Advanced Materials Research Vol. 1160

Abstract: Nowadays, the use of additions in the concrete blends to improve its behavior is increasingly noticeable. The present research describes the effect of adding a polymer to a concrete blend of materials belonging to the zone of Morelia, Mexico. The polymer is an organic starch gained commercially, and it was added at a 2 percent per cement weight. The concrete’s physical and mechanical performance was monitored against a control blend to quantify any improvements. Destructive and non-destructive tests were performed. The addition of a polymer improved substantial concrete performance. Numerical models found correlations among the tests made, a technique by machine learning for establishing predictive models to assess the results.

Abstract: This research aims to investigate the effect Si on microstructures and mechanical properties of normalized pressure vessel steel A517 Grade Q. The Si contents were varied from 0.5, 0.9, 1.2, and 1.6. The normalizing process was carried out at 920 °C in 10 minutes. The microstructures were characterized by optical light microscope and Scanning Electron Microscope (SEM), and The mechanical tests were conducted by hardness, tensile, wear, and impact testing machine. The microstructures and mechanical properties were investigated. The results of the microstructures test show that the phases of the material are bainite and ferrite. The increase of Si content will refine and distribute the bainite phase in the ferrite matrix. The mechanical tests show that the Si content will affect the mechanical properties such as hardness, tensile strength, ductility, wear resistance, and toughness. The Increase of Si content from 0.5 up to 1.2 will increase the hardness, tensile strength, and wear resistance, and will decrease the elongation and toughness of the normalized pressure vessel steel A517 grade Q. The mechanical properties seem constant from 1.2 up to 1.6 of Si.

Abstract: High strength concrete (HSC) characterized by high compressive strength but lower ductility compared to normal strength concrete. This low ductility limits the benefit of using HSC in building safe structures. Nanomaterials have gained increased attention because of their improvement of mechanical properties of concrete. In this paper we present an experimental study of the flexural behavior of reinforced beams composed of high-strength concrete and nanomaterials. Eight simply supported rectangular beams were fabricated with identical geometries and reinforcements, and then tested under two third-point loads. The study investigated the concrete compressive strength (50 and 75 N/mm²) as a function of the type of nanomaterial (nanosilica, nanotitanium and nanosilica/nanotitanium hybrid) and the nanomaterial concentration (0%, 0.5% and 1.0%). The experimental results showed that nano particles can be very effective in improving compressive and tensile strength of HSC, nanotitanium is more effective than nanosilica in compressive strength. Also, binary usage of hybrid mixture (nanosilica + nanotitanium) had a remarkable improvement appearing in compressive and tensile strength than using the same percentage of single type of nanomaterials used separately. The reduction in flexural ductility due to the use of higher strength concrete can be compensated by adding nanomaterials. The percentage of concentration, concrete grade and the type of nanomaterials, could predominantly affect the flexural behavior of HSRC beams.

Abstract: A facile method was successfully developed to prepare Ternary oxynitride of iron and gallium. Initially mixed oxyhydroxides of Iron and gallium were prepared by co-precipitation method. Then this was nitrided using urea and agar in presence of ammonia at 900°C, which gave mixed cation oxynitride . This mixed oxynitride was characterized using XRD, XPS and SEM. The X-ray diffraction pattern of the Fe_x’Ga_xO_yN_z phase was refined within the cubic spinel structure (space group Fd-3m), using the fullprof program. On assuming 3⁺ oxidation state for half of iron and whole of gallium, the chemical composition of the oxynitride spinel determined by the X-ray analysis is Fe₂GaN₂O₂. The refinement using these parameters resulted in a good fit to the observed diffraction data, with a crystallographic R factor of 5.92. This ternary oxynitride of iron and gallium is a novel material which can give unique optical and magnetic properties.

Abstract: Hafnium and Hydrogen co-doped indium oxide films (IHFO:H) were prepared by radio frequency magnetron sputtering technology. The effect of hydrogen-donor dopant on the structural, optical and electrical properties of the films was investigated systematically. The resistivity of the IHFO:H film decreased by 2.4×10^-4 Ω cm and the mobility improved by 8.2 cm²/Vs compared with Hafnium oxide doped indium oxide film. Employing the IHFO:H film as an electrode for a solar cell can improve efficiency.

Abstract: An energy and communication efficient FSS is presented for equivalent model of ESG with hard coating. An FSS with second order band-pass response has been realized by full wave 3D simulations and results have been imitated using an equivalent circuit model to calculate the value of lumped elements. The design is composed of three cascaded FSSs with two glass layers of 6 mm each in between. Due to this topology the transmission of useful RF/microwave signals has been improved for a wider bandwidth, increased thermal insulation, stable frequency and polarization at oblique incidence and security for WLAN at 2.45 GHz.

Abstract: The electrocatalytic ammonia synthesis using water (along with nitrogen) as a hydrogen source is proposed as an alternative green and clean technology to the energy-intensive and CO₂-emitting process (Haber-Bosch) for ammonia production. Besides, a selective electrocatalyst for ammonia synthesis versus the competing hydrogen evolution remains elusive. This study aims to investigate the electrocatalytic activity of non-noble metal Co and Fe-free perovskite oxide-based composite cathode (La_0.75Sr_0.25Cr_0.5Mn_0.5O_3-δ-Ce_0.8Gd_0.18Ca_0.02O_2-δ) towards ammonia synthesis from H₂O and N₂. The electrocatalyst was synthesized via a sol-gel process and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Ammonia was successfully with a maximum formation rate of 2.5 × 10^-10 mol s^-1 cm^-2 and Faradaic efficiency of 0.52% at 400 oC and applied voltage of 1.4 V. The results demonstrated that the proposed non-noble metal-based electrocatalyst is a promising material for the carbon-free ammonia synthesis process.

Abstract: The processing of palm oil from the fruits of the African oil palm generates an increasing amounts of solid waste. The production of beneficial products for various applications from the oil palm wastes would reduce the amount of unwanted materials produced and contribute to a healthier environment. In this research, fractions were derived from the filtrate of the oil palm deseeded fruit head ash by fractional crystallization. Their physicochemical properties, cation, and anion compositions were determined by standard methods. Three hygroscopic oil palm ash fractions, namely crystals, anhydrous, and sediment, were obtained from the filtrate of the soaked ash. The crystals fraction showed significantly higher mean values than the anhydrous and sediment in conductivity and total organic matter (p<0.0001 each), salinity (p<0.01 and p<0.0001), and total organic carbon (p<0.01), while anhydrous had higher total dissolved solids than the crystals (p<0.01) and sediments (p<0.05). pH and melting points for the crystals and anhydrous compounds were similar (11.07 and <330) and higher than that of the sediment (10.29 and 284.2). Compared to the crystals, anhydrous fractions reveal significantly lower values in iron, phosphate (p<0.01 individually), zinc, chloride, nitrate, and sulphate (p<0.05 each), while sediments had significantly higher zinc (p<0.05) and nitrate (p<0.0001) and lower iron, chloride (p<0.05 each), sulphate and phosphate (p<0.0001 respectively) mean values. From this study, the isolation of three fractions from the oil palm empty fruit bunch ash with different physicochemical properties and ionic compositions was achieved. These fractions may serve as useful resources for utilization in various fields of research and production processes.

Abstract: In this research, a method is presented for predicting macroscopic plastic flow behavior of a quench and partitioning (Q&P) steel using data of nanoindentation experiments.The method is based on Tabor’s model in which nanohardness values obtained with indenters of different angles to be connected to the flow behavior of the indented material. The process consists of two steps: (i) the macroscopic flow relation of each microphases assessed based on the characteristic strain and constraint factor, (ii) the total flow curve of the steel extracted through an isostrain manner. A rationally successful prediction of the macroscopic plastic flow of the Q&P steel is obtained from the constituent phases properties due to consideration of the indentation size effect and application of a rule of-mixture. Eventually, the accuracy of the estimation is verified by comparing the predicted stress-strain curve to the tensile curve obtained from a standard bulk sample.

Abstract: Electron beam welding produces very narrow and deep penetration therefore it finds application where welding of thick materials is required. AISI 321 is susceptible to intergranular corrosion when it is used in high temperature and harsh conditions, owing to the Titanium depletion in the weld zone. However, the heat affected zone formed in electron beam welding extends to a narrow region across the weld pool. In the present study electron beam welding of austenitic 321 stainless steel is done to examine the mechanical and metallurgical properties of the joints. Microhardness tests along and across the weld bead were carried out. Tensile and impact tests were performed to analyze mechanical properties. The microstructures of the weld zone, fusion zone and base metals were also captured. Skeletal ferrites were seen in the weld metal. The aging treatment of 700°C for 24 hours which resulted in a change in morphology of the grains from skeletal to vermicular and promoted the formation of Ti-rich carbides on the grain boundaries. The maximum impact toughness at sub-zero temperature i.e. -40°C was recorded as 129.3 J in as-welded samples and it got reduced to 119.5 J after aging treatment. The average ultimate tensile strength was 582 N/mm² and it got decreased to 481 N/mm² after aging treatment.