CORROSION RESEARCH ROUND‐UP

GERMANY Corrosion of titanium. The voltage‐current diagram reveals several voltage ranges within which obtain specific corrosion characteristics. Above the minimum corrosion potential a layer of titanium hydride forms, making it passive (very strong cathodic polarisation). Exceeding a critical potential difference renders the process active and corrosion ensues with subsequent development of hydrogen. Exceeding the critical passivation potential difference leads to the formation of an oxide layer, becoming passive again. This oxide layer is responsible for the excellent corrosion resistivity of titanium. With high potentials due to anodic polarisation, activation is achieved in halo‐genide solutions, producing pitting. In the absence of halides there is no corrosion.—(W. R. Fischer, Werks. u. Korr., 1959, 10 (4), 243–250.)