Aluminium components for marine applications protected against corrosion by organic coating cycles with low environmental impact

Abstract

Marine propulsion systems, like sterndrive systems, must be protected from corrosion degradation. In particular, in the case of aluminium alloy parts, a protective cycle consisting in a surface pretreatment and an organic coating system are often applied. Traditionally, chromate based pretreatments are often applied on aluminium alloys in aggressive environments for the protective ability of chromate layers, together with the self-healing and adhesion promotion ability. The toxicity of chromium hexavalent is pressed to find new environmentally friendly solutions. In this paper, new results concerning different protective cycles for marine propulsion systems are presented. New surface pretreatments, including zircofluotitanates, chromium(III) treatments and silane layers, were characterised in conjunction with two different organic layers: waterborne paints and powder coatings. All the systems are free from organic solvents and toxic active pigments. By electrochemical measurements and salt spray exposure, it was possible to optimise the protective cycle with low environmental impact for the protection of aluminium components for marine propulsion systems, proving final performance comparable with the traditional systems containing chemicals with high environmental impact.

Modification, Degradation and Evaluation of a Few Organic Coatings for Some Marine Applications

“…This overview basically summarizes some of these key results obtained mainly in the past 15 years, aiming to illustrate the implications of the new findings and developments in possible marine applications. Since there have been many conferences [37][38][39], articles [40][41][42] and books [43][44][45] on the traditional coating systems for marine engineering, this review tries to look at some specific marine applications of organic coatings differently, aiming to establish a relationship between coating microstructure and marine application performance. Therefore, only a few fundamental issues that have not been reviewed before are addressed for some non-traditional marine coatings, rather than the practical behavior of traditional marine paintings or coating systems.…”

Preparation and Properties of Corrosion-Resistant Coatings From Waterborne Polyurethane Modified Epoxy Emulsion

“…Many inorganic particles that include graphene (Mittal, 2014;Kausar et al, 2016;Qiu et al, 2017;Shahabadi et al, 2017;Zhu et al, 2017), Ni-Fe(Ti,W)C nanocomposite (Khorsand et al, 2018), nano-ZnO (Dhoke and Khanna, 2009;Rasool et al, 2018), SiO 2 (Khademian et al, 2015;Wang N. et al, 2016), TiO 2 (Montesinos et al, 2015;Wang N. et al, 2016), Al (Deflorian et al, 2011), Al 2 O 3 (Chen et al, 2014), Ag (Rahman, 2017), micaceous iron oxide (Kakaei et al, 2013), and carbon nanotube (Zhuo et al, 2016) have been investigated by researchers, and the results show that the corrosion resistance of composite coatings has improved significantly.…”

The Effect of Graphene on the Protective Properties of Water-Based Epoxy Coatings on Al2024-T3

“…Few papers, however, addressed the development of graphene nanocomposites with the aim of increasing the protective properties of organic coatings against corrosion phenomena [12][13][14][15][16][17]. Reports on epoxy/graphene nanocomposite coatings are less common [14,[18][19][20]] and very few researchers described the use of a waterborne resin [15,[21][22][23][24]; however, the environmentally friendly solutions that take into account the new regulations about the emission of volatile organic compounds [25][26][27][28] are of considerable interest. As it is well known, several types of green surface treatments, or coating systems, have been investigated to decrease the aluminium corrosion rate when exposed to an aggressive environment [28][29][30][31][32][33][34][35][36].…”