METHOD FOR PRODUCING ALLOY DEPOSITS AND CONTROLLING THE NANOSTRUCTURE THEREOF USING NEGATIVE CURRENT PULSING ELECTRO-DEPOSITION, AND ARTICLES INCORPORATING SUCH DEPOSITS

摘要

Bipolar (pulse reversal) current, with both positive and negative currentportions, is used to electrodeposit a nanocrystalline grain size deposit.Polarity Ratio is the ratio of the absolute value of the time integratedamplitude of negative polarity current and positive polarity current. Grainsize can be precisely controlled in alloys. The deposit exhibits superiormacroscopic quality, being relatively crack and void free. Parameters ofcurrent density, duration of pulse portions, and composition of the bath aredetermined with reference to constitutive relations showing grain size as afunction of deposit composition, and deposit composition as a function ofPolarity Ratio. The parameters can be used to select a specified grain size.Coatings can be in layers, each having an average grain size, which can varylayer to layer and also in a region in a graded fashion.