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

Abstract

The mechanism of graphite formation on gray cast iron metal during carburisation process using organic nanocarbon (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.

Rinser Machine and the Dynamics-based Failure Analysis for Spur Gear Fault Detection: A Forensic Review

“…The combination of silicon present in the melt and slow cooling conditions promotes the formation of graphite rather than iron carbide. This form of cast irons frequently comprises about 2.5 -4 % carbon content, 1 -3 % silicon content and meagre amounts of manganese additives [49]. The matrix of this metal has embedded carbon within it-in the form of flake graphite-in phases of ferrite, pearlite, or various combinations of the two.…”

Cast Iron Cooling Rate Variation Using Cooling Channels: A Numerical Approach

“…Fast cooling results in grain refinement, while slow cooling produces coarse grain. The microstructural features of iron-based materials are refined with higher cooling rates [8] and this has an attendant positive impact on the mechanical properties [9][10][11]. It is, however, important to ensure even cooling as uneven cooling produces low-quality cast.…”

On the analyses of carbon atom diffused into grey cast iron during carburisation process

“…Recent study on the diffusion of palm kernel and eggshell additives to grey cast iron resulted in increase in the hardness of the material 6 . The tribological properties of the treated material via diffusion process was excellent which made it suitable for advanced engineering material 7 , 8 . The principle of Fick’s second law had been limitedly used in evaluating the depth of the mechanical properties that had been diffused into these materials, thus making the analysis or establishing the statistical significance of the diffused carbon atom a major problem 9 – 11 .…”