Corrosion Resistance of Tantalum-Oxide Films Deposited by PLD

Tantalum-oxide films were deposited on SUS304 by PLD under O2 gas and 5 mass% O3 gas at room temperature. Effects of atomic ratio of O/Ta and Ta-O binding state on corrosion resistance of tantalum-oxide films were investigated systematically. Corrosion resistance of the films was examined by the measurement of anodic polarization curve in 3.5 mass% NaCl solution. The penetrated potential of the films deposited under O2 gas as well as 5 mass% O3 became higher with the atomic ratio of O/Ta increased. The film deposited under 5 mass% O3 gas at 10Pa had excellent corrosion resistance equal to Ta plate. Moreover, in order to evaluate of corrosion process, anodic polarization test was examined up to 200mV. The pits depth of the films deposited under 5 mass% O3 gas was shallower than that under O2 gas because of its stable Ta-O combination.