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Preparation and Properties of Sintering Additives Coated Si3N4 from Heterogeneous Nucleation Processing

Juxian ZHANG , Jinjun FENG , Longqiao GAO

材料科学技术(英文)

The sintering additives such as Al2O3 and/or Y2O3 were coated on the surfaces of Si3N4 particles via heterogeneous nucleation processing using a buffered pH solution as the precipitation reagent. They nucleated and grew only on the surfaces of Si3N4 and did not form sol particles in solution by TEM observation. The isoelectric point (IEP) of coated Si3N4 was different from that of as-received Si3N4. The IEP of Al(OH)3-coated Si3N4 occurred at pH8.4, which is close to that of alumina. When Al(OH)3-coated Si3N4 particles were coated with Y(OH)3, the IEP of coated Si3N4 powder shifted from pH8.4 to pH9.2, similar to that of yttria. In addition, the rheological data showed that Al2O3 and/or Y2O3 coated Si3N4 suspension is nearly Newtonian and that added Si3N4 suspension shows a shear rate thinning behavior.

关键词: Si3N4 powder , null , null , null

Al2O3-Coated Nano-SiC Particles Reinforced Al2O3 Matrix Composites

Juxian ZHANG , Jinjun FENG , Longqiao GAO

材料科学技术(英文)

Properties of Al2O3-coated nano-SiC have been compared with those of as-received SiC. The isoelectric point (IEP) of SiC changed from pH3.4 to pH7.3 after coating with the alumina precursor, which is close to that of alumina. Because both surfaces of coated SiC and Al2O3 possess higher positive charge at pH=4.5~5.0, they are uniformly dispersed in the two-phase aqueous suspensions, Then a mixed powder containing nano-SiC dispersed homogeneously into the Al2O3 matrix was achieved from flocculating the two-phase suspension. Finally, Al2O3/SiC nanocomposites were obtained by coating nano-SiC with Al2O3, in which the majority of SiC particles were located within the Al2O3 grains. The observation by transmission electron microscopy (TEM) and the analysis by the X-ray photoelectron spectroscopy (XPS) showed that cracks propagated towards the intragranular SiC rather than along grain boundaries.

关键词: Coated nano-SiC , null , null , null

Ion sputter erosion in metallic glass-A response to "Comment on: Homogeneity of Zr(64.13)Cu(15.75)Ni(10.12)Al(10) bulk metallic glass" by L-Y. Chen, Y-W. Zeng, Q-P. Cao, B-J. Park, Y-M. Chen, K. Hono, U. Vainio, Z-L. Zhang, U. Kaiser, X-D. Wang, and J-Z Jiang J. Mater. Res. 24, 3116 (2009)

Journal of Materials Research

The morphology of the dark and bright regions observed by transmission electron microscopy for the Zr(64.13)Cu(15.75)Ni(10.12)Al(10) bulk metallic glass strongly depends on the ion beam parameters used for ion milling. This indicates that the ion beam could introduce surface fluctuation to metallic glasses during ion milling.

关键词: room-temperature

Broer-Kaup-Kupershmidt方程的新精确解

杨立娟 , 杨琼芬 , 杜先云

量子电子学报 doi:10.3969/j.issn.1007-5461.2012.02.003

CK方法是求解非线性发展方程的一种有效的直接方法.利用推广的CK方法,求得(2+1)维Broer-Kaup-Kupershmidt方程的Backlund公式,从而获得方程的大量新的精确解,推广了Xu和Zhang的结果.

关键词: 非线性发展方程 , Broer-Kaup-Kupershmidt方程 , 精确解 , CK方法 , Backlund变换

Three-dimensional (3D) Ising universality in magnets and critical indices at fluid-fluid phase transition

Phase Transitions

Experimental data for critical exponents in some magnetic materials are compared with recent theoretical results on the three-dimensional (3D) Ising model, as derived by one of us (ZDZ) based on two conjectures [Z.D. Zhang, Conjectures on the exact solution of three-dimensional (3D) simple orthorhombic Ising lattices, Phil. Mag. 87 (2007), pp. 5309-5419]. It is found that critical exponents in some bulk magnetic materials indeed form a 3D Ising universality. Our attention is then focused on the critical indices at fluid-fluid phase transition. We suggest to use Zhang's exponent = 3/8 to fit the experimental data over the wider asymptotic region near the critical point of a fluid-fluid phase transition. The 3D Ising universality should exist for critical indices in a certain class of magnets and at fluid-fluid phase transition.

关键词: magnetically ordered materials;fluid-fluid;phase transitions;order-disorder effects;ferromagnetic curie temperature;liquid critical phenomena;x-ray-scattering;critical exponents;critical-point;coexistence;curves;binary-solutions;ionic-solutions;behavior;equation

Response to the Comment on 'Conjectures on exact solution of three-dimensional (3D) simple orthorhombic Ising lattices'

Philosophical Magazine

The error of Equation (15b) in my article [Z.D. Zhang, Phil. Mag. 87 (2007) p.5309] in the application of the Jordan-Wigner transformation does not affect the validity of the putative exact solution, since the solution is not derived directly from that equation. Other objections of Perk's comment [J.H.H. Perk, Phil. Mag. 89 (2009) p.761] are the same as those in Wu et al.'s comments [F.Y. Wu et al., Phil. Mag. 88 (2008) p.3093; p.3103], which do not stand on solid ground and which I have sought to refute in my previous response [Z.D. Zhang, Phil. Mag. 88 (2008) p.3097]. The conjectured solution can be utilized to understand critical phenomena in various systems, whereas the conjectures are open to rigorous proof.

关键词: 3D Ising model;exact solution;conjecture;critical phenomena;ferromagnetism;magnetic phase transition;model;analyticity

不同掺杂的钇系-123薄膜磁通特性

张鹰子 , 王志 , 向建勇 , 闻海虎

低温物理学报 doi:10.3969/j.issn.1000-3258.2005.z1.087

我们在磁场中分别测量了最佳掺杂的YBa2Cu3O7-δ、钙0.2掺杂的Y1-xCaxBa2Cu3O7-δ及钙0.5掺杂的Pr1-xCaxBa2Cu3O7-δ薄膜的电阻温度关系.利用最近Zhang et al. [Phys. Rev. B 71(2005), 052502 ]提出的热激活能的分析方法对薄膜的磁通特性进行了分析、比较与讨论.

关键词: Y-123薄膜 , 涡旋特性 , 激活能

1998 COMPREHENSIVE TABLE OF CONTENTS

中国腐蚀与防护学报

N。1Atmospheric Corrosivlty for Steels………………………………………………… .LIANG Caideng HO[I i。-tat(6)Caustic Stress Corrosion Cr。king of Alloy 800 Part 2.The Effect of Thiosul执e……………………………………… KONG De-sheng YANG Wu ZHAO Guo-zheng HUANG De.ltL。ZHANG Yu。。he CHEN She。g-bac(13)SERS slid E16CttOCh6iniC81 Stlldy Of Illhibit1Oli M6ch&tllsth Of ThlollY68 Oil ITOll ID H....

关键词:

Proposed magnetic equation of state for the three-dimensional Ising model near criticality: Is the insulating ferromagnet CrBr(3) a candidate?

Physics Letters A

In a magnetic system, consistent with Griffiths analyticity requirements one can parameterize the equation of state near criticality by writing H = r(beta delta)h(theta), T = rt(theta) and the magnetization M = r(beta)m(theta), where T is measured from the critical temperature. For the insulating ferromagnet CrBr(3), the experimental data of Ho and Litster [J.T. Ho, J.D. Litster, Phys. Rev. Lett. 22 (1969) 6031 is well fitted by m(theta) as a linear function of theta [P. Schofield, J.D. Litster, J.T Ho, Phys. Rev. Lett. 23 (1969) 1098]. Also Ho and Litster give beta = 0.368, gamma = 1.215 and delta = 4.3. Those critical experiments are very close to the recent 31) king results of Zhang [Z.D. Zhang, Philos. Mag. 87 (2007) 5309], namely beta = 3/8, gamma = 5/4 and delta = 13/3. We therefore predict that m(theta) will be proportional to theta as a fingerprint of the 3D Ising Hamiltonian. (C) 2009 Elsevier B.V. All rights reserved.

关键词: Critical-point effects;Critical exponents;Ising model;Criticality;Ferromagnet;Magnetic equation of state;critical exponents

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