Special Issue "Ultrahigh Temperature Ceramic Coatings and Composites"

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

Deadline for manuscript submissions: closed (31 May 2017).

Special Issue Editors

Guest Editor
Prof. Dr. Arvind Agarwal Website E-Mail
Department of Mechanical and Materials Engineering, Florida International University, Miami, FL, USA
Interests: consolidation and oxidation behavior of ultra high temperature ceramics; plasma spray; surface engineering; spark plasma sintering (SPS); nanomechanics and nanotribology; graphene and BN nanotube reinforced composites and coatings
Guest Editor
Prof. Dr. Kantesh Balani Website E-Mail
Department of Materials Science and Engineering, Indian Institute of Technology, Kanpur, India
Interests: ultrahigh temperature materials; biomaterials; energy materials; ab-initio modeling
Guest Editor
Dr. Cheng Zhang E-Mail
Department of Mechanical and Materials Engineering, Florida International University, Miami, FL, USA
Interests: ultra high temperature ceramics; plasma spray; spark plasma sintering (SPS)

Special Issue Information

Dear Colleagues,

We would like to invite you to submit your work to this Special Issue on “Ultrahigh Temperature Ceramic Coatings and Composites.” Extremely high melting points and outstanding mechanical and thermal properties allow Ultrahigh Temperature Ceramics (UHTCs) to be used as potential materials for use in the next generation of space transportation vehicles. The synthesizing methods, consolidation techniques as monoliths and coatings, oxidation behavior, and reusability of UHTCs require a thorough understanding and extensive studies. With the advances in sintering and in-situ characterization techniques, there is a renewed interest in studying UHTCs as composites and coatings. Oxidation behavior of UHTCs has largely been studied using isothermal furnace conditions; although these materials are supposed to be exposed to a much more aggressive dynamic gaseous environment. The modeling of the dynamic oxidation behavior of UHTCs has not been extensively studied. Hence, the topics of this Special Issues on UHTC coatings and composites include, but are not limited to:

•    New UHTCs materials systems (carbides, nitrides, diborides systems and their solid solutions or composites and coatings);
•    UHTC Synthesis techniques (powder, sintering and coating);
•    Advanced Characterization techniques (including in situ characterization);
•    Oxidation mechanisms at the extreme conditions including isothermal and dynamic conditions;
•    Computational and modeling studies on UHTCs.

 

Prof. Dr. Arvind Agarwal
Prof. Dr. Kantesh Balani
Dr. Cheng Zhang
Guest Editors

Manuscript Submission Information

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. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short 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 thoroughly refereed through a single-blind 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 monthly 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 1600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (6 papers)

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Research

Open AccessArticle
Thermal Analysis of Tantalum Carbide-Hafnium Carbide Solid Solutions from Room Temperature to 1400 °C
Coatings 2017, 7(8), 111; https://doi.org/10.3390/coatings7080111 - 28 Jul 2017
Cited by 5
Abstract
The thermogravimetric analysis on TaC, HfC, and their solid solutions has been carried out in air up to 1400 °C. Three solid solution compositions have been chosen: 80TaC-20 vol % HfC (T80H20), 50TaC-50 vol % HfC (T50H50), and 20TaC-80 vol % HfC (T20H80), [...] Read more.
The thermogravimetric analysis on TaC, HfC, and their solid solutions has been carried out in air up to 1400 °C. Three solid solution compositions have been chosen: 80TaC-20 vol % HfC (T80H20), 50TaC-50 vol % HfC (T50H50), and 20TaC-80 vol % HfC (T20H80), in addition to pure TaC and HfC. Solid solutions exhibit better oxidation resistance than the pure carbides. The onset of oxidation is delayed in solid solutions from 750 °C for pure TaC, to 940 °C for the T50H50 sample. Moreover, T50H50 samples display the highest resistance to oxidation with the retention of the initial carbides. The oxide scale formed on the T50H50 sample displays mechanical integrity to prevent the oxidation of the underlying carbide solid solution. The improved oxidation resistance of the solid solution is attributed to the reaction between Ta2O5 and HfC, which stabilizes the volume changes induced by the formation of Ta2O5 and diminishes the generation of gaseous products. Also, the formation of solid solutions disturbs the atomic arrangement inside the lattice, which delays the reaction between Ta and O. Both of these mechanisms lead to the improved oxidation resistances of TaC-HfC solid solutions. Full article
(This article belongs to the Special Issue Ultrahigh Temperature Ceramic Coatings and Composites)
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Open AccessArticle
Phase and Microstructural Correlation of Spark Plasma Sintered HfB2-ZrB2 Based Ultra-High Temperature Ceramic Composites
Coatings 2017, 7(8), 110; https://doi.org/10.3390/coatings7080110 - 26 Jul 2017
Cited by 8
Abstract
The refractory diborides (HfB2 and ZrB2) are considered as promising ultra-high temperature ceramic (UHTCs) where low damage tolerance limits their application for the thermal protection system in re-entry vehicles. In this regard, SiC and CNT have been synergistically added as [...] Read more.
The refractory diborides (HfB2 and ZrB2) are considered as promising ultra-high temperature ceramic (UHTCs) where low damage tolerance limits their application for the thermal protection system in re-entry vehicles. In this regard, SiC and CNT have been synergistically added as the sintering aids and toughening agents in the spark plasma sintered (SPS) HfB2-ZrB2 system. Herein, a novel equimolar composition of HfB2 and ZrB2 has shown to form a solid-solution which then allows compositional tailoring of mechanical properties (such as hardness, elastic modulus, and fracture toughness). The hardness of the processed composite is higher than the individual phase hardness up to 1.5 times, insinuating the synergy of SiC and CNT reinforcement in HfB2-ZrB2 composites. The enhanced fracture toughness of CNT reinforced composite (up to a 196% increment) surpassing that of the parent materials (ZrB2/HfB2-SiC) is attributed to the synergy of solid solution formation and enhanced densification (~99.5%). In addition, the reduction in the analytically quantified interfacial residual tensile stress with SiC and CNT reinforcements contribute to the enhancement in the fracture toughness of HfB2-ZrB2-SiC-CNT composites, mandatory for aerospace applications. Full article
(This article belongs to the Special Issue Ultrahigh Temperature Ceramic Coatings and Composites)
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Open AccessArticle
Chemical Vapor Deposition of TaC/SiC on Graphite Tube and Its Ablation and Microstructure Studies
Coatings 2017, 7(7), 101; https://doi.org/10.3390/coatings7070101 - 13 Jul 2017
Cited by 3
Abstract
Tantalum carbide (TaC) and silicon carbide (SiC) layers were deposited on a graphite tube using a chemical vapor deposition process. Tantalum chloride (TaCl5) was synthesized in situ by reacting tantalum chips with chlorine at 550 °C. TaC was deposited by reacting [...] Read more.
Tantalum carbide (TaC) and silicon carbide (SiC) layers were deposited on a graphite tube using a chemical vapor deposition process. Tantalum chloride (TaCl5) was synthesized in situ by reacting tantalum chips with chlorine at 550 °C. TaC was deposited by reacting TaCl5 with CH4 in the presence of H2 at 1050–1150 °C and 50–100 mbar. SiC was deposited at 1000 °C using methyl-tri-chloro-silane as a precursor at 50 mbar. At 1150 °C; the coating thickness was found to be about 600 μm, while at 1050 °C it was about 400 μm for the cumulative deposition time of 10 h. X-ray diffraction (XRD) and X-ray Photo-Electron Spectroscopy (XPS) studies confirmed the deposition of TaC and SiC and their phases. Ablation studies of the coated specimens were carried out under oxyacetylene flame up to 120 s. The coating was found to be intact without surface cracks and with negligible erosion. The oxide phase of TaC (TaO2 and Ta2O5) and the oxide phase of SiC (SiO2) were also found on the surface, which may have protected the substrate underneath from further oxidation. Full article
(This article belongs to the Special Issue Ultrahigh Temperature Ceramic Coatings and Composites)
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Open AccessArticle
Effect of Si3N4 Addition on Oxidation Resistance of ZrB2-SiC Composites
Coatings 2017, 7(7), 92; https://doi.org/10.3390/coatings7070092 - 30 Jun 2017
Cited by 3
Abstract
The oxidation behavior of ZrB2-20 vol % SiC and ZrB2-20 vol % SiC-5 vol % Si3N4 composites prepared by hot-pressing and subjected to isothermal exposure at 1200 or 1300 °C for durations of 24 or 100 [...] Read more.
The oxidation behavior of ZrB2-20 vol % SiC and ZrB2-20 vol % SiC-5 vol % Si3N4 composites prepared by hot-pressing and subjected to isothermal exposure at 1200 or 1300 °C for durations of 24 or 100 h in air, as well as cyclic exposure at 1300 °C for 24 h, have been investigated. The oxidation resistance of the ZrB2-20 vol % SiC composite has been found to improve by around 20%–25% with addition of 5 vol % Si3N4 during isothermal or cyclic exposures at 1200 or 1300 °C. This improvement in oxidation resistance has been attributed to the formation of higher amounts of SiO2 and Si2N2O, as well as a greater amount of continuity in the oxide scale, because these phases assist in closing the pores and lower the severity of cracking by exhibiting self-healing type behavior. For both the composites, the mass changes are found to be higher during cyclic exposure at 1300 °C by about 2 times compared to that under isothermal conditions. Full article
(This article belongs to the Special Issue Ultrahigh Temperature Ceramic Coatings and Composites)
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Open AccessArticle
Oxidation Behavior and Mechanism of Al4SiC4 in MgO-C-Al4SiC4 System
Coatings 2017, 7(7), 85; https://doi.org/10.3390/coatings7070085 - 23 Jun 2017
Cited by 4
Abstract
Al4SiC4 powder with high purity was synthesized using the powder mixture of aluminum (Al), silicon (Si), and carbon (C) at 1800 °C in argon. Their oxidation behavior and mechanism in a MgO-C-Al4SiC4 system was investigated at 1400–1600 [...] Read more.
Al4SiC4 powder with high purity was synthesized using the powder mixture of aluminum (Al), silicon (Si), and carbon (C) at 1800 °C in argon. Their oxidation behavior and mechanism in a MgO-C-Al4SiC4 system was investigated at 1400–1600 °C. XRD, SEM, and energy dispersive spectrometry (EDS) were adopted to analyze the microstructure and phase evolution. The results showed that the composition of oxidation products was closely related to the atom diffusion velocity and the compound oxide layer was generated on Al4SiC4 surface. In addition, the effect of different CO partial pressure on the oxidation of Al4SiC4 crystals was also studied by thermodynamic calculation. This work proves the great potential of Al4SiC4 in improving the MgO-C materials. Full article
(This article belongs to the Special Issue Ultrahigh Temperature Ceramic Coatings and Composites)
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Open AccessArticle
Combustion Synthesis of UHTC Composites from Ti–B4C Solid State Reaction with Addition of VIb Transition Metals
Coatings 2017, 7(6), 73; https://doi.org/10.3390/coatings7060073 - 01 Jun 2017
Abstract
UHTC composites were prepared by self-propagating high-temperature synthesis (SHS) from the Ti–B4C reaction system with addition of Cr, Mo, and W. The starting sample composition was formulated as (3−x)Ti + B4C + xMe with x = [...] Read more.
UHTC composites were prepared by self-propagating high-temperature synthesis (SHS) from the Ti–B4C reaction system with addition of Cr, Mo, and W. The starting sample composition was formulated as (3−x)Ti + B4C + xMe with x = 0.1–1.0 and Me = Cr, Mo, or W. For all samples conducted in this study, self-sustaining combustion was well established and propagated with a distinct reaction front. With no addition of Cr, Mo, or W, solid state combustion of the 3Ti + B4C sample featuring a combustion front temperature (Tc) of 1766 °C and a combustion wave velocity (Vf) of 16.5 mm/s was highly exothermic and produced an in situ composite of 2TiB2 + TiC. When Cr, Mo, or W was adopted to replace a portion of Ti, the reaction exothermicity was lowered, and hence, a significant decrease in Tc (from 1720 to 1390 °C) and Vf (from 16.1 to 3.9 mm/s) was observed. With addition of Cr, Mo, and W, the final products were CrB-, MoB-, and WB-added TiB2–TiC composites. The absence of CrB2, MoB2, and WB2 was attributed partly to the loss of boron from thermal decomposition of B4C and partly to lack of sufficient reaction time inherent to the SHS process. Full article
(This article belongs to the Special Issue Ultrahigh Temperature Ceramic Coatings and Composites)
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