消融材料约束金属丝电爆法制备纳米粉

研制了一种用于制备纳米金属粉的丝电爆装置,通过改变初始充电电压对三种不同熔点材料进行电爆试验,并表征了所制备的纳米粉。结果表明,通过增加初始充电电压,可提高作用在金属丝上的能量密度,进而能减小所得纳米粉的平均粒径。当电压增加到一定程度时,粉体平均粒径处于一个相对稳定的值,制得铝、镍和钼纳米粉的平均粒径分别为31、33、42 nm。     

镍纳米粉物理法制备技术

通过高频热等离子体法和电爆炸丝法制备了镍纳米粉,利用X射线衍射(XRD)、透射电子显微镜(TEM)对制备的镍纳米粉的晶体结构、粒径大小和形貌进行表征,对两种方法制备的产物进行比较。结果表明,高频热等离子体法制备的镍纳米粉呈规则球形、分散性良好、平均粒径为63 nm,而电爆炸丝法制备的镍纳米粉有部分颗粒呈球形,部分颗粒呈正方体形状,分散性比等离子体法制备的镍粉更好,粒径更小,平均粒径为26 nm,但氧化比较严重。     

ATO纳米粉体的性能特点与制备研究现状

详细介绍了锑掺杂二氧化锡(ATO)纳米粉体良好的导电抗静电性能、浅色透明性、良好的耐候性和稳定性、纳米粒子特性、多功能性等性能特点,简述了ATO纳米粉体的应用领域;综述了目前制备ATO纳米粉体的固相法、水热法和化学共沉淀法等方法,对几类制备方法优缺点进行分析,进一步确定改进的化学共沉淀法和水热法制备ATO纳米粉体时的最佳实验条件.指出了目前ATO纳米粉体制备存在的几点问题,为进一步研究ATO纳米粉体的制备提供参考依据.     

乳浊液和均匀沉淀结合法制备球形纳米ZrO2(Y2O3)粉末

采用二甲苯为油相,span-80为表面活性剂,Zr(NO3)4(3Y)的水溶液为水相的W/O乳浊液和草酸二甲酯均匀沉淀结合法制备四方相ZrO2(3Y)纳米粉。用热重差热法、X射线衍射仪、透射电镜、比表面积分析等手段对粉末及其前驱体进行分析和表征。结果表明:采用乳浊液与均匀沉淀结合法所制得的ZrO2纳米粉具有产率高、球形和分散性好等特点。在制备过程中,锆盐溶液的浓度、水浴反应温度和草酸二甲酯的含量对产物的平均粒径具有规律性的影响。     

油幕电爆法对纳米铜粉分散性能的影响

利用自制的油幕电爆装置制备了纳米铜粉。以油酸作为分散剂对纳米铜粉进行分散,利用紫外-可见分光光度计(UV-Vis)、X射线衍射仪(XRD)和透射电镜(TEM)对不同制备方法获得的纳米铜粉在润滑油中的分散性能进行对比分析。结果表明:油幕电爆法制得的纳米铜粉分散性较好,产物纯度高,粒径分布范围10~50 nm,平均粒径为30 nm;当添加油酸的体积百分比为5%时,纳米铜粉在基础油中的吸光度最大,即其分散性最好。     

初始充电电压对电爆产物尺度分布的影响

在丝电爆过程中,初始充电电压对最终的纳米粉尺度分布有重要影响。在气体放电式丝电爆装置上进行系列试验,通过分析爆炸产物尺度分布及其形成原因,认识初始充电电压的影响。结果表明,在初始充电电压较低时,纳米粉中纳米级颗粒的平均粒径、微米级大颗粒比例随初始充电电压升高而逐渐减小,而初始充电电压过高时,纳米级颗粒平均粒径、微米级大颗粒比例反而会随初始充电电压的升高而增大。分析可知,在初始充电电压过高时,丝表面发生沿面放电现象,会阻碍能量向金属丝沉积。     

Ag包覆Ni复合纳米粉体的制备及其导电性能

用化学镀法,以葡萄糖为还原剂,制备了Ag包覆Ni复合纳米粉体,并用制备的复合纳米粉作为导电相配制了导电浆料。用XRD、TEM和电阻率测定等手段研究了粉体的相结构、形貌、粒度和导电性能。结果表明,制备的Ag包覆Ni复合纳米颗粒具有壳/核结构,核为纳米Ni,壳为Ag,复合纳米颗粒粒度分布为20~100 nm,Ag层的厚度约为4 nm。Ag包覆Ni复合纳米粉导电浆料在1.33 Pa的真空下,采用200℃/60 min的烧结工艺,可制得电阻率为(1.26~2.83)×10-4Ω·cm的导电膜,其导电性能优于纳米Ni粉、纳米Cu粉和纳米Ag-Cu合金粉导电浆料。     

丝电爆制备金属纳米颗粒的研究

开发了金属丝电爆制备纳米颗粒的设备,适用于细金属丝连续电爆制备纳米颗粒,并用高压触发管来控制爆炸位置。利用该装置将0.2mm及0.1mm丝径的镍丝、钼丝、钨丝制备成相应的纳米颗粒,结合纳米颗粒形貌、颗粒粒度分布以及爆炸过程的电流电压波形进行分析。结果表明:在爆炸位置不受控制的情况下,钼丝电爆时受大电流气体放电作用,制备的纳米颗粒粒径大且不均匀,平均粒径在40～60nm之间;而镍丝制备的纳米颗粒品质较好,平均粒径在20～30nm之间。爆炸位置受控时,可以将钨丝制成平均粒径为20.5nm的颗粒。。     

纳米铬酸锶镧制备及烧结行为

采用sol—gel法制备了铬酸锶镧纳米粉体，并用纳米粉体制成了烧结体。利用XRD、TEM及SEM方法研究了不同条件下粉末样品的物相组成、形貌及烧结体的形貌。结果表明，随着锶掺杂量的增加，La1-xSrxCrO3(x=0～0．4)粉料的粒径逐渐变小。随煅烧温度的增高，粒径逐渐增大，其最佳合成温度为800℃。粘结剂加入量及成型压力对烧结体的气孔大小和分布影响很大。     

钡铁氧体纳米颗粒的表面活性剂调控制备

以铁盐、钡盐、NaOH、Na2CO3作为反应物,采用化学共沉淀法制备了六角晶系磁铅石型的钡铁氧体BaFe12O19前驱体。在制备过程中分别添加不同种类、不同量的表面活性剂,将前驱体在850℃下进行煅烧,得到纳米球状、棒状和六角片状的BaFe12O19粉体。分别利用XRD和SEM对所制备的粉体进行了物相研究和微观形貌分析。结果表明,调节表面活性剂的种类和添加量可以有效控制BaFe12O19纳米粉体的微观形貌。制得的BaFe12O19纳米粉体在大尺寸上的粒径为100～200nm。     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

Effect of Short-Time Aging on the Pitting Corrosion Behavior of a Novel Lean Duplex Stainless Steel 2002

The effect of short-time aging in the temperature range between 400 and 1000 °C on the pitting corrosion behavior and mechanical property of a novel lean duplex stainless steel(LDSS) 2002 was investigated through the potentiostatic critical pitting temperature(CPT) tests and the Charpy impact tests. Both the pitting corrosion resistance and the toughness of aged specimens degraded due to the precipitation of detrimental secondary phases and the most significant reduction of CPT and impact energy emerged at 650 °C concurrently. The CPT of LDSS 2002 specimen aged at 650 °C decreased by 28 °C, and the impact energy dropped from 69 to 29 J/cm~2 compared with the solution-annealed sample. Transmission electron microscopy characterization showed that the main precipitates in LDSS 2002 were Cr_2N and M_(23)C_6 along the ferrite–austenite grain boundaries.     

INTRODUCTION TO PATENTS

The invention provides a method of making a mold which can reduce SOx generation rate while preventing decrease in hardening rate in the case of using sulfuric acid for a hardener composition. The method has a mixture step in which fire-resistant particles, a hardener composition and a binder composition are mixed to obtain a composition for a mold. The hardener composition contains sulfuric acid. In the mixture step, sodium carbonate is added. A molar ratio of the sulfuric acid to the sodium carbonate is 0.5 or more and 4.0 or less.     

China Foundry Week 2014

China Foundry Week, hosted by the Foundry Institution of Chinese Mechanical Engineering Society （FICMES） each year, is a large academic event in China. It is one of the ten high-impact activities sponsored by the Chinese Mechanical Engineering Society.     

17th Conference of Hydrodynamic and Electromechanical Control Engineering Call for papers

正1.Contents In order to promote the academic exchanges and technical communication of the research in the field of fluid power transmission and control,fluid control engineering specialized committee of the Chinese Society of Theoretical and Applied Mechanics will hold the 17th Conference of Hydrodynamic and Electromechanical Control Engineering on July 27-29,2014 in Tibet,Lhasa city.     

Information for Contributors

正The Transactions of Nonferrous Metals Society of China,founded in 1991 and sponsored by The Nonferrous Metals Society of China,is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology,including mineral processing,extraction metallurgy,metallic materials and heat treatments,metal working,physical metallurgy,powder metallurgy,with the emphasis     

Preface

<正>We are pleased to present this Special Issue of Transactions of Nonferrous Metals Society of China containing selected papers from the First Asian Conference on Aluminum Alloys(ACAA-2013),held in Beijing,China,13–17 October 2013.This conference has been initiated,with approval of     

Information for Contributors

The Transactions of Nonferrous Metals Society of China, founded in 1991 and sponsored by The Nonferrous Metals Society of China, is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology, including mineral processing, extraction metallurgy, metallic materials and heat treatments, metal working, physical metallurgy, powder metallurgy, with the emphasis on fundamental science. It is the unique preeminent publication in English for scientists, engineers, under/post-graduates on the field of nonferrous metals industry. This journal is covered by many famous abstract/index systems and databases such as SCI Expanded, Ei Compendex Plus, 1NSPEC, CA, METADEX, AJ and JICST.     

Formulas of Tension of Continuous Rolling Process

The development of computer controlled continuous rolling process calls for a mathematical expression that can express the inequality condition of "constant flow". Tension is the link of the continuous rolling process. From the condition of dynamic equilibrium, a differential equation of tension is given out. On the basis of the physical rules established from the industrial practice and experimental studies, the law of volume constancy, the linear relation of forward slip and tension, the state equation of continuous rolling, the formula of dynamic tension, and the formula of static tension have been obtained. These formulae reflect the functional relations between tensions, thickness, roll velocity, and time in the continuous rolling process. It is implied that the continuous rolling process is a gradually steady, controllable, and measurable dynamic system. An assumption of predicting the thickness of a steel plate using these tension formulae is also put forward.