Ti2AlN MAX phase: An attractive choice for the improvement of mechanical and tribological behavior of ZrB2

Abstract

Most of the engineering ceramics, including ZrB₂, suffer from poor sinterability, which originates from their strong covalent bonding. Therefore, different additives should be added to these ceramics to improve their mechanical and physical properties. In this study, 10 wt% Ti₂AlN MAX phase was added to the ZrB₂ matrix, and the samples were sintered using the spark plasma sintering (SPS) method. The density measurement confirmed that the addition of Ti₂AlN to the ZrB₂ matrix notably enhanced densification and reduced porosity. The microstructural analysis revealed that, although a portion of the Ti₂AlN MAX phase remained in the microstructure, partial decomposition to an aluminum-based oxynitride phase had also occurred. The density measurement indicated that the incorporation of Ti₂AlN increased the relative density from 80 % to 98 %. The mechanical analysis showed the positive effect of the MAX phase on ZrB₂ performance. For example, the fracture toughness increased from 2.0 MPa.m^1/2 for ZrB₂ to 5.3 MPa.m^1/2 for ZrB₂–10 wt% Ti₂AlN sample. This behavior can be correlated to the evolution of toughening mechanisms such as crack deflection, bridging, and grain refinement. The wear tests indicated that the wear rate for the ZrB₂ sample was 3.63 × 10⁻⁴ mm³/N.m, which decreased to 3.26 × 10⁻⁴ mm³/N.m with the addition of 10 wt% Ti₂AlN. This enhancement was primarily due to the improvement in mechanical properties, particularly in fracture toughness. The wear mechanisms of the samples, before and after the Ti₂AlN addition, were also thoroughly studied.