Quantifying the influences of coal fly ash on rheological and compaction behaviour of iron powder and mild steel machining chips

Abstract

The solid wastes produced by the industries are becoming an ever-alarming issue for the environment, health and economy. The metal cutting industries and the coal-fired thermal power plants produce metal chips and coal fly ash (CFA) in abundance. In contrast to traditional utilization and recycling, a new approach is conceived to fabricate metal matrix composites (MMCs) through the powder metallurgy (P/M) technique. For comparison, the commercial iron powder, CFA mixture with mild steel machining chips (MSMCs) were studied for their rheological and compaction properties. The morphology and elemental characteristics of the starting materials were explored by scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). The influence of CFA on the flowability behaviour was exhibited through the Hausner ratio and the angle of repose. At the same time, the compressibility behaviour was evaluated by Carr’s index and linear compaction equations. During analysis, it was observed that the addition of CFA to the iron powder and MSMCs enhanced their rheological behaviour significantly. It has been concluded that the CFA spherical particles with a high surface finish have acted as a lubricating medium among the irregular and non-spherical iron particles and MSMCs. Further, the inclusion of CFA (0–15wt.%) reduced the green density up to significant levels, which might be helpful to improve the specific mechanical properties of the MMCs synthesized thereof. Also, the addition of CFA to the iron powder and MSMCs reduced their ability to plastic deformation, which eventually improved the strengthening of the MMCs through the load transfer mechanism.