ELECTROCHEMICAL AL2O3-ZRO2 COMPOSITE COATINGS ON NONOXIDE CERAMIC SUBSTRATES

Aqueous solutions of xAl(NO3)(3)+(1-x)ZrO(NO3)(2) were used for electr odeposition of ceramic Al2O3-ZrO2 composite coatings on TiC, TiB2 and SiC substrates. The weight of the deposit was studied versus the durat ion of deposition, the current density and the temperature of the bath for Al-rich (x=0.9), Zr-rich (x=0.4) and eutectic (x=0.75) electrolyt e compositions. Optimal current densities and durations of deposition were determined to obtain maxima weights of deposits. Amorphous deposi ts with thicknesses up to 10 mu m were formed. The microstructure and microchemical composition of the as-deposited and sintered deposits we re characterized. Increase in the temperature of the bath inhibited mi crocracking due to shrinkage during drying. Coated TIC substrates exhi bited enhanced oxidation resistance in air at 1100 degrees.