Strengthening, Corrosion and Protection of Superalloys and Ultrahigh Temperature Ceramics

A special issue of Coatings (ISSN 2079-6412). This special issue belongs to the section "Corrosion, Wear and Erosion".

Deadline for manuscript submissions: closed (30 November 2023) | Viewed by 4366

Special Issue Editor


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Guest Editor
School of Metallurgical Engineering, Anhui University of Technology, Maanshan, China
Interests: refractory metals and their alloys; porous ceramics; silicide ceramics; ultrahigh-temperature ceramics; surface coating technology; corrosion and protection; high-temperature oxidation; slag erosion; oxidation mechanism; failure mechanism; second-phase enhancement; analysis of and solutions to corrosion- and protection-related problems
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Special Issue Information

Dear Colleagues,

Superalloys and ultrahigh-temperature ceramics have a high melting point, high strength and high-temperature creep resistance, a low thermal expansion coefficient and good corrosion resistance. They are widely used in metallurgical, chemical, aerospace, nuclear reactor and other extreme environments. During high-temperature services, superalloys and ultrahigh-temperature ceramics are exposed to extremely harsh high-temperature environments and must endure mechanical and thermal loads, high temperature oxidation, erosion, corrosion, etc. Therefore, high stress is concentrated at the defect site, especially near the phase interface; this thermal expansion stress drives the nucleation and propagation of cracks. At the same time, friction, oxidation and corrosion aggravate crack propagation and material failure, which pose a catastrophic threat to high-temperature components. Therefore, the characterization, understanding and strengthening and corrosion protection of superalloys and ultrahigh temperature ceramics are critical. This Special Issue focuses on second-phase enhancement, surface coating technology, high-temperature corrosion, wear, erosion and protection in superalloys and ultrahigh-temperature ceramics.

The corrosion of superalloys and ultrahigh-temperature ceramics remains a major technological and economical challenge as the service life and stability of metal and ceramic components are often affected by environmental corrosion. During high-temperature services, superalloys and ultrahigh-temperature ceramics are exposed to extremely harsh high-temperature environments and must endure mechanical and thermal loads, high-temperature oxidation, erosion, corrosion, etc. Therefore, the characterization, understanding and strengthening and corrosion protection of superalloys and ultrahigh-temperature ceramics are critical.  Original research articles and reviews are welcome. Research areas may include (but are not limited to) the following:

  • Corrosion protection;
  • Corrosion mechanisms;
  • Corrosion resistance;
  • High-temperature oxidation;
  • High-temperature corrosion;
  • Mechanical corrosion;
  • Friction wear corrosion;
  • Chemical corrosion;
  • Surface and coating technology;
  • Surface modification and covering treatment;
  • Mechanisms and methods of corrosion control.

Dr. Yingyi Zhang
Guest Editor

Manuscript Submission Information

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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 2600 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.

Keywords

  • metals
  • ceramic
  • alloys
  • refractory metals
  • surface modification
  • coating
  • corrosion protection
  • high-temperature oxidation
  • friction and wear

Published Papers (3 papers)

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Research

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20 pages, 3757 KiB  
Article
Microstructure and Melting Loss Behavior of Blast Furnace Incoming Coke and Radial Tuyere Coke
by Hongliang Wu, Laihao Yu, Shengchao Chang, Yingyi Zhang and Jialong Yang
Coatings 2022, 12(8), 1172; https://doi.org/10.3390/coatings12081172 - 13 Aug 2022
Cited by 2 | Viewed by 1283
Abstract
As an indispensable raw material in blast furnace ironmaking, coke plays an important role, which is also the key to low-carbon smelting and reducing ironmaking carbon emissions, so it is necessary to study its quality, degradation behavior, and microstructure evolution. In this work, [...] Read more.
As an indispensable raw material in blast furnace ironmaking, coke plays an important role, which is also the key to low-carbon smelting and reducing ironmaking carbon emissions, so it is necessary to study its quality, degradation behavior, and microstructure evolution. In this work, the pore structure and micromorphology of the blast furnace incoming coke (IC) and tuyere coke (TC) were analyzed comprehensively by comparative research methods. The results showed that the microcrystalline structure of TC was more orderly than that of IC. In addition, the order degree of the coke microcrystalline structure increased first and then decreased in the radial direction and reached the highest value at the distance of 1–2 m from the tuyere. The porosity of radial TC increased obviously. The pore wall became thinner, and the pore size of the original micropores in TC expanded. Simultaneously, large numbers of micropores were also generated, and cracks appeared, resulting in the specific surface area and pore volume of TC becoming higher than that of IC. Moreover, the graphite structure inside TC increased, and the crystal structure became larger. In the radial direction, with an increase in temperature, the number of amorphous structures in coke decreased, the ordering increased, and the graphite structure continued to grow. However, along the direction of the furnace core, a decrease in temperature led to the stagnation of amorphous structure content and a decrease in graphitization degree. Full article
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14 pages, 3796 KiB  
Article
Microstructure Evolution Behavior of Blast-Furnace Coke under Different Gasification Reaction Conditions
by Hongliang Wu, Laihao Yu, Shengchao Chang, Yingyi Zhang and Jialong Yang
Coatings 2022, 12(8), 1116; https://doi.org/10.3390/coatings12081116 - 04 Aug 2022
Cited by 4 | Viewed by 1342
Abstract
With the development of large-scale blast-furnace and oxygen-rich coal-injection technology, as well as national green and low-carbon policy requirements, the ironmaking process has increasingly strict requirements for blast-furnace raw materials, such as new and higher requirements for coke quality and thermal performance. In [...] Read more.
With the development of large-scale blast-furnace and oxygen-rich coal-injection technology, as well as national green and low-carbon policy requirements, the ironmaking process has increasingly strict requirements for blast-furnace raw materials, such as new and higher requirements for coke quality and thermal performance. In this study, the melting loss reaction in a blast furnace was simulated under laboratory conditions and the microstructure evolution of coke after melting loss under CO2 and CO2 + H2O conditions was studied. The results showed that under a CO2 atmosphere, the specific surface area and pore volume of coke and the number of micropores in coke first increased and then decreased with the increase in reaction time, while the average pore size first decreased from 17.289 to 8.641 nm and then increased to 9.607 nm. In the gasification reaction between CO2 and coke, the relative content of the graphitized structure (IG/IAll) increased first, then decreased and then increased with the increase in reaction time, while the change trends of disordered structure (ID3/IG) and unstable structure (ID4/IG) were opposite to IG/IAll, indicating that coke still tended to be more orderly with the increase in time. In the mixed atmosphere of CO2 and H2O, the specific surface area and IG/IAll of coke increased with the increase in H2O content. However, when the proportion of H2O exceeded 50%, the specific surface area decreased slightly, and the pore-size value corresponding to the peak value in the pore-size distribution curve shifted to the right, and the average pore-size increased in the nanosize range. Full article
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22 pages, 9702 KiB  
Essay
Effect of Salt Bath Nitriding and Reoxidation Composite Texture on Frictional Properties of Valve Steel 4Cr10Si2Mo
by Yifan Dai, Zefei Tan, Wengang Chen, Dongyang Li, Jubang Zhang, Zexiao Wang, Yukun Mao, Yuhao Wang and Wenxuan Guo
Coatings 2023, 13(4), 776; https://doi.org/10.3390/coatings13040776 - 17 Apr 2023
Cited by 1 | Viewed by 1195
Abstract
In order to improve the service life of 4Cr10Si2Mo valve steel, laser processing technology was used to prepare triangular textures with different area occupancies on the surface of 4Cr10Si2Mo, and then 4Cr10Si2Mo was subjected to salt bath nitridation (salt bath temperature 580 °C) [...] Read more.
In order to improve the service life of 4Cr10Si2Mo valve steel, laser processing technology was used to prepare triangular textures with different area occupancies on the surface of 4Cr10Si2Mo, and then 4Cr10Si2Mo was subjected to salt bath nitridation (salt bath temperature 580 °C) and oxidation (oxidation temperature 400 °C). The mechanism of composite surface treatment technology on friction and wear performance of valve steel was explored. The effect of triangular texture on working surface stress and hydrodynamic pressure was explored using simulation technology, and the mechanism of texture in friction was further studied. The XRD test results showed that after salt bath nitriding and reoxidation treatment, the surface of 4Cr10Si2Mo mainly contained Fe2N oxide film and Fe3O4 and other components. The XPS test showed that the nitriding layer contained Cr-N, and the surface hardness reached 710.5 HV0.5. The simulation results showed that introducing surface texture will increase the stress on the contact surface, especially near the texture. However, under lubricating conditions, the flow field in the textured lumen produces a wedge effect, which increases the oil film pressure. After salt bath nitriding composite texture treatment, the wear resistance of 4Cr10Si2Mo significantly improved under the synergistic effect of the nitrided layer dominated by the magnetite phase (Fe3O4) and the microtexture. Fe3O4 can reduce the friction coefficient and resist oxidation reactions. In addition, the texture of the area occupancy of the texture also affects the surface tribological properties. The texture with an area occupancy rate of 11.45% (low × high is 0.3 mm × 0.3 mm) had the best anti-friction effect, and the friction coefficient reduced by 65%. Full article
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