Patent ID: 9677187
Date: 2017-06-13
CPC Classifications: C25D,H01L,H05K,Y10T

Claim:
1. A method of forming a non-metallic coating on a surface of a metallic or semi-metallic substrate comprising the steps of, positioning the substrate in an electrolysis chamber containing an aqueous electrolyte, the aqueous electrolyte being an alkaline solution, and an electrode, at least the surface of the substrate and a portion of the electrode contacting the aqueous electrolyte, and electrically biasing the substrate with respect to the electrode by applying a sequence of voltage pulses of alternating polarity for a predetermined period of time, positive voltage pulses anodically biasing the substrate with respect to the electrode and negative voltage pulses cathodically biasing the substrate with respect to the electrode, in which the voltage pulses have a pulse repetition frequency of between 0.1 and 20 KHz, and in which the amplitude of the positive voltage pulses is potentiostatically controlled, and the amplitude of the negative voltage pulses is galvanostatically controlled, in which the amplitude of each of the positive voltage pulses is constant over the predetermined period of time, and in which the amplitude of successive negative voltage pulses increases over the predetermined period of time.