L.J.Shang1 2)
,
Y.Wang2)
,
Q.K.Cai1)and C.S.Liu1) 1) Northeastern University
,
Shenyang 110006
,
China 2) Shenyang University
,
Shenyang 110044
,
China
金属学报(英文版)
Onthebase of 20 # steel, Co base alloy with Ce and without Ce was obtained with laser heatingtechnology. Theresultshowsthat Cehasobviouslyeffecton alloy microstructureespe ciallyimprovethecorrosion resistancein acid by31 % ,oxygenation resistanceby23 % ,in al kalescent liquid by 23 % . Improve fearlessness 30% and improve hardness by 168 HV.Throughcontrast and analysison the Co base microstructure with Ce and without Ce . The paper discussthetheory of Ce modification Co base alloy from theside of cooling thermody namicsand dynamics
关键词:
rareearth
,
null
,
null
,
null
J.S.Wang1
,
2)
,
M.L.Zhou2)
,
J.X.Zhang2)
,
Z.R.Nie2) T.Y.Zuo2) and G.J.Zhang2) 1) State Key Laboratory of Materials Chemistry and Applications
,
Peking University
,
Beijing 100871
,
China2) Schoolof Materials Science and Engineering
,
Beijing Polytechnic University
,
Beijing 100022
,
China
金属学报(英文版)
The valenceofelementyttrium of Y2 O3 Mocathode materialhasbeenstudied by usingther mal weight analysis, X ray diffraction analysis, Scanning electron microscopy and X rayphotoelectronspectrum . It hasbeen provedthatyttrium oxidecan bereduced by molybdenum carbide. Thereaction between powdered Y2 O3 and Mo2 Ccan happen at 1173 , and Y2 O3may bereduced to metallicyttrium . Afterthepowder mixtureof Y2 O3 and Mo2 Cwasheat treated at1873 K, Yttrium existsin two kinds of chemicalstate- yttrium of zero valence and yttrium ofthreevalences.
关键词:
valence
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null
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null
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null
Journal of the European Ceramic Society
Y(2)SiO(5) is a promising candidate for oxidation-resistant or environmental/thermal barrier coatings (ETBC) due to its excellent high-temperature stability, low elastic modulus and low oxygen permeability. In this paper, we investigated the thermal properties Of Y2SiO5 comprehensively, including thermal expansion, thermal diffusivity, heat capacity and thermal conductivity. It is interesting that Y(2)SiO(5) has a very low thermal conductivity (similar to 1.40 W/m K) but a relatively high linear thermal expansion coefficient ((8.36 +/- 0.5) x 10(-6) K(-1)), suggesting compatible thermal and mechanical properties to some non-oxide ceramics and nickel superalloys as ETBC layer. Y(2)SiO(5) is also an ideal EBC on YSZ TBC layer due to their close thermal expansion coefficients. As a continuous source of Y(3+), it is predicted that Y(2)SiO(5) EBC may prolong the lifetime of zirconia-based TBC by stopping the degradation aroused by the loss of Y stabilizer. (C) 2008 Elsevier Ltd. All rights reserved.
关键词:
Y(2)SiO(5);Thermal properties;Silicate;Thermal conductivity;Engine;components;yttrium silicate;barrier coatings;si3n4 ceramics;temperature;expansion;nitride;si3n4-sio2-y2o3;conductivity;corrosion;system
郑永挺
,
韩杰才
,
杜善义
金属学报
doi:10.3321/j.issn:0412-1961.2000.02.021
采用燃烧合成工艺,在超高压氮气下,制备了具有较高致密度的AlN/Y2O3陶瓷.研究表明,Al-N2-Y2O3的自蔓延高温合成(SHS)过程为:660℃Al熔化,1000℃Al剧烈挥发并与N2迅速反应形成AlN,放出大量热;当反应温度升至1720℃时,Y2O3与Al2O3形成共晶液相Al5Y3O12,发生液相烧结高温液相烧结使产物的致密度显著提高,但由于其阻碍N2向反应前沿的渗透,产物中残余Al含量增加.随着Y2O3含量的增加,液相烧结作用增强,产物致密度显著提高,抗弯强度及断裂韧性提高.Al-N2-Y2O3体系的SHS致密化主要发生在燃烧波蔓延方向,具有明显的方向性.
关键词:
AlN陶瓷
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烧合成
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2O3
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gas HIP
Journal of the European Ceramic Society
Y2SiO5 has potential applications as functional-structural ceramic and environmental/thermal barrier coating material. As an important grain-boundary phase in the sintered Si3N4, it also influences the mechanical and dielectric performances of the host material. In this paper, we present the mechanical properties of Y2SiO5 including elastic moduli, hardness, strength and fracture toughness, and try to understand the mechanical features from the viewpoint of crystal structure. Y2SiO5 has low shear modulus, low hardness, as well as high capacity for dispersing mechanical damage energy and for resisting crack penetration. Particularly, it can be machined by cemented carbides tools. The crystal structure characteristics of Y2SiO5 suggest the low-energy weakly bonded atomic planes crossed only by the easily breaking Y-O bonds as well as the rotatable rigid SiO4 tetrahedra are the origins of low shear deformation, good damage tolerance and good machinability of this material. TEM observations also demonstrate that the mechanical damage energy was dispersed in the form of the micro-cleavages, stacking faults and twins along these weakly bonded atomic planes. which allows the "microscale-plasticity" for Y2SiO5.
关键词:
Y2SiO5;mechanical properties;damage;strength;fracture;yttrium silicate;ceramics;system;si3n4-sio2-y2o3;coatings;monazite;strength;phases
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
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null
,
null
孙义海
,
张玉峰
,
郭景坤
无机材料学报
通过在2Y-TZP中加入一定量的硅酸盐玻璃相添加剂,在较低的烧结温度下,制备出细晶、具有良好综合性能的2Y-TZP材料.研究了添加剂加入后,2Y-TZP材料烧结特性、显微结构及力学性能.发现加入少量的添加剂后,不但可以明显降低材料的烧结温度,而且由于细晶及相变增韧的共同作用,材料仍具有较高的抗折强度和断裂韧性.讨论了稳定剂含量对低温烧结Y-TZP力学性能的影响,发现较低稳定剂含量的2Y-TZP材料,由于临界相变尺寸小,在断裂过程中,有更多的四方相氧化锆转变成单斜相,相变增韧的效果更好,因而具有更高的断裂韧性.
关键词:
Y-TZP
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stabilizer
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additives
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low temperature sintering
,
critical transformation size
