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290 results on '"He, Dingyong"'

58. Preparation and characterization of (Yb0.25Lu0.25Sc0.25Tm0.25)2Si2O7 as a potential environmental barrier coating.

Author

Wang, Peng, He, Dingyong, Guo, Xingye, Zhou, Zheng, Shao, Wei, Wu, Yang, and Wang, Guohong

Abstract

A novel high‐entropy rare‐earth disilicate (Yb0.25Lu0.25Sc0.25Tm0.25)2Si2O7 ((4RE0.25)2Si2O7) was proposed as an advanced environmental barrier coating (EBC) materials in this work. The (4RE0.25)2Si2O7 powders were synthesized using the solid‐state sintering method. Based on the X‐ray diffraction (XRD) and scanning electron microscope/energy‐dispersive spectroscopy analysis, the uniform solid solution was detected in the (4RE0.25)2Si2O7, which had a monoclinic β‐phase structure in the space group of C2/m. The lattice parameter of the structure was derived based on the Rietveld refinement analysis to the XRD results. The coefficient of thermal expansion of the bulk (4RE0.25)2Si2O7 was similar to that of the SiC‐SiC ceramic matrix composite substrate of the environmental barrier coating. In addition, this (4RE0.25)2Si2O7 bulk material had a very low thermal conductivity, which was beneficial for the application of environmental barrier coatings. The hot water‐vapor corrosive experiments were conducted in an environment of 90% air and 10% H2O at 1300°C. The results indicated a better water‐vapor corrosion performance than the commercialized Yb2Si2O7 EBC materials. The (4RE0.25)2Si2O7 material prepared in this work showed great potential to work as the environmental barrier coating. [ABSTRACT FROM AUTHOR]

Published
2024
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59. Acceleration Mechanism of Steel Slag Hydration Using THEED.

Author

Yue, Deyu, Wang, Jianfeng, Huo, Pengchen, Chang, Lei, He, Dingyong, Cui, Suping, and Liu, Hui

Subjects
SLAG, HYDRATION kinetics, POROSITY, STEEL, COMPRESSIVE strength
Abstract

In this paper, the strength development of a pure steel slag (SS) system with various concentrations of N,N,N′,N′-Tetrakis-(2-hydroxyethyl) ethylenediamine (THEED) was investigated. The hydration kinetics, pore structure and microstructure of SS pastes with and without THEED were characterized to underscore the working mechanism of THEED. Results show that THEED additions significantly increase the 3, 7 and 28 days compressive strength of hardened SS pastes. The enhancement effect increases with the dosage of THEED. At a concentration of 2000 ppm, THEED increased the compressive strength by 733%, 665%, and 545% at 3, 7 and 28 days, respectively. It is confirmed that THEED additions improve the hydration degree of SS by accelerating hydration of the aluminum phase (C3A, PDF-38-1429; C12A7, PDF-48-1882) and C2F,(PDF 38-0408) to generate Mc (PDF-41-0219) and Pa (PDF-30-0222) in the presence of CaCO3. Also, the hydration degree of silicates is increased by THEED. In this way, THEED additions refine the pore structure of hardened SS paste by increasing the pore volume with a diameter below 300 nm to achieve enhancement. The chelating effect of THEED results in promoting dissolution of SS, which provides the driving force for accelerating SS hydration. [ABSTRACT FROM AUTHOR]

Published
2024
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