Investigation of the microstructure, corrosion resistance and hardness of bone particle reinforced cast iron for engine blocks application in automotive and marine industries

Abstract

This paper aims to examine the microstructure, corrosion resistance and hardness of bone particles reinforced cast iron for advanced applications in marine and automotive industries, especially for the fabrication of engine blocks. In most marine and automobile industries, cast irons remain the major material used for the manufacture of engine components such as flywheels, piston rings, cylinder heads and engine blocks. Nevertheless, several categories of cast iron possess poor impact strength, low corrosion resistance, easy crack propagation and brittle failure over time. As a result of these challenges, cast iron scraps melted and reinforced with particles from goat bone. Samples of reinforced and unreinforced cast iron were produced. The microstructure of the samples was studied using SEM/EDS (scanning electron microscope equipped with energy dispersive spectroscope) and XRD (X-ray diffractometer), while the corrosion rate of the samples was studied using potentiodynamic polarization technique following ASTM G102 standard and using 3.65% NaCl solution as the corrosive medium. The SEM micrographs indicated that the goat bone particle (GBP) reinforced cast iron possessed more refined microstructure, smoother morphology and microstructural homogeneity. For the unreinforced cast iron sample (control), the corrosion rate (Cr) and Brinell hardness of 1.427 ​mm year−1 and 275.3 HBN, respectively. On the other hand, the goat bone particle (GBP) reinforced cast iron samples possessed a Cr and hardness ranging from 0.510 to 1.006 ​mm year−1 and 288.9–297.4 HBN, respectively. These results indicated that the goat particle reinforced cast iron sample (control) possessed higher passivation and superior indentation resistance relative to the unreinforced cast iron sample.