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MEASUREMENT METHOD AND MEASUREMENT DEVICE, AND CORROSION RESISTANCE TEST METHOD AND CORROSION RESISTANCE TEST APPARATUS FOR COATED METAL MATERIAL
MEASUREMENT METHOD AND MEASUREMENT DEVICE, AND CORROSION RESISTANCE TEST METHOD AND CORROSION RESISTANCE TEST APPARATUS FOR COATED METAL MATERIAL
Provided is a measurement method for measuring a size of expansion of a surface treatment film occurred in a coated metal material that includes a metal base and the surface treatment film provided on the metal base. The measurement method includes the steps of disposing a water-containing material to be in contact with the expansion and an electrode to be in contact with the water-containing material, and electrically connecting between the electrode and the metal base with an external circuit; applying, with the external circuit, a constant voltage between the electrode and the metal base, as a cathode and an anode, respectively, and measuring a current value flowing therebetween; and calculating a size of the expansion, based on the current value measured and a correlation between the current value and the size of the expansion, the correlation being determined on an exploratory basis in advance.
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