The increasing need for materials with light weight, high resistance to corrosion and wear, toughness and strength, machinability, high thermal capacity etc. for various applications is unending. This demand has continued to stretch the exploitation and manipulation of various functionally graded materials (FGMs) and their production methods. This study explores one of the FGM production processes called the centrifugal casting technique (CCT). The centrifugal casting process has several potential advantages over traditional casting methods. This study provides information regarding the basic functionally graded production methods and their applications and also discusses categories of CCT, evolution and process parameters.

This study focuses on primary impurities, called intermetallics, in the microstructure of Al-SiX alloys, their formation, effects and treatments to eliminate or ameliorate their deleterious effects. Intermetallic compounds are usually formed when alloying elements, such as Fe, Cu, Mn, Mg and Sr. are added to Al-Si based alloys. These elements are depicted by X in the alloys formation expression. The chapter noted that the most common intermetallics are iron (Fe) based, and several of these Fe-phases, including the most harmful Fe-phase, β-Al 5 SiFe, are listed and discussed. Fe-phase intermetallics are deleterious to the mechanical properties of Al-alloys; however, addition of <0.7% Fe helps prevent soldering in die casting mould. The effects of Fe-phase and other intermetallics formed by Cu, Mg and Mn were examined. Further, some techniques of eliminating or mitigating the negative influences of intermetallics were discussed.

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This chapter discusses the concepts, casting techniques and applications of functionally graded materials metal matrix composites (FGMMCs). Considerations were given to bulk functionally graded aluminium matrix composites (FGAACs) production processes. Liquid-metal forging processes of FGAACs fabrication, such as infiltration process, squeeze casting, friction casting or compocasting, stir, and centrifugal casting were discussed. The chapter provides basic concepts of the processes and overview of their processing parameters, such as mould rotational speed; reinforcement particles size and volume; degassing method; melting and pouring temperatures; pressure; and stirrer. The study notes that functionally graded materials (FGMs) are commonly used in automotive, aircraft, aviation, chemical, medical, engineering, renewable energy, nuclear energy, and optics electronics industries.

This paper discusses the main Functionally Graded Materials (FGMs) and their bulk fabrication techniques, their development, principles and applications. The fabrication processes considered include powder metallurgy (PM), sintering, squeeze casting, infiltration process, compocasting, centrifugal casting, stir casting, material prototyping. The paper provides an overview of the FGM processing parameters including reinforcement particles size and volume %, temperature, pressure (for PM), and stirrer and mould rotational speeds (for stir and centrifugal casting processes respectively). The paper notes that the FGMs are widely used in the following sectors: automotive, medical, aerospace, aviation, nuclear energy, renewable energy, chemical, engineering, optics electronics etc.

Flowing water has hydraulic energy that can be transformed into electrical energy, sub-Saharan Africa has an abundance of hydro resources that are untapped. In this study, various barriers limiting the use of small hydropower to tap the abundant hydro potentials for power generation are discussed. These barriers include insufficient fund; lack of adequate manufacturing infrastructure; lack of adequate power generation and distribution policies; inaccurate hydrological data; insufficient human and power infrastructure capacities; and inadequate domestic and regional participation in design and manufacture of small hydropower component devices and systems. This study sees hydro as a cleaner energy source and small hydropower as the best power system for rural and remote areas and for stand-alone electrification. For power sustainability in the region, public–private partnership, domestication of small hydropower technologies and less reliance on foreign technologies and international support are key factors.

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