碳包覆对LiMn_(0.5)Fe_(0.5)PO_4/C复合材料形貌的影响

本文采用流变相法合成了碳包覆改性的LiMn_(0.5)Fe_(0.5)PO_4/C锂离子电池正极材料。通过X射线衍射(XRD)、扫描电镜(SEM)等手段,比较和分析了柠檬酸、酒石酸、月桂酸三种碳源对材料结构、形貌的影响。结果表明,以柠檬酸为碳源合成的LiMn_(0.5)Fe_(0.5)PO_4/C是由一次颗粒极小的纳米粒子组成的微纳结构聚集体,具有极高达48.32m2g-1的比表面积。     

Nb掺杂对Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)Nb_xO_3(0≤x≤0.15)阴极材料电化学性能影响的研究

为了研究Nb掺杂对于Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_3阴极材料的电化学性能的影响,采用燃烧法合成了Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2-x) Nb_xO_3(BSCFN_x,x=0、0.05、0.1、0.15),并将其作为固体氧化物燃料电池(solid oxide fuel cell,SOFC)阴极材料进行性能测试。XRD结果显示,所有Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2-x)Nb_xO_3样品均为立方型钙钛矿相,没有杂质出现。电导率测试结果显示,随着Nb含量的增加,BSCFN_x的电导率和电化学输出性能均随之先上升、后下降,Nb的最佳掺杂比例为Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.1)Nb_(0.1)O_3(BSCFN0.1)。在800℃下,BSCFN0.1的电导率高达36.3S/m。在700℃下,以BSCFN0.1为阴极的氧化钆掺杂的氧化铈(Ce_(0.9)Gd_(0.1)O_2GDC)为电解质支撑单电池的最大功率密度可以达到194 mW/cm~2,比其他Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2-x)Nb_xO_3(x=0、0.05、0.15)阴极基GDC电解质支撑的单电池最大功率密度明显增大。功率密度测试结果与电导率测试结果相一致,说明Nb的掺杂对于提高BSCF的电导率以及氧化还原反应(oxygen reduction reaction,ORR)催化性能具有显著效果,且当x=0.01时为最佳。     

碳包覆改性对LiMn_(0.5)Fe_(0.5)PO_4/C复合材料电性能的影响

本文比较和分析了柠檬酸、酒石酸、月桂酸三种碳源对LiMn_(0.5)Fe_(0.5)PO_4/C材料电化学性能的影响。采用流变相法合成,通过恒流充放电测试等手段分析,结果表明,以柠檬酸为碳源合成的LiMn_(0.5)Fe_(0.5)PO_4/C表现出优异的倍率性能和循环性能。     

La_(0.5)Ca_(0.5)MnO_3钙钛矿微晶的NH_4~+辅助水热合成及晶面调控

为了研究特殊晶面与晶体材料的物理性质的关系,需要合成具有特殊晶面的晶体。采用水热法,通过调节反应过程中温度、尿素和KOH的质量,合成了具有不同形状和晶面的La_(0.5)Ca_(0.5)MnO_3钙钛矿微晶。利用X射线衍射仪、扫描电子显微镜对晶体的形貌、结构进行了表征,比较了不同温度、不同尿素和KOH质量对产物结构和形状等的影响,并对反应机理进行了研究。提出了制备八面体形状La_(0.5)Ca_(0.5)MnO_3微晶的最优方案,即温度为260℃、尿素质量为2.25g,且KOH质量为9g。为研究特殊晶面与材料的物化性质和材料的构效关系提供了依据。     

B_2O_3包覆锂离子电池正极材料LiNi_(0.5)Mn_(1.5)O_4的制备及性能研究

该文以工业原料合成B_2O_3包覆正极材料LiNi_(0.5)Mn_(1.5)O_4。通过放电曲线可知,在小倍率下(0.5C,1C),包覆0.5%B_2O_3的正极材料具有最好的放电性能;在大倍率(5C,7C,10C)下,包覆1%B_2O_3的LiNi_(0.5)Mn_(1.5)O_4正极材料具有最好的放电性能。     

Ce掺杂LaMnO_3/PS-FLG催化剂低温脱硝性能研究

以农业废弃物花生壳衍生少层石墨烯(PS-FLG)为载体,采用水热法制备负载型催化剂,对其NH_3-SCR脱硝性能进行了测试。通过XRD,FTIR,SEM等测试手段初步探明了活性组分Ce在A位进行掺杂增强催化活性的内在机制。结果表明,在250℃-350℃时催化剂活性都能达到90%以上并保持稳定,且催化剂5%La_(0.5)Ce_(0.5)MnO_3/PS-FLG表现出最好的低温催化活性。金属氧化物更均匀地分散在少层石墨烯表面,使其表现出更好的脱硝活性。     

爆炸焊制备Al_2O_3/Cu-QCr0.5复合板工艺及性能

用内氧化法制备Al2O3/Cu粉,将Al2O3/Cu粉进行真空热压烧结,得到Al2O3/Cu板,然后采用爆炸焊法制备了Al2O3/Cu-QCr0.5复合板,并对复合板界面性能进行了研究。研究结果表明:在1 000℃,压力为4MPa的条件下,经3 h真空热压烧结制备Al2O3质量分数分别为1.0%和0.5%的Al2O3/Cu板,采用爆炸焊方法能够与QCr0.5结合制备出质量良好的Al2O3/Cu-QCr0.5复合板,且Al2O3质量分数为1.0%的Al2O3/CuQCr0.5复合板结合质量较好;结合界面硬度介于Al2O3/Cu基体和QCr0.5基体之间;爆炸参数不同会引起漩涡、周边打伤、打裂等问题;受爆炸冲击作用,在结合面处晶粒变形最大,较远位置处变形微小。     

锂离子电池性能测试防爆箱的安全性设计

选取50 Ah的圆柱形空间锂离子电池作为研究对象,选择耐火砖、Q420钢、钢筋混凝土作为防爆箱箱体材料,对锂离子电池进行过充过放循环试验和短路试验,直至发生燃烧和爆炸,观测箱体材料的变化情况。通过理论计算确定防爆箱的尺寸为0.4 m×0.5 m×0.5 m。根据实验结果确定防爆箱箱体材料选择高铝隔热轻质耐火砖,外衬1.6 cm厚的Q420钢。同时配置相应的消防和报警设施,为50 Ah的圆柱形空间锂离子电池设计了一种安全可靠的性能测试防爆箱。     

烧结升温速率对(Na_(0.5)Bi_(0.5))_(0.94)Ba_(0.06)TiO_3无铅陶瓷的结构和电学性能的影响

采用传统固相反应法制备了(Na0.5Bi0.5)0.94Ba0.06TiO3无铅压电陶瓷,在烧结过程中采用了不同的升温速率(0.5、1、3、5℃/min),研究了烧结升温速率对陶瓷试样的相结构、显微结构、压电性能、介电性能和铁电性能的影响。结果表明,所有陶瓷试样均形成了纯钙钛矿结构;随着烧结升温速率增大,陶瓷的晶粒尺寸减小;陶瓷试样的居里温度和最大介电常数随烧结升温速率的增大均减小;所有陶瓷试样均呈现弥散相变特征;烧结升温速率增大引起陶瓷试样的最大极化强度和剩余极化强度增大,矫顽场减小,压电常数增大。     

1.25Cr-0.5Mo-Si焦炭塔的制造

通过对1.25Cr-0.5Mo-Si钢焊接性的分析,选用合适的焊材和焊接工艺,并在焊接工艺评定和实际生产中证明其能满足设计条件和设备制造的需要。     

Removal of As(III) and As(V) from water using a natural Fe and Mn enriched sample

The arsenic removal capacity of a natural oxide sample consisting basically of Mn-minerals (birnessite, cryptomelane, todorokite), and Fe-oxides (goethite, hematite), collected in the Iron Quadrangle mineral province in Minas Gerais, Brazil, has been investigated. As-spiked tap water and an As-rich mining effluent with As-concentrations from 100 μg L⁻¹ to 100 mg L⁻¹ were used for the experiments. Sorbent fractions of different particle sizes (<38 μm to 0.5 mm), including spherical material (diameter 2 mm), have been used. Batch and column experiments (pH values of 3.0, 5.5, and 8.5 for batch, and about pH 7.0 for column) demonstrated the high adsorption capacity of the material, with the sorption of As(III) being higher than that of As(V). At pH 3.0, the maximum uptake for As(V) and for As(III)-treated materials were 8.5 and 14.7 mg g⁻¹, respectively. The Mn-minerals promoted the oxidation of As(III) to As(V), for both sorbed and dissolved As-species. Column experiments with the cFeMn-c sample for an initial As-concentration of 100 μg L⁻¹ demonstrated a very efficient elimination of As(III), since the drinking water limit of 10 μg L⁻¹ was exceeded only after 7400 BV total throughput. The As-release from the loaded samples was below the limit established by the toxicity characteristic leaching procedure, thus making the spent material suitable for discharge in landfill deposits.     

Effect of varying cement content and curing conditions on the properties of sarooj (artificial pozzolana)

This paper describes research carried out at Sultan Qaboos University on the use of the local pozzolanic material, known as sarooj, with Portland cement. Sarooj was the major constituent and cement was used as an additive with various percentages, as used in restoration of historical monuments around the country. Seven mixes with the proportion of sarooj=1.0, sand=0.4, cement=0.2 and water=0.5 were cured for different durations in air and water to establish the best curing conditions suitable for the hot humid conditions of the Gulf region (28–45°C, R/H 60–80%). In addition, four groups of mixes (sarooj, sand, cement, water), each containing 11 mixes with cement content varying from 0 to 100% by mass of sarooj were tested to study the effect of varying the amount of cement on the strength characteristics. It was found that curing in the sun produced the highest strength results. The cement/sarooj ratio by mass was about 0.6.     

大同市0．5m分辨率真彩色数字正射影像图制作

指出数字正射影像是利用像控点和数字高程模型,对影像同时进行倾斜改正和投影差改正,之后经影像镶嵌和匀光匀色后裁切而成。以大同市0．5m分辨率真彩色数字正射影像图制作项目为例,介绍了大同市勘察测绘院数字正射影像图的生产制作经验,以供类似项目参考借鉴。     

基于磷酸镁水泥的植物茎秆增强混凝土试验研究

采用磷酸镁水泥(MPC)、粉煤灰和油菜茎秆制备新型绿色混凝土,探讨了该混凝土作为保温隔热墙体材料的可行性,并讨论了油菜茎秆的掺量和尺寸对混凝土性能的影响,测试了所制备的植物茎秆增强混凝土的表观密度、抗压强度和导热系数.结果表明:所制备的植物茎秆增强混凝土可以满足承重和非承重墙体材料的技术要求;油菜茎秆的多孔隙特征保证了该绿色混凝土具有优异的保温隔热特性;与硅酸盐水泥和石灰等其他胶凝材料相比,磷酸镁水泥更适宜制备植物茎秆增强混凝土.     

Leaching of antimony from polyethylene terephthalate (PET) bottles into mineral water

The Sb leaching from polyethylene terephthalate (PET) package material into 10 different brands of still (non-carbonated) and sparkling (carbonated) Hungarian mineral water purchased in supermarkets was investigated by inductively coupled plasma sector field mass spectrometry (ICP-SF-MS). The Sb concentration measured in PET package materials varied between 210 and 290 mg/kg. Generally, the Sb concentration of still mineral water was lower than that of sparkling in the case of identical storage time. For modelling improper storage conditions, storage time (10-950 days), temperature (22 °C-70 °C), illumination (dark vs. 23 W daylight lamp for 116 h) as well as bottle volume (0.5, 1.0 and 1.5 L) were taken into consideration. Under certain extreme light and temperature storage conditions, the Sb concentration of some samples exceeded the concentration value of 2 ng/mL. The extent of Sb leaching from the PET recipients of different brands of mineral water can differ by even one order of magnitude in experiments conducted under the same conditions. Thus, the adequate selection of the polymer used for the production of the PET bottle for the solar water disinfection (SODIS) procedure seems to ensure low Sb levels in the water samples.