Corrosion mitigation of aerospace alloys using rare earth diphenyl phosphates

The corrosion protection of aluminium alloys is of high importance, particularly in the aerospace industry. The most widely used technologies utilise Chromium(VI) compounds for conversion coatings and primer additives in paint systems to provide corrosion protection to these alloys. These compounds are highly toxic, carcinogenic and detrimental to the environment, therefore the identification of alternative systems that are safe and environmentally benign, that meet or exceed the current levels of corrosion protection is vital. This research program examines the corrosion inhibition effectiveness of selected rare earth diphenyl phosphates (RE(dpp)3). These compounds incorporate known inhibitor species, namely rare earth metals, organics and phosphates into a single complex, with the aim of achieving synergistic inhibition in corrosive environments. A screening study utilising immersion and weight loss experiments identified Cerium diphenyl phosphate (Ce(dpp)3) and Mischmetal diphenyl phosphate (Mm(dpp)3) as the most effective inhibitors of corrosion for AA2024-T3. The inhibiting efficiency, mechanism of inhibition and surface interaction of these complexes on aluminium alloy AA2024-T3 was characterised using a range of electrochemical and surface techniques. A similar study was carried out using AA7075-T6 to assess the adaptability of the RE(dpp)3 compounds to protect different alloy compositions. The complexes were effective in significantly reducing the corrosion rate of the alloys, with both the cathodic and anodic corrosion processes being suppressed. This mixed inhibition was not attained with the constituent rare earth and diphenyl phosphate ions individually, indicating the need for the complex to remain intact in solution to achieve the high level of corrosion protection observed. The initiation and propagation of surface pits was effectively suppressed by the RE(dpp)3 complexes. The combination of electrochemical and surface characterisation techniques has for the first time allowed insights into the mechanism of action of these compounds on aluminium alloys, and indicated deposition was initiated at electrochemically active intermetallic particles. The mixed rare earth phases present in Mm(dpp)3 produced a synergistic effect, providing a greater degree of corrosion protection compared with Ce(dpp)3, particularly on AA2024-T3. In the final phase of this research project the RE(dpp)3 inhibitor compounds were incorporated into an epoxy coating system, and demonstrated that the initiation of filiform corrosion on AA2024-T3 could be reduced by up to a factor of 3 by their addition. The growth rate of filaments was also impeded

Corrosion protection of AA2024-T3 using rare earth diphenyl phosphates

Existing corrosion protection technologies for aluminium alloys utilising chromates are environmentally damaging and extremely toxic. This paper presents a preliminary investigation into rare earth diphenyl phosphates as new environmentally benign corrosion inhibitors. Full immersion weight loss experiments, cyclic potentiodynamic polarisation measurements and Raman spectroscopy were used in this study. Results show cerium diphenyl phosphate (Ce(dpp)3) acts as a cathodic inhibitor, decreasing cathodic current density and Ecorr by passivating cathodic intermetallic particles on the alloy surface. Mischmetal diphenyl phosphate (Mm(dpp)3) acts a mixed inhibitor, shifting Ecorr to more noble values, decreasing cathodic current density, increasing the breakdown potential and suppressing pitting.<br /

Corrosion inhibition of 7000 series aluminium alloys with cerium diphenyl phosphate

Cerium diphenyl phosphate (Ce(dpp)3) has previously been shown to be a strong corrosion inhibitor for aluminium-copper magnesium alloy AA2024-T3 and AA7075 in chloride solutions. Surface characterisation including SEM and ToF-SIMS coupled with electrochemical impedance spectroscopy (EIS) measurements are used to propose a mechanism of corrosion inhibition which appears to involve the formation of a complex oxide film of aluminium and cerium also incorporating the organophosphate component. The formation of a thin complex film consisting of hydrolysis products of the Ce(dpp)3 compound and aluminium oxide is proposed to lead to the observed inhibition. SEM analysis shows that some intermetallics favour the creation of thicker deposits predominantly containing cerium oxide compounds.<br /

A pilot test of the GoWoman weight management intervention for women with mobility impairments in the online virtual world of Second Life^®

<p><b>Objective:</b> Pilot test GoWoman, a small-group weight management intervention for mobility impaired women that was a disability- and gender-responsive adaptation of the Diabetes Prevention Program delivered in the online virtual world of Second Life^®. Objectives were to (1) examine pre-/post-intervention differences in weight, waist circumference, diet, physical activity, self-efficacy for diet and physical activity, nutrition knowledge and social support for weight management, (2) determine intervention feasibility (fidelity, attrition, engagement, acceptability).</p> <p><b>Design:</b> Single-group modified interrupted time series quasi-experimental design whereby participants served as their own controls.</p> <p><b>Results:</b> Thirteen women attended ≥8 of 16 GoWoman weekly sessions and lost an average of 5.97 pounds (2.71 kg) (3.31%) body weight (Cohen’s <i>d</i> = 0.74) and 1.44 inches (3.66 cm) (3.58%) waist circumference (Cohen’s <i>d</i> = 0.83). There were significant improvements in physical activity, diet and self-efficacy for diet and physical activity. All benchmarks for feasibility were met. Ratings of intervention content, group interactions and support and virtual world experiences were highly positive.</p> <p><b>Conclusion:</b> Findings suggest that a disability- and gender-responsive weight management intervention with peer group support delivered in an online virtual world is feasible, meaningful and may assist with weight management for mobility impaired women.Implications for Rehabilitation</p><p>This study addresses a gap in the general and rehabilitation research literature by addressing the disproportionately high rates of obesity among women with mobility impairments, who are generally excluded from tests of weight management interventions if they have limited ability to engage in vigorous physical activity.</p><p>The GoWoman program is an adaptation of the Diabetes Prevention Program Lifestyle Change curriculum that is tailored to meet the unique weight management needs of women with mobility impairments, and was created to become a publicly available, disability- and gender-responsive intervention that can be used in community and rehabilitation settings.</p><p>More rehabilitation and health promotion program should be offered in the free, online, virtual world of Second Life^® since participants in this pilot study offered many favorable comments about the new learning and social opportunities available to them there and they did not have to deal with the disability-related environmental and health challenges that often prevent them from participating in face-to-face workshops.</p><p>Preliminary indications of improvements in body weight, waist circumference, diet and physical activity after attending the GoWoman weight management intervention offered in Second Life^® tell us that these strategies are feasible for helping women with mobility impairments manage their weight and should undergo further testing.</p><p></p> <p>This study addresses a gap in the general and rehabilitation research literature by addressing the disproportionately high rates of obesity among women with mobility impairments, who are generally excluded from tests of weight management interventions if they have limited ability to engage in vigorous physical activity.</p> <p>The GoWoman program is an adaptation of the Diabetes Prevention Program Lifestyle Change curriculum that is tailored to meet the unique weight management needs of women with mobility impairments, and was created to become a publicly available, disability- and gender-responsive intervention that can be used in community and rehabilitation settings.</p> <p>More rehabilitation and health promotion program should be offered in the free, online, virtual world of Second Life^® since participants in this pilot study offered many favorable comments about the new learning and social opportunities available to them there and they did not have to deal with the disability-related environmental and health challenges that often prevent them from participating in face-to-face workshops.</p> <p>Preliminary indications of improvements in body weight, waist circumference, diet and physical activity after attending the GoWoman weight management intervention offered in Second Life^® tell us that these strategies are feasible for helping women with mobility impairments manage their weight and should undergo further testing.</p