Q.L.Deng1)
,
W.D.Huang1)
,
Y.H.Zhou1)
,
C.Y.Yu2)
,
Y.K.Zhang2)
,
Y.X.Tang2) and H.Zhang2) 1) State Key Lab .of Solidification Processing
,
Northwestern Polytechnical University
,
Xi’an 710072
,
China 2) Mechanical Department
,
Nanjing University of Aeronautics & Astronautics
,
Nanjing 210016
,
China
金属学报(英文版)
The mechanism oflasershock processing wasanalyzedinthispaper. Westudyexperimentallythelasershock processingon 2024 T62 aviation aluminium alloys. Theexperimental results show thefatiguelife of 2024 T62 aviation aluminium alloysshocked by a laserisimprovedgreatly.
关键词:
lasershock processing
,
null
,
null
李明涛
,
余慧玲
,
邓冬梅
,
冯振杰
,
曹世勋
,
张金仓
低温物理学报
本文报道了采用自助溶剂法对不同组分K0.8Fe2-ySe2单晶生长和结构研究的实验结果.X-射线衍射XRD（Cu靶和同步辐射）结构分析表明样品中存在两套衍射峰（分别对应相1和相2）,相1能够用ThCr2Si2结构,空间群I4/mmm（No.139）指标化,对应超导相.而相2能够用单一米勒指数（0 0l）标定,可能对应一个新的物相.相2的存在能够在不同组分的KxFe2-ySe2单晶样品中很好的重复.利用高分辨透射电子显微镜（TEM）研究了K0.8Fe2Se2样品的＂结构相分离＂特征,结果表明样品中存在明显的位错缺陷,可能与两相结构的竞争有关.对K0.8Fe2Se2单晶样品直流磁化测量表明相2可能为弱铁磁性,从而引起高温Tp～125K的ZFC与FC磁性反常.
关键词:
单晶生长
,
晶体结构
,
“245”-铁硒超导体
于萍
,
王亚权
腐蚀学报（英文）
研究了添加0.1mass%稀土Y的铸造K38G高温合金在1000℃的恒温氧化行为.结果表明,较之不含Y的合金，含Y铸态K38G合金的氧化速率显著降低； 氧化时形成双层的外氧化膜，表层为以Cr2O3和TiO.2为主的混合氧化物层，内层为连续的Al2O3层；没有内氧化和内氮化，没有氧化膜的剥落，加入稀土Y有效地提高了氧化膜的粘附性能.
关键词:
高温氧化
,
null
,
null
,
null
于萍
,
王亚权
腐蚀学报（英文）
doi:10.3969/j.issn.1002-6495.2007.03.010
研究了添加0.1 mass%稀土Y的铸造K38G高温合金在1000℃的恒温氧化行为.结果表明,较之不含Y的合金,含Y铸态K38G合金的氧化速率显著降低;氧化时形成双层的外氧化膜,表层为以Cr2O3和TiO2为主的混合氧化物层,内层为连续的Al2O3层;没有内氧化和内氮化,没有氧化膜的剥落,加入稀土Y有效地提高了氧化膜的粘附性能.
关键词:
高温氧化
,
K38G
,
高温合金
,
稀土元素
,
Y
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
Journal of Physics and Chemistry of Solids
The layered ternary ceramics Ti3SiC2 and Ti3AlC2 are isostructural and can form Ti3Si1-xAlxC2 solid solutions combining the advanced properties of both compounds [H.B. Zhang, Y.C. Zhou, Y.W. Bao, M.S. Li, Improving the oxidation resistance of Ti3SiC2 by forming a Ti3Si0.90Al0.1C2 solid solution, Acta Mater. 52 (2004) 3631-3637; E.D. Wu, J.Y. Wang, H.B. Zhang, Y.C. Zhou, K. Sun, Y.J. Xue, Neutron diffraction studies of Ti3Si0.9Al0.1C2 compound, Mater. Lett. 59 (2005) 2715-2719; J.Y. Wang, Y.C. Zhou, First-principles study of equilibrium properties and electronic structure of Ti3Si0.75Al0.25C2 solid solution, J. Phys.: Condens. Matter 15 (2003) 5959-5968; Y.C. Zhou, J.X. Chen, J.Y. Wang, Strengthening of Ti3AlC2 by incorporation of Si to form Ti3Al1-xSixC2 solid solutions, Acta. Mater. 54 (2006) 1317-1322]. In the present work, the solid solutions of Ti3Si1-xAlxC2 (x = 0, 0.25, 0.33, 0.5, 0.67, 0.75, 1) are investigated by first-principle calculations based on pseudo-potential plan-wave method within the density functional theory framework. The results show that as Al content increases in the solid solution, all the bonds have weakened to certain extents, which lead to an unstable structure both energetically and geometrically. The calculated results are compared and discussed with the reported data for the Ti3Si1-xAlxC2 solid solutions. (c) 2007 Elsevier Ltd. All rights reserved.
关键词:
ceramics;ab initio calculations;electronic structure;electrical;conductivity;oxidation behavior;mechanical-properties;ti3sic2;temperature;ti3alc2;air;si
沈雅明
,
刘正堂
,
冯丽萍
,
刘璐
,
许冰
稀有金属材料与工程
采用射频磁控溅射法制备HfSi_xO_y薄膜,系统研究工艺参数对HfSi_xO_y薄膜沉积速率的影响规律.对沉积态和退火HfO_2和HfSi_xO_y薄膜的结构进行了对比分析.结果表明:HfSi_xO_y薄膜的沉积速率随射频功率、Ar气体流量和粘贴Si面积的增大而增大,随溅射气压的增大而减小.衬底未加热时,制备的HfSi_xO_y和HfO_2薄膜均呈非晶态,随着衬底加热温度的上升,HfO_2薄膜呈多晶态,而HfSi_xO_y薄膜呈非晶态.HfSi_xO_y薄膜在800℃退火后仍呈非晶态,而HfO_2薄膜在400℃退火后已明显晶化,这表明HfSi_xO_y薄膜具有较高的热稳定性.
关键词:
高K栅介质
,
HfSi_xO_y薄膜
,
射频磁控反应溅射
,
沉积速率
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
,
null
,
null
,
null
Chemical Physics Letters
The complete high-order perturbation formulas of EPR parameters (g-shifts Delta g(parallel to),Delta g(perpendicular to) and zero-field splitting D), including not only the crystal-field (CF) mechanism, but also the charge-transfer (CT) mechanism (which is neglected in crystal-field theory), are established by a cluster approach for 3d(2) ions in trigonal symmetry. From these formulas, the EPR parameters of Y2SiO4:Cr4+, Ba-3(VO4)(2):Mn5+ and K2CrO4:Fe6+ are calculated. The results are in reasonable agreement with the observed values. It is found that the relative importance of CT mechanism increases with increasing atomic number of 3d(2) ion and so in the studies of EPR parameters for high valence state 3d" ions in crystals, both CF and CT mechanisms should be taken in account. (c) 2005 Elsevier B.V. All rights reserved.
关键词:
transition-metal-complexes;atomic screening constants;tetrahedral;mn5+;oxo coordination;scf functions;ions;spin;spectroscopy;laser;field
