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1.
Fabrication of Titanium Carbide-Alumina Composites by Combustion Synthesis and Subsequent Dynamic Consolidation 总被引:8,自引:0,他引:8
Barry H. Rabin Gary E. Korth Richard L. Williamson 《Journal of the American Ceramic Society》1990,73(7):2156-2157
Dispersed-phase composites of TiC-Al2 O3 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. 相似文献
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Kanichi Kamiya Tomoaki Nishijima Katsuhisa Tanaka 《Journal of the American Ceramic Society》1990,73(9):2750-2752
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 -C3 H7 )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. 相似文献
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金属氧化物半导体气敏传感器的研究和开发进展 总被引:13,自引:0,他引:13
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。 相似文献
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Takamasa Ishigaki Ya-Li Li Eiji Kataoka 《Journal of the American Ceramic Society》2003,86(9):1456-1463
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 Ti4 O7 and Ti3 O5 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. 相似文献
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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. 相似文献
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Valeria Tohver Sherry L. Morissette Jennifer A. Lewis Bruce A. Tuttle James A. Voigt Duane B. Dimos 《Journal of the American Ceramic Society》2002,85(1):123-128
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. 相似文献
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Seiji Adachi Takahiro Wada Toshihiro Mihara Yoshinari Miyamoto Mitsue Koizumi Osamu Yamada 《Journal of the American Ceramic Society》1989,72(5):805-809
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. 相似文献
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The presence of TiC or TiN paritcles in an Al2 O3 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. 相似文献
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Oxidation Behavior of Titanium Boride at Elevated Temperatures 总被引:3,自引:0,他引:3
Young-Hag Koh Seung-Yong Lee Hyoun-Ee Kim 《Journal of the American Ceramic Society》2001,84(1):239-241
The oxidation behavior of dense TiB2 specimens was investigated. Hot-pressed TiB2 with 2.5 wt% Si3 N4 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 B2 O3 ( l ) on the surface. The oxidation layer comprised two layers: an inner layer of crystalline TiO2 and an outer layer mainly composed of B2 O3 . When the oxidation temperatures were higher than 1000°C, gaseous B2 O3 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. 相似文献
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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. 相似文献
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Sotiris E. Pratsinis Hebi Bai Pratim Biswas Michael Frenklach Sebastian V. R. Mastrangelo 《Journal of the American Ceramic Society》1990,73(7):2158-2162
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. 相似文献
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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。 相似文献
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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。 相似文献
18.
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. 相似文献
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