ON THE IMPACT RATE AND IMPACT ENERGY OF PARTICLES IN A SLURRY POT EROSION TESTER

Short-time erosion tests were conducted with dilute water and water-glycerin suspensions of glass beads to determine the rate of particle impact and the dimensions of impact craters using annealed and electropolished OFHC copper rod specimens. Particle diameters were 75-90, 212-250, 500-600 and 750-mu-m, nominal rotation speeds of the erosion targets in the pot were 9.35 and 18.7 m s-1 and the carrier liquid viscosity was in the range (0.66-60) x 10(-3) N s m-2, (0.66-60 cp). The work done in forming a crater of specified diameter was determined for each particle size by indentation using a single glass bead mounted on a microhardness tester. Using the assumption that all the kinetic energy of an impacting bead was dissipated in plastic work, the impact velocities of particles forming craters were calculated for most test conditions. The collision efficiency for the specimen was determined for most test conditions and was found to decrease with decreasing nominal velocity, increasing carrier liquid viscosity and decreasing particle size. The erosion rate, expressed as either material lost per unit area per unit mass of impacting particles or material lost per unit area per unit time, was estimated and shown to be strongly affected by the flow conditions for individual particles.