模式识别在α—方石英强化日用瓷中的应用

本文采用计算机模式识别手段对a-方石英强化·日用瓷进行了数据处理,得到了多维空间向二维空间的投影方式和优化区域,且样品的显微结构分析及力性测定结果与模式识别结果相一致.     

H2Ti4O9纳米晶的制备与表征

采用机械化学法,利用离子交换反应,通过离子交换、层离和沉淀过程制备了高比表面积的H2Ti4O9纳米晶体.采用XRD、TEM、热分析、N2吸附脱附等温过程和吸收光谱对制备的H2Ti4O9纳米晶体进行了表征.结果表明,以TiO2纳米晶片形式存在的微晶Ti4O9^2-,其径向尺寸低于50nm,纳米晶片的比表面积取决于反应溶液的pH值和对前驱物K2Ti4O9球磨的时间.将K2Ti4O9球磨2h后悬浮于1mol/L HCl溶液中搅拌,进行离子交换反应,最后将溶液pH值调整至8,沉淀后所得产物H2Ti4O9的比表面积达328.4m^2·g^1.     

微波烧结锇的工艺研究及动力学分析

采用微波烧结技术制备锇（Os）烧结体,研究了生坯压制压强和微波烧结主要工艺参数（升温速率、烧结温度和保温时间）对Os烧结体组织结构和相对密度的影响规律,分析了微波烧结致密化的机理。结果表明,1350 ℃微波烧结后Os平均晶粒尺寸约0.22 μm,与粉体颗粒尺寸差别不大;随着烧结温度增加到1500 ℃,晶粒尺寸长大到0.76 μm。1500 ℃烧结时,延长保温时间,Os烧结体的相对密度先快速增加,后缓慢增加。1500 ℃微波烧结60 min后,Os烧结体相对密度为94.3%,平均粒径小于1 μm。烧结动力学分析表明,Os的致密化过程是体积扩散和晶界扩散共同作用的结果,随着烧结温度的升高,扩散机制从晶界扩散逐渐向体积扩散转变。     

Preparation and emission property of scandia pressed cathode

Scandia pressed cathodes were prepared by powder metallurgy method using mixed powder of scandia doped tungsten and barium-calcium aluminates obtained by different mixing methods.The element distribution uniformity greatly affected the emission property.The powder prepared by ball-milling had small particle size and uniform distribution of different elements.This kind of powder was favorable for the chemical reaction among Ba,Ca aluminates,scandia and tungsten to take place sufficiently to form active substance which can improve the emission property.The emission current density of the cathode prepared with ball-milling powder was about 8 times higher than that prepared by manually mixing method,4 times higher than Os coated M-type cathode.The higher content of the active substance on the cathode surface prepared by ball-milling led to the better emission performance of the cathode.     

机械化学法N掺杂纳米TiO2的制备与表征

采用机械化学法合成了N掺杂纳米TiO_2粉末,对所获得的N掺杂TiO_2粉末进行了分析与表征．实验结果表明,采用六次甲基四胺(HMT)为N源,将原料TiO_2和HMT混合物经过高能球磨处理后,合成的N掺杂TiO_2主要为锐钛矿和板钛矿的混晶相,与原料相比具有小的晶粒度和大的比表面积,对波长大于400nm的可见光具有良好的吸收性能,其吸收边红移至530nm．     

Photocatalytic Destruction of Nitrogen Monoxide over La^3＋ and N Co-doped SrTiO3 Powders under Visible Light Irradiation

Lanthanun, and nitrogen co-doped SrTi03 was prepared by a mechanochemical reaction using SrTi03, urea and la203 as the raw materials. The samples were characterized by X-ray diffraction, X-ray photoelectron spectrometer, trans-mission electron microscopy, and nitrogen adsorption-desorption isotherm measurements, lanthanum doping could increase the doping content of nitrogen in the sample. The sample prepared with 0.2 mol% La203, 22 mol% urea and 77.8 mol % SrTi03 by mechanochemical reaction, which has nearly the same nitrogen and lanthanum doping fractions, exhibited high photocatalytic activities. Under the irradiation of light with wavelength larger than 400, and 290 nm, the photocatalytic activity of nitrogen and lanthanum co-doped SrTi03 were 2.6 and 2 times greater than that of pure SrTi03.     

La2O3-Mo阴极材料热分析研究

采用热分析、X射线衍射、扫描电镜等方法对Mo-La2O3阴极中La2O3与Mo2C的反应情况进行了研究.实验结果表明:La2O3与Mo2C在高温下可以发生化学反应,产生单质La和金属Mo;反应物存在状态不同,二者发生反应的温度不同. 粉末样品中二者反应温度(1203K)低于阴极丝中二者的反应温度(1533K).     

微量Fe元素对氧化钨粉还原过程的影响

采用液–固掺杂结合两步氢还原法分别制备未添加和添加质量分数0.1％和1.0％Fe的金属W粉,研究了微量Fe元素对WO3还原过程及产物结构特征的影响.结果表明:WO3前驱体粉体经掺杂和煅烧处理后,在其颗粒表层晶格中形成了含Fe固溶体;在氢气还原过程中,Fe的固溶能够降低WO2.9→WO2和WO2→W的还原温度,促进WO3...     

La2O3对Mo粉性能影响的研究

采用光电子能谱分析方法对掺杂La2O3的Mo粉的性能进行了研究，结果表明：掺杂La(NO3)3的MoO2粉经过还原处理后，Mo粉表面的纳米La2O3微粒可以减小Mo基体的特征能量损失峰，增加Mo3d光电子谱峰强度，由于纳米LaO3粒子在金属Mo的表面及周围对Mo起到包埋效应，减小了Mo与大气的接触面积，从而使Mo的抗氧化能力增强。     

La2O3-Mo阴极材料中La2O3稳定性研究

本文采用高温光电子能谱方法对La2O3-Mo阴极及碳化La2O3-Mo阴极材料表面La2O3的化学稳定性进行了研究.实验结果表明,La2O6并不具备文献报道的极好的化学稳定性.材料中的La2O3在高温、真空条件下,其部分晶格氧发生分离.La2O3可以被Mo2C还原成单质La.单质La的结合能高于La2O3的结合能.实验证实单质La3d5/2的结合能为835.96eV,并首次给出La3d3/2的结合能实验数值为852.23eV.