Surface finishing is a broad range of industrial processes that alter the surface of a manufactured item to achieve a certain property. Currently, the trend is towards surface treatments. Surface engineering techniques are generally used to develop a wide range of functional properties, including physical, chemical, electrical, electronic, magnetic, mechanical, wear-resistant and corrosion-resistant properties at the required substrate surfaces. In general, coatings are desirable, or even necessary, for a variety of reasons including economics, material conservation, unique properties, or the engineering and design flexibility which can be obtained by separating the surface properties from the bulk properties. Some of common metal surface finishing technology are electroplating, electroless nickel plating, aluminium anodizing and dying, black oxidizing of copper and steel, conversion coating and passivation, pickling, heat treatment, electropolishing etc.
Electroplating is the process of applying a metallic coating to an article by passing an electric current through an electrolyte in contact with the article, thereby forming a surface having properties or dimensions different from those of the article. Essentially any electrically conductive surface can be electroplated. Special techniques, such as coating with metallic-loaded paints or silver-reduced spray, can be used to make nonconductive surfaces, such as plastic, electrically conductive for electroplating. The metals and alloy substrates electroplated on a commercial scale are cadmium, chromium, cobalt, copper, gold, indium, iron, lead, nickel, platinum group metals, silver, tin, zinc, brass, bronze, many gold alloys, lead-tin, nickel-iron, nickel-cobalt, nickel-phosphorus, tin-nickel, tin-zinc, zinc-nickel, zinc-cobalt, and zinc-iron. Electroplated materials are generally used for a specific property or function, although there may be some overlap, e. g., a material may be electroplated for decorative use as well as for corrosion resistance.
Electropolishing is used in the pharmaceutical, electronic, food, beverage, automotive, aerospace and many other industries. Pickling is the removal of oxide layers resulting from welding and heat-treating. Pickling or chemical cleaning is the chemical cleaning of metallic surfaces in order to remove impurities, stains or scale with an acidic solution. Anodizingis an electrolytic passivation process used to increase the thickness of the natural oxide layer on the surface of metal parts.
With the growth in infrastructure, India will need huge amounts of metal. Aluminium is used in various sectors such as transportation, packaging, building/construction and electricity. Globally, automotive, packaging and construction sectors are the major end users of aluminium, while in India the power sector consumes most followed by automotive and housing sectors. The sector wise consumption break -up as follows: electrical-64 per cent, transport-18 per cent, packaging-4 per cent, industrial machinery-3 per cent, consumer durables-3 per cent, and steel sweetening, power and chemicals -11 per cent. There is no doubt that Indian infrastructure is poised for a great leap forward. The surface finishing industry will play an important role in constructing the Indian infrastructure.