WEAR OF CAST-BONDED COMPONENTS IN A COAL PULVERIZER MILL

An investigation has been carried out into the manufacture and field t rial of alloy white iron beater plates used to process coal in a KSG c oal pulveriser mill, The components were made by the cast bonding proc ess, which involves casting a wear layer onto a steel substrate to for m a bimetallic composite product, Four alloy white irons, containing p rimary and/or eutectic carbide volume fractions ranging from nominally 10 to 40%, were used as the cast overlay in the manufacture of the be ater plates. Two replicates of each alloy composition were tested in a mill along with two standard austenitic manganese steel plates. All b eater plates completed 3275 h of operation, with the best performing a lloys receiving an additional 3471 h of service in a second campaign. The results showed that increasing carbide volume fraction decreased t he wear rate most markedly at sites of low-angle erosion, and that it had a smaller influence at higher angles of abrasive particle attack. Subsequent scanning electron microscopy examination of worn components revealed that the primary mode of material loss at the lower carbide volume fractions was microspalling, with sub-surface fractures occurri ng within the carbide particles and along carbide-matrix interfaces. S urface microgrooves were more evident in the alloy white iron beater p lates with higher carbide volume fractions. (C) 1997 Elsevier Science S.A.