2002 年 53 巻 1 号 p. 49-53
β-titanium alloys are convenient as eyeglass frame materials because they are light and have good cold-workability and corrosion resistance. However, hydrogen penetrates easily into them by cathodic reaction, which may cause hydrogen embrittlement. Measuring the diffusion coefficient of dissolved hydrogen around room temperature is important to prevent breakage by hydrogen embrittlement.
In the present work, the entry of hydrogen into Ti-22V-4Al alloy caused by cathodic polarization in sulfuric acid solution at 298K was examined by using the heating extraction method. The catholic polarization introduced a large amount of hydrogen into the titanium alloy. The hydrogen atoms dissolved in the titanium alloy were stable and evolution of hydrogen was negligibly small at room temperature. To obtain the diffusion coefficient of hydrogen DH, the polarization time dependence of the hydrogen concentration was examined. DH at 298K was determined to be 4.8×10-14m2/s and the activation energy for diffusion of hydrogen was found to be 36kJ/mol by analysis of the thermal spectra of the hydrogen evolution rate.