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This study was centered on improving the mechanical properties of AISI 8620 steel using the carburization technique. The failure in service conditions of many steel components such as cams, gears, and shafts necessitated the research as it demands that they possess both high wear-resistant surfaces and tough shock-resistant cores. Standard test samples prepared from the steel material were subjected to a pack carburization process using rice husk and charcoal as carburizers, and the energizer – calcium trioxocarbonate (IV) at temperatures of 800, 850, 900, and 950 °C, and held for 60, 90, and 120 minutes. The samples were quenched in water and tempered at 500°C for 60 minutes. After the pack hardening process, the test samples were subjected to tensile, impact, and hardness tests. From the data obtained, ultimate tensile strength (UTS), Hardness, Young’s Modulus, engineering strain, and impact strength were calculated. The case and core hardness of the carburized samples were noted, and an optical microscope was used to observe the microstructural features of the case-hardened, quenched, and tempered samples. The responses (mechanical properties of steel) were optimized using response surface methodology to obtain the optimum carburizing conditions-temperature and holding time. Results showed that the sample’s microhardness core and microhardness case increased from 253 to 327 HV and from 243 to 339 HV as the holding time increased from 60 to 120 minutes, indicating an appreciable increase in the mechanical property of the samples. The optimum carburizing conditions were at a temperature of 885 °C and a holding time of 120 minutes. Hence, the carburization of AISI 8620 steel using rice husk and charcoal as carburizers improved the steel material’s case, core, and mechanical properties.

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The thermal behavior of a ceiling board produced with breadfruit seed coat as the filler material, and recycled Low Density Polyethylene, as the binder, was investigated. The Breadfruit seed coat was treated with sodium hydroxide and acetic acid, to remove the pigments. The ceiling material was produced with 19.722% filer-binder ratio, and pressed for 10 minutes, at temperature and pressure of 197.31 oC and 9.042 MPa respectively. Lee-Charton’s apparatus was used to determine the thermal conductivity of the produced material, which gave a value of 0.362 Wm− 1K− 1 and the corresponding thermal diffusivity and resistivity of 5.24 x 10− 7 m2/s, and 2.76 Wm− 1K− 1, respectively. Thermo-gravimetric analyzer and Digital Scanning Calorimeter was used to study the thermal behavior the filler material and the produced sample, which showed a good thermal stability. Hence, this research showed that the produced material is suitable for ceiling board application.

Heat production associated with every machining operation has a significant effect on the cutting temperature and drilling time. Such effect is mitigated through the application of cutting fluids that would help to conduct off the generated heat actuated by the frictional contact between the tool and workpiece cutting zone. The effects of the vegetable oils (Gmelina oil, Neem oil and Castor oil) and conventional soluble oil on the cutting temperature and drilling time were studied at various spindle speeds, feed rates and cutting speeds. The vegetable oils were extracted from their various seeds using solvent and pressing method. A minimum quantity lubricating (MQL) system was set-up and was used to control the flow of the cutting fluid to the drilling zone of the tool-workpiece interface. A vertical drilling machine having a 20mm drill bit size was used to drill a through hole of 40mm depth on a mild steel material. During the drilling process, the cutting fluid was applied to the drilling zone using the MQL system and the cutting temperature and drilling time were measured with an infra-red thermometer and a stop watch respectively. The results gotten from the experiment showed that Gmelina oil gave the lowest cutting temperature and drilling time. This was followed by soluble oil, Neem oil and then Castor oil. Under a dry drilling condition, the cutting temperature and drilling time obtained were the highest compared to other cutting fluids applied conditions. Therefore, cutting fluids application reduces the cutting temperature and drilling time and should be employed in industrial operations for the attainment of good machining characteristics.