Synergistic reinforcement mechanisms of Cu/graphite composites with MAX phase Ti2AlN and ZrO2-B4C ceramics: Enhancements in mechanical, thermal, and tribological properties
In braking materials field, MAX phase has been introduced into Cu-based composite materials to address issues such as inadequate wetting between ceramic particles and the metal matrix. This study focuses on preparing Ti 2 AlN-ZrO 2 -B 4 C reinforced Cu-based materials via the powder metallurgy method, and investigates the effects and mechanisms of different Ti 2 AlN/ZrO 2 ratios on the mechanical, thermal, and tribological properties of these materials. The addition of an appropriate amount of Ti 2 AlN (3 wt%) can enhance the densification and mechanical properties of Cu-based materials, as the diffusion of Al atoms promotes the sintering process. Similarly, the diffusion of Al also improves the thermal conductivity at grain boundaries, resulting in samples with higher Ti 2 AlN content exhibiting superior thermal diffusivity. When the Ti 2 AlN content reached 7 wt%, the material exhibited optimal hardness (43.35 ± 1.05 HBW), moderate shear strength (19.84 ± 1.86 MPa), as well as excellent high initial braking speed friction coefficient and stability. The reinforcement primarily arises from the diffusion bonding between Ti 2 AlN and Cu, leading to the formation of Cu-Ti compounds at the interface, which facilitates Ti 2 AlN in providing frictional force during the friction process and promotes the formation of a friction film due to the “pinning effect”. Additionally, the layered structure of Ti 2 AlN and the subsequent formation of amorphous Al 2 O 3 after oxidation contributed to the enhancement of friction stability.
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