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Anne Neville - One of the best experts on this subject based on the ideXlab platform.
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mechanisms and kinetics of wc co cr high velocity oxy fuel Thermal Spray Coating degradation in corrosive environments
Journal of Thermal Spray Technology, 2006Co-Authors: V. A.d. Souza, Anne NevilleAbstract:In this work, aspects of the corrosion behavior of WC-Co−Cr high velocity oxy-fuel (HVOF) Thermal Spray Coatings have been assessed using a combination of x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) to understand the corrosion mechanisms and, in particular, the electrochemical interactions between phases. Direct curent electrochemical accelerated corrosion techniques (potentiodynamic and potentiostatic tests) were performed to evaluate the corrosion kinetics of the Coating. After the corrosion tests, the solution was analyzed using the inductively coupled plasma (ICP) technique, and a considerable amount of dissolved tungsten was detected. By combining information from XPS, SEM, ICP, and anodic polarization results, it is possible to propose a number of key reactions that can take place during WC-Co−Cr Coating degradation, thus enabling the susceptible components of the Coating to be identified. The implications of these findings for Coating durability are discussed.
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corrosion and synergy in a wccocr hvof Thermal Spray Coating understanding their role in erosion corrosion degradation
Wear, 2005Co-Authors: V. A.d. Souza, Anne NevilleAbstract:Abstract The material degradation of a high velocity oxy-fuel (HVOF) WC Co Cr Thermal Spray Coating is addressed in this paper focusing on the effect of corrosion and the degradation caused by the interaction between corrosion and erosion (synergy) on the overall material loss in erosion–corrosion environments. The mechanical and electrochemical components, which contribute to degradation are isolated and evaluated using an experimental protocol comprising electrochemical techniques and scanning electron microscopy (SEM). Tests under erosion–corrosion conditions were performed in 3.5% NaCl solution with silica sand concentrations of 200, 500 and 1000 mg/l, at two temperatures (20 and 50 °C) and using an impingement velocity of 17 m/s. Austenitic (UNS S31603) and super duplex (UNS S32760) stainless steels were used as a reference and the performance of these three materials is presented. The results show that corrosion and corrosion–erosion interactions play an important role in the overall material degradation of the HVOF Coating and that the dominance of each process is critically dependent on the environment. Some discussion of potential means of improving the Coating durability is presented through consideration of the dominant processes in erosion–corrosion.
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Corrosion and synergy in a WC-Co-Cr HVOF Thermal Spray Coating - Understanding their role in erosion-corrosion degradation
Wear, 2005Co-Authors: V. A.d. Souza, Anne NevilleAbstract:The material degradation of a high velocity oxy-fuel (HVOF) WCCoCr Thermal Spray Coating is addressed in this paper focusing on the effect of corrosion and the degradation caused by the interaction between corrosion and erosion (synergy) on the overall material loss in erosion-corrosion environments. The mechanical and electrochemical components, which contribute to degradation are isolated and evaluated using an experimental protocol comprising electrochemical techniques and scanning electron microscopy (SEM). Tests under erosion-corrosion conditions were performed in 3.5% NaCl solution with silica sand concentrations of 200, 500 and 1000 mg/l, at two temperatures (20 and 50 °C) and using an impingement velocity of 17 m/s. Austenitic (UNS S31603) and super duplex (UNS S32760) stainless steels were used as a reference and the performance of these three materials is presented. The results show that corrosion and corrosion-erosion interactions play an important role in the overall material degradation of the HVOF Coating and that the dominance of each process is critically dependent on the environment. Some discussion of potential means of improving the Coating durability is presented through consideration of the dominant processes in erosion-corrosion. © 2004 Elsevier B.V. All rights reserved.
J. Mostaghimi - One of the best experts on this subject based on the ideXlab platform.
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Splats Formation, Interaction and Residual Stress Evolution in Thermal Spray Coating Using a Hybrid Computational Model
Journal of Thermal Spray Technology, 2019Co-Authors: Abba A. Abubakar, A F M Arif, Syed Sohail Akhtar, J. MostaghimiAbstract:Due to the multilayered pattern of Coating deposition, residual stresses are commonly developed in Thermal Spray Coatings (TSCs). The large deformation, complex interaction and material mismatch are the main contributing factors to residual stress formation. The constitutive behavior and lifetime are directly dependent on the nature and extent of the residual stress field. In the present study, a computational approach for effective prediction of residual stress evolution in TSCs has been proposed. The proposed approach is hybrid in the sense that it combines “point cloud” (PC) and finite elements (FE) to model the residual stresses. Sprayed droplets deposition and associated deformations are captured on PC using smooth particle hydrodynamics, a popular meshless approach for modeling of violent fluid flows. The conversion of deformed droplets from PC to FE domains is done using several recent algorithms for point cloud processing. Then, conventional FE schemes are used to model the heat transfer and structural deformation occurring during the process. The proposed approach has been found to be effective in predicting residual stress evolution in Thermal barrier Coatings (TBCs). It can capture the effects of microstructural defects (such as pores and cracks) and interaction of process parameters on residual stress distribution.
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3 4 residual stresses in Thermal Spray Coating
Reference Module in Materials Science and Materials Engineering#R##N#Comprehensive Materials Finishing, 2017Co-Authors: A F M Arif, Khaled S Alathel, J. MostaghimiAbstract:Residual stresses generated in Coatings during Thermal Spraying plays an important role on the service life and interfacial adhesion. Their magnitude and distributions are affected by both materials and processing parameters. In the introduction section of this chapter, the importance and sources of residual stresses are discussed. In the following sections, various experimental and numerical techniques used for the estimation of residual stresses in Thermal Spray Coating have been discussed.
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Thermal Spray Coating: A New Way of Protecting Wood
Bioresources, 2016Co-Authors: Mojgan Nejad, J. Mostaghimi, Romina Shafaghi, Larry Pershin, Paul A. CooperAbstract:Thermal Spray technology was used to apply a thin layer of copper (Cu metal as an antimicrobial Coating) on the surfaces of a number of different solid woods and medium-density fiberboard (MDF) wood composites. The adhesion of a Cu Coating to Swietenia macrophylla (mahogany), Quercus (oak), Acer saccharinum (silver maple), Picea (spruce), Pinus strobus (white pine), and MDF was evaluated by a pull-off adhesion test. The resistance of Cu-coated samples to mildew, decay fungi, and water uptake was assessed in the lab. Also, the weathering performance of Cu-coated untreated and heat-treated spruce was evaluated. After proper surface preparation, the adhesion of Cu Coatings to hardwood and softwood samples was considered very good, and the adhesion of the Cu Coating to MDF was much stronger than the internal bond strength of MDF itself. The Cu Coating effectively protected the wood from decay fungi and mildew, while it had no effect on the rate of water absorption and desorption from the wood. After one year of natural weathering in Toronto, Canada, the Cu-coated heat-treated spruce samples had significantly fewer checks than coated, untreated wood. Thermal Spray copper Coating proved to have the potential to protect wood from biological degradation while also serving as an antimicrobial Coating.
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a stochastic model to simulate the formation of a Thermal Spray Coating
Journal of Thermal Spray Technology, 2003Co-Authors: R Ghafouriazar, J. Mostaghimi, Sanjeev Chandra, M CharmchiAbstract:We present a three-dimensional, stochastic model of Thermal Spray Coating. It is capable of predicting Coating porosity, thickness, roughness, and the variation of these properties with Spray parameters. The model assigns impact properties to molten droplets landing on the substrate by generating random values of process parameters, assuming that these properties follow normal distributions with user-specified means and standard deviations. We prescribed rules to calculate splat sizes after droplet impact and their interaction with each other. Porosity is assumed to be solely due to the curl-up of the splats as a result of Thermal stresses. We use a Cartesian grid to define the computational domain and to track the shape and position of the deposited Coating. The surface of the Coating and the location of pores within it are specified using a variable known as the “volume fraction,” defined as the fraction of the volume of a computational cell occupied by Coating material. Results are given for the variation of Coating porosity, thickness and roughness with varying particle speed, size, and Spraying gun speed. Predicted trends agree with experimental observation.
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modeling Thermal Spray Coating processes a powerful tool in design and optimization
Surface & Coatings Technology, 2003Co-Authors: J. Mostaghimi, R Ghafouriazar, Sanjeev Chandra, Ali DolatabadiAbstract:Abstract Widespread adoption of Thermal Spray technology requires the ability to apply a variety of Coating materials, suited to each new application. Understanding the dependence of the microstructure of Spray Coatings on operating conditions of the Thermal Spray system is of great practical interest. To obtain good quality Coatings the Spray parameters must be selected carefully, and due to the large variety in process parameters, much trial and error goes into optimizing the process for each specific Coating and substrate combinations. In this paper a complete model of the High Velocity Oxy–Fuel (HVOF) Spray Coating process is presented, including modeling three distinct sub-processes: Spray parameters such as particle size, temperature, velocity, and impact points; particle impact and splat formation; and the Coating microstructure including formation of porosity.
V. A.d. Souza - One of the best experts on this subject based on the ideXlab platform.
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mechanisms and kinetics of wc co cr high velocity oxy fuel Thermal Spray Coating degradation in corrosive environments
Journal of Thermal Spray Technology, 2006Co-Authors: V. A.d. Souza, Anne NevilleAbstract:In this work, aspects of the corrosion behavior of WC-Co−Cr high velocity oxy-fuel (HVOF) Thermal Spray Coatings have been assessed using a combination of x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) to understand the corrosion mechanisms and, in particular, the electrochemical interactions between phases. Direct curent electrochemical accelerated corrosion techniques (potentiodynamic and potentiostatic tests) were performed to evaluate the corrosion kinetics of the Coating. After the corrosion tests, the solution was analyzed using the inductively coupled plasma (ICP) technique, and a considerable amount of dissolved tungsten was detected. By combining information from XPS, SEM, ICP, and anodic polarization results, it is possible to propose a number of key reactions that can take place during WC-Co−Cr Coating degradation, thus enabling the susceptible components of the Coating to be identified. The implications of these findings for Coating durability are discussed.
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corrosion and synergy in a wccocr hvof Thermal Spray Coating understanding their role in erosion corrosion degradation
Wear, 2005Co-Authors: V. A.d. Souza, Anne NevilleAbstract:Abstract The material degradation of a high velocity oxy-fuel (HVOF) WC Co Cr Thermal Spray Coating is addressed in this paper focusing on the effect of corrosion and the degradation caused by the interaction between corrosion and erosion (synergy) on the overall material loss in erosion–corrosion environments. The mechanical and electrochemical components, which contribute to degradation are isolated and evaluated using an experimental protocol comprising electrochemical techniques and scanning electron microscopy (SEM). Tests under erosion–corrosion conditions were performed in 3.5% NaCl solution with silica sand concentrations of 200, 500 and 1000 mg/l, at two temperatures (20 and 50 °C) and using an impingement velocity of 17 m/s. Austenitic (UNS S31603) and super duplex (UNS S32760) stainless steels were used as a reference and the performance of these three materials is presented. The results show that corrosion and corrosion–erosion interactions play an important role in the overall material degradation of the HVOF Coating and that the dominance of each process is critically dependent on the environment. Some discussion of potential means of improving the Coating durability is presented through consideration of the dominant processes in erosion–corrosion.
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Corrosion and synergy in a WC-Co-Cr HVOF Thermal Spray Coating - Understanding their role in erosion-corrosion degradation
Wear, 2005Co-Authors: V. A.d. Souza, Anne NevilleAbstract:The material degradation of a high velocity oxy-fuel (HVOF) WCCoCr Thermal Spray Coating is addressed in this paper focusing on the effect of corrosion and the degradation caused by the interaction between corrosion and erosion (synergy) on the overall material loss in erosion-corrosion environments. The mechanical and electrochemical components, which contribute to degradation are isolated and evaluated using an experimental protocol comprising electrochemical techniques and scanning electron microscopy (SEM). Tests under erosion-corrosion conditions were performed in 3.5% NaCl solution with silica sand concentrations of 200, 500 and 1000 mg/l, at two temperatures (20 and 50 °C) and using an impingement velocity of 17 m/s. Austenitic (UNS S31603) and super duplex (UNS S32760) stainless steels were used as a reference and the performance of these three materials is presented. The results show that corrosion and corrosion-erosion interactions play an important role in the overall material degradation of the HVOF Coating and that the dominance of each process is critically dependent on the environment. Some discussion of potential means of improving the Coating durability is presented through consideration of the dominant processes in erosion-corrosion. © 2004 Elsevier B.V. All rights reserved.
Atsushi Yanagisawa - One of the best experts on this subject based on the ideXlab platform.
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aluminizing of tial based alloy using Thermal Spray Coating
Surface & Coatings Technology, 2011Co-Authors: Tomohiro Sasaki, Takahiro Yagi, Takehiko Watanabe, Atsushi YanagisawaAbstract:Abstract Coating of aluminide on a TiAl-based alloy (49.1 at.% Al) was carried out by Thermal Spraying pure aluminum and subsequent diffusion treatment at 1100 °C. The growth of a Ti–Al intermetallic layer in the Coating layers during diffusion treatment for 120–1800 s as well as the oxidation resistance of the aluminized TiAl-based alloy was investigated. The outermost surface layer was comprised of Al-rich intermetallic TiAl 3 and contained pores. In contrast, an Al concentration gradient layer consisting of Ti 2 Al 5 , TiAl 2 , and Al-rich TiAl containing 55 at.% Al was formed between the outermost layer and the substrate. The thickness of the outermost layer decreased with increasing diffusion time, while the thickness of the intermediate layer grew to approximately 30 μm. In addition, the Coating/substrate interface changed from a wavy to a linear form with the growth of the intermediate layer. The aluminized Coating, at all diffusion times, showed good oxidation resistance in cyclic oxidation tests at 900 °C in air.
Herman Jacobus Cornelis Voorwald - One of the best experts on this subject based on the ideXlab platform.
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fatigue in aisi 4340 steel Thermal Spray Coating by hvof for aeronautic application
Procedia Engineering, 2010Co-Authors: R G Bonora, Herman Jacobus Cornelis Voorwald, Maria Odila Hilario Cioffi, G S, L F V SantosAbstract:Currently, high-strength materials, particularly AISI 4340 steel, are used in several landing gear components. Due to the high resistance to wear and corrosion required, the components are usually Coating by hard chromium. This treatment produces waste, such as Cr+6 (hexavalent chromium), generally after applying the Coating of hard chromium which is harmful to health and the environment. The process HVOF (High-velocity-oxygen-fuel) is considered a promising technique for deposition of hard chromium alternative Coatings, for example, Coatings based on tungsten carbide. This technique provides high hardness and good wear strength and more resistance to fatigue when compared to AISI 4340 hard chromium coated. To minimize loss fatigue due to the process of deposition, shot peening is used to obtain a compressive residual stress. The aim of this study was to analyze the effects of the tungsten carbide Thermal Spray Coating applied by the HVOF, in comparison to the conventional hard chromium electroplating on the AISI 4340 high strength steel behavior in fatigue. Optical microscopy and scanning electron microscopy were used to observe crack origin sites, thickness and adhesion of the Coating.
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evaluation of wc 10ni Thermal Spray Coating with shot peening on the fatigue strength of aisi 4340 steel
Procedia Engineering, 2010Co-Authors: Gilson Silva, Maria Odila Hilario Cioffi, Herman Jacobus Cornelis Voorwald, L F S Vieira, R G BonoraAbstract:Fatigue failure is a result of a crack initiation and propagation, in consequence of a cyclical load. In aeronautical components as landing gear the fatigue strength is an important parameter to be considered in project, as well as the corrosion and wear resistance. The Thermal Sprayed HVOF technology it’s normally used to protect components against wear and corrosion, and are being considerate an alternative to replace chromium by the aeronautical industry. With respect to fatigue life, the HVOF technique induces residual stress on the interface. In the case of tensile residual stresses, the initiation and propagation phases of fatigue process are accelerated; on the other hand, compressive residual stresses close to the surface may increase fatigue life. The technique to improve the coated materials fatigue strength is the shot peening process, which induces residual stress in the surface in order to delay the nucleation and propagation process. The aim of present study is to compare the influence of WC-10 Ni Coating applied by HVOF on the fatigue strength of AISI 4340 steel, with and without shot peening. S-N curves were obtained in axial fatigue tests for material base, and tungsten carbide coated specimens.
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effects of tungsten carbide Thermal Spray Coating by hp hvof and hard chromium electroplating on aisi 4340 high strength steel
Surface & Coatings Technology, 2001Co-Authors: Marcelino P Nascimento, R C Souza, Ivancy M Miguel, W L Pigatin, Herman Jacobus Cornelis VoorwaldAbstract:Abstract In cases of decorative and functional applications, chromium results in protection against wear and corrosion combined with chemical resistance and good lubricity. However, pressure to identify alternatives or to improve conventional chromium electroplating mechanical characteristics has increased in recent years, related to the reduction in the fatigue strength of the base material and to environmental requirements. The high efficiency and fluoride-free hard chromium electroplating is an improvement to the conventional process, considering chemical and physical final properties. One of the most interesting, environmentally safer and cleaner alternatives for the replacement of hard chrome plating is tungsten carbide Thermal Spray Coating, applied by the high velocity oxy-fuel (HVOF) process. The aim of this study was to analyse the effects of the tungsten carbide Thermal Spray Coating applied by the HP/HVOF process and of the high efficiency and fluoride-free hard chromium electroplating (in the present paper called ‘accelerated’), in comparison to the conventional hard chromium electroplating on the AISI 4340 high strength steel behaviour in fatigue, corrosion, and abrasive wear tests. The results showed that the Coatings were damaging to the AISI 4340 steel behaviour when submitted to fatigue testing, with the tungsten carbide Thermal Spray Coatings showing the better performance. Experimental data from abrasive wear tests were conclusive, indicating better results from the WC Coating. Regarding corrosion by salt Spray test, both Coatings were completely corroded after 72 h exposure. Scanning electron microscopy technique (SEM) and optical microscopy were used to observe crack origin sites, thickness and adhesion in all the Coatings and microcrack density in hard chromium electroplatings, to aid in the results analysis.