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2023 Vol. 53, No. 10

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2023-10 Contents
2023, 53(10): 1-2.
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2023-10 Abstract
2023, 53(10): 1-2.
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Engineering & Materials
Thermophysical properties of 1D materials: transient characterization down to atomic level
Amin Karamati, Shen Xu, Huan Lin, Mahya Rahbar, Xinwei Wang
2023, 53(10): 1001. doi: 10.52396/JUSTC-2023-0098
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The thermophysical properties of 1D micro/nanoscale materials could differ significantly from those of their bulk counterparts due to intensive energy carrier scattering by structures. This work provides an in-depth review of cutting-edge techniques employed for transient characterization of thermophysical properties at the micro/nanoscale scale. In terms of transient excitation, step Joule heating, step laser heating, pulsed laser heating, and frequency domain amplitude-modulated laser heating are covered. For thermal probing, electrical and Raman scattering-based physical principles are used. These techniques enable the measurement of thermal conductivity, thermal diffusivity, and specific heat from the sub-mm level down to the atomic level (single-atom thickness). This review emphasizes the advantages of these techniques over steady state techniques and their physics, challenges, and potential applications, highlighting their significance in unraveling the intricate thermal transport phenomena to the atomic level of 1D materials.
Synthesis, properties, and applications of topological quantum materials
Junjie Wu, Ying Zhang, Bin Xiang
2023, 53(10): 1002. doi: 10.52396/JUSTC-2023-0024
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Since topological quantum materials may possess interesting properties and promote the application of electronic devices, the search for new topological quantum materials has become the focus and frontier of condensed matter physics. Currently, it has been found that there are two interesting systems in topological quantum materials: topological superconducting materials and topological magnetic materials. Although research on these materials has made rapid progress, a systematic review of their synthesis, properties, and applications, particularly their synthesis, is still lacking. In this paper, we emphasize the experimental preparation of two typical topological quantum materials and then briefly introduce their potential physical properties and applications. Finally, we provide insights into current and future issues in the study of topological quantum material systems.
Design of novel double-layer wrapped ammonium polyphosphate and its application in aging-resistant and flame retardant crosslinked polyethylene composites
Pengfei Jia, Pengfei Sun, Fuhao Yu, Lei Song, Yuan Hu, Bibo Wang
2023, 53(10): 1003. doi: 10.52396/JUSTC-2023-0090
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In this study, double-layer wrapped ammonium polyphosphate (APP) is designed to enhance the mechanical properties, resistance and flame retardancy of crosslinked polyethylene (XLPE) composites. APP was wrapped with silica and then grafted with hindered phenol antioxidant 3-(3,5-di-tert-butyl-4 hydroxyphenyl) (AO) to prepare double-layer wrapped flame retardants (MCAPP). Due to the excellent compatibility between the MCAPP and XLPE matrix, the tensile strength and elongation at break of XLPE/MCAPP/CFA (XLPE-4) were improved. Moreover, the retention rate of elongation at break for the XLPE-4 composite reached 61.1%, significantly higher than that of XLPE-1 (2.6%) at 135 °C after aging for 14 d. This demonstrates that MCAPP could improve the aging resistance of XLPE cable composites. Compared with XLPE-1, the maximum smoke density and the peak heat release rate were reduced by 54.9% and 89.7%, respectively. Thus, the double-layer wrapping antioxidant strategy provides an excellent approach to obtain high-performance XLPE composites.
Effects of residual stress caused by abrasion on the flexoelectric response of BaTiO3 ceramics
Xu Yang, Dongxia Tian, Xiaoyan Zhang, Ruzhong Zuo, Baojin Chu
2023, 53(10): 1004. doi: 10.52396/JUSTC-2023-0015
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The spontaneously polarized surface layer, which originates from stress relaxation, has been proposed for the unexpectedly large flexoelectric response measured in ferroelectric ceramics. However, the source of the stress that led to the polarized surface layer is still not completely known. In this work, the effect of surface stress on the microstructure, dielectric properties and flexoelectric response of BaTiO3 ceramics abraded by abrasive papers of various grit sizes was systematically studied. Compared with the as-prepared sample, the flexoelectric coefficients of abraded BaTiO3 ceramics decreased from ~600 μC/m to less than 200 μC/m. The flexoelectric coefficients of all the samples, however, recovered to ~500 μC/m following heat treatment at 200 °C and a subsequent slow cooling process. The results indicate that abrasion can introduce stress on the surface layers and affect the flexoelectric response of ferroelectric ceramics to some extent, but the stress is not the main reason for the formation of polarized surface layers.
Assessment study of different radiation models in the simulation of 1 m methanol pool fire
Qianjun Zhou, Yong Hu, Yong Jiang
2023, 53(10): 1005. doi: 10.52396/JUSTC-2023-0021
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Pool fires are one of the most commonly encountered flame types in fire disasters, and the accurate and detailed modeling of pool fires is beneficial for the hazard analysis and assessment of liquid-related fire accidents. The radiation model is known to be the critical component in the accurate simulation of various fire scenarios. Therefore, to develop a proper radiation model, an LES study of a large-scale methanol pool fire was performed in this work by coupling four different radiation models into the open-source fire simulation code FDS and solving the radiation intensity transport equation using the discrete ordinates method. The impact characteristics of different radiation models are evaluated in detail with the NIST experiments, where the comparative analysis was carried out. Regarding the temperature calculations, the WSGG (weighted-sum-of-gray-gases)-based radiation model and Cassol’s model performed better. In addition, all models predict pulsation frequencies well. However, regarding the prediction of the radiative heat fluxes, Cassol’s two models and the FDS default model outperformed the other models, which indicates that the database for obtaining the spectral information of each species and the method to determine the WSGG coefficient of mixed gases are significant factors for the successful prediction of flame radiation.
Predicting vapor-liquid equilibria of CO2+HFC binary mixtures by the PR EOS combined with a group contribution model
Zirui Wu, Lingfeng Shi, Rui Sun, Hua Tian, Xuan Wang, Gequn Shu
2023, 53(10): 1006. doi: 10.52396/JUSTC-2023-0001
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CO2+HFC binary mixtures have good performance and environmental friendliness and are considered good alternative working fluids in cooling and power cycle systems. The vapor-liquid phase equilibrium properties are key to the calculation of the enthalpy and entropy of mixtures, which is critical for the analysis of cooling and power cycle systems. To accurately predict the vapor-liquid equilibrium of CO2 and HFC (R23, R32, R41, R125, R134a, R143a, R152a, R161, and R227ea) binary mixtures, a group contribution model based on the excess free energy (GE) mixing rules (PR+MHV1+UNIFAC and PR+LCVM+UNIFAC) is established in this paper. The interaction parameters between groups such as -CO2, -Alkane, -CHF, and -CHF3 are obtained by the vapor-liquid phase equilibrium experiment of CO2 and HFC refrigerants, and these group parameters are critical for predicting their vapor-liquid phase equilibrium properties (the pressures and vapor phase molar fractions). The AARDp value calculated by the PR+LCVM+UNIFAC model is 5.53%, the value of AADy1 is 0.0132, and the AARDp and AADy1 values of the PR+MHV1+UNIFAC model are 7.40% and 0.0229, respectively. However, for the CO2+R32 system, the PR+MHV+UNIFAC prediction model can reproduce the experimental data with lower deviations, and the values of AARDp and AADy1 are 1.53% and 0.0045, respectively. In summary, for CO2+HFC binary mixtures, the PR+LCVM+UNIFAC group contribution model can reproduce the experimental data with lower deviations, but for individual CO2 binary mixtures (such as CO2+R32), the PR+MHV1+UNIFAC model also has unique advantages. According to the prediction results of the group contribution model, the PR+LCVM+UNIFAC model has significantly improved the calculation progress compared with the PR+MHV1+UNIFAC model used in the previous system.

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