Investigation of the effects of selected bio-based carburising agents on mechanical and microstructural characteristics of gray cast iron

Enesi Y Salawu; Oluseyi O Ajayi; Anthony O Inegbenebor; Stephen Akinlabi; Esther Akinlabi; A P I Popoola; U O Uyo

doi:10.1016/j.heliyon.2020.e03418

Investigation of the effects of selected bio-based carburising agents on mechanical and microstructural characteristics of gray cast iron

Heliyon. 2020 Feb 22;6(2):e03418. doi: 10.1016/j.heliyon.2020.e03418. eCollection 2020 Feb.

Authors

Enesi Y Salawu¹, Oluseyi O Ajayi^{1

2}, Anthony O Inegbenebor¹, Stephen Akinlabi^{1

3

4}, Esther Akinlabi^{1

3}, A P I Popoola², U O Uyo²

Affiliations

¹ Department of Mechanical Engineering, Covenant University, Ota, Nigeria.
² Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria, South Africa.
³ Department of Mechanical Engineering Science, University of Johannesburg, South Africa.
⁴ Department of Mechanical Engineering, Walter Sisulu University, South Africa.

Abstract

The mechanism of graphite formation on gray cast iron metal during carburisation process using organic nano-carbon (ONC) was investigated at 900 °C for a holding time of three (3) hours. TEM and XRD were employed to characterize the pulverised nano-carbon to determine their phases and bonding potentials. Also, SEM/EDS, XRD and Vickers' hardness tester were employed to determine the microstructure, phase compositions as well as hardness and wear properties of the carburised material. The microstructural result showed that, there was uniform carbon diffusion into the substrate material which led to layers of graphite formation and subsequent surface modifications for each of the selected nano-carbon used. Also, the XRD results revealed variations in the peak patterns for each of the substrate carburised with different organic carbon with substrates showing graphite and iron phases as observed in that carburised in pulverised palm kernel shell having broad peaks at 35.50^o, 44.4^o, 65.12^o and 82.395^o. This is traceable to amorphous properties and crystalline behaviour of the organic carbon. Further to this, the micro-hardness measurement showed that substrate carburised using pulverised palm kernel shell performed better compared to other substrates in other media with a micro hardness value of 355.8 (HV) against as-received which is 116.9 (HV). Thus, this is a novel and possible method of improving the properties of grey cast iron to meet the increasing demand in gear applications.

Keywords: Carburization; Gears; Materials science; Mechanical engineering; Mechanical properties; Organic carbon; Production; Wear.