http://irepo.futminna.edu.ng:8080/jspui/handle/123456789/59 Material and Metallurgical Engineering 2026-05-03T00:24:17Z http://irepo.futminna.edu.ng:8080/jspui/handle/123456789/30680 Title: Carbon nanotube-reinforced polymer nanocomposites for sustainable biomedical applications: A review. Authors: Abubakre, O. K.; Medupin, R. O.; Akintunde, Idris; Jimoh, O. T.; Ukoba, K. O.; Jen, Tien-Chien; Yoro, K. O. Abstract: The search for viable alternatives to conventional materials in biomedical applications is as important as the movement for the adoption of a sustainability approach in the production of polymer nanocomposites for prosthetic purposes. Carbon nanotube (CNT) reinforced polymer nanocomposites have become the center of the present prosthetic industry due to their unparalleled strength-to-weight characteristics. However, the categories of polymers used for this purpose and their long-term impact on the environment have generated controversies among researchers. The adequacy, affordability, and sustainability of materials for the development of prosthetics are some of the common concerns. Consequently, this review addresses concerns about the adherence to SDGs in biomedical manufacturing which focuses on material selection considering environmental impacts. In addition, contributions from previous research were reviewed based on the remarkable increase in the number of publications on CNT-reinforced polymer nanocomposites over the last 10 years. Various findings by researchers in the field who used natural rubber and other polymers as host matrices were analyzed from the perspective of sustainability. While considerable progress has been made in the use of other polymers in the biomedical field, only a few publications have targeted natural rubber. This review provides insights into opportunities for sustainable production and consumption of devices with biodegradable CNT/natural rubber nanocomposites. 2023-06-01T00:00:00Z http://irepo.futminna.edu.ng:8080/jspui/handle/123456789/30679 Title: Selection of a suitable wear-resistant metal matrix composite for remanufacturing continuous miner cutter (CMC) sleeves via a two-step laser-based technique Authors: Lindsay, Emmanuel; Akintunde, Idris; Olakanmi, Eyitayo; Prasad, R.S.V; Botes, A; Pityana, S.L; Skhosane, Samuel Abstract: The premature failure of continuous miner cutter (CMC) sleeves in underground coal mining necessitates remanufacturing to enable a closed-loop system and enhanced sustainable mining operations. However, a techno-economic analysis conducted revealed that exclusively using laser cladding (LC) to remanufacture failed sleeves is not economically viable. Thus, this research aims to explore a two-step laser-based remanufacturing technique that incorporates gas metal arc welding (GMAW) and LC, as well as identify suitable wear-resistant metal matrix composites (MMCs) for restoring damaged sleeves. Consequently, an LC process was used to deposit three MMC materials onto optimised GMAW overlays. A comparative analysis of the manufactured MMC coatings revealed that WC/TiC/AISI4340 coating exhibited a well-consolidated, crack- and pore-free microstructure and a superior microhardness of 931 HV0.5 compared to WC- and TiC-reinforced composites, which had average hardness values of 670 HV0.5 and 744 HV0.5, respectively. Additionally, the WC/TiC/AISI4340 coating demonstrated an excellent low wear rate (0.0007 g/s) comparable to TiC-reinforced coating, and a propensity to extend the sleeve’s lifespan by a factor of four. These enhancements are attributed to the formation of an umbrella-like network of TiC, predominantly distributed in the coating top region and solid solution strengthening [(Ti, W)C] caused by the partial dissolution of WC/TiC carbides and their precipitation into the eutectic carbide network within the interdendritic grain regions. Hence, combining GMAW and LC processes with WC/TiC/AISI4340 presents a promising remanufacturing strategy for restoring mining equipment, offering improved performance, longer lifespan, and economically viable and sustainable mining operations. 2025-09-01T00:00:00Z http://irepo.futminna.edu.ng:8080/jspui/handle/123456789/30678 Title: Formulation of hybrid-carbide reinforced AISI-4340 wear-resistant composite coatings for remanufacturing of conical picks used in coal mining by laser cladding Authors: Akintunde, Idris; Lindsay, Emmanuel; Olakanmi, Eyitayo; Prasad, R.S.V; Botes, A; Pityana, S.L; Skhosane, Samuel; Motimedi, T. Abstract: The presence of quartz (1100-HV0.05) hardness in coal seams results in premature failure of conical picks in the continuous miner (CM) cutter during underground coal mining. This requires that picks are remanufactured with materials that have improved wear resistance, which can withstand quartz. Processability of two laser-cladded hybrid-carbide (WC-SiC and TiC-SiC) reinforced AISI-4340 composite coatings was studied to identify an appropriate material for remanufacturing worn picks with particular attention paid to their microstructural evolution, performance, and costs. WC-SiC reinforced composites were characterised with defective fusion, cracks, and serrations within the clad microstructure, while the morphologies of TiC-SiC reinforced coatings revealed minimal porosity and cracks without serrations. Furthermore, the microhardness of TiC-SiC coatings is between 1102 and 2753 HV0.5, compared to WC-SiC coatings with a microhardness range between 1066 and 1365 HV0.5. Higher microhardness values of TiC-SiC coatings are attributed to the larger TiC particles retained, compared with the minimal quantity of WC retained particles that settled at the bottom of the coatings. In addition, TiC-SiC coatings have improved wear resistance with a volume loss of 33 mm3 as compared to 71 mm3 for WC-SiC coatings. Comparative analysis of the performance and cost indices of hybrid composites with those of TiC-AISI 4340 and WC-AISI 4340 composites suggests that the hybrid TiC-SiC reinforced AISI-4340 composite performs best at a lower cost. Hybrid TiC-SiC reinforced AISI-4340 composite is hereby recommended as a cheaper remanufacturing material for restoring damaged CM’s picks to as new in performance or reinforcing newly purchased picks to prolong their service life during coal mining. 2026-01-26T00:00:00Z http://irepo.futminna.edu.ng:8080/jspui/handle/123456789/30677 Title: Optimised consolidation and characterisation of TiC-SiC reinforced AISI-4340 composite coatings for conical picks remanufacture Authors: Akintunde, Idris; Lindsay, Emmanuel; Olakanmi, Eyitayo; Prasad, R.S.V; Botes, A.; Pityana, S.L; Skhosane, S; Motimedi, T Abstract: TiC-SiC-reinforced AISI-4340 composite clads have been identified as a suitable material to remanufacture worn conical picks. However, the inherent defects in the clad produced, the industrial requirement to improve clad microhardness, and abrasive wear resistance necessitate the need for optimising laser processing and material parameters. Therefore, this research is conducted to investigate the effects of the powder feed rate, the scanning speed, the angle of inclination of the nozzle, and the yttria addition on the quality characteristics of the coating. The results show that as the feed rate increases from 6 to 8 g/min, the clad height increases, and the width decreases due to the reduced spreadability of the viscous melt pool. Clad height and width decrease as scanning speed increases from 0.4 to 0.5 m/min, attributed to reduced laser energy-powder interaction (LEPI) time. Furthermore, as the nozzle is inclined 2° and 4° away from the vertical, this results in an increased width and a reduced height due to the reduction of the beam deflection (increasing heat input) and loss of powder particles before reaching the focal point. Thus, the carbide melts (carbide dissolution) and reduces the reinforcing effect, leading to a decrease in wear resistance. Moreover, the addition of yttria lowers the dissolution temperature of the carbides, with a consequent increase in width and a lesser height of the clad. The geometric analysis of optimised clad established coatings with 2.3 mm height, minimal weld penetration (0.4 mm), and small HAZ of less than 1.4 mm produced. Furthermore, the microstructure revealed a homogenous dispersion of retained TiC particles in the morphology of the lath martensite, with minimal (2.6%) porosity. Additionally, the coating has the highest amount of TiC particles retained in the AISI-4340 matrix with an average microhardness of 1743 HV0.5 and 26.24 mm3 volume of material loss. The use of optimised clads for remanufacturing worn CM picks to be as new will adequately withstand the hardness of engrained quartz (1100-HV0.05) in the coal seam during underground cutting of the coal mass, thus mitigating the premature failure of the picks. 2025-07-29T00:00:00Z