The solid particle erosion behavior of Al18B4O33 whisker-reinforced AC4C al alloy matrix composites

Steady-state solid particle erosion of squeeze-cast AC4C Al alloy and 19.5 voL% Al18B4O33 whisker/AC4C Al composites was investigated at room temperat ure. Experiments were performed with angular silica sand having four veloci ties (55 m s(-1), 140 m s(-1), 198 m s(-1) and 243 m s(-1)) and at impact a ngle in the range 15 degrees to 90 degrees. The eroded surface and subsurfa ce were observed using scanning electron and optical microscopy. The result s indicated that erosion characteristics of the composites was affected by the particle velocity and impact angle. Steady-state rate was found to incr ease with the addition of whisker to the matrix alloy at high particle velo cities or upon increasing impact angle. High erosion rate in the whisker re inforced composites can be attributed to reduced ductility. In addition to plastic deformation, flaking, gouging and microcutting, for the composites, fragmentation and dislodgement of Al18B4O33 whisker occurred with impact o f particles. At low particle velocity and shallow impact angle, the whisker at the surface can act as protective reinforcement to resist the microcutt ing and microploughing action. The erosion resistance for the Al18B4O33/AC4 C Al composites was improved as a result of whisker addition. (C) 1998 Publ ished by Elsevier Science S.A. All rights reserved.