Part 1: Design and development of new sustainable coatings applied on aluminium 6061 alloy-RRA heat treated for engineering applications

• Published in: Surface & coatings technology 2017-11, Vol.328, p.488-498
• Main Authors: Mayén, Jan, Abúndez, Arturo, Porcayo-Calderón, Jesús, Pereyra, Isa, Serna, Sergio, Puente-Lee, Iván, Salinas-Bravo, Victor Manuel, Torres-Islas, Álvaro
• Format: Article
• Language: English
• Subjects: Ageing; Al 6061 alloy; Aluminum alloys; Aluminum base alloys; Coated electrodes; Corrosion behavior; Corrosion prevention; Corrosion rate; Corrosion resistance; Corrosion tests; Corrosive wear; Diamond-like carbon films; DLC-coatings; Electrodeposition; Electrolytes; Electron microscopy; Heat treating; Heat treatment; Polarization; Protective coatings; Reageing; Regression analysis; Retrogression; Robust regression; Scanning electron microscopy; Series & special reports; Sugarcane; Sustainable development
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2017.09.012

In this work, an aluminium 6061 alloy was subjected to a designed retrogression and reageing (RRA) heat treatment, and also coated with diamond-like carbon (DLC) interphase film by electrodeposition, in order to assess the corrosion protection by potentiodynamic polarization testing when the samples are exposed to a simulated sea environment. The electrodeposition was performed using three sustainable electrolytes: a) 5% CH3COOH electrolyte obtained from sugar cane juice, b) an electrolyte with CH3COOH (obtained from sugar cane juice)+C4H6O6+C6H8O7+NaHCO3 and c) a 5% CH3COOH electrolyte for anodizing and DLC deposition. Scanning electron microscopy was performed on the coated samples before the corrosion tests in order to relate polarization resistance (Rp) to the coating microstructural features. The correlation between Rp, corrosion rate (C.R.) and mechanical strength (UTS) to the heat treatments, performed on the coated Al 6061 alloy, was established by a multivariate regression analysis, which allows to find the best combination of the heat treatments and electrodeposition electrolytes for further composite coatings design and development. The electrochemical testing on the electrodeposited films showed that the polarization resistance was greatly increased, from an initial value for the Al 6061-T6 of 126 up to 17,300Ωcm2 for the coated conditions, which implies a reduction of the corrosion wear about 99.29%. •Sustainable DLC films electrodeposited using CH3COOH were developed on aluminium 6061 alloys for corrosion protection•The corrosion wear was reduced 99.29% when compared to the uncoated aluminium surface•The applied heat treatments and the carbon content deposited on the Al-6061 has a significant impact on corrosion properties•Empirical equations were developed to design required heat treatments and DLC films with specific anticorrosion properties