• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.53-53
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• 2008

Piezoelectric transformers have been widely used such as DC-DC convertor, invertor, Ballast, etc. Because, the y have some merits compared with electro-magnetic transformers such as step-up ratio, high efficiency, small size and lg hit weight, etc. Piezoelectric transformer require high electromechanical coupling factor kp in order to induce a large out put power in proportional to applied electric field. And also, high mechanical quality factor Qm is required to prevent mechanical loss and heat generation. In general, PZT system ceramics should be sintered at high temperatures between 1200 and $1300^{\circ}C$ in order to obtain complete densification. Accordingly, environmental pollution due to its PbO evaporation. Hence, to reduce its sintering temperature, various kinds of material processing methods such as hot pressing, high energy mill, liquid phase sintering, and using ultra fine powder have been performed. Among these methods, liquid phase sintering is basically an effective method for aiding densification at low temperature. In this study, In order to comparis on low temperature sintering and solid state sintering piezoelectric transformers, rosen type transformers were fabricated u sing two PZT ceramics compositions and their electrical properties were investigated.

• Journal of Powder Materials
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• v.15 no.2
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• pp.101-106
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• 2008

The objective of the present study is to investigate the increase in the functional characteristics of a substrate by the formation of a thin coating layer. Thin coating layers of $Ti_5Si_3$ have high potential because $Ti_5Si_3$ exhibits high hardness. Shock induced reaction synthesis is an attractive fabrication technique to synthesize uniform coating layer by controlling the shock wave. Ti and Si powders to form $Ti_5Si_3$ using shock induced reaction synthesis, were mixed using high-energy ball mill into small scale. The positive effect of this technique is highly functional coating layer on the substrate due to ultra fine substructure, which improves the bonding strength. These materials are in great demand as heat resisting, structural and corrosion resistant materials. Thin $Ti_5Si_3$ coating layer was successfully recovered and showed high Vickers' hardness (Hv=1183). Characterization studies on microstructure revealed a fairly uniform distribution of powders with good interfacial integrity between the powders and the substrate.