Abstract
This study aimed to investigate the influence of bimodal TiO2/nanoTiO2 coatings obtained in the PVD/ALD hybrid process on an Al-Si-Cu-type aluminium alloy on the physicochemical properties of the investigated materials. The reference materials were uncoated substrates and samples coated with TiO2 coatings in single PVD and ALD processes. Tests were carried out on the morphology of coatings using scanning electron microscopy (SEM) and atomic force microscopy (AFM) to determine the structure of the tested coatings and their influence on physicochemical properties. The tests of physicochemical properties were carried out using the potentiodynamic and electrochemical impedance spectroscopy methods. The analysis of corrosion products obtained during the study of physicochemical properties was performed using SEM and EDS analysis. Based on the analysis of anode polarisation curves of the tested materials and Tafel analysis, it was found that a sample demonstrated the highest corrosion resistance with a bimodal coating-type TiO2/nanoTiO2, which had the lowest value of corrosion current and the highest value of polarisation resistance. The slightest corrosion resistance was characteristic for uncovered samples. Moreover, the influence of the tested coatings on the improvement of tribological contact of the surfaces of the coated materials with the counter-specimen made of cemented carbides was demonstrated.
Highlights
For many years, multi-component aluminium alloys have been widely used, primarily in the machinery, armaments, aviation, and automotive industries
The studies published in the literature on the surface treatment of silumin show that the most promising are coatings obtained by physical vapour deposition techniques (PVD) and plasma-assisted chemical vapour deposition (PACVD)
This paper presented the results of tests of a TiO2 /nanoTiO2 coating, which was called a bimodal coating, because it consists of two layers of the same type, i.e., titanium oxide obtained in a hybrid process consisting of two separate PVD and ALD technologies
Summary
Multi-component aluminium alloys (including Al-Si-Cu alloy) have been widely used, primarily in the machinery, armaments, aviation, and automotive industries. These alloys are characterised by castability, good electrical and thermal conductivity, and giving way to strength properties. The disadvantage of these alloys is their low hardness It is associated with low abrasion resistance. In addition to PACVD, many research results concern using the latest atomic deposition technique of ALD coatings. Coatings obtained as a result of the synergy of the interaction of hybrid surface treatment with the use of PVD and ALD techniques are increasingly of particular interest [1–20]
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