砷化镓声电荷转移延迟线的设计与工艺研究

由于声电荷转移(ACT)这一新颖的高速缓冲抽样技术的发明,使得新一代高速高频信号处理器件的实现成为可能。本文研究了第二代平面结构的ACT器件转移沟道的电位分布特性,给出了平面结构ACT延迟线的设计,并研究了ACT器件的工艺实现。     

Growth rate and surface microstructure in α(6H)–SiC thin films grown by chemical vapor deposition

Monocrystalline 6H-SiC thin films have been epitaxially grown on off-axis 6H-SiC {0001} substrates in the temperature range of 1623–1873 K via chemical vapor deposition. The growth rate was a strong function of the growth temperature and the reactant gas concentration. The activation energies for growth were 64 kJ/mole and 55 kJ/mole for the (0001) Si face and the (0001) C face, respectively. The concentration of growth pits in the films increased as a function of decreasing deposition temperature, increasing concentration of reactant gases and increasing off-axis orientation. Beta-SiC islands were also observed in the epilayers when the (SiH₄ + C₂H₄)/H₂ ratio was ≥2.5:3000.     

Off-Optimum Cure of Aerospace Epoxy Adhesives

Four epoxy film adhesives used in aircraft manufacture and repair have been examined to establish the effect of deviation from the cure cycle specified by the manufacturer. In addition to the variation of the cure cycle, two surface preparations of the aluminium adherends (chromic acid etch or grit blast followed by silane treatment) were evaluated. Thermal analysis was used to examine the cure envelope of the adhesive, and its extent of cure and glass transition temperature. The adhesive properties were assessed by shear strength (in both single lap joints and in Iosipescu configuration), durability (Boeing wedge test) and chemical resistance to selected aggressive fluids. The sensitivity of the performance of a particular adhesive to offoptimum cure conditions depends on its composition and needs to be determined, not predicted.     

能量"三环节"理论在原油蒸馏装置扩能改造中的应用

中国石化扬子石化股份有限公司炼油厂在第一套常减压蒸馏装置扩能改造中，使用了多项节能技术以实现能量的优化利用。本文以标定数据为基础，运用能量“三环节”理论对该装置的用能状况进行了计算和分析，从能量利用角度对装置的扩能改造效果进行了评价，并为装置的进一步优化能量利用提出了相应措施。     

A new approach to the mechanism of chlorine evolution: Separate examination of the kinetic steps using ac impedance on a rotating thin ring electrode

In the absence of a bulk diffusion effect, it is shown for the first time that the impedance spectra for the chlorine evolution reaction on a rotating thin ring electrode comprise three consecutive semicircles in the capacitive half of the complex plane. The first (highest frequency) semicircle is due to the charge-transfer resistance for chloride discharge and the simultaneous chlorine adsorption coupled to the double-layer capacitance. The second semicircle (around 5 Hz) is due to the adsorption and desorption of a chlorine intermediate. The third (lowest frequency, around 0.5 Hz) semicircle is due to the relaxation of surface oxygen species. The impedance data allow the steps of the overall reaction to be examined individually. On a Pt surface the rate of chloride discharge and simultaneous chlorine adsorption (the admittance of the first semicircle) is first order with respect to chloride concentration and has a potential-dependence close to 58 mV/decade. The rate of the adsorption and desorption process (the admittance of the second semicircle) is second order with respect to chloride concentration, and has a potential dependence close to 30 mV/decade. The time constant for the adsorption/desorption processes is ca 20 ms, independent of electrode potential in the range studied. These features are consistent with a mechanism in which a faster discharge reaction (Cl⁻ Cl_ad + e) is followed by a slower surface combination reaction (2Cl_ad → Cl₂), but inconsistent with mechanisms in which ion + atom desorption is predominant, the initial chloride discharge is slow, or a unipositively charged chlorine species is involved.     

航空齿轮表面硬化层断裂性能研究

按照航空齿轮的具体工艺过程，对材料12Cr2Ni4A的拉伸试样和断裂试样进行设计和加工，通过三点弯曲实验，重点研究了齿轮材料硬化层的硬度分布，硬化试样拉伸力学性能参数和断裂性能参数，实验结果表明，所采用试样的加工工艺方案是可行的，所获得的Kc基本反映我国航空硬化齿轮材料的断裂性能特征，为定量预测航空硬化齿轮疲劳寿命提供实验和理论分析的依据。     

撞击流管式反应制备超细氧化锆粉体

我国氧化锆粉体产业目前基本上“精进粗出”，迫切需要开发氧化锆粉体备新工艺，特别是具有高附加值的纳米氧化锆粉体制备技术，液相反应沉淀法具有成本低，易于工业化等优点而成为研究的热点。本文采用撞击流管式反应新工艺，撞击流接触反应强化了过程的微观混合。实现了均匀成核，使得成核过程易于控制，而管式反应器的独特设计克服了返混，因而使得反应沉淀过程易于控制，粒子分布窄。用该工艺结合醇热处理表面改性制备的超细氧化锆粉体。平均粒径约为14nm，粒度分布窄并无硬团聚发生。该方法过程简单，易于工业化大生产。     

优化SMC模压工艺控制制品收缩率和表面粗糙度

优化SMC模压工艺参数：模压压力分为二阶段，选定最佳压力释放时机和压力；适宜降低模压温度。可显著降低SMC制品的固化收缩率，提高其表观质量、试验表明，同时采用的线收缩率和表面粗糙度两种检测和村定方法具有很好的同一性。     

掺杂聚苯胺的表面接枝共聚改性

化学氧化法制备的聚苯胺表面的亲水性差，本文在本征态和不同酸掺杂志聚苯胺的表面上接枝共聚丙烯丙烯酸和丙烯酰胺，明显地改善了聚苯胺的表面亲水性。结果显示，聚苯胺表面经过等离子体处理后，有利于丙烯酸和丙烯酰胺在聚苯胺表面上的接枝共聚，随着接枝量增多，导电率则随之有所下降，此外，利用ＳＥＭ和反射ＩＲ表征了改性反聚苯胺表面的形态和结构。