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 925oC, 950oC and 975oC, 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 975oC 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.

Key words: Carburization, surface hardness, mild steel, mussel shell, prosopisafricana seed pod