机械合金化19Cr-14Ni不锈钢粉末激光熔覆层的组织和性能

激光熔覆所用粉末材料的制备方法主要是雾化法。为探索激光熔覆专用材料的制备新方法,将以单元素粉末的形式,按照19Cr-14Ni不锈钢的成分来配制混合粉,并将该混合粉机械合金化45h,在45#钢板上分别将采用上述两种不锈钢粉末进行激光熔覆。采用X射线衍射(XRD)、扫描电镜(SEM)/能谱仪(EDS)、腐蚀电化学等方法研究熔覆层的相组成、微结构和耐蚀性。结果表明,与雾化粉体激光熔覆层相比,机械合金化粉体激光熔覆层的枝晶得到细化,其组织呈连续网状分布,Cr元素的枝晶间偏析得以改善;与雾化粉体相比,机械合金化能提高粉体熔覆层的耐蚀性能,但其硬度略有降低。     

Interfacial reactions between a Pb-Free solder and die backside metallizations

The interfacial reactions between Sn-3.0 Ag-0.7 Cu solder and backside metallizations on two semiconductor devices, field-effect transistors (FET) and diode, are studied. The metallizations on both devices were vacuum evaporated Ti/Ni/Ag. The intermetallic compounds (IMC) formed near the diode/solder and FET/solder joints during reflow, and the interdiffusion processes during solid state aging are characterized by the quantitative energy dispersive x-ray analysis and the x-ray mapping technique in a scanning electron microscope. Two different intermetallic compounds are found near the diode/solder interface. Both are in the form of particles, not a continuous layer, and are referred to as IMC-I and IMC-II. IMC-I corresponds to Ni₃Sn₄, with Cu atoms residing on the Ni sublattice. It is uncertain whether IMC-II is Cu₆Sn₅ or a Cu-Ni-Sn ternary phase. Near the as-reflowed FET/solder interface, both isolated scallops and a skeleton-like layer of Ni₃Sn₄ are observed. The primary microstructural dynamics during solid-state aging are the coarsening of IMCs and the reactions involving the Ni-and Ti-layer with Sn and Au. While the reaction with the Ni-layer yields only Ni₃Sn₄ intermetallic, the reaction involving the Ti-layer suggests the formation of Ti-Sn and Au-Sn-Ti intermetallics. The latter is due to the diffusion of Au from the substrate side to the die side. It is postulated that the kinetics of the Au-Sn-Ti layer is primarily governed by the diffusion of Au through the Ni₃Sn₄ layer by a grain boundary mechanism.     

低温烧结改性PbTiO_3压电陶瓷材料的研究

研制了一种添加 Bi(Cd1 / 2 Ti1 / 2 ) O3、Mn O2 、Si O2 的新型低温烧结改性 Pb Ti O3压电陶瓷材料。实验发现 ,低熔物 Si O2 是影响烧结的主要因素 ,除能明显降低该材料烧结温度外 ,还能起掺杂改性作用。该材料具有低烧结温度、高压电活性、大压电各向异性、较高机械品质因数及低介电常数等优点。 96 0°C烧成时主要性能参数为 :厚度机电耦合系数 kt=0 .49;径向机电耦合系数 kp=0 .0 2 7;压电各向异性比 kt/ kp=18;压电应变常数 d33=6 5 p C.N- 1 ;机械品质因素 Qm=5 14;密度 ρv=7.4g.cm- 3;居里温度 TC=312°C;介电常数 εT33/ ε0 =177;介质损耗 tanδ=0 .6 3%。该材料在叠层压电滤波器和叠层压电降压变压器方面显示出很好的应用前景。     

Bi_2O_3对自燃烧法合成NiZnCu铁氧体的显微结构与性能的影响

以金属硝酸盐和柠檬酸为原料 ,应用溶胶 -凝胶法与自燃烧结合的方法制备了 Ni Zn Cu铁氧体微细粉。文章主要讨论了溶胶 -凝胶与自燃烧法结合制备 Ni Zn Cu铁氧体粉末的新方法 ,对 Bi2 O3掺杂的低温烧结 Ni Zn Cu铁氧体从烧结性质、结构与相组成、显微形貌、磁性质方面进行了研究 ,在此基础上分析了 Bi对材料形成过程和磁化机制的影响 ,并解释了掺杂量对材料磁性能的综合作用     

MH/Ni电池用泡沫式镍正极的进展

本文综述了近几年来有关Ni(OH)_2的制备、物理和化学性质以及对Ni(OH)_2电极活性有重要影响的添加剂方面的研究与应用的新进展,介绍了泡沫式镍电极的制备方法,探讨了获得高性能泡沫镍电极的工艺途径,指出当前我国泡沫镍电极产业化过程中存在的一些问题,并就泡沫镍及其电极的未来发展提出了一些看法。     

9Ni钢中马氏体孪晶界面结构研究

本文和电子显微研究了９Ｎｉ钢中马氏体孪晶界面精细结构，结果表明，马氏体孪晶不是平直的孪生面（１１２），而是由一系列以享生面（１１２）为平台的小平面组成的台阶状或凹凸不平的界面。小平面大多沿「１１０」方向形成，沿「１１１」方向较少形成。     

光化学汽相淀积技术在薄膜备制中的应用

介绍了光化学汽相淀积法的原理以及ＰＶＤ－１０００设备淀积薄膜的规律，特点等，并且给出了所淀积的ＳｉＯ２膜，Ｓｉ３Ｎ４膜和ＺｎＳ膜的基本特性。     

溶胶—凝胶工艺制备梯度折射率薄膜的研究

采用溶胶－凝胶工艺制备梯度折射率薄膜，薄膜中的折射率变化是由折射率调制元素在湿凝胶中的化学反应和扩散产生。本文详述了材料的制备过程，并对材料的结构和光学性能进行了研究。     

不同镍含量钨基碳化态催化剂对十氢萘加氢开环的影响

采用共浸渍法制备不同镍含量的Ni-W/ USY-Al2O3碳化态催化剂。通过N2吸附-脱附、元素分析、CO滴定、X射线衍射（XRD）、程序升温还原等技术对催化剂进行表征。以十氢萘为模型化合物考察了不同Ni含量钨基碳化态催化剂对十氢萘加氢开环反应性能的影响。结果表明，适当的镍钨原子比能够提高催化剂的金属活性位，进而提高催化剂的加氢开环性能。     

Metal effects in the Fischer-Tropsch synthesis: Bond-order-conservation-morse-potential approach

We have applied the BOC-MP method to theoretically analyze the metal effects in the Fischer-Tropsch (FT) synthesis by calculating the energetics of conceivable elementary steps (the relevant heats of chemisorption and the reaction activation barriers) during CO hydrogenation over the periodic series Fe(110), Ni(111), Pt(111), Cu(111). The basic steps such as dissociation of CO, hydrogenation of carbidic carbon, C-C chain growth by insertion of CH₂ versus CO into the metal-alkyl bonds, and chain termination leading to hydrocarbons (alkanes versus -olefins) or oxygenates are discussed in detail. It is shown that the periodic trends in the ability of metal surfaces to dissociate chemical bonds and those to recombine the bonds are always opposite. In particular, we argue that metallic Fe is necessary to produce the abundance of carbidic carbon from CO but the synthesis of hydrocarbons and oxygenates can effectively proceed only on carbided Fe surfaces which resemble the less active metals such as Pt. More specifically, we project that the C-C chain growth should occur predominantly via CH₂ insertion into the metal-alkyl bond and the primary FT products should be -olefins. These and other model projections are in agreement with experiment.