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Item Influence of sintering temperature on the microstructure, mechanical and tribological properties of ZrO2 reinforced spark plasma sintered Nie-Cr.(KeAi Communications Co. Ltd, 2022-02-01) Oketola, Adeola; Jamiru, Tamba; Adegbola, Adesola Taoreed; Ogunbiyi, Olugbenga; Sadiku, Rotimi; Salifu, SmithThe microstructure, mechanical and tribological properties of NieCreZrO2 composites, manufactured by using the spark plasma sintering technique with different sintering temperatures, were investigated. The individual powder was measured and mixed thoroughly in a tubular mixer for 8 h before being transferred to the sintering machine. The sintering temperatures of 800, 900, 950 and 1000 C with a pressure of 50 MPa, a holding time of 5 min and heating rate of 100 C/min were used as the process parameters in order to develop four compositional composite systems, used in this investigation. Wear tests were, performed on the sintered composites at 10 N, 15 N and 20 N loads. The microstructural analyses of the sintered sample revealed the associated compositional homogeneities, formation of phases and pores. The results showed that the sintering temperature influenced the mechanical and tribological properties of the sintered composites, such that the increasing sintering temperature led to an increase in the relative density. The microhardness and wear resistance increased with the increasing sintering temperature, which showed that the composites developed, possessed improved properties by using high sintering temperature. Thus, the sample sintered at 1000 C maintained the least wear rate and consequently, the best hardness property.Item Effects of sintering temperature on the microstructure, mechanical, tribological and thermophysical properties of GNPs/IN738 composite.(Elsevier B.V., 2023-02-26) Ogunbiyi, Olugbenga; Jamiru, Tamba; Sadiku, Rotimi; Salifu, Smith; Maepa, CharityWhile IN738 Ni-based superalloy is a high strength alloy, it is feasible to improve its properties at the bulk level by reinforcing with graphene nanoplatelets (GNPs), taking advantage of the superior mechanical, tribological and thermal properties using the spark plasma sintering technique. In the present study, the influence of spark plasma sintering temperature range between 900 and 1100 C on the microstructure, mechanical, tribological and thermophysical properties of GNPs/IN738 composite is assessed. The dispersion of GNPs reinforcement and alloying metals to form composite powder is conducted using a turbular mixer and low-frequency planetary ball milling, followed by spark plasma sintering. The relative density of the sintered samples assessed following Archimedes' method indicates increasing densification with the increasing sintering temperature from 94.7% (900 C) to 98.5% (1100 CÞ. The microstructure assessed via SEM, XRD and Raman spectroscopy indicates the formation of precipitate gamma, intermetallic gamma prime, solid solution and GNPs strengthening phases. Thus, the mechanical (micro/nano hardness and Young's modulus), tribological (wear rate and coefficient of friction), and thermophysical (thermal diffusivity, thermal conductivity, and specific heat capacity) properties increased with the increasing sintering temperature. The microhardness increased from 354HV (900 C) to 469HV (1100 C), Nano hardness from 8 GPa (900 C) to 17 GPa (900 C), and Young's modulus from 190 GPa (900 C) to 291 GPa (1100 C). The wear rate reduced with an increase in sintering temperature for the three loads of 5, 10 and 20N. The thermophysical properties assessed from 25 to 600 C show the formation of few inflection points as the temperature increases, which is attributed to the dissolution and rearrangement of precipitate gamma prime and Cr in solid solution phases. Similarly, the small increment in the thermal diffusivity is equally associated with the smoother phonon transition at the GNPs/ matrix interface.Item Influence of sintering temperature on the microstructure, mechanical and tribological properties of ZrO2 reinforced spark plasma sintered Nie-Cr.(KeAi Communications Co. Ltd, 2022-02-21) Oketola, Adeola; Jamiru, Tamba; Yusuff, Adedayo A.; Jimoh, A.A.; Sadiku, Rotimi; Salifu, SmithThe microstructure, mechanical and tribological properties of NieCreZrO2 composites, manufactured by using the spark plasma sintering technique with different sintering temperatures, were investigated. The individual powder was measured and mixed thoroughly in a tubular mixer for 8 h before being transferred to the sintering machine. The sintering temperatures of 800, 900, 950 and 1000 C with a pressure of 50 MPa, a holding time of 5 min and heating rate of 100 C/min were used as the process parameters in order to develop four compositional composite systems, used in this investigation. Wear tests were, performed on the sintered composites at 10 N, 15 N and 20 N loads. The microstructural analyses of the sintered sample revealed the associated compositional homogeneities, formation of phases and pores. The results showed that the sintering temperature influenced the mechanical and tribological properties of the sintered composites, such that the increasing sintering temperature led to an increase in the relative density. The microhardness and wear resistance increased with the increasing sintering temperature, which showed that the composites developed, possessed improved properties by using high sintering temperature. Thus, the sample sintered at 1000 C maintained the least wear rate and consequently, the best hardness property.Item Editorial: Recent development in energy conversion systems.(Frontiers Media, 2024-03-08) Oyedepo, Sunday O.; Abam, Fidelis I.; Ajayi, Oluseyi O.; Samuel, Olusegun D.; Borca-Tasciuc, Diana-Andra; Popoola, Abimbola P. I.In this industrial and technological age, energy plays a principal role in sustainable development. This is connected to issues regarding availability, production processes, utilization, and environmental impact. Due to the increased rate of population growth, the energy demand in the entire world is getting to the level that it may not be sustained in the nearest future if drastic action is not taken to address the situation, especially from research and development perspectives. "None of the millennium development goals (MDGs) can be completed without considerable improvements in the quality and quantity of energy services in developing countries," according to the United Nations Development Programme (UNDP). Based on this fact, UNDP is making efforts, especially in developing countries to ensure that people have access to sustainable sources of clean, reliable, and affordable energy since every aspect of human development is highly impacted by this vital resource. Currently, the available energy conversion systems have limited efficiencies, high operating costs, and environmental effects. Sustainable energy systems are expected to minimize the impact on the environment during their design and operation, to provide economically affordable energy to maximize their benefits to a large population and help mitigate emissions to the environment. This Research Topic welcomes high-quality submissions (original research or review articles) that address issues related to the design, analysis, and improvement of the various energy conversion systems. The aim of this Research Topic is to cover innovative development, and recent and novel research trends focused on the improvement of the operational performance (technical, economic, and environmental) of energy conversion systems (gas/steam power plants; wind turbines; solar thermal system; biomass energy systems, etc.). In addition to original articles, high-quality review papers will be considered for possible publication. Areas to be covered in this Research Topic may include, but are not limited to: • Thermal energy systems: performance and optimization; • Thermionic energy conversion systems; • Assessment and optimization of renewable energy systems – solar thermal, hydro-power system, wind turbine, OTEC, biomass energy system; • Multi-generation energy systems; • Thermo-electric energy conversion systems.Item Influence of tib2 incorporation on microstructural evolution in laser-clad fecrv15 + tib2 deposits(Springer, 2024-05-02) Aramide, B.P.; Jamiru, Tamba; Adegbola, T.A.; Popoola, A.P.I.; Sadiku, Emmanuel RotimiVanadium carbide (VC)-reinforced Fe-based hard facings are pivotal in enhancing the wear resistance of tools prone to mechanical damage. This study investigates the impact of titanium diboride (TiB2) addition (at varying laser power and powder federate) on the microstructure, hardness, wear resistance, and corrosion resistance of high-carbon ferrochrome FeCrV15 clad coatings for agricultural and mining applications. Laser cladding techniques were employed to deposit coatings on steel substrates, and the samples were subjected to comprehensive material characterization, including microhardness testing, wear studies, and electrochemical polarization. Results reveal that TiB2 addition led to visible reactions during deposition, resulting in decreased hardness compared to pure FeCrV15 coatings. Moreover, TiB2 incorporation adversely affected the anticorrosion properties of the coatings, although FeCrV15 coatings exhibited superior corrosion resistance compared to FeCrV15 + TiB2 coatings. Tribological evaluations showed that all coatings exhibited better anti-wear capabilities compared to the steel substrate, with varying degrees of improvement influenced by TiB2 concentration and laser beam power. Overall, FeCrV15 deposits demonstrated superior anti-wear and anticorrosion properties compared to FeCrV15 + TiB2 coatings and attributed to increased convergence of carbide particles and higher grain-boundary density. This research contributes to understanding the intricate interplay between carbide reinforcement and matrix structure in Fe-based hard facings, providing insights for optimizing coating performance in demanding industrial applications.Item Mechanical, wear and corrosion behaviours of laser additive manufactured iron-based heterogeneous composite coatings for tillage tools.(Elsevier B.V., 2024-03-19) Aramide, Basiru Philip; Jamiru, Tamba; Adegbola, T.A.; Popoola, Abimbola Patricia Idowu; Pityana, S.L.Steel is commonly used in engineering components, and it has a high tendency to wear and corrosion attacks when exposed to unfavourable working conditions. The use of chromium-vanadium-iron-rich carbide reinforced iron-based hard facings has become more important in improving the corrosion and wear resistance of such steel subjected to abrasive and impact conditions. In this study, the chromium-vanadium-iron carbide reinforced coatings were developed using in-situ by depositing FeCrV15+Cr powder through laser cladding on carbon steel. The influence of the reinforcement on the microstructure of the coating in relation to its laser processing condition and extra chromium addition was investigated. Furthermore, the effect of the coating’s reinforcement on the hardness, microstructures, anti-corrosion, and anti-wear properties of the carbon steel used in tillage and mining operations was investigated. The result is a defect free deposits with a solid metallurgical attachment to the substrate and improved microhardness. FeCrV15 deposits had a wear-resistant (with a wear rate of 2.42 × 10 6 mm3/N/m) and anti-corrosion capability (with a corrosion rate of 0.001869 mm/yr) that were several folds higher than the steel substrate (with wear rate of 1.72 × 10 3 mm3/N/m and corrosion rate of 0.1168 mm/yr). The general grain refinement of the FeCrV15 deposits was richly enhanced in the iron base matrix. This resulted in outstanding wear and corrosion resistance attributed to the better production of VC–Cr3C2–Cr7C3 particles and better grain refinement of the microstructural formation.