Textural assessment of Aluminium Matrix Composites Developed from Si-Based Refractory Compounds of Selected Agro Wastes

Abstract

The current work reports on the textural assessment and mechanical property of aluminium matrix composites developed from Si-based refractory compounds of selected agro wastes (rice husk, bamboo leaf, and coconut shell ash). The reliance on importation of refractory reinforcements motivated the need for a cost effective option. To this end, agro wastes materials are highly sought after because of their high silica content inherent in their structure. The Si-based refractory compounds were synthesized via a carbothermal process in a modified environment. The specific surface area, total pore volume, pore sizes, isothermal adsorption, and desorption isotherms were used to determine the textural assessment. Aluminium matrix composites were later developed using 10 wt.% formulation. From the results, a mesoporous type of distribution was observed in all the samples under investigation (the pores sizes were between 2 to 50 nm). The N2 adsorption-desorption isotherm shows the type IV nomenclature. This was also validated by the hysteresis loop showing a type H4 configuration. The BET surface area was at optimum for coconut shell ash (CCT) amounting to 293.754 m²/g, while the least surface area showed a value of 26.49 m²/g for rice husk (A1). An increase in microhardness value was observed in sample A1 (63.12 HV0.1) and a similar trend was noticed in sample B1, though with a reduction in hardness value having 6.73 % when compared with A1. The presence of silica polytypes partly appearing as cristobalite phase (a softer materials) might have led to the reduction in hardness value, as observed in BL2.  Thus impeding the hardness level, hence having the least hardness value of 47.54 HV0.1. The findings showed that variations in the hardness values is due to the different elastic behaviour of the reinforcement and the matrix