IMPACT ANGLE, PARTICLE ENERGY AND MASS-LOSS IN EROSION BY DILUTE SLURRIES

The wear depth in erosion as a function of angular location on cylindrical specimens, diameter 5 mm, has been measured using suspensions containing less than 1% by mass of SiC in diesel oil in a slurry-pot erosion tester. The test variables included particle size and nominal erosion speed. Wear depth was assessed by recording linear variable differential transformer traces of cylinder radius about the circumference of the cylinders before and after short periods of erosion, chosen to give measurable but small wear, to minimize the change in cylinder shape. Typical erosion times were from 2-20 min. Target materials were Pyrex glass, 99.8% alumina, 1020 HR steel, API P110 casing steel, OFHC copper, polymethylmethacrylate, acetal and a cloth-reinforced phenolic. A mathematical model for particle trajectories and impact velocities was used to estimate the angular location of particle impacts about the cylinder, the corresponding collision efficiencies, impact angles, normal and tangential velocities, and the kinetic energies at impact. Experimental results and the values predicted by the computer model allowed comparison of the rate of erosion with the rate of dissipation of kinetic energy of impact with impact angle and angular location about the cylinder. Analysis of wear profiles was made on the basis of the distinction due to van Riemsdijk and Bitter (1959) between deformation wear (resulting from the normal component of impact velocity) and cutting wear (related to the tangential component of impact velocity). Specific energies for material removal in erosion, for both deformation and cutting wear, are given for all materials. Values are compared with those found for surface grinding and those by Neilson and Gilchrist (1968) for gas-solid erosion.