W. N. Garrard

Bio: W. N. Garrard is an academic researcher from Defence Science and Technology Organisation. The author has contributed to research in topics: Intergranular corrosion & Corrosion. The author has an hindex of 1, co-authored 1 publications receiving 24 citations.

Corrosion Behavior of Aluminum-Lithium Alloys

Abstract: Corrosion behavior of three aluminum-lithium (Al-Li) alloys was investigated in aerated 0.5 M sodium sulfate (Na2SO4), deaerated 3.5% sodium chloride (NaCl), and aerated 3.5% NaCl. Corrosi...

Lanthanide compounds as environmentally-friendly corrosion inhibitors of aluminium alloys : A review

Abstract: Currently, chromates are among the most common substances used as inhibitors or incorporated in anticorrosive pretreatments of aluminium alloys. However, these compounds are highly toxic and their use produces serious environmental hazards. Consequently, an intense research effort is being undertaken to replace chromates by more ecological compounds. In recent years, several authors have begun studies of the behaviour of lanthanide compounds in the corrosion protection of metallic alloys. After a brief overview of the use of chromates and their ecological alternatives in corrosion protection systems, the paper reviews progress from the literature published to date concerning the application of lanthanide compounds as corrosion inhibitors of aluminium alloys in aqueous solution. Aspects of the mechanism involved in the cathodic inhibition process by lanthanides are also dealt with. In addition, these compounds have been used to prepare chromate-free conversion coatings by full-immersion and electrochemical activation methods. Treatments proposed for these conversion coatings are discussed in detail. From the comprehensive review presented in this article, it is concluded that lanthanide compounds fulfil the basic requirements for consideration as components of more environmentally-friendly formulations: low toxicity and acceptable protective capacity. However, methods proposed up to now present various limitations that restrict their application in practice. Further research efforts are necessary to develop feasible treatments for industry.

Durability and Corrosion of Aluminium and Its Alloys: Overview, Property Space, Techniques and Developments

Abstract: Aluminium (Al) is an important structural engineering material, its usage ranking only behind ferrous alloys (Birbilis, Muster et al. 2011). The growth in usage and production of Al continues to increase (Davis 1999). The extensive use of Al lies in its strength:density ratio, toughness, and to some degree, its corrosion resistance. From a corrosion perspec‐ tive, which is most relevant to this chapter, Al has been a successful metal used in a num‐ ber of applications from commodity roles, to structural components of aircraft. A number of Al alloys can be satisfactorily deployed in environmental/atmospheric conditions in their conventional form, leaving the corrosion protection industry to focus on market needs in more demanding applications (such as those which require coating systems, for example, the aerospace industry).

On the AA2198-T851 alloy microstructure and its correlation with localized corrosion behaviour

Abstract: The corrosion behaviour of AA2198-T851 alloy has been investigated using a combination of immersion tests and different microscopy techniques. Results showed that severe localized corrosion initiated within 1 h of corrosion immersion test in 0.01 mol L−1 NaCl solution. The corrosion mechanism in this alloy is intragranular and it propagates crystallographically. The propagation occurs through grain orientation dependent bands and it can be likened to the movement of dislocation through slip planes. Corrosion rings around stable pits result from pH variations. Secondary pits form around primary pits within corrosion rings and are preceded by hydrogen evolution.

Weldability of Li-bearing aluminium alloys

Abstract: Lithium bearing aluminium alloys constitute a relatively new generation of high performance, lightweight aviation alloys that are being considered for a variety of applications requiring welded con

On the severe localized corrosion susceptibility of the AA2198-T851 alloy

Abstract: The time dependent susceptibility of AA2198-T851 Al-Cu-Li alloy to severe localized corrosion in 0.01 mol L−1 NaCl solution has been investigated by immersion and SVET tests. The results reveal that the propagation of severe localized corrosion, in the alloy, is crystallographic and it is associated with the slip bands in the individual grains of the alloy. The slip bands caused uneven precipitation of the active T1 particles. Also, oscillations in SVET current density values associated with deposition and detachment of corrosion products were observed. Furthermore, the intensity of corrosion activities increased over time for open or partially covered pits.