钛酸钡中的硼间隙及其对PTCR效应的影响

通过B2O3蒸汽掺杂，钛酸钡晶胞膨胀，表明硼离子可以进入钛酸钡晶格中形成硼间隙。B2O3蒸汽掺杂使含Y钛酸钡陶瓷室温电阻率下降，升阻比提高。同样的烧结条件下，钛酸钡陶瓷的PTCR效应随B2O3蒸汽掺杂源的浓度升高而升高。硼间隙和／或相关缺陷络合物可以形成电子捕获中心，从而提高PTCR效应。     

碳纳米管-银复合材料的制备工艺和电导率

采用粉末冶金方法制备碳纳米管-银复合材料,研究了制备工艺、碳纳米管含量对碳纳米管-银基复合材料密度、硬度、抗弯强度、电导率的影响.结果表明:采用复压烧结,烧结温度为700℃时,复合材料的性能较好;碳纳米管和银的弱界面结合,使得碳纳米管对复合材料的强化效果不明显;当碳纳米管的体积含量大于10%时,碳纳米管在晶界上发生偏聚,碳纳米管-银界面对电子产生散射,导致复合材料的电阻率迅速增加.     

氧化硼除铁净化镁合金的研究

在镁合金熔剂JDMR中加入氧化硼净化镁合金液,使铁含量降低到0.002%左右.氧化硼最佳用量为0.61%,最佳处理温度735℃,最佳处理时间40min.处理后的镁合金腐蚀速率从15.1mg/(cm2·day)降低到0.4mg/(cm2·day).X衍射证明FeB的形成是氧化硼除铁的主要原因.最后从热力学和动力学角度分析了氧化硼除铁机制.     

MgO-B_2O_3-SiO_2渣晶化动力学

应用差热分析（ＤＴＡ）技术研究了Ｃｒ２Ｏ３、Ｌａ２Ｏ３、ＣｅＯ２、Ｖ２Ｏ５、Ｓｉ３Ｎ４、ＳｉＣ、ＣａＦ２、ＭＯｘ对ＭｇＯＢ２Ｏ３ＳｉＯ２渣中含硼组分析晶活化能的影响。结果表明,Ｃｒ２Ｏ３、ＣｅＯ２、ＣａＦ２、ＳｉＣ、ＭＯｘ作为晶核剂加入后,可降低析晶活化能,有利于含硼组分以结晶相析出,是有效的晶核剂;Ｌａ２Ｏ３和Ｖ２Ｏ５对析晶活化能没有影响;Ｓｉ３Ｎ４则增强玻璃网络稳定性,提高析晶活化能。所以Ｌａ２Ｏ３、Ｖ２Ｏ５和Ｓｉ３Ｎ４作为晶核剂是无效的。     

Room-temperature growth of high-purity titanium nitride by laser ablation of titanium in a nitrogen atmosphere

Thin films of titanium nitride (TiN) were deposited on glass substrates by KrF excimer laser ablation of titanium over a very broad nitrogen pressure range with different target–substrate distances at room temperature. The as-deposited TiN thin films were analyzed by X-ray diffraction and transmission electron microscopy. It was found that the as-deposited thin films are normally a mixture of TiN and metallic titanium, and the TiN-to-Ti ratio of the as-deposited thin film depends on both the nitrogen pressure and the target–substrate distance. High-purity TiN thin films can be obtained only in a very narrow deposition parameter range. A compound parameter (the product of the nitrogen pressure and the target–substrate distance) is proposed to optimize the deposition of high-purity TiN thin films, and the possible mechanism is also discussed. It was also revealed that the as-deposited TiN thin films are polycrystalline with an average grain size of about 20 nm.     

Enhancement of the properties of pulsed laser-deposited carbon nitride by the synchronisation of laser and N2 gas jet pulses

In surface coatings technology, especially in carbon-based materials, the deposition of energetic species is acknowledged as one of the most important factors in producing hard coatings. Pulsed laser deposition (PLD) of carbon under vacuum creates such energetic species and so carbon films with very high hardness values have been reported. However, when PLD takes place in a gas ambient, the ablated carbon species are decelerated to an extent that depends on the background pressure. As a result, during CN_x deposition, although the carbon species react effectively with N₂ at the beginning of their trajectories, when they reach the substrate they usually do not have sufficient kinetic energy to form a hard coating. In this paper we describe a new technique that combines the intense environment of an expanding N₂ jet with low-pressure PLD to produce CN_x species that travel almost free of collisions and reach the substrate with high kinetic energies. This new configuration is based on the synchronised pulsing of a N₂ jet with the laser pulse. The CN films produced are shown to have an increased film hardness without suppressing the nitrogen content. Furthermore, electron energy-loss spectroscopy shows the layers to have a very high proportion of π bonding, which can be correlated to the existence of sp-hybridised carbon in the form of –CN bonds.     

Structure and electrical resistivity of the Al-carbon nanotube composites

In this paper the microstructure and the electrical resistivity of the hot-pressed Al-carbon nanotube composites have been measured. The results show that there is A1C or A1C₂ phases in the structure, the electrical resistivity of the samples with carbon nanotubes at room temperature is slightly higher than that of the samples without carbon nanotubes. There is an abrupt drop of the electrical resistivity of the Al-carbon nanotube composites at about 80 K, which is similar to the superconducting transition.     

诸因素对制备氮化铁磁性液体的影响

探讨了Ｆｅ（ＣＯ）５热分解温度,ＮＨ３流量及表面活性剂对制备氮化铁磁性液体的影响,结果表明,将Ｆｅ（ＣＯ）５热分解温度控制在１８０－２１０℃,并通入过量的ＮＨ３及采用与纳米级氮化２铁磁性颗粒和载液相匹配的表面活性和可以制备出性能较好的氮化的磁性液体。     

铝型材的钛金表面处理技术

铝型材钛金表面处理是采用真空多弧等离子体镀膜技术,在铝合金型材或其他铝产品表面形成一层与铝基体结合极为牢固的金黄色的或其他颜色的ＴｉＮ膜层。这种膜层色泽艳丽,耐候性与抗蚀性强,超耐磨,干润滑性、热韧性好,热硬性高,铝材镀钛金是在特定的真空、温度、压强、电磁场条件下进行,工艺复杂,需采用专门的设备,对操作人员素质要求较高。     

MECHANISM OF NON-EQUILIBRIUM SEGREGATION OF SOLUTE TO GRAIN BOUNDARIES

本文以空位-溶质原子拖曳机制为基础,并考虑了空位、溶质原子和复合体三者的反应平衡及晶界平衡偏聚的作用,得到了溶质原子的非平衡晶界偏聚动力学方程。对硼在奥氏体中等温及连续冷却时所产生的非平衡晶界偏聚现象进行了理论计算,得到了与实验较为一致的结果。