Preparation of Activated Carbon Functional Ceramics From Coal Pitch

The influences of different impregnation temperatures,pre-oxidation,carbonization temperatures and activation conditions on the iodine value and carbon deviations was discussed.SEM,EDS,and BET techniques were used to investigate the microstructures and properties of materials.Results showed that activated carbon functional ceramic exhibited excellent comprehensive properties when porous ceramics adsorbed the coal pitch at 150 ℃ for 0.5 h,oxidized at 420 ℃ for 1.0 h,and carbonizated at 700 ℃ for 1.0 h and then activated by using KOH（20wt%） as agent at 800 ℃ for 1.0 h,as confirmed by the high iodine value（162.6 mg/g） and high specific surface area（83.5 m2/g）.

Research on Chemical Mechanical Planarization for Functional Ceramics

Presently, the products of functional ceramic are widely applied in the light & mechatronics fields such as communication, aeronautic and astronautic engineering, military affairs and home-use electrical appliance etc. It’s performance of working is mainly determined by the physical performance of the surface. And therefore the roughness and the affected layer’s depth of the final processing surface have a direct influence to the performance of the device. It is obvious that how to guarantee the processing quality of functional ceramic is a kernel problem whether it can achieve the purpose of application or not. Ultra-precision planarization is usually as the final processing method of functional ceramic substrates, and the mirror surface of Ra 0.01～0.002 μm can be obtained by ultra-precision polishing. For the ultra-precision planarization processing of functional ceramic material, simplex chemical or mechanical polishing method is very difficult to achieve the technic demands, and furthermore various defects of processing exist in the surface of crystal after planarization. However, chemical mechanical planarization (CMP) which has emerged recently as a new indispensable processing technique for higher degree planarization of functional ceramic is be able to satisfy the processing requests from the aspects of processing performance and rate. The current paper systematically introduces the processing course of functional ceramic by using chemical mechanical planarization. In addition, material removal mechanism is analyzed, and the choosing of processing conditions and components and effect of polishing slurry are discussed. Then the present research status and development trend of CMP technology for functional ceramic are discussed. Finally the current existing main questions and their solutions are presented.

Fabrication and Characterization of Diatomite-supported Activated Carbon Functional Ceramic

Using porous diatomite ceramic as carrier and phenolic resin as carbon precursor, the activated carbon functional ceramic with the activated carbon fixed into porous ceramic was prepared by the impregnation load phenolic resin, carbonization and activation isolated air. The influences of impregnation, curing, carbonization, activation etc. on the material property were discussed. The iodine value, SEM, elemental analyzer, BET and spectrum analysis chart were used to characterize the microstructures and performance of material at different conditions. The results showed that the excellent comprehensive property of activated carbon functional ceramic was gained when it adsorbed phenolic resin in 4 h under vacuum condition at curing temperature of 150 ℃ for 0.5 h and carbonization temperature of 600 ℃ for 1.0 h, and then put into 25wt% KOH for 4.0 h at activation temperature of 700 ℃ for 1.5 h. The iodine value is 176.9 mg/g, the specific surface area can reach 86.3 m2/g and the yield of carbonization is 50.48%.

Stress Field Analyses of Functionally Gradient Ceramic Tool by FEM

The cutting properties of the functionally gradient ceramic cutting tools relate closely to the gradient distribution. A cutting model of the functionally gradient ceramic tool is firstly designed in the present paper. The optimum of gradient distribution is obtained by way of the FEM analyses.

Local Structure Analysis of Lead Zinc Niobate-Barium Titanate Ceramic by X-Ray Absorption Spectroscopy and Density Functional Calculation

The local structure of an alternative Pb（Zn1/3Nb2/3）O3-based perovskite ceramic is investigated. The 0.07BaTiO33-0.93Pb（Zn1/3Nb2/3）O3 ceramic is synthesized using a combination of Zn3Nb2O8 B-site precursor and BaTiO33 perovskite phase stabilizer. Then, x-ray absorption spectroscopy and density functional theory are employed to calculate the local structure configuration and formation energy of the prepared samples. Ba2＋ is found to replace Pb2＋ in AA-site with Zn2＋ occupying BB-site in Pb（Zn1/3Nb2/3）O3, while in the neighboring structure, Ti4＋4＋ replaces Nb5＋5＋ in BB-site with Pb2＋2＋ occupying AA-site. With the substitution of BaTiO33 in Pb（Zn1/3Nb2/3）O3, the bond length between Zn2＋ and Pb2＋ is longer than that of the typical perovskite phase of Pb（Zn1/3Nb2/3）O3. This indicates the key role of BaTiO33 in decreasing the steric hindrance of Pb2＋ lone pair, and the mutual interactions between Pb2＋ lone pair and Zn2＋ and the formation energy is seen to decrease. This finding of the formation energy and local structure configuration relationship can further extend a fundamental understanding of the role of BaTiO33 in stabilizing the perovskite phase in PbZn13Nb23O3-based materials, which in turn will lead to an improved preparation technique for desired electrical properties.

PHASE-FIELD SIMULATION FOR MICROSTRUCTURAL DEVELOPMENT OF TEXTURED CERAMICS PREPARED BY REACTION TEMPLATED GRAIN GROWTH

A modified model using phase-field method in order to describe the microstructural development for the reaction templated grain growth process was developed.The current model well expressed anisotropic enlargement of the template particles.The initial parameters such as the matrix particles size,the template particles size,fraction,aspect ratio of the template particles and porosity were examined.The simulation results show that the fraction of oriented grains increases with decreasing the matrix particles size and porosity,and increasing the fraction of the initial template particles.An increase for the aspect ratio of template particles gives rise to the anisotropic microstructure development.The study suggests that the simulation results would give a guiding principle in terms of the initial preparation conditions for the textured ceramics having both a large fraction of oriented grains and anisotropic microstructure.

Electrospinning of ceramic nanofibers:Fabrication,assembly and applications

This paper provides a brief review of current research activities that focus on the synthesis and controlled assembly of inorganic nano-bers by electrospinning,their electrical,optical and magnetic properties,as well as their applications in various areas including sensors,catalysts,batteries,filters and separators.We begin with a brief introduction to electrospinning technology and a brief method to produce ceramic nanofibers from electrospinning.We then discuss approaches to the controlled assembly and patterning of electrospun ceramic nanofibers.We continue with a highlight of some recent applications enabled by electrospun ceramic nano-bers,with a focus on the physical properties of functional ceramic nanofibers as well as their applications in energy and environmental technologies.In the end,we conclude this review with some perspectives on the future directions and implications for this new class of functional nanomaterials.It is expected that this review paper can help the readers quickly become acquainted with the basic principles and particularly the experimental procedure for preparing and assembly of 1D ceramic nanofiber and its arrays.

Temperature-dependent dielectric anomalies in powder aerosol deposited ferroelectric ceramic films

Room-temperature fabrication of functional ceramic films using powder aerosol deposition(AD)is important for practical applications.However,the as-processed ferroelectric films show unusual temperature-dependent dielectric response,including enhanced conductivity in the as-processed state and subsequent significant increase in the permittivity following heat treatment.In this work,we investigate the influence of the residual internal stresses developed during the high-impact consolidation process on the dielectric response.Moreover,the recombination of charged defects generated during deposition is driven by the temperature and the atmospheric condition during the heat treatment as well as the carrier gas type used during deposition.Thermal treatment up to 500℃ in different atmospheres was used to tune the dielectric and ferroelectric response,highlighting that irrespective of the type of carrier gas,AD deposition process induces charged defects in polar oxide ceramics that can be reduced through heat-treatment far-below their bulk sintering temperature.Macroscopic electromechanical properties are contrasted to in-situ heating scanning transmission electron microscopy to observe possible local effects,such as crystallization,grain growth,crystal defect structure,or grain reorientation.In addition X-ray diffraction and X-ray photoelectron spectroscopy studies were conducted to gain insight into the effect of annealing on the crystal structure and local moisture adsorption.