D.S. Jung

Electrical and morphological properties of conducting layers formed from the silver–glass composite conducting powders prepared by spray pyrolysis

Ag-glass composite powders with various glass contents and excellent conducting properties were prepared by spray pyrolysis. Irrespective of the glass content, all the prepared powders were found to comprise spherical particles with nonaggregation characteristics. The crystal structure of the powder particles resembled that of pure Ag particles, irrespective of the glass content. Conducting layers formed from pure Ag did not melt even when sintered at 400 degrees C. On the other hand, conducting layers formed from composite powders containing 3 and 5 wt% glass melted when sintered at 400 degrees C. The optimum glass content of the composite powders was 3 wt% at sintering temperatures of 400 and 450 degrees C. However, the optimum glass content decreased to 1 wt% when the sintering temperature was increased to 550 degrees C. The lowest specific resistances of the conducting layers formed from the composite powders were 5.3 and 2.3 microohms-cm at sintering temperatures of 400 and 550 degrees C, respectively.

Properties of Bi-based glass powders with low glass transition temperature, spherical shape and fine size as the additive of silver conducting paste

Bi-based glass powders with low glass transition temperature of 373°C for silver paste were directly prepared by spray pyrolysis at 1200°C. The mean size and geometric standard deviation of the glass powders with spherical shape were 0.75 µm and 1.3. The glass film formed from the prepared glass powders had clean surface and cross-section at a firing temperature of 450°C. Adhesion properties between the silver electrode and glass substrate improved with increase of the addition amount of glass powders into silver paste and the firing temperatures. The addition of glass powders decreased the sheet resistances of the silver conducting films irrespective of firing temperatures. The sheet resistances of silver conducting films were changed from 7.7 to 5.5 µΩcm when the glass content added to the silver paste were changed from 0 to 5 wt. % at a firing temperature of 550°C.

Characteristics of Fe powders prepared by spray pyrolysis from a spray solution with ethylene glycol as the source material of heat pellet

Fe powders as the heat pellet material for thermal batteries are prepared from iron oxide powders obtained by spray pyrolysis from a spray solution of iron nitrate with ethylene glycol. The iron oxide powders with hollow and thin wall structure produce Fe powders with elongated structure and fine primary particle size at a low reducing temperature of 615 °C. The mean size of the primary Fe powders with elongated structure decreases with increasing concentration of ethylene glycol dissolved into the spray solution. The heat pellets prepared from the fine-size Fe powders with elongated structure have good ignition sensitivities below 1 watt. The heat pellets formed from the Fe powders obtained from the spray solution with 0.5 M EG have an extremely high burn rate of 26 cms−1.