Simulation and experiment study of burrs in micro-milling Zr-based metallic glass

Jiachun Wang,Zhenhong Zhang,Chuang Zhang,Jiabin Fu,Jianchao Chen 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.7

Metallic glass has been widely used in making micro parts and equipment due to its excellent physical and chemical performance. A large quantity of burrs is produced in the micro-milling process that is hard to remove and seriously affects the quality and precision of the parts. Burrs should be effectively restrained; however, the burrs’ type, position and the effect of milling parameters on burrs’ generation in micro-milling metallic glass have not been systematically studied. In this paper, by using 3-D FEM simulation and taking micro-milling experiments of Zr-based metallic glass (Vit1), the burrs in flat-end milling and ball-end milling micro grooves were investigated. The burrs’ type and position were observed and summarized, the formation process of various burrs was analyzed in detail, and the influence of cutting parameters on burrs was clarified. Comparing the simulation and experiment result, we could confirm that the top burr and the entrance burr were produced during the processing of the flatend milling cutter, and ball-end milling cutter effectively inhibits the production of the top burr but takes no actions on burrs’ generation at the entrance and the bottom of the groove. The main cause of the top burr is the extrusion of the tool, and the extrusion of the cutting layer metal and chip accumulation were the main reason for entrance and exit burrs. Reducing the axial cutting depth could effectively restrain the generation of burrs for both two kinds of milling tools.

Fabrication and Characterization of Titanate Nanotube Supported ZSM-5 Zeolite Composite Catalyst for Ethanol Dehydration to Ethylene

Liangpeng Wu,Xinjun Li,Zhenhong Yuan,Yong Chen 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.2

Titanium dioxide nanotube supported ZSM-5 zeolite composite catalyst was fabricated by decorating ZSM-5 zeolite on the hydrothermally synthesized titanium dioxide via hydrothermal process and subsequent annealing. The catalyst was characterized by X-ray powder diffraction (XRD), Transmission electron microscopy (TEM) and Nitrogen adsorption-desorption (BET). The surface acidity of the catalyst was measured by means of Fourier transform infrared (FT-IR) spectrum of pyridine adsorption. And the catalytic activity for ethanol dehydration to ethylene was evaluated in a continuous flow fixed-bed reactor. Attributed to the increase of the effective surface acid sites caused by titanium dioxide nanotube as electron acceptor, titanium dioxide nanotube supported ZSM-5 zeolite composite catalyst exhibits strongly enhanced activity for ethanol dehydration to ethylene.

Three-Dimensional Porous Carbon Nanotube Papers as Current Collector and Buffer for SnO2 Anodes

Xiaogang Sun,Zhiwen Qiu,Long Chen,Manyuan Cai,Jie Wang,Xu Li,Wei Chen,Zhenhong Liu,Hao Tang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.11

A novel three-dimensional porous conductive papers have been successfully synthesized via a simple physical route. Multi-walled carbon nanotubes (MWCNTs)@SnO2 composite anode materials are embedded in porous conductive papers. The peculiar structure can accommodate the huge volume expansion of MWCNTs@SnO2 composite anode materials during charge–discharge process. The framework formed by MWCNTs and cellulose can greatly improve the strength, stability and flexibility of the electrode. In addition, the structure successfully prevent the aggregation of SnO2 nanoparticles and collapse of MWCNTs@SnO2 composite electrode, leading to the improvement in electrochemical utilization and stable cyclability. The samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), respectively. The electrochemical properties and application were evaluated by galvanostatic discharge–charge testing and cycling voltammetry. As a result, the MWCNTs@SnO2 composite electrode showed excellent rate performance. The discharge capacity remains about 680mAh g -1 after 100 cycles at 200mA g -1, and even around 300mAh g -1 at 1000mA g -1.

Fabrication and Characterization of Titanate Nanotube Supported ZSM-5 Zeolite Composite Catalyst for Ethanol Dehydration to Ethylene

Wu, Liangpeng,Li, Xinjun,Yuan, Zhenhong,Chen, Yong Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.2

Titanium dioxide nanotube supported ZSM-5 zeolite composite catalyst was fabricated by decorating ZSM-5 zeolite on the hydrothermally synthesized titanium dioxide via hydrothermal process and subsequent annealing. The catalyst was characterized by X-ray powder diffraction (XRD), Transmission electron microscopy (TEM) and Nitrogen adsorption-desorption (BET). The surface acidity of the catalyst was measured by means of Fourier transform infrared (FT-IR) spectrum of pyridine adsorption. And the catalytic activity for ethanol dehydration to ethylene was evaluated in a continuous flow fixed-bed reactor. Attributed to the increase of the effective surface acid sites caused by titanium dioxide nanotube as electron acceptor, titanium dioxide nanotube supported ZSM-5 zeolite composite catalyst exhibits strongly enhanced activity for ethanol dehydration to ethylene.

Electrochemical Performance of Lithium-Ion Capacitors Using Pre-Lithiated Multiwalled Carbon Nanotubes as Anode

Manyuan Cai,Xiaogang Sun,Yanyan Nie,Wei Chen,Zhiwen Qiu,Long Chen,Zhenhong Liu,Hao Tang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.4

Pre-lithiated multiwalled carbon nanotube anode was prepared by internal short circuit approach (ISC) for 5 min, 30 min, 60 min and 120 min respectively. Lithium ion capacitors (LICs) were assembled by using pre-lithiated multiwalled carbon nanotubes as anodes and activated carbon (AC) as cathodes. The structure of multiwalled carbon nanotubes and electrodes were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical performance of pre-lithiated multiwalled carbon nanotube electrodes and pristine carbon nanotube electrodes were tested by galvanostatic charge/discharge and electrochemical impedance. The results indicated that pre-lithiation carbon nanotubes greatly improved the charge/discharge performance of LICs. The energy density was four times than conventional electric double-layer capacitors (EDLCs) at the current density of 100 mA/g. The LICs achieved a specific capacitance of 59.3 F/g at the current density of 100 mA/g with 60 min pre-lithiatiation process. The maximum energy density and power density was 96Wh/kg and 4035W/kg, respectively. The energy density still remained about 89.0% after 1000 cycles. The LIC showed excellent supercapacitor performance.

Genetic variation of Vp1 in Sichuan wheat accessions and its association with pre-harvest sprouting response

Jirui Wang,Yaxi Liu,Yan Wang,Zhenhong Chen,Shuai Dai,Wenguang Cao,George Fedak,Xiujing Lan,Yuming Wei,Dengcai Liu,Youliang Zheng 한국유전학회 2011 Genes & Genomics Vol.33 No.2

Pre-harvest sprouting (PHS) in bread wheat is a major abiotic constraint reducing yield and influencing the production of high quality grain. In China both spring and winter wheat regions are affected by PHS. Sichuan lies in southwest China,where the most of rainfall occurs during April to September when wheat is harvested. The present investigation was conducted to identify the allelic variability of Vp1, a gene that plays a role in maintenance and induction of dormancy,among Sichuan landraces and recent cultivars with different dormancy levels and to find potential sources of PHS resistance for breeding. Sichuan landrace and cultivar wheat accessions had a wide range of dormancy levels. The average germination index (GI) of Sichuan landrace accessions was 0.232, whereas at 0.674 it was much higher for cultivars. The different dormancy levels between landraces and cultivars indicated that pre-harvest sprouting resistance might have been neglected in recent Sichuan wheat breeding programs. The average GI of white grained accessions was higher than for red grained accessions. Particular Vp-1B gene fragments were specific in landraces or cultivars and in white or red grained accessions. The results indicated that Vp-1B markers could be used to distinguish cultivars and landraces. Significant relationships between certain Vp-1B allelesand GI of Sichuan wheat accessions were shown by Spearman’s rank correlation analysis.