DTA STUDIES ON THE CORROSION BEHAVIOR OF TITANIUM POWDER IN NACL AND NA2SO4

The corrosion/oxidation behavior of titanium powder in air and in the presence of corrodents NaCl and Na2SO4 was investigated by employing the DTA technique. The DTA results for pure and fine titanium powder in air indicate two high-temperature exotherms, one at 700° and the other at around 750°. The first exotherm is due to the formation of anatase (TiO2) and the second to rutile (TiO2), as evidenced by the XRD data. However, the presence of NaCl and Na2SO4 promote the direct oxidation of titanium to rutile, which is indicated by a large exotherm ranging between 600 and 850°. The endotherm at 690° for mixtures containing 25 to 30% NaCl to Na2SO4 corresponds to formation of the eutectic mixture. The DTA data clearly indicate that the presence of the corrodents not only lowers the temperature of oxidation, but also induce the catastrophic oxidation of titanium powder. © 1990 Wiley Heyden Ltd, Chichester and Akadémiai Kiadó, Budapest.