Corrosion of aluminum and its alloys

Having been discovered some 180. years ago, aluminum has a relatively short history and only recently completed its first century of commercial manufacture. The key to its extensive use today is its corrosion resistance and its extreme versatility that make it suitable for a wide range of products from household foil to armor plate and the essential construction material for generations of aircraft and space vehicles. Aerospace applications, which demand strength, toughness, corrosion resistance and light weight, have provided the greatest stimulus for alloy development and corrosion research, which continues even today. ¹ Durable aluminum has provided a vast web of power transmission cables, cladding for all types of buildings and the versatile extruded section for glass house construction. It is increasingly the metal chosen for reducing the weight, thereby reducing emissions from the world's vast and rapidly expanding population of cars and trucks. Aluminum and its alloys offer a diverse range of desirable properties that can be matched precisely to the demands of each application by the appropriate choice of composition, temper and fabrication mode. Aluminum can be rolled, forged, slit and sheared and shaped by extrusion through dies of a multiplicity of shape or can be cast directly into shaped products. In addition to its low density and high corrosion resistance, its other major attributes are its high thermal and electrical conductivity, heat and light reflectivity, cryogenic compatibility, nonferromagnetic property as well as its hygienic and nontoxic qualities for food contact applications. ². Aluminum as an engineering material ranks in tonnage use only behind iron and steel, and its growth in production has been continually increasing year by year. The global tonnage shipped in 2007 was 60. Mt, of which 37. Mt was provided by primary production and 23. Mt by recycled scrap. ³ Aluminum is unique in its high level of recyclability, which can compensate for the high energy cost of its primary production. Aluminum is an essential material for modern economies and often substitutes as the preferred material for steel and plastics in automotive and building applications; copper in electricity production and transmission; magnesium, titanium, composites and plastics in aerospace and defense applications; steel, plastics and glass in packaging applications; and wood and vinyl for building and construction applications. This chapter provides a general, yet concise, account of the corrosion behavior of aluminum and its alloys with reference to their classification, processing and surface treatment. . © 2010