Influence of SiC nanoparticle contents on microstructural evolution and mechanical behavior of AZ91D magnesium matrix composites synthesised through a combination of a master pellet feeding technique and stir casting assisted by ultrasonic vibration

In this current study, an integrated approach involving a master pellet feeding technique and stir casting assisted by ultrasonic treatment processing was employed to fabricate AZ91D magnesium matrix nanocomposites reinforced with various concentrations of SiC nanoparticles (1.0, 1.5, and 2.0 wt%). The influence of the nanoparticle feeding method and the weight fraction of reinforcement on the microstructure and mechanical properties of AZ91D/SiC composites was thoroughly examined. The microstructural analysis revealed that the implementation of a master pellet feeding approach resulted in a relatively uniform dispersion of SiC nanoparticles within the primary α–Mg phase, whereas the original nanoparticle feeding method led to noticeable particle agglomeration in the microstructure. Additionally, with an increasing weight fraction of SiC nanoparticles, the primary α-Mg grain became finer and the β-Mg17Al12 intermetallic phase turned smaller. The hardness and tensile properties of AZ91D/SiC composites were significantly enhanced with increasing SiC contents. The addition of 2.0 wt% SiC reinforcements to the AZ91D magnesium alloy resulted in a maximal hardness increase of 41 %. Nevertheless, the ultimate tensile strength (UTS) and elongation (%EL) decreased when the SiC content exceeded 2.0 wt% due to the presence of increased porosity content and particle clusters in the microstructure. Notably, the AZ91D/1.5 wt% SiC composite exhibited promising tensile properties, with yield strength (YS), ultimate tensile strength (UTS), and elongation (%EL) values of 151 MPa, 192 MPa, and 4.54 %, respectively

Corrosion fatigue of phosphor bronze reinforcing tapes on underground power transmission cables - Failure analysis

This paper is an investigation on the failure mechanism involved in underground power transmission cables with their life limited by corrosion of phosphor bronze reinforcing tapes. In the present work, a detailed analysis of failed bronze tapes in an ammonium free environment has been undertaken and corrosion fatigue failure mechanism has been identified. A detailed examination of the tape samples is carried out using 2D and 3D optical microscopy and SEM. It follows a mechanical approach that confirms corrosion fatigue as the failure mechanism. SEM images reveal that the pits present on the surface could be the starting point for the crack that eventually leads to failure. Stress calculation shows that the tape could fail only if corrosion pits are present on the tape surface. Presence of corrosion pits, multi cracks and striations on the fractured surface demonstrates corrosion fatigue cracking as the failure mechanism across the tape samples

Research into sustainable surface finishing at the University of Leicester

Sustainability is at the forefront of all research carried out at University of Leicester. There are three main groups contributing to the surface finishing effort: the Centre for Sustainable Materials Processing, the Mechanics of Materials research group and Space Park Leicester; however many collaborations occur across the institution and with industrial partners, including the Materials Innovation Centre with TWI Ltd. The ongoing projects vary across a range of themes, from forensic science to batteries and energy storage. This work aims to give a brief overview of the research groups, centres and institutes, and highlights some relevant projects that fall within the scope of Transactions of the IMF.</p

Impedance spectroscopy characterization of neutron irradiated thermoelectric modules for space nuclear power

The European Space Agency is currently supporting the research and development of advanced radioisotope power systems utilising thermoelectric modules. The performance of thermoelectric modules following exposure to neutron radiation is of significant interest due to the likely application of radioisotope thermoelectric generators in deep space exploration or planetary landers requiring prolonged periods of operation. This study utilises impedance spectroscopy to characterise the effects of neutron irradiation on the performance of complete thermoelectric modules, as opposed to standalone material. For a 50 We americium-241 radioisotope thermoelectric generator design, it is estimated that the TE modules could be exposed to a total integrated flux of approximately 5 × 1013 neutrons cm-2 (>1 MeV). In this study, an equivalent neutron dose was simulated experimentally via an acute 2-hour exposure in a research pool reactor. Bi2Te3-based thermoelectric modules with different leg aspect ratios and microstructures were investigated. Gamma-ray spectroscopy was initially used to identify activated radionuclides and hence quantify irradiation induced transmutation doping. To evaluate the thermoelectric properties pre- and post-irradiation, impedance spectroscopy characterization was employed. Isochronal thermal annealing of defects imparted by the irradiation process, revealed that polycrystalline based modules required significantly higher temperature than those with a monolithic microstructure. Whilst this may indicate a greater susceptibility to neutron irradiation, all tested modules demonstrated sufficient radiation hardness for use within an americium-241 radioisotope thermoelectric generator. Furthermore, the work reported demonstrates that impedance spectroscopy is a highly capably diagnostic tool for characterising the in-service degradation of complete thermoelectric devices

Schools’ air quality monitoring for health and education: methods and protocols of the SAMHE initiative and project

Background: Children spend significant amounts of time at school, making the school environment a potentially important contributor to air quality exposure.  Aim: The SAMHE initiative has a dual aim: 1) to develop and test a bespoke citizen science framework for collecting environment and indoor air quality data in classrooms, alongside contextual data capable of enriching analysis, at an unprecedented scale; and, 2) to simultaneously use these methods to raise awareness among communities regarding their exposure to air pollution in the school environment.  Methodology: To achieve this dual aim, the SAMHE project was initiated to deploy more than 2 000 low-cost indoor air quality monitors in school classrooms. A Web App has been co-designed with schools to support collecting a large comprehensive dataset (including school buildings characteristics, operation, and behavioural patterns) and to enable students and teachers to interact with the data gathered in their school. Results and outlook: We present the design of the interface and visuals that have been co-designed with 20+ schools and tested with 120+ schools. Within one week of the SAMHE launch week, 537 schools had registered to join the project, and at the time of writing (just seven weeks later) this number had grown to around 800 schools. This highlights the potential for this novel initiative to provide a step-change in the way that indoor air quality datasets are gathered at a national and, potentially, international level while simultaneously enabling schools to better manage their indoor environment and empowering students and teachers to reduce their environmental health risks.</p