High-Temperature Materials

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Issue 2, Volume 2 – 6 articles

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TiO2 and polyarylene ether nitrile (PEN) hybrids (TiO2-PEN) with high-temperature dielectric energy storage properties were fabricated through self-crosslinking of phthalonitrile groups from phthalonitriles modified TiO2 (TiO2-2CN) and phthalonitriles terminated PEN (PEN-2CN). The formation of covalent bonds within TiO2-PEN hybrids enhances the thermal and dielectric energy storage performances, offering promising applications in high-temperature electronic power systems. For the TiO2-PEN hybrid with 10 wt% filler, its glass transition temperature is increased to 218 °C, the discharged energy density at 150 °C is over 95% of that at room temperature, the discharged energy efficiency is higher than 90% and remains unchanged even after 10,000 cycling measurements at 150 °C. 
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Open Access

Review

14 April 2025

Advancements in Flexible Ceramic Fibers for High-Temperature Applications: A Comprehensive Review

Flexible ceramic fibers (FCFs) have emerged as a highly promising material for high-temperature applications, effectively combining the excellent thermal stability of ceramic materials with the robust mechanical properties of flexible fibers. This review provides a comprehensive overview of recent advances in multifunctional FCF devices, focusing on innovative methods across material selection, structural design, and fabrication techniques to enhance their functional properties. These improvements, i.e., mechanical strength, thermal conductivity, and oxidation resistance, make FCFs particularly suitable for a wide range of applications, including energy storage, sensing, and high-temperature filtration. Notably, advancements in fabrication techniques have enabled the creation of novel FCF devices for thermal insulation and high-temperature sensing, such as stretchable ceramic membranes and printable ceramic fiber papers. The review concludes by discussing the future potential of FCFs, especially in multifunctional applications in high-temperature environments, where they can serve as essential components of advanced technologies. This work highlights the versatility and potential of FCFs as a transformative material for next-generation high-temperature applications.

Zijian Xu
Ying Lyu
Chao Hou
Yanqi Han
Yunzhao Bai
YongAn Huang*
Kan Li*
High-Temp. Mat.
2025,
2
(2), 10007; 
DOI: 10.70322/htm.2025.10007
Open Access

Communication

19 May 2025

Preparation of High-Temperature Resistant Hydrophilic Membrane for Oil-Water Separation

Through the molecular structure design, first starting from the molecular structure of the monomer, the monomer of the synthetic structure continues to polymerize with propanesulfonolactone, and finally reacts with quaternary ammonium salts to obtain polyimide containing biswitterionic groups. In this study, a hydrophilic polyimide membrane with a quaternary ammonium salt structure was synthesized. Then, the sulfonate hydrophilic structure was introduced into the polyimide film by electrospinning and the stencil method. Hydrophilic groups were introduced by introducing propane sulfonate, and the PI membrane was prepared by electrospinning and the template method. The results show that introduced sulfonic acid groups reduce the contact angle of polyimide membrane from 85° to 30°. The water permeability, porosity and mechanical strength of the membrane were tested and analyzed, and the membrane showed excellent oil-water separation performance.

Xue Fang
Yang Wang*
Kan Kan
Yuliang Ma
Shumeng Zhou
Xiaochen Zhang
High-Temp. Mat.
2025,
2
(2), 10008; 
DOI: 10.70322/htm.2025.10008
Open Access

Article

06 June 2025

Effects of Changing the Specific Surface Area in the Ceramic Matrix of CAC-Containing Refractory Castables on the Initial Stiffening and Setting Behaviour

Besides the coarse and medium grain size distribution, the matrix components play a central role in the performance of refractory castables. Practical experience shows that the particle size distribution (PSD) and the specific surface area of the ceramic matrix significantly influence processing, setting, and sintering behaviour. However, there is a lack of systematic studies on how PSD or specific surface area changes affect castable properties. This study aims to address this gap by varying ceramic matrices to create refractory model castables with different matrix surface areas. Three dispersing agents with different mechanisms (electrosteric and steric) were used at graded concentrations. Results show that castables with higher specific surface areas (using (very) finely ground and highly sintered alumina raw materials with high specific surface areas) and different dispersing agents and their concentrations show substantial differences in the initial stiffening and setting behaviour. Higher specific surface areas of the matrix result in an earlier first stiffening, while adding more dispersing agents leads to delayed stiffening. The refractory model castables’ first stiffening and hydration range (with a simultaneous temperature maximum) vary considerably depending on the dispersing agent used and its concentration, caused by completely different mechanisms.

Florian Holleyn*
Tim Waldstädt
Johannes Kasper
Christian Dannert
Olaf Krause
High-Temp. Mat.
2025,
2
(2), 10009; 
DOI: 10.70322/htm.2025.10009
Open Access

Article

09 June 2025

High-Temperature Dielectric Energy Storage Materials Fabricated by Crosslinking Titanium Dioxide and Polyarylene Ether Nitrile

Dielectric materials have broad application prospects in the field of high-temperature electronic power systems. Up to now, high-temperature dielectric materials are mainly prepared by using high glass transition temperature (Tg) polymers. However, the incompatibility between polymers and fillers, which are incorporated for high energy density, leads to soaring dielectric losses at high temperatures, resulting in a nosedive of discharged energy density (Ud) and efficiency (η). In this paper, we report the fabrication of high-temperature dielectric materials via the self-crosslinking of phthalonitriles from phthalonitriles modified titanium dioxide (TiO2-2CN) and phthalonitriles terminated polyarylene ether nitrile (PEN-2CN). TiO2-2CN is firstly synthesized and characterized, then incorporated into PEN-2CN to prepare TiO2/PEN nanocomposites, which transform into TiO2-PEN hybrids afterwards. The fabricated TiO2-PEN hybrids are confirmed by the change of SEM sectional morphology, as well as the increase of their Tg and thermal decomposition temperature (Td). With the addition of TiO2-2CN, both the Tg, Td, and Ud of TiO2/PEN nanocomposites are improved. In addition, due to the formation of covalent bonds within TiO2-PEN, the hybrids exhibit excellent high-temperature dielectric energy storage performance. Specifically, at 150 °C, the Ud of 10 wt% TiO2-PEN is 0.60 J/cm−3, which is over 95% of that at RT. Moreover, η is greater than 90% and remains unchanged after 10,000 charge and discharge cycles. This method used for preparing TiO2-PEN hybrids through a self-crosslinking reaction of phthalonitriles provides a new approach for preparing high-temperature dielectric materials.

Yujie Feng
Shumin Bao
Zaixing Wang
Yongxian Liu
Yayao Jiao
Lingling Wang*
Xiufu Hua*
Renbo Wei*
High-Temp. Mat.
2025,
2
(2), 10010; 
DOI: 10.70322/htm.2025.10010
Open Access

Review

11 June 2025

Recent Advances in High-Temperature Properties of High-Entropy Alloys

High-temperature alloys are critical for advanced thermal components in aerospace and energy industries. Conventional alloys, which rely on a single principal element with limited alloying additions, often exhibit insufficient phase stability and rapid oxidation at extreme temperatures. In recent years, high-entropy alloys (HEAs) have emerged as revolutionary candidates for high-temperature applications, overcoming the limitations of conventional alloys through their unique multi-principal element design and exceptional performance. This review systematically examines the latest progress in HEAs’ key high-temperature properties: tensile properties, creep resistance, oxidation resistance, and phase stability. Research demonstrates that HEAs achieve remarkable mechanical properties at elevated temperatures through multiple mechanisms, such as lattice distortion effects, precipitation of ordered L12-structured phases, and refined grain boundary engineering. For instance, refractory HEAs like MoNbTaVW and Hf-Nb-Ti-V systems exhibit superior creep resistance at temperatures exceeding 1600 °C, outperforming traditional nickel-based superalloys. The slow diffusion of oxygen and the formation of multi-component oxide layers enhance the high-temperature oxidation resistance of high-entropy alloys. Additionally, HEAs display excellent phase stability under thermal exposure, driven by high configurational entropy and optimized microstructural designs, including nanoscale lamellar phases and coherent precipitates. Despite these advances, challenges remain in balancing mechanical strength with ductility, ensuring long-term durability under cyclic thermal-mechanical loads, and tailoring compositions for extreme service conditions. Future efforts should integrate machine learning, computational modeling, and high-throughput experiments to accelerate the discovery of novel HEA systems and validate their performance in practical applications. By addressing these challenges, HEAs are poised to revolutionize material solutions for next-generation aerospace engines, nuclear reactors, and high-efficiency energy systems.

Weiming Pan
Daoyuan Huang
Wanlin Wang
Guangyang Dou
Peisheng Lyu*
High-Temp. Mat.
2025,
2
(2), 10011; 
DOI: 10.70322/htm.2025.10011
Open Access

Article

11 June 2025

Effect of Post Rolling Strategies on Microstructure and Mechanical Properties of Martensitic Heat-Resistant Steel

Four different rolling strategies were applied to comparatively study the post-rolling process on the microstructure and high-temperature mechanical properties of a high-boron P92 martensitic heat-resistant steel. Both the characteristics of martensitic lath structures and the evolution of precipitation and texture states are illustrated. Their influence on mechanical properties was also discussed based on the recrystallization state, dislocation density, precipitation state, and also the activation tendency of slipping systems of the dominated texture component. Results revealed that the post-rolling process can significantly improve the plasticity of quenched P92 steel while leading to the reduction of strength simultaneously. However, a high reduction and post isothermal holding sample (HRH) shows the best high-temperature mechanical performance with a balanced tensile strength of 352 MPa and elongation of 33.6%. It is the enhanced precipitation strengthening, recrystallization refinement, and lower Schmid values of main texture components that contribute to the mechanical property improvement of the HRH sample.

Fan Fei
Qing Guo
Cong Cao
Lei Cheng*
Wei Yu
High-Temp. Mat.
2025,
2
(2), 10012; 
DOI: 10.70322/htm.2025.10012
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