PURPOSE: To inspect whether a steel plate is suitable for a heat collector plate of a solar water heater or not at the stage of shipping and improve the yield of the products by a method wherein a solutionof sulfuric acid and sodium dichro- mate is introduced and an anode polarization diagram is mesured under the specific conditions and the products are classified.
CONSTITUTION: A solution which contains 10W50wt% of sulfuric acid and 0W 30wt% of sodium dichromate is introduced. An anode polarization diagram is measured at the temperature of 15W50°C and with a potential sweep rate of not higher than 50mV/min and the roducts whose maximum current density exceed 80mA/cm2 are selected to be suitable material. The magnitude of the maximum current density depends closely upon the formation of a satisfactory selective absorption film and when the satisfactory selective absorption film is obtained on the surface of a stainless steel plate, the maximum current density value 3 on that surface is larger than that of the surface on which the satisfactory selective absorptionfilm is not obtained 4.
KURAHASHI HAYAO
ONO HIROSHI
Next Patent: CALIBRATION SYSTEM OF AMYLASE MEASUREMENT APPARATUS