Synthesis of C_f/TiAl_3 Composite by Infiltration-In Situ Reaction

Infiltration-in situ reaction synthesis of Cf /TiAl3 composite was investigated. The as-cast material was obtained by titanium particles, carbon fibers and pure aluminum. Titanium particles and carbon fibers were mixed and pressed to form a preform firstly, and then molten pure aluminum was pressed into the preform, subsequently, cooled rapidly. In situ reaction samples were obtained by heating the as-cast material from 600 to 1000 °C for 1 h. The microstructural evolution of in situ reaction samples was an...     

PA6／碳纳米管复合材料的复合方法的研究

ＣＶＤ法生产的碳纳米管经处理后呈纳米级分散，且表面产生大量的－ＯＨ官能团。碳纳米管与ＰＡ６（尼龙６）复合时，将通过其表面的－ＯＨ参加ＰＡ６的聚合反应，并阻碍ＰＡ６分子链的长大，削弱基体的强度。选择适当的复合方法，在尽量减少碳纳米管对ＰＡ６分子长大阻碍的基础上，改善碳纳米管在基体ＰＡ６中的分散，并进行后处理，可获得机能性能较好的ＰＡ６／碳纳米管复合材料。     

硅烷偶联剂KH550对超细石英粉的改性

采用γ-氨丙基三乙氧基硅烷(KH550)对超细石英粉进行表面改性。探索最佳的改性条件,并对改性后的超细石英粉进行傅里叶变换红外光谱(FTIR)、X射线光电子能谱(XPS)和Zeta电位的表征,分析计算了改性前后超细石英的粒度分布和表面羟基数变化。结果表明,KH550添加量为1.6%、反应时间为8h、反应温度为120℃时,对超细石英粉改性效果最佳;超细石英粉在改性前后表面羟基数由原来的1.74个/nm2减少到0.42个/nm2,疏水性提高;改性后超细石英Zeta电位绝对值较改性前提高,通过粒度分析,改性后超细石英粉细粒级含量增多,颗粒分散性提高;FTIR和XPS表明KH550在超细石英粉表面附着良好,为化学吸附,改性效果明显。     

全层片状TiAl基合金断裂过程的原位观察

利用ＳＥＭ拉伸台，研究了Ｔｉ－３３Ａｌ－３Ｃｒ－０．５Ｍｏ合金的室温拉伸断裂动态过程。试验结果表明，具有全层片状显微组织的ＴｉＡｌ合金室温断裂韧性较高，归因于合金拉伸过程中裂纹尖端发生分叉致使应力松弛而使裂纹钝化；在变形过程中，主裂纹尖端附近的微裂纹之间形成剪切韧带，剪切韧带韧化是ＴｉＡｌ合金的一种韧化机理。     

The Influence of Glow and Afterglow Cold Plasma Treatment on Biochemistry,Morphology, and Physiology of Wheat Seeds

Cold plasma (CP) technology is a technique used to change chemical and morphological characteristics of the surface of various materials. It is a newly emerging technology in agriculture used for seed treatment with the potential of improving seed germination and yield of crops. Wheat seeds were treated with glow (direct) or afterglow (indirect) low-pressure radio-frequency oxygen plasma. Chemical characteristics of the seed surface were evaluated by XPS and FTIR analysis, changes in the morphology of the seed pericarp were analysed by SEM and AFM, and physiological characteristics of the seedlings were determined by germination tests, growth studies, and the evaluation of α-amylase activity. Changes in seed wettability were also studied, mainly in correlation with functionalization of the seed surface and oxidation of lipid molecules. Only prolonged direct CP treatment resulted in altered morphology of the seed pericarp and increased its roughness. The degree of functionalization is more evident in direct compared to indirect CP treatment. CP treatment slowed the germination of seedlings, decreased the activity of α-amylase in seeds after imbibition, and affected the root system of seedlings.     

龙滩碾压混凝土室内外抗剪试验结果对比分析

对龙滩大坝碾压混凝土的室内抗剪、现场原位抗剪试验和芯样抗剪试验结果进行了对比分析。室内和现场抗剪试验结果表明,随着层面间歇时间的延长,3种强度等级的碾压混凝土的抗剪强度均下降,尤其是冷缝出现后抗剪强度最低。采用小值平均法和保证率为80%时统计法分析,3种强度等级的碾压混凝土现场原位抗剪试验的f′、c′值均能满足设计要求,小值法较统计法的f′值稍高,c′值稍低;分别用小值法和统计法得出的f′、c′值计算出的抗剪强度差别不大,小值法稍低。除去尺寸效应和龄期的影响后,两种强度等级的芯样抗剪强度均大于设计抗剪强度。     

新疆叶尔羌河中游渠首工程地基处理设计

叶尔羌河洪水动态规律极为复杂,以其极高的起涨速率、异常的高洪峰值闻名于世。中游渠首地基是粘粒极少、极松散的粉细沙层。针对其特点,采用振冲挤密砂石桩、防渗防冲连续墙、抗冲柔性土工布金属网格石笼等综合处理措施进行设计。     

自主知识产权产品LIP封装

为解决QFN成本较高的问题和进一步提高产品可靠性,华天科技突破了传统思想的束缚,在产品结构的设计上进行了创新。引脚在封装本体内式封装(LIP:Lead In Package)是一种新型的封装形式,它是针对目前QFN(Quad Flat No-lead)在封装高成本问题而重新选择的设计方案。     

铜掺杂多孔硅的光致发光及其载流子的复合过程

采用浸泡镀敷的方法在多孔硅表面形成了一镀铜层,通过对掺铜前后多孔硅的光致发光(PL)谱和傅里叶变换红外(FTIR)吸收光谱的研究,讨论了铜在多孔硅表面的吸附对其光致发光的影响。实验表明,掺铜多孔硅的光致发光谱出现两个发光带,其中能量较低的发光带随主发光带变化,并使多孔硅的发光峰位蓝移。多孔硅发光峰位的蓝移,是由于在发生金属淀积的同时伴随着多孔硅表面Si的氧化过程(纳米Si氧化为SiO2)的缘故。