The effect of pH on the corrosion protection of aluminum alloys in lithium-carbonate-containing NaCl solutions

The corrosion inhibiting effect of lithium carbonate has been studied over the pH range relevant for atmospheric corrosion conditions at the polymer/metal interface. It is demonstrated that lithium carbonate offers optimum corrosion protection under moderately alkaline conditions attributed to the formation of a protective layer identified as...

Synthesis of alkali-silica reaction (ASR) products and the role of Al and Li in mitigating ASR

Using Al-rich supplementary cementitious materials to partially replace Portland cement is a well-established empirical approach to mitigate expansion of concrete caused by alkali-silica reaction (ASR). However, the mechanisms behind it are still not completely understood. Synthesis of ASR products in the laboratory provides a unique opportunity...

Local changes in the microstructure, mechanical and electrochemical properties of friction stir welded joints from aluminium of varying grain size

The present study shows results of friction stir welded (FSW) samples after different plastic deformation routes. The welds were made of coarse-grained and ultrafine-grained commercially pure aluminium. As a plastic deformation method a new hybrid process has been chosen, which resulted in obtaining samples with different characteristics of...

Scrutinizing the importance of surface chemistry versus surface roughness for aluminium / sol-gel film adhesion

The sol-gel synthesis process is a versatile method used to produce a wide diversity of materials and is being increasingly used as a surface modification method to alter porosity, wettability, catalytic activity, biocompatibility and corrosion performance of underlying substrates. Silane sol–gel films deposited on aluminium and aluminium...

Impact damage repair decision-making for composite structures: Predicting impact damage on composite aircraft using aluminium data

There is a growth in the use of composites for the new generation of wide-body aircraft such as the Boeing 787 and Airbus A350. This shift from using aluminium as the primary material is motivated by the benefits of using composites in design, manufacturing and operations. Composites offer the aircraft manufacturer the ability to create more...

Active corrosion protection of aerospace aluminium alloys by lithium-leaching coatings

For decades, scientists and engineers are searching for a safe and environmentally friendly alternative for the toxic chromate corrosion inhibitors in active protective coatings for the protection of aerospace aluminium alloys. In this search many different compounds have been investigated as leachable corrosion inhibitor, but no alternative...

The chemical throwing power of lithium-based inhibitors from organic coatings on AA2024-T3

Chemical throwing power, being the distance over which an inhibitor is able to protect a defect effectively, is an important parameter for active protective coatings. This study investigates the chemical throwing power of lithium-based leachable corrosion inhibitors exhibiting different leaching kinetics, from coatings at different inhibitor...

On the importance of irreversibility of corrosion inhibitors for active coating protection of AA2024-T3

Inhibitor leaching, fast, effective and irreversible passivation are essential for active protective coatings to protect aluminium alloys. This study presents the comparison of the active protective properties of lithium carbonate and two organic corrosion inhibitors, benzotriazole and 2-mercaptobenzothiazole, on aluminium alloy 2024-T3 with...

Compositional study of a corrosion protective layer formed by leachable lithium salts in a coating defect on AA2024-T3 aluminium alloys

Organic primer coatings loaded with environmentally harmful Cr(VI) corrosion inhibitive pigments still play an important role in corrosion protection of aluminium alloys for the aerospace industry. A potential “green” alternative coating system has recently been developed, loaded with lithium salt corrosion inhibitors. Under exposure to...

Cr(VI)-free pre-treatments for adhesive bonding of aerospace aluminium alloys

For more than six decades, chromic acid anodizing (CAA) has been the central process in the surface pre-treatment of aluminium for adhesively bonded aircraft structures in Europe. Unfortunately, this electrolyte contains hexavalent chromium (Cr(VI)), a compound known for its toxicity and carcinogenic properties. The approaching ban on the use of...

Microstructural Changes in Brazing Sheet due to Solid-Liquid Interaction

Aluminium brazing sheet is the material of choice to produce automotive heat exchangers. Although in Dutch the official translation of aluminium brazing sheet is “aluminium hardsoldeerplaat” the English name is used in the industry. Aluminium brazing sheet is basically a sandwich material and consists of an aluminium core alloy, typically an...

Microstructure-related quality of conversion coatings on aluminium alloys, Microstructuur-gecorreleerde eigenschappen van conversielagen op aluminium legeringen