Solid State Phenomena Vol. 318

Abstract: This paper presents a study of three types of Triples steel, where containing 16 to 28 wt.% manganese, 0.8 to 0.89 wt.% Carbon, 9.9 to 11.21 wt.% Aluminum, and with different Nickel content. We investigated the aging effect on properties of Triplex steel by using an optical microscope, scanning electron microscope (SEM) and X-ray diffraction (XRD). The used temperature in the ageing process is 550°C and we take three different times in that process (1min, 1hr, and 5hrs). The microstructure shows one austenite phase of an as-rolled sample without Ni and shows two austenite phases of an as-rolled sample with Ni content. The k-carbide, intermetallic phase (Ni3Al) and annealing twins formation will appear after adding Ni element. Furthermore, those phases will be increased with aging time. X-ray diffraction shows a competitive formation between the k-carbides and intermetallic phase formation during the aging time. It's confirmed that K-carbides will be formed first after that intermetallic phase, where k-carbides were formed at low temperature. Finally, we can conclude from these results that adding Ni in Triplex steel improves the ductility with 1hr aging time.

Abstract: The process of fabricating reliable materials according to efficient usage has become one of the most vital concerns. In this paper, the fabrication of functionally graded materials (FGMs) is the target using a specified application of an internal combustion engine piston model to achieve such a gradient. With a convenient rotational speed under the concept of centrifugal casting technique, the required gradient piston was successfully produced from two pure aluminum alloys A336 and A242 by such a new mechanical technique for having the required gradient. The percentages of internal ingredients, mainly, silicon were controlled axially through the piston. Chemical composition analysis, micro-hardness and wear resistance tests were performed to check the gradient and to know the difference between mechanical properties for each piston portion from its top combustion chamber to its skirt, achieving compatible results through performed tests. Obvious opposite direction gradient of silicon content to copper content appeared. Micro-hardness, wear resistance and coefficient of friction values showed a successfully gradient in the axial direction of the piston model.

Abstract: This paper deals with three types of triplex steel, where containing 25 to 28 wt.% manganese, 0.8 to 0.89 wt.% Carbon, 9.9 to 11.11 wt.% Aluminum, and with different Nickel content. Two types contain Ni in range of 0.9 to 2 wt.% and third type doesn’t contain Ni. The precipitation of Nano-size kappa carbides is the most proper technique used for this objective. It is expected that inter-metallic strengthening mechanism should act more effective in promoting the strength of Triplex steel with ductility. From this point of view, this research was designed to study the effect of inter-metallic inductive alloying element as Nickel on promoting of the strength and ductility of the high aluminum containing high manganese steel. Optical microscope, scanning electron microscope (SEM) and X-ray diffraction (XRD) were used to detect of inter-metallic precipitates through steel investigated ranged in Nickel from 0 to 2 wt.%. Mechanical and strain hardening properties were determined in the steel investigated after different regimes of heat treatment. It was found that Ni₃Al inter-metallic compound provides the austenite matrix with good strength and ductility, depending on the ageing time. Further deterioration was obviously observed in the steel investigated as increasing the ageing time, attributing to coarse structure occurrence.

Abstract: In this work, molecular dynamics (MD) simulation was utilized in relation to access the thermal conductivity of UO2, PuO2 and (U, Pu)O2 in temperature range of 500–3000 K. Diffusion study on mixed oxide (MOX) was also performed to assess the effect of radiation damage by heavy ions at burnup temperatures. Analysis of the lattice thermal conductivity of irradiated MOX to its microstructure was carried out to enhance the irradiation defects with how high burnup hinders fuel properties and its pellet-cladding interaction. Fission gas diffusion as determined was mainly modelled by main diffusion coefficient. Degradation of diffusivity is predicted in MOX as composition deviate from the pure end members. The concentration of residual anion defects is considerably higher than that of cations in all oxides. Depending on the diffusion behavior of the fuel lattice, there was decrease in the ratio of anion to cation defects with increasing temperature. Besides, the modern mixed oxide fuel releases fission gas compared to that of UO2 fuel at moderate burnups.

Abstract: This study investigates the suitability of crushed polyethylene terephthalate (PET) waste, which is a non-biodegradable generated waste as a substitute material for natural sand in the production of hollow sandcrete blocks for sustainable infrastructure. The physical properties of the natural sand and crushed PET aggregate materials used in the batching mixtures which include; specific gravity, water absorption, bulk density and particle size distribution were determined. While the mechanical properties; density, compressive strength, and the water absorption of the produced hollow sandcrete block samples using the granulated PET aggregate as a replacement for natural sand at 5%, 10%, 30% and 50% were studied. Results showed that the PET aggregates exhibit lower physical properties compare to natural sand. The addition of the finely granulated PET aggregates as a partial substitute for natural sand gradually reduced the density of the hollow sandcrete blocks as the replacement increases in the mix. However, the water absorption tendency of the sandcrete blocks reduces as the percentage dosages of PET aggregate increases. A similar reduction trend was noticed in the compressive strength of the produced hollow sandcrete blocks. The results showed a strength reduction from 2.564 N/mm² to 1.140 N/mm² for sandcrete mixes containing 5% and 50% PET, respectively, and 2.991 N/mm² to 1.510 N/mm² for sandcrete mixes containing 5% and 50% PET, respectively as the percentage substitution of sand with PET increases for 7 and 28 days curing age. The obtained results indicate the possibility of using granulated PET aggregate at 5% sand replacement in production of hollow sandcrete blocks of comparable strength to conventional sandcrete blocks. This will help to promote green production for sustainable infrastructure and reducing the menace of plastic pollution in line with the UN Sustainable Development Goals.

Abstract: The mould-ability of concrete into intricate forms and the versatility of its constituent materials has made concrete to be the most preferred construction material. However, in developing nations such as Nigeria, poor quality of concrete is listed among the common causes of building collapse. Thus, this study investigated the effects of chemical compounds of four commonly used local ordinary Portland cement brands on the compressive strength of normal concrete. The cement was labelled brands A, B, C, and D, respectively, while all the other constituent materials remained constant in this study. The HACH DR 200 direct reading spectrophotometer method was used to analyze the composition of the oxide in each of the cement samples, while the Bogue composition formula was used to estimate the compound compositions of the cement samples. A designed mix proportion of 1:2:4 (cement: sand: granite) at water-cement ratio (w/c) of 0.6 was used to produce the concrete with an expected target strength of 25 N/mm². Also, the initial and final setting time of the cement samples and the workability of the concrete mixes were determined. Forty-Eight (48) numbers cube samples were cast and tested for compressive strength at 3, 7, 14, and 28 curing days, respectively, using a 150 mm concrete cubes. The result shows the setting time of the cement samples to be within an acceptable period. Also, results indicated that the cement brands have a significant percentage of Tricalcium Silicate (C₃S) content and low percentage Dicalcium Silicate (C₂S) content responsible for faster hydration rate and higher early strength gain of the concrete. However, it was observed that a higher percentage of Tricalcium aluminate (C₃A) leads to higher strength gain from 7 to 28 days of curing age.

Abstract: The current research presents a novel porous tibia implant design based on porous structure. The implant proximal portion was designed as a porous rhombic dodecahedron structure with 500 μm pore size. Finite element method (FEM) was used to assess the stem behavior under compressive loading compared to a solid stem model. CATIA V5R18 was used for modeling both rhombic dodecahedron and full solid models. Static structural analysis was carried out using ANSYS R18.1 to asses the implant designs. The results indicated enhanced clinical performance of tibial-knee implants compared to the solid titanium implant via increasing the maximum von-Mises stresses by 64% under the tibial tray in porous implant which reduce stress shielding. Also, the maximum shear stress developed in bone/implant interface was reduced by 68% combined with relieving the stress concentration under the stem tip to relieve patients' pain. Finally, porous implants provide cavities for bone ingrowth which improve implant fixation.