Surface protection by ion plated coatings

Abstract

It is now increasingly recognised that surface coating technology offers production engineers and designers significant opportunities to optimise the use of raw materials. Due to the forecasted shortage in a number of engineering metals, such as zinc, mercury, tin … etc., surface coating technology offers the most attractive finishing process, with material conservations. Suitable bulk materials may be selected for cost or structural reasons, whilst surface coating materials are chosen to meet specific surface properties, such as wear resistance, protection against corrosion, surface thermal and electrical conductance, optical reflections and decorative features. The recent design trends towards higher speeds, minimum airplane weight and maximum load capacity, however, encourage the use of light weight titanium fasteners in airplane aluminium alloy structures. This creates a serious galvanic corrosion problem to airplane skin sheets. In the following a new surface coating technique which is recently recognised as a growth of a new technology is applied to the problem of galvanic corrosion in air frame structures. The application of aluminium coatings for the protection of airplane skin sheets and fasteners against the galvanic corrosion in local environments is investigated. Both polarisation and galvanic tests are used for the evaluation of the potential of the new surface coatings. Furthermore both sodium chloride and sulphur dioxide electrolytes are used to simulate sea water and jet exhaust environments. Electrolyte saturation with either air or nitrogen are considered to compensate for the presence and lack of oxygen at different environments. It is concluded that the strong adhesion and the extensive graded interfaces of the ion plated films are responsible for the good protection of coated metallic couples.

Citation

El‐Sherbiny, M. and Salem, F. (1981), "Surface protection by ion plated coatings", Anti-Corrosion Methods and Materials, Vol. 28 No. 11, pp. 15-18. https://doi.org/10.1108/eb007177