机械化学合成Ni2Al3/Al2O3去合金化制备Raney-Ni/Al2O3复合粉体

以NiO粉和Al粉为原料,采用机械球磨诱发化学反应制备了Ni_2Al_3/Al_2O_3复合粉体。利用X射线衍射仪(XRD)和附带能量色散谱仪(EDS)的扫描电子显微镜(SEM)对复合粉体球磨过程中的固态反应过程、表面形貌进行表征。将Ni_2Al_3/Al_2O_3复合粉体用浓度为20%的NaOH溶液腐蚀2h,可得到纳米晶结构的Ni/Al_2O_3复合粉体。利用XRD和TEM对其物相和结构进行了表征。结果表明,球磨1h后混合粉末仍为NiO粉和Al粉,球磨3h后NiO粉和Al粉在机械力的作用下反应形成Ni_2Al_3和Al_2O_3粉体,机械力诱发的NiO和Al之间的反应属于突发型反应,继续球磨10h后形成Ni_2Al_3/Al_2O_3复合粉体。Ni_2Al_3/Al_2O_3复合粉体在70℃、质量比为20%NaOH溶液中刻蚀2h,可获得Ni/Al_2O_3复合粉体。     

高能球磨法制备超滤分离膜用钼铜复合粉末

研究高能球磨法制备纳米钼铜复合粉末的主要影响因素,通过扫描电镜和透射电镜分析粉末的形貌及颗粒尺寸.研究结果表明,复合粉的粒度随着球磨时间的延长而减小,但随着球磨时间增加,团聚加剧;通过重力沉降法可以去除浆体中的团聚体,从而获得颗粒分布适合的粉体,10h球磨粉沉降后粉体颗粒尺寸约为50～60nm,20h球磨粉沉降后粉体颗粒尺寸约为20～30nm.     

机械合金化Al-ZnO粉末的固相反应

采用X射线衍射仪、电子扫描和DTA差热分析等手段,研究了在Ar气氛保护下Al-ZnO粉高能球磨过程中发生的机械合金化反应,分析了不同球磨时间对粉体成分、形貌、热稳定性的影响及对生成Al2O3粒子的反应进程和颗粒大小的影响.结果表明,高能球磨是一种有效实现Al-ZnO固相置换反应的方法,经过30 h球磨后,Al-ZnO完全发生机械合金化反应,60h后可获得Zn包覆的纳米级的Al2O3颗粒,置换生成Zn的熔点降低到398℃.     

高能球磨Mg/B复合粉末的特性

对化学计量比的Mg/B原始粉体进行高能球磨,通过扫描电镜SEM和能谱分析EDX对球磨前后的粉末进行观察,对球磨过程中复合粉末的组织形貌和成分分布的变化进行了研究.结果表明:随着球磨时间的延长,Mg粉明显细化,B粉在Mg粉中的均匀弥散分布程度很好.     

高能球磨中促进粉体细化的主要因素研究

高能球磨技术作为一种制备包括纳米粉体在内的多种亚稳相材料的有效方法,已获得广泛应用.通常可以添加过程处理剂或在低温下球磨来抑制球磨过程中的冷焊,促使粉末细化.利用外加物理能场辅助高能球磨,使物理能与机械能协同作用到粉末,也是提高高能球磨效率的一种有效途径.根据不同条件下Fe粉的球磨细化结果,分析了高能球磨中过程处理剂、低温和外加能场辅助等主要促进粉体细化的因素及其作用.研究表明,采用等离子体辅助球磨仅仅10h,铁粉颗粒就被细化到了100nm.这种高的细化效率是因为等离子体辅助球磨中,等离子体对粉体产生的热爆效应和热应力的协同作用使粉体更易细化.     

转炉烟尘制备氮化铁磁粉的研究

转炉烟尘通过湿法(硫酸和氨水)冶金提纯净化、高能球磨处理后,在NH3/H2气氛下进行还原氮化,以穆斯堡尔谱学、X光衍射等方法对处理试样进行物相分析.结果表明,Ar气氛下球磨2h后,经550℃/2h还原、550℃/3h氮化(NH3/H2=3/4,降温时NH3/H2=1/6)处理,γ'-Fe4N 的生成量≥91%.     

高能机械化学法制备微纳米Mo—Si粉体

以Mo粉和Si粉为原料,通过自行设计的高能机械化学球磨机在室温下制备出了微纳米Mo-Si粉体,利用X射线衍射（XRD）和扫描电子显微镜（SEM）进行物相分析和粒度分析,结果表明,在不同的反应阶段会生成MoSi2和Mo5Si3,并且生成物之间相互有一定的转化,反应生成率接近100％,制备出的微纳米Mo—Si粒度在100nm左右,在Mo和Si的高能机械化学反应中,适当地提高球料比和转速可以加快反应的进程。     

高活性B_4C-SiC超细复合粉体的制备及烧结

以B4C、SiC粗粉为原料,采用机械合金化制备高活性的B4C-SiC超细复合粉体。通过XRD、SEM、LPSA和IR等测试技术研究球料比、过程控制剂及球磨时间对复合粉体性能的影响,确定机械合金化制备B4C-SiC超细复合粉体的最佳工艺条件,研究机械合金化过程中粉体有序-无序转变过程。随后,采用热压烧结工艺验证复合粉体的烧结活性。结果表明:球磨机转速是250 r/min的条件下,球料比为30:1,过程控制剂为2wt%,球磨时间为120 h时,可获得晶格无序的B4C-50wt%SiC超细复合粉体;该复合粉体在1900℃,30 MPa热压条件下烧结1 h,其体积密度为2.62 g/cm3,达到理论密度的93%,比普通混合粉体在相同热压条件下获得样品的致密度提高了8.1%;机械合金化工艺制备的B4C-SiC超细复合粉体具有极高的烧结活性。     

TiCN超细粉末的制备工艺研究

采用湿式高能球磨法制备超细TiCN粉体,考察不同球磨时间下粉体粒度的分布情况,分析球料质量比和球磨时间对TiCN粉体粒度的影响,并利用扫描电镜观察制备粉体的形貌。结果表明:随着球料质量比和球磨时间的增加,TiCN粉体平均粒径均出现先减小后增大的趋势,当球料质量比为8∶1时,球磨50h可获得平均粒径为0.84μm的类球形TiCN粉体。     

高能球磨制备TiB2/TiC纳米复合粉体

研究了通过高能球磨制备TiB2/TiC纳米复合粉体的反应过程和机理,对粉体的显微结构进行了表征。实验结果表明,采用金属Ti和B4C为原料,在球磨过程中,TiC先于TiB2形成。球磨5h后Ti与B4C反应生成TiB2和TiC,在随后的长时间高能球磨过程中TiB2和TiC两相保持稳定。球磨30h后,直径约8nm的TiC纳米粒子分布在100-200nm的TiB2粒子中,形成均匀分布的纳米TiB2/TiC复合粉体。     

Mechanochemistry of sulphides

At present mechanochemistry of sulphides appears to be a science with sound theoretical foundation exhibiting a wide range of opportunities in different area of science and technology. For traditional applicationsmechanochemistry is of exceptional importance in mineral processing and extractive metallurgy. Mineral disordering by high energy milling has a positive influence on the reaction kinetics and further phenomena, such as changing the reaction mechanism to reduce environmental impacts. Metal sulphides can be utilized nowadays, in advanced applications such as precursors for synthesis of high temperature superconductors, luminescent and solar energy materials, high-energy density batteries and further materials for opto-electronic and magnetic applications. Mechanochemistry in this case serves as a tool which can effectively control and regulate the solid state reactions for advanced materials preparation. It is aim of this review paper to illustrate the progress in mechanochemistry of sulphides achieved in recent years in Slovakia.     

机械力化学法合成无机材料的研究进展

粉体球磨过程中,机械力化学使颗粒和晶粒细化产生裂纹,比表面积增大,晶格缺陷增多,晶格发生畸变和结晶程度降低,甚至诱发低温化学反应,可以制备出高活性陶瓷粉体和性能优异的材料.本文介绍了机械力化学在无机材料研究中的最新进展,影响因素及应用.同时,对其未来发展进行了展望.     

Producing ternary intermetallic compounds powders by solid–liquid reaction ball milling

A novel mechanochemistry approach, defined as solid–liquid reaction ball milling, was applied to obtain single-phase Al–Cu–X (X = Fe, Co, and Ni) ternary intermetallic compound powders by reactions between milling medium (ball and cylinder) and liquid-state metals in certain temperature range, where the milling mediums made of metals with high-melting point and took part in the reaction as the solid-state reactants. Compared with the conventional mechanical milling technique, nanometer-sized intermetallic compound powders and some single-phase ternary intermetallic phases could be obtained at lower temperatures by the solid-state reaction ball milling. Furthermore, the reaction mechanisms of this mechanochemical approach have been discussed in details.     

固液反应球磨技术的研究进展

固液反应球磨是在机械力化学和机械合金化基础上发展起来的一种新型的材料制备技术,其在金属间化合物的制备方面显示出了独特的优越性。在综述了固液反应球磨技术的特点和机理基础上,重点阐述了固液反应球磨技术的过程模型及其在金属间化合物制备方面的应用,并对其今后的研究方向进行了讨论。     

Nb和N2在球磨过程中的固—气反应

利用改装后可充一定压力气体的球磨罐,装入一定量的高纯金属,经抽真空后充入一定压力的氮气,在室温下进行球磨产生固－气反应制备出金属氮化物的超细微粒,以金属铌为例,用XRD和TEM分别对生成物的晶粒尺度和相结合进行了分析测量,从热力学讨论了金属氮化的形成机制,在固－气反应中氮气分子在金属清洁表面的化学吸附起着重要作用,球磨过程中产生的大量缺陷对金属－氮气的反应有重要影响。     

氮化钼膜电极制备工艺及其电化学行为的研究

研究了氮化钼膜电极的浸渍－煅烧法制备工艺条件及其电化学行为．试验结果表明,浸渍－煅烧法制备高活性氮化钼电极适宜的浸渍干燥温度为５１３～４７３Ｋ,煅烧升温速率为１Ｋ·ｍｉｎ^－１,煅烧温度为９９０Ｋ,煅烧时间为２ｈ;冷却方式为在氨气保护下随炉降温;浸渍－煅烧法制备的氮化钼电极成膜均匀,与基体附着性强;在－０．２２～０．３６Ｖ（ｖｓ ＳＣＥ）电位范围内,循环伏安图基本上呈现矩形,当扫描速度ｓ≤１００ｍＶ·ｓ^－１时,电流密度与电势扫描速度成正比,电极电容特征显著,动力学可逆性好,稳定性与重现性好．     

The feasibility of synthesis tungsten nitride in magnesium‐tungsten oxide‐melamine ternary system via mechanochemical method

Different routes have been investigated to synthesize tungsten (W) – tungsten nitride (W₂N) nanocomposite powder by mechanochemical method in magnesium–tungsten oxide–melamine ternary system. In stoichiometric mixture, reduction of tungsten oxide by magnesium took place after 30 minutes of milling in mechanically induced self‐sustaining reaction (MSR). A large amount of heat generated from magnesiothermic reaction, makes the used melamine unstable which causes the formation of undesirable tungsten carbide phase. By separating magnesiothermic reduction from nitride formation reaction, no thermal degradation of melamine occurred; however, milling alone has not brought much change in the used melamine to form tungsten nitride. Dispersion of reaction heat by adding magnesium in three‐stages (during 3 hours of milling) has been capable of preparing maximum value of tungsten nitride phase. According to scanning and transmission electron microscope images, the range of particle size was within 100 nanometer.     

Joining of silicon nitride to SUS304 stainless steel using a sputtering method

Silicon nitride with thin sputter-deposited titanium and nickel films was joined to SUS304 stainless steel (18% Cr-8% Ni) using metallic buffers in a series of silicon nitride/nickel/ molybdenum/nickel/SUS304, and the joining strength and microstructures were investigated. Four-point bending tests showed fracture strength of the joints up to 169 MPa. Cracks were formed at the interface between the silicon nitride and its adjacent nickel buffer, and frequently extended into the silicon nitride. Microstructural analyses revealed that the silicon nitride reacted with the sputter-deposited titanium producing titanium nitride and isolated silicon atoms, and that silicon and titanium diffused into the nickel buffer. Calculations using a finite-element method indicated a marked reduction in thermal stress induced in the joined silicon nitride with increasing thickness of the molybdenum buffer. The strong interfacial bond inducing the fracture of the joined silicon nitride was interpreted in terms of a good interfacial reaction, the interdiffusions and the reduction of thermal stress being due to the insertion of the molybdenum buffer.     

反应球磨钛与尿素制备氮化钛的反应机理研究

将Ti粉与尿素在室温下进行反应球磨制备了TiN粉末,对球磨不同时间后的粉末进行XRD分析,采用TG-FTIR技术分析了尿素的分解温度与产物,利用TEM及EELS观察和分析了球磨70h粉末的微观形貌、结构及成分. 结果发现,球磨70h合成了纳米TiN粉末,晶粒度为6~7nm,Ti/N原子比约为1.0∶0.6. 经800℃,5h真空退火处理后粉末的XRD谱图表明粉末组成为单相TiN. 在反应球磨过程中,Ti与尿素的分解产物NH₃与HNCO发生反应形成TiN,随球磨时间延长,Ti的缺陷能增大、活性增加,N在Ti中的扩散激活能减小,在球磨作用下N的扩散距离变短,TiN的含量逐渐增加形成晶核并逐渐长大形成纳米晶.     

Factors influencing the kinetics of electrochemical reactions in milling

Input of mechanical energy at a high rate can drive a system and induce phase transformations and chemical reactions away from equilibrium. The evolution of such a change depends on both thermodynamic as well as kinetic factors. Besides the microstructural changes like attainment of nanostructure, which alters the overall free energy, the high rate of mechanical energy input also changes the kinetics by influencing the mass transport and related processes. In order to understand these factors, we have recently started a programme of looking at the influence of mechanical energy on driving simple chemical reactions in solid state. In this presentation we shall present and discuss the results of two kinds of situation that we have studied. The first one is simple electrochemical replacement reactions between metals and metal sulphates in solid state. We show that the mechanical milling alters the kinetics of these reactions, which can be rationalized by considering the phenomena taking place at the microscopic level. For example we will show that the crystal structure of the sulphate and the nature of the reaction product at the interface influence the mechanochemistry significantly. It is even possible in some special cases to alter the direction of the chemical reaction. In the second set of results we shall present the effect of mechanical milling on the site occupancy in ferrites, which can lead to a significant change in magnetic behaviour.