Nanocomposite Coatings | 18 Mar 2020
Why in News
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.
Key Points
- 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.
Need for Nanocomposite Coatings:
- Several aerospace, defence, automobile, space devices need to reduce friction, wear, and tear to enhance the life of components.
- Lubricating these dynamic systems add to the cost, complexity, and weight of these systems.
- The coating could help in reducing the friction of such devices.
Advantages of the Process
- 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.
- The process is highly economical without environmental constraints.
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.
Size-Selective Electrodeposition:
- For size-selective electrodeposition, Pulse Current (PC) electrodeposition – intermittent application of current is used in place of conventional Direct Current (DC) deposition.