Mechanism of passive layer formation on AA2024-T3 from alkaline lithium carbonate solutions in the presence of sodium chloride

This study focuses on the elucidation of the formation mechanism of passive layers on AA2024-T3 during the exposure to alkaline lithium carbonate solutions in the presence of sodium chloride. Under controlled conditions, in an electrochemical cell, a protective layer was generated comprising an amorphous inner layer and a crystalline outer...

Particle induced gamma and X-ray emission spectroscopies of lithium based alloy coatings

Lithium based inhibitors in aerospace coatings are seen as excellent replacements for their chromium counterparts which are both carcinogenic and heavier. However, Li is generally difficult to detect and following changes in its distribution due to corrosion is impossible with many standard techniques. Combining MeV Particle Induced Gamma and...

Electrochemical evaluation of corrosion inhibiting layers formed in a defect from lithium-leaching organic coatings

This work presents the electrochemical evaluation of protective layers generated in a coating defect from lithium-leaching organic coatings on AA2024-T3 aluminum alloys as a function of neutral salt spray exposure time. Electrochemical impedance spectroscopy was used to study the electrochemical properties on a macroscopic scale. An...

Particle characterisation and depletion of Li₂CO₃ inhibitor in a polyurethane coating

The distribution and chemical composition of inorganic components of a corrosion-inhibiting primer based on polyurethane is determined using a range of characterisation techniques. The primer consists of a Li2CO3 inhibitor phase, along with other inorganic phases including TiO2, BaSO4 and Mg-(hydr)oxide. The characterisation techniques included...

Lithium salts as leachable corrosion inhibitors and potential replacement for hexavalent chromium in organic coatings for the protection of aluminum alloys

Lithium salts are being investigated as leachable corrosion inhibitor and potential replacement for hexavalent chromium in organic coatings. Model coatings loaded with lithium carbonate or lithium oxalate demonstrated active corrosion inhibition and the formation of a protective layer in a damaged area during neutral salt spray exposure. The...

Protective film formation on AA2024-T3 aluminum alloy by leaching of lithium carbonate from an organic coating

An investigation into corrosion inhibition properties of a primer coating containing lithium carbonate as corrosion inhibitive pigment for AA2024 aluminum alloy was conducted. It was found that, during neutral salt spray exposure, a protective film of about 0.2 to 1.5 ?m thickness formed within the area where an artificial defect was introduced...

Ultra low background cryogenic test facility for far-infrared radiation detectors

The next generation of far infrared radiation detectors is aimed to reach photon noise limited performance in space based observatories such as SPICA and BLISS. These detectors operate at loading powers of the astronomical signal of a few Attowatt (10?18 W) or less, corresponding to a sensitivity expressed in noise equivalent power as low as NEP...

Breaching Processes: A state of the art review

This report provides an overview of the state of the art with regards to embankment breach initiation and formation processes. Basic breach formation processes are explained, including a review of commonly held misconceptions. The different stages of breach initiation and formation are also explained, along with the varying needs of different...

Preprocessing of gravity gradients at the GOCE high-level processing facility

One of the products derived from the gravity field and steady-state ocean circulation explorer (GOCE) observations are the gravity gradients. These gravity gradients are provided in the gradiometer reference frame (GRF) and are calibrated in-flight using satellite shaking and star sensor data. To use these gravity gradients for application in...

Tracking and orbit determination performance of the GRAS instrument on MetOp-A

The global navigation satellite system receiver for atmospheric sounding (GRAS) on MetOp-A is the first European GPS receiver providing dual-frequency navigation and occultation measurements from a spaceborne platform on a routine basis. The receiver is based on ESA’s AGGA-2 correlator chip, which implements a high-quality tracking scheme for...

On the joint inversion of SGG and SST data from the GOCE mission

CHAMP gravity field recovery using the energy balance approach