Journal of Casting & Materials Engineering
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ISSN 2543-9901
Issue Date
2022
Volume
Vol. 6
Number
No. 1
Description
Journal Volume
Journal of Casting & Materials Engineering
Vol. 6 (2022)
Projects
Pages
Articles
The correlation between solidification rates, microstructure integrity and tensile plastic behaviour in 4.2 wt.% silicon strengthened ductile iron
(AGH University of Science and Technology Press, 2022) Angella, Giuliano; Taloni, Marcello; Donnini, Riccardo; Zanardi, Franco
High Silicon Strengthened Ductile Iron (HSiSDI) with 4.2 wt.% of silicon was produced in Y-blocks with different thicknesses to investigate the effects of the solidification rate on microstructure integrity and tensile mechanical properties. With decreasing solidification rates, the graphite degeneracy with the appearance of chunky graphite became more significant at the highest silicon contents, so chemical ordering and graphite degeneracy seemed to be qualitative explanations of tensile property degradation. However, a deeper analysis of the relationship between solidification rate, microstructure and tensile properties was realized through an innovative approach based on the Matrix Assessment Diagram (MAD), where the parameters of Voce equation resulting from best-fitting the experimental tensile flow curves of a significant number of HSiSDI samples, were plotted. For 3.5 wt.% silicon content, the MAD analysis indicated that the microstructure was sound for any solidification rate, while for 4.5 wt.% the microstructure was sound only for the fastest solidification rates. For 4.2 wt.% silicon content the MAD analysis pointed out that the tensile plastic behaviour and the microstructure integrity was in between the 3.5 and 4.5 wt.% silicon contents, representing a composition threshold where the reliable microstructures were only found with the fastest solidification rates, while considerable variability was found for the slowest ones. Support to the MAD analysis results was given from microstructure observations.
An analysis of the features of cast composite materials based on light alloys reinforced by particles
(AGH University of Science and Technology Press, 2022) Dan, Olena Leonìdìvna
Light alloys are widely used in industry and everyday life due to their high physical and mechanical properties, wear and corrosion resistance, as well as low cost. In this regard, the use of light alloys as a basis for composite materials is both justified and expedient. The potential of these materials has not been fully used to this day, despite the growing interest in metal matrix composites and extensive investigations aimed at the development of production technology and the introduction of advanced systems based on light matrices. The article presents a short review of the analysis of the main components of the technology of cast composite materials based on light alloys of aluminum and magnesium reinforced by particles. Particular attention is paid to the choice of the matrix alloy, the type, size and amount of reinforcing particles introduced into it, as well as the thermal-time and kinetic parameters of the process.
Structural and morphological evaluations of natural hydroxyapatite from calcined animal bones for biomedical applications
(AGH University of Science and Technology Press, 2022) Ojo, Olusola Emmanuel; Sekunowo, Olatunde Israel; Gbenebor, Oluwashina Philips; Adeosun, Samson Oluropo; Ilomuanya, Margaret Okonawan
Several biomedical materials have been employed as drug delivery systems, but natural Hydroxyapatite (HAP) has been proven to be exceptionally better than other materials owing to its excellent bioactivity and biocompatibility properties. In this study, natural HAP was obtained from bovine and caprine bones and comparatively analysed for biomedical applications. The bones were hydrothermally treated, calcined in the temperature range of 700-1100°C, held for 2 hours in an electric furnace to remove the organic contents, milled, sifted with 150 μm mesh sieve and then characterized. It was revealed by Energy Dispersive X-Ray Spectroscopy (EDS) that the bovine and caprine bone samples calcined at 1000°C had calcium/phosphorus ratio (Ca/P) of 1.66 closest to the standard of 1.67. The bovine HAP showed the best crystallinity (86.23%) at 1000°C while caprine HAP had its highest (87.25%) at 1100°C. Fourier Transform Infrared Spectroscopy (FTIR) results revealed that the calcination temperature must be greater than 700°C to isolate high quality HAP. The Scanning Electron Microscopy (SEM) showed that the samples calcined at 800°C had the largest average particle size (85.34 μm) while porosity increases with calcination temperature in both samples. The HAP obtained at a calcination temperature of 1000°C proved to have the best quality for biomedical applications.
Strength, water absorption, thermal and antimicrobial properties of a biopolymer composite wound dressing
(AGH University of Science and Technology Press, 2022) Chiosa Odili, Cletus; Sekunowo, Olatunde Israel; Ilomuanya, Margaret Okonawan; Gbenebor, Oluwashina Philips; Adeosun, Samson Oluropo
Conventional wound material allows bacterial invasions, trauma and discomfort associated with the changing of the dressing material, and the accumulation of body fluid for wounds with high exudate. However, there is a shift from conventional wound dressing materials to polymeric nanofibers due to their high surface area to volume ratio, high porosity, good pore size distribution, which allows for cell adhesion and proliferation. There is an urgent need to synthesis a biodegradable composite that is resistant to bacterial infection. In this study, an electrospun polylactide (PLA) composite suitable for wound dressing, with enhanced antimicrobial and mechanical properties, was produced. The neat PLA, PLA/CH (10 wt.%), PLA/CH (5 wt.%), PLA/CHS (10 wt.%), PLA/CHS (5 wt.%), PLA/CH (2.5 wt.%) /CHS (2.5 wt.%) and PLA/CH (5 wt.%)/CHS (5 wt.%), were electrospun using 0.14 g/ml solution. Results show that crystallinity (67.6%) of neat PLA declined by 3.8% on the addition of 2.5 wt.% chitin/chitosan with improved hydrophilicity of the composite. The tensile strength of neat PLA (0.3 MPa) increased (0.6 MPa) with 2.5 wt.% chitin/chitosan addition. The slight increase in the glass transition temperature from 75°C for neat PLA to 78°C of the composite fibre, showed improved ductility. The fibres showed little beads, hence suitable for wound dressing. The electrospun mats have good water absorption capacity and strong resistance against <i>Staphylococcus aureus</i>. Good performance was attained at 5 wt.% of chitin, chitosan and hybrid reinforcements. Therefore, a PLA/chitin/chitosan composite is recommended as a wound dressing material.