“…Therefore, rebounding particles near the eroded surface may be regarded as shielding it, in a manner similar to debris shielding ascribed to the high-speed erosion of bodies in a rain field. 8 Moreover, experimental investigations of the brittle erosion mode have indicated that maximal surface erosion by particle-laden jets did not occur at an incidence angle of 90 deg, although .the brittle erosion by a single particle should be maximal at this angle; it has been surmised that at this angle there is considerable interference of incident particles with rebounding particles, hence, the reduced erosion. 9 In addition to the particles' incidence angle, the following parameters reportedly have increased the effect of particle concentration on the erosion rates 7 : the impact velocity, strength of the abrasive particle, and particle size.…”