Effect of graphite powder as a forming filler on the mechanical properties of SiCp/Al composites by pressure infiltration

(38vol% SiCp + 2vol% Al₂O_3f)/2024 Al composites were fabricated by pressure infiltration. Graphite powder was introduced as a forming filler in preform preparation, and the effects of the powder size on the microstructures and mechanical properties of the final composites were investigated. The results showed that the composite with 15 μm graphite powder as a forming filler had the maximum tensile strength of 506 MPa, maximum yield strength of 489 MPa, and maximum elongation of 1.2%, which decreased to 490 MPa, 430 MPa, and 0.4%, respectively, on increasing the graphite powder size from 15 to 60 μm. The composite with 60 μm graphite powder showed the highest elastic modulus, and the value decreased from 129 to 113 GPa on decreasing the graphite powder size from 60 to 15 μm. The differences between these properties are related to the different microstructures of the corresponding composites, which determine their failure modes.     

漂浮型光催化剂制备及其除藻性能初探

以膨胀石墨为载体,蔗糖为外覆炭层前驱物,采用溶胶-炭化一步制备膨胀石墨复合炭基氮、磷共掺杂二氧化钛复合材料(NPT-EGC),通过场发射扫描电子显微镜(FESEM)、氮吸附比表面积及孔容孔径分析仪(BET)、X射线衍射仪(XRD)、紫外-可见漫反射光谱仪(UV-vis DRS)、X射线光电能谱仪(XPS)和傅里叶变换红外光谱仪(FT-IR)等分析手段进行材料表征,考察不同煅烧温度制备的材料的除藻性能.实验结果表明,NPT-EGC复合材料具有蠕虫状的空间结构,表面覆有均匀的二氧化钛颗粒.氮、磷以掺杂的方式进入二氧化钛晶格,其中氮主要通过取代氧的方式,而磷主要通过取代钛的方式.掺杂后复合材料的光能吸收率明显提高.考察不同煅烧温度下制备的NPT-EGC材料对铜绿微囊藻的去除性能发现,相对于无催化剂和无光催化负载的情况,复合材料NPT-EGC的除藻性能有明显提高,其中以450℃下制备的NPT-EGC除藻效果最好,9h的藻细胞去除率在98%以上.另外,漂浮型的材料易被分离回收,更有利于光能转化,在环境污染治理中应用前景广阔.     

电火花线切割断丝特征及断丝预报的研究

研究了电火花线切割加工中出现断丝时的先兆特征，提出了独特的判别指标．在此基础上应用神经网络理论中的遗传－ＢＰ算法来预报非正常断丝的出现，并用加工过程中采集到的数据对系统进行了验证．     

2∶18-硫钼杂多阴离子修饰电极电化学和电催化研究

以玻碳（ＧＣ）电极为基体制备２∶１８－硫钼杂多阴离子薄膜修饰电极（简称Ｓ２Ｍｏ１８修饰电极），并探讨了其电化学行为和电催化性能为杂多酸催化体系在电化学特别是电催化方面的研究和应用提供新的方法     

STUDEIS ON THE CMD OBTAINED FROM OXIDIZING MnO 2 BY KClO 3

为了弥补干电池材料电解ＭｎＯ２（简称ＥＭＤ）的某些性能上的不足，以期用化学ＭｎＯ２（简称ＣＭＤ）替代．在一定条件下，以氯酸钾氧化Ｍｎ２＋沉积法制化学ＭｎＯ２，对其进行ＭｎＯ２含量、肼脂数、磁化率、放电性能以及红外与差热等分析．结果表明，制得的ＣＭＤ电化活性较高，有望替代电解ＭｎＯ２作为干电池的阴极活性材料     

无机含氧酸氧化性强弱递变规律的探讨

多氧化态成酸元素它们的最高氧化态的含氧醚和Ｎ，Ｓ，Ｃｌ的最高氧化态的含氧酸ＨＮＯ３，Ｈ２ＳＯ４和ＨＣｌＯ４等都有较强的氧化性。本文将对无机含氧酸氧化性强弱递变的规律进行探讨并分析其影响因素。     

Pt/YSZ电极烧制温度对其性能的影响

采用交流阻抗测试技术、循环伏安、计时电流和扫描电镜等实验方法,研究了Pt/YSZ电极烧制温度对其性能的影响.研究表明,随着烧制温度升高,电极过程激活能减小,电极总阻抗和响应时间均先减小后增大.烧制温度小于或等于1100℃时,氧原子大量吸附于Pt电极表面,与铂原子发生位置重排反应而生成Pt氧化物,电极过程激活能为177～230 kJ.mol-1;烧制温度大于1100℃时,电极系统中可能存在的Pt氧化物充分解离,电极过程激活能为107～172 kJ.mol-1.烧制温度为1000～1100℃所制电极总阻抗最小,电荷转移过程响应最快,电极活性最高.     

聚吡咯修饰电极应用的研究

制备了经碱的掺铁氰根聚吡咯修饰电极,发现此电极对多巴胺有较强的选择性富集作用,由此建立了多巴胺新的分析方法,实验表明,过量的抗坏血酸（AH2）不干扰多巴胺的测定,该法用于测定多巴胺,获得了满意的结果。     

Preparation and characterization of LiAlxMn2-xO4 for a supercapacitor in aqueous electrolyte

LiAl_xMn_2—xO₄ (0≤x≤0.5) was synthesized by high temperature solid-state reaction. The structure and morphology of LiAl_xMn_2—xO₄ were investigated by X-ray diffraction and scanning electron microscopy (SEM). The results indicate that all samples show spinel phase. The polyhedral particles turn to club-shaped, then change to small spherical, and finally become agglomerates with increasing Al content. The supercapacitive performances of LiAl_xMn_2—xO₄ were studied by means of galvanostatic charge-discharge, cyclic voltammetry, and alternating current (AC) impedance in 2 mol·L⁻¹ (NH₄)₂SO₄ aqueous solution. The results show that LiAl_xMn_2—xO₄ represents rectangular shape performance in the potential range of 0-1 V. The capacity and cycle performance can be improved by doping Al. The composition of x=0.1 has the maximum special capacitance of 160 F·g⁻¹, which is 1.37 times that of LiMn₂O₄ electrode. The capacitance loss of LiAl_xMn_2—xO₄ with x=0.1 is only about 14% after 100 cycles.     

Growth of graphite film over the tops of vertical carbon nanotubes using Ni/Ti/Si substrate

A substrate with Ni/Ti/Si structure was used to grow vertical carbon nanotubes (CNTs) with a graphite fihn over CNT tops by thermal chemical vapor deposition with CH₄ gas as carbon source. The carbon nanotubes and the substrate were characterized by a field emission scanning electron microscope for the morphologies, a transmission electron microscope for the microstructures, a Raman spectrograph for the ctystallinity, and an Auger electron spectrometer for the depth distribution of elements. The result shows that when the thickness ratio of Ni layer to Ti layer in substrate is about 1, a graphite film with relatively good quality can be formed on the CNT tops.