Metallic Structures with Variable Properties

Abstract

Variable property deposit, at least partially of fine-grained metallic material, optionally containing solid particulates dispersed therein, is disclosed. The electrodeposition conditions in a single plating cell are suitably adjusted to once or repeatedly vary at least one property in the deposit direction. In one embodiment denoted multidimension grading, property variation along the length and / or width of the deposit is also provided. Variable property metallic material deposits containing at least in part a fine-grained microstructure and variable property in the deposit direction and optionally multidimensionally, provide superior overall mechanical properties compared to monolithic fine-grained (average grain size: >20 micron) or entirely amorphous metallic material deposits.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This is a continuation-in-part of U.S. patent application Ser. No. 12 / 003,224, filed Dec. 20, 2007.TECHNICAL FIELD[0002]The invention is directed to the direct current (DC) or pulsed electrodeposition of a metallic material to provide a variable property product containing, at least in part, a fine-grained metallic material with an average grain-size between 2 and 10,000 nm.BACKGROUND OF THE INVENTION[0003]Modern lightweight and durable articles require a variety of physical properties which are oftentimes not achievable with a monolithic material synthesis approach. Materials with variable properties, that is variation in a property among levels or layers, throughout the depth of the article, are described in prior art. These include parts with graded properties (such that the distinct levels or layers exhibit differing porosities, chemical compositions, grain sizes, filler amounts and / or hardness values), that is having in different lev...

AI Technical Summary

Benefits of technology

[0011]Coatings or layers of varying properties improve durability by minimizing surfaces and interfaces of dissimilar materials which are prone to failure. In the case of the varying the microstructure such as the grain size, grading enables the transition from a softer, tougher core to a hard, wear resistant outer surface.

[0013]Of special interest is that the variable property deposit is prepared in a single plating tank. In the past, layered structures of different composition but with uniform properties in the layer were obtained by using several plating tanks each containing a dedicated electrolyte and without varying the plating conditions. The workpiece was simply moved from one tank to the next, with repetitive washing steps in between, to effect the property change The disadvantage of this approach is increased floor space, increased capital equipment and increased processing cost due to the cost of water purification and disposal for the wash water. An added cost / risk is cross contamination particularly with complex parts which may form cups etc. entrapping electrolyte which cannot be easily removed by washing steps significantly increasing the bath maintenance and overall operating cost.

Problems solved by technology

This method is limited in its practical utility insofar as deleterious impurity contamination is frequently unavoidable, component shape flexibility is limited, the process is energy intensive, and is not readily scalable.

This method has the disadvantages that it is not applicable to pure metals, i.e., is only applicable to alloys, and that it is dependent for grading on changing Polarity Ratio, a parameter that is not directly supplied to the system.

The employment of reverse (anodic) pulses requires expensive power supplies and results in a significantly reduced plating efficiency as metal dissolution occurs during the reverse pulses.

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