B.W. Wang
,
H. Shen
金属学报(英文版)
Ni-Cr System solar selective thin solid films were prepared by d.c. magnetron reactivesputtering under the atmosphere of O2 and N2. Ni-Cr alloy was chosen as targetmaterial and copper sheets as substrate. Using SEM, Spectrophotometer and Talystepto analyze the relations between the selective characteristic and the structure, theformation and the thickness of the thin films. The aim is to obtain good solar selectivethin films with high absorptance and low emittance, which is applied to flat plate solarheat collectors.
关键词:
solar selective thin film
,
null
,
null
,
null
Journal of the European Ceramic Society
gamma-Y2Si2O7 is a promising candidate both for high temperature structural applications and as thermal barrier coatings due to its unique combination of properties, such as high melting point, good machinability, high thermal stability, low linear thermal expansion coefficient (3.9 x 10(-6) K-1, 25-1400 degrees C) and low thermal conductivity (< 3 W/m K above 300 degrees C). In this work, the hot corrosion behavior of gamma-Y2Si2O7 in strongly basic Na2CO3 molten salt at 850-1000 degrees C for 20 h in flowing air was investigated. In the employed conditions, multi-layer corrosion scales with total thickness less than 90 mu m were formed. At 850-900 degrees C, the outmost layer of the scale was composed of the reprecipitation Of Y2O3, the bottom of a Si-rich Na2O center dot xSiO(2) (x > 3.65) melt layer, and the middle of a NaYSiO4 layer. At 1000 degrees C, the corrosion products turned out to be a mixture of NaY9Si6O26 and Si-rich Na2O center dot xSiO(2) (x > 3.65). In all cases, a thin layer of protective SiO2 formed under the Na2O center dot XSiO2 melt and protected the bulk material from further corrosion. (c) 2007 Elsevier Ltd. All rights reserved.
关键词:
Y2Si2O7;corrosion;silicates;structural applications;engine;components;yttrium silicate coatings;oxidation protection;alkali corrosion;si3n4;ceramics;nitride;composites;na2so4;solubility;disilicate;mechanism
Journal of Physical Chemistry C
We report the controlled synthesis of four kinds of cobalt basic salts with different morphologies and colors (pink, blue, green, and lavender) using urea as a hydrolysis agent in the presence of block copolymer P123. Li2SO4 and LiCl were used as salt additives to control the type of cobalt basic, salts. It was found that the amount of urea plays a critical role in the synthesis of cobalt basic salts with different phases. Two of them exhibit interesting three-dimensional urchinlike and flowerlike morphology assembled from nanorods (pink) and nanosheets (blue), respectively. The present work suggests that it is possible to directly grow three-dimensional-ordered assemblies built from one-dimensional or two-dimensional cobalt basic salt narrostructures through a one-step aqueous solution-phase chemical route under controlled conditions.
关键词:
alpha-nickel hydroxide;superstructures;carbonate;nanoparticles;conversion;bacro4;co3o4
Wei GUO
,
Yaping ZONG
,
Gang WANG
,
Liang ZUO
材料科学技术（英文）
The effects of applied tensile strain on the coherent α2 →O-phase transformation in Ti-Al-Nb alloys are explored by computer simulation using a phase-field method. The focus is on the influence of the applied strain direction on the microstructure and volume fraction of the O-phase precipitates. It is found that altering applied strain direction can modify microstructure of Ti-25Al-10~12Nb (at.~pct) alloy duringα2 →O-phase transformation effectively and full laminate microstructure in the Ti-25Al-10Nb (at. pct) alloy can be realized by an applied strain only along the direction 30° away from theα2 phase <10 0> in magnitude equivalent to the stress-free transformation strain. The simulation also shows that not only the magnitude of applied strain but also the applied strain direction influences the O-phase volume fraction and the effect of strain direction on the volume fraction is up to 25%.
关键词:
Phase field simulation
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null
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null
Journal of Alloys and Compounds
The subsolidus phase relations in the system La2O3-B2O3-P2O5 were investigated. The system can be divided into 12 three-phase regions. There are nine binary compounds and one ternary compound in this system. The ternary compound La7O6(BO3)(PO4)(2) has a monoclinic structure, space groups P2(1)/n, with lattice constants a = 7.0172 Angstrom, b = 17.9125 Angstrom, c = 12.6500 Angstrom, beta = 97.516 degrees, V = 1576.39 Angstrom(3), and Z = 4.
关键词:
La2O3-B-3-B2O3-P2O5 system;phase relations;ternary compounds
陈玮
,
姚长江
,
尹周澜
,
刘新红
耐火材料
doi:10.3969/j.issn.1001-1935.2008.04.009
分别对反应前后的p-Al2O3进行XRD及SEM分析,确定反应前后Al2O3的物相及显微结构变化;测定加入添加剂前后浆体温度与时间的关系,从而确定添加剂对p-Al2O3水化速度的影响;测定加入添加剂前后浆体的黏度变化,从而测定出添加剂对p-Al2O3水化过程的影响.结果表明:1)p-Al2O3属于无定形态;2)在没有添加剂的情况下,p-Al2O3的水化速率很快,同时释放出大量热量,水化产物主要是一水软铝石、三水铝石和拜耳石;3)加入碳酸钠及六偏磷酸钠的混合物为添加剂后,p-Al2O3的水化速率显著降低,释放出的热量显著降低,水化产物主要是一水软铝石.
关键词:
p - 氧化铝
,
水化硬化
,
不定形耐火材料
,
结合剂
G.C. Jiang
,
K. Tang
,
X.B. Zhang and K.D. Xu Shanghai Enhanced Laboratory of Ferrometallurgy
,
Shanghai University
,
149 Yanchang Road
,
Shanghai 200072
,
China
金属学报(英文版)
Model Investigation is the only feasible way to solve the problem about the component activities in concentrated multicomponent alloys and molten slags at present. The basic characteristic of SELF-SReM model is briefly introduced in this paper. It intends to give out the systematical value of component activities in the whole homogeneous region of a concentrated multicomponent melt, then to provide a reliable database for the description of the equilibrium conditions associated with metallurgy processes. For molten slags, the key issue is to distinguish the accuracy of thermodynamic properties in binary systems. The fundamental approach for this task is to link the microscopic bond structure and macroscopic activity based on both of the measurement of high tem- perature Raman spectroscopy and the corresponding computation simulation according to molecular dynamics and quantum chemistry.
关键词:
activity
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null
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null
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null
ZHAO Hongzhuang
,
Seokjae LEE
,
Youngkook LEE
,
LIU Xianghua
,
WANG Guodong
钢铁研究学报(英文版)
This study aims at the experimental analysis of the transformation induced plasticity (TRIP) phenomenon. Experiments are conducted in which martensite is allowed to grow under the influence of a series of externally applied stresses. The magnitude of the applied stresses is less than 67% of the yield strength of austenite σγ(Ts). Since there is no obvious difference between the transformation plasticity under tension and the compression for the lower applied stresses, only compressive stresses are applied. The results confirm that the transformation plasticity is proportional to the applied stress if the latter does not exceed 67% of σγ(Ts). The TRIPstrain, the kinetics, and their dependence on the applied stresses are studied. The comparison between calculated results and experimental results shows that the model accurately describes the phenomenon.
关键词:
applied stress;TRIP;martensite transformation;lowalloy steel
