Erosion of a high-carbon steel in coal and bottom-ash slurries

This paper discusses the observations made during erosive wear testing of a high-carbon steel (0.65% C) in coal and bottom-ash slurries. The slurry wa s made by separately dispersing 30% coal and bottom ash (collected from a t hermal power plant) in tap water. The tests were performed using a sample r otation method in the slurry at a fixed linear velocity of 5 m/s for differ ent traversal distances at room temperature. To see the influence of micros tructural features on slurry wear response, the steel was subjected to hard ening and annealing heat treatments. Test results indicate that material loss of the specimens increased with tr aversal distance in all cases. Further, the hardened steel showed a lower r ate of material loss when compared with steel in an annealed condition in e ither of the test environments. Moreover, irrespective of heat-treatment co nditions, the samples revealed significantly higher material loss when test ed in the bottom-ash slurry than in the coal slurry, The higher rate of mat erial removal in the case of the former was attributed to the more efficien t transfer of the kinetic energy of the moving (hard) bottom-ash particles to the specimen surface than in the case of the softer coal particles. Frac ture of coal particles as a result of impact during the course of slurry er osion further supported the view. Results have been explained on the basis of the characteristics of the affe cted surfaces and changes in the morphology of the erodent particles after the test.