Context: Recently,a group of scientists at the International Advanced Research Centre for Powder Metallurgy & New Materials (ARCI), an autonomous R&D center of the Department of Science & Technology (DST) have developed a process for size-selective deposition of nanocomposite coatings which can reduce  friction of these dynamic systems.
About Nanocomposite coatings

• Nanocomposite coatings are formed by mixing two or more dissimilar materials at nanoscale to improve the physical, chemical and physicochemical properties of the new materials.
• The scientists have found that nickel tungsten-based coatings with infusion of particular sized Silicon Carbide (SiC) submicron particles using a pulsed electroplating can provide an excellent combination of wear and corrosion resistance.

Advantages of Nanocomposite coatings

• It reduced friction more and could withstand corrosion due to salt spray better than many similar wear-resistant coatings available in the market.
• Several aerospace, defence, automobile, space devices need to reduce friction, wear, and tear to enhance the life of components. The usual route taken is to lubricate these dynamic systems, which add to the cost, complexity, and weight of these systems. The coating could help in reducing the friction of such devices.
• Nanocomposite coatings with hard particles inside a tough matrix result in the best combination of wear resistance and reduced friction.
• The nanocomposite coating demonstrated excellent tribological behavior (science and engineering of interacting surfaces in relative motion, which includes principles of friction, lubrication, and wear) compared to other wear-resistant coatings.
• The coatings withstood 1000 hours of salt spray (corrosion) without degradation when compared to conventional wear-resistant coatings.
• It is highly economical without environmental constraints. The process has been patented and is ready for commercialization through the industry.
• However, the size of reinforcement particles is a critical factor in deciding the friction characteristics. Too much variation in the size of reinforcement particles in composite coating results in premature failure of the coating due to stress concentration.

About Electroplating

• Electroplating or electrodeposition is a process that employs an electrical signal provided by an external power source to reduce cations of a desired metal in solution and produce a metallic coating.
• It involves the metal parts to be immersed in an electrolyte bath solution.
• In this case, it is typically prepared by dissolving crystals of Nickel (Ni) and Tungsten (W) salts in a mix of distilled water and other additives.
• A Direct Current (DC) is passed through the solution, and the resulting reaction leaves a deposit of Ni-W alloy on the piece being plated.
• For size-selective electrodeposition, pulse current (PC) electrodeposition – intermittent application of current was used in place of conventional direct current (DC) deposition. Pulsed currents of certain amplitude and duration helped in depositing coatings of desired properties, which would not be possible with conventional DC plating.