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2,973 results on '"Wang, Hongjie"'

113. Synthesis of MAX Phases Nb2CuC and Ti2(Al0.1Cu0.9)N by A-site Replacement Reaction in Molten Salts

Author

Ding, Haoming, Li, Youbing, Lu, Jun, Luo, Kan, Chen, Ke, Li, Mian, Persson, Per O. A., Hultman, Lars, Eklund, Per, Du, Shiyu, Huang, Zhengren, Chai, Zhifang, Wang, Hongjie, Huang, Ping, and Huang, Qing

Subjects
Condensed Matter - Materials Science
Abstract

New MAX phases Ti2(AlxCu1-x)N and Nb2CuC were synthesized by A-site replacement by reacting Ti2AlN and Nb2AlC, respectively, with CuCl2 or CuI molten salt. X-ray diffraction, scanning electron microscopy, and atomically-resolved scanning transmission electron microscopy showed complete A-site replacement in Nb2AlC, which lead to formation of Nb2CuC. However, the replacement of Al in Ti2AlN phase was only close to complete at Ti2(Al0.1Cu0.9)N. Density-functional theory calculations corroborated the structural stability of Nb2CuC and Ti2CuN phases. Moreover, the calculated cleavage energy in these Cu-containing MAX phases are weaker than in their Al-containing counterparts, indicating that they are precursor candidates for MXene derivation., Comment: author name corrected

Published
2019

123. Anisotropic and hierarchical SiC@SiO2 nanowire aerogel with exceptional stiffness and stability for thermal superinsulation

Author

Su, Lei, Wang, Hongjie, Niu, Min, Dai, Sheng, Cai, Zhixin, Yang, Biguo, Huyan, Huaixun, and Pan, Xiaoqing

Subjects
Macromolecular and Materials Chemistry, Engineering, Chemical Sciences, Affordable and Clean Energy
Abstract

Ceramic aerogels are promising lightweight and high-efficient thermal insulators for applications in buildings, industry, and aerospace vehicles but are usually limited by their brittleness and structural collapse at high temperatures. In recent years, fabricating nanostructure-based ultralight materials has been proved to be an effective way to realize the resilience of ceramic aerogels. However, the randomly distributed macroscale pores in these architectures usually lead to low stiffness and reduced thermal insulation performance. Here, to overcome these obstacles, a SiC@SiO2 nanowire aerogel with a nanowire-assembled anisotropic and hierarchical microstructure was prepared by using directional freeze casting and subsequent heat treatment. The aerogel exhibits an ultralow thermal conductivity of ~14 mW/m·K, an exceptional high stiffness (a specific modulus of ~24.7 kN·m/kg), and excellent thermal and chemical stabilities even under heating at 1200°C by a butane blow torch, which makes it an ideal thermally superinsulating material for applications under extreme conditions.

Published
2020

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