Electron beam evaporated carbon nanotube dispersed SnO2 thin film gas sensor

Carbon nanotube (CNT) is a useful material for gas-sensing applications because of its high surface to volume ratio structure. In this work, multi-wall CNTs are incorporated into tin oxide thin film by means of powder mixing and electron beam evaporation and the enhancement of gas-sensing properties is presented. The CNTs were combined with SnO₂powder with varying concentration in the range of 0.25–5% by weight and electron beam evaporated onto glass substrates. From AFM and TEM characterization, CNT inclusion in SnO₂thin film results in the production of circular cone protrusions of CNT clusters or single tube coated with SnO₂layer. Experimental results indicate that the sensitivity to ethanol of SnO₂thin film increases by the factors of 3 to 7, and the response time and recovery time were reduced by the factors of 2 or more with CNT inclusion. However, if the CNT concentration is too high, the sensitivity is decreased. Moreover, the CNT doped film can operate with good sensitivity and stability at a relatively low temperature of 250–300^∘C. The improved gas-sensing properties should be attributed to the increasing of surface adsorption area of metal oxide produced by CNT protrusion.     

等截面单跨超静定梁杆端弯矩的统一算式

本文介绍的统一算式是各种支座形式受集中荷载作用,等截面单跨超静定梁杆端弯矩归为统一的计算公式。对受均布荷载作用的情况,杆端弯矩可以通过积分求出。     

Epitaxial growth and thermal-conductivity limit of single-crystalline Bi2Se3/In2Se3 superlattices on mica

Nano Research - Thermal transport in superlattices is governed by various phonon-scattering processes. For extracting the phonon-scattering contribution of hetero-interfaces in chalcogenide...     

Geometry dependence of microstructure and microhardness for selective electron beam-melted Ti–6Al–4V parts

In an additive-manufactured metallic part, distinct and different microstructure and mechanical properties may exist in different areas due to differences in shape and location. Two parts, one with straight-finned structure and the other with curve-finned structure, were fabricated by the selective electron beam melting method using pre-alloyed Ti–6Al–4V ELI powder. Microstructural characterisation of these two parts that have varying fin thickness and shape was carried out to investigate the synthetical influence of 2D planar build geometry and in-fill hatching strategy on selective electron beam melting. It was found that the β interspacing is larger in the curve-finned structure, leading to a lower microhardness as compared to the straight-finned structure. It suggests a slower cooling rate in the curve-finned structure due to the differences in build geometry and in-fill hatching strategy.     

Theoretical research on naturally curved and twisted beams under complicated loads

This paper presents an analytical method for the study of naturally curved and twisted beams under complicated loads, with special attention devoted to the solving process of governing equations which take into account the effects of torsion-related warping as well as transverse shear deformations. The solutions derived in this paper can be used for the analysis of the beams, including the calculation of various internal forces, stresses, strains and displacements. These governing equations, in special cases, can be readily solved and yield the solutions to the problem. A generalized warping coordinate for a curved coplanar beam subjected to the action of vertical distributed loads is given for verification.     

用δ函数解振动问题

本文通过引入δ函数,给出几种用以简化工程振动计算的方法,借以推广δ函数在振动工程中的应用。     

重核离子束成分的加速器质谱分析

为拓展加速器质量技术测量范围及测量放射性核束成分,建立了利用入射离子发射特征Ｘ射线鉴别同量异位素的方法,开展了利用ＡＭＳ测量重核离子束成分的工作。     

用于ICF的大尺寸位相元件的设计

发展了用于实现ＩＣＦ靶面均匀照明的大口径连续型位相元件设计的新方法,并且在工艺上进行了初步试制。等厚干涉图显示达到了预期的大口径、连续的要求     

Pt and W ohmic contacts to p-6H-SiC by focused ion beam direct-write deposition

Low resistance Pt and W ohmic metallizations to p-type 6H-SiC, using focused ion beam (FIB) surface-modification and in-situ direct-write metal deposition without annealing, are reported. FIB (Ga) surface-modification and in-situ deposition of Pt, and W showed minimum contact resistance values of 2.8 × 10⁻⁴ ohm-cm² to 2.5 × 10⁻⁴ ohm-cm², respectively. A comparison with ex-situ pulse laser deposited Pt on surface-modified areas showed comparable contact resistance values and similar behavior. Auger and secondary ion mass spectroscopy analysis showed a significant (∼4% a.c.) incorporation of Ga within a 15 nm distance from the SiC surface with surface-modification. Atomic force micros-copy studies showed that surface-modification process smooths out the SiC surface significantly.     

亚微米电子束曝光机激光工件台位置显示系统

介绍了工件台位置显示系统的组成,工作原理及软件设计。由于采用单片机控制技术,从而保证了系统的显示精度和运行可靠性。