不同变质剂对铝合金组织及性能的影响

在合金熔炼的过程中分别加入RE(镧铈混合稀土)、Al-Ti-B和铝钪合金对合金进行变质处理,研究不同变质剂对合金组织及力学性能的影响。结果表明,RE、Al-Ti-B和铝钪都是通过改变合金中硅相的颗粒大小来改变合金的铸态组织,从而提高合金的综合力学性能。     

弹性纵波在具有非线性法向变形本构关系的节理处的传播特征

对正向入射弹性纵波穿越岩石节理的过程及特性进行理论研究，所研究的岩石节理具有非线性法向变形本构关系。在没有剪切波的情况下，探讨节理的非线性法向变形行为对弹性纵波传播的影响。传统的有关应力波在节理处传播的线性位移不连续理论模型。发展为非线性模型-双曲模型（BB模型），依据此模型，获得了节理透射和反射系数的数值解。该数值解用来进行一系列的参数研究，包括节理初始刚度，节理闭合量相对于最大允许闭合量的比率以及入射波的振幅和频率对节理透射系数的影响等参数研究。也对线性和非线性位移不连续理论模型作了比较。结果表明，线性模型得到的透射和反射系数解是非线性解的一种特例，即当入射波的振幅很弱以至于在波传播中产生的最大节理闭合量相对于最大允许闭合量足够小的条件下，非线性与线性解等同，此外，还发现当波在节理处传播时，节理的非线性变形行为会引起一种高谐波现象。     

Effect of Cr doping on the structural,electrochemical properties of Li[Li0.2Ni0.2−x/2Mn0.6−x/2Crx]O2 (x = 0, 0.02, 0.04, 0.06, 0.08) as cathode materials for lithium secondary batteries

Prospective positive-electrode (cathode) materials for a lithium secondary battery, viz., Li[Li_0.2Ni_0.2−x/2Mn_0.6−x/2Cr_x]O₂ (x = 0, 0.02, 0.04, 0.06, 0.08), were synthesized using a solid-state pyrolysis method. The structural and electrochemical properties were examined by means of X-ray diffraction, cyclic voltammetry, SEM and charge–discharge tests. The results demonstrated that the powders maintain the α-NaFeO₂-type layered structure regardless of the chromium content in the range x ≤ 0.08. The Cr doping of x = 0.04 showed improved capacity and rate capability comparing to undoped Li[Li_0.2Ni_0.2Mn_0.6]O₂. ac impedance measurement showed that Cr-doped electrode has the lower impedance value during cycling. It is considered that the higher capacity and superior rate capability of Cr-doping samples would be ascribed to the reduced resistance of the electrode during cycling.     

毛细管波导流通池连续流动分析仪测定水中低浓度挥发酚

采用配有1m毛细管波导流通池的连续流动分析仪（CFA）测定了水中的低浓度挥发酚,探讨了方法的检出限、准确度、精密度和水样加标回收率。结果显示,仪器方法的检出限为0.11μg/L,考核样测定平均值为4.41μg/L,与标准值4.55±0.36μg/L吻合,相对标准偏差为0.79%。测定实际水样,加标回收率在96%～104%之间。本法检出限低,准确性好,精密度高,适合水中低浓度挥发酚的检测。     

增强树脂基无石棉闸瓦的摩擦性能分析

以矿用增强树脂基无石棉闸瓦工况条件及运行参数为背景,以酚醛树脂基复合材料闸瓦WSM–3为研究对象,选择名义接触压力P、滑动速度υ、接触面温度T为可调参数,考察三者与摩擦系数μ的关系。并通过3个可调参数的多种组合分析复合材料的摩擦学性能,实验结果表明单参数、双参数、三参数实验方法在分析摩擦系数变化的不同性质时各有利弊。建立组合参数与摩擦系数的关系对材料摩擦学设计具有重要意义,亦适用于其它材料的摩擦学性能实验。     

Synthesis and electrocatalytic alcohol oxidation performance of Pd–Co bimetallic nanoparticles supported on graphene

Magnetic Pd–Co bimetallic nanoparticles supported on reduced graphene oxide sheets (Pd–Co/RGO) with excellent electrocatalytic performance have been synthesized by a rapid reducing method, using sodium hypophosphite as the reducing agent. The loading and crystalline phase of cobalt in the Pd–Co/RGO hybrids varied as to the initial amount of cobalt salt and reducing agent. Transmission electron microscopy images show that the mean size of the Pd–Co bimetallic nanoparticles was about 10–13 nm and without significant agglomeration. At the same Pd loading on graphene, the current densities of the forward anodic peak of the different Pd–Co/RGO catalysts was decreased by about 25% when compared with that of the pure Pd nanoparticles supported on reduced graphene oxide for both methanol and ethanol oxidation. However, chronoamperometry tests confirmed that the stability was increased by up to 240% and 225% for methanol oxidation and ethanol oxidation, respectively. It is hypothesized that the Co layer on Pd partially blocks Pd sites sacrificing a small portion of the activity of the catalysts, but it leaves the remaining Pd more active and thus enhances alcohol oxidation kinetics and tolerance to poisoning intermediates. Catalytic performance of the Pd–Co/RGO hybrids for alcohol oxidation is primarily affected by the interaction among Pd, Co, and graphene.     

Formula One组件在建筑质量综合评定系统中的应用

通过建筑质量综合评定系统的开发实例，介绍了在Delphi开发平台下调用Formula One组件进行通用表数据处理的方法。