Special Issue "High Temperature Coatings"

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A special issue of Coatings (ISSN 2079-6412).

Deadline for manuscript submissions: closed (31 May 2015)

Special Issue Editors

Guest Editor
Prof. Dr. Ugo Bardi (Website)

Dipartimento di Scienze della Terra, c/o Dipartimento di Chimica, Polo Scientifico di Sesto Fiorentino, Università di Firenze, Via Della Lastruccia 3, 50019 Sesto Fiorentino (Fi), Italy
Fax: +39 55 457 3120
Interests: coatings and surface engineering; electrodeposition from ionic liquids, with a special view on aluminium coatings; thermal barriers manufacturing, testing, and characterization for the aerospace and energy production industry; scanning probe microscopy (SPM); electron microscopy (SEM, TEM); surface composition measurements; photoelectron spectroscopy (XPS); scanning auger microscopy (SAM); low energy ion scattering (LEIS)
Founding Editor-in-Chief
Guest Editor
Dr. Alessandro Lavacchi

Istituto di Chimica dei Composti OrganoMetallici (ICCOM-CNR), Via Madonna del Piano 10, 50019 Sesto Fiorentino, Firenze, Italy
Phone: +39 55 5225239
Fax: +39 55 5225203
Interests: electrodeposition of materials for renewable energy production; surface engineering; corrosion and corrosion protection; thermal barriers coatings; electron microscopy (SEM, TEM); X-ray techniques for surface structure and composition (XPS, XRF, XRD); electroless deposition of metals and cermet’s; simulation and modelling of complex electrochemical systems

Special Issue Information

Dear Colleagues,

High Temperature Coatings assolve the vital function of protecting the underlying materials from thermal stresses. Their impact in our society is important as these coatings find applications in many crucial sectors as energy production and the aerospace industry. One of the most important contributions of the field of material science research during the last century was the development of the Thermal Barrier Coating (TBC) architecture, now a mature commercial technology and still a very active research field. Researchers from any field are now called from the institutions and the public to contribute to sustainable development. This is a very important opportunity for the High Temperature Coatings community which also can provide several applications in which TBCs and other high temperature coatings increase the efficiency of thermal engines and provide improved performance in other energy applications, such as in Solide Oxide Fuel Cells and in the protection from hot corrosion phenomena occurring in burning biomass. It is a pleasure for us editing this special issue in such an exceptionally active research field. We invite experts to contribute with their original research articles and with manuscripts regarding research ideas envisioning future opportunity for the High Temperature Coatings community also.

Prof. Dr. Ugo Bardi
Dr. Alessandro Lavacchi
Guest Editors

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Coatings is an international peer-reviewed Open Access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 300 CHF (Swiss Francs). English correction and/or formatting fees of 250 CHF (Swiss Francs) will be charged in certain cases for those articles accepted for publication that require extensive additional formatting and/or English corrections.

Keywords

  • hot corrosion protection
  • high temperature oxidation
  • thermal barrier coatings
  • plasma spraying
  • failure mechanism
  • coatings architecture
  • intelligent coatings

Published Papers (7 papers)

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Research

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Open AccessArticle Performance Testing of Suspension Plasma Sprayed Thermal Barrier Coatings Produced with Varied Suspension Parameters
Coatings 2015, 5(3), 338-356; doi:10.3390/coatings5030338
Received: 17 June 2015 / Revised: 20 July 2015 / Accepted: 22 July 2015 / Published: 24 July 2015
Cited by 4 | PDF Full-text (2211 KB) | HTML Full-text | XML Full-text
Abstract
Suspension plasma spraying has become an emerging technology for the production of thermal barrier coatings for the gas turbine industry. Presently, though commercial systems for coating production are available, coatings remain in the development stage. Suitable suspension parameters for coating production remain [...] Read more.
Suspension plasma spraying has become an emerging technology for the production of thermal barrier coatings for the gas turbine industry. Presently, though commercial systems for coating production are available, coatings remain in the development stage. Suitable suspension parameters for coating production remain an outstanding question and the influence of suspension properties on the final coatings is not well known. For this study, a number of suspensions were produced with varied solid loadings, powder size distributions and solvents. Suspensions were sprayed onto superalloy substrates coated with high velocity air fuel (HVAF) -sprayed bond coats. Plasma spray parameters were selected to generate columnar structures based on previous experiments and were maintained at constant to discover the influence of the suspension behavior on coating microstructures. Testing of the produced thermal barrier coating (TBC) systems has included thermal cyclic fatigue testing and thermal conductivity analysis. Pore size distribution has been characterized by mercury infiltration porosimetry. Results show a strong influence of suspension viscosity and surface tension on the microstructure of the produced coatings. Full article
(This article belongs to the Special Issue High Temperature Coatings)
Open AccessArticle Micromechanical Simulation of Thermal Cyclic Behavior of ZrO2/Ti Functionally Graded Thermal Barrier Coatings
Coatings 2015, 5(1), 63-77; doi:10.3390/coatings5010063
Received: 26 November 2014 / Revised: 18 December 2014 / Accepted: 16 February 2015 / Published: 5 March 2015
PDF Full-text (608 KB) | HTML Full-text | XML Full-text
Abstract
This study numerically investigates cyclic thermal shock behavior of ZrO2/Ti functionally graded thermal barrier coatings (FG TBCs) based on a nonlinear mean-field micromechanical approach, which takes into account the time-independent and dependent inelastic deformation, such as plasticity of metals, creep [...] Read more.
This study numerically investigates cyclic thermal shock behavior of ZrO2/Ti functionally graded thermal barrier coatings (FG TBCs) based on a nonlinear mean-field micromechanical approach, which takes into account the time-independent and dependent inelastic deformation, such as plasticity of metals, creep of metals and ceramics, and diffusional mass flow at the ceramic/metal interface. The fabrication processes for the FG TBCs have been also considered in the simulation. The effect of creep and compositional gradation patterns on micro-stress states in the FG TBCs during thermal cycling has been examined in terms of the amplitudes, ratios, maximum and mean values of thermal stresses. The compositional gradation patterns highly affect thermal stress states in case of high creep rates of ZrO2. In comparison with experimental data, maximum thermal stresses, amplitudes and ratios of thermal stresses can be effective parameters for design of such FG TBCs subject to cyclic thermal shock loadings. Full article
(This article belongs to the Special Issue High Temperature Coatings)
Open AccessArticle Thermal Performance of Hollow Clay Brick with Low Emissivity Treatment in Surface Enclosures
Coatings 2014, 4(4), 715-731; doi:10.3390/coatings4040715
Received: 29 July 2014 / Revised: 1 October 2014 / Accepted: 9 October 2014 / Published: 17 October 2014
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Abstract
External walls made with hollow clay brick or block are widely used for their thermal, acoustic and structural properties. However, the performance of the bricks frequently does not conform with the minimum legal requirements or the values required for high efficiency buildings, [...] Read more.
External walls made with hollow clay brick or block are widely used for their thermal, acoustic and structural properties. However, the performance of the bricks frequently does not conform with the minimum legal requirements or the values required for high efficiency buildings, and for this reason, they need to be integrated with layers of thermal insulation. In this paper, the thermal behavior of hollow clay block with low emissivity treatment on the internal cavity surfaces has been investigated. The purpose of this application is to obtain a reduction in the thermal conductivity of the block by lowering the radiative heat exchange in the enclosures. The aims of this paper are to indicate a methodology for evaluating the thermal performance of the brick and to provide information about the benefits that should be obtained. Theoretical evaluations are carried out on several bricks (12 geometries simulated with two different thermal conductivities of the clay), using a finite elements model. The heat exchange procedure is implemented in accordance with the standard, so as to obtain standardized values of the thermal characteristics of the block. Several values of emissivity are hypothesized, related to different kinds of coating. Finally, the values of the thermal transmittance of walls built with the evaluated blocks have been calculated and compared. The results show how coating the internal surface of the cavity provides a reduction in the thermal conductivity of the block, of between 26% and 45%, for a surface emissivity of 0.1. Full article
(This article belongs to the Special Issue High Temperature Coatings)
Open AccessArticle Morphology and Microstructure of NiCoCrAlYRe Coatings after Thermal Aging and Growth of an Al2O3-Rich Oxide Scale
Coatings 2014, 4(4), 701-714; doi:10.3390/coatings4040701
Received: 14 July 2014 / Revised: 22 September 2014 / Accepted: 25 September 2014 / Published: 10 October 2014
PDF Full-text (6303 KB) | HTML Full-text | XML Full-text
Abstract
The surface of metal parts operating at high temperature in energy production and aerospace industry is typically exposed to thermal stresses and oxidation phenomena. To this aim, plasma spraying was employed to deposit NiCoCrAlYRe coatings on metal substrates. The effects of early-stage [...] Read more.
The surface of metal parts operating at high temperature in energy production and aerospace industry is typically exposed to thermal stresses and oxidation phenomena. To this aim, plasma spraying was employed to deposit NiCoCrAlYRe coatings on metal substrates. The effects of early-stage oxidation, at ~1100 °C, on their microstructure were investigated. The partial infiltration of oxygen through some open pores and microcracks embedded in coating microstructure locally assisted the formation of a stable Al2O3 scale at the splat boundary, while the diffusion of Cr and Ni and the following growth of Cr2O3, Ni(Cr,Al)2O4 and NiO were restricted to Al depleted isolated areas. At the same time, a continuous, dense and well adherent Al2O3 layer grew on the top-surface, and was somewhere supported by a thin mixed oxide scale mainly composed of Cr2O3 and spinels. Based on these results, the addition of Re to the NiCoCrAlY alloy is able to enhance the oxidation resistance. Full article
(This article belongs to the Special Issue High Temperature Coatings)
Open AccessArticle Thermal Conductivity Analysis and Lifetime Testing of Suspension Plasma-Sprayed Thermal Barrier Coatings
Coatings 2014, 4(3), 630-650; doi:10.3390/coatings4030630
Received: 20 July 2014 / Revised: 7 August 2014 / Accepted: 11 August 2014 / Published: 15 August 2014
Cited by 14 | PDF Full-text (1296 KB) | HTML Full-text | XML Full-text
Abstract
Suspension plasma spraying (SPS) has become an interesting method for the production of thermal barrier coatings for gas turbine components. The development of the SPS process has led to structures with segmented vertical cracks or column-like structures that can imitate strain-tolerant air [...] Read more.
Suspension plasma spraying (SPS) has become an interesting method for the production of thermal barrier coatings for gas turbine components. The development of the SPS process has led to structures with segmented vertical cracks or column-like structures that can imitate strain-tolerant air plasma spraying (APS) or electron beam physical vapor deposition (EB-PVD) coatings. Additionally, SPS coatings can have lower thermal conductivity than EB-PVD coatings, while also being easier to produce. The combination of similar or improved properties with a potential for lower production costs makes SPS of great interest to the gas turbine industry. This study compares a number of SPS thermal barrier coatings (TBCs) with vertical cracks or column-like structures with the reference of segmented APS coatings. The primary focus has been on lifetime testing of these new coating systems. Samples were tested in thermo-cyclic fatigue at temperatures of 1100 °C for 1 h cycles. Additional testing was performed to assess thermal shock performance and erosion resistance. Thermal conductivity was also assessed for samples in their as-sprayed state, and the microstructures were investigated using SEM. Full article
(This article belongs to the Special Issue High Temperature Coatings)
Figures

Open AccessArticle The Influence of Interface Characteristics on the Adhesion/Cohesion of Plasma Sprayed Tungsten Coatings
Coatings 2013, 3(2), 108-125; doi:10.3390/coatings3020108
Received: 3 May 2013 / Revised: 5 June 2013 / Accepted: 14 June 2013 / Published: 21 June 2013
Cited by 2 | PDF Full-text (5543 KB) | HTML Full-text | XML Full-text
Abstract
Tungsten is the prime candidate material for plasma facing components of future fusion devices. Plasma spraying, with its ability to coat large areas, including non-planar surfaces, with a significant thickness, is a prospective fabrication technology for components subject to moderate heat loads, [...] Read more.
Tungsten is the prime candidate material for plasma facing components of future fusion devices. Plasma spraying, with its ability to coat large areas, including non-planar surfaces, with a significant thickness, is a prospective fabrication technology for components subject to moderate heat loads, e.g., the first wall of the Demonstration Reactor (DEMO). The functionality of such coatings is critically dependent on their adhesion to the underlying material. This in turn, is influenced by a variety of processing-related factors, chief among them being the state of the interface. In this study, the effects of two factors—surface roughness and the presence of thin interlayers—were investigated. Two different levels of roughness of steel substrates were induced by grit blasting, and two thin interlayers—titanium (Ti) and tungsten (W)—were applied by physical vapor deposition prior to plasma spraying of W by a Water Stabilized Plasma (WSP) torch. Coating adhesion was determined by a shear adhesion test. The structures of the coatings and the interfaces, as well as the characteristics of the fractured surfaces, were observed by SEM. Full article
(This article belongs to the Special Issue High Temperature Coatings)

Review

Jump to: Research

Open AccessReview An Overview on Corrosion-Resistant Coating Technologies in Biomass/Waste-to-Energy Plants in Recent Decades
Coatings 2016, 6(3), 34; doi:10.3390/coatings6030034
Received: 10 June 2015 / Revised: 14 March 2016 / Accepted: 21 March 2016 / Published: 5 August 2016
PDF Full-text (19567 KB) | HTML Full-text | XML Full-text
Abstract
Highly efficient electric power generation from biomass/waste fuels becomes an important worldwide issue to prevent global warming. In these plants, severe high-temperature corrosion and erosion-corrosion damage occur in boiler tubes influenced by HCl, SOx gases, and chlorides as contaminants in fuels. [...] Read more.
Highly efficient electric power generation from biomass/waste fuels becomes an important worldwide issue to prevent global warming. In these plants, severe high-temperature corrosion and erosion-corrosion damage occur in boiler tubes influenced by HCl, SOx gases, and chlorides as contaminants in fuels. Coating technologies become important as a countermeasure for such damage, because of the easy maintenance, cost performance, and ease of application on various materials. In severe corrosive conditions of boilers, formation of dense, homogenous, and tough coating layers, as well as protective oxide layers of corrosion-resistant materials, are important. In the last 30 years, materials and coating processes applied in shop and on site have progressed based on many field observations and the consideration of deterioration mechanisms in order to maintain long lifetimes in the plants. Furthermore, new innovative coatings are now being developed by using advanced precise control, nanotechnologies, etc. This paper introduces recent trends of advanced coating developments and applications, such as weld-overlay, cladding, thermal spray coating, and slurry coating for biomass/waste boilers. Furthermore, the evaluation results of deterioration mechanisms and lifetime of coatings, and the future issue for innovative coatings, are presented. Full article
(This article belongs to the Special Issue High Temperature Coatings)

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