Microstructure, wettability, cavitation and corrosion performance of aluminum (Al6061) coated with RF-sputtered AlN thin film

This study addresses the challenge of enhancing aluminum substrates with AlN coatings for improved durability. Novel RF-sputtered AlN coatings were developed, demonstrating deposition with equiaxed crystals and a predominant presence of aluminum and nitrogen. The coatings exhibited hydrophobic properties as shown by contact angle measurements. Cavitation erosion resistance was systematically analyzed, revealing optimal parameters for minimizing mass loss, including jet velocity, impingement angle, and stand-off distance, thereby showcasing the protective role of the RF-sputtered AlN coating. Response Surface Methodology (RSM) provided insights into the correlation between operational parameters and mass loss, leading to process optimization with specific mass loss values and high desirability percentages. XPS analysis of corroded AlN on Al-6061 revealed aluminum compounds, sodium, NaCl, and oxidation products, aligning with SEM/EDS results and confirming the coating's effectiveness in mitigating corrosion. Carbon and oxygen were the most abundant elements by weight and peak area. Overall, this study offers valuable insights into the multifaceted performance and protective capabilities of RF-sputtered AlN coatings.