CORROSION LIFE DIAGNOSING APPARATUS FOR ZINC GALVANIZED STEEL

摘要

PURPOSE:To display the average corrosion rate or the like handily and accurately, by measuring the thickness of a zinc oxide layer of a zinc galvanized steel and the thickness of a residual zinc galvanized layer with an electromagnetic induction sensor alone to compute the corrosion life of the zinc galvanized steel from these value. CONSTITUTION:When a sensor section 9 is placed on a zinc galvanized steel plate, the impedance of an AC coil is determined in proportion to the sum t0 of thickneses of a zinc oxide layer 12 and a residual zinc galvanized layer 11 as the conductivity and the magnetic permeability of iron ground and fixed. Therefore, when the iron ground 10 is magnetized and saturated by a magnetic field of a DC coil 2, the impedance of an AC coil 1 is determined in proportion to the thickness t1 of the zinc oxide layer 12. An arithmetic unit 5 calculates the sum t0 of thickness and the value of the thickness t1 to compute the thickness t2 of the residual zinc galvanized layer 11.