Al2O3 coating on Pt wire by the electrophoretic deposition

The effect of powder characteristics (such as specific surface area and morphology) and iodine addition on the electrophoretic deposition (EPD) coating of alumina on Pt wire was investigated. Electrical conductivity of the bath solution was increased by adding iodine and depended upon specific surface area of alumina powder. Moreover, adding a suitable amount of iodine led to a remarkable improvement of stability of the bath solution, and uniform EPD layers resulted. Round shaped alumina produced by chemical vapor deposition (CVD) method was more suitable than irregular shaped alumina made by sol-gel method for preparing thick and uniform layers. The difference of deposition behavior was explained in terms of electrical resistance of the formed alumina layer and the bubbling of H-2 gas generated during deposition. Crack-free alumina similar to 50 mu m thick layers could be formed on Pt wire by sintering at 1500 degrees C.