Laser-Interference Surface Preparation for Enhanced Coating Adhesion and Adhesive Joining of Multi-Materials (Final Project Report)

Technical Report · Wed Sep 01 04:00:00 EDT 2021

DOI:https://doi.org/10.2172/1826028· OSTI ID:1826028

Sabau, Adrian S. ^[1]; Meyer, III, Harry ^[1]; Jun, Jiheon ^[1]; Li, Jianlin ^[1]; Leonard, Donovan ^[1]

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1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

This report investigates a laser-interference surface treatment as a non-contact, i.e., without major solid/liquid medium application or abrasion, and non-chemical surface preparation method for aerospace coating systems. It was proposed to use the laser-interference technique to structure surfaces of Al and/or Ti, creating "rough" surfaces with pre-engineered series of ridges and valleys at submicron scale. The science goal of this study was to develop an understanding of the surface microstructure, topology, and physical mechanisms that would improve adhesion and corrosion protection of Al2024-T3. Microstructure analysis indicates that the laser-interference structuring (LIS) was found to reduce the formation of CuMn-rich precipitates in Al 2024-T3 over a 500-800 nm depth from top surface. The X-cut and cross-hatch coating adhesion ratings indicate that the LIS specimens meet the performance requirements in the coating adhesion specifications by having a higher or identical ranking to those specimens prepared with current state-of-the-art chemical conversion or sulfuric acid anodizing. After the ASTM B117 corrosion exposure, it was found that the laser processed specimens exhibited only few blisters. It was found that the corrosion damage was minimized at a laser rastering speed of 4 mm/s, for which only 33% of specimens developed very minor corrosion damage. The ASTM D1654 creepage ratings, used to evaluate corrosion damage along the scribe lines, were found to be at least nine for all coated panels. These results indicate that the laser-interference technique with the additional acetone wiping has the potential to be further developed as a minor chemical surface preparation technique for chromate-containing epoxy primers coatings.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA); USDOD; USEPA
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1826028
• Report Number(s): ORNL/SPR-2021/2257; WP-2743
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
aluminum
coating adhesion
corrosion
dissolution
interference
laser
microstructure
precipitates
primers
surface treatment