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- 저자 : Xiufang He (검색결과 3 건)
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Wide-Gap Repair of Mar-M247 Superalloy via Powder Metallurgy Route
Xiufang Gong,Yankang Yu,Tianjian Wang,Ye Liu,Lin Zhang,Zhenhuan Gao,Hou Ziyong,Xu Chen,Shuang He,Xuanhui Qu 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.11
Wide-gap defects repair of Mar-M247 superalloy was investigated by utilizing powder metallurgy. New interlayer alloy withrelatively high content of B and Zr was designed based on the isothermal solidification principle. The interlayer alloy ischaracterized by relative low melting temperature (1100 °C), and the contact angle of interlayer on the Mar-M247 substrateis ~ 70º. Based on the thermodynamic calculation results, the mixture powders with 80 wt% substrate powder and 20 wt%interlayer alloy powder was used as a filler to repair the wide gap with width of 2 mm. After repaired at 1230 °C for 2 h, nearfullydense gap was obtained. MC-type carbides, MB2-type boride, M3B2-type boride and Ni5(Zr,Hf)-type intermetallic wereobserved in the liquid zone. After post-weld heat treatment, the block borides, chain carbides and eutectic are successfullyremoved, and the tensile strength of the bonding zone is close to that of the Mar-M247 superalloy.
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Zhonghai Sun,Zhansheng Wu,Dandan Liu,Xiufang He 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.2
Polycyclic aromatic hydrocarbons (PAHs) are toxic pollutants harmful to humans. To improve the adsorption capacity of PAHs on activated carbon (AC) from the aqueous system, AC was modified with cationic surfactants through microwave heating. Naphthalene is a typical PAH used as a model pollutant to test the adsorption properties of sample; the sample with the best adsorption performance was named SAC. The SAC was characterized by SEM, FTIR and BET in detail compared with AC. The specific surface area and the average pore size of SAC increased by nearly 100m2 g−1 and 0.14 nm more than the original AC, respectively. The adsorption experiment was carried out by batch technique with variables such as contact time, adsorbent amount, pH and temperature. Results showed that naphthalene was adsorbed rapidly during the first 20min, and thereafter reached adsorption equilibrium in 40 min. The adsorption kinetics of naphthalene on SAC can be well described by the pseudo-second-order model and the Freundlich isotherm model better fitted the adsorption isotherms of naphthalene on SAC. Naphthalene adsorption process on SAC was spontaneous and temperature was found to negatively affect the adsorption capacity. Furthermore, film diffusion was confirmed the rate limiting step. The π-π stacking electron donor acceptor interaction, hydrophobic interaction and hydrogen bonding may play more key roles in naphthalene adsorption on SAC than AC. Thus, microwave- assisted surfactants modification was proven to be an effective method to enhance the adsorption of naphthalene onto SAC from aqueous solution.
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Design of a Two Stage Low Noise System in the Frequency Band 1.8-2.2GHz for Wireless System
Zhao Xiaorong,Fan Honghui,Ye Feiyue,Qian Xiufang,Chen Dan,He Sheng 보안공학연구지원센터 2015 International Journal of Future Generation Communi Vol.8 No.3
In first stage of each microwave receiver there is Low Noise Amplifier (LNA) circuit, and this stage has important rule in quality factor of the receiver. This paper presents the design of LNA and development of low bias (VD=3V, ID=20mA), the LNA operating in frequency range 1.8-2.2GHz using a feedback circuit. Design System (ADS) 2012 tool was used for design and simulation, and each design was tuned to get the optimum value for NF, power gain (S21), input return loss (S11) and reverse isolation (S12). Simulation results have indicated that the S21 achieves 33.2515±0.4475dB over the wide frequency band of 1.8-2.2 GHz, the gain was almost flat over the whole band. Noise figure (NF) maintains is 0.4945±0.0565 dB, S12 < -47.089 dB and S11 < -16.126 dB in the entire band.
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