The impact angle dependence of erosion damage caused by solid particle impact

The dependence on the impact angle of erosion damage caused by solid particle impact was characterized on several kinds of material, as expressed by a trigonometric function of both impact angle and material hardness. Erosion tests were conducted on five metallic materials, a ceramic and a plastic material using silica sand particles (mean;particle size 325 mu m) at impact angles from 3 degrees to 90 degrees, up to an impact velocity of 130 m s (-1). The geometry of the specimen and the nozzle tip were devised in order to obtain erosion damage at shallow impact angles less than 20 degrees. The reproducibility of erosion damage obtained under these conditions was consistent with that of standard erosion tests. The detailed erosion damage at shallow impact angles made the dependence of impact angle clear. Although the amount of erosion damage commonly increased with the increase in impact velocity, it was found that the dependence of the erosion damage of metallic materials on impact angle was independent of the impact velocity within 50-130 m s(-1) in terms of the relative erosion damage normalized by that at a normal impact angle. This allowed simplification of the equation for erosion damage curves. It was recognized that the maximum erosion damage and the shape of the damage curves shifted monotonically according to the material hardness, which is considered generally to be correlated with other mechanical properties. As a result, the normalized erosion damage curves for tested materials were basically correlated with a trigonometric function in which constants and exponents depended on the impact conditions, except for the impact velocity, if the properties of the particles were fixed. Moreover, in the case of metallic materials, the values related to the hardness. This simulation probably enables an estimation of erosion damage at a given impact angle from that at the normal impact angle. (C) 1997 Elsevier Science S.A.