect of excimer laser annealing on the surface of alumina-zirconia coatings was investigated. Alumina-40% zirconia (AZ-40) coatings were sprayed with a water-stabilized plasma spray gun. The coated surface was treated by excimer laser having a wavelength of 248 nm and pulse duration of 24 ns. In the first phase of the work an analytical model was developed in COMSOL Multiphysics 4.2 in order to investigate the effect of the defects on the heat distribution at the surface of samples irradiated by KrF beam. The model revealed that much higher temperatures were localized at areas having defects than at continuous surfaces. A detailed parametric study was carried out to investigate the effects of different laser surface treatment parameters including laser energy density (fluence), pulse repetition rate (PRR), and number of pulses on the microstructure, surface morphology, and mechanical properties of the coatings. The surface structure of the treated coating was examined by field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD). Treating the surface with low laser energy of 200mJ/cm2 etched a very thin layer from the coating, which helped revealing the microstructures initially present but hidden on the surface of as sprayed coatings. High laser energy of 800mJ/cm2 resulted in significant changes in the coat surface morphology where eutectic colonies growing in a pool of zirconia matrix were identified on the surface. The surface of untreated coating was continuously alternating up and down; it had a zigzag nature. After irradiating the surface with high laser fluence of 800mJ/cm2 the zigzag nature of roughness profile of untreated coating disappeared. Also irradiating the surface with high pulse repetition rate exhibited dome-like structures on the surface, which were associated with an increase in surface hardness

Recent progress in research on tungsten materials for nuclear fusion applications in Europe

The current magnetic confinement nuclear fusion power reactor concepts going beyond ITER are based on assumptions about the availability of materials with extreme mechanical, heat, and neutron load capacity. In Europe, the development of such structural and armour materials together with the necessary production, machining, and fabrication technologies is pursued within the EFDA long-term fusion materials programme. This paper reviews the progress of work within the programme in the area of tungsten and tungsten alloys. Results, conclusions, and future projections are summarized for each of the programme’s main subtopics, which are: (1) fabrication, (2) structural W materials, (3) W armour materials, and (4) materials science and modelling. It gives a detailed overview of the latest results on materials research, fabrication processes, joining options, high heat flux testing, plasticity studies, modelling, and validation experiments

Experimental and numerical analysis of fuel cells

Fuel Cells are attractive power source for use in electronic applications. Physical phenomena (water generation, saturation effect in fuel cell, poisoning, and thermal stress) are studied that governs the operation of a Proton Exchange Membrane Fuel Cell (PEMFC) and Solid Oxide Fuel cell (SOFC). Additionally, experimental studies and numerical simulations on PEMFC gas flow channel, the determination of the impact of the single channel fuel cell are presented. Furthermore, preliminary study is done for the application of APS (Air Plasma Spray) to SOFC and adhesion of anode and cathode with electrolytes for the determination of parameters involved in manufacturing the components of fuel cell. The new aspects on physical phenomena are significantly different from the currently popular relationships used in fuel cells as they are simplified from simulation and experimental results. In prior work, the physical phenomena such as water generation, saturation effect in fuel cell, poisoning, and thermal stress etc. are either assumed or used as adjustment parameters to simplify them or to achieve best fits with polarization data. In this work, physical phenomena are not assumed but determined via newly developed experimental and numerical techniques. The experimental fixtures and procedures were used to find better ways to control parameters of gas flow channel configurations for optimizing gas flow rates and performance, and gas flow channel pressure swing for CO poisoning recovery. The experimental results reveal controlling parameters for the mentioned cases and innovative design for Fuel cells. Numerical modeling were used to 2D and later 3D for simplification of single channel fuel cell model, transient localized heating to the catalyst layer for CO recovery, thermal stress that developed during SOFC fabrication by High Temperature vacuum Tube Furnace (HTVTF), and Gas Diffusion Layer and Gas Flow Channel (GDL-GFC) interfacial conditions with results based on commonly used relationships from the PEMFC literature. The modeling works reveal substantial impact on predicted GDL saturation, and consequently cause a significant impact on cell performance. Computational parametric relations and polarization curve results are compared to experimental polarization behavior which achieved a comparable relation

Tribological Behavior of Functional Surface: Models and Methods

Material loss due to wear and corrosion and high resistance to motion generate high costs. Therefore, minimizing friction and wear is a problem of great importance. This book is focused on the tribological behavior of functional surfaces. It contains information regarding the improvement of tribological properties of sliding elements via changes in surface topography. Tribological impacts of surface texturing depending on the creation of dimples on co-acting surfaces are also discussed. The effects of various coatings on the minimization of friction and wear and corrosion resistance are also studied. Friction can be also reduced by introducing a new oil