Papers by Keyword: Solid State Processing

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Authors: S. Mohanasundaram, S.J. Vijay, M. Karthikeyan
Abstract: Friction surfacing is an localized surface modification process of depositing consumable materials over substrate. FS, utilizes FSW technology allows joining of materials while avoiding the brittle intermetallic formations, involving temperatures below melting point and producing fine grained structure, results in exhibiting bond integrity and enhanced surface properties, reducing the costs associated with energy consumption and consumables. The process is used for corrosion and wear resistant coatings and for reclamation of worn engineering components and for coating components using dissimilar materials. This review presents the essentials of FS, parameters used, performance features of this technique. This describes the influence of the process parameters on surface properties of the surface composites produced and evaluated of the different materials. The FS is compared with other coating processes, and some of the applications are emphasized. The paper also discusses on few trails of FS made by the authors and the results of which is presented.
Authors: Niti Yongvanich, Pattama Visuttpitukul, Waranya Assawasilpakul, Warunee Srichan, Nuttapol Sungsuwan
Abstract: In this work, systematic substitution of ZnO with SnO2 in ZnO-based varistor composition was investigated through analysis of densification, phase formation, microstructure and non-linear properties. The general formula was Zn0.96-xSnxBi0.02Co0.02Oβ with x = 0, 0.01, 0.02 and 0.04. The high rate of densification starting at 800°C is believed to be related to Bi2O3 via liquid-phase sintering. The complex nature of this multi-phasic varistor system was demonstrated through occurrence of different phases at different sintering temperatures. The low-temperature pyrochlore (Bi2Sn2O7) started to dissociate at approximately 1100°C with the spinel (Zn2SnO4) forming afterwards. The grain size variation with composition might be induced by the changes in the availability of Bi2O3 which has been reported to help facilitate abnormal grain growth. All samples sintered at 1200°C, with data extrapolation, possessed breakdown voltages of higher than 1400 V/cm.
Authors: Jürgen Eckert, S. Scudino, P. Yu, C. Duhamel
Abstract: Nanostructured or partially amorphous Al- and Zr-based alloys are attractive candidates for advanced high-strength lightweight materials. The strength of such materials is often 2 – 3 times higher than the strength of commercial crystalline alloys. Further property improvements are achievable by designing multi-phase composite materials with optimized length scale and intrinsic properties of the constituent phases. Such alloys can be prepared by quenching from the melt or by powder metallurgy using mechanical attrition techniques. This paper focuses on mechanically attrited powders containing amorphous or nano-(quasi)crystalline phases and on their consolidation into bulk specimens. Selected examples of mechanical deformation behavior are presented, revealing that the properties can be tuned within a wide range of strength and ductility as a function of size and volume fraction of the different phases.
Authors: Mohd Fariz Ab Rahman, Julie Juliewatty Mohamed, Mohd Fadzil Ain, Sabar Derita Hutagalung
Abstract: The properties of undoped and Mg-doped CaCu3Ti4O12 (CCTO) ceramics have been studied. The samples were calcined at 900°C for 12 hours, and sintered at 1030°C for 10 hours. X-ray diffraction analysis on calcined samples shown the formation of CCTO phase with trace of secondary phases meanwhile completed formation of CCTO single phase obtained for sintered pellets. The peak positions of Mg-doped CCTO were slightly left-shifted from the undoped CCTO, attributed to the lattice expansion. Scanning electron microscopy analysis showed that the grains size becomes larger with the increment of dopant amount. Enhanced dielectric constant was observed in the Ca1-xMgxCu3Ti4O12 ceramics with x = 0.05 for the frequency range from 1 MHz to 1 GHz. The dielectric loss seem to be at lowest value when Ca1-xMgxCu3Ti4O12 ceramics with x = 0.10 at the same frequency range. The results indicate that Mg ions have effectively changed the properties of CCTO.
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