Skip Nav Destination
Close Modal
Search Results for
porosity
Update search
Filter
- Title
- Authors
- Author Affiliations
- Full Text
- Abstract
- Keywords
- DOI
- ISBN
- EISBN
- Issue
- ISSN
- EISSN
- Volume
- References
Filter
- Title
- Authors
- Author Affiliations
- Full Text
- Abstract
- Keywords
- DOI
- ISBN
- EISBN
- Issue
- ISSN
- EISSN
- Volume
- References
Filter
- Title
- Authors
- Author Affiliations
- Full Text
- Abstract
- Keywords
- DOI
- ISBN
- EISBN
- Issue
- ISSN
- EISSN
- Volume
- References
Filter
- Title
- Authors
- Author Affiliations
- Full Text
- Abstract
- Keywords
- DOI
- ISBN
- EISBN
- Issue
- ISSN
- EISSN
- Volume
- References
Filter
- Title
- Authors
- Author Affiliations
- Full Text
- Abstract
- Keywords
- DOI
- ISBN
- EISBN
- Issue
- ISSN
- EISSN
- Volume
- References
Filter
- Title
- Authors
- Author Affiliations
- Full Text
- Abstract
- Keywords
- DOI
- ISBN
- EISBN
- Issue
- ISSN
- EISSN
- Volume
- References
NARROW
Format
Topics
Subjects
Article Type
Volume Subject Area
Date
Availability
1-20 of 3128
Search Results for porosity
Follow your search
Access your saved searches in your account
Would you like to receive an alert when new items match your search?
1
Sort by
Proceedings Papers
Optimization of High Porosity Thermal Barrier Coatings Generated with a Porosity Former
Available to Purchase
ITSC2014, Thermal Spray 2014: Proceedings from the International Thermal Spray Conference, 680-685, May 21–23, 2014,
... with NiCoCrAlY bond coats. The coatings obtained were evaluated based on thermal conductivity, thermocyclic fatigue life, and morphology, which are shown to correlate with spray parameters and in-flight particle properties. air plasma spraying dysprosia stabilized zirconia high-porosity thermal barrier...
Abstract
View Papertitled, Optimization of High <span class="search-highlight">Porosity</span> Thermal Barrier Coatings Generated with a <span class="search-highlight">Porosity</span> Former
View
PDF
for content titled, Optimization of High <span class="search-highlight">Porosity</span> Thermal Barrier Coatings Generated with a <span class="search-highlight">Porosity</span> Former
Dysprosia stabilized zirconia coatings with large globular pores have good potential as TBC topcoats. In previous work, such coatings have been produced by air plasma spraying with the aid of a polymer pore former. The aim of this work is to optimize the spraying parameters. A design of experiments approach was used to create a two-level full factorial test matrix based on spray distance, powder feed rate, and hydrogen flow. An agglomerated and sintered dysprosia stabilized zirconia (DySZ) powder mixed with polymer particles was sprayed on Hastelloy X substrates that had been prepared with NiCoCrAlY bond coats. The coatings obtained were evaluated based on thermal conductivity, thermocyclic fatigue life, and morphology, which are shown to correlate with spray parameters and in-flight particle properties.
Proceedings Papers
Effects of Polymer Crystallinity on Deposition Efficiency and Porosity in Cold Spray of PEKK
Available to Purchase
ITSC 2022, Thermal Spray 2022: Proceedings from the International Thermal Spray Conference, 82-88, May 4–6, 2022,
... material and quantitative responses to variation in crystallinity were evaluated through a suite of analyses. DE of the materials was assessed gravimetrically, deposit porosity was evaluated by scanning electron microscopy, and thermophysical changes to the feedstock during the spray cycle were determined...
Abstract
View Papertitled, Effects of Polymer Crystallinity on Deposition Efficiency and <span class="search-highlight">Porosity</span> in Cold Spray of PEKK
View
PDF
for content titled, Effects of Polymer Crystallinity on Deposition Efficiency and <span class="search-highlight">Porosity</span> in Cold Spray of PEKK
Polymer cold spray has yielded lower deposition efficiency (DE) and quality deposits compared to metal cold spray. The disparity stems from metals being studied far longer than polymers in cold spray; in addition, polymers exhibit richer thermo-mechanical behavior. An experimental study was conducted to examine the effects of polymer feedstock degree of crystallinity (D) on cold sprayed deposits of polyetherketoneketone (PEKK), a thermoplastic used in aerospace and other high-performance applications. As deposition relies on the plastic deformation of the impacting particle, polymers with high D may inhibit deposition, reducing deposit quality and efficiency. This study evaluates three PEKK grades produced using different ratios of terephthalic (T) to isophthalic (I) monomer moieties (T/I = 60/40, 70/30, 80/20). The ratios control D, with higher proportions of T monomers corresponding to higher crystallization rates and degrees of crystallinity. A parametric study was completed to evaluate functional process set points of system carrier gas temperature and powder mass flow rate. Using operational parameters common among the PEKK grades, spray cycles were completed for each material and quantitative responses to variation in crystallinity were evaluated through a suite of analyses. DE of the materials was assessed gravimetrically, deposit porosity was evaluated by scanning electron microscopy, and thermophysical changes to the feedstock during the spray cycle were determined by differential scanning calorimetry. Overall, we found that cold spray processing of powders of lower D formed less porous deposits with a higher DE than more crystalline powders sprayed at the same process conditions. PEKK grades with lower T/I ratios achieved DEs in the range of 60-75%, whereas the most T enriched grade only reached ~10% DE.
Proceedings Papers
A Machine Learning Based Approach for Cold Spray Deposition Porosity Prediction from Processing Parameters
Available to Purchase
ITSC 2022, Thermal Spray 2022: Proceedings from the International Thermal Spray Conference, 961-976, May 4–6, 2022,
... in this work to predict the coating properties. A machine learning (ML)-based data driven platform for determining the deposition porosity for cold sprayed deposition with the goal of reducing product cost and time has been developed. In this work, five ML models - Linear Regression, Decision Tree Regression...
Abstract
View Papertitled, A Machine Learning Based Approach for Cold Spray Deposition <span class="search-highlight">Porosity</span> Prediction from Processing Parameters
View
PDF
for content titled, A Machine Learning Based Approach for Cold Spray Deposition <span class="search-highlight">Porosity</span> Prediction from Processing Parameters
Cold spray is a high-speed solid state deposition technique which allows for fabricating coatings and free standings structures by careful tuning of process parameters. However due to the complex dependencies of the process parameters a machine learning approach is utilized in this work to predict the coating properties. A machine learning (ML)-based data driven platform for determining the deposition porosity for cold sprayed deposition with the goal of reducing product cost and time has been developed. In this work, five ML models - Linear Regression, Decision Tree Regression and Random Forest Regression, XGBRegressor and LGBMRegressor are compared for the prediction of coating porosity from spray and material parameters namely Heat Capacity Ratio of carrier gas, Processing Gas Temperature, Processing gas pressure, Standoff Distance, Average Powder Diameter, Powder Material Density, and the Substrate density. A total number of 227 data sets were extracted from an extensive literature survey on cold spray deposition of metal/alloy powders which were used to train the ML models. The data analysis showed strong and weak correlations of several processing parameters with the coating porosity. The processing gas temperature and pressure have a negative and average powder diameter has a positive correlation with the deposition porosity. The coating porosities of 10 unknown sets (which were not included in the training or the validation data sets) of processing parameters predicted by the trained algorithms were compared with each other. Decision Tree regression algorithm showed the most appropriate predictions with R2 Fit of 0.75 and MAE of 2.93, while the Linear Regression model did the worst predictions with R2 Fit of 0.27 and MAE of 5.064.
Proceedings Papers
Three-Dimensional Simulation of Porosity in Plasma-Sprayed Alumina using Microtomography and Electrochemical Impedance Spectrometry for Finite Element Modeling of Properties
Available to Purchase
ITSC 2008, Thermal Spray 2008: Proceedings from the International Thermal Spray Conference, 984-989, June 2–4, 2008,
... spectroscopy finite element analysis microtomography plasma spraying porosity International Thermal Spray Conference & Exposition E. Lugscheider, editor, p 984-989 httpsdoi.org/10.31399/asm.cp.itsc2008p0984 Copyright © 2008 Verlag für Schweißenund verwandte Verfahren DVS-Verlag GmbH All rights reserved...
Abstract
View Papertitled, Three-Dimensional Simulation of <span class="search-highlight">Porosity</span> in Plasma-Sprayed Alumina using Microtomography and Electrochemical Impedance Spectrometry for Finite Element Modeling of Properties
View
PDF
for content titled, Three-Dimensional Simulation of <span class="search-highlight">Porosity</span> in Plasma-Sprayed Alumina using Microtomography and Electrochemical Impedance Spectrometry for Finite Element Modeling of Properties
Moving from a 2-dimensional to a 3-dimensional approach to microstructure and properties has been expected eagerly for a long while to result in a dramatic increase in the knowledge of thermally-sprayed processes and coatings. To meet these expectations, in the present work, microtomography and electrochemical impedance spectroscopy (EIS) were carried out to simulate the microstructure of plasma-sprayed alumina. As-sprayed and excimer laser-processed deposits were studied. Some unexpected but relevant results, e.g. regarding pore orientation in the coatings, could be obtained. EIS simulation led to the establishing of an electrical circuit equivalent to the microstructure which simulated the insulating properties as a function of interfaces and pore interconnection. The latter was studied by microtomography. From this 3-dimensional simulation, a finite element analysis of mechanical properties was developed and compared to experimental measurements. Using this approach to microstructure and properties, excimer laser surface processing was shown to be an innovative process to modify insulating characteristics of plasma-sprayed alumina.
Proceedings Papers
Innovative Testing Method for Interconnected Porosity of Thermally Sprayed Ceramic Coatings Using Electroplating
Available to Purchase
ITSC 2011, Thermal Spray 2011: Proceedings from the International Thermal Spray Conference, 1017-1020, September 27–29, 2011,
... Abstract New concept and method of testing for the interconnecting porosity of thermally sprayed nonconductive ceramic coatings is proposed. This process is useful to differentiate the open porosity from the closed porosity. Thermally sprayed ceramic coating with metallic substrate is plated...
Abstract
View Papertitled, Innovative Testing Method for Interconnected <span class="search-highlight">Porosity</span> of Thermally Sprayed Ceramic Coatings Using Electroplating
View
PDF
for content titled, Innovative Testing Method for Interconnected <span class="search-highlight">Porosity</span> of Thermally Sprayed Ceramic Coatings Using Electroplating
New concept and method of testing for the interconnecting porosity of thermally sprayed nonconductive ceramic coatings is proposed. This process is useful to differentiate the open porosity from the closed porosity. Thermally sprayed ceramic coating with metallic substrate is plated, and the intergranular gaps in the coating are filled by deposited metal. Typically, 304 stainless steel substrate deposited with atmospheric plasma sprayed alumina coating is immersed in copper(II) sulphate bath, and electroplated. Inward of the alumina coating, plating solution penetrates toward the interface of coating/substrate via interconnected porosity, and attains the coating-substrate interface to deposit metallic copper. Deposit of copper is gradually grown up along the coating intergranular. The exposure of deposited copper on the coating surface can be visible. Because these phenomena occur only in the interconnected pore structure, it is easy to differentiate the interconnected porosity from the closed porosity. Also the proposed process suggests the unprecedented possibility of manufacturing method of three-dimensional structure of thermally sprayed ceramic coating.
Proceedings Papers
Absolute Coating Porosity Measurement Using Image Analysis
Available to Purchase
ITSC1998, Thermal Spray 1998: Proceedings from the International Thermal Spray Conference, 917-922, May 25–29, 1998,
... Abstract This paper describes the procedure that has been developed for absolute porosity measurement using Image Analysis (IA). Because of the crumbly nature of the composite substrate, it was not possible to proceed with standard method. The IA conducted on Optical Microscopy did not show...
Abstract
View Papertitled, Absolute Coating <span class="search-highlight">Porosity</span> Measurement Using Image Analysis
View
PDF
for content titled, Absolute Coating <span class="search-highlight">Porosity</span> Measurement Using Image Analysis
This paper describes the procedure that has been developed for absolute porosity measurement using Image Analysis (IA). Because of the crumbly nature of the composite substrate, it was not possible to proceed with standard method. The IA conducted on Optical Microscopy did not show enough contrast between pores and other features to be automated. The IA conducted on Scanning Electron Microscopy (SEM) with back scattered electron imaging gives enough contrast for automatic threshold determination. The SEM magnification is a parameter to be considered because it filters the information. Three frames at 500X magnification are enough for measuring the porosity of homogeneous supersonic induction plasma sprayed 18 mm samples (thickness 50-100 µm). The established calibration almost shows a 1 to 1 ratio for the image analysis as measured porosity versus the Archimedean porosity. Application of this absolute porosity determination by IA can be found in the Functionally Graded Materials (FGM) which composition is not constant over the layer thickness.
Proceedings Papers
Investigation of the Effect of Porosity Content on the Flexural Behavior of Nickel Foam Core Sandwich Structures with Arc Sprayed Alloy 625 Skin
Available to Purchase
ITSC2014, Thermal Spray 2014: Proceedings from the International Thermal Spray Conference, 461-466, May 21–23, 2014,
... porosity on flexural rigidity and overall mechanical behavior are investigated. The ductility of porous alloy 625 skins was improved after heat treatment at 1100 °C for 3 h. flexural rigidity Inconel 625 coatings nickel foam porosity sandwich structures twin wire arc spraying International...
Abstract
View Papertitled, Investigation of the Effect of <span class="search-highlight">Porosity</span> Content on the Flexural Behavior of Nickel Foam Core Sandwich Structures with Arc Sprayed Alloy 625 Skin
View
PDF
for content titled, Investigation of the Effect of <span class="search-highlight">Porosity</span> Content on the Flexural Behavior of Nickel Foam Core Sandwich Structures with Arc Sprayed Alloy 625 Skin
In this study, porous and dense layers of alloy 625 are deposited on nickel foam sheets using a modified twin wire arc spraying process. Sandwich panels with arc-sprayed alloy 625 skins on nickel foam cores were fabricated then subjected to four-point bend testing. The effects of skin porosity on flexural rigidity and overall mechanical behavior are investigated. The ductility of porous alloy 625 skins was improved after heat treatment at 1100 °C for 3 h.
Proceedings Papers
Al-12Si Cold Sprayed Coatings with Controlled Porosity
Available to Purchase
ITSC 2008, Thermal Spray 2008: Proceedings from the International Thermal Spray Conference, 1272-1276, June 2–4, 2008,
... Abstract The demand of industry for metallic thermal sprayed coatings with controlled porosity until now is fulfilled by the spraying of metallic powders mixed with additives (organic element in many cases) which play the role of pores. The new technology of cold spray can lead to the formation...
Abstract
View Papertitled, Al-12Si Cold Sprayed Coatings with Controlled <span class="search-highlight">Porosity</span>
View
PDF
for content titled, Al-12Si Cold Sprayed Coatings with Controlled <span class="search-highlight">Porosity</span>
The demand of industry for metallic thermal sprayed coatings with controlled porosity until now is fulfilled by the spraying of metallic powders mixed with additives (organic element in many cases) which play the role of pores. The new technology of cold spray can lead to the formation of innovate coatings of controlled porosity by using pure metallic (or alloy) powder without any further addition. A fine Al-12Si powder (<45 µm) was sprayed with a cold spray system (CGT Kinetic 3000-M) on stainless steel substrate under different spraying conditions. In the present study, the new polymeric nozzle PBI-33 of CGT was used for the formation of al-based coatings. The microstructure, the porosity, the Vickers microhardness and the superficial Rockwell hardness (R15Y) of the produced coatings are examined.
Proceedings Papers
Effect of Heat Treatment on Porosity and Corrosion Performance of Cold Sprayed Titanium Deposits
Available to Purchase
ITSC 2010, Thermal Spray 2010: Proceedings from the International Thermal Spray Conference, 379-384, May 3–5, 2010,
... resistant barrier coatings. However, to be effective a barrier coating must not allow ingress of a corrosive liquid and hence must have minimal interconnected porosity. Thus the aim of the present study was to investigate the effects of processing, including a post-spray annealing treatment, on the deposit...
Abstract
View Papertitled, Effect of Heat Treatment on <span class="search-highlight">Porosity</span> and Corrosion Performance of Cold Sprayed Titanium Deposits
View
PDF
for content titled, Effect of Heat Treatment on <span class="search-highlight">Porosity</span> and Corrosion Performance of Cold Sprayed Titanium Deposits
Cold gas dynamic spraying (CGDS) can be used to deposit oxygen sensitive materials, such as titanium, without significant chemical degradation of the powder and with minimal heating of the substrate. The process is thus believed to have potential for the deposition of corrosion resistant barrier coatings. However, to be effective a barrier coating must not allow ingress of a corrosive liquid and hence must have minimal interconnected porosity. Thus the aim of the present study was to investigate the effects of processing, including a post-spray annealing treatment, on the deposit meso- and microstructures and corrosion behavior. Commercially pure titanium powder was deposited using pre-heated nitrogen as main and powder carrier gas using a CGT Kinetiks 4000 system to produce coatings on stainless steel. Selected coatings were debonded from the substrate, and the resultant free standing deposits heat treated at 1050° C in vacuum for 60 minutes. Changes in microhardness were measured and correlated with microstructural changes. Optical microscopy, scanning electron microscopy, X-ray diffraction (XRD), helium pycnometry and mercury porosimetry were all employed to examine the microstructural characteristics of coatings and free standing deposits, before and after heat treatment. Their corrosion performance was also investigated using potentiodynamic polarization tests in 3.5 wt% NaCl. The influences of heat treatment and corrosion behavior will be analyzed and discussed in terms of pores structure evolution and microstructural changes.
Proceedings Papers
Effect of Spray Parameters on Porosity and Lifetime of Suspension Plasma Sprayed Thermal Barrier Coatings
Available to Purchase
ITSC 2018, Thermal Spray 2018: Proceedings from the International Thermal Spray Conference, 84-91, May 7–10, 2018,
... microstructure porosity suspension plasma spraying thermal barrier coatings thermal conductivity IITSC 2018 Proceedings of the International Thermal Spray Conference May 7-10, 2018, Orlando, Florida, USA F. Azarmi, K. Balani, T. Eden, T. Hussain, Y.-C. Lau, H. Li, K. Shinoda, F.-L. Toma, J. Veilleux...
Abstract
View Papertitled, Effect of Spray Parameters on <span class="search-highlight">Porosity</span> and Lifetime of Suspension Plasma Sprayed Thermal Barrier Coatings
View
PDF
for content titled, Effect of Spray Parameters on <span class="search-highlight">Porosity</span> and Lifetime of Suspension Plasma Sprayed Thermal Barrier Coatings
Fabrication of Thermal Barrier Coatings (TBCs) with higher lifetime and relatively cheaper processes is of particular interest for gas turbine applications. Suspension Plasma Spray (SPS) is capable of producing coatings with porous columnar structure, and it is also a much cheaper process compared to the conventionally used Electron Beam Physical Vapor Deposition (EB-PVD). Although TBCs fabricated using SPS have lower thermal conductivity as compared to other commonly used processes, they are still not commercialized due to their poor lifetime expectancy. Lifetime of TBCs is highly influenced by the top coat microstructure. The objective of this work was to study the TBCs produced using axial SPS with different process parameters. The bond coat was deposited using High Velocity Air Fuel (HVAF) spray. Influence of the microstructure on lifetime of the coatings was of particular interest and it was determined by thermal cyclic fatigue testing. Thermal conductivity of the coatings was determined by laser flash analysis. The results show that axial SPS could be a promising method of producing TBCs for high temperature gas turbine applications.
Proceedings Papers
Porosity Characterization and Its Effect on Thermal Properties of APS Sprayed Alumina Coatings
Available to Purchase
ITSC 2017, Thermal Spray 2017: Proceedings from the International Thermal Spray Conference, 13-18, June 7–9, 2017,
... were investigated by thermal insulation test and detailed image analysis technique, respectively. The analyzed micro-structural features include the total porosity, pore size (fine, medium, and large) and cracks. All types of cracks were considered in calculations as voids and were evaluated according...
Abstract
View Papertitled, <span class="search-highlight">Porosity</span> Characterization and Its Effect on Thermal Properties of APS Sprayed Alumina Coatings
View
PDF
for content titled, <span class="search-highlight">Porosity</span> Characterization and Its Effect on Thermal Properties of APS Sprayed Alumina Coatings
In the present work, three different APS alumina coatings were fabricated using three fused and crushed alumina powders of different particle size fine, medium and coarse. The influence of the particle size on thermal properties and micro-structural features of the produced coating were investigated by thermal insulation test and detailed image analysis technique, respectively. The analyzed micro-structural features include the total porosity, pore size (fine, medium, and large) and cracks. All types of cracks were considered in calculations as voids and were evaluated according to their sizes as pores. All spray parameters except the particle size were fixed throughout the spraying process. The results revealed that the fine starting powder has produced the densest coating with the lowest total porosity and that the total porosity increases with an increasing particle size. This was expected as powders of smaller particle size will reach a higher in-flight temperature and velocity than powders of bigger particle sizes as long as the same spray parameters are applied. However, a detailed image analysis investigation on the three produced coatings showed that the fraction of fine pores and cracks versus the total porosity is substantially higher in coatings produced by using fine starting powders than those produced using medium and coarse powders. In this work, a connection between the thermal insulation and the porosity fraction, which includes fine pores and cracks, was revealed.
Proceedings Papers
Effect of Spray Parameters on the Microstructure and Porosity Content of Gadolinium Zirconate TBCs Deposited by Suspension Plasma Spray
Available to Purchase
ITSC 2017, Thermal Spray 2017: Proceedings from the International Thermal Spray Conference, 31-35, June 7–9, 2017,
... content in the as sprayed TBCs was analyzed by XRD. The porosity content of the as sprayed TBCs was measured using image analysis. In the SEM analysis, it was observed that a lower solid load content in the suspension favored the formation of a columnar microstructure. Additionally, at lower solid load...
Abstract
View Papertitled, Effect of Spray Parameters on the Microstructure and <span class="search-highlight">Porosity</span> Content of Gadolinium Zirconate TBCs Deposited by Suspension Plasma Spray
View
PDF
for content titled, Effect of Spray Parameters on the Microstructure and <span class="search-highlight">Porosity</span> Content of Gadolinium Zirconate TBCs Deposited by Suspension Plasma Spray
Gadolinium zirconate (GZ) is considered as a promising top coat candidate for high temperature (>1200 °C) thermal barrier coating (TBC) applications. Suspension plasma spray (SPS) technique has shown the capability to generate a wide range of microstructures which includes the more desirable columnar microstructure. In this study, GZ single layer TBCs were deposited by axial SPS process. The variable parameters include the standoff distance, solid load content of the suspension and input power. The cross section and top surface of the as sprayed TBCs were analyzed by SEM. The phase content in the as sprayed TBCs was analyzed by XRD. The porosity content of the as sprayed TBCs was measured using image analysis. In the SEM analysis, it was observed that a lower solid load content in the suspension favored the formation of a columnar microstructure. Additionally, at lower solid load content, increase in standoff distance resulted in columnar microstructure with high porosity content in the TBC. However, with higher solid content suspension and alteration of input power, only a dense vertical cracked microstructure can be obtained.
Proceedings Papers
Porosity Measurements on Heat Treated Suspension Plasma Sprayed YSZ Coatings Using NMR Cryoporometry
Available to Purchase
ITSC 2017, Thermal Spray 2017: Proceedings from the International Thermal Spray Conference, 308-314, June 7–9, 2017,
... Abstract Suspension plasma sprayed (SPS) coatings can be produced with fine powder particles and tailor-made porosity. This allows to achieve low thermal conductivity which makes the coatings attractive as e.g. topcoats in thermal barrier coatings (TBCs). Used in gas turbine applications...
Abstract
View Papertitled, <span class="search-highlight">Porosity</span> Measurements on Heat Treated Suspension Plasma Sprayed YSZ Coatings Using NMR Cryoporometry
View
PDF
for content titled, <span class="search-highlight">Porosity</span> Measurements on Heat Treated Suspension Plasma Sprayed YSZ Coatings Using NMR Cryoporometry
Suspension plasma sprayed (SPS) coatings can be produced with fine powder particles and tailor-made porosity. This allows to achieve low thermal conductivity which makes the coatings attractive as e.g. topcoats in thermal barrier coatings (TBCs). Used in gas turbine applications, the TBCs are exposed to high temperatures which leads to alterations of the microstructure. To obtain coatings with optimized properties, possible microstructure alterations like closing of pores and opening of cracks have to be taken into account. Hence, in this study, TBC topcoats consisting of 8 wt.% yttria-stabilized zirconia (YSZ) were heat treated in air at 1150°C and thereafter investigated using scanning electron microscopy, X-ray diffraction, and nuclear magnetic resonance (NMR) cryoporometry. For all investigated samples, the porosity decreased as a result of the heat treatment. The finer pores and cracks disappeared and the larger pores grew slightly and achieved a more distinct shape as the material seemed to become more compact.
Proceedings Papers
Supersonic Flame Sprayed Cylinder Liner Coatings and the Benefits of their Intrinsic Porosity
Available to Purchase
ITSC 2011, Thermal Spray 2011: Proceedings from the International Thermal Spray Conference, 467-472, September 27–29, 2011,
... is also capable of processing highly corrosion resistant materials like alloys and ceramics to enable the safe utilization of biofuels in modern combustion engines. In addition, specific surface structure of thermal spray coatings, including their intrinsic porosity, shows the benefit of reducing...
Abstract
View Papertitled, Supersonic Flame Sprayed Cylinder Liner Coatings and the Benefits of their Intrinsic <span class="search-highlight">Porosity</span>
View
PDF
for content titled, Supersonic Flame Sprayed Cylinder Liner Coatings and the Benefits of their Intrinsic <span class="search-highlight">Porosity</span>
To meet new regulations and specifications for internal combustion engines, new approaches to significantly decrease fuel consumption and emissions are needed. The deployment of tribologically functional coatings applied by supersonic flame spraying represent a promising technology for achieving these targets. Thermally sprayed coatings can help in improving efficiency of internal combustion engines by reducing the internal friction and improving the durability and wear resistance of the engine’s cylinder wall thereby facilitating extreme engine downsizing concepts. Thermal spraying is also capable of processing highly corrosion resistant materials like alloys and ceramics to enable the safe utilization of biofuels in modern combustion engines. In addition, specific surface structure of thermal spray coatings, including their intrinsic porosity, shows the benefit of reducing the friction by sustaining hydrodynamic friction even in spots with low relative movement, e.g. top and bottom dead center. On top, the open surface porosity can reduce the oil consumption and thereby decrease the polluting emissions of internal combustion engines. The thermally sprayed coatings were applied using HVOF and HVSFS processes deploying various materials, including novel nanostructured powders. The coated cylinders and engines have been compared to state-of-the-art components with respect to friction coefficient, wear and oil consumption.
Proceedings Papers
Impact Mechanics of Spherical Metallic Particles with Uniformly Distributed Porosity
Available to Purchase
ITSC 2019, Thermal Spray 2019: Proceedings from the International Thermal Spray Conference, 846-852, May 26–29, 2019,
... are taken into account as are differences in the initial kinetic energy and strength of the materials. It was found that the influence of porosity increases with impact velocity and that the pores channel stress waves in unique ways not observed for solid particles. The results suggest that using porous...
Abstract
View Papertitled, Impact Mechanics of Spherical Metallic Particles with Uniformly Distributed <span class="search-highlight">Porosity</span>
View
PDF
for content titled, Impact Mechanics of Spherical Metallic Particles with Uniformly Distributed <span class="search-highlight">Porosity</span>
In this study, finite element models are used to simulate the impact of porous WC-Co and Al particles cold sprayed onto substrates of the same materials. Effects of high strain rate, heat generation due to plasticity, interfacial friction, heat transfer, and material damage and failure are taken into account as are differences in the initial kinetic energy and strength of the materials. It was found that the influence of porosity increases with impact velocity and that the pores channel stress waves in unique ways not observed for solid particles. The results suggest that using porous particles for solid-state consolidation, as in cold spraying, could have advantages in terms of energy dissipation, although further investigation is required.
Proceedings Papers
Interconnected Porosity Modification of Plasma Sprayed Alumina Coating Using Excimer Laser Surface Treatment
Available to Purchase
ITSC2012, Thermal Spray 2012: Proceedings from the International Thermal Spray Conference, 521-528, May 21–24, 2012,
... microtomography to evaluate the 3D porosity after laser treatment. Finally, nanoindentation and Electrochemical Impedance Spectroscopy (EIS) were carried out to characterize respectively the mechanical and electrical properties of the modified coating microstructure. The excimer laser surface processing was shown...
Abstract
View Papertitled, Interconnected <span class="search-highlight">Porosity</span> Modification of Plasma Sprayed Alumina Coating Using Excimer Laser Surface Treatment
View
PDF
for content titled, Interconnected <span class="search-highlight">Porosity</span> Modification of Plasma Sprayed Alumina Coating Using Excimer Laser Surface Treatment
Thermally sprayed ceramic coatings such as plasma-sprayed alumina exhibit a composite microstructure due to the presence of defects such as pores, interlamellar and intra-lamellar cracks. These second phase typed features influence the mechanical behaviour of the coating dramatically. In this study, an excimer laser surface treatment of plasma-sprayed alumina surface was developed for the optimization of component properties of a wireline tool used in the oil industry. In contrast to liquid phase treatment realized with CO 2 or YAG laser, an excimer laser processing presents short wavelength which means that for ceramic materials, the energy is absorbed in a region of the surface. This condition leads to surface treatment free of cracks. Effect of laser operating parameters, i.e. wavelength, pulse number and power density, on microstructure and the sealing quality of the coating are discussed. First, surfaces and cross sections of the microstructures were studied using image analysis of scanning electron microscope (SEM). Surface roughness and coating ablation were characterized according to laser treatment. Then, three dimensional (3D) microstructures were obtained using X-ray microtomography to evaluate the 3D porosity after laser treatment. Finally, nanoindentation and Electrochemical Impedance Spectroscopy (EIS) were carried out to characterize respectively the mechanical and electrical properties of the modified coating microstructure. The excimer laser surface processing was shown to be an innovative process to control the insulating characteristics of plasma-sprayed alumina.
Proceedings Papers
Study on Porosity of Plasma Sprayed Coating by Digital Image Analysis Method
Available to Purchase
ITSC 2004, Thermal Spray 2004: Proceedings from the International Thermal Spray Conference, 229-234, May 10–12, 2004,
... Abstract Three kind of commercial ceramics powders, Al 2 O 3 , ZrO 2 and TiO 2 were deposited on 304 stainless steel plates by plasma spraying technique. Their porosities were evaluated with digital image analysis method. As the accuracy of this method depends significantly on metallographic...
Abstract
View Papertitled, Study on <span class="search-highlight">Porosity</span> of Plasma Sprayed Coating by Digital Image Analysis Method
View
PDF
for content titled, Study on <span class="search-highlight">Porosity</span> of Plasma Sprayed Coating by Digital Image Analysis Method
Three kind of commercial ceramics powders, Al 2 O 3 , ZrO 2 and TiO 2 were deposited on 304 stainless steel plates by plasma spraying technique. Their porosities were evaluated with digital image analysis method. As the accuracy of this method depends significantly on metallographic preparation and metallography procedure for coating sample, we studied the effects of surface roughness, magnification and number of fields of view on the porosity. The proper values for the three parameters are discussed.
Proceedings Papers
Analysis of Porosity and Cracks in Cross Sections of Plasma Sprayed Oxide Coatings
Available to Purchase
ITSC 2001, Thermal Spray 2001: Proceedings from the International Thermal Spray Conference, 627-632, May 28–30, 2001,
... Abstract Microstructure of plasma-sprayed thermal barrier coating has an influence on the lifetime under service conditions in aero engine. This paper focuses on problems of preparing and comparing ceramic samples and characterising microstructure features such as porosity and cracks within...
Abstract
View Papertitled, Analysis of <span class="search-highlight">Porosity</span> and Cracks in Cross Sections of Plasma Sprayed Oxide Coatings
View
PDF
for content titled, Analysis of <span class="search-highlight">Porosity</span> and Cracks in Cross Sections of Plasma Sprayed Oxide Coatings
Microstructure of plasma-sprayed thermal barrier coating has an influence on the lifetime under service conditions in aero engine. This paper focuses on problems of preparing and comparing ceramic samples and characterising microstructure features such as porosity and cracks within coating cross sections by image analysis. The results can be used for developing standards and best practices for characterization plasma-sprayed coatings. The methodology was evolved to relate coating microstructure to spraying parameters and properties of coating. It would help to develop new ceramics coatings or optimise them.
Proceedings Papers
Evaluation on Through-Porosity of HVOF Sprayed Coatings
Available to Purchase
ITSC 2002, Thermal Spray 2002: Proceedings from the International Thermal Spray Conference, 681-685, March 4–6, 2002,
... Abstract This study evaluates the through-porosity of HVOF-sprayed Hastelloy C coatings on carbon steel with respect to coating thickness and combustion pressure. The amount of through-porosity in the NiCrMo alloy layer is determined by chemical analysis, using ICP emission spectroscopy...
Abstract
View Papertitled, Evaluation on Through-<span class="search-highlight">Porosity</span> of HVOF Sprayed Coatings
View
PDF
for content titled, Evaluation on Through-<span class="search-highlight">Porosity</span> of HVOF Sprayed Coatings
This study evaluates the through-porosity of HVOF-sprayed Hastelloy C coatings on carbon steel with respect to coating thickness and combustion pressure. The amount of through-porosity in the NiCrMo alloy layer is determined by chemical analysis, using ICP emission spectroscopy, and compared with electrochemical measurements. Paper includes a German-language abstract.
Proceedings Papers
Low Porosity and Fine Coatings Produced by a New Type Nozzle of High Velocity Arc Spray Gun
Available to Purchase
ITSC 2004, Thermal Spray 2004: Proceedings from the International Thermal Spray Conference, 584-587, May 10–12, 2004,
... Abstract Providing for the DZ400 arc spray system, the new design high-velocity arc spray gun with three different nozzles is developed to produce the coatings with the structure of superfine and low porosity. This system can be used to spray the three normal wires of 4Crl3, FeCrAl and 7Crl3...
Abstract
View Papertitled, Low <span class="search-highlight">Porosity</span> and Fine Coatings Produced by a New Type Nozzle of High Velocity Arc Spray Gun
View
PDF
for content titled, Low <span class="search-highlight">Porosity</span> and Fine Coatings Produced by a New Type Nozzle of High Velocity Arc Spray Gun
Providing for the DZ400 arc spray system, the new design high-velocity arc spray gun with three different nozzles is developed to produce the coatings with the structure of superfine and low porosity. This system can be used to spray the three normal wires of 4Crl3, FeCrAl and 7Crl3 (flux cored wires). With the SEM to analysis shape and particles size sprayed by the nozzles by different parameters, as well as with the S-3500N SEM (made by HITACHI) and the INCA ESA (made by OXFORD) identify the content of the oxides, porosity and thickness of the coatings. The result shows that the porosity in the coatings of solid wire is less than 2%, of the flux-cored wires is less than 4%, and the coating sprayed by the nozzle with the secondary supplementary airflow is typically shown to be distributed in the form of high-density lamellar splat structure and the average lamellar thickness is around 5 μm.
1