# The Microstructure and Properties of Hard Anodic Oxide Coatings on 5754 Aluminium Alloy Modified with Al2O3, PTFE and CaCO3 Nanoparticles

## TL;DR

This paper explores how adding nanoparticles to anodic oxide coatings on aluminum improves their hardness and wear resistance for industrial use.

## Contribution

The study introduces a duplex process with Al2O3 nanoparticles that significantly enhances coating properties.

## Key findings

- Duplex process with Al2O3 nanoparticles achieved a microhardness of 430 HV0.05.
- Coatings showed a mass loss of 9.4 mg after the Taber abrasion test.
- SEM and TEM confirmed structural and chemical changes due to nanoparticle incorporation.

## Abstract

Hard anodic oxide coatings on aluminium have long been used to enhance surface functionality. However, increasing industrial demands are driving the need for coatings with superior hardness, wear resistance, corrosion resistance and self-lubricating properties. Due to their porous structure, anodic oxide coatings can be modified by incorporating various nanoparticles. The properties of the modified coatings depend on both the type of nanoparticles used and the method employed to incorporate them. In this study, anodic oxide coatings were produced using direct and duplex methods on a semi-industrial scale to enable process control and potential industrial implementation. The coatings were modified with hard (Al2O3) and soft (CaCO3, PTFE) nanoparticles in order to customise their functional properties. Their microstructure and chemical composition were characterised by SEM and TEM. Their microhardness, abrasion resistance and electrochemical behaviour were also evaluated. Among the tested production methods and methods for modifying nanoparticles, the duplex process incorporating Al2O3 particles proved to be the most promising. Its optimisation resulted in coatings with a microhardness of 430 HV0.05 and a mass loss of 9.4 mg after the Taber abrasion test, demonstrating the potential of this approach for industrial applications.