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327 results on '"Shi, Baolu"'

105. An experimental study on arcing in arc-enhanced plasma machining technology for etching of silicon carbide ceramics

Author

Lin Zhou, Yifan Dai, Shi Baolu, Xuhui Xie, and Shengyi Li

Subjects
010302 applied physics, 0209 industrial biotechnology, Materials science, Plasma etching, Mechanical Engineering, 02 engineering and technology, 01 natural sciences, Industrial and Manufacturing Engineering, Computer Science Applications, Electric arc, chemistry.chemical_compound, 020901 industrial engineering & automation, Machining, chemistry, Control and Systems Engineering, visual_art, 0103 physical sciences, visual_art.visual_art_medium, Silicon carbide, Ceramic, Composite material, Reactive-ion etching, Inductively coupled plasma, Plasma processing, Software
Abstract

Atmosphere plasma etching methods have been applied to the machining of optics. However, due to the high chemical stability and inertness of silicon carbide (SiC) ceramics, it seems difficult to improve the material removal rate (MRR) for conventional etching methods. We have found MRR will be significantly improved while arc forms between the inductively coupled plasma and SiC ceramic surface. This etching method is called arc-enhanced plasma machining (AEPM) technology. Arc-enhanced plasma (AEP) is represented as the secondary of a high-frequency transformer considering capacitive coupling in this paper. Radio frequency (RF) voltage in AEP is measured. The RF voltage of plasma is extremely high to form arc when plasma is close to the SiC ceramic surface. The measurement results of RF voltage at the metal-plasma interface show that the arc formation is related to the distance between source jet and workpiece (Dj-w). When Dj-w is small, a nonconductive layer of cooled argon forms over the workpiece surface, preventing arcing. Trenches are etched on SiC ceramic surface with different Dj-w, finding that the MRR is improved under the arcing action and the optimal Dj-w is obtained.

Published
2016

106. Arc-Enhanced Plasma Machining Technology for High Efficiency Machining of Silicon Carbide

Author

Lin Zhou, Shengyi Li, Xuhui Xie, Yifan Dai, and Shi Baolu

Subjects
010302 applied physics, Figuring, Plasma etching, Materials science, business.industry, Plasma parameters, General Chemical Engineering, 02 engineering and technology, General Chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Surfaces, Coatings and Films, chemistry.chemical_compound, chemistry, Etching (microfabrication), 0103 physical sciences, Electric spark, Silicon carbide, Optoelectronics, Inductively coupled plasma, Reactive-ion etching, 0210 nano-technology, business
Abstract

Atmosphere plasma etching methods have been demonstrated efficient in the etching of fused silica or ULE. However, because of the high chemical stability of silicon carbide (SiC), the conventional plasma etching methods seem incapable of obtaining a high material removal rate (MRR). We have found that MRR will be significantly improved while the electric spark appears between the plasma and the SiC surface. As a result, a new plasma source is designed to generate stable arc at the surface. Due to the generation of arc, the MRR of 0.35 mm3/min is obtained, about 10 times as high as the conventional method. In this paper, the removal characteristics and the thermal effect of this method are presented. MRR and the surface temperature are investigated in dependence on plasma parameters: RF power, travel speed of plasma source, SF6 gas flow and O2 gas flow. Due to the negligible thermal effect, the surface figuring can be achieved using the conventional dwell time method. The shape error of a flat SiC surface is corrected, verifying the figuring capability and the effectiveness of this method.

Published
2016

117. MORC2B is essential for meiotic progression and fertility

Author

Shi, Baolu, primary, Xue, Jiangyang, additional, Zhou, Jian, additional, Kasowitz, Seth D., additional, Zhang, Yuanwei, additional, Liang, Guanxiang, additional, Guan, Yongjuan, additional, Shi, Qinghua, additional, Liu, Mingxi, additional, Sha, Jiahao, additional, Huang, Xiaoyan, additional, and Wang, P. Jeremy, additional

Published
2018
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126. Effect of 3D Printing Parameters on Interlayer Adhesive Properties of Printed Parts.

Author

Yu Hong, Yang Mengru, Wu You, Yao Jingjing, Shi Baolu, Li Xiaoqiang, and Hu Jing

Subjects
THERMOPLASTICS, FUSED deposition modeling, POLYLACTIC acid, THERMOPLASTICS manufacturing, MEASUREMENT of tensile strength, SCANNING electron microscopes
Abstract

A series of standard tensile and impact test bars were prepared via fused deposition modeling on a desktop 3D printer, and the effects of the printing parameters (including nozzle temperature, print height, et al), annealing or not, and the type of printing materials on the interlayer adhesion of printed part were investigated. The ABS and PLA samples presented an enhancement in tensile strength and elongation with increasing nozzle temperature, and however they were reduced with increasing layer height. SEM observation demonstrated that, with an increase of print height, the interfacial porosity of ABS and PLA samples was improved but their bonding area in wire decreased. The residual stress of ABS sample was removed by annealing, leading to an improvement in tensile strength and toughness. The crimp-cracking phenomenon became serious for PLA sample, followed by a decrease in tensile strength and toughness. [ABSTRACT FROM AUTHOR]

Published
2018
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127. Ignition and Oxidation of Core–Shell Al/Al2O3Nanoparticles in an Oxygen Atmosphere: Insights from Molecular Dynamics Simulation

Author

Chu, Qingzhao, Shi, Baolu, Liao, Lijuan, Luo, Kai H., Wang, Ningfei, and Huang, Chenguang

Abstract

This study employed the reactive force field molecular dynamics to capture atomic-level heat and mass transfer and reaction processes of an aluminum nanoparticle (ANP) oxidizing in a high temperature and pressure oxygen atmosphere, revealing detailed mechanisms for oxidation of ANPs. Temporal variations of temperature, density, mean square displacement, atom consumption rate, and heat release rate of ANPs have been systematically examined. In addition, the effects of environment on ANP oxidation were also evaluated. The results show that ANPs undergo four stages of preheating, melting, fast Al core, and moderate shell oxidations during the whole oxidation process. The Al core starts to melt from a core–shell interface with outward diffusion of core Al atoms into the shell. Intense reaction occurs between shell O and core Al atoms around the interface at the end of melting, leading to fast Al core oxidation. After complete oxidation of the Al core, the oxide shell continues to react with ambient O atoms. Both the initial environmental temperature and the equivalent pressure significantly influence the preheating. Conversely, the melting stage seems almost independent of any of them. However, fast Al core oxidation presents more sensitivity to the ambient equivalent pressure.

Published
2018
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140. Micro-aluminum powder with bi- or tri-component alloy coating as a promising catalyst: Boosting pyrolysis and combustion of ammonium perchlorate

Author

Wang, Chao, Liu, Ying, Wu, Mingze, Li, Jia, Feng, Ying, Ning, Xianjin, Li, Hong, Wang, Ningfei, and Shi, Baolu

Abstract

A novel design of micro-aluminum (μAl) powder coated with bi-/tri-component alloy layer, such as: Ni–P and Ni–P–Cu (namely, Al@Ni–P, Al@Ni–P–Cu, respectively), as combustion catalysts, were introduced to release its huge energy inside Al-core and promote rapid pyrolysis of ammonium perchlorate (AP) at a lower temperature in aluminized propellants. The microstructure of Al@Ni–P–Cu demonstrates that a three-layer Ni–P–Cu shell, with the thickness of ∼100 nm, is uniformly supported by μAl carrier (fuel unit), which has an amorphous surface with a thickness of ∼2.3 nm (catalytic unit). The peak temperature of AP with the addition of Al@Ni–P–Cu (3.5%) could significantly drop to 316.2 °C at high-temperature thermal decomposition, reduced by 124.3 °C, in comparison to that of pure AP with 440.5 °C. It illustrated that the introduction of Al@Ni–P–Cu could weaken or even eliminate the obstacle of AP pyrolysis due to its reduction of activation energy with 118.28 kJ/mol. The laser ignition results showed that the ignition delay time of Al@Ni–P–Cu/AP mixture with 78 ms in air is shorter than that of Al@Ni–P/AP (118 ms), decreased by 33.90%. Those astonishing breakthroughs were attributed to the synergistic effects of adequate active sites on amorphous surface and oxidation exothermic reactions (7597.7 J/g) of Al@Ni–P–Cu, resulting in accelerated mass and/or heat transfer rate to catalyze AP pyrolysis and combustion. Moreover, it is believed to provide an alternative Al-based combustion catalyst for propellant designer, to promote the development the propellants toward a higher energy.

Published
2023
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149. Effect of flat-wall impingement on diesel spray combustion.

Author

Li, Kuichun, Nishida, Keiya, Ogata, Youichi, and Shi, Baolu

Subjects
DIESEL motor combustion, CHEMILUMINESCENCE, PYROMETRY
Abstract

The effect of spray–flat-wall interaction on the diesel combustion characteristics in a constant-volume vessel was investigated. A flat wall was fixed perpendicular to the nozzle hole axis. Three injection pressures of 100 MPa, 150 MPa and 200 MPa and a single nozzle hole with a diameter of 0.133 mm were employed. Mie scattering was adopted to detect the spray formation process; OH* chemiluminescence and natural colour luminosity were conducted to analyse the combustion process. The two-colour method was applied to calculate the soot emissions and the temperature distribution. The results reveal that, in comparison with a free spray flame, flat-wall impingement causes diesel combustion to deteriorate when the liquid phase–wall interaction occurs; however, when an appropriate impinging distance (longer than liquid-phase penetration) is selected, combustion is observed to be enhanced. As for the impinging spray flame, when the injection pressure is increased, soot formation decreases; however, combustion is not linearly enhanced by increasing the injection pressure, and the OH* chemiluminescence intensity achieves the highest value with an injection pressure of 150 MPa. [ABSTRACT FROM PUBLISHER]

Published
2015
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