Wear mechanisms of hard phase containing materials

Abstract

AbstractWear affects the service life of tools and counteracts an economic operation of a tunneling project. Because of wear, tools must be replaced to ensure adequate penetration, which means downtime. Targeted planning of replacement intervals requires knowledge of precise wear prediction models. In these predictive models the abrasiveness of the soil has to be regarded, which can be evaluated by experimental experiments such as the LCPC test for soil and the CAI test for solid rock. However, the forecast models developed provide only a rough guide value and often do not correlate with the real wear conditions of the tools during a tunneling project. The main reason here is to mention the disadvantage that in the previous work not the overall tribological system has been considered sufficiently. Thus, the wear occurring on the tool is not only dependent on the abrasiveness of the soil to be penetrated, but is also determined by the material properties of the tool, the loads acting on it and the presence of any intermediate and surrounding media. From this simple consideration, it can be seen that wear is not a sole property of the soil or of the tool material, but a system property. The motivation of this short report is to show the basics of tool wear of tools used for tunneling applications as well as to show basic boundary conditions for future experimental work and simulations in the field of tool wear. First, the tribological system and the four main wear mechanisms will be presented. In a further step, the damage mechanisms are focused on the dominant wear mechanisms abrasion and surface disruption of tunneling tools. Thereby, interaction of abrasive particles or crack propagation in hard phase materials at the microstructure level will be discussed.