Influence of Irregular Al2O3 Content on Electrical Conductivity, Adhesion Strength, and Tribological Properties of Cold Sprayed Al-Al2O3 Coatings on Polyether Ether Ketone Substrate

Due to its low heat input to the temperature-sensitive substrates, cold spray (CS) is regarded as a promising coating technique for achieving polymer surface metallization. In previous studies, the performance (e.g., electrical conductivity, adhesive strength, tribological properties, etc.) of the metalized Al coatings on the polyether ether ketone (PEEK) is rather poor. Therefore, in this paper, irregular Al2O3 particles were strategically added to the feedstock in different proportions (0, 10, 20, 30, 40 wt.%) to achieve better coating performance. The influence of Al2O3 percentage on coating microstructure, microhardness, adhesion strength, electrical conductivity, and wear resistance was comprehensively investigated. The results revealed that adding an appropriate proportion of irregular Al2O3 particles to feedstock can effectively improve the electrical conductivity, adhesion strength, and wear resistance of the coating. The highest electrical conductivity (18.9 MS/m) and adhesion strength (6.4 MPa) were achieved for 20 wt.% Al2O3, and the lowest wear rate (i.e., half that of pure Al coating) was achieved for 30 wt.% Al2O3 content in the feedstock. These attributes were mainly related to enhanced cohesion between Al-Al splats, the 'anchor effect' of Al2O3 particles at the coating/substrate interface, and the excellent load-bearing capacity of Al2O3 particles, respectively.