Development of Oxide Coating on AA2024 Aluminum Alloy via Plasma Electrolytic Oxidation (PEO) for Optimization of Adhesion with Thermoplastic Composites

• Grant number: 23/07918-5
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: January 01, 2025
• End date: December 31, 2026
• Field of knowledge: Engineering - Mechanical Engineering
• Principal Investigator: Rogério Pinto Mota
• Grantee: Rafael Resende Lucas
• Host Institution: Faculdade de Engenharia (FEG). Universidade Estadual Paulista (UNESP). Campus de Guaratinguetá. Guaratinguetá , SP, Brazil

Abstract

Plasma Electrolytic Oxidation (PEO) is an environmentally efficient process because it does not use electrolytes that are harmful to the environment and human health. It is a fast process, utilizing higher voltages than conventional chemical processes like anodizing, which results in coatings on lightweight alloys with better physical and chemical properties than those produced spontaneously. The properties of the coatings depend on working parameters such as immersion time, applied potential, current density, electrolyte chemical composition, substrate chemical composition, bath temperature, and the distance between electrodes. This project aims to apply the PEO treatment to AA2024-T3 aluminum alloy using a sodium tetraborate (Na2B4O7) electrolyte, with and without potassium hydroxide (KOH). The PEO treatment will be carried out using a pulsed direct current system, and the treatment will be conducted according to a factorial 2^3 design, with 3 parameters (time, duty cycle, and electrolyte concentration) at 2 levels (maximum and minimum). The goal is to improve the adhesion between AA2024-T3 alloy and thermoplastic composite material (polyetherimide) through different bonding processes such as oxy-fuel welding, friction, adhesive bonding, etc. Adhesion strength tests will be based on ASTM D1002:10 standards. The morphology of the generated coatings and the bonding with the composite material will be evaluated using scanning electron microscopy, coupled with energy-dispersive spectroscopy (SEM/EDS). The crystalline structure will be analyzed using X-ray diffraction spectroscopy (XRD), corrosion resistance of the samples will be assessed through potentiodynamic polarization tests in a 3.5% NaCl solution, and exposure in a 3.5% NaCl solution, according to ASTM G31 standards.