THIN OXIDE FILMS ON TITANIUM, ZIRCONIUM, MOLYBDENUM AND ALLOYS OF TITANIUM

The kinetics of the oxidation of Ti, Zr, Mo, a Ti alloy with 10% Mo, and a Ti alloy with 3% Al and 5% Cr at a temperature of 50 to 400 ts C were studied by determining the increase in thickness of the oxide layer by means of a method based on the polarization of reflected light. The oxidation became noticeable at 50 ts C for Zr, 100 ts C for Ti and the Ti alloy with 10% Mo, and at 150 ts C for Mo and the Ti alloy with 5% Cr and 3% Al. The rats of oxidation is expressed by the equation L = k lg (k/ sub 1/ t + k/sub 2/) where L is the thickness of the oxide layer and t is the time of oxidation. At higher temperatures the parabolic expression L/sup 2/ = k/ sub 3/t determined the rate of oxidation. The more rapid increase in thickness of the oxide film started at 200 ts C for Zr and Mo and at 350 ts C for the Ti alloy with 10% Mo, Ti itself, and the Ti alloy with 5% Cr and 3% Al. The composition of the oxide film atmore » various temperatures is discussed. The addition of molybdenum to titanium improved the oxidation resistance of titanium. Water vapor had a protective action on the oxidation of titanium below 200 ts C. (TTT)« less