岳汉威
,
马振珠
,
包亦望
中国腐蚀与防护学报
pH=2.54, 5 mass%的硫酸铵溶液作为腐蚀介质，以干湿循环为条件，利用冲击球压法研究了混凝土冲击荷载-压痕尺寸、冲击应力-应变关系；对与冲击球压试验相关的其他物理量如抗压强度比、损伤区扩展、试件质量变化及溶液pH值变化等也进行了研究。研究发现冲击球压试验得到的混凝土冲击荷载-压痕尺寸关系曲线在低荷载范围呈双线性关系，且随着腐蚀作用的进行曲线斜率逐渐降低；冲击应力随着应变的增加而降低，且随着腐蚀作用的进行冲击应力-应变关系斜率整体降低。随着冲击荷载的增加，球头对混凝土表面造成的磨损、损伤以及局部变形程度远远高于荷载增加速率。在一定时间范围内，酸性硫酸铵溶液不会对混凝土的宏观力学性能产生较大的影响，但是发生的腐蚀反应却足以改变混凝土表面的性质。
关键词:
混凝土
,
surface
,
erosion
,
wetting-drying cycle
,
sphere impact
杨洪英潘颢丹佟琳琳刘媛媛
金属学报
doi:10.3724/SP.J.1037.2012.00279
在细菌浸出黄铜矿的过程中, 浸出速率缓慢的原因是矿物表面会形成一层阻碍矿物与浸出液之间物质交换的钝化膜, 这层膜的组成会随着浸出的进行而变化. 利用SEM, EDS, XRD和XPS等对细菌浸出黄铜矿的过程中, 矿物表面的形貌、组成及物相变化进行了研究. 结果表明, 黄铜矿在细菌浸出过程中依次形成了缺铁铜硫化物 Cu1-xFe1-ySz(x<y), 单质硫晶体S0, 氧化铁, 羟基氧化铁和黄钾铁矾. 由于浸矿混合细菌ASH-07对硫的氧化作用, 硫化物层和单质硫层都是氧化膜形成过程中的中间产物, 致密的黄钾铁矾层则对黄铜矿的浸出产生钝化作用.
关键词:
黄铜矿
,
passivation
,
surface
,
bacterial oxidation
,
jarosite
张林
,
徐送宁
,
张彩碚
,
祁阳
金属学报
应用分子动力学研究了一个熔融Cu55团簇冷却过程中变为二十面体的结构变化.
根据原子密度分布函数和对分布函数随温度变化的分析表明,
在降温过程中由于原子之间连续地交换位置, 团簇结构发生了三个阶
段的变化: 首先形成三壳层结构, 继之初步形成四壳层结构,
并在团簇内部开始形成由13个原子组成的二十面 体结构,
最终形成原子分布于4个壳层内具有二十面体结构的Cu$_{55}$团簇.
模拟中由原子密度分布函数确定了不同壳层的原子位置.
关键词:
Cu55团簇
,
molecular dynamics
,
computer simulation
,
surface
材料科学技术（英）
A 5 kW CW CO2 gas laser was used to produce NiCrBSi superalloy coatings. Powders were preplaced by plasma-spraying. The microstructure and chemical composition of the coating have been studied by SEM, XRD and HREM. The results show the coating microstructure is fine dendrites, composed of gamma matrix, gamma' and boride (NiB) eutectic, the lattice parameter of the gamma matrix is 0.3572 nm and there is a metallurgical bonding in interface.
关键词:
surface
Thin Solid Films
The finite element simulation uses an indenting wedge (apex angle, 136-degrees) as a two-dimensional approximation of the actual Vickers pyramid. The model assumes isotropic properties for the layer and substrate materials and an elastoplastic behaviour with a work-hardening characteristic. The stress distribution and the plastic deformation zone inside the layer as well as across the interface between film and substrate were calculated, Load-dependent Vickers hardness numbers obtained on TiN coatings, 8-mu-m thick on high speed steel, were compared with the finite element prediction for the wedge-shaped indenter. In the experiments results for the composite microhardness, the cross-sectional morphology of the residual impression and information on the quality of the interface adhesion were obtained. By the comparison of calculated and experimental hardness numbers, the yield stress of the TiN layer was found to be approximately 6 GPa.
关键词:
surface
黄均麟
,
万见峰
,
谢超英
物理测试
通过在钝化液中加入一种稀土氧化物制备成一种钝化镁粒，用SEM、XRD、AES分析了这种自制钝化镁粒表面层的成分和结构，发现其表面包覆均匀，致密，XRD和AES结果显示表面层主要含有CeO2和MgO。通过线扫描分析元素浓度沿包覆层方向的变化，大致估算了包覆层的厚度为7~8 μm。经测试其在1〖KG-*9〗000 ℃下的阻燃时间达到了25.7 s，较普通钝化镁粒阻燃时间有所提高。
关键词:
钝化镁粒
,
combustioninhibiting
,
surface
CHEN Niug
,
YU Zongsen University of Science and Technology Beijing
,
Beijing
,
China professor
,
Department of Materials Physics
,
University of Science and Technology Beijing
,
Beijing 100083
,
China
金属学报(英文版)
Si segregation was observed in the vacancy condensation pits,formed by supersaturated vacancies beneath the oxidation layer of Al-0.35wt-%Si alloy,by optical microscopy,X- ray photoelectron spectroscopy and microhardness tests.This phenomenon could only be explained by vacancy-Si complex inducing non-equilibrium segregation.
关键词:
non-equilibrium segregation
,
null
,
null
,
null
,
null
Shihong XU Pengshou XU Mingrong JI Xianming LIU Maosheng MA Jingsheng ZHU Yuheng ZHANG Structure Research Laboratory
,
University of Science and Technology of China
,
Hefei
,
230026
,
ChinaZhenjia XU Institute of Semiconductor
,
Academia Sinica
,
Beijing
,
100083
,
China
材料科学技术（英）
The alkali-metal Na adsorption on Si(100)2×1 surface and its promoted oxidation and Si oxide growth have been investigated by means of thermal desorption,work function,Auger electron spectroscopy and photoemission electron spectroscopy.The experimental data showed that there was a new state,interface electron state,near the Fermi level after the deposition of Na atoms.It was found that the presence of Na always caused an increase of the oxygen initial uptake whereas the promotion of Si oxide growth was observed only at the coverage of Na greater than 0.5 ML.A new mechanism of Na-promoted Si oxide growth is suggested in this paper.
关键词:
adsorption
,
null
,
null
,
null
Y.F.Hu
金属学报(英文版)
Polycrystalline silicon thin films were prepared by RTCVD (rapid thermal chemical vapor deposition) method on several substrates such as SSP (silicon sheet from powder) ribbon, poly-Si wafer and mono-Si wafer, lntra-granular defects such as stacking faults, twins and microstructure defects were investigated on thin films by scan electron microscopy (SEM) technique.
关键词:
poly-Si thin film
,
null
,
null
