Fabrication of Titanium Carbide-Alumina Composites by Combustion Synthesis and Subsequent Dynamic Consolidation

Dispersed-phase composites of TiC-Al₂O₃ were fabricated from low-cost reactants by external ignition of powder compacts followed by dynamic consolidation of the hot products using explosives. Near full densification was achieved using shock pressures as low as 1 GPa. Care must be taken to allow for the escape of evoled gases during exothermic reaction, and rapid cooling of the consolidated composite must be avoided to prevent cracking.     

Nitridation of the Sol–Gel-Derived Titanium Oxide Films by Heating in Ammonia Gas

Dip-coated sol–gel-derived TiO₂ films on an alumina substrate were converted to nonstoichiometric titanium nitride (TiN _x ( x ≦ 1)) films by heating at approxmately 1000°C in NH₃ gas. TiO₂ films made from TiO₂ sols prepared from Ti(O– i -C₃H₇)₄ and stabilized by diethanolamine were more easily nitrided than those from sols containing HCl as a deflocculant reagent. This appears to be a result of the more porous structure of the former films.     

金属氧化物半导体气敏传感器的研究和开发进展

综述了近期国内外金属氧化物半导体气敏传感器的研究和开发进展；阐述了半导体气敏材料的气敏作用及机理；展望了今后半导体气敏传感器技术的发展趋向。     

金属钛生产工艺研究进展

介绍了制备金属钛的传统方法：Kroll法、Hunter法及熔盐电解法的工艺原理和概况,同时介绍了在这些方法的基础上正在开发和改进的钛制备方法,包括导电体介入还原法、连续生产钛粉的Armstrong法和直接电化学还原TiO2的FFC剑桥工艺,分析了各种方法的机理及特点. 由此指出降低钛生产成本的新工艺发展方向是转变现有间歇的海绵钛生产工艺为连续的金属钛粉及其合金的生产工艺.     

Phase Formation and Microstructure of Titanium Oxides and Composites Produced by Thermal Plasma Oxidation of Titanium Carbide

The phase formation and microstructure of titanium oxides and composites produced by Ar–O₂ thermal plasma oxidation of titanium carbide powders were investigated in detail by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Relationships between the phase compositions and microstructures of the oxides were established by combined structural and phase analyses, in correlation with synthesis conditions and phase formation mechanisms. It is revealed that vapor condensation favored the formation of anatase, which existed as smaller particles, while liquid/solid oxidation favored the formation of rutile, which appeared as larger particles or composites. A higher oxygen input in the plasma gases (Ar + O₂) enhanced the formation of anatase due to impeded oxidation and evaporation. A small amount of Ti₄O₇ and Ti₃O₅ was detected in the larger particles coexisting with rutile or TiC. These suboxides were formed as intermediates in solid oxidation of TiC or precipitated from the Ti–C–O melt during cooling. Furthermore, extensive cracks, dislocations and stresses were observed in the monolithic rutile and composites, in association with the rapid quenching in this high-temperature in-flight oxidation process.     

TiNi合金表面原位热氧化膜的结构与光电性能的研究

采用AFM、XRD和EDS等手段，对TiNi合金在空气中、400—800℃下形成的氧化膜组织结构进行了分析，并对TiNi合金表面原位热氧化膜的光电性能进行了研究．结果表明，TiNi合金在空气中氧化原位形成的氧化膜的结构主要为金红石型二氧化钛，不同温度下生长的氧化膜存在择优取向；随着氧化温度的升高，所制备的TiO2／TiNi电极的稳态光电流和开路光电压随氧化温度的升高先增大后减小，在700℃所制备的Ti02／TiNi电极的稳态光电流最大．     

Direct-Write Fabrication of Zinc Oxide Varistors

Zinc oxide (ZnO)-based pastes with tailored rheological properties have been developed for direct-write fabrication of thick-film varistor elements in highly integrated, multifunctional electroceramic devices. Such pastes exhibited pseudoplastic behavior with a low shear apparent viscosity of roughly 1 × 10⁴ Pa·s. Upon aging, the pastes attained printable, steady-state viscosities of approximately 3 × 10² Pa·s at 10 s⁻¹. Square and rectangular elements were patterned on dense alumina substrates and sintered at varying temperatures between 800° and 1250°C. Varistor elements fired at 900°C exhibited nonlinearity coefficients (α= 30) that were equivalent to high-density (>95%) varistors formed by cold isostatic pressing at 100 MPa (15 ksi) of a similar chemically derived powder heat-treated under analogous conditions.     

Fabrication of Titanium Carbide Ceramics by High-Pressure Self-Combustion Sintering of Titanium Powder and Carbon Fiber

Titanium carbide ceramics have been fabricated from the reactants titanium powder and carbon fiber by the highpressure self-combustion sintering method (HPCS) under two pressure conditions (65 MPa and 3 GPa). Porous TiC with a density of about 50% of theoretical was obtained under a pressure of 65 MPa. A possible model accounting for the formation mechanism of TiC is proposed on the basis of observation of the microstructure of the products formed from the incomplete reaction. On the other hand, dense TiC (>95% of theoretical) was fabricated under 3 GPa. The mean grain size varied, depending on the mixing molar ratio of the reactants. The influence of differences in the carbon (powder and fiber forms) on the structure of TiC compacts is discussed.     

Oxidation Resistance of Alumina–Titanium Nitride and Alumina–Titanium Carbide Composites

The presence of TiC or TiN paritcles in an Al₂O₃ matrix affects the thermal stability of the composites in oxidizing environments. In isothermic oxidation tests at 700°, 800°, 900°, 1000°, and 1100°C for up to 20 h, two different oxidation regimes have been observed at T < 900°C and at 900°C ≤ T ≤ 1100°C. At low temperatures ( T < 900°C), the oxidation follows a phase-boundary reaction; the reaction product initially consists of aggregates of submicrometer needlelike TiO₂ rutile crystals that subsequently grow and coalesce. When a continuous TiO₂ rutile layer is formed ( T ≥ 900°C), the oxidation kinetics change to parabolic, and the diffusion of O₂ through a thick TiO₂ layer is proposed as the governing step.     

Oxidation Behavior of Titanium Boride at Elevated Temperatures

The oxidation behavior of dense TiB₂ specimens was investigated. Hot-pressed TiB₂ with 2.5 wt% Si₃N₄ as a sintering aid was exposed to air at temperatures between 800° and 1200°C for up to 10 h. The TiB₂ exhibited two distinct oxidation behaviors depending on the temperature. At temperatures below 1000°C, parabolic weight gains were observed as a result of the formation of TiO₂( s ) and B₂O₃( l ) on the surface. The oxidation layer comprised two layers: an inner layer of crystalline TiO₂ and an outer layer mainly composed of B₂O₃. When the oxidation temperatures were higher than 1000°C, gaseous B₂O₃ was formed along with crystalline TiO₂ by the oxidation process. In this case, the surface was covered with large TiO₂ grains imbedded in a highly textured small TiO₂ matrix.     

钛制设备的设计与制造

介绍了钛材的化学、物理性能、力学性能以及耐腐蚀性能,并根据醋酸乙烯装置中钛制设备的设计实例,阐述了钛制换热器和塔器的结构设计特点、技术要求、以及加工、焊接及热处理工艺.     

钛薄膜阳极氧化制备纳米孔结构TiO2

采用物理气相沉积的方法,以导电玻璃为基材沉积金属Ti薄膜,并将其作为阳极,在1% HF溶液中恒压阳极氧化,制备了具有纳米孔阵列结构的TiO2薄膜.研究表明,形成的TiO2薄膜具有多孔结构,微孔均为贯穿孔,孔形基本为圆形,孔径均匀,孔径大约为50 nm.在15℃溶液中阳极氧化相同时间制备的TiO2氧化膜的厚度显著大于25℃溶液制备的氧化膜厚度.TiO2氧化膜的厚度随着阳极氧化时间的延长而增加.     

Kinetics of Titanium(IV) Chloride Oxidation

The oxidation rate of TiCl₄ vapor was measured by FTIR spectroscopy between 700° and 1000°C in a furnace aerosol reactor. The reaction rate was found to be first order with respect to TiCl₄ and to follow the Arrhenius form. The apparent activation energy for the reaction was 88.8 ± 3.2 kJ/mol and the preexponential factor 8.26 × 10⁴ s⁻¹. A kinetic mechanism for the oxidation of TiCl₄ was proposed that was consistent with the observed dependence of oxygen concentration on the apparent rate constant.     

钛管制作及安装工艺

钛具有优异的抗腐蚀性.常温下,金属钛表面容易形成一层保护性氧化膜,不受水、硝酸、稀硫酸、稀盐酸和稀碱溶液的侵蚀,对海水的抗腐蚀能力特剐强.氢氟酸、磷酸和中等强度的碱对钛有侵蚀作用.钛管安装主要应用于石油、化工和热能电站等工业部门,而钛管件(如弯头、三通及异径管等)与管子的连接是其重要组成部分.根据多次调查,钛装备中管件与管子连接处事故率较高,这与该处断面工况条件陡变和受力较为恶劣有关.因此,钛管制作、安装工艺的技术要求就显得非常重要.文中主要从化工厂醋酸管线钛管的制作、焊接以及吹扫试压安装工艺方面加以阐述.     

均相沉淀-发泡法制备纳米氧化钛及其表征分析

采用Ti（SO4），和尿素为原料，利用均相沉淀．发泡工艺制备出了纳米氧化钛粉体材料，并用DTA-TG、XRD、IR和FS等方法对样品进行了表征。DTA-TG结果表明TiO2样品在高温固相反应期间有两个明显的失重台阶。XRD分析表明，在500℃下焙烧的TiO2样品为相纯度较高的锐钛矿型氧化钛粉体，其平均粒径约为12．834nm。IR谱图显示随着烧结温度的升高，450～800cm^-1处Ti-O键的伸缩振动峰出现分裂，且峰形逐渐锐化，表明纳米样品的尺寸有所增大。FS分析表明在365nm激发波长下，600℃煅烧下生成的混合晶型的纳米氧化钛具有最强受激发射峰，而在393nm激发光下。500℃煅烧下生成的锐钛矿型氧化钛具有最强受激发射峰。     

二氧化钛与血红蛋白相互作用的光谱研究

利用紫外可见吸收光谱和荧光光谱研究了自制的TiO2与血红蛋白在两种酸度条件下的相互作用,并对两者相互作用的机理进行了初步探讨。     

GHH烟气膨胀机叶片的国产化及使用情况分析

简要介绍了石家庄炼油厂GHH公司生产的烟气膨胀机叶片国产化情况、使用中出现的问题以及改进方法，肯定了进口机组叶片国产化的工作思路。     

Fabrication and characterization of graphene oxide modified polycarboxylic by in situ polymerization

Graphene oxide (GO) was modified by in situ esterification reaction with isopentenol polyoxyethylene ether (IPEG) to obtain GO precursor (GO-IPEG) with some polymerization activity. GO-modified polycarboxylic (GO-PCE) was prepared by GO-IPEG and acrylic acid (AA) using the method of in situ polymerization. The molecular structure of GO-IPEG and GO-PCE was characterized by Fourier transform infrared spectroscopy (FTIR), Raman spectra, and nuclear magnetic resonance (NMR). The dispersion properties and dispersion stability of GO-IPEG and GO-PCE in water solution were studied by ultraviolet–visible (UV–vis) absorption spectra, zeta potential, and atomic force microscope. The results of FTIR, Raman, ¹H-NMR, and ¹³C-NMR indicate that IPEG was successfully grafted onto the surface of GO and then fabricated with AA by in situ free-radical polymerization. The results of UV–vis and zeta potential show that GO nanosheets have a better dispersion in GO-IPEG or GO-PCE system when the reaction time of GO and IPEG is 1 h, and the dispersion stability can reach up to 1 month. The better dispersion and application property are confirmed by atomic force microscopy image and cement fluidity, water reducing rate, and compression strength. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48316.     

表面修饰的Fe~(3+)/TiO_2制备研究

采用微波水热法制备了表面包覆有硬脂酸的铁掺杂的二氧化钛纳米粒子,对其微结构进行了表征。结果表明:产物为表面包覆有硬脂酸Fe3+ /TiO2 的纳米复合粒子,粒度分布均匀且单分散性好,平均粒径约为38nm;表面为非极性,紫外透过率较低,催化活性较低。可用于防晒化妆品。     

分散剂对二氧化钛分散性能的影响

用沉淀法来研究超细二氧化钛在水中的分散情况,对比了自制产品丙烯酸-2-丙烯酰胺-2-甲基丙磺酸共聚物（AMAMPS）钠盐和国外分散剂产品YUS-WG5（聚羧酸酯）在不同分散剂用量、不同溶液的pH值时对水相中二氧化钛分散情况的影响,实验证明两者的分散性能相当,可以替代国外产品进行使用。