Patent ID: 7727372
Filing Date: 2010-06-01
Classification: C25D

Abstract:
1. A method for anodizing a valve metal structure to a target formation voltage, comprising the steps of: a) providing the valve metal structure; b) providing an anodizing apparatus comprising a power supply that generates a source voltage, a current limiting device, an anodizing electrolyte and a cathode; c) providing the valve metal structure in the anodizing electrolyte with the valve metal structure being connected to the current limiting device; and d) anodizing the valve metal structure to the target formation voltage by subjecting the valve metal structure to a current from the current limiting device that continuously decreases over time as a formation voltage continuously increases over time according to the following equation:  wherein V is the source voltage; Vf is the anode formation voltage (including IR drop due to electrolyte); k is the formation rate constant depending on the type of valve metal and sinter conditions; g is the mass of the valve metal; t is the formation time; and R is the resistance of the current limiting device until the target formation voltage is reached without interruption of the anodizing process.