The addition of Cr to intermetallic compound FeAl improves its corrosion resistance in HCl aqueous solution. Furthermore, corrosion resistance effects of FeAl containing additional Ni and Cu, which improve the steel corrosion resistance, were assessed during immersion in 0.1 mol/L HCl aqueous solution. Results show that the addition of Ni or Cu reduced the FeAl corrosion rate similarly to the addition of Cr. The FeAl corrosion rate was reduced to 1/9 by the addition of Ni, and to 1/16 by the addition of Cu, and to approximately zero by the addition of Cr. The FeAl contained 12 at% Ni and the FeAl contained 12 at% Cu, which showed superior corrosion resistance to that of SUS430. The FeAl containing 12 at% Cr showed superior corrosion resistance to that of SUS304.
A coulomb controller is a device that accurately controls the quantity of electricity used for each layer during potentiostatic multilayer electrodeposition using the single bath method. The device was developed to improve the controllability of the amount of electrodeposited material. Co-Cu/Cu multilayers were electrodeposited using the coulomb controller with a target layer thickness of 50 nm to investigate the effectiveness of coulostatic electrodeposition. Current and X-ray fluorescence analyses showed that the total mass of Co-Cu and Cu layers in a sample were proportional to the integrated current used for the electrodeposition of each layer type. Current efficiencies were relatively high and the mass of electrodeposited material was stabilized by the coulomb controller. Consequently, variations in the effective substrate area became obvious as the cause of variation in the layer thickness. When the coulostatic method was employed, the time at which the intended electrodeposition would be completed was not predetermined. Therefore, there was an unavoidable time lag to remove a sample from the plating bath after completion of the intended electrodeposition, during which time, a part of the sample was re-dissolved in the bath.