Papers by Author: Hui Tang

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Authors: Shan Shan Hao, Hui Tang, Wen Xue Wang
Abstract: Optical fiber preform is the core in the industry of optical fiber manufacturing, and vapor deposition is used in general internationally of which the raw material is expensive and the craft is complex. To reduce the cost of optical fiber,we selected tetraethoxysilane (TEOS) and H2O as raw material, ethanol as solvent, hydrochloric acid (HCl) and ammonia water as catalyst,in the condition of using different anti-cracking agent, including formamide (CH3NO), oxalic acid (C2H2O4), polyethyleneglycol 2000 (HO(C2H4O)nH), N, N-dimethyl formamide(C3H7NO) and glycerol(C3H8O3), to prepare SiO2 dry gel by sol-gel method in this paper. This paper mainly researched on the effect of anti-cracking agent on the cracking property of SiO2 dry gel. The XRD analysis indicated that the samples’ microstructures were amorphous. All kinds of anti-cracking agent were worked, but the effect on anti-cracking was different,and the dry gel which was added C3HNO was smooth and optimum, which were confirmed by the results of SEM. The analysis of the transmittance showed that the transmittance of dry gel with C3H8O3 was more than 92 percent.
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Authors: Y. Sha, Hui Tang, Jia Zhen Zhang
Abstract: In this paper, a detailed elastic-plastic finite element analysis of the effect of the compressive loading on crack tip plasticity is studied based on the material’s kinematic hardening model. Five centre-cracked panel specimens with different crack lengths are analyzed. The analysis shows that in a tension-compression loading the maximum spread of the crack tip reverse plastic zone increases with the increase of the compressive stress and the near crack tip opening displacement decreases with the increase of the compressive stress at the same nominal stress intensity factor. The applied compressive stress is the main factor controlling the near crack tip parameters.
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Authors: Shan Shan Hao, Wen Xue Wang, Hui Tang
Abstract: As carbon fiber reinforced silicon carbide composites combine the excellent mechanical properties of carbon fiber with good oxidation resistance of silicon carbide, considering material properties and economic cost, so much attention has been focused on short fiber reinforced ceramic matrix. but short carbon fiber is difficult to uniformly dispersed in the silicon carbide matrix, so how to disperse short carbon fibers in the matrix has become the key to prepare composite materials. In this article, through three processing methods to improve the dispersion, the three method are surface treatment of short carbon fibers, changing the mixed material ball milling time and adding a certain amount of SiC whisker. Results showed that the three processing methods all can improve the dispersion of short carbon fibers in silicon carbide matrix, but the dispersion effect also are different and the mechanism are different.the composites with better dispersion can achieved when carbon fibers which oxidized in concentrated nitric acid (68%) for 90minutes,and ball milling time was 48h and the concentration of SiC whisker was 5%.
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Authors: Yu Sha, Hui Tang, Xin Song, Jia Zhen Zhang
Abstract: In this paper, elastic-plastic finite element analysis has been performed in order to obtain the fatigue crack tip parameters under tension-compression loading. Two centre-cracked high-strength aluminum alloy with a crack length of 2mm under different tension-compression loading are analyzed. The analysis shows that the compressive loading has a significant contribution towards the crack tip plasticity and the crack tip stress. In a tension-compression loading the crack tip displacement increases with the increase of the compressive stress and the crack tip compress stress increases with the increase of the compressive stress. The maximum stress intensity Kmax in the tension part of the stress cycle and the maximum compressive stress in the compression part of the stress cycle are the main factors controlling the near crack tip parameters.
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Authors: Ji Peng Zhang, Hui Tang, Shan Shan Hao
Abstract: To reduce the cost of HDPE optical cable sheath, we selected HDPE as matrix materials, inorganic nanometer particles (CaCO3, SiO2) as modifier, prepared the modified HDPE optical cable sheath by mechanical blending method. The combination of CaCO3 particles with HDPE matrix was improved by titanate doped, which was able to facilitate the homogeneous dispersion of CaCO3 particles inside HDPE. To modify the optical cable sheath and reduce the product cost, the disparity of the inorganic nano-particle was analyzed, and the ratio of raw material and mixing technology were also improved. The experimental results indicated that: the sheathing compound with insulating characteristic as well as all technical indexes that reached its national standard, especially the toughening effect of the CaCO3, could be produced when CaCO3 content reached 7.5% and the volume resistivity was 104 times higher than the national standard. The mechanical modification of CaCO3 was better than SiO2.
385
Authors: Hui Tang, Yuan Zhao, Jin Zhong Zhang, Yu Sha, Li Guo Jin
Abstract: To prepare the amorphous SiO2 optical fiber preform which has lower attenuation, we selected TEOS as raw material, H2O as menstruum, HCl as catalyst, CH3NO as anti-cracking agent, prepared the mandrel material of SiO2 optical fiber preform by sol-gel method. The XRD, SEM, FT-IR and TG were used to study the characteristic of the samples. The results show that the TEOS and H2O can be uniformly mixed with vigorous stirring and water increasing. The hydrolysis rate of TEOS will increase with the increasing HCl volume. The transparency will decrease when the HCl reaches a fixed value. The CH3NO can play a role of anti-cracking agent, it also can affect the transparency if it is more. The optimal capability parameter TEOS: H2O: HCl: CH3NO = 1: 25: 0.5: 0.1. The optimal heat treatment process was determined by TG and FT-IR as follows: the temperature was risen slowly to 170°C and 300 °C for 1h, and then reluxed at 900°C for 2h.
368
Authors: Jun Peng Shao, Hui Tang, Yan Qin Zhang
Abstract: The surface material of Elastic-metal pads(EMP) is PTFE which has poor wearability . Ion implantation can improve the wearability of EMP surface .This paper investigated the wearability improvement of the EMP’s surface by Al2O3/PTFE film which generated by ion implantation. The accelerating voltage of the ion implantation apparatus is 40KV and the ion emitting energy of aluminum is 20KeV. The dosages of three kinds of Al3+ ion beams in the study are 1×1015 ions/cm2, 5×1015 ions/cm2 and 1×1016 ions/cm2 respectively. The aluminum ion’s density is 10uA/cm2. The vacuum pressure of the ion implantation is 3×10-3Pa. The experimental specimens modified by Al3+ ion implantation were tested by ESCA, XRD, AFM/FFM and nanometer probe , which got the chemical bond, phase structure and friction coefficient of the film. According to the experimental results, the mathematical model was built using the Fesow Geometric Model and the Halind Rang Theory. The computer simulation was made in which SRIM simulator program was employed. The ion implantation’s energy for the simulation is 20keV and the material density of PTFE is 2.56g/cm³. In addition, the dose is 5×1015 ions/cm², the time interval is 230 minutes and the velocity of Al3+ ion implantation is 2.15-2.20×1013 ions/minute. Finally the simulation curves of particle distribution, energy distribution and impairment etc. were plotted and discussed.
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Authors: Hui Tang, Ji Peng Zhang, Feng Gu, Feng Chun Wang, Ji Hua Wang
Abstract: SiO2 optical fiber preform, the parent material in manufacturing optical fiber, plays an important role in the properties of optical fiber. In this paper, SiO2 dry gel was prepared by Sol-Gel method. According to this method, the gel was formed by hydrolyzing tetraethyl orthosilicate(TEOS) with hydrochloric acid and ammonia water, and the SiO2 dry gel was obtained by heat treatment of the gel at different temperature. The structure of the dry gel as prepared was characterized by X-ray Diffraction(XRD), Fourier Transform Infrared Spectroscopy(FT-IR) and Scanning electron microscope(SEM). As a result, amorphous structure is proved. Meanwhile, microscopic cracks are found to be decreased by adding formamide and increased when the heat-treatment temperature is above 75°C.
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