可再分散乳胶粉对硫铁矿尾砂自流平砂浆性能的影响

探究硫铁尾矿砂在自流平砂浆的资源化利用途径,以硫铁矿尾砂为细集料制备水泥基自流平砂浆,分析了可再分散乳胶粉掺量对砂浆流动度、力学性能及耐磨性的影响。结果表明：乳胶粉掺量可以显著降低20 min、60 min 后的流动度经时损失,乳胶粉掺量为2.0%时,砂浆的拉伸粘结强度为1.9 MPa,并在天然河砂与尾砂复配情况下,尾砂替代率为75%时,磨损量仅有0.09 kg/m2。     

反应介质对机械合成二硫化铁的动力学影响

分别在空气、无水乙醇和煤油3种介质下成功通过机械力化学法合成出FeS2,并作出了其合成过程的动力学曲线,并用费尔哈斯模型进行拟合,计算了不同介质下机械合成FeS2的反应速度常数。通过对比3种介质下的动力学曲线和动力学参数可知:合成过程是先生成白铁矿,再由白铁矿转变为黄铁矿的同时,铁粉和硫粉逐渐反应生成黄铁矿。3种介质对合成过程都有不同程度的影响,其中无水乙醇环境更有利于黄铁矿的机械力化学合成,空气环境次之,煤油环境最差。     

On the Mechanistic Understanding of Photovoltage Loss in Iron Pyrite Solar Cells

Considering the natural abundance, the optoelectronic properties, and the electricity production cost, iron pyrite (FeS₂) has a strong appeal as a solar cell material. The maximum conversion efficiency of FeS₂ solar cells demonstrated to date, however, is below 3%, which is significantly below the theoretical efficiency limit of 25%. This poor conversion efficiency is mainly the result of the poor photovoltage, which has never exceeded 0.2 V with a device having appreciable photocurrent. Several studies have explored the origin of the low photovoltage in FeS₂ solar cells, and have improved understanding of the photovoltage loss mechanisms. Fermi level pinning, surface inversion, ionization of bulk donor states, and photocarrier loss have been suggested as the underlying reasons for the photovoltage loss in FeS₂. Given the past and more recent scientific data, together with contradictory results to some extent, it is timely to discuss these mechanisms to give an updated view of the present status and remaining challenges. Herein, the current understanding of the origin of low photovoltage in FeS₂ solar cells is critically reviewed, preceded by a succinct discussion on the electronic structure and optoelectronic properties. Finally, suggestions of a few research directions are also presented.     

硫化温度对FeS2薄膜的晶体结构和光电性能的影响

本文用磁控溅射法制备的纯Ｆｅ 膜,再在Ｓ气氛中（８０ｋＰａ）于不同的温度下（２００～６００℃）进行热硫化,硫化时间为１０ｈ,使其转变成为ＦｅＳ２薄膜,并研究了硫化温度对转变形成的ＦｅＳ２薄膜晶体结构、化学成分、组织形貌和光电性能的影响规律。     

稀相气-固流化床分选电厂磨机返料中黄铁矿的实验与模拟

为了降低燃煤电厂的磨机功耗,减少锅炉燃烧后的污染排放,通过分析磨煤机分离器返料的粒度和密度分布,对电厂采样物料进行稀相流化床分选去除黄铁矿等矿物质的实验研究,并对物料分选过程进行数值模拟。结果表明,粒径小于0.500 mm的分离器返料在流化床中具有较小的起始流化速度1.62 cm/s,流化床各层的密度和粒度具有很好的稳定性;物料中的黄铁矿等矿物质得到分离,上层和底层物料灰分质量分数分别为33.34%、73.42%,硫分质量分数分别为1.12%、8.96%,底层物中硫主要以黄铁矿的形式存在;气-固两相流稀相分选床的流场形态及颗粒运动数值模拟验证了实验结论。     

土石坝的爆破地震安全评估

根据坝体建立模型,通过模态分析得到大坝的固有频率。然后将开挖爆破时的现场爆破地震测量数据输入到模型中进行坝体的动力学行为仿真计算,得到了坝体内部的受力情况,在此基础上对土石大坝的安全状况进行了分析和评估。     

火焰原子吸收分光光度法测定碳素钢中铜含量的测量不确定度评定

对火焰原子吸收分光光度法测定碳素钢中铜含量的测量不确定度进行了分析,分析了测量不确定度的主要来源,并对各不确定度分量进行了评定,求得合成标准不确定度和扩展不确定度分别为0.00071%和0.0014%.     

Proving the existence of nanobubbles produced by hydrodynamic cavitation and their significant effects in powder flotation

Selective attachment of nanobubles (NBs) generated in different conditions on the surface of valuable minerals during flotation separation was a challenge that needs to be addressed. This investigation filled this gap and proved the existence of NBs on the target mineral's surface and their selective effectiveness through the process. The bubble size analysis results showed that the mean diameter of bubbles was between 60 and 70 nm; thus, they could be correctly called “nanobubbles”. Flotation test results showed a significant increase in the flotation recovery (by 37%) and grade (more than 1%) of fine phosphate ore sample (d₈₀: 37 µm) using NBs that generated in the presence of collector. Interestingly, surface analyses of flotation products showed that the amounts of flotation collector adsorbed onto the surface of floated particles was decreased in the presence of NBs compared with their absence. The change in the particle surface (zeta) potential in the presence of NBs also provides additional evidence of NBs “adsorbed” (i.e., the surface NBs) onto the particle surface. These results indicated that NBs produced by hydrodynamic cavitation could adsorb onto the target mineral particles. This adsorption could change their surface properties, improve their hydrophobicity and surface potentials, and enhanced the bubble-particle attachment in flotation.     

添加剂对水热法制备超细氧化铁的影响

以硫铁矿烧渣酸浸液为原料，采用水热法制备超细氧化铁。添加剂对水热产物的物相影响较小，但对水热产物形貌影响较大。当水热反应温度为190℃、反应时间为30min、总铁浓度为3mol／L、n（Fe^2＋）/n（Fe^3＋）取0．145时，加入添加剂CTAB、NaH2PO4、CO（NH2）2水热反应所得产物为椭球形粒子；加入PVP、OP所得水热产物为球形氧化铁粒子，但其粒径差异较大。酸浸液中n（Fe^2＋）／n（Fe^3＋）物质量之比对水热产物物相和形貌有重要影响。当n（Fe^2＋）/n（Fe^3＋）为0时，水热产物为大小均匀的球形超细Fe2O3粒子，其粒径约为0.11μm；当n（Fe^2＋）／n（Fe^3＋）为0．145时，其水热产物颗粒增大、粒径各异，物相为Fe2O3、Fe3O4；当n（Fe^2＋）/n（Fe^3＋）为0.842时，从放大3万倍SEM照片，难以观测其形貌与粒径大小，其物相为Fe3O4。     

铜管显微维氏硬度测定结果的不确定度评定

依据GB/T 4340.1—2009对某铜管进行了显微维氏硬度测试,并对显微维氏硬度测定结果的不确定度进行了评定。结果表明:当置信概率取95%时,该铜管的显微维氏硬度的测定结果为(86.5±2.8)HV0.1,k=2。     

Evaluation of the Three-Dimensional Region Around a Crack Tip by Caustics

A study of the extent of the three-dimensional region around the border of a straight through-crack in mode-I loading was undertaken by the method of caustics. A series of experiments were performed in single edge-notched specimens made of PMMA (Plexiglas). It was found that the state of stress very close to the crack tip can be approximated as plane strain. Following this region, three-dimensional stress conditions hold in the neighborhood of the crack tip, up to a critical distance which depends on the thickness of the plate and the crack length. Beyond this critical distance plane stress conditions dominate. Results were obtained for the extent of the three-dimensional region as a function of the specimen thickness. The present investigation illuminates the complicated problem of the changing state of stress around cracks and establishes the limits of applicability of the method of caustics for the determination of stress intensity factors. This revised version was published online in July 2006 with corrections to the Cover Date.     

景洪水电站右冲沙底孔坝段在爆破震动效应下的安全评价

利用ANSYS软件对景洪水电站右冲沙底孔坝段在爆破开挖条件下进行动、静分析,并将时程法引入到承载能力极限状态设计分析方法中,进行稳定验算.结果表明爆破地震效应对右冲沙底孔坝段的抗滑稳定有较大的影响,但不会危及坝段的整体稳定,并根据计算结果确定各个爆破开挖阶段控制点的安全控制振速.     

原子吸收光谱法测定茶叶中铜的测量不确定度评定

通过对测定茶叶中铜含量的不确定度评定分析,找出引起不确定度产生的主要因素,评定确认由最小二乘法拟合校准标准曲线及测量重复性是影响结果的最主要因素,使用标准物质（标准储备液）及稀释过程引入的不确定度也应引起重视,此方法对类似的火焰原子吸收法测定样品中待测元素含量有借鉴和参考作用。     

火力发电厂凝汽器铜管的腐蚀与防护

介绍了火力发电厂凝汽器铜管在使用寿命期间的腐蚀状况,指出黄铜管的腐蚀主要表现为脱锌腐蚀、应力腐蚀开裂和冲蚀等,分析讨论了其各自的腐蚀机理及相应的控制措施,介绍了铜管主要保护方法--硫酸亚铁成膜技术,对控制电厂铜管腐蚀提供一定的参考.     

Evaluation of grain refiners influence on the mechanical properties in a CuAlBe shape memory alloy by ultrasonic and mechanical tensile testing

This work carried out a non-destructive evaluation of grain size influence on the mechanical properties of a CuAlBe shape memory alloy with and without grain refiners. Ultrasonic signal processing, considering only the longitudinal velocity, was used for the non-destructive evaluation. Therefore, the average modulus of elasticity values found for the CuAlBe shape memory alloy was 45.7 GPa and 57.3 GPa with and without grain refiners, respectively. The corresponding values obtained by conventional mechanical tensile testing were equal to 43.2 GPa and 52.6 GPa, respectively. Additionally the mechanical tensile testing verified that the addition of grain refiners increases the stress of the alloy but has a slight effect on the alloy’s ductility. Thus, the modulus of elasticity and consequently the ultrasonic velocity, as well as the stress and strain values of CuAlBe alloy are fully dependent on its grain size. The ultrasonic analysis shows that this alloy is an excellent sound, vibration and mechanical wave absorber, presenting a high attenuation coefficient related to the wave scattering through the grains. In addition, the ultrasonic signal processing method used here confirms its main advantages of fastness and reliability.     

铜精矿中铁含量测定的不确定度评定

用重铬酸钾滴定法测定铜精矿中铁的含量,对其测量不确定度进行评定,分析了在整个实验过程中的不确定度来源,其主要来源有重铬酸钾标准溶液的浓度,滴定体积,试样称量以及重复性实验等.对各部分不确定度分量进行了量化计算,得出了合成标准不确定度,扩展不确定度,并以不确定度的形式给出测定结果.     

X荧光能谱法测定黄铜中的铜

通过对黄铜标样及样品的测试,建立了X荧光能谱仪测定黄铜中铜含量的方法。本方法采用能谱仪中定量分析软件;选择适当工作条件,测定黄铜中钢元素。其准确度,精密度,均能满足分析要求。     

Evaluation of dynamic development of grain structure during friction stir welding of pure copper using a quasi in situ method

By employing a quasi in situ method, we investigated the dynamic evolution of the grain structure considering the material flow, strain, and strain rate in the friction stir welding of pure copper. The tool ‘stop action’ and rapid cooling were employed and a brass foil was used as a marker to show the material flow path. The grain structure along the material flow path was characterised using electron backscatter diffraction. Static recrystallization occurs for the work-hardened base material in the preheating stage in front of the tool. In the acceleration flow stage, grains are significantly refined by plastic deformation, discontinuous dynamic recrystallization, annealing twinning during the strain-induced boundary migration and slight continuous dynamic recrystallization. In the deceleration flow stage, due to a strain reversal, the grain first coarsens, and is thereafter refined again. Finally, the hot-deformed material in the shoulder-affected zone is ‘frozen’ directly whereas that in the probe-affected zone undergoes significant annealing; thus, the recrystallized microstructure and 45°-rotated cube texture are obtained in the probe-affected zone.