Influence of zero-loss filtering on electron optical phase contrast

Complex scattering amplitudes are used to calculate the phase contrast of colloidal gold particles. Comparison of measurements of the phase contrast intensity at the centre of the gold particle as a function of defocus for unfiltered and zero-loss filtered images demonstrates the increase in phase contrast achieved by zero-loss filtering even for a thick carbon substrate film. The granulation of amorphous germanium films is measured by the spatial rms (root mean square) values of image intensity in a defocus series.     

AlN 粉末制备的热力学分析和实验研究

对制备 AlN 的体系 AlCl_3-NH_3-N_2进行了热力学分析,确立了 AlN 粉末合成所需要的热力学条件.在700～1000℃下,利用无水 AlCl_3和 NH_3的化学气相淀积反应合成得到了高纯 AlN 超细粒子粉末,研究了反应温度、AlCl_3浓度和总流量等对 AlN 粉末理化性质的影响.实验确立了产物低温和高温热处理条件.     

SiC粒子增强铸造Al基复合材料的研制

本文用真空烘烤封罐法对 SiC 粒子进行预处理,在固液两相区内搅拌添加,制造了铸造 Al 基复合材料。测试表明,该复合材料具有铸造性能好,力学性能高的优点,适用于采用压铸、石膏型精密铸造、金属型铸造等工艺方法成型的活塞、连杆等要求苛刻的零件。     

颗粒增强TiAl基复合材料及其Si的韧化作用研究EI

运用ＸＤ工艺制备了颗粒增强ＴｉＡｌ基复合材料。增强颗粒均匀分布于ＴｉＡｌ基体中并细化ＴｉＡｌ合金。通过在ＴｉＢ_２／ＴｉＡｌ、ＴｉＣ／ＴｉＡｌ复合材料中加入适量的Ｓｉ，颗粒增强ＴｉＡｌ基复合材料的室温延性得到了改善。     

Handling of fine-particles by time-averaged particle driving method in plasmas

We developed a noble technique for the fine-particle handling in plasmas. In this method a pair of point electrodes are introduced in the plasma, to which positive pulses are applied alternatively. When the pulse repetition period is shorter than the particle response time, the particles feel only time-averaged force because of their large mass. Spatial profile of the equivalent potential of the time-averaged force varies from a circle to an ellipse with an increase in the local discharge at the electrodes. The particles are eventually transported toward a middle point between two point-electrodes, being almost independent of their initial positions. This method is quite effective for converging fine particles in the plasma.     

烧结直接淬火对WC－TiC－Co合金WC相微观结构及力学性能的影响

本文以ＴＥＭ和ＸＲＤ为主要手段，研究ＷＣ－ＴｉＣ－Ｃｏ硬质合金（ＹＴ１４）在直接淬火后ＷＣ相的微观结构和微观应力，比较了常规烧结态与淬火态试样ＷＣ相之间的差异，探讨了直接淬火对合金力学性能的影响。结果表明，在保持合金其他性能不降低的同时，直接淬火的抗弯强度比常规烧结提高２８％左右。并首次发现，经直接淬火热处理的ＹＴＩ４合会中与Ｃｏ相相邻的ＷＣ晶粒边界出现滑移台阶，这是淬火过程中热应力使ＷＣ晶粒内位错在｛０００１｝密排面聚集，并可能沿｛０００１｝＜１１２０＞易滑移系统强滑移的结果。直接淬火试样的微观应力比重新加热淬火的低。     

Formation of WC/Ni hard alloy coating by laser cladding of W/C/Ni pure element powder blend

WC/Ni coating was formed by laser cladding of a W/C/Ni powder blend. The formed WC crystals have rectangular or quadrangle cross-section shapes with size of 2–30 μm. Step, twist and cross growth morphologies of WC formation were observed. The coating contains WC, CW_3, WNi, FeW₃C, Fe₆W₆C, W₃O, W, C, and (Fe,Ni) phases.     

纳米碳颗粒/氮化碳复合材料的制备及光催化性能

通过一步热聚合法制备纳米碳颗粒/氮化碳复合材料,利用XRD、FTIR、TEM、DRS、PL等手段对纳米碳颗粒/氮化碳进行了系统表征,并考察其光催化降解罗丹明B的光催化性能。结果表明,纳米碳颗粒的负载可以显著改善复合材料的可见光吸收能力及光生电子/空穴的分离效率,当加入纳米碳颗粒的质量为10 mg时,所得到的纳米碳颗粒/氮化碳2在20 min内对罗丹明B的降解率可以达到96.5%,明显优于纯氮化碳材料。此外,纳米碳颗粒/氮化碳复合材料还表现出良好的稳定性。     

离心铸造法制备Al3Ti/Al原位自生功能梯度复合材料

采用离心铸造法，用TiO2粉末与纯铝熔液原位反应生成Al3Ti颗粒增强相，获得了组织和性能在径向上呈梯度分布的Al3Ti/Al功能梯度复合材料。考察了材料的显微组织和硬度，Al3Ti颗粒和材料硬度在径向上由外向内呈梯度分布。研究分析了离心和转速、TiO2加入量和激冷强度对复合材料组织和硬度的分布梯度的影响。结果表明，这些因素对复合材料组织和性能分布梯度的影响较大。     

Micron-Scale Soft Actuators Fabricated from Multi-Shell Polystyrene Particle-Gold Nanoparticle Nanohybrids

Actuators made of soft matter are needed for a variety of fields ranging from biomedical devices to soft robotics to microelectromechanical systems. While there are a variety of excellent methods of soft actuation known, the field is still an area of intense research activity as new niches and needs emerge with new technology development. Here, a soft actuation system is described, based on a core-multi-shell particle, which moves via photothermal expansion. The system consists of a novel polystyrene-based thermally expandable microsphere, with a secondary shell of a silicate-silane graft copolymer, to which gold nanoparticles are covalently linked. The gold nanoparticles act as photothermal nano-transducers, converting light energy into the thermal energy necessary for microsphere expansion, which in turn results in material movement. Actuation is shown in isolated particles in thermal and photothermal regimes using metal ceramic heaters or 520 nm laser illumination, respectively. Macroscale actuation is demonstrated by making a composite material of particles suspended in the transparent elastomer polydimethylsiloxane. The sample demonstrates an inchworm-like movement by starting from an arched geometry. Overall, this work describes a new particle-based actuation method for soft materials, and demonstrates its utility in driving the movement of a composite elastomer.