Photochemical synthesis of bimetallic Au-Ag nanoparticles with "core-shell" type structure by seed mediated catalytic growth

The colloidal Au core/Ag shell structure composite nanoparticles were synthesized in PEG-acetone solution by photochemical route. The monodispersed Au nanoparticles with average diameter of 3.9 nm were used as growth seeds. The optical property of colloids and the sizes of composite nanoparticles were characterized when the molar ratio of Au to Ag ranges from 4 : 1 to 1 : 4. The results show that a composite nanoparticle structure similar to strawberry shape is formed at the molar ratio of Au to Ag from 4 : 1 to 1 : 1; the composite nanoparticles consisting of a core of Au and shell of Ag were generated at the 1: 4 molar ratio, having a striking feature of forming interconnected network structure.     

Production of submicrocrystalline structure in large-scale Ti–6Al–4V billet by warm severe deformation processing

The “abc” deformation method for production of large-scale billets with submicrocrystalline structure was developed. A large billet of Ti–6Al–4V alloy (150-mm diameter × 200-mm length) with a homogeneous submicrocrystalline structure was produced. The refined structure with a grain/subgrain size of about 0.4 μm leads to a substantial mechanical properties improvement.     

超声波和稀土铈对化学镀Co-Ni-B合金镀层的改性作用

利用等离子发射光谱仪、电子能谱仪、X射线衍射仪、透射电子显微镜和显微硬度计等考察和分析了引入超声波和稀土金属铈时化学镀Co-Ni-B合金镀液的沉积速度、Co-Ni-B合金镀层的化学成分、晶体结构和显微硬度。结果表明，超声波和稀土金属铈的介入明显提高了化学镀Co-Ni-B合金的沉积速度，超声波的介入则提高了化学镀Co-Ni-B-Ce合金镀层中稀土铈的含量。在超声波和稀土铈的共同作用下，化学镀Co-Ni-B合金镀层的化学组成发生了改变，镀层结构由非晶态向微晶和晶态转化，镀层的显微硬度得到了较大的提高。     

组合模在车架纵梁生产中的应用

介绍了汽车车架纵梁的种类、结构特点、目前大型企业常用的几种生产方式及国际上的先进生产方法 ,并着重叙述了组合结构在车架纵梁生产中的应用     

钛阳极的制备及其纳米结构涂层的分析

采用热分解方法，先在钛基上制取铱钴氧化物底层，然后再被覆钌铱钛锡氧化物涂层，获得晶粒尺寸小于１０ｎｍ的涂层。     

Effect of copper addition on the thermal contraction of indium melt clusters

The structure of In-1%Cu and In-5%Cu (mass fraction) alloy melts were studied at different temperatures above liquidus by using a high-temperature X-ray diffractometer and were compared with that of pure In melt. Experimental results show that with the addition of 1% Cu or 5% Cu, the thermal contraction phenomenon of atom clusters occurs in melts with the temperature increasing like pure In melt. With the addition of 1% Cu, the thermal contraction of atom clusters increases and the contraction is not homogeneous in the whole measurement temperature range. The sudden change and noticeable contraction can be found in the range of 280-390℃. The temperature range of the sudden change is lower than that of pure In melt. With the addition of 5% Cu, the thermal contraction of atom clusters decreases and the contraction is not consistent in the whole measurement temperature range. The anomalous change can be measured at about 600 ℃. At the same superheating temperature, the nearest interatomic distance r1 of     

WC基硬质合金CVD涂层的组织与性能

利用X射线衍射研究了CP3型硬质合金涂覆 5层 (TiC TiNC TiC TiCN TiN)硬质层的组织 ,用扫描电镜观察了涂层的断口形貌 ,用划痕法测定了涂层与基体的结合力 ,用三点弯曲方法测定了涂覆前后硬质合金的抗弯强度 ,并用Weibull统计方法对其进行了分析。结果表明 :涂层组织由TiC ,TiC0 .2 N0 .8和TiN组成 ,涂层中无发达的柱状晶 ,涂层与基体结合良好 ,涂覆后硬质合金的抗弯强度有所下降 ,但分散性却减小     

Solid-state phase equilibria in the Gd–Co–Al ternary system at 1173 K

A portion of the isothermal section (1173 K) of the phase diagram of the Gd–Co–Al ternary system (up to 33.3 at.% Gd) were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS) techniques. Fourteen single-phase regions (including solid solution regions of the binary compounds), twenty-five two-phase regions and twelve three-phase regions were found to exist at this isothermal section. In the GdCo₂–GdAl₂ system, the existence of the GdCo_0.74Al_1.26 phase is identified and it has a composition range of 30–45 at.% Al, the maximum solid solubility of Al in GdCo₂ is about 15 at.%, and Co in GdAl₂ is about 16 at.%. Besides, the maximum solid solubility of Al in Co, Gd₂Co₁₇ and GdCo₅ is about 6, 17 and 25 at.%, respectively, the maximum solid solubility of Gd in Co, CoAl is below 2 at.% and the solid solubility range is from 47 to 61 at.% Al in CoAl phase. In this work, no new ternary compounds were observed.     

GCr15钢V型导轨裂纹分析

对V型导轨在磨削后出现的网状裂纹进行宏观和微观检验,分析裂纹产生的原因.结果表明,淬火加热温度偏高或加热时间过长,形成粗大的过热组织,即粗大针状马氏体和过热"带状组织",导致后序磨削产生网状裂纹.     

ZrO_2－Ni功能梯度材料界面结构的研究

利用透射电镜和高分辩电子显微术研究了ＺｒＯ_２－Ｎｉ功能梯度材料（ＦＧＭ）的界面形态与精细结构。结果表明，组元Ｎｉ和ＺｒＯ_２，以直接结合为主，无明显界面反应。ＺｒＯ_２中ｔ／ｍ相界完全共格，存在大量界面结构台阶。此外，在Ｎｉ孪晶界附近存在较多生长缺陷──Ｆｒａｎｋ位错。