Development and Manufacturing of Maltilayr coated Ceramic-Composite Particles.

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The ultra-fine composite particles with multilayr coating of different compounds were investigated. Two types of approaches were applied. (1) Special surfactant containing with the target element in the molecular structure was adsorbed on the surface of the ceramic particle to realize the homogeneous coating and dispersion. (2) Liquid particles are formed by the ultrasonic nebulization of mixed solution of the element for forming particle and for the coating, dried and decomposed. During this reaction, formed particle was covered with different element.(1) Titanium tri-iso-stearoil iso-propoxide (TTI) was selected as a model surfactant. TTI was adsorbed on the surface of yttria stabilized zirconia (YSZ) particle to make homogeneous coating of Ti on its surface. YSZ with TTI were well dispersed in decane as a primary particle. Centrifugal force was applied to make ultra-fine particle films with homogeneously distributed Ti. Element analysis revealed the overall composition are well agreed with predicted value from adsorption isotherm.(2) Pd fine particles coated with Ca compound and SiO_2 ultra-fine particle were selected as a model material of the ultrasonic nebulization approach. Pd (NO_3)_2 was most suitable starting material to make dense and homogeneous particle under controlling the particle size by the hydrolysis reaction simultaneously occurred during drying. Adding the 55 ppm-1wt% of Ca (NO_3)_2 solution to the Pd starting solution, Ca compounds deposited on the surface of the formed Pd metal particle. This coating layr protected the Pd particle from oxidation during heating.Colloidal SiO_2 particle was also added into starting solution. At drying stage SiO_2 particles were homogeneously distributed in the particle that is PdO by the thermodynamic reason. However, SiO_2 particles migrated from inside of the Pd particle to the surface during decomposition of the PdO to Pd. Pd particle was covered with SiO_2 on the surface.