A.Cantarel
,
E.Lacoste
,
O.Mantaux
,
E.Arquis
,
M.Danis
材料科学技术（英文）
Injection of liquid alloy through a fibrous preform located in an initially preheated mould is a classical method used to process metal matrix composites (MMCs). In order to reduce the chemical reactions between the fibres and the metal matrix, the fibrous reinforcement and the mould are commonly preheated up to initial temperatures much lower than the metal solidification temperature. Therefore, metal solidification instantaneously occurs on fibre contact during composites infiltration. Unlike what happens when infiltrating a pure metal, temperature and composition are able to vary within the matrix; these heterogeneities induce macrosegregation within composites...
关键词:
Segregation
,
null
,
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
Journal of Applied Physics
Mn(2)O(3)/Mn(3)O(4) nanoclusters were prepared by air oxidation of Mn(3)O(4) nanoparticles. The nanoparticles located at the surface of the Mn(2)O(3)/Mn(3)O(4) nanoclusters are oxidized to Mn(3)O(4) to form the special structure of the Mn(2)O(3)/Mn(3)O(4) nanoclusters. An exchange bias was observed in the Mn(2)O(3)/Mn(3)O(4) nanoclusters, which was induced by exchange coupling between ferromagnetic Mn(3)O(4) and antiferromagnetic Mn(3)O(4) phases. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3055349]
关键词:
mn3o4;nanoparticles;anisotropy;particles;nanorods;mn2o3
XU Xiuguang WANG Changzhen TU Ganfeng Northeast University of Technology
,
Shenyang
,
China.
材料科学技术（英文）
Thermodynamic properties of 3Y_2O_3·5Al_2O_3 double compound have been determined with CaF_2 single crystal electrolyte galvanic cell at 1049 K to 1230 K.The galvanic cell used can be expressed as: Pt,O_2(g)丨Y_2O_3(s),YOF_((s))丨CaF_2丨YOF_((s)), 3Y_2O_3·5Al_2O_(3(s))丨Al_2O_(3(s))丨O_2(g),Pt, of which the cell reaction is; 3Y_2O_(3(s))+SAl_2O_(3(s))=3Y_2O_3·SAl_2O_(3(s)) The following result is obtained: A_fG°(3Y_2O_3·5Al_2O_3)=-939500+765.90T±710J/mol where,△fG°(3Y_2O_3·5Al_2O_3)is the free energy of formation of 3Y_2O_3·5Al_2O_3 from Y_2O_3 and Al_2O_3.
关键词:
rare earth
,
null
,
null
王新华
,
古山贞夫
,
福泽章
金属学报
用示差热分析(DTA)和X射线衍射(XRD)方法测定Na_2O—Ga_2O_3(>50mol％Ga_2O_3)系相平衡图结果表明,该二元系中有Na_2OGa_2O_3,2Na_2O 3Ga_2O_3,Na_2O 3Ga_2O_3和Na_2O 5Ga_2O_3四个中间化合物2Na_2O 3Ga_2O_3在温度高于976±8℃时分解为Na_2O Ga_2O_3和Na_2O 3Ga_2O_3 Na_2O Ga_2O_3,Na_2O 3Ga_2O_3和Na_2O 5Ga_2O_3均为异分熔化化合物,其熔化分解温度分别为1382±1℃,1285±5℃和1417±4℃给出了新发现的化合物2Na_2O·3Ga_2O_3和Na_2O_3 Ga_2O_3的X射线衍射特征数据
关键词:
Na_2O
,
Ga_2O_3
,
Na_2O·Ga_2O_3
,
2Na_2O·3Ga_2O_3
,
Na_2O·3Ga_2O_3
,
Na_2O·5Ga_2O_3
,
phase relation
,
phase diagram
,
null
,
null
,
null
,
null
E.E.Shaisha
,
Sh.F.El-Desouki
,
I.Shaltout
,
A.A.Bahgat
材料科学技术（英文）
A new glass system (Bi2O3)50(Fe2O3)10(Li2O)x(K2O)40-x, where x changes in steps of 5 mole fraction between 0 and 40, was selected to study the electrical relaxation and the mixed alkali effect (MAE) phenomena. Measurements of ac conductivity σac, dielectric permittivity ε' and loss factor tan± in the frequency range of 0.12~102 kHz and in the temperature range of 300~650 K were carried out. The temperature dependence of the ac conductivity shows a slow increasing rate at low temperature and high frequency and a rapid increase at high temperature and low frequency. At constant temperature, the ac conductivity is found to be proportional to ωs, where s is the frequency exponent, which is less than 1. Analysis of the conductivity data and the frequency exponent shows that the overlapping large polaron tunnelling (OLPT) model of ions is the most favorable mechanism for the ac conduction in the present glass system. The ac response, the dc conductivity and dielectric relaxation have the same activation energy and they originate from the same basic transport mechanism. The results of the dielectric permittivity show no maximum peak in the temperature and frequency range studied. This absence of maximum peak is an indication of non-ferroelectric behavior of all the studied samples. The MAE has been detected in the ac conductivity, which is the same as the classical MAE in the dc conductivity. The electrical parameters such as dielectric permittivity ε' and real dielectric modulus M' show a typical minimum deviation from linearity by about two orders of magnitude. The loss factor tanδ and the imaginary dielectric modulus M" are insignificantly dependent on composition even at the same transition temperature Tg.
关键词:
Dielectric permittivity
,
null
,
null
,
null
殷海荣
,
武丽华
,
陈福
,
安百江
硅酸盐通报
doi:10.3969/j.issn.1001-1625.2006.04.035
制备了Na2O-Al2O3-B2O3系统低熔点玻璃,确定了Na2O-Al2O3-B2O3系统玻璃成玻范围,研究了玻璃的转变温度(Tg)、热膨胀系数(α)和玻璃的红外光谱,表明这种玻璃的熔化温度低、转变温度也较低、玻璃的热膨胀系数较大,在近红外区有一水分的吸收带,在中红外区有B-O、Al-O的特征吸收带,以及玻璃的Tg、α与玻璃组成的关系.
关键词:
硼酸盐玻璃
,
低熔点玻璃
,
热性质
,
红外光谱
徐天华
,
赵越
,
孙彬
,
付恒磊
,
宋伟
功能材料
为进一步优化ZnCr2O4-V2O5-Li2O-ZnO湿敏材料的性能,对制备工艺做了3点改进:在玻璃相V2O5-Li2O-ZnO中掺加SiO2,将晶相原料进行高温烧结；重新筛选烧结制度；测试了样品感湿特性,取得了预期效果.在分析样品微观结构的基础上,对实验结果作了理论解释.
关键词:
湿敏材料
,
晶相
,
玻璃相
,
感湿特性
Lin LI
,
Zhujun TANG
,
Weiying SUN
,
Peiling WANG
材料科学技术（英文）
Rare earth oxide systems Al2O3-La2O3 and SiO2-La2O3 were thermodynamically assessed and optimized with the substitution model. The obtained model parameters and Gibbs free energy of line compounds and pure components were applied to the prediction of the liquidus surface and isothermal sections of Al2O3-SiO2-La2O3 system.
关键词:
