材料期刊网

Effect of Sintering Temperature on Microwave Absorbing Behaviour of Mn-Zn Ferrite

Yongxue GAN Pei YI Changqi CHEN (C.Q.Chen) Dept.of Mater.Sci.Eng. , Beijing University of Aeronautics and Astronautics , Beijing 100083 , China

材料科学技术（英文）

The microwave absorbing behaviour of Mn-Zn ferrite sintered at 1100,1200,1300,1400 and 1500℃ has been investigated.The phase constitution of the ferrite was analyzed by X-ray diffraction.The results show that the ferrite sintered at 1 500℃ has better microwave absorbing prop- erty than those prepared at other temperatures,due to the increase of turbulent loss generated by the formation of excessive Fe~(2+) in deoxidizing of Fe_2O_3 at high temperatures.

关键词: Mn-Zn ferrite , null , null

Chen系统的状态变量周期性反馈控制

李开明 , 李亚洲 , 冯维贵 , 林长

量子电子学报 doi:10.3969/j.issn.1007-5461.2007.05.014

采用非线性反馈控制,用附加了带参数的正弦项对Chen系统进行了有效的控制.随着参数k的逐渐增大,系统的动力学行为呈现出一系列的变化.数值研究结果表明:随控制参数的增大,驱动信号的强度渐大,混沌系统由混沌运动到周期轨道,最终到一相点.

关键词: 混沌 , Chen系统 , 不动点 , Lyapunov指数 , 反馈控制

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

0℃时YI3-C6H12N4·HI-H2O的相图及YI3·C6H12N4·HI·14H2O的合成与表征

王丽 , 吴希文 , 张晨鼎 , 张通 , 简丽 , 武朝军 , 周涛

稀土 doi:10.3969/j.issn.1004-0277.1999.02.003

采用湿渣法研究了0℃时碘化钇(YI3)-乌洛托品氢碘酸盐(C6H12N4.HI)-水(H2O)的三元体系相平衡,绘制了该体系的等温溶解度相图,相图分析结果表明,该体系中有组成为YI3.C6H12N4.HI.14H2O的配合物生成,对所得配合物进行了化学分析、X-射线粉末衍射、红外光谱、差热-热重分析,测定了其密度、晶体轴性,确定了配合物结构中的配位关系.

关键词: 相平衡 , 碘化钇 , 乌洛托品氢碘酸盐 , 配合物

C and Si ion implantation and the origins of yellow luminescence in GaN

Applied Physics a-Materials Science & Processing

We have studied the influence of C and Si ion implantation with different implantation doses on yellow luminescence (YL) from GaN. Three kinds of GaN samples were used. In their as-grown states, #1 samples had strong YL, #2 samples had no YL, while #3 samples had weak YL. Our experimental results show that: (i) after annealing at 950 degreesC, the YL intensity for Si ion implanted #1 sample decreased with increasing implantation dose, while that for C ion implanted #1 sample exhibited a reverse rule; (ii) for #2 samples, C ion implantation produced much stronger YL than Si ion implantation did after annealing at 950 degreesC; (iii) the YL intensity sequence for Si ion implanted and 950 degreesC annealed #1, #2, and #3 samples was consistent with that for the unimplanted #1, #2, and #3 samples. However, the YL intensity sequence for the C ion implanted and 950 degreesC annealed #1, #2, and #3 samples reversed with that for the unimplanted ones. In order to explain all these phenomena, we suggested a physical model which claims that the deep C center is another important origin of YL in GaN, and during C ion implantation, the C ion prefers to combine with a V-Ga to form a C-Ga.

关键词: detected magnetic-resonance;vapor-phase epitaxy;undoped gan;photoluminescence;vacancies;nitrides

SIF expressions for center cracked strip loaded by uniformly distributed stress acting on central portion of crack - Corrections of Chen's results - Response

International Journal of Fracture

关键词:

GaN/C60多层膜结构及光学特性的理论分析

韩培德 , 贾虎生 , 梁建 , 鲍慧强 , 王丽萍 , 迟美 , 许并社

材料热处理学报 doi:10.3969/j.issn.1009-6264.2005.03.024

使用转移矩阵方法计算了GaN/C60多层膜一维光子晶体的带隙结构.计算结果表明,由厚度分别为21nm、49nm的GaN、C60薄膜组成的多层膜结构,在中心带隙为6.46eV处有一不完全的光子带隙存在,反射率最高可达64.3%.

关键词: 富勒烯 , GaN , 多层膜 , 光子晶体

Q相-C2S-C4AF-C12A7系列水泥形成的研究

姜奉华 , 徐德龙

硅酸盐通报 doi:10.3969/j.issn.1001-1625.2004.06.006

通过研究Q相与C2S和Q相与C4AF的共存条件,构造Q相-C2S-C4AF水泥系统,对此系统水泥形成条件进行研究.研究表明:Q相与C2S和Q相与C4AF能够共存,可以组成Q相-C2S-C4AF-C12A7水泥系统.在Q相-C2S-C4AF-C12A7水泥系统中,Q相在1270℃开始生成,随着温度的升高,Q相的生成量逐渐增大;采用V2O5对β-C2S具有较好的稳定作用.随着C4AF量的增加,Q相的量也在增加,同时,烧成温度降低.

关键词: Q相 , Q相-C2S-C4AF水泥 , 形成条件 , 抗压强度

Q460C热处理挽救工艺

刘军刚

物理测试

Q460C钢板由于冶炼和轧制工艺不稳定,经常出现伸长率不合格的问题.论述了不同的热处理工艺对Q460C性能的影响.研究表明:Q460C经过正火后,强度明显降低.经过正火控冷后,强度、韧性均满足生产要求,提高了产品合格率.

关键词: Q460C , 热处理 , 力学性能

PEI复合润滑膜的制备与摩擦性能

廖晨棵 , 赵文轸 , 张春婉 , 李磊

复合材料学报 doi:10.3321/j.issn:1000-3851.2008.03.006

用不同溶剂通过两步法制备MoS2填充芳香和半脂肪聚醚酰亚胺(PEI)复合膜,采用乙酸酐和三氟乙酸酐(TFAA)封端.利用IR Prestige-21红外光谱仪表征纯PEI亚胺化程度;采用SDT Q600测试纯PEI的热转变与热稳定性能;用M-200型环块摩擦试验机考察干摩条件下分子柔顺性、封端剂、填料比例对PEI润滑膜摩擦因数一时间(μ-t)曲线的影响,以及载荷、填料比例对稳定服役阶段μ平均值(μ)的影响;采用扫描电镜观察磨损表面形貌,分析磨损机制.结果表明,半脂肪族PEI分子设计在不明显降低热稳定性能的前提下,显著降低了聚合物的Tg.PEI润滑膜的μ值随着摩擦时间的增加先上升后下降,但波动时间较短,μ随后逐渐升高直至润滑失效.柔性结构、三氟乙酸酐封端和适当的填料比有利于改善摩擦性能,填充70 wt%MoS2的氟化酸酐封端PEI-2具有最低为0.027的(μ)值.PEI润滑膜的(μ)值还与载荷、MoS2填料比有关.

关键词: 聚醚酰亚胺 , 脂肪族PI , 摩擦磨损 , 润滑膜 , MoS2