Tribological Approach to Investigate the Interface Properties in Metallurgical Coke

Abstract

Metallurgical coke is a brittle composite material comprising predominantly carbon derived from both reactive and inertinite coal macerals. During cokemaking, these macerals form the porous coke matrix. The interfaces between the distinct maceral derived components, known as textures in the final coke structure, are well-known to be a major source of weakness in some metallurgical cokes. In this paper, we present a novel approach which applies techniques used in tribology to investigate the strength of the interfaces as well as the wear properties of the different textural constituents in metallurgical coke, at room temperature. The wear mechanisms which occur in coke were investigated using three pilot oven cokes of different single coal origin. A range of high resolution analytical techniques, including coke petrography, optical microscopy, stereo microscopy, and scanning electron microscopy, were used to determine the wear modes. The technique has also proven to be an effective method to determine the relative strength of inerts and RMDC as well as the strength of the interface between these two textures, based on their susceptibility to different wear mechanisms. Further work is focused toward being able to predict the wear properties and relative strength of the inerts in a particular coke from their properties in the original coal(s).

Tribological Testing of Metallurgical Coke: Coefficient of Friction and Relation to Coal Properties

“…For the latter point, it was important that distinct differences in the width and depth of the tracks between cokes formed from coals with different properties were easily observed. The testing conditions differed from our previous publication as we were limited by the maximum loading capacity of the load cell available for those tests; therefore, the conditions for the earlier tests were not optimal. All experiments were performed at room temperature and in the absence of added lubricant.…”

“…The tribological wear and fracture mechanisms are linked to the different carbon forms in a coke. There are three main wear mechanisms relevant to the analysis of coke cold strength that have been observed during tribological testing of coke: adhesive wear is the transfer of material from the coke surface to the indenter; delamination wear refers to the subsurface cracks parallel to the surface; abrasive wear is a “scratching” and microcracking of the softer coke surface by the indenter. Abrasive wear becomes increasingly dominant as the tribological test progresses, as the ejected coke particles are transferred to the indenter and track surface and act as abrasion particles, causing further damage to the coke bulk surface.…”

“…Recently, a tribological approach has been developed to elucidate the nature and strength of the microtextural components in coke and the interfaces between them. 10 Our tribological testing approach uses a typical ball-on-disk test setup, in which a stationary ball indenter is under a controlled load in contact with a rotating polished block of coke. It is necessary to test polished flat (<3 μm) samples of coke, as horizontally flat surfaces are important for repeatability of the tribological testing.…”

Examining mechanisms of metallurgical coke fracture using micro-CT imaging and analysis

“…The probability that a calculated high stress point will break is dependent not only on the microstructure but also on the physical properties of the textural constituents at that point. For example, our previous fractographic [13] and tribological [25] analysis of various cokes of single coal origin has indicated that the properties of the inerts within a single coke show varying interaction strength with the RMDC. Fig.…”

Detailed Modeling of Melt Dripping in Coke Bed by DEM – SPH

“…Furthermore, volumetric destruction of coke, wear, and deformation due to solution loss make it difficult to predict in-furnace phenomena. 12) A "holistic" operation design based on a phenomenological understanding of the melt dripping in heterogeneous coke beds is strongly desired.…”