Low-Pressure Cold Spray Deposition of Mechanically Alloyed Brass – Al2O3 Composite Coatings: Microstructure, Mechanical Properties, and Tribological Performance

• Composite brass-Al 2 O 3 coatings were obtained by mechanically alloyed 70Cu-30Zn, wt.%) feedstock by the LPCS system. • Al 2 O 3 content impact on build-up coating by spraying brass feedstock powder. • Al 2 O 3 content affects mechanical properties and their homogeneous distribution within the coating. • Al 2 O 3 content influences coating behavior under dry sliding at different speeds. This study investigates the deposition of mechanically alloyed 70Cu-30Zn (wt.%) brass powder with varying Al 2 O 3 reinforcement content (0, 20, and 40 wt.%) using a low-pressure cold spray (LPCS) system, addressing the research gap in producing brass-based composite coatings via LPCS technology, which offers advantages in the development of dense coatings with thicknesses exceeding 170 μm. The feedstock powder and resulting coatings exhibited a two-phase structure comprising α-Cu and β′-CuZn phases, characteristic of brass alloys, which influences their overall mechanical and tribological properties. Comprehensive microstructural analysis revealed that Al 2 O 3 incorporation significantly influenced coating characteristics, reducing porosity from 1.04% in corundum-free coatings to approximately 0.20% in composite coatings, where improvement in densification was attributed to the “hammering effect” of Al 2 O 3 particles during deposition. Furthermore, an increase of the Al 2 O 3 content within the feedstock powder enhanced the coating adhesion strength from 25 to 36 MPa, while the deposition efficiency decreased from 27 to 13% accordingly. Mechanical characterization demonstrated that an increase of Al 2 O 3 content enhanced both nanohardness and microhardness, achieving improvement of 60% Vickers hardness, with Weibull analysis confirming improved mechanical homogeneity at the highest corundum concentration. Tribological evaluation under dry sliding conditions revealed that Al 2 O 3 incorporation transformed the wear mechanism from predominantly adhesive to mixed adhesive-abrasive, resulting in a 60% reduction in wear rates despite a slightly increased coefficient of friction. Higher sliding speeds of 50 mm/s further reduced wear rates through accelerated tribolayer formation. This study demonstrates that LPCS-deposited brass-Al 2 O 3 composite coatings offer enhanced mechanical properties and wear resistance suitable for industrial applications.