Calcium carbonate obtained from mussel shell waste: A novel energizer in the carburization of mild steel

Abstract

The rising cost of the conventional energizers couple with the effect of the residue may have on the environment, waste materials  especially those that are widely reported to possess carbonate and are eco-friendly are gradually attracting attention globally. This paper  therefore, presents the opportunity of using mussel shell waste as an alternative energizer to the conventional energizers in the pack  carburization of mild steel. The carburization treatment was carried out at the austenitic temperature of 925^oC, 950^oC and 975^oC, and  holding time of 1, 2 and 3 hours respectively. Thereafter, the test samples were quenched in water to obtain a hardened martensitic steel  surface. Standard method was adopted to determine the surface hardness of the carburized and un-carburized steel samples. Micro- structural examination was also performed using standard metallographic techniques to observe the microstructure formed. The results  showed a progressive increase in the surface hardness of the carburized steels as the temperature and holding time was increased for all  the steel samples carburized with and without the energizer. However, the steel samples carburized with prosopisafricana seed pod  and mussel shell waste mixture exhibited higher surface hardness compared to those carburized with prosopisafricana seed pod waste  alone. The maximum surface hardness values of 452.8 VHN, 503.5 VHN and 581.3 VHN were obtained at the carburizing temperature of 925^oC, 950^oC, and 975^oC respectively, for 3 hours holding time with the steel samples carburized with prosopisafricana seed pod and  mussel shell waste mixture. The control sample gave a surface hardness value of 122.3 VHN. The results of the study have shown that the  calcium carbonate from mussel shell waste acted as an effective energizer and would provide good economics in the carburization of  mild steel.