Nanostructured surface preparations by electrochemical techniques

Electrochemical techniques involving either cathodic or anodic processes have been utilized for preparation/modifications of surfaces for decades. Since 1990's followed by growing interest on nanomaterials research, special attention has been put in engineering the surfaces in nano-scale dimensions. Starting from zero-dimension (0-D) (like nano-dots) to three-dimension (3-D) nanostructured surfaces (i.e. nanocrystalline, nanocomposite deposits or anodically modified bio-implants surfaces) have been successfully prepared by employing suitable electrochemical techniques. Such electrochemical techniques range from traditional DC, galvanic displacement/corrosion to modern pulse techniques (two or multi-pulse with single polarity or bipolar), chronopotentiometry, chronoamperometry and electrochemical quartz crystal microbalance etc are important for growth and stabilization of nanostructured functional surface. In this presentation, an overview of utilization of various electrochemical techniques in combination with electrochemical parameters for growth of different dimensional nanostructured surfaces will be discussed. For example, growth of various nanocrystalline/nanocomposite coatings (3-D) with superior functional properties by DC as well as pulse electrolysis has now been well adopted worldwide for industrial production. In fact, electrodeposited nanocrystalline Ni is now being used for in-situ steam generator repair in PWR and CANDU reactors. Growth of such 3-D nanostructured surfaces by electrochemical dissolution has also got technological attention for biomedical implants. Besides these, growth of metallic multilayer (2-D nanostructure) films employing pulse electrolysis has already shown promising 9% GMR (Co/Cu multilayer) at RT and superior tribological performances for Ni/Cu multilayer compared to individual elements in BARC. This talk will further address basics of growth of the one-dimensional (nano-rod or nano-tube) and zero-dimensional (nano-dot) surfaces based on various electrochemical growth techniques. (author)