Materials Science Forum Vol. 1021

Abstract: The current study investigated the electrical properties of Cadmium Telluride (CdTe)by using the first principle of density functional theory (DFT). The nanocrystals suggested being varied constantly over the network systematically so that the lowest value for energy is obtained, through which stability is obtained and through this exceptionality, the measurements of the properties are in their exact state. The conduction and the valence bandwidths were also studied. The investigations targeted the “highest occupied molecular orbital” (HOMO) [Ionization Potential], and the “lowest unoccupied molecular orbital” (LUMO) [Electron Affinity]. Total and cohesive energies, the atomic iconicity, electron affinity, energy gap (Eg), and the density of states (DOS) for 8, 16, 54, and 64 atoms. The results showed that the shape of the conduction and valence affect the crystal groups significantly, and the energy gap exhibited very close results to their practical counterparts that were previously conducted. When the lattice constant decreases the modulus of bulk and the waves of sound speed increase with the increase of the core atoms number. Subsequently, the applied pressure increases the Plasmon energy and bulk modulus. The key of study is to inspect if using materials in their nanoscale state gives special physical, electronic and optical properties through which devices are manufactured with high efficiency in the solar cell industry. Where the compound becomes a point of a sleeve, and the fluorescent peak shifts across the visible field to the UV field. This was obtained by controlling the size of the compound in 54 and 64, at which the energy gap showed an increase, which would make it more preferred to stimulate the electron from the valence band to the conduction band.

Abstract: Portland cement-based grouting compound is called GP-Grout employed to produce a sort concrete as a replacement from the weight of cement in mixes and strengthened with steel nails to enhance the mechanical properties. GP-Grout replaced cement by 25%, 50% and 75% while the steel nails as locally steel fibres were used with 0.25%, 0.5%, 1%, 2 % and 3% by volume of concrete. GP-Grout powder enhanced mechanical properties of ordinary concrete especially; the compressive strength by increasing from 34 to 70 MPa as well as other properties including tensile and flexural strength with clear improvement by adding the steel nails at a ratio of 3% by volume and the results were 5.67, 9.81 MPa respectively.

Abstract: Roller compacted concrete (RCC) is a special type of concrete with zero or even negative slump consistency. In this work, it had aimed to produce an RCC mix suitable for roads paving with minimum cost and better engineering properties so, different RCC mixes had prepared i.e. (M1, M2, M3, and M4) using specified percentages of micro natural silica sand powder (SSP) as partial replacement of (0%, 5%, 10%, and 20%) by weight of sulfate resistant Portland cement. Additionally, M-sand, crushed stone, filler, and water had been used. The results had obtained after 28 days of water curing. The control mix (M1) had satisfied the required f ‘c with accepted results for the other tests. M2 mix with SSP of 5% had achieved the highest results. The f ’c for sawed cubes of (10*10*10) cm had increased by 2.26% and 3.16% when tested in directions (ꓕ and //) to the direction of loading respectively. R results for sawed prisms of (38*10*10) cm had increased by 8.78% and 8.43% when tested on top and bottom faces respectively. The density had increased by 1.04% while the absorption and volume of permeable voids had decreased by 8.11% and 7.83% respectively. The UPV results had also increased by 2.44% and 0.81% for cubes and prisms respectively when compared to the control mix. M3 mix with SSP of 10% had also achieved satisfactory results when compared to the control mix.

Abstract: Material selection is one of the vital and critical steps in the mechanical design process. In recent times, various tools based on the multi-criteria decision-making process are used successfully to cope with such complexity in material selection. .This work provides appropriate methods and tools to find the optimum thermoplastic polymer reinforced natural fiber composites. The material selection applied using a decision-making model that consists of the „Technique for Order of Preference by Similarity to Ideal Solution“ (TOPSIS) and „Vlsekriterijumska Optimizacija I Kompromisno Resenje“ (VIKOR) methods in order to rank of the materials according to applied criteria. Analytical Hierarchy Process (AHP) method was performed in order to determine the weighting of the material properties or criteria. Rank the materials were gained by using ranking scores as results of the methods use. The results offer that the best polymers were found to be the LDPE and Nylon 6,6. It was proved that the multi-criteria decision-making model is an application for solving complex material choice decision problems. This model can be applied to other engineering applications with any number of alternatives and criteria for material selection.

Abstract: Non-Destructive methods have greater advantage in assessing the homogeneity, compressive strength, corrosion of rebars in concrete etc. of damaged structures. The aim of the present study is to assess the existing building, which is 41 year old, in the Technical Institute of Amara affiliated with the Southern Technical University, Maysan, Iraq. The research focus on the assessment of the concrete strength and the inspection of the damages in the building. Besides the visual inspection, the ultrasonic pulse velocity and schmidt hammer were used as a non-destructive test method for testing of 30 columns and 15 beams for a building consisting of three floors. The concrete compressive strength was estimated by using SonReb method. The equations proposed by Gasparik, 1984, Di Leo & Pascale, 1994, Arioglu et al., 1996, Cristofaro et al. (EXP), 2020 and Cristofaro et al (PW), 2020 were used for assessment the compressive strength of oncrete. The non-destructive test results indicated that the average strength of the structural elements greater than the design compressive strength of the tested elements. Therefore, the building can be considered structurally is safe.

Abstract: The Cu- Al-Ni shape memory alloys have numerous industrial applications such as actuators, Cryofit hydraulic couplings, fire safety valves ,etc. while the parts that soaked in the sea water suffer severe corrosion that lead to worsening in the properties of the alloys. In the current research, the effect of adding titanium on corrosion behavior of the shape memory alloys (Cu-13wt. %Al-4wt. %Ni) were studied. Titanium was added in different weight ratios (0.4, 0.8, and 1.2 wt.%) to the base alloy. The alloys were prepared using powder metallurgy, whereby the alloys were sintered with two stages of heating under Argon atmosphere, at 550°C for (120 min.) and 950°C for (180 min.)respectively. All the sintered samples are solution treated by heating the samples at 900 °C for (60 min.) followed by rapid quenching in ice water at ( 3 ~ 6) °C. After that aging heat treatment has been done for quenched samples at 200 °C for (30 hrs.) followed by rapid quenching in iced water. Several tests such as microstructures observation and phase analysis using scanning electron microscope, energy dispersive spectrometer, and X-ray diffraction analysis have been done. Further , Corrosion behavior for all samples in aged conditions in 3.5%NaCl solution have been performed. Corrosion test results have showed that the highest corrosion resistance was found in the addition of (1.2 wt.% Ti) which give the lowest corrosion rate (0.003 mpy) in 3.5% NaCl solution . Noted that the corrosion rate of base alloy was (9.021)mpy. EDS analysis showed chemical composition of the aged surface and also mapping images for the distribution of Cu, Al, Ni, and Ti elements on the surface. Phases formed on aged samples conditions are α-Cu and AlCu3.

Abstract: Copper oxide (CuO) nanoparticles were prepared by the sol-gel method, by the reaction of copper chloride and ammonium hydroxide as procurers. Nanopowders are annealing at different temperatures (100 °C, 200 °C, and 600 °C) for 120 min and confirmed the monoclinic phase by X-ray diffraction analysis of the metal oxide with lattice parameters a = 4.694 Å, b = 3.456 Å and c = 5.165Å for annealing temperature 400°C. Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and UV-Visible Spectroscopy spectrum was used to determine the structure, average crystallize, and morphology. We found increasing in size and energy gap (Eg) from (62.95 nm to 106.84 nm) and from (1.72 eV to 1.49 eV), when annealing temperature increasing from 200 °C to 600 °C, respectively.

Abstract: In the present work, an experimental investigation has been made of a dry sliding wear rate for aluminum, aluminum alloy (Al-Fe-V-Si), bronze, stainless steel 304 and structural steel ASTM A36, using a pin-on-disk apparatus under the effect of sliding speed and time at constant load. The materials were tested on two types of abrasive surfaces with a grit surface of 24 and 36. The applied load was equal to 2500 grams and the same load was used for all of the pins that were tested. The relative wear was indicated by the loss in length and loss in mass. The results show that the wear rate will directly proportional with sliding speed and time, and the stainless steel has less wear rate than the other materials.

Abstract: The study of fatigue behavior of aluminum alloy 6063 exposed to periodic fatigue stresses was studied in laboratory conditions under the two conditions of the presence of the first indentation in the first test, then the presence of the phenomenon of erosion in the second test resulting from the projection of pure water Jet on samples of the same metal used in The first test. The purpose of these tests was to estimate the practical life of these samples and the resulting accumulation by using upward and downward variable stresses. A mathematical model was built to calculate the life of the samples in the above conditions, and the results of the estimated life of the samples calculated by the model showed a large convergence with the results of the estimated life of the samples practically calculated. So this mathematical model can be used to estimate the life of samples made of different minerals under these same conditions, after knowing the (S-N) curve for each metal and the amount of the value of the fatigue notch factor (Kf), which can be calculated from special tables without referring to performing practical tests for them.