Start date and planned duration: February 2019, 36 months
- Identify coatings for potential use with mechanical fasteners, with focus on improved corrosion performance in dissimilar joints.
- Determine the mechanical and corrosion performance of suitable commercially available coatings in fastener applications.
- Generate data indicating optimum combinations of coated fasteners with dissimilar materials to minimise corrosion.
- Produce a predictive model of corrosion performance based upon analytical electrode potential measurements.
The project has two main goals: to develop new fastener coatings capable of producing corrosion-resistant joints in dissimilar materials metal-to-CFRP and steel-to-aluminium applications; and to employ electrochemical techniques and accelerated corrosion testing to characterise coating performance. Data analysis will be used to help develop a predictive corrosion performance model based on electrode potential measurements.
A state-of-the-art review will identify coatings to be applied to examples of both partially and fully-penetrating fasteners. Coatings will be applied by TWI and external suppliers. Joints will then be prepared between the dissimilar materials of interest: steel-to-aluminium and metal-to-CFRP (carbon fibre reinforced polymer). The ability of the coatings to withstand the process will be assessed.
Electrochemical measurements will then be used to identify the galvanic potential within successfully completed joints and both exposure and accelerated corrosion testing will be performed. A correlation between the results of corrosion tests and the long term performance of the joints will be sought. Data analysis will be used to develop a predictive model for long term corrosion performance based upon analytical electrode potential measurements.
Benefits to Industry
Industry will benefit from improved performance driven by the design flexibility permitted by the availability of durable mechanical fastening solutions for dissimilar materials joints. Specifically, the outcomes of this project will allow industry to: (i) improve understanding of fastener coatings for dissimilar material joining applications; (ii) select an appropriate fastener coating tailored to a specific dissimilar material combination; (iii) use a predictive model to estimate long term corrosion / environmental performance; and (iv) develop further new coatings for fasteners.
Technical Literature Review: Novel Mechanical Fastener Coatings for Corrosion Protection in Dissimilar Material Joints, Andre Oliveira
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