Corrosion Prevention in Automobile Bodies

Abstract

The prevention of corrosion in car bodies has reached a high degree of excellence, or still leaves much to be desired, according to the point of view adopted. The organic finishing of the main part of car bodywork, utilizing heavy undercoats and durable top-coats on steel often prepared by phosphating, has reached a very satisfactory degree of excellence on flat or nearly flat surfaces. Difficulties still arise at edges, corners, crevices and re-entrants. These are discussed in relation to general principles of design and of testing. The finishing of trim is in a more fluid condition. Nickel/chromium plating of steel, zinc-base alloys and brass has long been the general bright finish adopted. The relative advantages and disadvantages of such trim and that made from bright anodized aluminium and from stainless steel are discussed. Newer finishes such as electrodeposited nickel-tin alloy coatings are also considered. Temporary corrosion prevention, such as can be applied to finished bodies for the period after manufacture but before service, is described. The contribution to corrosion prevention that can and should be made by the user is outlined. Storage methods vary widely, but are a very important factor in the life of a car. Cleaning and polishing methods are discussed. The general principles of corrosion testing appropriate to car bodies are considered, in the light of the very varied corrosive environments that are experienced in service.