Case hardening of mild steel using cowbone as energiser Paul Aondona Ihom Department of Mechanical Engineering, University of Uyo, PMB 1017, Uyo, Akwa Ibom State, Nigeria. Accepted 23 September, 2013 ABSTRACT In this study, various carburizing compounds were used to pack carburised mild steel. Various weight percentages of cow bone were used as energizer in the carburizing compounds. The experiment was carried out using a muffle furnace at 900°C for 8 h. Hardness tests were taken using Vickers micro-hardness tester. The result showed that 60 wt% charcoal / 40 wt% cowbone had the best result with an effective case depth of 2.32 mm produced on the case of the carburized steel. The work showed that cowbone can be used as energizer in pack carburization of mild steel. The hardness profile plot of the 60 wt% charcoal / 40% cowbone carburized mild steel was also higher than the other compositions. Keywords: Cowbone, energizer, case hardening, wear resistance, carbonates. E-mail: draondonaphilip@gmail.com. INTRODUCTION Pack carburization or solid carburization uses solid carburizing material as the carbonaceous source. Commercial pack carburization utilizes energizers in the case hardening of mild steel. Different types of energizers are used together with carbonaceous materials to increase the carbon potential of carburizing materials. The commonly used energizers are BaCO 3 , Na 2 CO 3 , and CaCO 3 . Over the years, the efficacy of different energisers has been tested. In a work carried out by Okongwu in 1989, he assessed the efficacy of some naturally occurring mineral carbonates as energizers in pack carburization, the objective of the research work was to reduce cost and pollution problem associated with the use of chemically pure or commercial carbonates of calcium, sodium, and barium. The researcher observed that reasonable case depths were obtained with the naturally occurring mineral carbonates, when compared with the commercial carbonates. In the work, he concluded that it was possible to substitute the commercial carbonates with the naturally occurring mineral carbonates (Okongwu, 1989). Ihom et al. in 2013 carried out a research on the use of waste egg shells as energizers in the case hardening of mild steel the result was impressive as he observed a case depth of 0.71 mm after pack carburizing for 3 h (Ihom et al., 2013). Aramide et al. in 2010 used bones for the pack carburization of mild steel. The operation was carried out at temperatures of 850, 900, 950°C and soaking time of 15 and 30 min. Despite the short interval of soaking time, he had impressive result with improvement in the case depth and other mechanical properties of the mild steel (Aramide et al., 2010). This can be linked to the fact that bones contain both calcium carbonate and carbonaceous material. A typical bone mineral composition is as presented in Table 1. The composition shown in Table 1 explains why bone alone was used as a carburizing material by Aramide et al. (2010). The organic component serves as the carbonaceous material while the carbonate in the inorganic component serve as energizer. As observed by Okongwu, the use of the naturally occurring carbonates reduces cost of buying commercial chemical carbonates and also pollution problems. Cowbones constitute solid waste problem therefore exploring ways of utilizing them is very crucial and good. The objective of this work is to case harden mild steel using cowbone as energizer. Mild steel finds application in engineering components such as gears, shafts, car bodies, and several other areas and case hardening is normally applied to increase the wear resistance of these components. It gives the component a hard case and a tough core (Ihom et al., 2012). African Journal of Engineering Research Vol. 1(4), pp. 97-101, October 2013 Full Length Research Paper