期刊：
Review of Scientific Instruments,2020年91(4):043308-1-043308-4 ISSN：0034-6748
通讯作者：
Zhou, H. Y.
作者机构：
[Yu, Y.; Zhou, H. Y.] Univ Sci & Technol China, Sch Phys, Jinzhai Rd 96, Hefei 230026, Peoples R China.;[Xu, P.] Univ South China, Sch Resources Environm & Safety Engn, Changsheng Rd 28, Hengyang 421001, Peoples R China.;[Qiu, C. J.] Univ South China, Sch Mech Engn, Changsheng Rd 28, Hengyang 421001, Peoples R China.
通讯机构：
[Zhou, H. Y.] U;Univ Sci & Technol China, Sch Phys, Jinzhai Rd 96, Hefei 230026, Peoples R China.
摘要：
Large-grain-sized polycrystalline diamond films are fabricated by electron assisted chemical vapor deposition. A pure SP3 carbon bond in the cubic lattice structure is confirmed by Raman spectrum analysis. The grain size is on the order of several hundreds of mu m or larger. Interlaced-finger electrodes are imprinted onto a 6 x 6 mm(2) x 500 mu m film to fabricate the x-ray detector. The width of every finger is 25 mu m, and the distance between nearby fingers is 25 mu m. Strong x ray irradiates when a pulsed current flows through a double-layer nested tungsten wire array in the Z-pinch. This diamond detector now works as one of the main x-ray detectors for the Z-pinch device. The diamond detector is calibrated using a plastic scintillator. The comparison between the signal measured by these two methods confirms that the large-grain-sized polycrystalline diamond is a good candidate for the detection of nanosecond pulsed x ray.
摘要：
A diamond film with a size of 6 x 6 x 0.5 mm(3)is fabricated by electron-assisted chemical vapor deposition. Raman spectrum analysis, x-ray diffraction and scanning electron microscope images confirm the high purity and large grain size, which is larger than 300 mu m. Its resistivity is higher than1012 omega cm.<iInterlaced-finger electrodes are imprinted onto the diamond film to develop an x-ray detector. Ohmic contact is confirmed by checking the linearity of its current-voltage curve. The dark current is lower than 0.1 nA under an electric field of 30 kV cm(-1). The time response is 220 ps. The sensitivity is about 125 mA W(-1)under a biasing voltage of 100 V. A good linear radiation dose rate is also confirmed. This diamond detector is used to measure x-ray on a Z-pinch, which has a double-layer 'nested tungsten wire array'. The pronounced peaks in the measured waveform clearly characterize the x-ray bursts, which proves the performance of this diamond detector.
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.
摘要：
目的提高锆合金在高温高压环境中耐动水腐蚀性能。方法利用多弧离子镀技术（MAIP）在Zr-4合金表面分别制备了Al2O3涂层和Cr/Ti AlN复合涂层,利用磁控溅射技术（MS）在Zr-4合金表面制备了Ti N涂层。通过堆外高压釜实验,对比研究了三种不同涂层的耐高温高压动水腐蚀性能,利用自动划痕仪检测膜基结合力,利用XRD分析涂层的物相成分,利用SEM观察涂层腐蚀前后的微观形貌,利用EDS对涂层元素种类与含量进行分析。结果多弧离子镀技术制备的Al2O3涂层和Cr/Ti Al N涂层致密度较高,但表面存在少量大颗粒与微孔洞;磁控溅射技术制备的Ti N涂层均匀平整,表面大颗粒较少。Al2O3涂层、Ti N涂层和Cr/Ti Al N涂层可承受的临界载荷分别为26、16、26.5 N。在实验条件下,Cr/Ti Al N涂层和Ti N涂层表面均发生了剥落或腐蚀现象,且这两种试样表面均检测出大量的Zr O2,而Al2O3涂层几乎未被破坏,基体得到了充分防护。结论利用多弧离子镀技术在Zr-4合金表面制备的Al2O3涂层和Cr/Ti Al N涂层的膜基结合力较高,利用磁控溅射技术制备的Ti N涂层的膜基结合性能较差,其中Al2O3涂层具备良好的耐腐蚀性能,在高温高压动水腐蚀环境中能够有效地保护锆合金基体。
摘要：
The hybrid architectures comprising different types of nano-structured WO(3 )particles were prepared via facile surfactant-and template-free hydrothermal synthesis process. We demonstrate that morphology of the fabricated hybrid nanomaterials can be manipulated but the phases of those nanomaterials are still monoclinic and hexagonal hybrid structure via tuning the proportion of the reagents. The synthesis mechanism and the gas-sensing properties of the harvested nanomaterials have also been investigated. The as prepared WO3 nano-particles with hybrid architectures exhibit excellent gas-sensing functions to ethanol gas at the optimal temperature as low as 350 degrees C under the low concentration of 35 ppm, rendering them a promising sensing material for the on-site detection of ethanol. (C) 2019 Elsevier B.V. All rights reserved.
作者：
Longzhang Shen*;Changjun Qiu;Xiaoyan Wu;Changxing Han;Liangbin Hu
期刊：
The Journal of Engineering,2019年2019(13):402-405 ISSN：2051-3305
通讯作者：
Longzhang Shen
作者机构：
[Longzhang Shen; Changjun Qiu; Changxing Han; Liangbin Hu] School of Mechanical Engineering, University of South China, Hengyang, Hunan, 421001 People's Republic of China;School of Civil Engineering, University of South China, Hengyang, Hunan, 421001 People's Republic of China;[Xiaoyan Wu] School of Mechanical Engineering, University of South China, Hengyang, Hunan, 421001 People's Republic of China<&wdkj&>School of Civil Engineering, University of South China, Hengyang, Hunan, 421001 People's Republic of China
通讯机构：
[Longzhang Shen] S;School of Mechanical Engineering, University of South China, Hengyang, Hunan, 421001 People's Republic of China
关键词：
mobile computing;retail data processing;vending machines;Internet;physical stores;online stores;removable vending machine;key implementation technology;wireless location technology;route planning;mobile technology
摘要：
As a supplement to physical stores and online stores, vending machines are gradually becoming the third largest consumption mode. This article aims to design a removable vending machine, which can automatically move in front of the users to meet their demands, so as to realise a better shopping experience for people. The network structure for the vending machine was analysed and designed, and research on the wireless location technology and route planning of the vending machine is hoped to provide some reference value for the mobile technology of the vending machine.
作者机构：
[朱红梅; 李柏春; 朱锦云; 邱长军] School of Mechanical Engineering, University of South China, Hengyang;421001, China;[唐忠锋] Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai;201800, China;[朱红梅; 李柏春; 朱锦云; 邱长军] 421001, China
摘要：
The coatings are fabricated using austenitic stainless steel powder with various contents of carbon and boron via laser remanufacturing technique. A new synchronous lateral powder feeding device is adopted to avoid surface oxidation of molten pool. The authors find that the strength can be increased but plasticity is decreased of with the rise of boron content due to the formation of lamellar borides phase structures, which are very brittle and have high hardness. In addition, the authors also find that the tensile strength and hardness are enhanced by increasing the content of carbon, while the plasticity is deteriorated due to the formed carbide in the grain of the austenitic stainless steel coating. The coatings of austenitic stainless steel powder with various contents of carbon and boron are fabricated using laser remanufacturing technique. A new synchronous lateral powder feeding device is adopted to avoid surface oxidation of molten pool. The tensile strength and hardness are enhanced by increasing the content of carbon and boron, while the plasticity is deteriorated.
