Ferrite Plating by Means of Thin Film of Reaction Solution; "Thin Liquid-Film Method"

A new method is proposed for ferrite plating to overcome the disadvantages with the conventional ferrite plating based on the rotating disk method and spraying method. The ferrite film is grown in a stainless steel reaction cell, in which the reaction solution forms a "thin (~ 50 μm) liquid film" between a substrate and a cell wall. By intermittently introducing an oxidizing solution, which contains air as an oxidizing reagent, the metal ions (Fe²⁺, Co²⁺, etc) in the "liquid thin film" react into crystalline spinel film on the surface of the substrate. In the new method, oxygen concentration and the flow rate of the solution are much easier to control than in the previous method, and the reaction cell is much simpler too.