Effects of titanium carbide (TiC) and anodizing voltages on discoloration resistance of colored-titanium sheets

Discoloration resistance of anodized titanium sheets was investigated by accelerated discoloration tests and atmospheric exposure tests. Anodized oxide layers were analyzed by various surface analytical methods. TiC beneath the titanium oxide layer accelerated discoloration in cases where thinner oxide layers existed. Increase of their thickness improved resistance even though TiC existed. On the other hand, in case of reducing TiC, the specimen with the thinnest oxide layer showed the most resistant to discoloration. The top-surface region of the oxide layer is considered to play an important role in discoloration resistance.