In order to reduce the amount of platinum particles in conductive paste for oxygen sensor of automobile, uniform Pt spherical powder and platinum coated alumina powder were prepared and used for the preparation of conductive paste. The specific resistance of conductive paste prepared from uniform Pt spherical powder was lower than that of the paste mixed with non uniform conventional commercial Pt powder. When pure alumina content increased from 10 to 15%, the specific resistance of conductive paste prepared from platinum coated alumina powder was shown lower value compared with mixed paste of conventional non-uniform Pt and alumina powder.

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The powder particle packing state of green body is important for determine its density. The powder which median diameter is 0.4μm was blended to the powders of 0.78μm and 3μm at median diameter, in gel-casting slurry. The packing density was calculated by model of Suzuki et al. “The theoretical packing density” was calculated from synthesized particle size distribution with two particle size distribution of powders. “The estimated packing density” was calculated from measured particle size distribution of slurry. The theoretical and estimated packing density are hard to have correlation by effect of agglomeration. When the powder of 0.4μm at median diameter was blended to 0.78μm powder, behavior of “The estimated packing density” with blending ratio was different with “The theoretical packing density”. However, in case of blending to 3μm powder, “The estimated packing density” behaves like “The theoretical packing density”. From measurments of viscosity and particle size distribution at slurry, the aggregation of particles are reduced in the powder of 3μm at medium diameter. By reducing effect of agglomeration, it is estimated that the model of Suzuki et al. is able to be used for estimating the condition for fabricating the dense green body, in gel-casting method.

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Organic polymer particles have mainly been used in the form of film in paint and adhesive industrial sections. In addition to usage in the form of the film, there have been increasing interests in using the polymer particles in their particulate form. The polymer particles have been used as absorbents, ion-exchangers, affinity bioseparators, drug and enzyme carriers, viscosity modifiers, calibration standards, and functional beads for medical diagnostics. Studies on the foams and liquid marbles stabilized with polymer particles have recently been started. In principle, organic particles should be particularly attractive for preparing foams and liquid marbles, since they can be readily designed with specific surface chemistries.
In this paper, the author would like to present our recent works on foams and liquid marbles stabilized with well-defined polymeric colloidal particles.

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