排序方式: 共有80条查询结果,搜索用时 15 毫秒
1.
2.
《Optical Materials》2005,27(1):51-55
Long lasting alkaline earth silicates, Ca2MgSi2O7:Eu,Dy,Nd was prepared under a reduction atmosphere through solid state reaction. The obtained phosphor was characterized by means of X-ray diffraction (XRD) and photoluminescence spectrum (PLS). The crystal structure of Ca2MgSi2O7:Eu,Dy,Nd phosphor was refined by Rietveld analysis. The obtained Ca2MgSi2O7:Eu,Dy,Nd phosphor showed a yellow–green emission peaking at 518 nm, which is ascribed to the luminescent emission of the Eu2+ that occupied the octa-coordinated Ca2+ sites in the Ca2MgSi2O7 host. The electron affinity (ea) value for Eu2+ in [EuO8] was calculated to 1.9 eV. The decay profile and the emission spectrum indicated that when the value of Dy/Eu is increasing, there is a concentration quenching of Eu2+. 相似文献
3.
利用射频磁控溅射方法制备了具有CoSi2成分的非晶薄膜,对非晶薄膜的晶化过程进行了原位X射线分析。结果显示,溅射态薄膜为非晶态,而自由能一成分曲线说明非晶态合金有较低自由能。在非晶晶化过程中初生相为CoSi相,其形成由有效形成热(EHF)因素和结构因素决定。随加热温度升高,非晶薄膜晶化最终得到晶体CoSi2薄膜。 相似文献
4.
CHAI Feng YANG Cai-fu SU Hang ZHANG Yong-quan XU Zhou 《钢铁研究学报(英文版)》2007,14(3):56-62
The weldability of a low-carbon copper-bearing age hardening steel was evaluated using cracking suscepti- bility calculation, HAZ maximum hardness measurement, and Y-groove cracking evaluation test. The results show that the hardenability characteristics and cold cracking susceptibility of the steel are very low. The results also indicate that a crack-free weldment can be obtained during the welding of this type of steel even at an ambient temperature as low as -5 ℃ as well as in an absolute humidity lower than 4 000 Pa without any preheat treatment. A slight preheat treatment can prevent the joint from cracking when welding is carried out at lower ambient temperature or higher absolute humidity. 相似文献
5.
《Intermetallics》2013
Thermo-physical behavior of some Zr-based metallic glasses prepared by different molten quenching temperatures was studied by Differential scanning calorimetry (DSC) measurements. The characteristic thermo-physical properties are normally used for evaluating the glass-forming ability (GFA) of metallic glasses. Our results show that the glass transition temperature, crystallization temperature and supercooled liquid region of these metallic glasses increased with increasing the molten quenching temperature. Their glass-forming abilities were discussed in terms of the GFA criterion γ and the reduced glass transition temperature, Trg, using these thermo-physical properties. 相似文献
6.
《International Journal of Heat and Mass Transfer》2006,49(23-24):4437-4443
Molecular dynamics simulations are carried out to examine the bubble behavior confined in a nanochannel with particular emphasis on the nucleation phenomenon. Simple Lennard-Jones fluids are under consideration and nano-sized bubbles are observed under different conditions of solid–liquid interfacial wettability. It is found that the bubble nucleation behavior shows a marked dependence on the solid–liquid interfacial interaction. In particular, it is found that bubbles appear in the bulk liquid homogenously for a hydrophilic surface, but grow directly on a hydrophobic solid surface. Also, a bubble will not form on a non-wetting surface. A nanobubble exists stably under the equilibrium state and the number density distribution of the curved liquid–vapor interface is examined. It is also found that there are few vapor atoms in the nano-sized bubble and the internal vapor pressure of the nanobubble is much lower than that required from the Young–Laplace equation. The disagreement with the prediction of the Young–Laplace equation can be attributed to the fact that the liquid–vapor interface region plays an important role on the force balance at the curved liquid–vapor interface of a nanobubble. 相似文献
7.
Effect of melt heat treatment on the solid/liquid interface morphology of directional solidification
Yingwen Cai Guilin Zhang Jinshan Li Guang Chen Hengzhi Fu 《Science and Technology of Advanced Materials》2013,14(1):169-172
A set of quadral-electrode DC input voltage measure equipment was built up to detect the electrical resistance of Sb–Bi single-phase alloy. The results suggest that Sb–5%wt Bi undergoes structural transition in the temperature range of 730–750°C. By overheating the melt to different temperatures and then cooling to 690°C after a period of time, the samples are directionally solidified in a Bridgeman-type furnace. It is found for the first time that after heat treatment of the melt, the solid/liquid interface morphology shows significant variation depending on the speciic heat treatment. Also, in Ag–Cu, Al–Cu systems, bicrystal growth with different orientation is found to have different interface morphologies after heat treatment. It is believed that the evolution of the cluster size distribution in the melt contributes to these phenomena. 相似文献
8.
Guohua Wu Yu Fan Andrej Atrens Chunquan Zhai Wenjiang Ding 《Journal of Applied Electrochemistry》2008,38(2):251-257
The influence of Cl− and SO42− on the electrochemical behavior of AZ91D, AZCe2, and AZLa1 was studied. For all alloys, there was a current plateau in the
anodic polarization curves in Na2SO4 solutions. In 0.5% NaCl solution, there was a small current plateau, whereas there was none in the 3.5% and 5% NaCl solutions.
This indicated that SO42− is less aggressive than Cl−. The range of the current plateau decreased with increasing SO42− concentration. For all alloys, the high frequency capacitive loop in the Nyquist plots decreased with increasing concentration
consistent with the decrease in corrosion resistance with increasing Cl− and SO42− concentration. 相似文献
9.
10.
Effects of Zirconium on the chemical component and size distribution of Ti-bearing inclusions, favored the grain refinement of the welding reduced, coarse-grained heat affected zone (CGHAZ) with enhanced impact toughness in Ti-killed steels, which were examined based on experimental observations and thermodynamic calculations. It indicated that the chemical constituents of inclusions gradually varied from the TiO oxide to the Ti-O+Zr-O compound oxide and a single phase of the ZrO2 oxide, as the Zr content increased from zero to 0.0100%. A trace of Zr (0.0030%-0.0080%, depending on the oxygen content in liquid steel) provided a large amount of nucleating core for Ti oxide because of the larger specific density of ZrO2 oxide, and produced a small size distribution of the inclusions favorable for acicular ferrite transformation with a high nucleation rate in the CGHAZ, and a high volume fraction of acicular ferrite was obtained in the CGHAZ, with enhanced impact toughness. Otherwise, a high content of Zr (-0.0100%) produced a single phase Zr02, which was impotent to nucleate acicular ferrite, and a microstructure composed of ferrite side plate and grain boundary ferrite developed in the CGHAZ. The experimental results were confirmed by thermodynamic calculations. 相似文献