Band 30, Heft 1

In this paper, an attempt is made to describe the method that combines the results obtained from nanoindentation experiment with finite element simulation to determine or establish the elastic-plastic properties of a super-hydrophobic anti-icing coating. The nanoindentation test was conducted and elastic properties of the coating, to include elastic modulus and hardness were obtained. The plastic properties, to include yield stress, monotonic strength coefficient and monotonic strain hardening exponent, were obtained using an inverse, iterative method of experimental measurement in synergism with finite element simulation. This approach, which is a combination of experimental data obtained from the nanoindentation test and results obtained from numerical finite element simulation, was found to be effective for determining mechanical properties of the chosen coating.

Submerged arc welding (SAW) has been performed using slag-fresh flux mixture on duplex stainless steel plates. Experiments were performed by recycled slag-fresh flux mixtures with iron powder; iron powder is mixed to maintain and enhance the weld strength. The effect of composition variation of slag-fresh flux mixture on weld bead geometry parameters have been investigated quantitatively. Weld bead characteristics viz. bead width; bead height; penetration area; reinforcement area, form factor and dilution were observed by metallography operations for each experiment. For varying the composition of slag-fresh flux mixture, mixture design technique; Scheffe Quadratic Model (SQM) was used. Empirical relations were developed for weld bead characteristics in terms of fresh flux, slag and iron powder and statistically checked for significance. Finally, recycled slag-fresh flux composition was optimized using desirability approach.

This paper deals with the design and optimization of a differential capacitive micro accelerometer for better displacement since other types of micro accelerometer lags in sensitivity and linearity. To overcome this problem, a capacitive area-changed technique is adopted to improve the sensitivity even in a wide acceleration range (0–100 g). The linearity is improved by designing a U-folded suspension. The movable mass of the accelerometer is designed with many fingers connected in parallel and suspended over the stationary electrodes. This arrangement gives the differential comb-type capacitive accelerometer. The area changed capacitive accelerometer is designed using Intellisuite 8.6 Software. Design parameters such as spring width and radius, length, and width of the proof mass are optimized using Minitab 17 software. Mechanical sensitivity of 0.3506 μm/g and Electrical sensitivity of 4.706 μF/g are achieved. The highest displacement of 7.899 μm is obtained with a cross-axis sensitivity of 0.47%.

The use of agricultural wastes as additives for other valuable products has been the focus of many research efforts because of their availability, inherent properties, and environmental friendliness. Palm kernel shells (PKS) and coconut shells (CNS) are agricultural solid end products obtainable from the cracking of their fruit nuts. In this study, PKS and CNS were used to produce abrasive sandpaper following established procedures. The mechanical properties of the sandpaper produced were established. Material for application in abrasive operations must exhibit maximum hardness and compressive strength, minimal wear rate, water absorption, and density. Results showed a 20% and 25% increment in specimen hardness values for PKS and CNS respectively in samples with polyester resin content weight composition range of 7.8–22.2% based on sieve size of 250 μm. Similarly, 29.23% and 32.44% increment for PKS and CNS respectively was recorded for a sieve size of 420 μm. Samples with a high percentage of binder exhibit better wear characteristics for both PKS and CNS for the investigated parameters. As the percentage weight composition of PKS and CNS samples increases in the abrasive sandpaper composites, the water absorption properties decrease for both 250 μm and 420 μm sieve sizes. Samples compressive strength increases as the percentage weight composition of binder increases over a range of 7.8 to 22.2% for both 250 μm and 420 μm sieve sizes studied. Similarly, as the percentage weight composition of PSK and CNS increases, the sample exhibit high density for both sieve sizes. These characteristics affirmed the suitability of the abrasive composites made with PKS and CNS for frictional applications.

CP-Ti G2 has become the preferred biocompatible material for various devices mainly used in orthopedic and dental implants and it is also used in aviation and aircraft. While CP-Ti G2 deals with good ductility, higher stiffness, and fatigue resistance. The novelty of present research work was attentive to the effect of WEDM factors on MRR. After machining, surface topography was examined through SEM. MRR was modeled through ANOVA to analyze the adequacy. It was observed that POT, POFT, PC, and SGV most significant factors. The WEDM factors have also been significantly deteriorating the morphology of machined samples in the form of craters, debris, and micro cracks. A multi-objective optimization ‘desirability’ function hybrid with a supervised machine learning algorithm was applied to obtain the optimal solutions. The results show a good agreement between actual and predicted values.

The main problem associated with high thickness carbon steel plate's narrow range or “V” groove welding in conventional welding processes is the sagging of the molten pool due to gravity, which in turn leads to defects formation and deteriorates mechanical properties. This problem could be overcome by the rotating arc gas metal arc welding (RA-GMAW) technique. This investigation aims to evaluate mechanical properties and metallurgical characteristics of high thickness IS2062 Gr-B carbon steel joints welded by RA-GMAW technique. The experimental results show that RA-GMAW joint exhibited higher (598 MPa) tensile strength, higher hardness (220 HV) at weld metal region, and lower impact toughness (137 J) than the unwelded base metal. This is due to the presence of fine acicular ferrite and widmanstatten ferrite matrix mixed with fine lamellar pearlite microstructure in the weld metal region.

Egypt plays an important role in the consuming markets for tires all over the world. There is an urgent need to get rid of them in an economic and environmental way since it is considered as a harmful waste if burnt. The World trend is directed towards the improvement of new techniques to insert the rubber into useful products to maximize the benefit of recycling. This research deals with the expansion of novel techniques for rubber powder recycling for various purposes in a robust construction. Recycled rubber particles (RRP) are mixed with ordinary Portland cement (OPC) using various water to binder ratio (W/B) at 0.3 and 0.4. The Fourier transform – infrared (FT-IR) spectra is measured for RRP. The compressive strength (C.S) is investigated for the rubberized cement pastes at 1, 3, 7, 14 and 28 days. The results aimed to enhance the compressive strength of rubberized cement pastes through improving the bonding strength between RRP and OPC by using fine particles of RRP. Maintaining the compressive strength in the highest levels with different RRP percentages in addition to the vibrational damping property of RRP gives rubberized cement pastes the advantage to replace ordinary concrete in most construction applications.

This study investigated the structural response of granular and asphaltic overlayment of rail track considering the linear viscoelastic behavior of asphalt. The calculation of the tensile strains at the bottom of the asphalt layer, the compressive stresses at the top of the subgrade layer, and the service life of the granular and the asphaltic overlayment rail track were conducted using the KENTRACK software. Furthermore, the sensitivity analysis by changing different factors was studied in this paper. The results of this study indicate that the asphaltic overlayment rail track structure has a much longer predicted service life than the granular rail track. It was also shown that the sub-grade compressive stress is more sensitive to the change in subgrade modulus than the change in ballast-sub-ballast-asphalt layer thickness and the change in binder type, respectively. In addition, the asphalt tensile strain is more sensitive to the change in asphalt layer thickness than the change in subgrade modulus and the change in binder type, respectively. These findings also enhance our understanding that subgrade compressive stress and asphalt tensile strain in the asphaltic overlayment track are more sensitive to the change in asphalt layer thickness than the change in binder type.

One of the most important problems associated with the combat use of unmanned aerial vehicles remains to ensure their high survivability in conditions of deliberate countermeasures, the source of which can be both ground-based air defence systems and fighter aircraft. For this reason, the study and optimization of evasive manoeuvres of an unmanned aerial vehicle from an enemy aircraft attack remains relevant. Based on the game approach, the authors of this paper propose an algorithm for guaranteeing control of the trajectory of an unmanned aerial vehicle, which ensures its evasion from an enemy air attack. The study of the influence of tactically significant indicators of the manoeuvrability of an unmanned aerial vehicle on the effectiveness of the evasion manoeuvre was carried out. The model predictions are presented, reflecting the degree of influence of unmanned aerial vehicle manoeuvring capabilities on achieving a positional advantage when solving the problem of evading air enemy attack.

Waste control is a big challenge in industries. The aim of this study is to control degradation of farm structure using rice husk as corrosion inhibitor in pig dung, poultry dung and urea solution environment. The rice straw was subjected to phytochemical analysis. The four variables: rice straw, Pig dung, urea and poultry dung solutions were used to determine the best approach to reduce the corrosion rate of galvanized steel used for farm structures. Time variation used was 3–12 days. The result from the phytochemical analysis showed that rice husk has constituents of a good inhibitor. The result from the variables’ mix in S1: A: 40 cm 3 ; B: 40 cm 3 ; C: 10 cm 3 and D: 10 cm 3 has the highest inhibition efficiency of 88.59%. The SEM result from the best combination showed that passive film was formed which was attributed to the adsorption via rice straw extract. The rice straw used in this study was an effective inhibitor. It is an agricultural waste that was converted into a viable process which is of economic value.

In the present investigation, a new method is proposed to study the AZ30 flow curve at elevated temperatures and various strain rate. Experiments were carried out with the goal of obtaining flow curve of AZ30 at three different temperature and strain rates by using the ring test method. The presented work aims to develop a model using genetic algorithm for AZ30 flow stress prediction during different test conditions. The Santam machine was implicated that was able to perform experiments by controlling both the position and load modes. At each temperature and strain rate the isothermal test was performed respectively. In the present investigation for three varios temperatures and strain rates, 54 ring compression tests were carried out with different levels of reduction in height. Then each specimen was water cooled quickly to investigate the microstructure of AZ30 magnesium alloy by using optical microscope. The model used in the present study was able to predict the flow curve with an 2.3% accuracy. This model has excellent potential to be employed in various industry applications.

Investigation on the hot deformability and workability of stir cast 6 wt.% steel particles reinforced aluminium 6063 matrix composites was undertaken in this study. Flow stress – strain curves generated from hot compression tests performed at strain rates of 0.01, 0.1, 1, and 10 s −1 , and temperatures between 200–400°C, were used to study the flow behavior of the composite, while processing map developed from analyses of the deformation data, was used to establish the deformation mechanisms and processing safe zones for effective workability. Flow stress oscillations were observed to be prevalent at lower deformation temperatures and strain rates; largely due to the settling of reinforcement particles at grain boundary vicinities, rather than a homogeneous distribution. Also, the flow behaviour was largely strain rate insensitive. The dominant flow mechanism based on the flow stress patterns, processing map and microstructural validation was established to be dynamic recovery. Safe regions for processing based on Murty's and Gegel's criteria established the safe processing zones to be ~270–400°C at 0.01–1.0 s −1 and 380–400°C at 10 s −1 . Deformation processing was unsafe at 200–260°C at 0.01–1.0 s −1 and between 200–380°C at 1.0–10 s −1 .

The plasma electrolytic method of oxidation (PEO) is a technique that is increasingly being used in industry to produce protective coatings and other surface treatments. The emphasis is then placed on the dielectric breakdown that repeatedly occurs across the surface of the workpiece. There is significant potential for more effective process control. Key study areas include the interrelation of electrical conditions, electrolyte composition, coating microstructure, and growth rates. With specific goals in terms of coating performance and energy efficiency, an attempt is made to identify key points that are likely to simplify this. The research aims to identify the optimized range of input parameters when the oxide layer is formed using the DC supply in the silicate-based electrolyte on Al 6061 substrate. For developing an oxide layer on Al 6061, a silicate-based electrolyte containing Na 2 SiO 3 (10g/L), KOH (2g/L), and KMnO 4 3 (g/lit) is applied. At the optimal parameter of DC supply with 190 V and 1.5 A, the maximal adoption of Mn particles was observed to be 34 percent.

The use of supplementary cementitious materials like crushed glass, steel slag, and silica fume at an acceptable level has resulted in many advantages such as reduction of the waste solid materials and production of eco-friendly material. Moreover, the inclusion of fibers for reinforcing cementitious matrix can improve its properties overall. Therefore, this research has been divided into two phases. The first phase has included the production of green reactive powder mortar and the investigation of its properties. The second phase has involved the incorporation of the micro steel fibers to green reactive powder mortar with different amounts. The results have indicated that the use of the crushed glass, steel slag, and silica fume by 8, 12, and 10% as a partial replacement of cement with suitable chemical admixture gives a great reduction of cement by 30% from the total cementitious amount used in reactive powder mortar and greater values of strengths for reactive powder mortar. The addition of micro steel fibers by 1, 1.5, 2, and 2.5% improves the dry bulk density, ultrasonic pulse velocity, compressive strength, flexural strength, and tensile strength of green mortar. The best increase has been observed at green reactive powder mortar (GRPC) containing 2 % of micro steel fibers.

In Nigeria, sawdust is continuously generated in large quantities as waste but majorly under-utilised, a situation which causes serious environmental problems and health hazards when managed improperly. This work focussed on production and assessment of hygrothermal properties of solid core sandcrete blocks in which sand is partially replaced with sawdust at 0%, 10%, 20%, 30%, and 40% loading levels. Experiments were conducted on block samples made with untreated sawdust (USD) and on those similarly produced but with treated sawdust (TSD). The results showed that the blocks with USD content are capable of decreasing wall heat transmission load and improve energy efficiency of building envelopes better than their counterparts produced with TSD. In terms of compliance with standard bulk density and water absorption requirements, incorporation of USD or TSD at 20% or 10% level respectively, was found to be optimum for partial sand substitution in the studied block samples in order to suit the functional requirements of building structure and interior space. Since sawdust is cheaply and commonly available in vast amount, utilising it in sandcrete block production is a promising way of minimising its disposal problems while enhancing the development of safe, affordable, and sustainable housing.

This work aims to investigate the mechanical behavior of steel-plated structures under a raking incident and to quantify the effect of the mesh size in nonlinear finite element (NLFE) analysis. To conveniently comprehend nonlinear phenomena, i.e., the grounding which takes place in this work, a series of theoretical contact formulations was defined. In the main analysis, raking, which is a part of the grounding scenario, was strictly assumed as contact between a tanker, which was assumed to have thin-walled steel, and a seabed rock in the form of a solid obstruction. Designed raking scenarios were calculated using the FE method by using the nonlinear phenomena of the material behavior in the calculation. The findings of this work indicated that the possibility of expanding the recommended mesh size in FE simulation should be evaluated by quantifying the behavior of structural responses, such as energy, the force damage pattern, and acceleration, subjected to a variety of applied meshing techniques. The results concluded that a notable difference occurred when the mesh size was more than 132 mm (ratio 11 based on the plate dimension in this work), and this size is strictly recommended to be used for calculation of the element length-to-thickness (ELT) ratio. Assessment in time simulation showed that applying larger mesh sizes will reduce the simulation time but increase the maximum values of the crashworthiness parameters, i.e., energy, force, acceleration, and displacement.

Distinct materials are used for the construction of battle tanks used in defense sectors. The hull and turret of the battle tanks are made up of rolled homogeneous armor steel (also known as armor steel). The inner portions like the driver cabin and control room are covered with medium carbon steel. Hence, the dissimilar joint between these materials is unavoidable in the battle tank construction. Conventional fusion welding processes like manual metal arc welding, gas metal arc welding, and gas tungsten arc welding are preferred to join the dissimilar metals. However, the high heat input nature of these processes will create hydrogen induced cracking, high residual tensile strain, and HAZ softening, etc. To minimize these issues, solid state welding processes were adopted. In the present study, mechanical properties and microstructural characteristics of rotary friction welded dissimilar joint of armor steel and medium carbon steel was analyzed. The ultimate tensile strength of the dissimilar joint is around 775 MPa and the failure occurred at the medium carbon steel side. The impact toughness value of dissimilar joints is higher than medium carbon steel and lower than armor steel. The microstructure across the dissimilar joint has distinct features and a complex pattern was observed at the weld interface.

Rising environmental issues and huge disposal of rubber waste have resulted in an increased interest in the usage of reclaimed rubber (RR) to produce sustainable and environmental friendly applications. In this study, incorporation of butyl reclaimed rubber into carboxylated nitrile butadiene rubber (XNBR/BRR) was carried out where the loadings of each XNBR and BRR were varied. The rubber was cured with sulphur during the melt mixing using a two-roll mill. This study is aimed to investigate the applied BRR loading towards the physical and mechanical properties of the XNBRcompounds. The results appeared that the optimum cure time (T90) increased and curing rate index (CRI) showed that a faster curing reaction with the increase in the content of BRR where the T90 had an increment of 89% while the CRI was faster by 89%. As for the crosslink density which indicates the density of chains or segments in polymer network, it decreased about 20% with increasing level of BRR. Also, the compression set which refers to the ability of rubber to resist permanent deformation, had an increase of 73% as the loading ratio of BRR increased. These results were obtained due to the low molecular weight of the BRR where the high shear and temperature during the reclamation process severely breaks down the molecular chains of the BRR into shorter segments. With the results obtained, it is shown that reclaimed rubber has the potential for further development and could increase the interest of researchers all around the world in the incorporation of reclaimed rubber for footwear application.

Wire arc additive manufacturing (WAAM), a welding-based additive manufacturing (AM) method, is a hot topic of research since it allows for the cost-effective fabrication of large-scale metal components at relatively high deposition rates. In the present study, the cylindrical component of low carbon steel (ER70S-6) was built by WAAM technique, using a GMAW torch that was translated by an automated three-axis motion system using a rotation table. The mechanical properties of the component were evaluated by extracting tensile, impact toughness and hardness specimens from the two regions of the building up (vertical) direction. It is found that the tensile properties of the built material exhibited anisotropic characteristics. The yield strength and ultimate tensile strength varied from 333 to 350 MPa and from 429 to 446 MPa, respectively, (less than 5 % variation).

The present research reports improvement in mechanical performance of Copper-Tin(Cu-Sn) composites due to the addition of hard Si 3 N 4 particles as reinforcement. Two-step stir casting technique was adopted to prepare Si 3 N 4 -reinforced Cu-Sn based composites. The uniform distribution of the reinforcement in the matrix was ensured by SEM morphology and energy-dispersive X-ray (EDAX) spectrum of the developed composites. Brinell hardness test and tension test were used to estimate the hardness and tensile strength of the composite. Si 3 N 4 reinforcing materials added to the extent of 7.5% by wt. to Cu-Sn matrix enhanced hardness by 41% and UTS by 33%, YS by 29% and showed 23% decrement in ductility. Thus a comparison of Si 3 N 4 -reinforced Cu-Sn based composites with base metal has shown that considerable improvement in tensile properties such as UTS and YS and hardness if reinforcing material is added to the extent of 7.5%.

The assessment of a ship's ability to withstand environmental loads is very crucial. This research focuses on the strength assessment of 600 TEU container ship hulls against hydrostatic and hydrodynamic loads using finite element-based software. Parameter changes in the material types, hull thickness, and ship drafts were performed to compare the structural responses using deformation, strain, and von Mises stress criteria. All of the materials tested were acceptable, where the ASTM A131 Grade AH36 and ASTM A131 Grade AH32 materials have the lowest deformation values and strains. The simulation results regarding plate thickness variation, deformation, strain, and von Mises stress values were smaller as the thickness of the ship structure increased. Moreover, from the draft variation, the structural response due to environmental load was better as the draft of the ship increased.

Biocomposites have been implemented in various industrial applications. However, it is necessary to demonstrate their desired mechanical performance aspects for the near future green products. The aim of this work is to study the efficiency of utilizing both coconut and pomegranate lignocellulosic fiber as green reinforcement types for the low-density polyethylene, LDPE. Desired mechanical performance trends are investigated for the green composites including the tensile strength, tensile modulus, and elongation to break properties as a function of various reinforcement configurations. This was performed to properly optimize the reinforcement conditions to obtain desirable mechanical characteristics of such types of bio-composites for more sustainable functional attributes. Results have demonstrated that the best tensile strength for the coconut/PE was achieved at 20wt.% case with 8.2 MPa, and the best regarding this property for the pomegranate/PE was at 30wt.% with a value close to 8.3 MPa. Moreover, obvious inverse relationship between strength and strain for the coconut composite type was revealed at both low and high fiber contents. It was also noticed that the 20wt.% coconut-based composite has demonstrated the best optimal values of tensile strength and tensile modulus simultaneously. But no reinforcement condition was found for pomegranate/LDPE as an optimal for these mechanical properties concurrently.

In this work, iron oxide "gamma phase" ( γ -Fe 2 O 3 )-silver oxide (Ag 2 O) nanocomposite is prepared by a double hydrothermal method combined with Punicaceae plant extract as reducing agents. X-ray diffraction (XRD) results confirmed the presence of γ -Fe 2 O 3 and Ag 2 O and delafossite silver ferrite (AgFeO 2 ) phases. Field Emission Scanning Electron Microscopy-energy dispersive spectroscopy (FESEMEDS) results revealed nanoparticles (NPs) with a shape like a cauliflower plant. Furthermore, the anti-bacterial activity results presented high inhibition rates against Klebsiella pneumoniae , Staphylococcus aureus , Staphylococcus epidermidis , Escherichia coli , and Candida albicans . The present study exhibits a new approach to the preparation of metal oxides using a facile and inexpensive method.

Pure TiO 2 and TiO 2 -CdS composite nanofibers were synthesized through electrospinning technique. The effects of various levels of CdS loading in a TiO 2 nanofibers composite were investigated. Pure TiO 2 nanofibers were polycrystalline with an anatase phase, whereas anatase and wurtzite phases coexisted in the TiO 2 -CdS composite nanofibers, according to X-ray diffraction (XRD) measurements. Using field emission scanning electron microscopy (FESEM) and UV-Visible spectroscopy, the impacts of composite CdS nanoparticles with TiO 2 nanofibers were investigated. Pure TiO 2 nanofibers have a smooth surface with several microns in length and 21–48 nm in diameter, but when CdS nanoparticles are added, the surface becomes granular. The energy band gap (E g ) evaluated from UV-Visible spectroscopy reduced from a value of 3.70 eV for pure TiO 2 nanofibers to 1.70 eV for TiO 2 -1CdS nanofibers. Photocatalytic properties of pure TiO 2 and TiO 2 -CdS composite nanofibers were calculated by a methylene blue (MB) aqueous solution degradation under sunlight irradiation. The results revealed that TiO 2 -0.5CdS nanofibers have efficient photocatalytic activity of up to 98 % after only 60 min.

Crystallography information files (CIF) were designed formed Co x Cu 1−x Fe 2 O 4 solid solution with the substitution factor x=0 to 1 with an increment of 0.1 depending on Vegard's law by using crystallography software. The effect of the substitution factor has been studied on some parameters and properties of the Co-Cu ferrite system, such as the effect of substitution factor on the lattice parameter, the volume of unit cell, and the density of the unit cell. Also, XRD patterns were estimated by crystallography software depending on the mathematical models of XRD. The XRD results showed a slight shift in the peak position varying with the substitution factor, these are due to the change in lattice parameter caused by the substitution of ions with different ionic radii. XRD also showed an increment in peak intensity varying with the substitution factor, that's due to an increase in the concentration of Cu which led to an increase in the density of electrons.

Silver oxide nanoparticles (Ag 2 O NPs) in the aqueous colloidal state were synthesized using the green method. Aqueous silver nitrate was prepared and mixed jointly with an aqueous extract of Lawsonia inermis (henna) leaf and heated with stirring at 75 °C for 1h. Then, an aqueous colloidal solution of Ag 2 O NPs with a dark brown colour is forming. The physicochemical characterization of Ag 2 O NPs was studied using different techniques. A polycrystalline structure of (Ag 2 O/Ag) in face-centred cubic and cubic phases was revealing via grazing incident X-ray diffraction (GIXRD) patterns. Energy-dispersive X-ray analysis (EDX) spectra confirmed GIXRD results through peaks corresponding to the silver and oxygen elements making up the accurate composition of the silver oxide. UV-Vis absorbance peak of the localized surface plasmon resonance (SPR) appeared at the visible region and exhibited a blueshift at ∼425 nm with an energy bandgap ∼2.8 eV. The surface morphology and the size of the silver nanoparticles were analyzed using high resolution (FE-SEM) microscopy. FTIR spectra of Ag 2 O NPs has showed a shift in the bands compared to those produced by aqueous extract of the henna leaf (only). (0.4 molars) Ag 2 O NPs has showed excellent antimicrobial activity assays against all the pathogens microbe's strains. Henna plant extract (only) has showed poor activity compared to Ag 2 O NPs. In comparison, the inhibition zone diameter of the gram-negative Bacteria is more considerable than the gram-positive bacteria. Moreover, Ag 2 O NPs activity against Bacteria is more prominent than fungi.

In this study, porous silicon (PSi) was used to manufacture gas sensors for acetone and ethanol. Samples of PSi were successfully prepared by photoelectrochemical etching and applied as an acetone and ethanol gas sensor at room temperature at various current densities J= 12, 24 and 30 mA/cm 2 with an etching time of 10 min and hydrofluoric acid concentration of 40%. Well-ordered n-type PSi (100) was carefully studied for its chemical composition, surface structure and bond configuration of the surface via X-ray diffraction, atomic force microscopy, Fourier transform infrared spectroscopy and photoluminescence tests. Results showed that the best sensitivity of PSi was to acetone gas than to ethanol under the same conditions at an etching current density of 30 mA/cm 2 , reaching about 2.413 at a concentration of 500 parts per million. The PSi layers served as low-cost and high-quality acetone gas sensors. Thus, PSi can be used to replace expensive materials used in gas sensors that function at low temperatures, including room temperature. The material has an exceptionally high surface-to-volume ratio (increasing surface area) and demonstrates ease of fabrication and compatibility with manufacturing processes of silicon microelectronics.

Solvent-free ball milling was used to activate kaolin, a trioctahedral clay material, with diammonium phosphate[(NH 4 ) 2 HPO 4 ] to serve as a fast-acting phosphorus and nitrogen releasing fertilizer. Different tests on a mixture of 3:1 weight ratio of kaolin: (NH 4 ) 2 HPO 4 were performed to analyze the level of incorporation of (NH 4 ) 2 HPO 4 in the kaolin and the degree of liberation of NH4+ {\rm{NH}}_4^ + and PO43− {\rm{PO}}_4^{3 - } ions into solution. The experimental mill speeds were varied from 200 to 700 rpm rotational rates for a fixed period of 2 hours. Several milling periods of 1, 2, and 3 h. were studied at the fixed milling speed of 600 rpm. To explain the properties of activated materials and to understand the purpose behind the simpler disintegration of phosphorus, several analytical methods such as FT-IR, TGA-DTG and Ion chromatography (IC) were used. The proposed procedure was environmentally friendly, and it helped to maintain a balanced supply of nitrogen and phosphorus fertilizer for agriculture's long-term development by offsetting some of the existing high-cost chemical fertilizer. The results demonstrated that the mechanochemical reaction could yield an intercalated form of kaolin that is a transmitter of N and P sources in fertilizers.

Stainless steel 316L (SS316L) as a significant bio-material, their wires were used to support the PMMA matrix. Two simple and low-cost surface pretreatments for SS316L wires were performed to enhance denture impact strength: mechanical scratching (treating SS316L wires with SiC powder inside a rotating container) and electrochemical anodizing. Three mechanical scratching samples for different periods of 60, 90 and 120min were prepared. Anodizing technique conditions were: Ethylene glycol with perchloric acid as an anodizing solution, 15V supplying and graphite rod as an anode. Anodizing process involved three pretreating periods of 15, 20, and 30min. All the prepared samples had dimensions of 65 × 10 × 3 mm. SEM technique showed different morphology nature involved holes, scratches and pores with a density of 10 4 /μm 2 and a crack length of 60μm. The PMMA reinforced with scratched stainless steel 316L wire surface for 120 min presented the highest impact strength value (42 kJ/m 2 ) with (450.91%) increment. Anodizing samples showed a fluctuating behavior of samples with enhancing in the impact strength of anodizing wire for 20min of about 26.99 kJ/m 2 , which is still lower than that for scratched samples in average.

Dopamine is considered an important molecule that plays several essential roles in the human body, and herein lies the key to this paper on the electronic and optical properties of dopamine and its derivatives, such as quinone and L-dihydroxyphenylalanine (L-DOPA), using DFT and TD-DFT methods, respectively. Our findings show that dopamine has a dielectric behavior, whereas quinone and L-DOPA have semiconductor behaviors in the ground and excited states. By computing the optical properties, we disclose that the electronic transition spectrum of dopamine, quinone and L-DOPA are observed in the ultra-violet region, visible spectrum, and (ultraviolet and visible regions), respectively. Other properties, such as ionization potential, electronic affinity, hardness and softness are also calculated due to their importance in sensor applications and sensing.

This paper demonstrates the effects of multilayer coatings on the thermal conductivity of tool specimens. The experiments were conducted using copper specimens and four tool specimens with different coatings (uncoated, TiN, TiN/TiCN, and TiN/Al 2 O 3 /TiCN). An electrical furnace technique was used with the specimens isolated from their surroundings and temperatures measured at the contact surfaces. The specimens are joined securely, with a thermal insulator (glass wool) placed around them so that the heat flow is in the axial direction only. One surface of the copper specimen faces the heat source, and the opposite end of the tool specimen is exposed to room temperature. The experimental results displayed variations in the temperature distribution due to the effect of the coatings, and thermal conductivities were measured at temperatures ranging from 100°C to 300°C. The results indicated the optimum coating for tools (lowest thermal conductivity) of the four types is TiN/Al 2 O 3 /TiCN.

In the present work, the influence of plastic deformation on the properties of a 3004 Al-alloy was studied with different techniques. Crystallite size, dislocation density, defect density, micro-strain, and stored dislocation energy are presented and compared for different three techniques. Methodology Many techniques for detecting defects have been developed, such as the positron annihilation lifetime technique (PALT), the positron annihilation Doppler broadening technique (PADBT), and the Vickers hardness test (HV). Implications The positron mean lifetime value of a non-deformed sample is 173±4.8 ps, which increases until the thickness reduction reaches a 10% deformation then saturated at saturation trapping of the positron in defect states with a mean of 221±5 ps. At an S-parameter of 0.3709±0.0031, a W-parameter of 0.5885±0.0057 was obtained at zero deformation: this decreases until saturation at 10% deformation. Findings A good correlation between the three techniques is observed for mean crystallite size. A good correlation was also noted between PALT and PADBT from 0 to 10% thickness reduction. HV has good correlations with PALT and PADBT from 0 to 6% thickness reduction: then a clear difference was found from 6 to 15% thickness reduction. Originality such results confirm the fact that the used technique can effects on the obtained results in some limitations.

In this work, TiO nanostructure films were deposited via vacuum thermal evaporation at a temperature of 80°C. The TiO thin films were annealed under vacuum for 1 h at three different degrees (200, 300, and 400°C) in addition to the thin film prepared at 80°C. X-ray Diffraction (XRD) showed that all the deposited and annealed TiO films had anatase polycrystalline diffraction patterns with a predominant reflection of the (200) plane. As a result, the particle size increased with annealing temperature. Scanning Electron Microscopy (SEM) measurements showed that at the annealed temperature of 200°C, the shape of the TiO nanostructures began to change from a condensed cluster distribution to a conical shape. As the annealing temperature was increased to 400°C, all the conical shapes transformed into clear spherical shapes. The spherical shapes recorded 45 (nm) height and (20) (nm) base width. Optical measurements were performed using Ultraviolet-Visible spectroscopy (UV-Vis). The transmittance is reduced from 79.63% for the TiO sample prepared at 80°C to 71.91% for the TiO sample annealed at 400°C. The optical energy gap values decrease from 3.279 eV for the prepared TiO sample at 80°C to 3.115 eV for the TiO sample annealed at 400°C.

This study analyses the causes of rapid failure at the early stages of hot forging tools. Tool life generally refers to the number of forgings that meet the required geometry, properties and quality produced by a tool. Die failure in hot forging processes are caused by failure modes such as plastic deformation, wear and thermomechanical fatigue. This study focuses on plastic deformation failure. The practical experience was carried out in the upset forge fastener head, having a workpiece material of Ck45 alloy steel and tool made of 56 NiCrMoV7 tool material, which was forged at 950–1150°C, under an 800-ton, horizontal mechanical press. The finite element (FE) software MSC Simufact Forming 16.0 was used to simulate the process. The results showed plastic deformation occurring in the upper and lower dies because the temperature increase progressively reduced the hardness, creating softening effects during the forging process. The optimal forging temperature to form the fastener head was determined to be lower at 1000°C, saving time and cost. The FE method can be efficiently used to enhance the formation and to predict diet life.