Metal finishing chemicals are used widely across various end-use industries such as electrical & electronics, automobile, aerospace & defense, and many others. Automotive is the leading metal finishing chemicals end-user. Metal finishing chemicals help to protect automotive parts from corrosion and chemical reactions, such as the engine, shock absorbers, gears, body, rim, cylinder, and radiator.
Metal finishers use a variety of products and methods to clean and plate metallic and non-metallic surfaces, to produce a work piece with the required surface characteristics. Usually in the industry, electrolytic plating, electroless plating and methods of chemical and electrochemical processing are used. Degreasing, cleaning, pickling, etching, and/or polishing may be common supporting procedures. A few of the materials used in metal finishing are cleaning solvents and surfactants, acids and etching bases, and metal salt solutions for placing the finish on the substrate.
Types of Metal Finishing Processes
Through passing an electrical current through a solution consisting of dissolved metal ions and the metal object to be plated, electroplating can be accomplished. The metal object, while attracting ions from the solution, acts as the cathode in an electrochemical cell. Ferrous & non-ferrous metal objects are plated with various metals namely brass, aluminum, cadmium, copper, bronze, chromium, iron, gold, lead, nickel, silver, tin, platinum, and zinc.
The process is regulated by monitoring a number of parameters such as temperature, residence time, voltage and amperage, and bath solutions purity. Plating baths are mostly aqueous solutions, so it is possible to electrodeposit only those metals which can be lowered in aqueous salt solutions. Aluminum, which can be plated from organic electrolytes, is the only exception to this principle.
Electroless Plating and Immersion Plating
Electroless plating is the chemical deposition of a metal surface on an object by using chemical reactions instead of electricity. A source metal (generally a salt), a reducer, a complexing agent for keeping the metal in the solution, and numerous buffers and other chemicals designed to maintain both stability and improve bath life are the key ingredients that are requisites of an electroless plating solution. Copper and electroless nickel plating are widely used for circuit boards that are printed.
Immersion plating is a similar process because the coating is applied using a chemical reaction. The difference, nevertheless, is that the reaction is caused not by adding two chemicals into the plating bath, but by the metal substrate. Through chemical removal, typically zinc or silver, this process produces a thin metal deposit. Immersion baths are typically combinations of metal salts, alkalis, and complexing agents (e.g. salts of lactic, glycolic, or malic acids). Electroless plating and immersion plating produce more waste than other plating methods, but there are significant differences in productivity between individual facilities.
Chemical and Electrochemical Conversion
A protective and/or decorative coating on a metal surface is created by chemical and electrical conversion treatments. Chemical and electrochemical processes of processing include phosphating, chromating, anodizing, passivation and coloring of metals. The surface is primed for further treatment by phosphating. This phase precedes painting in some cases. Chromating deposits a protective film on metal surfaces using hexavalent chromium in a certain pH range.
Anodizing is an immersion process wherein the work piece is put in a solution (usually metal salts or acids) where an insoluble metal oxide is formed by a reaction. The reaction proceeds and creates a thin, non-porous layer that provides good resistance to corrosion. This method is sometimes used as a painting pretreatment. Passivating also includes immersing the work piece with sodium dichromate into an acid solution, typically nitric acid or nitric acid. The passivating process can be used to prevent corrosion and to lengthen the product’s life. Metal coloring requires chemical preparation to add a decorative finish to the work piece.
Trends in the metal finishing industry
Like most of the other industries, the most important influencers for future trends in the metal finishing industry are environmentally-responsible techniques. As a result, a change from conventional solvent-borne technologies to new technologies focused on water-borne emulsion polymers, high solid coatings, and powder coatings are taking place. Intense pressure to regulate volatile organic content of the coating materials to prevent excessive air pollution has been a significant factor in this development, especially in products used in the home or office.
Increased cost savings, as well as increased production and delivery capacity across the board in the coatings industry, have also been driven by economic factors. A further trend in the metal finishing industry is the pervasiveness of electroless nickel-plating, resulting in a decline in the market for electroplating.
Strict environmental legislation, as well as economic recession are two disincentives to the electroplating market, resulting in an upswing in the more environmentally-friendly electroless nickel-plating sector. Focusing on new technologies and developments (such as no or partial coats) would allow the customer even in the wake of economic decline to be more productive.
In recent years, the subsector of biobased chemicals has grown much faster than the sector of petrochemicals, and this is projected to continue. The global chemical industry will grow significantly over the coming years. Such a situation is one that attracts the attention of policymakers for a variety of reasons, such as the need to regulate adequately and remove barriers to development as growth is seen as beneficial to society and industry.
Surprisingly, there are huge numbers and types of chemicals that can be generated through a source of biomass and/or bioprocessing course. The list includes many platform chemicals like propane and butanediols, carboxylic acids, isoprene, short-chain olefins, and ethanol; vitamins; amino acids; polymers including alginate and xanthan gum; and extremely important industrial enzymes like additives used in washing powders.