Investigation of Corrosion and Wear Resistance of Ni P X X Al2o3 Tio2 Nanocomposite Coatings

Abstract

Corrosion is an inadvertent electrochemical reaction between a metal and its environment newlinee.g. air, marine, steam, high temperatures and chemicals etc., which resu lts in degradation of newlinethe materials . This happens due to the conversion of metal into metal oxide or some other newlinecompound which are weak and brittle . Common examples of corrosion include rusting/staining newlineof iron and steel utensils/railings/other structural items, the blistering of chromium plating and newlinepaint work on cars, discharge of co lored water from domestic taps, tarnishing of silver and newlinecopper wares, seizure of nuts and bolts etc. C orrosion adversely affects those very properties of newlinemetal e.g. strength, ductility, stability etc., that are to be preserved in order for metals to be used newlineas material for constructing process equipment/machiner y. In industry, corrosion is responsible newlinenot only for weakening of metal structures and consequent premature failure of plant devices newlinebut also for pollution of process liquors and contamination/discoloration of products. The losses newlinedue to purely mechanical forces are known as wear, fretting etc. However, in some cases, newlinechemical or electrochemical attack may be accompanied by the mechanical forces leading to newlinestress corrosion cracking, corrosion -erosion, corrosion fatigue or fretting corrosion. Corrosion newlineand wear are also responsible for reducing the useful service life of machinery and newlineprocess equipments in chemical and process industry. Such shortcoming of metal affects newlinethe production through unwanted shutdowns due to sudden failures, excessive leakage of newlinechemicals/steam etc., which escalate maintenance and operating costs. In some industries e.g. newlinefood, pulp and paper, drinking water distribution systems etc, contamination of products d ue to newlinecorrosion is another disadvantage. All this enhances the production cost hence affects the world newlineeconomy. Also it makes the working environment less safe. newlineNano-composite coatings are receiving increasing attention all over the world in the last few newlineyears. Investigations