RESUMO
The isothermal heat treatment process has been identified as a unique process of fabricating exceptional graphite cast iron due to its remarkable mechanical properties, such as excellent machinability, toughness, and high level of ultimate tensile strength. Austempered ductile iron (ADI), ductile iron (DI), and gray cast iron (GCI), known as spheroidal cast irons, are viable alternative materials compared to traditional steel casting, as well as aluminum casting. The graphite nodules from the microstructures of DI, ADI, and GCI are consistently encompassed by acicular ferrite and carbon-saturated austenite in the matrix, forming a distinctive ausferritic structure. All these materials are extensively used in the fabrication of engine sleeves, engine blocks, valves, gears, and camshafts in the automobile sector. With relative motion and outward loads, these components are regularly exposed to surface contact. In this project, it was observed that austempering temperature and a shorter holding period could also be used to manufacture needle-like ferrite platelets for austempered ductile iron (ADI) and other graphite cast irons. To overcome the brittleness challenges and catastrophic failures encountered by applied loads in present-day applications, it is essential to comprehend the isothermal treatments, morphological behaviors, phase analyses, processing techniques, and mechanical properties needed to properly incorporate these materials into future designs. This review article provides detailed information on the characterization and relevant potential mechanisms of ADI, DI, and GCI.
RESUMO
Recently, the issues of land-based plastics and their associated challenges in the marine world have been widely publicised in the media and scientific literature. Thus far, despite these communications, there have been few reports that have focused on the issues that acute plastic waste generation and its poor management pose to human health and the global environment. Also, articles on ways to mitigate these issues particularly in sub-Saharan Africa have not been documented. Indeed, there is significant scope for improvements in plastic waste management in developing countries, which offer a wide range of economic and environmental benefits. Plastic waste generation in sub-Saharan Africa is dependent on many factors like urbanization, etc. Currently, the population of sub-Saharan Africa is around 1 billion as of the year 2019, the amount of generated waste is 180 million tonnes at the rate of 0.5% per capita per day, the amount that is openly dumped is 70% and the plastic waste generated annually is 17 million tonnes. Therefore, this study aims to provide an overview of the plastic lifecycle and problems associated with plastic waste management in sub-Saharan Africa, including current practices, public participation and opinion, and government regulations. In addition, this highlight aims to outline the impact of plastic waste proliferation on man and the environment; and the economic and environmental benefits of proper plastic waste management. Critical discussion of current processes and the suitability of potential solutions provide the basis for proposition on mitigation measures to avert the negative impact of plastic waste.
