Preparation method of alpha-type iron oxyhydroxide film layer

The invention belongs to the technical field of inorganic materials, and particularly relates to a preparation method of an alpha-type iron oxyhydroxide film layer. The preparation method comprises the following steps: placing the substrate in an aqueous solution containing ferric nitrate and urea, carrying out ultrasonic treatment, and depositing the alpha-type iron oxyhydroxide film layer on the substrate. By using ferric nitrate, the obtained FeOOH film layer is single alpha-FeOOH, the crystal phase structure is uniform, the thickness of the film layer is uniform and is 2-15 microns, and the FeOOH film layer is firmly combined with a matrix. The preparation method is high in speed, the deposition process only needs dozens of seconds to several minutes, and even for common carbon steel, obvious corrosion cannot be caused to a matrix. And the method has wide applicability and can be deposited on the surfaces of steel, ceramics, glass and the like. The method is green and environment-friendly, and the alpha-t