Porosity in plasma electrolytic oxide coatings

Characterization and wear- and corrosion-resistance of microarc oxidation ceramic coatings on aluminum alloy

A comparative study of tribological behavior of microarc oxidation and hard-anodized coatings

A ceramic coating on AA6082 aluminum alloy prepared by plasma electrolytic oxidation (PEO) has been studied and compared against a sulphuric acid hard-anodized coating on the same alloy. Surface morphology and microstructures of the coatings have been examined by scanning electron microscopy. X-ray diffraction is used to determine the phase composition of the coatings. The adhesion strength of the coatings has been evaluated using a scratch test method. The coating's mechanical properties such elastic modulus and hardness data have been generated using a dynamic ultra-microhardness tester. Sliding wear tests with different loading rates are performed on the coatings in order to assess their wear resistance. Test results show that the PEO treated samples exhibit significantly better mechanical properties compared to hard anodized samples. The elastic modulus and hardness of the PEO coating are 2–3 times greater than of the hard anodized coating and subsequently, an improved wear resistance of the PEO coating has been achieved. The mechanical properties of the coatings and their relations to their tribological performance are discussed.

An investigation into the mechanical and tribological properties of plasma electrolytic oxidation and hard-anodized coatings on 6082 aluminum alloy

This paper investigates the micromechanical behaviour and wear properties of coatings on a Ti–6Al–4V alloy generated using the plasma electrolytic oxidation (PEO) technique. Four different compositions of electrolyte were used: aluminate, phosphate, silicate, and mixed phosphate and silicate. The coatings' composition was characterised using X-ray diffraction and energy dispersive spectroscopy, and their morphologies were examined using SEM and optical interference profilometry. Following this, the micromechanical properties of the different coatings and the substrate alloy were examined using nanoindentation, nanoindentation scratch, nanoindentation impact, and modified grit blasting equipment. Correlations between these mechanical performance measures and observed structures are discussed. The aluminate-based coating, which contained a hard Al2TiO5 phase, was found to outperform other candidate systems and gave a performance enhancement over the bare substrate. However, it appears to be prone to delamination.

H Weiss

Papers

The sliding wear resistance and frictional characteristics of surface modified aluminium alloys under extreme pressure