Patent ID: 8728294
Filing Date: 2014-05-20
Classification: C25D

Abstract:
1. A method of anodizing a workpiece made of aluminum or aluminum alloy, the method comprising: immersing the workpiece in an electrolytic solution in which a cathode is arranged; performing a tentative treatment in which an application of positive voltage and removal of charges by application of a negative voltage are repeated alternately, between the workpiece and the cathode, in a tentative cycle; increasing the starting positive voltage to a set positive voltage continuously or stepwise; measuring a peak arrival time of a current waveform at the positive voltage application period in the tentative cycle during the increasing of the positive voltage; determining an optimum positive voltage application time in a range of 0.6 to 3 times the peak arrival time during the increasing of the positive voltage; and performing a conclusive treatment in which the application of the positive voltage and the removal of charges by the application of the negative voltage are repeated in an optimum cycle corresponding to the optimum positive voltage application time, whereby an actually detected current waveform is maintained as continuous curves, to form an anodized film on the surface of the workpiece.