Effects of hydrogen on the transition layers between diamond films and Zr, Hf substrates

Highly purified polycrystalline wafers of Zr and Hf were chosen as substrates for diamond deposition by means of the d.c. arc discharge plasma CVD method. Polycrystalline diamond films were formed on both substrates. Scanning electron microscopy and high resolution X-ray diffraction were used to investigate the surface morphology of the diamond films and the composition of the interface layers between the diamond films and substrates. The experiments showed that the transition layer between the diamond films and Zr substrates was ZrC, ZrH and ZrC_0.32H_1.2. For Hf substrates, in addition to HfC, it is supposed that there were also some hydrides or carbohydrides in the transition layer, because several X-ray reflections appeared which could not be assigned to Hf, HfC or diamond.     

Preparation of Titanium Nitride/Alumina Laminate Composites

A preparation route for TiN/Al₂O₃ laminate composites has been described. A water-based process using Al₂O₃ and TiN slurries with solids contents of 40 and 35 vol%, respectively, was used to make TiN and Al₂O₃ tapes. The removal of the binder was monitored by weight-loss measurements in a thermogravimetry unit. Bodies composed of Al₂O₃ and TiN tapes were densified at temperatures of 1400° and 1500°C using the Spark Plasma Sintering^® (SPS) technique. Densities of >98% of the theoretical densities were approached. Crack-free and almost fully densified TiN/Al₂O₃ compacts were prepared by heating the burned-out green bodies to the final sintering temperature (1500°C) at a rate of 100°C/min, and with a holding time of 5–10 min, under a pressure of 75 MPa. The microstructures of the obtained compacts were studied using scanning electron microscopy. Grain sizes in the sintered Al₂O₃ and TiN compacts were similar to those of the precursor powders. Hardness and indentation fracture toughness were measured at room temperature, and the monolithic compacts as well as the laminate composites exhibited anisotropic mechanical behavior; i.e., the cracks propagated much more easily in a direction parallel to the laminas than perpendicular to them.     

新农村建设规划过程中的问题与对策探析——以都昌县新农村建设为例

建设社会主义新农村,要坚持规划先行,在当前新农村建设的过程中,合理地进行村庄建设规划具有重要的意义。本文就都昌县目前农村建设的现状及新农村建设规划过程中出现的相关问题进行探析,并对都昌县新农村建设提出了可行性的对策。     

纳米管合成研究进展

当今纳米科学技术飞速发展，其中纳米管已构成了纳米材料的一个非常重要的类别。本文介绍近几年来由化学键结合的纳米管以及由分子间力形成的一些纳米或具有中观尺度的管状结构材料的合成研究进展。     

Size and pressure effects on solid transition temperatures of ZrO2

Transition temperatures between tetragonal and monoclinic polymorphs of ZrO₂ nanoparticles, thin films and nanostructured materials are calculated by considering energetic contributions of surface (interface) energy and surface stress on total Gibbs free energy. The transition temperatures drop as the size of the nanocrystals decreases, which is consistent with available results.     

Rh(Ⅲ)—钍试剂—高碘酸钾新体系催化光度法测定痕量铑

在pH3.9醋酸盐缓冲溶液中及加热条件下,Rh(Ⅲ)对高碘酸钾氧化钍试剂这一褪色反应有强烈的催化作用,可藉自来水冷却中止反应,研究了催化光度测定痕量铑的影响因素,建立了一个检出限和测定范围分别为0.06ng/ml和0.12～4.5ng/ml铑的催化光度新方法。     

Redundancy filtering and fusion verification for video copy detection

Multimedia Systems - Recently, the frame fusion based video copy detection scheme provides a possibility to detect copies in a continuous query video stream. However, its computational complexity...