Spraying Parameters Effects on Penetration and Adhesion of Water Born Primer Ew 5005 on Anodized Aluminum
New environmental regulations in the US and EU require the reformulation and replacement of traditional solvent based and chromated corrosion inhibiting adhesive bond primers designed to promote adhesion and protect primary and secondary metal structures from corrosion. Typical sources of hexavalent chrome are surface treatment methods (etching and anodizing) as well as corrosion inhibiting primers. To be compliant, these new formulations need to be free of regulated toxic chromates and ideally help with achieving regulatory volatile organic content (VOC) targets. In conjunction with these efforts, new metal surface treatments have been developed to further reduce the use of chromate-containing products in the manufacture and maintenance of aircraft structures. The 3M™ Surface Pre-Treatment AC-130-2 and AC-131 sol-gel surface pretreatments are available from 3M and are designed to be a chromate-free solution for surface preparation and pretreatment of aluminum, nickel, and titanium alloys. The 3M™ Scotch-Weld™ Structural Adhesive Primer EW-5005 (hereafter, EW-5005) was developed to meet new stringent regulation at the same time provide compatibility with the AC 130-2 and AC 131 series sol-gel surface pretreatments as well as industry standards such as FPL(Forrest Products Laboratory) Etch and PAA(Phosphoric Acid Anodization) or CAA(Chromic Acid Anodization). The work presented in this paper studies the impact of application techniques and parameters on performance attributes of solvent based primer and water based primer EW 5005. Unlike the solvent based primer, water based primers are more impacted by application techniques and parameters. Scanning electron microscopy (SEM) in combination with mechanical and corrosion performance assessments were used in this study to evaluate spray techniques and application parameters on primer performance. Optimized application technique to the spray setting, EW-5005 demonstrates an equivalent level of corrosion inhibition and mechanical performance compared with solvent based, hexavalent chromium containing adhesive bond primers used in the industry.
Authors: Lance Chen, Michael Newman, Rick Carlson, Dmitriy Salnikov, Sheryl Kazle, Michael Mandanas, Mark Shook, Jonathan Kemling, and Joe Orrock
Conference: SAMPE Seattle 2017