Advances in Science and Technology Vol. 116

Abstract: The use of aluminium as material of choice in the manufacture of window and door openings in Mauritius has escalated significantly in recent years. This has given rise to a considerable number of small-and medium-sized companies operating in the aluminium fabrication sector. The main aim of this study was to identify and investigate the common problems reported with aluminium openings and to assess the structural resistance, water-tightness and safety of the openings. A survey was carried out among local aluminium importers and fabrication companies to gather information about the different profiles and grades of aluminium commonly used for exterior window and door applications in the residential sector. A questionnaire was designed and circulated to clients of aluminium fenestration products. This helped to identify the most common problems encountered with aluminium openings. Site visits were also conducted which enabled the investigation of some common problems identified such as water ingress and rigidity of moving parts. The structural loading of openings was assessed using finite element analysis using SolidWorks. Models of openings of different sizes and corresponding to typical opening designs used locally were created and a uniform pressure was applied on the frames. This uniform pressure was derived from a wind speed of 280 km/h – the maximum wind speed used for design calculations for buildings in Mauritius. The resulting deflections were analysed and compared to the maximum permissible deflections – which were calculated using the guidelines of North American Fenestration Standard (NAFS-11). Results showed that the maximum deflections for frames sizes exceeding a span of 1.5 m, exceeded the maximum allowable values, and necessitated the use of more rigid profiles. Deflections observed in the triple frame design were also higher than those in the double frame. These observations point out to the need of selecting the right profiles for different sized applications to ensure that openings do not incur significant deflections when subjected to wind loads, which would be encountered during severe cyclonic conditions in the island.

Abstract: The increase in the production and utilization of plastics has created a never-ending problem of plastic waste. Developing countries face challenges with plastic waste disposal that in due process negatively impacts the environmental ecosystem. That notwithstanding, it suffices to mention that most developing countries have poor road networks that pose a burden towards smooth economic and social development. The problem is further exacerbated by the limited availability of bitumen which is usually imported but also has environmental concerns. It is against this background that we proposed alternative binders from plastic waste which can help developing countries to manage plastic waste as well as build road networks, thereby leading to sustainable development. We explored the 80/100 penetration grade bitumen modification (Penetration grade 85 and Softening temperature 46°C) using polyethylene terephthalate (PET) waste (2 – 12%) and lignin (0.2%) as a crosslinking agent by weight for every PET waste – Bitumen sample. The research showed that Plastic waste and lignin improved the performance of bitumen. The modified bitumen with 10% waste PET and 0.2% lignin enhanced the softening point and penetration points to 55°C and 46, respectively; hence the incorporation of PET and lignin provided better properties compared to the neat bitumen.

Abstract: The utilization of vegetable oil in producing bio-based polyol, as an alternative replacement to petroleum-based polyol in making polyurethane (PU) foam has gained a lot of interest due to its finite supply and low production cost. In this study, bio-based polyol using coconut oil as raw material produced PU foam as thermal insulation material. The vegetable oil-based polyol was prepared using a two-step method, while PU foams were prepared by the free-rise method. In order to enhance the thermal properties of the produce PU foams, phase change material (PCM) was added to the PU foam formulation. FTIR spectra result showed peaks at 2920 cm^-1 and 2850^-1, which signifies the CH2 asymmetric stretching, indicating that n-octadecane was successfully incorporated into PU foams. Moreover, heat flow meter (HFM) and thermo-gravimetric analysis (TGA) show PU foam with 1% n-octadecane shows better thermal properties than other produced PU foams. Furthermore, the universal testing machine (UTM) result shows an enhancement in the mechanical properties of the produced PU foam. These results demonstrate that the addition of n-octadecane to the PU foam formulation improved the mechanical properties of PU foams while enhancing their thermal properties.

Abstract: Basic oxygen furnace slag (BOF slag) contains high amount of useful oxides such as CaO, MgO, SiO₂, etc., therefore, a solution of the slag recycling would be used as a flux in pelletizing process. To understand role of slag in the pellet, this research examines the mechanical, chemical and microstructure properties of the pellets containing various amount of the slag. In the experimental process, the green pellets were made from a mixture of bentonite, iron ore and the slag. The green pellets were sintered in the resistance heating furnace maintaining temperature at 1200 °C for 120 minutes. Then the fired pellet was tested strength and observed microstructure with variation of the slag amount in the pellets. The result shown that cold compression strength of the pellets containing from 1.06 to 18.45 mass% slag was higher values than 200 kg/p, hence, the pellet was able to charge the pellets into the blast furnace. The highest strength was 342 kg/p with 5.08 mass% slag in the pellet. Besides, optical observed microstructure of the pellet indicated the phases of magnetite, hematite and silicate. In addition, the obtained results shown that there was a deterioration of porosity with increasing the slag amount. Accordingly, the porosity got a slight decrease when the slag amount increased from 1.06 to 5.08 mass% in the pellet. Once the amount of the slag was higher than 5.08 mass%, the porosity significantly reduced with increasing the slag amount; the porosity decreased from 23 to 12 %.

Abstract: High amount of basic oxygen furnace (BOF) slag in steelmaking process is a big challenge, therefore, recycling of the slag have been extensively concerned by not only steelmakers but also researchers. One of the promising methods is to use the slag as a flux in the pretreatment process because the basicity of slag is high and it contains high amount of MgO and CaO. This study examines recycling ability of the BOF slag as a part of the flux adding to the pretreatment process. In the experiment procedure, the flux was combination of the slag (59 mass%), CaO (32 mass%) and SiO₂ (9 mass%). The flux and the iron sample were put into the crucible, and then set up in the resistance furnace. The experiments were carried out at different temperatures of 1450, 1500 and 1550 °C with holding time of 15 minutes. The results shown that the S content in the iron significantly decreased in all cases of temperatures. S content in the iron in the pretreatment process reduced from the initial value to 0.007 mass% at the temperature of 1450 °C. However, at temperature of 1550 °C, the S content in the iron was 0.012 mass%. Besides, Si content in the iron reduced with increasing temperature; Si content in the iron significantly decreased from initial value of 2.67 mass% to 0.05 and 0.06 mass% once the temperatures were 1500 and 1550 °C, respectively. Additionally, it was indicated that Fe content in the slag after reaction dropped from the initial value of 6.20 mass% to 0.62 mass% at the temperature of 1550 °C.

Abstract: In the current advancing world, operability and ease in processability of a material define its selection criteria for the intended applications. Hence, the industrial applications requiring high temperature sustenance, strength and corrosion resistance desperately demand the materials which employ simple processing in an economical way. Contemplating last few decades, it has been discovered that industries like petrochemical, power generation, nuclear energy, etc. greatly relied on nickel-based alloys till Fe-Ni-Cr based alloys were not introduced. The usable components are obtained either in cast or wrought form as per requirements. Fully killed alloy, developed under controlled conditions with some precautions during the casting process can lead to sound casting. The current study adopts a novel preliminary approach to control the quality of cast UNS N08120 material and minimize the possibility of defect generation. The possible reasons behind cast defects and how they transform into intrinsic defects have also been discussed. Calcium-based fluxes are introduced to molten metal as a degassing agent for the elimination of lighter impurities and entrapped gases. By the addition of quicklime (CaO) as a flux material during the sand casting process, an attempt has been made to reduce the presence of gases and impurities by more than 80%.

Abstract: In laser cladding process, generation of high temperature gradients significantly impacts the output coating parameters such as mechanical and microstructural properties. Buffer layer addition between hard alloys cladding shows reduction in crack formation and also dilution rates. The present study is on Insitu temperature monitoring in laser cladding of Stellite 6 alloy with addition of buffer layer, which were compared with direct deposition of Stellite 6. The results show about 17 - 20 % low substrate temperatures with a buffer layer, indicates more uniform cooling of the hard coatings than direct cladding. The increase in laser power measures 35 - 40 % higher temperatures in both the cases due to large heat addition at the clad region. The study provides an insight into the substrate temperature evolution in cladding with and without a buffer layer.

Abstract: A digital twin is among the fast-growing technologies capable of increasing the dynamic development of manufacturing industry in terms of digital transformation in the context of Industry 4.0. The development of digital twin technologies for carbon fiber composites (CFC) recycling is a novel direction that significantly improves the recycling process efficiency. Among various benefits, it provides high-quality process monitoring and automated control. However, digital twins development of CFC recycling face challenges that need to be identified. This study aimed to investigate the challenges of implementing digital twin in the carbon fiber composites recycling process. Three main challenges were identified by adopting the narrative literature review approach. Understanding these challenges contributes to the digitalization of the industry and provides recommendations for further investigation of this area of research. It should be noted that optimization and validation of technical aspects will allow the creation of a solid process data management system and control crucial process variables.

Abstract: At the time of unprecedented development of digital technologies, business owners across various industries need to stay up-to-date in terms of using cutting-edge technologies such as Industry 4.0 to ensure competitive performance. There are still many areas where their positive implications of digital technologies have not been applied. For example, the end-of-life (EoL) waste from the automotive, aerospace, and wind energy industries is still accumulating in landfills. At present, an increasing number of vehicles, airplanes, and wind turbine blades are made of Carbon Fiber Reinforced Polymer Composites (CFRPs) leading to an urgent demand for implementing sustainable waste disposal strategies. Thus, recycling CFRPs is a key research area that provides a potential for improvement, particularly, in terms of digitalization. This study addresses the issues prevalent in this sphere and proposes Industry 4.0 related technologies to be integrated into the CFRP recycling supply chain stages, including waste collection, dismantling, transportation, recycling, and re-manufacturing. For this purpose, key technologies were selected from the literature review, smart recycling trends were defined and relevant analysis was carried out to map technologies onto the CFRP recycling supply chain.