Erosion wear behaviour and model of abradable seal coating

The abradable seal coating for an aircraft turbine engine is mostly composed of metal phase, self-lubricating non-metal phase and many pores. The erosion wear resistance is one of the most important properties of the coating. The erosion wear behaviour and mechanism of several kinds of middle temperature seal coatings were investigated by a CMS-100 self-trade vacuum sand erosion machine. The results show that the relationship between the erosion mass loss and the erosion time is linear, the coatings hold a maximum erosion rate at 60degrees impact angle, and the relation between the erosion rate and the impact speed is an exponential function. The speed exponent increases with the increase of the impact angle. At 90degrees impact, the abrasive particles impinging on the coating surface produce indentations and extruded lips, and then the lips are work-hardened and fall off; and flattened metal phase grains are impacted repeatedly, loosed and debonded. At 30degrees impact, the micro-cutting, plowing and tunneling via pores and non-metal phase are involved. The model of the erosion mechanism is advanced on the basis of the above-mentioned erosion wear behaviour. (C) 2002 Elsevier Science B.V. All rights reserved.