Sridhar Venigalla

A review of the aqueous chemistry of the zirconium-water system to 200 C

The aqueous chemistry of the Zr-H{sub 2}O system is reviewed. It is shown that the thermodynamically stable solid phase for the Zr-H{sub 2}O system at 25 C is the monoclinic phase. After a review of the chemistry of the pure material in water, a summary of the solution equilibria of the Zr-H{sub 2}O system is presented followed by a discussion of the aqueous phase stability of the monoclinic and tetragonal phases of the pure ZrO{sub 2} system. Last, a discussion of the phase stability of the complex metal oxides, particularly the Y{sub 2}O{sub 3}-containing TZP in aqueous solution will be reviewed. It will be shown that the phase stability for the complex metal oxide-zirconia systems may be best understood as corrosion with the alloying agent (e.g., Y{sub 2}O{sub 3}) subject to leaching from a zirconia-rich interface.

Preparation and characterization of barium titanate electrolytic capacitors by anodic oxidation of porous titanium bodies

Low-temperature (50-60 degrees C) anodic oxidation of porous titanium bodies in an aqueous electrolyte containing Ba/sup 2+/ in solution has been used to infiltrate BaTiO/sub 3/ onto a large surface area. Microstructural and dielectric characterization indicates the possibility of achieving extremely high capacitance values by further improving the porosity of the Ti bodies and electroding the BaTiO/sub 3/ surface using electroless plating techniques.<<ETX>>