Influence of Ti3AlC2 additions on CMAS corrosion resistance of porous LaMgAl11O19 abradables

Abstract

The corrosion of calcium-magnesium-aluminosilicate (CMAS) is a critical degradation mechanism for the hot sections of aircraft engines, particularly affecting abradable components where inherent defects complicate the prevention of rapid CMAS melt penetration. To address this challenge, Ti3AlC2 was incorporated into the porous LaMgAl11O19 abradables at concentrations of 5–20 wt% as both a self-healing agent and sintering aid. Annealing at 1200 °C markedly improved crack closure and pore isolation within the coating, with these effects intensifying with higher Ti3AlC2 concentrations, and resulted in the retention of excess TiO2. CMAS interaction tests conducted at 1300 °C demonstrated that only the abradables with 20 wt% Ti3AlC2 addition significantly reduced the penetration of CMAS melt. This effect is attributed to the densification of the abradables caused by self-healing, which blocks the propagation of CMAS along defect channels, and the role of TiO2 as a nucleating agent that facilitates the crystallization of CMAS and the precipitation of CaAl2Si2O8. The La/Ca ratio in the solid solutions related to LaMgAl11O19 and LaTi2Al9O19 can be used to reflect the corrosion level of platelet-like grains, where a value below 1 is likely to trigger their dissolution.