Effects of surface texturing on nanotribological properties and subsurface damage of monocrystalline GaN subjected to scratching investigated using molecular dynamics simulation
作者：
Guo, Jian;Chen, Jingjing* ;Lin, Yunzhi;Liu, Zemeng;Wang, Yongqiang*
期刊：
Applied Surface Science ,2021年539:148277 ISSN：0169-4332
通讯作者：
Wang, Yongqiang;Chen, Jingjing
作者机构：
[Guo, Jian; Liu, Zemeng; Lin, Yunzhi; Wang, Yongqiang] Univ South China, Sch Mech Engn, Hengyang 421001, Hunan, Peoples R China.;[Chen, Jingjing] Nanjing Univ Aeronaut & Astronaut, Nanjing 210016, Jiangsu, Peoples R China.;[Chen, Jingjing] Ningde Normal Univ, Sch Informat & Elect Engn, Ningde 352100, Fujian, Peoples R China.
通讯机构：
[Wang, Yongqiang] U;[Chen, Jingjing] N;Univ South China, Sch Mech Engn, Hengyang 421001, Hunan, Peoples R China.;Nanjing Univ Aeronaut & Astronaut, Nanjing 210016, Jiangsu, Peoples R China.
关键词：
GaN;MD simulation;Nano-texture;Nanotribological properties;Subsurface damage
摘要：
Surface nanotribological properties and subsurface damage of flat and textured gallium nitride (GaN) substrates during both linear and circular nanoscratching processes are investigated using molecular dynamics simulation. Results show that the surface texture can remarkably reduce not only the surface friction and wear but also the scratching-induced subsurface damage regardless of the tip radius and penetration depth. Tangential force and friction coefficient decreased with an increase in groove width or depth primarily due to the reduced contact area. The effect of texturing on stress distribution can affect the development of dislocation to alleviate the nanoscale material deformation and removal and thereby reduce surface wear and subsurface damage. Increasing tip radius can reduce the friction coefficient and surface wear, but it promotes subsurface damage. By contrast, increasing tip penetration depth can increase the friction, wear, and subsurface damage for flat and textured GaN substrates. Compared with the c-plane, the m-plane GaN substrate exhibits higher friction but lower material wear, and it has a considerably thicker subsurface damage layer due to the difference in their dislocation networks. This work can provide useful insights into the design of GaN-based material with antifriction and wear properties through the surface texturing treatments. © 2020 Elsevier B.V.
语种：
英文
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Effect of abrasive size on nano abrasive machining for wurtzite GaN single crystal via molecular dynamics study
作者：
Wang, Yongqiang;Guo, Jian*
期刊：
Materials Science in Semiconductor Processing ,2021年121:105439 ISSN：1369-8001
通讯作者：
Guo, Jian
作者机构：
[Guo, Jian; Wang, Yongqiang] Univ South China, Sch Mech Engn, Hengyang 421001, Hunan, Peoples R China.
通讯机构：
[Guo, Jian] U;Univ South China, Sch Mech Engn, Hengyang 421001, Hunan, Peoples R China.
关键词：
GaN single Crystal;Nano abrasive machining;Abrasive size;Molecular dynamics
摘要：
Molecular dynamics simulations were used to explore the effect of abrasive size on the nano abrasive machining for wurtzite gallium nitride (GaN) single crystal. The deformation behaviours, varied with the abrasive size, were systematically analysed. The simulation results show that increasing the abrasive size results in more severe plastic deformation and machining-induced hardening, which consequently cause an increase in atomic tem-perature, strain, stress, and cutting forces. The use of larger abrasive produces greater compression, thus boosts the elastic recovery and damages the subsurface of GaN single crystal much heavily, with the enhancement of the nucleation and emission of dislocation, and the local phase transition from B4 to B3 structure or even to fivefold hexagonal structure. The development of pile-up and amorphization is impressively inhibited by increasing abrasive size, suggesting that the cutting effect could be impaired using a larger abrasive under a given depth of cut.
语种：
英文
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Molecular dynamics study on deformation behaviour of monocrystalline GaN during nano abrasive machining
作者：
Wang, Yongqiang;Tang, Sai;Guo, Jian*
期刊：
Applied Surface Science ,2020年510:145492 ISSN：0169-4332
通讯作者：
Guo, Jian
作者机构：
[Guo, Jian; Tang, Sai; Wang, Yongqiang] Univ South China, Sch Mech Engn, Hengyang 421001, Hunan, Peoples R China.
通讯机构：
[Guo, Jian] U;Univ South China, Sch Mech Engn, Hengyang 421001, Hunan, Peoples R China.
关键词：
Deformation;GaN;Molecular dynamics;Nano abrasive machining
摘要：
Molecular dynamics simulations are carried out to investigate the nano abrasive machining of monocrystalline gallium nitride (GaN). Effects of the cutting velocity, depth of cut (DOC) and abrasive shape on the atomic strain, stress, temperature, cutting forces, and deformation layer are systematically investigated, aiming at understanding the deformation behaviour of monocrystalline GaN during nano abrasive machining. The results show that the strain, stress and temperature were increased by using the higher cutting velocity, the larger DOC or cub-octahedral abrasive. Being affected by both the average stress and the elasto-plastic deformation zone right ahead the diamond particle, the cutting forces increase with the increase in DOC but decrease under a larger cutting velocity, or when using a cub-octahedral abrasive. The deformation layer in the subsurface is insensitive to the cutting velocity, while impressively shrinks under a larger DOC or cub-octahedral abrasive used. As the stress and temperature rise, the use of higher cutting velocity, larger DOC or cub-octahedral abrasive would facilitate the nucleation of dislocation, phase transition and the development of pile-up. This work can enrich the understanding on the nanoscale deformation mechanism of monocrystalline GaN material during the ultra-precision machining process. © 2020 Elsevier B.V.
语种：
英文
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Temperature effect on mechanical response of c-plane monocrystalline gallium nitride in nanoindentation: A molecular dynamics study
作者：
Guo, Jian;Chen, Jingjing;Wang, Yongqiang*
期刊：
Ceramics International ,2020年46(8):12686-12694 ISSN：0272-8842
通讯作者：
Wang, Yongqiang
作者机构：
[Guo, Jian; Wang, Yongqiang] Univ South China, Sch Mech Engn, Hengyang 421001, Hunan, Peoples R China.;[Chen, Jingjing] Nanjing Univ Aeronaut & Astronaut, Nanjing 210016, Jiangsu, Peoples R China.
通讯机构：
[Wang, Yongqiang] U;Univ South China, Sch Mech Engn, Hengyang 421001, Hunan, Peoples R China.
关键词：
Deformation;GaN;MD simulation;Mechanical properties;Nanoindentation;Temperature
摘要：
A series of three-dimensional molecular dynamics (MD) simulations was performed to investigate the effect of temperature on the nanoscale deformation behaviour and mechanical properties of c-plane monocrystalline gallium nitride (GaN) under nanoindentation. Simulation results showed that the atomic displacement and strain increased with increasing temperature. Thus, the nucleation and propagation of dislocations in the main slip systems were promoted to intensify the plastic deformation of GaN crystal. Increasing the temperature also contributed to the increase in local phase transition from the wurtzite crystal structure (B4-GaN) to the zinc-blende crystal structure (B3-GaN) and a very evident amorphization of GaN in the indentation zone. Based on the analysis of the load-depth curves, it was found that both the hardness and Young's modulus decreased as the temperature increased. This work can enrich the atomic-level understanding of the effect of temperature on the mechanical response of monocrystalline GaN when subjected to the external loads. © 2020 Elsevier Ltd and Techna Group S.r.l.
语种：
英文
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Removal characteristics and performance of brick-shape permanent magnet–assisted magnetorheological lapping
作者：
Wang, Yongqiang* ;Xu, Zhiqiang;Yin, Shaohui
期刊：
International Journal of Advanced Manufacturing Technology ,2019年105(10):4461-4480 ISSN：0268-3768
通讯作者：
Wang, Yongqiang
作者机构：
[Wang, Yongqiang] Univ South China, Sch Mech Engn, Hengyang 421001, Hunan, Peoples R China.;[Wang, Yongqiang] Univ Queensland, Sch Mech & Min Engn, Brisbane, Qld 4072, Australia.;[Xu, Zhiqiang] Xiangtan Univ, Sch Mech Engn, Xiangtan 411105, Hunan, Peoples R China.;[Yin, Shaohui] Hunan Univ, Natl Engn Res Ctr High Efficiency Grinding, Changsha 410082, Hunan, Peoples R China.
通讯机构：
[Wang, Yongqiang] U;Univ South China, Sch Mech Engn, Hengyang 421001, Hunan, Peoples R China.;Univ Queensland, Sch Mech & Min Engn, Brisbane, Qld 4072, Australia.
关键词：
Magnetorheological lapping;Roughness;Planarity;Removal
摘要：
A brick-shape magnet–assisted magnetorheological (MR) lapping was proposed for ultra-smooth flat surface finish, where a straight ribbon was produced to enhance polishing efficiency. Finite element analysis was performed to understand the magnetic property of the brick-shape magnet. Polishing marks and surface topographies were compared with the removal functions and distributions to reveal effects of translational oscillation, period ratio, work gap, eccentricity and trough speed on surface finish. Trajectories were calculated for kinematical analysis. Polishing performances on K9, sapphire and GaN showed that the polishing area was expanded to 1100 mm2 by the brick-shape magnet. Surface planarity as 1 μm in PV with sub-nanometric roughness were obtained on sapphire, GaN and K9 substrates from removal rates of 0.019, 0.037 and 0.437 μm/min respectively. © 2019, Springer-Verlag London Ltd., part of Springer Nature.
语种：
英文
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Nanotribological Properties of Ga- and N-Faced Bulk Gallium Nitride Surfaces Determined by Nanoscratch Experiments
作者：
Guo, Jian;Qiu, Changjun;Zhu, Huiling;Wang, Yongqiang*
期刊：
Materials ,2019年12(17) ISSN：1996-1944
通讯作者：
Wang, Yongqiang
作者机构：
[Guo, Jian; Wang, Yongqiang; Qiu, Changjun; Zhu, Huiling] Univ South China, Sch Mech Engn, Hengyang 421001, Peoples R China.
通讯机构：
[Wang, Yongqiang] U;Univ South China, Sch Mech Engn, Hengyang 421001, Peoples R China.
关键词：
frictional coefficient;gallium nitride (GaN);nanoscratch;nanotribological properties;wear resistance
摘要：
Through nanoscratch experiments with a spherical diamond indenter, a contrastive study of the nanotribological properties of Ga- and N-faced gallium nitride (GaN) samples was carried out. Nanoindentation results revealed that the elastic modulus of the Ga-faced GaN sample was slightly higher than that of N-faced GaN sample. Particularly, Ga- and N-faced GaN samples exhibited rather different nanotribological properties, and the Ga-faced sample showed a stronger wear resistance. The study indicated that the critical normal load required to cause material removal of N-faced GaN sample was almost two times that of Ga-faced GaN sample. Both Ga- and N-faces exhibited a rather low frictional coefficient at the elastic and elastoplastic stages of material, e.g., similar to 0.06 for Ga-face and similar to 0.075 for N-face when scratching under the progressive normal load. Combined with transmission electron microscopy and X-ray photoelectron spectroscopy, we speculated that, except for the intrinsic atomic arrangements attributed to the non-reverse crystallographic symmetry of c-plane wurtzite GaN, the difference of nanotribological properties between Ga- and N-faces may also be related to the preferential formation of a native oxide layer and a slight lattice damage layer on the N-faced GaN surface. This study can enrich the understanding of the nanotribological properties of Ga- and N-polar-faced bulk monocrystalline GaN materials fabricated by the conventional technique.
语种：
英文
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Ultra-precision finishing of optical mold by magnetorheological polishing using a cylindrical permanent magnet
作者：
Wang, Yongqiang* ;Yin, Shaohui;Hu, Tian
期刊：
International Journal of Advanced Manufacturing Technology ,2018年97(9-12):3583-3594 ISSN：0268-3768
通讯作者：
Wang, Yongqiang
作者机构：
[Wang, Yongqiang] Univ South China, Sch Mech Engn, Hengyang 421001, Hunan, Peoples R China.;[Yin, Shaohui] Hunan Univ, Natl Engn Res Ctr High Efficiency Grinding, Changsha 410082, Hunan, Peoples R China.;[Hu, Tian] Changsha Nanometer Ultra Precis Mfg Technol Ltd C, Changsha 430100, Hunan, Peoples R China.
通讯机构：
[Wang, Yongqiang] U;Univ South China, Sch Mech Engn, Hengyang 421001, Hunan, Peoples R China.
关键词：
Magnetorhelogical polishing;Optical mold;Spatial frequency error;Removal;Roughness;Form accuracy
摘要：
A magnetorheological polishing was proposed to be used for optical glass mold finishing, aiming at suppressing middle spatial frequency errors from ultra-precision grinding while improving surface roughness. A small polishing head, with a cylindrical permanent magnet enveloped by a nonmagnetic outer shell, was also developed. Polishing experiments were performed on concave aspheric tungsten carbide molds. The results demonstrated the developed magnetorheological polishing successfully suppressed the middle spatial frequency errors on the optical mold by decreasing amplitude to 1 nm, while improving overall surface finish to 1 nm in R<inf>a</inf>.<br/> ©2018, Springer-Verlag London Ltd., part of Springer Nature.
语种：
英文
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车辆工程专业实践教学模式探索
作者：
王永强;陈文波;李林升;盛湘飞;罗彪
期刊：
求知导刊 ,2017年(14):143-143 ISSN：2095-624X
作者机构：
南华大学机械工程学院
关键词：
车辆工程专业;实践教学;教学质量
摘要：
实践教学是车辆工程专业实现培养目标的重要环节.文章从实验教学、实习教学和设计教学三个方面,结合南华大学车辆工程专业的培养目标和专业定位,进行实践教学模式探索,以期能提高学生专业技能,推进素质教育,深化教学改革.
语种：
中文
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《汽车理论》课程双语化教学探索
作者：
王永强;李林升;黄坤荣;李必文
期刊：
才智(才情斋) ,2017年(14):114 ISSN：1673-0208
作者机构：
南华大学机械工程学院
关键词：
汽车理论;双语教学;教学效果
摘要：
《汽车理论》是车辆工程专业的一门重要的专业课程,本文通过车辆工程专业在《汽车理论》双语教学方面的探索,让学生使用英语和汉语进行学习、思维和交流,通过课程的学习,达到既掌握学科知识,又熟悉车辆专业词汇的目的。
语种：
中文
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车辆工程专业实验室建设
作者：
王永强;唐德文;李林升;冯栋彦;盛湘飞
期刊：
求知导刊 ,2017年(12):139-139 ISSN：2095-624X
作者机构：
南华大学机械工程学院
关键词：
车辆工程专业;实践教学;实验室建设
摘要：
车辆工程专业是一个实践性较强的专业，实践教学是车辆工程专业实现培养目标的重要环节。根据南华大学机械工程学院（以下简称“我校”）车辆工程实验室现状和专业发展需求，提出车辆工程实验室建设目标，对建设的主要内容进行了规划，满足车辆工程专业的课程实验开设需求，同时，满足学校向“双一流”大学迈进的人才培养需求，兼顾学科发展规划的需要。
语种：
中文
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“汽车构造”精品课程建设
作者：
王永强;陈文波;李林升;盛湘飞;罗彪
期刊：
求知导刊 ,2017年(11):142-142 ISSN：2095-624X
作者机构：
南华大学机械工程学院,湖南 衡阳,421001
关键词：
"汽车构造";精品课程;教学质量
摘要：
:“汽车构造”是车辆工程专业中一门实践性很强的基础课程。文章结合南华大学车辆工程专业定位及特色，从课程体系、建设要求及成果形式等方面对汽车构造精品课程建设进行规划，以提高“汽车构造”课程教学水平和教学质量。
语种：
中文
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A comparative study on magnetorheological planarization using modified magnetic yokes and brick magnet
作者：
Wang, Yongqiang* ;Yin, Shaohui;Huang, Han
期刊：
International Journal of Advanced Manufacturing Technology ,2017年91(5-8):2831-2841 ISSN：0268-3768
通讯作者：
Wang, Yongqiang
作者机构：
[Wang, Yongqiang] Univ South China, Sch Mech Engn, Hengyang 421001, Hunan, Peoples R China.;[Wang, Yongqiang; Yin, Shaohui] Hunan Univ, Natl Engn Res Ctr High Efficiency Grinding, Changsha 410082, Hunan, Peoples R China.;[Huang, Han] Univ Queensland, Sch Mech & Min Engn, Brisbane, Qld 4072, Australia.
通讯机构：
[Wang, Yongqiang] U;[Wang, Yongqiang] H;Univ South China, Sch Mech Engn, Hengyang 421001, Hunan, Peoples R China.;Hunan Univ, Natl Engn Res Ctr High Efficiency Grinding, Changsha 410082, Hunan, Peoples R China.
关键词：
Magnetorhelogical planarization;Magnet brick;Yoke;Stress;Removal;Planarity
摘要：
The geometric shape of magnets was modified to improve surface planarity and polishing efficiency in magnetorheological planarization. Two modified permanent magnetic yokes and a magnetic brick were used as excitation units of magnetic field. Stress analysis indicated that the polishing stress of the horizontal magnetic yoke was smaller than that of the brick magnet, but greater than that of the sloping yoke. The performances of MR planarizations, including removal rate, roughness, and planarity, of the three magnetic sources were also compared. The results showed that the sloping yoke produced the lowest surface finish of 0.6 nm in R
a
and the best planarity of 0.7 μm in PV, and the brick magnet provided the highest removal efficiency.
语种：
英文
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课程导入法在《发动机原理》教学中的应用
作者：
王永强;李林升;盛湘飞;罗彪
期刊：
悦读文摘 ,2017年(3):97 ISSN：1673-0208
作者机构：
南华大学机械工程学院
关键词：
发动机原理;课程导入法;教学效果
摘要：
《发动机原理》课程由于具有较强的理论性和实践性,采用传统教学方式效果不佳,本文提出在《发动机原理》课程教学中应用课程导入法,分析了课程导入法的作用,对《发动机原理》课程的导入法教学进行设计,并在教学实践中获得良好效果。
语种：
中文
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《汽车构造》网络课件开发探析
作者：
王永强;李林升;李必文;黄坤荣
期刊：
悦读文摘 ,2017年(15):12 ISSN：1673-0208
作者机构：
南华大学机械工程学院
关键词：
汽车构造;网络课件;教学模式
摘要：
《汽车构造》课程是车辆工程专业的一门承前启后的专业基础课,需避免单纯的书本和课堂教学,本文通过《汽车构造》网络教学课件开发,利用声音、影像、动画、图形、图像及三维造型等元素帮助学生完成理论到实际衔接阶段的学习,在教学实践中获得良好效果。
语种：
中文
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小口径非球面光学模具斜轴磨削加工试验研究
作者：
王永强;尹韶辉;李林升;盛湘飞;邱长军
期刊：
南华大学学报(自然科学版) ,2016年30(4):49-55 ISSN：1673-0062
作者机构：
南华大学 机械工程学院，湖南 衡阳421001;湖南大学 国家高效磨削工程技术研究中心，湖南 长沙410082;湖南大学 国家高效磨削工程技术研究中心,湖南 长沙,410082;南华大学 机械工程学院,湖南 衡阳,421001;[王永强; 李林升; 邱长军; 盛湘飞] 南华大学
关键词：
小口径非球面光学模具;斜轴磨削;表面粗糙度;面形精度
摘要：
小口径非球面光学模具采用超精密斜轴磨削加工避免传统直交磨削法中砂轮轴与工件发生干涉的问题。选用碳化钨和不锈钢材料作为工件,采用斜轴磨削法,对小口径非球面光学模具磨削加工进行试验研究。结果表明：碳化钨模具获得的表面粗糙度和面形精度分别为Ra 1 nm和PV 182 nm,不锈钢模具获得的表面粗糙度和面形精度分别为Ra 4 nm和PV 304 nm,说明碳化钨模具的磨削效果明显优于不锈钢模具,且磨削后表面质量随工件转速、砂轮转速及砂轮粒度增加而变好,随磨削深度及进给深度增加而变差。
语种：
中文
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应用环形磁场控制的微粉砂轮制备及其磨削性能
作者：
龚胜;王永强;尹韶辉;陈逢军;康仁科;...
期刊：
机械工程学报 ,2016年52(17):78-85 ISSN：0577-6686
通讯作者：
Yin, Shaohui(yinshaohui@hnu.edu.cn)
作者机构：
[龚胜; 王永强; 陈逢军; 叶冰; 尹韶辉] National Engineering Research Center for High Efficiency Grinding, Hunan University, Changsha, 410082, China;[胡天] Changsha Nano-meter Ultra-precision Manufacturing Technology Ltd. Corp., Changsha, 430100, China;[康仁科] Key Laboratory for Precision and Non-traditional Machining Technology of Ministry of Education, Dalian University of Technology, Dalian, 116023, China;[王永强] School of Mechanical Engineering, University of South China, Hengyang, 421001, China
通讯机构：
National Engineering Research Center for High Efficiency Grinding, Hunan University, Changsha, China
关键词：
超精密磨削;环形磁场控制;磨粒规则排布;微粉砂轮
摘要：
在超精密磨削中,金刚石微粉砂轮的磨粒分布均匀性对提高磨削表面质量至关重要,为了使微粉磨粒规则排布,提出了一种采用环形磁场控制磨粒规则排布的砂轮制备方法,制备了多种金刚石微粉砂轮,使用磁场控制制备的微粉砂轮对硬质合金YG8进行了平面及非球面磨削试验。结果表明:应用环形磁场控制可使金刚石微粉砂轮的磨粒实现规则排布,极大改善砂轮加工性能,利用环形磁控方法制备的砂轮可获得最佳表面粗糙度Ra3 nm、最佳面形精度PV318 nm的光滑镜面。
语种：
中文
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