Ball-milling MoS_2/carbon black hybrid material for catalyzing hydrogen evolution reaction in acidic medium

Replacing platinum for catalyzing hydrogen evolution reaction （HER） in acidic medium remains great chal- lenges. Herein, we prepared few-layered MoS2 by ball milling as an efficient catalyst for HER in acidic medium, The activity of as-prepared MoS2 had a strong dependence on the ball milling time, Furthermore, Ketjen Black EC 300J was added into the ball-milled MoS2 followed by a second ball milling, and the resultant MoS2/carbon black hybrid material showed a much higher HER activity than MoS2 and carbon black alone. The enhanced activity of the MoS2/carbon black hybrid material was attributed to the increased abundance of catalytic edge sites of MoS） and excellent electrical coupling to the underlving carbon network.

Novel concept of recycling sludge and dust to BOF converter through dispersed in-situ phase induced by composite ball explosive reaction

Recycling of iron and steelmaking dusts is a key issue in environmental protection efforts and to ensure efficient utilization. In this investigation, we developed a novel recovery process that uses a dispersed in-situ phase induced by an explosive reaction of composite balls of iron and steelmaking dusts. We designed and prepared composite balls for this function using a laboratory model batch-type balling disc(at 12 r/min) and optimized the feeding modes in 180-t and 260-t basic oxygen furnace(BOF) converters. The results indicate that feeding composite balls into BOF converters is an effective novel technology for recovering iron and steelmaking dusts. The period after hot metal charging and prior to the oxygen-blowing process is the most reasonable time to feed composite balls. Composite ball treatment is not appropriate for steel production with sulfur requirements lower than 80 ppm. The maximum composite ball feeding amount is 40 kg/t and the iron yield rate is better than 95%. Compared with the conventional recycling process of sludge and dust, this novel technology is more convenient and efficient, saving up to 309 RMB per ton of steel. Further investigation of this novel recycling technology is merited.

Al-Sn复合材料的制备及其水反应产氢效率

为提高Al和水的反应活性,采用高能球磨法制备了Al-Sn复合材料,通过SEM、激光粒径分析、XRD等方法表征了Al-Sn复合物的微观结构,研究了Al-Sn复合材料的水反应活性,考察了颗粒粒径、水介质、起始温度、球磨参数变化对Al-Sn复合物水反应活性的影响。实验结果表明,高能球磨法及金属Sn的加入能够大幅提高Al与水反应的活性,制备的Al-Sn复合材料与水反应的氢气产率达83.92%,快速期最大产氢速率为359mL/(min·g)。

低成本季铵盐类多孔材料的合成及氨气吸附性能

氨气是雾霾的主要污染源之一,开发高效的氨气吸附材料是一种有效的防治方法.本文选用4,4′-联吡啶、α,α′-二溴-对二甲苯和1,2,4,5-四(溴甲基)苯作为构筑单元,利用无需催化剂且操作简便的季铵化反应,原位合成了具有路易斯酸活性位点的多孔材料PAF-C1和PAF-C2.得益于骨架中路易斯酸位点的存在,这两种材料均具有良好的氨气吸附性能.其中,PAF-C2骨架中含有更多的路易斯酸位点,因此具备更优异的氨气吸附性能,在298 K和1×10^(5)Pa条件下其氨气吸附量可达5.5 mmol/g.此外,探究了材料的合成条件(温度、溶剂和保护气体)、原料用量及合成方式的影响.结果表明,以上不同反应条件制备的材料均保持优良的氨气吸附性能,从而使实现工业化合成高效氨气吸附材料成为可能.

Cu核微焊点液-固界面反应及剪切行为研究

相较于传统Sn基焊点,Cu核焊点具备更好的导热性、导电性及力学性能。为揭示尺寸效应对Cu核焊点界面反应及剪切强度的影响,制备了不同Sn镀层厚度的Cu核焊点(Cu@Ni-Sn/Cu)。观察回流不同时间后Cu核微焊点横截面微观组织,研究了Cu核微焊点在尺寸效应下的液-固界面反应。之后对Cu核微焊点进行剪切测试,结合断口形貌,分析断裂机理。界面反应结果表明:Cu@Ni-Sn/Cu焊点在250℃回流时,Sn/Ni界面生成Ni含量较高的针状(Cu,Ni)_(6)Sn_(5)IMC,Sn/Cu界面生成Ni含量较低的层状(Cu,Ni)_(6)Sn_(5)IMC。剪切测试结果表明:随着Sn镀层厚度增加,Cu@Ni-Sn/Cu焊点的剪切强度先增大后减小。基于Sn镀层厚度对界面(Cu,Ni)_(6)Sn_(5)IMC层体积的直接影响,Sn层厚度的增加提升了焊点剪切强度。然而Cu@Ni-Sn(60μm)/Cu焊点中Cu核位置的偏移,造成剪切强度略有降低。

原位自模板合成Fe/Fe_(4)C@HC复合空心球及电催化氧还原研究

化石燃料的过度依赖使人类面临着严重的能源和环境挑战,发展可再生绿色高效能源方式已成为当今社会一重大挑战。本文主要围绕Fe/Fe_(4)C@HC复合空心球催化剂的合成、表征及其电催化氧还原应用方面展开研究。采用原位自模板法合成Fe/Fe_(4)C@HC,通过XRD、SEM、TEM、EDS、XPS、BET等检测表征Fe/Fe_(4)C@HC的组成结构和微观形貌,对Fe/Fe_(4)C@HC的构效关系进行探索。电化学测试表明Fe/Fe_(4)C@HC材料具有优越的氧还原电催化性能,在氧还原催化领域具有一定的应用潜力。

Mechanochemical Reaction of Lanthanum Carbonate with Sodium Hydroxide and Preparation of Lanthanum Oxide Nanoparticle

The preparation of nano sized La 2O 3 powder by mechanochemical reaction of lanthanum carbonate with sodium hydroxide and subsequent heat treatment was studied using X ray diffraction, differential thermal and thermo gravimetric analysis and transmission electron microscopy. It was found that the mechanochemical reaction process can be divided into two steps: the first step is the multi phases mechanochemical reaction of lanthanum carbonate with NaOH to form amorphous lanthanum basic carbonate and lanthanum hydroxide, and the second step is the crystallization of basic lanthanum carbonate with the formula of La 2(OH) 2(CO 3) 2·H 2O under a quasi hydrothermal synthesis condition caused by the mechanical ball milling. The synthesized La 2O 3 powder appears clearly separated spherical like monodisperse nano size particles in which particle size ranges from 30 to 50 nm.

Microstructure of TiAl alloy prepared by intense plastic deformation and subsequent reaction sintering

TiAl alloy was prepared by intense plastic deformation and subsequent reaction sintering. The effect of plastic deformation on the microstructure of sintered TiAl alloy was investigated using energy dispersive X ray spectroscopy (EDS), optical microscopy and transmission electron microscopy (TEM). The results show that the intense plastic deformation of reacting Ti and Al phases caused by high energy ball milling refines the as sintered microstructure. The longer the milling time, the finer the grain size of γ and lamellar ( α 2 + γ ) phases. The finer grain size improves the properties of the TiAl alloy. It is also found that the volume fraction of lamellar ( α 2 + γ ) phases increases first, then decreases with increasing milling time. Based on the experimental results theoretical discussion was presented.

Fabrication of an r-Al_2Ti intermetallic matrix composite reinforced with α-Al_2O_3 ceramic by discontinuous mechanical milling for thermite reaction

In this study, a powder mixture with an Al/TiO2 molar ratio of 10/3 was used to form an r-Al2Ti intermetallic matrix composite （IMC） reinforced with α-Al2O3 ceramic by a novel milling technique, called discontinuous mechanical milling （DMM） instead of milling and ignition of the produced thermite. The results of energy dispersive X-ray spectroscopy （EDX） and X-ray diffraction （XRD） of samples with varying milling time indicate that this fabrication process requires considerable mechanical energy. It is shown that Al2Ti-α-Al2O3 IMC with small grain size was produced by DMM after 15 h of ball milling. Peaks for γ-TLA1 as well as Al2Ti and Al2O3 are observed in XRD patterns after DMM followed by heat treatment. The microhardness of the DMM-treated composite produced after heat treatment was higher than Hv 700.

Study on laser and hot air reflow soldering of PBGA solder ball

Laser and hot air reflow soldering of PBGA solder ball was investigated. Experimental results showed that surface quality and shear strength of solder bump reflowed by laser was superior than the solder bump by hot air, and the microstructure within the solder bump reflowed by laser was much finer. Analysis on interfacial reaction showed that eutectic solder reacted with Au/Ni/Cu pad shortly after the solder was melted. Interface of solder bump reflowed by laser consists of a continuous AuSn 4 layer and remnant Au element. Needle like AuSn 4 grew sidewise from interface, and then spread out to the entire interface region. A thin layer of Ni 3Sn 4 intermetallic compound was found at the interface of solder bump reflowed by hot air, and AuSn 4 particles distributed within the whole solder bump randomly. The combination effect of the continuous AuSn 4 layer and finer eutectic microstructure contributes to the higher shear strength of solder bump reflowed by laser.

合成酯润滑油磨损腐蚀的评价方法及机理研究

润滑油的磨损腐蚀是造成传动系统腐蚀的重要因素。某齿轮传动系统使用合成酯润滑油后轮齿摩擦表面出现了磨损腐蚀,严重地影响到齿轮传动系统的可靠运行。采用两款合成酯润滑油对比的方法,在125℃,392N,1200r/min及60min等试验参数下,建立了用四球摩擦磨损试验机来评价合成酯润滑油磨损腐蚀的试验方法。该方法可以有效评价和区分合成酯润滑油的磨损腐蚀。能谱分析表明,在机械因素和化学因素的交互作用下,合成酯中的磷酸三甲酚酯与金属表面发生摩擦化学反应,在起抗磨作用的同时,生成的磷酸在摩擦表面局部聚积造成了磨损腐蚀。

化学龙珠——海藻酸钠凝胶球的制备

交联反应是高分子化学中的一类反应,常用于高聚物合成和改性,如塑料、树脂和橡胶。文中科普实验设计出一种极具创意、简单易行、绿色的改性海藻酸钠凝胶球的制备方法,并经红外光谱分析证实了交联反应的发生。在此基础上,对海藻酸钠凝胶球进行了创造性的设计,开发出改性海藻酸钠pH响应微球、漂流瓶等,在趣味性的体验中搭建了社会化的科普平台,向大众普及功能高分子材料及其交联反应的知识,形成科学认识事物的新思路。

Ba_((1-x))Nd_(x)Ti_((1-y))Mg_(y)O_(3)陶瓷及其介电性能研究

实验采用高能球磨-固相合成法,将Nd^(3+)/Mg^(2+)掺杂到反应物体系中,制备了具有钙钛矿结构的Ba_((1-x))Nd_(x)Ti_((1-y))Mg_(y)O_(3)(取x=0.005,y分别取0.005、0.01、0.015)陶瓷粉体。XRD晶相分析表明,所制备的粉体主晶相为四方相钙钛矿型晶体结构;SEM形貌分析表明,Nd^(3+)/Mg^(2+)共掺具有显著细化晶粒的作用,能够提高其耐压性能,并有效改善陶瓷的介电性能。电学性能分析结果表明,随着Mg^(2+)引入比例的提高,其介电常数(ε_(r))呈现先增大后减小的趋势,介电损耗(tanδ)呈现先减小后逐渐增大的趋势,绝缘电阻(R)和直流击穿强度呈一直增大趋势。当Nd^(3+)/Mg^(2+)摩尔比为1:2时,综合介电性能最佳。

基于谱分析的全焊接球阀抗震特性分析

为研究全焊接球阀的抗震特性,利用振型分解反应谱法和从PEER地震数据库获取的实际地震数据,计算得到球阀在横向、纵向、竖向及组合地震载荷作用下球阀的地震响应,发现球阀在横向、纵向及组合地震载荷作用下,球阀阀体与管道连接处为危险位置;在竖向地震载荷作用下,最大应力出现在球体与支撑板的连接处。按照JB 4732标准对危险截面进行评价,结果表明全焊接球阀在地震载荷下安全;根据分析结果提出建议,在设计时可采用极限设计法,并且在安装使用过程中应重点关注危险截面处的横向和竖向位移。

机械合金化的研究及进展

简述了机械合金化的应用，总结了机械合金化的理论研究及其过程中的影响因素，介绍了近期主要的有关反应球磨的工作，着重叙述了反应球磨中的SHS现象。

反应球磨技术制备纳米材料

本文综述了反应球磨技术制备纳米材料的研究及应用 ,重点对反应球磨反应机理作了探讨。研究表明球磨过程中引入的高密度缺陷和纳米界面大大促进了自蔓延高温合成 (SHS)反应的进行 。

反应球磨中Mg的直接氢化

采用反应球磨法使 Ｍｇ在 ＺｒＦｅ１．４Ｃｒ０．６的催化作用下直接氢化生成纳米结构的 ＭｇＨ２和ｒ－ＭｇＨ２利用 Ｘ射线衍射及热重分析对氢化相的生成进行分析和表征．在反应球磨过程中存在动态的氢化平衡．

在氮气中球磨Ti粉制备纳米TiN_x

采用Spex型振动式高能球磨机在氮气中球磨Ti粉,采用X射线衍射和扫描电镜分析产物的相结构和形 貌。结果表明,Ti粉在氮气中球磨9h,可完全转变为,fcc结构TiNx纳米粉。

机械力化学技术研究进展

金属和无机非金属粉末在高能球磨过程中受到强烈的机械力作用 ,组织不断细加、内部缺陷不断增加 ,导致材料体系自由能大幅度提高 ,在球与粉末颗粒碰撞的瞬间可以诱发固 固、固 液和固 气态化学反应。利用这种工艺被称之为机械力化学 ,可广泛用于制备纳米晶材料、复合纳米材料、纳米粒子、弥散强化材料、高分子聚合物以及进行矿物、废物处理和金属精炼。深入讨论了机械力化学过程的原理、特点及其应用。

Al/CuO的高能球磨固态反应

系统研究了Ａｌ／ＣｕＯ的高能球磨固态反应。对Ａｌ含量在２０％～８５％范围内的Ａｌ／ＣｕＯ进行高能球磨，采用Ｘ射线衍射进行物相分析，并对Ａｌ含量分别为２０％和７５％的试验分析了物相随研磨时间的变化，做了差示扫描量热（ＤＳＣ）分析，对比研究了固态还原反应与固态复合反应过程的异同。结果表明，Ａｌ含量不超过２０％时仅发生单纯的还原反应；当Ａｌ含量从２０％分别增加到３５％，５７％，７０％和８５％时，反应为还原与合成共存的复合反应，产物依次为Ｃｕ９Ａｌ４，ＣｕＡｌ２及Ａｌ（Ｃｕ）固溶体和Ａｌ２Ｏ３的复合颗粒。