MORPHOLOGY AND CRYSTALLOGRAPHY OF ALUMINIUM NITRIDE WHISKERS

The AlN whiskers were composed by the Al_2O_3-C system with some CaF_2 and NH_4Cl addition under the condition of the carbothermal reduction treatment of 1450 C and 2h as well as nitrogenous atmosphere. The composed AlN whiskers were analysed and the results show that some whiskers morphology such as plate cwoed, brached corrugated were observed and the ratios of length to diameter change greatly. The composed whiskers are not even. some surface quality is not high. TEM analyse show that the fiber axes are normal to[0112] and [1101]. The mechanism of the growth of the whiskers is supposed to be VLS(Vapor-Liquid-Solid)     

GRAIN GROWTH IN NANOSIZE AIN POWDERS

The nanosize AlN particles wereprepared by evaporation-condensation method in DCarc nitrogen plasma. Aluminium of high purity(99. 999% ) was evaporated and nitrided in nitro-gen plasma by use of high temperature and high re-activity of plasma gas. The purity of nanosize AlNparticles is more than 98% (wt%) and the averageparticle size is about 50nm. The grain growth ofnanosize AlN particle is also studied. The resultsshow that the nanosize AlN particle begins to growup at 900℃ and the grain growth increase rapidlyat 1100℃. When the temperature is increased to1600℃, the surface of nanosize AlN particle hasbeen sintered softly. Results will be beneficial to prepare AlN ceramics.     

燃烧合成-维纳米结构AIN及其生长机理研究

以铝粉（A1）和NH4F为主要原料,Nb为添加剂,在N2压力小于0．5MPa的条件下采用高温自蔓延燃烧法（SHS）合成了一维纳米结构的AlN粉体,并通过差热分析（TG／DSC）分析了Al—N2体系的热力学机理,运用X-射线衍射仪、场发射扫描电子显微镜（SEM）分析了所合成一维纳米结构AlN的物相组成和显微结构．结果表明,当Al：NH4F为4：1（wt％）时,在添加剂Nb的作用下,合成的产物主要为一维纳米结构六方长针状AlN,该粉体纯度高、晶体结构完整,且沿（100）存在明显择优取向;所合成的一维纳米结构AlN的生长机理属于SLS生长机理．     

RESEARCH ON PREPARATION OF ULTRAFINE ALN POWDERS

The high purity of ultrafine power(UFP)of a-luminium nitride(AlN) are prepared by the reaction of nitrogenplasma with metal aluminium in D.C.plasma reactr.Both thenitriding principle and the AlN nucleation mechanism are stud-ied.The rusults,indicate that the chemical reaction in the forma-tion process of AlN UFP is very complicated and the nitridingreaction is corelated to the concentration of reactants and thetemperature.The particle size cav be adjusted by controlling thepartial pressure of the reactants,the temperature and the react-ing rate.     

THE GROWTH MECHANISM OF Al_2O_3/Al COMPOS-ITES BY DIRECTED OXIDATION OF MOLTEN METALS

The process of the directed oxidiation of al-loy Al-1%Mg-7%Si was invertigated by X-Ray diffraction(XRD),optical microscopy,scanning electron microscopy(SEM)and energy dispersive spectrometer(EDS),which in-cluded evolution of the surface of the melt in the incubationperiod,nucleation of Al_2O_3/metal composite and microstruc-ture of Lanxide material its growth front.Some new resultsabout the mechanism of the for mation of Al_2O_3 are involved.     

STUDY ON HEAT-TREATMENT OF AIN/SiCw COMPOSITES AND EFFECTS ON MICROSTRU-CTURE AND PROPERTIES

AlN-SiC whisker composites with Y_2O_3 and SiO_2 additives were heat-treated at 1300 C in air. The phase crmposition and microstructure were analyzed using XRD, SEM and HREM techniques to study the effect of heat-treatment on the microstructure and properties of the composites. The results reveal that the mechanical properties and high temperature oxidation resistance of the composite of which additives composition approaches the eutectic poi of Y_2O_3-SiO_2 can be improved through the heat-treatment. Glass phase in the grain boundary is observed to react with the surface composition of AlN forming fibrous 2H~8 Sialon, resulting a crossing structure produced by fibrous 2H~8 Sialon and SiC whiskers.     

Structural and optical characteristics of Al_xGa_(1-x)N/AlN superlattice

AlN/Al0.3Ga0.7N superlattices were grown on (0001) sapphire substrate by metal-organic chemical vapor deposition (MOCVD). The superlattice period varies from 6 to 30. The layer thickness of different period stack was designed. GaN or AlGaN template was employed for growing AlN/AlGaN superlattices. Reflectivity, SEM, AFM and XRD data of the AlxGa1-xN/AlN superlattices are presented. It is found that the templates used have an intensive impact on surface roughness and interfacial properties of following AlN/AlGaN superlattices. The result of atomic force microscopy indicates that AlN/AlGaN superlattices grown on GaN template exhibit quasi-two-dimensional growth mode. The resulting superlattice has a smooth surface morphology and distinct interface. No crack is observed in the area of a 2-inch wafer.     

用超临界二氧化碳法合成偶氮苯-环糊精纳米复合体

以超临界二氧化碳为溶媒，将偶氧苯分子插入到α-以及β-环糊精的分子环空洞中合成出了偶氧苯-环糊精纳米复合体。环糊精与偶氧苯的摩尔分子为1：1的混合物，放入压力30MPa、温度120℃的超临界装置中处理后，对其生成物采用红外、固体核磁共振、X-射线衍射、差热分析及化学元素分析等手段进行了分析，结果表明偶氧苯成功地插入到β-环糊精分子环空洞中形成了纳米复合体，而α-环式糊精与偶氮苯之间只是简单的物理混合物，没有形成纳米复合体。所得到的偶氮苯-β-环式糊精复合体具有通道式分子结构：二个β-环式糊精分子捕获一个偶氧苯分子，β-环式糊精的分子环空洞连成一个通道。偶氧苯插入到β-环式糊粉分子环空洞中后其热稳定性也得到大幅度提高。     

绞龙一次成型模式及机理的研究

利用锥状面正螺旋面的形成原理和导流成型原理，研究螺旋绞龙叶片一次绕制成型模式的工艺和装置。从而提高绞龙叶片的制作质量和材料的利用率，提高了生产效率。     

SiO2氧化层在DIMOX法制备SiCp/Al2O3-Al复合材料中的作用机制

利用直接金属氧化法制备了SiC颗粒增强Al2O3-Al基复合材料，借助于XRD、光学金相显微镜（OM）和扫描电镜（SEM）对该复合材料的微观结构进行了观测，分析了SiO2氧化层的形成在复合材料制备过程中的作用。结果表明，SiO2层可以防止材料粉化现象的发生。缩短反应的孕育期，并可避免材料的胞状生长，促进材料的致密化。     

直接金属氧化法制备SiCp/Al2 O3-Al复合材料的微观结构与工艺性能的研究

采用直接金属氧化法制备了SiC颗粒增强Al2O3-Al基复合材料。借助XRD和光学金相显微镜对该复合材料的组成及微观结构进行了观察，分析了SiO2层、合金成分和温度制度对复合材料性能的影响。结果表明该复合材料结构致密且渗透完全，微观结构由3种相互穿插相组成，即SiC预制体、连续的Al2O3基体及呈网状结构分布的未被氧化的残余Al。     

提高信噪比的有效方法——饱和放大法

本文针对如何提高视频信号处理电路的信噪比（Ｖｓ／ＶＮ）做了有益的探讨，并就饱和放大法充分利用三极管工作于饱和区时非线性放大的特点，对处于不同电平的图像信号和背景噪音同时分别实现放大与衰减处理的工作原理做了分析说明。     

SEPARATION OF METAL IONS AS CHELATES OF 1N2,7O3,6S IN THE PRESENCE OR ABSSENCE OF TBA+ BY CAPILLARY ELECTROPHORESIS

Separation and determination of metal ions based on the formation of chelate anions with 1-Ni-troso-2, 7-dihydrexynaphthalene-3, 6-disulfonic acid (1N2, 7O3, 6S) was studied by using HPCE of the nine metal ions examined, the ions that can be detected sensitively -with 1-Nitroso-2, 7-dihydrexynaphthalene-3, 6-disul-fonic acid were Fe2 , Co2 .Cu2 . Ni2 ,Zn2 and Pd2 , The cobalt chelate could exist in two oxidation states of     

Si／C／N纳米粉原位生长SiC晶须

Ｓｉ／Ｃ／Ｎ纳米粉原位生长ＳｉＣ晶须＊潘正伟①张立同②ＳｉＣ晶须的良好热性能和化学稳定性，特别是接近于单晶的理论强度十分引人注目。目前，制备ＳｉＣ晶须的主要方法有ＳｉＯ２碳热还原法和稻壳法［１］。在这两种方法中，均需要加入催化剂（如Ｆｅ、Ｃｏ等）以形...     

30t/d米糠膨化浸出制油工艺中间试验

通过米糠膨化浸出制油中间试验,建立了３０ｔ／ｄ米糠膨化浸出制油生产线;稳定了米糠贮存性,提高了米糠制油的得率;毛油出油率平均为１７５％,出油效率为９５％～９７％,出粕率为８５％～８７％,溶剂损耗平均为４５ｋｇ／ｔ,粕残油平均为１３％左右     

金红石和锐钛矿型二氧化钛薄膜的制备和特性评价

综述了作者近年来通过交流螺旋磁控溅射制备锐钛矿和金红石型微晶薄膜的研究进展，阐述了薄膜的制备工艺与其晶体结构、组成、光学性能以及杀菌能力的关系，并通过有效的方法对其光学性能进行了改进。     

声化学制备工艺对PAM/La2O3有机-无机杂化材料性能的影响

采用声化学方法制备了PAM／La2O3有机-无机杂化材料，研究了单体-稀土比例、不同引发剂量、不同反应时间及不同反应温度对材料的光学性能的影响规律。结果表明：所制备的杂化材料对200-250nm范围内的紫外光具有选择吸收的特性，随杂化材料中La2O3含量的增加以及引发剂含量的提高、反应时间的延长和反应温度的提高，材料对低波段紫外光的选择性吸收趋势越明显。     

晶包隔红高温慢烧釉稳定机构的研究

通过对Cd(SxSe1-x)大红色料的SEM、XRD分析，探讨了色料颗粒的不同晶包装态和组成同稳定性的关系，在对多组分基础釉进行实验的基础上获得适用于ZrSiO4-Cd(SxSe1-x)大红色料的稳定基釉配方，通过XRF和SEM观察对其高温慢烧中的稳定机制进行了分析研究。