M.C.Huang
,
C.H.Gao
,
L.G.Huang
金属学报(英文版)
The microscopic structure change rule in high speed steel (HSS) after an additional cryogenic treatment was studied in this paper. Highly dispersed nano-carbide (η-Fe2C)separated from tempering martensite was found distributed on twin planes of martensite and dislocation places. Retained austenite was found sheared into martensite and nano-carbide separated at the same time. In addition, the tempering martensite was fine-grained. The stated changes of HSS evidently improve the lifespan of HSS cutter and fully show the advantages of nano-structure. The cryogenic treatment of HSS also improves the roughness of HSS cutter (decrease Ra number by about 50) and greatly increases the wear resistance of HSS cutter. Further experiments on the wear characteristic of HSS cutter supported the findings mentioned above. The stated HSS treatment technology would implement nano-structure of traditional tool steel through phase change. It could be a new method to improve the performance of HSS cutter.
关键词:
high speed steel
,
null
,
null
Journal of Alloys and Compounds
A solid solution with formula (Y1-xTbx)(3)GaO6 (x = 0-0.5) was prepared by solid-state reaction method. Powder X-ray diffraction (XRD) shows that Y3GaO6 is isostructural to Gd3GaO6 (Cmc2(1)), and the lattice parameters are a = 8.8364(1) angstrom, b = 11.0899(1) angstrom and c = 5.3937(1) angstrom. Atomic parameters were derived by Rietveld refinement of the XRD pattern. Photoluminescence (PL) spectra show a strong green emission of 543 nm from the D-5(4) -> F-7(5) transition of Th3+ at room and liquid nitrogen temperature. There is a wide saturation range of the PL intensity for the Th3+ content from x = 0.04-0.20, and a long life time about 1200 mu s for the green 543 nm emission at room temperature. (c) 2006 Elsevier B.V. All rights reserved.
关键词:
Y3GaO6;crystal structure;Tb3+ doped;photoluminescence;luminescence properties;dependence;y3al5o12;phosphor;ions;ce3+;tb-3;uv
Journal of Solid State Chemistry
The crystal structures of a series of compounds with the composition Ln(3)GaO(6)(Ln = Nd, Sm, Eu, Gd, Tb, Dy, Ho and Er) synthesized by solid-state reaction at 1400degreesC are investigated. X-ray diffraction shows that Ln3GaO6 has a non-centro symmetric orthorhombic structure (space group Cmc2(1)). Lattice parameters a, b, c and cell volume and the average distances between Ln(l)-O, Ln(2)-O of these compounds decrease with the decreasing of the radii of trivalent Ln ions, which accord with the expected lanthanide contraction behavior. There are two sites of seven-fold coordination for Ln atoms with oxygens, and Ga atoms are in oxygen tetrahedra which are distorted and elongated along the a-axis. Magnetization measurements indicate that the susceptibility X changes with temperature in Curie-type manner. (C) 2004 Elsevier Inc. All rights reserved.
关键词:
Ln(3)GaO(6);crystal structure;Rietveld refinement;X-ray diffraction;garnets
Journal of Luminescence
Ln(3+) (Ln = Nd, Sm, Eu, Gd, Dy, Ho, Er)-doped Y3GaO6 compounds were prepared by solid-state reaction, and their optical spectra such as absorption, photoluminescence, excitation and time-resolved spectra have been measured for Ln Nd, Sm, Dy, Ho, Er. X-ray powder diffraction shows that the lattice parameters of the compounds (Y(0.96)Ln(0.04))(3)GaO6 decrease with the decrease of the radii of trivalent Ln(3+) ions, indicating that Ln(3+) ions have substituted for y(3+) ions in the lattice. Optical spectra show that there are obvious absorptions at ultraviolet to visible region. The strong emissions in visible and infra-red region show that Y3GaO6 is a suitable host for rare-earth-doped laser crystal and phosphor materials. (C) 2004 Elsevier B.V. All rights reserved.
关键词:
crystal-field;absorption-spectra;luminescence;y3ga5o12;glasses;garnet;y2o3;ions;laf3;tb3
Journal of Solid State Chemistry
A serial of samples in Y2O3-Ga2O3-Tm2O3 pseudo-ternary system are prepared by solid-state chemical reaction method. The range of solid solution in (Y1-xTmx)(3)GaO6 is 0 < x < 0.384. Powder X-ray diffraction shows that the compounds crystallize in Gd3GaO6 (Cmc2(1))-type structure. The solid solubilities of Y3+xGa5-xO12 (x = 0-0.77) and Tm3+xGa5-xO12 (x = 0-0.62) are 37.5-47.11 at% Y2O3, and 37.5-45.26 at% Tm2O3, respectively. PL spectra of Tm-doped Y3GaO6 show that there is a sharp blue emission at similar to 456 nm from the D-1(2) -> F-3(4) transition at room temperatures with two lifetimes (similar to 5 and similar to 15 mu s) and a narrow saturation range of PL intensity for the Tm3+ content from x = 0.005 to 0.03. The sharp emission and long lifetime of (Y1-xTmx)(3)GaO6 indicate that Y3GaO6 is a potential phosphor and laser crystal host material. (c) 2005 Elsevier Inc. All rights reserved.
关键词:
Tm3+ -doped Y3GaO6;Y2O3-Ga2O3-Tm2O3 system;(Y1-xTmx)(3)Ga5O12 solid;solution;luminescence;crystal-structure;luminescence;phosphor;cations;ions;tb3
肖剑荣
,
徐慧
,
李幼真
,
刘雄飞
,
马松山
,
简献忠
中国有色金属学报
使用CF4和CH4为源气体,利用射频等离子体增强化学气相沉积法,制备了a-C:F:H薄膜样品.采用拉曼光谱仪、傅里叶变换红外光谱仪、X射线光电子能谱仪(XPS)对薄膜的结构进行了测试和分析.研究发现:该膜呈空间网状结构,膜内碳与氟、氢的结合主要以sp3形式存在,而sp2形式的含量相对较少;在薄膜内主要含有C-Fx(x=1,2,3)、C-C、C-H2、C-H3等以及不饱和C=C化学键;同时,薄膜中C-C-F键的含量比C-C-F2键的含量要高.在不同功率下沉积的薄膜,其化学键结构明显不同.
关键词:
a-C:F:H薄膜
,
等离子体增强化学气相沉积
,
低介电常数
,
化学键
弭群
,
曹丽云
,
黄剑锋
航空材料学报
doi:10.3969/j.issn.1005-5053.2010.4.014
以磷酸为填充液与改性剂,采用微波水热法对碳/碳 (C/C)复合材料进行了抗氧化改性.主要研究了微波水热反应温度、时间对改性C/C复合材料的结构及抗氧化性能的影响.研究结果表明:浸渍磷酸后材料抗氧化性能得到明显改善,微波水热改性是提高C/C复合材料抗氧化性能的一种有效途径;复合材料的抗氧化性能在120～210℃的水热改性范围内随着温度的升高而提高;经 4h水热处理后材料的抗氧化性能达最佳;在210℃/4h微波水热处理后的C/C复合材料在700℃的空气气氛中氧化10h后的质量损失为9.47%,相对未改性的C/C复合材料抗氧化效果明显增加.
关键词:
碳/碳复合材料
,
微波水热法
,
抗氧化
,
改性
高帆
,
左萌萌
,
李彩霞
,
黄亮亮
人工晶体学报
为了丰富亚磷酸盐结构,为多孔材料的定向合成提供一定的实验数据,在溶剂热的条件下,以咪唑为结构导向剂合成了一个具有三维开放骨架结构的新型亚磷酸镓化合物Ga8(H2O)6(HPO3)14·(C3N2H6)3·H3O(化合物1),并通过粉末X-射线衍射、红外光谱、热重、ICP和CHN元素分析对化合物进行了表征.单晶X-射线衍射分析结果表明,化合物1属于三斜晶系,P-3c1空间群,晶胞参数为a=b=1.33388 (8) nm,c =1.7886(2) nm,γ=120 (4)°,Z=2.其结构是由GaO6八面体和[HPO32-]假四面体单元相互连接构成.该结构沿着[100]和[010]方向具有12元环孔道.值得注意的是,在化合物1的结构中存在两种不同的次级结构单元(SBU):经典的6*1单元Ga3P4和齿轮状的GaP6单元.
关键词:
开放骨架
,
溶剂热
,
亚磷酸镓
