叠加能量C^＋注入SiO2薄膜的光致发光特性

首次采用叠加能量离子注入技术制备Ｃ＾＋注入ＳｉＯ２薄膜样品，室温下观测到很强的蓝光发射。通过测量样品的光致发光谱对退火条件的依赖关系，研究了样品的发光特性。对发光机制进行了初步探讨。     

非掺杂InP的低温光致发光研究

研究了2K低温下非有意掺杂InP单晶的光致发光谱,对近带边的辐射跃迁进行了仔细分析,报道了InP单晶在大功率光激发时束缚于中性施主的激子跃迁发光相对减弱、而束缚于中性受主的激子跃迁发光相对增强的现象,并探讨了其机制,确认了材料中存在Mg、Zn等残余受主杂质,并计算得到Mg受主的离化能为41.5meV.     

Cu－Zn－Al合金中贝氏体的有序性

本文用Ｘ射线研究了Ｃｕ－２０Ｚｎ－６Ａｌ（ｗｔ％）合金中贝氏体结构的有序性，并与马氏体结构进行了比较，实验表明，从高温Ｂ２母相和低温Ｌ２１母相生成的贝氏体中（１１５）和（２０５）衍射峰或（１２１０）和（２０１０）衍射峰是重叠的，对生成的贝氏体进行一段时间的保温或缓慢冷却处理，其衍射峰的特征并不改变，这与马氏体（１１５）和（２０５）衍射峰或（１２１０）和（２０１０）衍射峰的分离特性不相符合。说明贝氏体结构有序度与马氏体明显不同，它的形成不可能继承母相的有序度。     

Flammability and thermal stability studies of ABS/Montmorillonite nanocomposite

Acrylonitrile–butadiene–styrene (ABS)/montmorillonite nanocomposites have been prepared using a direct melt intercalation technique by blending ABS and organophilic clay of two different particle sizes: OMTa (5 µm) and OMTb (38 µm). Their structure and flammability properties were characterized by X‐ray diffraction, high resolution electronic microscopy (HREM), thermogravimetric analysis (TGA) and cone calorimeter experiments. The results of HREM showed that ABS/5 wt% OMTa nanocomposite was a kind of intercalated–delaminated structure, while ABS/5 wt% OMTb nanocomposite was mainly an intercalated structure. The nanocomposites showed a lower heat release rate peak and higher thermal stability than the original ABS by TGA and cone calorimeter experiments. Also, the intercalated nanocomposite was more effective than an exfoliated–intercalated nanocomposite in fire retardancy. Copyright © 2003 Society of Chemical Industry     

历史街区市政工程规划适应性研究与探索——以拉萨八廓街为例

历史街区保护是我国现阶段历史文化遗产保护制度的重心所在,现有的部分工程技术手段容易导致因改善市政基础设施而破坏历史街区的真实性,影响历史街区人文和景观风貌.结合工程案例,展开了针对历史街区市政基础设施改造规划的适应性研究与创新性实践探索,在历史街区改造的受限条件下,采用最小化的精准改造方案,有效地解决了八廓街面临的供排水和工程管线综合布置等问题,为历史街区居民及其建筑文化遗产的生存和可持续发展提供技术支撑.     

新型气动溢流阀及其动态特性的仿真分析

本文在介绍一种新型气动溢流阀的基础上,运用计算机仿真技术研究该阀的动态特性,建立了气动溢流阀的基本动态微分方程,采用数值方法求解方程,并把仿真结果用于指导气动溢流阀的设计,得到了满意的效果。     

ON THE CALCULATION OF DRIVING FORCE FOR MARTENSITE TRANSFORMATION AND M_s IN Fe-Ni-C ALLOYS

选取了三种不同的热力学模型,(1)LFG模型;(2)徐祖耀三元系规则溶液模型;(3)本文处理方法(Fisher-徐模型加Zener参数),计算了Fe-Ni-C合金马氏体相变驱动力,求得马氏体相变驱动力与奥氏体在Ms温度的固溶强化呈线性关系:△G~(a→)M=Aσ_(0.2)(Ms)+908J/mol,对不同模型选取系数A’略有差异.利用所导出的奥氏体在Ms温度时的屈服强度,计算了Fe-Ni-C合金的MS温度,计算结果与以往的实验值符合得很好。     

PREPARATION OF TiN FILMS BY N_2 ASSISTED Xe~+ ION BEAM ENHANCED DEPOSITION AND THEIR MECHANICAL PROPERTIES

A new method for preparation of hard TiN films has been developed by using electronbeam evaporation-deposition of Ti and bombardment with 40 keV Xe~+ ion beam ina N_2 gas environment.The synthesized TiN films were superior to PVD and CVDones in respects of improved adhesion to substrate and low preparing temperature.Theyexhibited good wear resistance and high hardness up to 2200 kg/mm~2.Some industrialapplications have been reported.     

THERMODYNAMICS OF BAINITIC TRANSFORMATION IN Cu-24 at.-% Al ALLOY

Two driving forces △G~((β_1)+α')and △G~(β_1→β_2+α)for the bainitic transformation have been calcu-lated for Cu-24 at.-% Al alloy.Results reveal △G~(β_1→α')>0 within the transformation tem-perature range 600—750 K.Therefore,the bainitic transformation cannot be initiated by theβ_1→α' shearing mechanism.On the other hand,the driving force △G~(β_1→β_2+α)to produce 5% ofthe α becomes negative only when the composition of the α satisfiesx_(Al)~α≤0.204 at 700 K or x_(Al)~α=0.209 at 750 K.So the bainitic transformation can only proceedby β_1→β_2+α diffusional reaction with different diffusion amount at different temperatures.     

DIFFUSION OF CARBON DURING FORMATION OF LOW-CARBON MARTENSITE (Continued)

计算得到低碳马氏体形成时使残余奥氏体富碳所需扩散的时间约为7×10~(-3)—3×10~(-4)s。与条状马氏体形成的时间——10~(-3)—10~(-6)s比较,可见碳的扩散跟得上或稍落后于马氏体条的形成。残余奥氏体均匀富碳的时间落后于马氏体条的形成至少达1个数量级。这些表明低碳马氏体形成时可能存在碳的扩散,但后者不是马氏体相变的主要或必需过程。若低碳马氏体按上贝氏体形式长大,则计算所得其长大速率仅3×10~(-4)cm/s,比现有实验数据至少低2个数量级。本文工作再次证明低碳马氏体的形成机制和上贝氏体的不同。