ARCI scientists develop friction-reducing nanocomposite coatings to increase device life

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New Delhi : A group of scientists at the International Advanced Research Centre for Powder Metallurgy & New Materials (ARCI), Hyderabad, Telangana, 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.

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 scientists have found that nickel tungsten-based coatings with impregnation of particular sized Silicon Carbide (SiC) submicron particles using an economical and straightforward pulsed electroplating or electrodeposition process can provide an excellent combination of wear and corrosion resistance with the low friction coefficient and good oil retention capacity. The coatings developed by the ARCI group reduced friction more and could withstand corrosion due to salt spray better than many similar wear-resistant coatings available in the market.

The coating could address the emerging need for coatings with low friction and wear. Nanocomposite coatings with hard particles inside a tough matrix result in the best combination of wear resistance and reduced friction. 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.

Electrodeposition also called as electroplating involves the metal parts to be immersed in an electrolyte bath solution, in this case, 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) was passed through the solution, and the resulting reaction left a deposit of Ni-W alloy on the piece being plated. During electrodeposition, a diffusion layer was formed at the cathode surface due to movement and deposition of metallic ions in solution.For size-selective electrodeposition, pulse current (PC) electrodeposition – intermittent application of current was used in place of conventional direct current (DC) deposition.