Evaluation of abradability of porous seal materials in a single-pendulum scratch device

The abradability of porous seal materials has been evaluated using a single-pendulum scratch device. The results shows that the specific energy e (=EV) and the tangential dynamic hardness HT(=FTAT) for small incursion depth are obviously higher than those for greater incursion. The specific energy e and tangential dynamic hardness HT have been proposed as two equivalent criteria of abradability of seal materials. The abradability of porous seal materials is dependent on both mechanical properties of the materials and extent of densification. A careful balance between them is the key to a satisfactory seal material.