Improving fire retardancy of Ti alloys with a refractory ceramic barrier layer

Reliable service of indispensable titanium alloys in aeroengines is limited by the bottleneck problem of titanium fires. In this study, a tri-layer fire retardant coating with a bi-functional ceramic barrier layer is proposed to suppress titanium fire. Results show that the current coating can increase the fire retardant temperature by ≥ 300 K under droplet ignition. Thermal barrier effect of the YSZ refractory ceramic layer significantly reduces Ti alloy temperature, and oxygen barrier effect prevents active Ti from directly contacting oxygen during the entire ablation process. Therefore, the two barrier effects effectively prevent occurrence of titanium fire. In addition, dissolution of the Ni-based abradable seal coating makes burning TC4 molten droplet extinguished in a short time, thus further inhibiting titanium fire ignition. The present study provides an effective method for reliable service and titanium fire-resistant design of titanium alloys.