Masamichi Kowaka

Amorphization of electrodeposited FeW alloy films and electrochemical behavior

Abstract The FeW crystalline and amorphous films are prepared by electrodeposition in various conditions. Threshold value of W content of amorphous structure is 40 wt% when the deposition is made at 30C. The studies on the relation between crystal structure and mechanical and electrochemical properties have been performed. Amorphization of the films with W content improves the electrochemical properties. The activation energy of crystallization is obtained as 113 kcal/mol by DTA. The mechanism has been discussed.

Surface modification of amorphous FeW alloy deposits

Abstract The corrosion resistance of amorphous FeW alloy deposits is excellent in acid solutions, but poor in neutral or basic solutions, especially when Cl − is involved. Therefore, the amorphous deposit was passivated chemically and electrochemically in chromate solutions in order to form a passive film containing Cr 6+ . Anodic polarization curves show that the pitting potential of passivation moves about 1.68 V toward noble values. Immersion tests show that amorphous FeW deposits are corroded severely within an hour in NaCl solution, but the passivated deposit exhibits no change and still has a metallic luster on the surface after 1 month of immersion.

Electrodeposition of Amorphous Fe-Cr-Ni-P Alloys and Their Polarization Behavior

Fe-Cr-Ni-P alloys were electrodeposited from a sulfate-glycine bath, and a determination of the influence of bath composition on their composition, and of the condition for amorphous formation was made. The polarization behavior of the alloy deposits was investigated in an acidic solution.It was found that amorphous Fe-Cr-Ni-P alloy deposits were obtained over a wide range of bath compositions. Based on anodic polarization curves in 1N hydrochloric acid at 30°C, it was shown that the presence of chromium and phosphorus in the amorphous alloy deposits have a favorable effect on their corrosion resistance, and that the presence of nickel was effective in increasing the stability of passive films formed in acidic solutions. The same outstanding corrosion resistance was shown under comparision with the anodic polarization curve of Hastelloy C-276.