对再生镁碳砖制备过程中碳化铝的研究

针对在镁碳砖或再生镁碳砖制备过程中被公认为有害物质的碳化铝进行了研究。在所研究的热处理温度范围内,确定了碳化铝的形成机理。在实验中研究了热处理温度和石墨加入量对碳化铝(Al4C3)形成的影响。     

基于电化学性能的La-Mg-Ni系储氢合金的成分优化

以La-Mg-Ni系A2B7型储氢合金为研究对象,系统分析了合金A、B侧元素含量对其电化学性能的影响。对La1-m-n-y Pr m Nd n Mg y(Ni1-z Co z)x合金的容量和衰减速率进行了讨论。结果表明,合金容量随B/A值的增大先增大后减小,当x=3.5时,合金的容量最大,衰减速率最小;最佳的合金配比为La0.5Pr0.2Nd0.1Mg0.2(Ni0.8Co0.2)3.5。XRD分析表明,La1-m-n-y Pr m Nd n Mg y(Ni1-z Co z)x的合金主相结构均为Ce2Ni7型La2Ni7相。     

新型磷酸盐结合耐火散状料的研制与应用

以优质高铝矾土熟料(体积密度3.18 g·cm-3)或致密刚玉及烧结α-Al2O3微粉为主要原料,采用固体磷酸二氢铝作为结合剂,研究了分散剂SiO2超细粉、促凝剂矾土水泥、抑制剂NH-66和骨料粒度组成对新型磷酸盐耐火散状料性能的影响.结果表明,SiO2超细粉、矾土水泥、NH-66外加量分别为3.5%、2.5%和0.12%,喷补料骨料临界粒度为4 mm,浇注料粒度组成为10～5访m及≤5 mm的两级连续通料时,所研制散状料具有施工简便,强度高,耐磨性优,可以快速进行热处理的特点.通过试验生产验证,研制的材料致密性、耐磨损性和抗冲刷性能比现有的浇注料要好,能满足相关的使用条件和要求.     

6061铝合金焊接变形的数值分析

本课题是上海汽车工业基金汽车轻量化研究工作的一部分。汽车轻量化对于节省能源、保护环境、提高安全都有着重要的现实意义,而铝合金材料的应用则是解决该问题的有效途径之一。目前,国内在这一方面尚与先进国家存在较大差距,主要是由于铝合金结构在焊接工艺上存在较大问题。国内外相关文献主要集中在焊后组织及性能的模拟,本课题旨在对铝合金结构的焊接变形进行数值分析,为制定和优化焊接工艺提供必要的参考。     

基于CORBA的铝型材产品开发分布式决策支持系统的研究

介绍了铝型材产品开发分布式决策支持系统原型框架、主要功能、运行过程及实现方法 ,该系统基于COR BA规范和MAS技术构建 ,可以充分利用多来源的领域知识提高铝型材产品开发工程人员决策有效性     

大厚度铝合金变极性等离子弧穿孔立焊技术

研制以16位单片机为控制核心的双逆变型铝合金变极性等离子弧穿孔立焊专用设备,测试并分析变极性等离子电弧力学特性,对变极性等离子弧稳定性、电弧力和电弧能量的传递特征进行了深入的探讨。研究发现铝合金变极性等离子穿孔焊接中正极性电弧对力更具影响,而反极性电弧对热更具影响,实时保持穿孔熔池上热和力的平衡是厚板变极性等离子弧稳定穿孔焊接关键所在。用自行研制的设备成功实现了15 mm LD10铝合金变极性等离子弧穿孔立焊工艺,研究结果对于将变极性等离子弧焊接工艺应用到我国航空航天等领域具有重要的现实意义。     

Mechanical and tribological properties of a novel aluminum bronze material for drawing dies

A new aluminum bronze material with aluminum content over the solubility limit and several trace elements, Cu-14Al-X alloy (X is trace elements), has been developed for drawing dies. The mechanical properties such as hardness, tensile strength and impact toughness were evaluated experimentally. The friction and wear behavior of the material was investigated under boundary lubrication conditions. The experimental results demonstrated that the developed alloy possessed higher tensile strength and hardness, lower friction coefficient and wear rate, compared to currently used aluminum bronzes, therefore it is expected to replace conventional iron-based materials that are commonly used for drawing dies. With the excellent anti-friction property and high carrying capacity, the new material, Cu-14Al-X alloy, will be able to provide precision drawing dies.     

Development of Ti–Nb and Ti–Nb–Fe beta alloys from TiH2 powders

Ti–Nb β alloys are a promising alternative as an implant material due to their good properties and low Young’s modulus, compared to other Ti-alloys currently employed as biomaterials. In this study, three materials of the Ti–Nb and Ti–Nb–Fe systems were produced by powder metallurgy techniques starting from TiH₂ (TH) powder. Several sintering cycles were employed to evaluate the H₂ elimination and the effect of sintering temperature on densification and fraction of β-Ti phase. Also, the influence of alloying element size using two kinds of Fe powder was evaluated. The highest loss of H₂ was achieved by decreasing heating rate at the temperature range of hydride decomposition. SEM images and XRD results show mainly a β-Ti phase for TH–40Nb and TH–5Fe–25Nb samples. The TH–12Nb sample shows (α?+?β) microstructure. Fe addition with smaller particle size seems to improve the diffusion of Nb into Ti which promotes a higher β-phase fraction and sample homogeneity.     

电感耦合等离子体原子发射光谱法测定钛及钛合金中铬和铜

铬、铜含量影响钛及钛合金组织结构和性能,须对其准确测定。采用硫酸-硝酸溶样体系溶解样品,选择Cr 267.716nm、Cu 327.393nm为分析线并采用两点校正法扣除背景,使用钛基体匹配的方法绘制校准曲线,使用电感耦合等离子体原子发射光谱法(ICP-AES)测定钛及钛合金中铬和铜。方法中各元素校准曲线线性良好,相关系数均大于0.999;检出限为0.04~6.0μg/g。按照实验方法测定3个钛及钛合金样品中铬和铜,结果的相对标准偏差(RSD,n=10)小于5%。按照实验方法测定5个钛合金标准物质中铬和铜,测定结果与认定值相吻合,分析误差在实验室允许的误差范围内。     

Fast reactions with nano- and micrometer aluminum: A study on oxidation versus fluorination

The use of fluorine as an oxidizing agent in aluminum (Al)-based thermite reactions yields higher peak pressures and an increase in gas production compared with oxygen-containing oxidizers, such as molybdenum trioxide (MoO₃). Thus fluorination reactions have the potential to excel in situations that require high pressures and flame speeds. This study compares the combustion behaviors of Al/Teflon, Al/MoO₃/Teflon, and Al/MoO₃ in an effort to determine the effects that the replacement of oxygen with fluorine has on the reaction dynamics in both open and confined burning configurations. Data were collected from pressure sensors and high-speed imaging. The mass percent of Al was varied from 10 to 90% to study the effects of composition. The composites were then further tested at the optimum stoichiometry using either 50 nm or 1-3 μm Al to examine the effect of Al particle size. The addition of Teflon in an open configuration hinders the reaction due to a loss of liberated gas. Confining the reaction enables the trapped gases to enhance convection, yielding increased flame speeds. For confined conditions, the reactions containing Teflon exhibit higher peak pressures but lower flame speeds than the reactions with MoO₃. These results imply that a direct relationship between generated gas pressures and flame speeds does not generally exist when comparing different oxidizers. The theoretically predicted relationship for the relative flame speed versus relative particle size based on the melt-dispersion mechanism agrees with experimental data for all Al particle sizes and for the fluorination reaction. Particle synthesis parameters are suggested that could be controlled to enable micrometer-scale Al particles to achieve the performance of nanoscale Al particles. This is of significant practical importance, because nanoparticles are 30 to 50 times more expensive than the micrometer particles.