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722 results on '"Liu, Jiangwen"'

40. Improving the precision of micro-EDM for blind holes in titanium alloy by fixed reference axial compensation

Author

Lin Chaohui, Li Jiaming, Liang Shiyong, Zhang Yonghui, Gou Junfeng, Liu Jiangwen, and Li Yao

Subjects
edm, titanium alloy, frac method, depth deviation, roundness factor, Technology, Chemical technology, TP1-1185
Abstract

During the electrical discharge machining (EDM) process, the tool electrode wear is inevitable, which affects the process precision of the micro-hole. In the present experimental investigation, a fixed reference axial compensation (FRAC) method is proposed to enhance the machining precision of micro-hole. The effect of pulse power, compensation methods, and electrode materials on the depth and roundness factor of micro-hole are explored. The experiment results show that the FRAC method can realize the accurate compensation and reach the expected depth hole processing. When the FRAC is used, the depth deviation is less than 0.43%, and the minimum difference from the expected depth is only 0.106 µm. In addition, the micro-holes of tungsten steel and brass electrodes machine by the FRAC method were close to the expected depth, the difference from the expected depth less than 0.7%, but the bottom of micro-hole produced a cone. However, compared to tungsten steel and brass electrodes, the copper electrode has a better processing performance, the roundness factor is up to 79.8%. When the long-pulse power supply is applied, the expected depth of 400–1,600 µm blind holes with a better processing shape, and the phenomenon of the cone at the bottom are not apparent. Therefore, the proposed FRAC method can be utilized in many high-end manufacturing fields to improve the precision of the micro-hole for micro features.

Published
2021
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48. Compositional tuning of A2B7-type La0.7–xYxMg0.3Ni3.5alloys for gaseous hydrogen storage

Author

Du, Junkun, Wang, Hui, Tang, Renheng, Liu, Jiangwen, Ouyang, Liuzhang, and Zhu, Min

Abstract

Rare earth-based superlattice alloys have great potential for gaseous hydrogen storage, as well as successful application as nickel-metal hydride batteries anodes. In this work, Y substitution was carried out to adjust the gaseous hydrogen storage properties of A2B7-type La0.7Mg0.3Ni3.5alloys. The results indicate a multiphase structure in the alloys comprised of the main rhombohedral Gd2Co7and PuNi3phases, with a small amount of CaCu5phase. Moreover, the Y substitution results in higher abundance of the Gd2Co7phase. The alloy La0.42Y0.28Mg0.3Ni3.5exhibits a hydrogen storage capacity of 1.55 wt% at 298 K and a desorption plateau pressure of 0.244 MPa. In addition, this alloy demonstrates a stable cycle life by a capacity retention of 94.2% after 50 cycles, with the main capacity degradation occurring during the initial 20 cycles. This work accentuates the potential of the La–Y–Mg–Ni-based superlattice alloys for applications in solid-state hydrogen storage.

Published
2024
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50. Process Optimization and Physicochemical Characterization of Solid-state Fermentation of Summer-autumn Tea by Eurotium cristatum.

Author

ZHENG Xuandong, XU Shanshan, LIU Jiangwen, SUN Lei, WU Xuefeng, MU Dongdong, CHEN Xiangsong, and LI Xingjiang

Subjects
SOLID-state fermentation, GAS chromatography/Mass spectrometry (GC-MS), PROCESS optimization, FLAVONOIDS, AMINO acids
Abstract

To improve the quality of summer-autumn tea, the fermentation of summer-autumn tea was investigated by using Eurotium cristatum. The contents of tea polyphenols, total free amino acids, total flavonoids, water leachate, and sensory scores of summer-autumn tea were used as the indicators for the one-way experiment, and four factors and three levels were selected for orthogonal experiments to optimize the fermentation process. The volatile compounds of fermented summer-autumn tea under the optimal process were analyzed by gas chromatography-mass spectrometry (GC-MS) technology. The results showed that the optimal fermentation process was 30% water content, 15% inoculum of Eurotium cristatum, fermentation time of 9 d, and fermentation temperature of 30 °C, and the water leachate content of summer-autumn tea processed under these conditions was significantly increased by 22.51% (P<0.05), the tea polyphenol content was significantly decreased by 27.71% (P<0.05), and the total flavonoid content was significantly decreased by 6.41% (P<0.01), free amino acids did not change significantly, and the sensory score was significantly improved by 10.33 points (P<0.01). In addition, the total amount of flavor compounds was elevated by 296.76% after fermentation, and the content of linalool, linalool oxide I, α-Terpineol, methyl salicylate, and phenethyl acetate substances increased especially significantly throughout the fermentation process, which brought rich fruity and floral aroma to the summer-autumn tea. Thus, the overall quality of summer-autumn tea improved after fermentation treatment. [ABSTRACT FROM AUTHOR]

Published
2024
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