电流密度对铝合金微弧氧化膜物理化学特性的影响

利用微弧氧化(MAO)技术，在LYl2铝合金上沉积了显微硬度达42.14GPa的超硬陶瓷膜.采用x射线衍射仪和显微硬度计研究了阳极电流密度j_a和阴极、阳极电流密度比j_c/j_a对MAO膜相构成和力学特性的影响.此外，利用扫描电子显微镜和恒电位仪分别对膜的微结构和抗点腐蚀特性进行了分析.结果表明，高j_a制备的膜主要含α-Al₂O₃相，低j_a制备的膜主要含γ-Al₂O₃相.显微硬度测试表明，这类膜有较高的硬度，但以j_a=15A/dm²和j_c/j_a=0.7制备的陶瓷膜硬度最高.抗点腐蚀测试表明，j_c/j_a对陶瓷膜的微结构有很强的影响. 关键词： 微弧氧化 显微硬度 电流密度 抗点腐蚀     

N离子注入对金刚石膜场发射特性的影响

不同剂量的N离子被注入到化学气相沉积金刚石膜内，研究了表面结构及场发射特性的变化.Raman谱和x射线光电子能谱分析表明，N离子的注入破坏了金刚石膜表面原有的sp3结构，并在膜内形成大量的sp2 C—C 和sp2 C—N 键.样品的场发射测试显示N离子的注入显著提高了金刚石膜场发射特性，膜的场发射阈值电场从注入前的18 V/μm下降到注入后的4 V/μm.金刚石膜场发射特性的提高归因于N离子注入后膜内sp2 C键含量的增加和体内缺陷带的形成，这些变化能改变膜的表面功函数，提高Feimi能级，降低电子隧穿表面的能量势垒. 关键词： 场致电子发射 N离子注入 金刚石膜 热丝化学气相沉积     

Characterization of Microarc Oxidation Process on Aluminium Alloy

The specific features of electric current variation against time were studied by keeping the anode and cathode pulse voltage to be constant. The maximum thickness of the films fabricated by microarc oxidation was found to be closely related to the voltage. The surface morphology of the coatings can be divided into different stages according to the variation of electric current. A method for obtaining high micro hardness coating has been discussed.     

用表面生长CVD金刚石的石墨合成高压金刚石

 用热灯丝CVD方法在多晶石墨衬底表面制备CVD金刚石颗粒，并用这种石墨在高温高压条件下采用六面顶压机合成出高压金刚石。初步实验结果表明：采用其表面生长CVD金刚石颗粒的石墨合成高压金刚石，可以提高金刚石的转化率和降低合成压力。     

Synthesizing of ZnO Micro/Nanostructures at Low Temperature with New Reducing Agents

Instead of the conventional graphite, new additional reducing agents （diamond, silicon, metal elements, etc.） have been mixed with zinc oxide （ZnO） powder to fabricate ZnO micro/nanostructures by a thermal vapour transport method. Due to the strong reducibility for those additions, the corresponding heating temperature is decreased by 100 500℃ compared to the case of graphite, which subsequently decreases the corresponding growth temperature for the products. Being placed separately for the powder sources of ZnO and addition, a vapour-vapour reduction-oxidation reaction mechanism between the sources is proposed as an important channel to fabricate ZnO. Photoluminescence and magnetic examinations indicate that the ZnO products synthesized have strong ultraviolet （visible） emissions and are room-temperature ferromagnetic, meaning that the products are available for applications.     

Effect of CO2 Addition on Preparation of Diamond Films by Direct-Current Hot-Cathode Plasma Chemical Vapor Deposition Method

Diamond films are deposited on Mo substrates by dc hot-cathode plasma chemical vapor deposition method using a CH4-H2-CO2 gas mixture. Adjusting the flow of CO2, we study the relevant influence on surface morphology, grain orientation and crystalline quality of films with scanning electron microscopy, x-ray diffraction, Raman spectroscopy, respectively. The results show that grain orientation of the films has a transition with the increasing CO2 addition, from （100） orientation to （110） orientation and then （111） orientation. The crystalline quality is improved but the growth rate is decreased by raising the flow of CO2. The experimental results are also discussed briefly.     

高导热金刚石薄膜的研究

分析了影响金刚石膜热导率的主要因素，指出声子的散射是造成金刚石膜热导率降低的主要原因．采用光热偏转法实现了金刚石薄膜热导率的测试，测量误差小于5%，从减少杂质和晶界对导热声子的散射入手，研究了在不同的制备方法下碳源气体和金刚石膜内晶粒取向对其热导率的影响．结果表明在低碳源气体浓度下采用微波等离子体化学汽相沉积方法制备的具有较高程度（400）晶粒取向的金刚石薄膜具有高的热导率性质．优化的工艺条件制备出热导率为15.2W/（K·cm）左右的金刚石膜． 关键词：     

甲醇在热阴极DC-PCVD方法制备金刚石膜过程中的作用

采用热阴极DC－PCVD方法制备了金刚石膜，研究了甲醇对放电状态和金刚石膜生长特性的影响。结果表明，通入适量的甲醇有利于稳定辉光放电状态，保持阴性清洁，提高膜的生长质量。用扫描电镜和拉曼光谱等测试手段对金刚石膜的生长特性进行了分析。     

铝合金微弧氧化过程中电学参量的特性研究

利用自制的数据采集系统研究了恒定电压下铝合金微弧氧化过程中有关电学参量随时间的变化规律.结果表明：通电回路中的阴极和阳极峰值电流随处理时间的变化明显分为5个阶段；陶瓷膜的动态正向电阻和电阻率随处理时间分阶段变化，而动态的反向电阻和电阻率随时间的变化不大.在微弧氧化过程中，各时刻的动态正、反向电阻值不同，一般情况下，动态正向电阻远大于反向电阻.对不同处理时间样品的扫描电子显微镜分析表明，陶瓷膜呈多孔结构并随处理时间分阶段变化. 关键词： 铝合金 微弧氧化 电学参量 陶瓷膜