润滑油添加剂对PTFE复合材料摩擦磨损性能的影响

利用MM-200型摩擦磨损试验机考察了液体石蜡中的二烷基二硫代磷酸锌(ZDDP)对聚四氟乙烯(PTFE)复合材料摩擦磨损性能的影响，然后用EMA-8100电子探针对摩擦表面进行了分析，进而探讨了润滑油添加剂对PTFE复合材料摩擦磨损性能的影响机理。     

烧结方法对MoS2填充激光凹坑织构表面摩擦磨损性能的影响

在45钢试件表面激光加工出凹坑织构,并且采用常压、保压烧结方法制备出MoS2填充凹坑织构试件.通过销盘式摩擦磨损实验对比了两种试件表面的摩擦磨损性能,观察了填充表面、磨损表面、对摩球表面,测量了 MoS2的脱落面积、磨痕截面面积及对摩球磨损体积.实验结果表明,与常压烧结方法相比,保压烧结方法使试件表面的未填充率降低了 ...     

CO_2激光辐照对PZT-4陶瓷压电性能的影响

常温常压下,采用CO2激光辐照带有电极的PZT-4陶瓷片,当激光辐照时间分别为2、5和10 s时,在适当的激光功率密度下可使其压电应变常数d33从380 pC/N下降为零。系统地研究了激光功率密度和激光辐照时间对PZT-4陶瓷压电性能影响的规律。XRD、拉曼光谱和退火实验结果表明:CO2激光辐照使d33下降为零的原因是由于激光热效应导致PZT-4陶瓷的电畴排列失序,极化状态消失;而激光辐照未使其物相发生变化。     

SiO2含量及粒径对SiO2/聚烯烃复合材料性能的影响

采用溶液法制备了SiO_2填充聚烯烃复合材料,系统研究了SiO_2含量及粒径对SiO_2/聚烯烃复合材料显微结构、力学性能、吸水率、介电性能的影响。结果表明,随着SiO_2含量的增加,复合材料的拉伸强度先增大到一个最大值然后减小,断裂伸长率先稍有增大后逐渐减小,介电常数、介电损耗和吸水率则随SiO_2含量的增加而增加;相同SiO_2填充量时,复合材料拉伸强度、断裂伸长率、介电常数、介电损耗和吸水率均随SiO_2粒径的增大而减小,当SiO_2的粒径为10μm时,复合材料具有最低的介电常数、介电损耗和吸水率。     

Effect of irradiation on the properties of nanocrystalline silicon carbide films

The effect of irradiation with electrons on the optical and electrical properties of the nanocrystalline rhombohedral 21R-SiC and 27R-SiC films is studied. The cycles of irradiation of nanocrystalline SiC films on sapphire substrates with electrons with the energy 10 MeV are conducted in the range of fluences from 5 × 10¹⁴ to 9 × 10¹⁹ cm^?2. It is established that, at the irradiation doses above 10¹⁹ cm^?2, the optical absorption of the films at the photon energies E > E _g becomes less efficient than the optical absorption of unirradiated films. It is established that the Urbach energy as a function of the irradiation dose exhibits a minimum at the dose ～10¹⁷ cm^?2 for the 21R-SiC films and ～5 × 10¹⁷ cm^?2 for the 27R-SiC films, suggesting that radiation induces some ordering in the films. As the dose is increased from 5 × 10¹⁷ up to 9 × 10¹⁹ cm^?2, an increase in the Urbach energy and a decrease in the optical band gap are observed. The effect is attributed to an increase in the concentration of radiation defects in the films.     

外压调制对Cr-Se共掺杂单层MoS2光电特性的影响

采用基于第一性原理的贋势平面波方法,对比研究了Cr-Se共掺杂单层MoS2未施应变和(0001)面施加应变的光电特性。计算结果表明:未施加应变体系属直接带隙半导体,张应变下体系的带隙值随应变增加而减小,压应变下带隙值随应变增加先增加后减小,在应变为-6%时转化为Γ-M间接带隙半导体,带隙值达到极大值1.595eV;介电函数和折射率随张应变的增加而增加,随压应变增加先减小后增大,在压应变为-6%时达到极小值3.627和1.905;光电导率和能量损失函数随张应变增加而减小,随压应变增加先增加后减小,应变分别为-5%和-2%时达到极大值2.588和9.428。可见,应变能更精细地调制Cr-Se共掺杂单层MoS2的光电特性。     

氧等离子体对少层MoS2及其场效应晶体管的影响研究

通过氧等离子体对MoS2材料及其场效应晶体管进行处理,用AFM、拉曼光谱、XPS和I-V测试对材料和器件性能进行表征,系统研究了氧等离子体对MoS2材料及其器件性能的影响。实验结果表明,氧等离子体处理可以有效去除MoS2材料和器件制备过程中引入的有机杂质,将MoS2的表面粗糙度降低到了0.27 nm。同时氧等离子体将表层MoS2氧化成MoO3,降低了器件接触区域MoS2与金属之间的费米能级钉扎效应,使器件开关比高达3.3×10^6。对MoS2器件沟道进行处理时,氧离子穿过MoO3插入到MoS2晶格中从而对沟道形成p型掺杂。     

Effect of temperature and moisture on the luminescence properties of silicone filled with YAG phosphor

In order to determine the environmental effects on the luminescence properties of a phosphor layer for high-power light emitting diodes,a high humidity and temperature test(85℃/85%RH) and a thermal aging test (85℃) were performed on silicone/YAG phosphor composites.The luminescence properties of silicone/phosphor composites are monitored by a fluorescence spectrometer.The results show that high temperature could result in an increase in conversion efficiency of composites during the early aging stage and red shift of YAG phosphor;and high humidity could result in a significant decrease in conversion efficiency of composites while having a small influence upon the optimal excitation wavelength of the YAG phosphor.     

Effect of temperature and moisture on the luminescence properties of silicone filled with YAG phosphor

In order to determine the environmental effects on the luminescence properties of a phosphor layer for high-power light emitting diodes, a high humidity and temperature test (85 ℃/85%RH) and a thermal aging test (85 ℃) were performed on silicone/YAG phosphor composites. The luminescence properties of silicone/phosphor composites are monitored by a fluorescence spectrometer. The results show that high temperature could result in an increase in conversion efficiency of composites during the early aging stage and red shift of YAG phosphor; and high humidity could result in a significant decrease in conversion efficiency of composites while having a small influence upon the optimal excitation wavelength of the YAG phosphor.     

MXene Electrode for the Integration of WSe2 and MoS2 Field Effect Transistors

Recently, MXenes, which are 2D early transition metal carbides and carbonitrides, have attracted wide attention because of their excellent conductivities. Here, the electrode applications of Ti₂C(OH)_xF_y, one member of the MXene family, in WSe₂ and MoS₂ field effect transistors (FETs) are assessed. Kelvin probe force microscopy analysis is performed to determine its work function, which is estimated to be ≈4.98 eV. Devices based on WSe₂/Ti₂C(OH)_xF_y and MoS₂/Ti₂C(OH)_xF_y heterostructures are fabricated with the mechanical transfer method and their electronic performances evaluated. The temperature‐dependent current–voltage transfer characteristics of the devices are determined to extract their Schottky barrier heights. The hole barrier between WSe₂ and Ti₂C(OH)_xF_y is estimated to be ≈0.23 eV and the electron barrier between the MoS₂ band and Ti₂C(OH)_xF_y is ≈0.19 eV, which indicates that the pinning effect occurs at the MoS₂/Ti₂C(OH)_xF_y interface but not at the WSe₂/Ti₂C(OH)_xF_y interface; this difference arises because of the difference between the band structures of WSe₂ and MoS₂. A complementary metal–oxide–semiconductor inverter based on these electrode properties of Ti₂C(OH)_xF_y with MoS₂ (n‐channel) and WSe₂ (p‐channel) is fabricated, which demonstrates that Ti₂C(OH)_xF_y is a promising electrode for future nanoelectronics applications.     

硅灰石填充UHMWPE基复合材料的干滑动磨损

超高分子量聚乙烯 (ＵＨＭＷＰＥ)是一种新型工程塑料 ,分子量一般在 1 5 0万以上 ,与普通聚乙烯具有相同的分子结构。它具有耐磨损、耐腐蚀、耐冲击、自润滑、摩擦系数小、耐低温等优良特性。却存在表面硬度低、强度低、耐热性能差、有蠕变性等缺点[1～ 3] 。本文研究的重点是硅灰石填充ＵＨＭＷＰＥ的干滑动磨损性能及机理。实验部分试验所用ＵＨＭＷＰＥ的分子量为 2 5 0万。采用乙烯基三乙氧基硅烷和ＮＴ -1 0 5酞酸酯偶联剂进行表面处理。经过偶联剂表面处理的硅灰石与ＵＨＭＷＰＥ按一定的比例装入Ｖ形混料机进行充分混合 ,然后装入模…