Wear characteristics of normal compressive crushing rings

Abstract

This thesis examines the wear characteristics of a promising new rock-crushing technology. This novel method employs a normal compressive force to comminute rocks between two rotating rings. To further understand the wear mechanism of these rings and the ring materials response to this type of wear, a variety of ring materials, including Hardox600, two types of sintered Tungsten Carbide (WC)/Cobalt (Co) matrix, identified as X1 and X2 - where X1 has less WC compared to X2 was used. This range of materials enabled a comparative study of wear patterns under the same operating conditions. The thesis was carried out through a set of surface studies using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), and Backscatter Electron (BE) imaging. These tools were used to closely examine the worn features on the surfaces of the tested materials. These detailed methods provided a clear view of wear patterns, enabling a better understanding of how the ring materials behave during rock crushing. After a comprehensive analysis of the crushing principle and surface wear, the high stress three-body abrasive wear was identified as the primary wear mode for this application. In response to this type of wear, the tested materials displayed contrasting material removal mechanisms. Hardox600, being the softest of the materials, primarily experienced cutting (Ploughing) and repeated plastic deformations, evidenced by slivers on the worn surface. Conversely, the sintered WC materials exhibited completely different post-wear surface topography. For these materials, most material removal was due to WC particle breakage and subsequent dislodging from the matrix. Of the two sintered materials tested, the one with a higher WC content percentage demonstrated superior wear resistance, underscoring the significance of hardness in relation to the hardness of the abrasives. The superior wear can also be explained by the smaller and more uniform WC used in the Sintered X2 compared to X1. Based on the wear resistance and hardness of the evaluated materials, we conclude that for optimal wear resistance in this wear application, materials should resist plastic deformation, as it leads to severe wear. To control wear, materials should have a hardness that is on par with that of the abrasives to minimize the severity of wear.