“…The ratios of the newly formed CAC, CAO, C@O, and O-C@O peak areas were 68.1%, 5.6%, 14.1%, and 12.1% respectively. The chemical change of the Al adherend by the optimal Argon plasma treatment was confirmed, and the wettability and hydrophilicity of the Al adherend was improved by increased surface free energy caused by an increase of the types and concentrations of functional polar groups such as carbonyl (C@O) and carboxylic acid (COOH) [15,17,19]. Table 1.…”