Search results for: nano hardness nanoindentation

Authors: Asli Beyler Çi̇ği̇l, Memet Vezi̇r Kahraman

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Organic–inorganic hybrids have become an effective source of advanced materials because they combine the advantages of both the organic moiety such as flexibility, low dielectric constant, and processability, and inorganic moiety as rigidity, strength, durability, and thermal stability. By incorporating cross-linkable side chains, the hybrid materials can be made photosensitive and UV curable, which offers many advantages including low processing temperature, low equipment cost and compatibility. In this study, uv-curable organic-inorganic hybrid material, which was contained surface modified polyaniline particles (PANI), was prepared. PANI surface photografted with hydroxy ethyl methacrylate (HEMA) to produce hydroxyl groups. Hydroxyl functionalized PANI/HEMA was acrylated using isocyanato ethyl methacrylate (IEM) in order to improve the dispersion and interfacial interaction in composites. UV-curable formulation was prepared by mixing the surface modified PANI, polyethylene glycol diacrylate (PEGDA), trimethylolpropane triacrylate (TMPTA), hydrolized 3- methacryloxypropyltrimethoxysilane (hyd. MEMO) and photoinitiator. Chemical structure of nano-hybrid material was characterized by FTIR. FTIR spectra showed that the photografting of PANI was prepared successfully. Thermal properties of the nano-hybrid material were determined by thermogravimetric analysis (TGA). The morphology of the nano-hybrid material was performed by scanning electron microscopy (SEM).

Keywords: polyaniline, photograft, sol-gel, uv-curable polymer

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Authors: Wei-Hsuan Hsu, Yi-Xuan Huang

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Nanoimprint lithography (NIL) possesses the advantages of sub-10-nm feature and low cost. NIL patterns the resist with physical deformation using a mold, which can easily reproduce the required nano-scale pattern. However, the variation of process parameters and environmental conditions seriously affect reproduction quality. How to ensure the quality of imprinted pattern is essential for industry. In this study, the authors used the electrowetting technology to assist mold filling in the NIL process. A special mold structure was designed to cause electrowetting. During the imprinting process, when a voltage was applied between the mold and substrate, the hydrophilicity/hydrophobicity of the surface of the mold can be converted. Both simulation and experiment confirmed that the electrowetting technology can assist mold filling and avoid incomplete filling rate. The proposed method can also reduce the crack formation during the de-molding process. Therefore, electrowetting technology can improve the process quality of NIL.

Keywords: electrowetting, mold filling, nano-imprint, surface modification

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Authors: Majid Eslami

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Functionally graded materials (FGMs) exhibit heterogeneous microstructures in which the composition and properties gently change in specified directions. The common type of FGMs consist of a metal in which ceramic particles are distributed with a graded concentration. There are many processing routes for FGMs. An important group of these methods is casting techniques (gravity or centrifugal). However, the main problem of casting molten metal slurry with dispersed ceramic particles is a destructive chemical reaction between these two phases which deteriorates the properties of the materials. In order to overcome this problem, in the present investigation a suspension of 6061 aluminum and alumina powders in a liquid polymer was used as the starting material and subjected to centrifugal force for making FGMs. The size rang of these powders was 45-63 and 106-125 μm. The volume percent of alumina in the Al/Al2O3 powder mixture was in the range of 5 to 20%. PMMA (Plexiglas) in different concentrations (20-50 g/lit) was dissolved in toluene and used as the suspension liquid. The glass mold contaning the suspension of Al/Al2O3 powders in the mentioned liquid was rotated at 1700 rpm for different times (4-40 min) while the arm length was kept constant (10 cm) for all the experiments. After curing the polymer, burning out the binder, cold pressing and sintering , cylindrical samples (φ=22 mm h=20 mm) were produced. The density of samples before and after sintering was quantified by Archimedes method. The results indicated that by using the same sized alumina and aluminum powders particles, FGM sample can be produced by rotation times exceeding 7 min. However, by using coarse alumina and fine alumina powders the sample exhibits step concentration. On the other hand, using fine alumina and coarse alumina results in a relatively uniform concentration of Al2O3 along the sample height. These results are attributed to the effects of size and density of different powders on the centrifugal force induced on the powders during rotation. The PMMA concentration and the vol.% of alumina in the suspension did not have any considerable effect on the distribution of alumina particles in the samples. The hardness profiles along the height of samples were affected by both the alumina vol.% and porosity content. The presence of alumina particles increased the hardness while increased porosity reduced the hardness. Therefore, the hardness values did not show the expected gradient in same sample. The sintering resulted in decreased porosity for all the samples investigated.

Keywords: FGM, powder metallurgy, centrifugal method, polymeric suspension

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Authors: W. Handoko, F. Pahlevani, V. Sahajwalla

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Dual-phase high carbon steels (DHCS) are commonly known for their improved strength, hardness, and abrasive resistance properties due to co-presence of retained austenite and martensite at the same time. Retained austenite is a meta-stable phase at room temperature, and stability of this phase governs the response of DHCS at different conditions. This research paper studies the effect of RA stability on corrosion behaviour of high carbon steels after they have been immersed into 1.0 M NaCl solution for various times. For this purpose, two different steels with different RA stabilities have been investigated. The surface morphology of the samples before and after corrosion attack was observed by secondary electron microscopy (SEM) and atomic force microscopy (AFM), along with the weight loss and Vickers hardness analysis. Microstructural investigations proved the preferential attack to retained austenite phase during corrosion. Hence, increase in the stability of retained austenite in dual-phase steels led to decreasing the weight loss rate.

Keywords: high carbon steel, austenite stability, atomic force microscopy, corrosion

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Authors: N. Bouzouita, A. Snoussi , H. Ben Haj Koubaier, I. Essaidi, M. M. Chaabouni, S. Zgoulli, P. Thonart

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Color is one of the most important quality attributes for the food industry. Grape marc, a complex lignocellulosic material is one of the most abundant and worth less byproduct, generated after the pressing process. The development of the process of purification by micro filtration, ultra filtration, nano filtration and drying by atomization of the anthocyanins of Tunisian origin is the aim of this work. Locust bean gum is the ground endosperm of the seeds of carob fruit; owing to its remarkable water-binding properties, it is widely used to improve the texture of food and largely employed in food industry. The purification of LGB causes drastically reduced ash and proteins contents but important increase for galactomannan.

Keywords: Carob, food additives, grape pomace, locust bean gum, natural colorant, nano filtration, thickener, ultra filtration

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Authors: Ping Ren, Mao Wen, Kan Zhang, Weitao Zheng

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The improvement of comprehensive properties including hardness, toughness, wear, and corrosion resistance in the transition metal carbides/nitrides TMCN films, especially avoiding the trade-off between hardness and toughness, is strongly required to adapt to various applications. Although incorporating ductile metal DM phase into the TMCN via thermally-induced phase separation has been emerged as an effective approach to toughen TMCN-based films, the DM is just limited to some soft ductile metal (i.e. Cu, Ag, Au immiscibility with the TMCN. Moreover, hardness is highly sensitive to soft DM content and can be significantly worsened. Hence, a novel preparation method should be attempted to broaden the DM selection and assemble much more ordered nanocomposite structure for improving the comprehensive properties. Here, we provide a new strategy, by activating solid-state dewetting during layered deposition, to accomplish the self-assembly of ordered TaC@Ta core-shell-like nanocomposite film consisting of TaC nanocrystalline encapsulated with thin pseudocrystal Ta tissue. That results in the superhard (~45.1 GPa) dominated by Orowan strengthening mechanism and high toughness attributed to indenter-induced phase transformation from the pseudocrystal to body-centered cubic Ta, together with the drastically enhanced wear and corrosion resistance. Furthermore, very thin pseudocrystal Ta encapsulated layer (~1.5 nm) in the TaC@Ta core-shell-like structure helps for promoting the formation of lubricious TaOₓ Magnéli phase during sliding, thereby further dropping the coefficient of friction. Apparently, solid-state dewetting may provide a new route to construct ordered TMC(N)@TM core-shell-like nanocomposite capable of combining superhard, high toughness, low friction, superior wear with corrosion resistance.

Keywords: corrosion, nanocomposite film, solid-state dewetting, tribology

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Authors: Najeeb Niazi, Salman Nisar, Aqueel Shah

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In this study a special heat treatment process named austempering on AISI 4340 steel is carried out. Heat treatment on steel is carried out to enhance mechanical properties. In this regard, it is considered essential to undertake a study to evaluate different changes occurred in AISI 4340 steel in terms of hardness, tensile strength and impact strength at different austempering temperatures and cooling times and achieving the best combination of these improved mechanical properties for better and optimum utilization of this grade of steel. By using software Design Expert DOE is formulated with Taguchi orthogonal arrays comprising of L18 (3*3) with 03 factors and 03 responses to be calculated. Results of experiments are analyzed via Taguchi method. Signal to noise ratio of responses are carried out to determine the significant factors among the 03 factors chosen for experimental runs. Overall analysis showed that impact factor along with hardness is improved to great extent by austempering process.

Keywords: austempering temperature, AISI 4340 steel, bainite, Taguchi

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Authors: Kai-Fen Tu, Jenn-Wen Huang, Yao-Tung Lin

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Cucumber is a major economic crop in the world. The global production of cucumber in 2017 was more than 71 million tonnes. Nonetheless, downy mildew, caused by Pseudoperonospora cubensis, is a devastating and common disease on cucumber in around 80 countries and causes severe economic losses. The long-term usage of fungicide also leads to the occurrence of fungicide resistance and decreases host resistance. In this study, six types of oil (neem oil, moringa oil, soybean oil, cinnamon oil, clove oil, and camellia oil) were selected to synthesize micro/nano-sized emulsions, and the disease control efficacy of micro/nano-sized emulsions were evaluated. Moreover, oil concentrations (0.125% - 1%) and droplet size of emulsion were studied. Results showed cinnamon-type emulsion had the best efficacy among these oils. The disease control efficacy of these emulsions increased as the oil concentration increased. Both disease incidence and disease severity were measured by detached leaf and pot experiment, respectively. For the droplet size effect, results showed that the 114 nm of droplet size synthesized by 0.25% cinnamon oil emulsion had the lowest disease incidence (6.67%) and lowest disease severity (33.33%). The release of zoospore was inhibited (5.33%), and the sporangia germination was damaged. These results suggest that cinnamon oil emulsion will be a valuable and environmentally friendly alternative to control cucumber downy mildew. The economic loss caused by plant disease could also be reduced.

Keywords: downy mildew, emulsion, oil droplet size, plant protectant

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Authors: Shijie Liu, Jehnming Lin

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This study mainly discussed the mechanical properties of selective laser sintered 304L stainless steel powder specimen. According to a single layer specimen sintering, the microstructure and porosity were observed to find out the proper sintering parameters. A multi-layer sintering experiment was conducted. Based on the microstructure and the integration between layers, the suitable parameters were found out. Finally, the sintered specimens were examined by metallographical inspection, hardness test, tensile test, and surface morphology measurement. The structure of the molten powder coated with unmelted powder was found in metallographic test. The hardness of the sintered stainless steel powder is greater than the raw material. The tensile strength is less than the raw material, and it is corresponding to different scanning paths. The specimen will have different patterns of cracking. It was found that the helical scanning path specimen will have a warpage deformation at the edge of the specimen. The S-scan path specimen surface is relatively flat.

Keywords: laser sintering, sintering path, microstructure, mechanical properties

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Authors: Lia Gventsadze, Elguja Kutelia, David Gventsadze

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The purpose of the article is to show the possibility for the development of a new generation, eco-friendly (asbestos free) nano-porous friction materials on the basis of Georgian raw materials, along with the determination of technological parameters for their production, as well as the optimization of tribological properties and the investigation of structural aspects of wear peculiarities of elaborated materials using the scanning electron microscopy (SEM) and Auger electron spectroscopy (AES) methods. The study investigated the tribological properties of the polymer friction materials on the basis of the phenol-formaldehyde resin using the porous diatomite filler modified by silane with the aim to improve the thermal stability, while the composition was modified by iron phosphate, technical carbon and basalt fibre. As a result of testing the stable values of friction factor (0.3-0,45) were reached, both in dry and wet friction conditions, the friction working parameters (friction factor and wear stability) remained stable up to 500 OC temperatures, the wear stability of gray cast-iron disk increased 3-4 times, the soundless operation of materials without squeaking were achieved. Herewith it was proved that small amount of ingredients (5-6) are enough to compose the nano-porous friction materials. The study explains the mechanism of the action of nano-porous composition base brake lining materials and its tribological efficiency on the basis of the triple phase model of the tribo-pair.

Keywords: brake lining, friction coefficient, wear, nanoporous composite, phenolic resin

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Authors: Gueridi Bachir, Dadache Derradji , Rouabah Farid

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This work is focused on the preparation and characterization of poly (vinyl alcohol)/silica gel/Nano-TiO2, and the study of titanium dioxide (TiO2) nanoparticles 1% on the properties of poly (vinyl alcohol) (PVA)/silica films. Fourier transform infrared (FT-IR), water contact angle, ultraviolet-visible spectrometry (UV-VIS)) were used to characterize the hybrid films obtained. The PVA/SiO2/Nano-TiO2 films were successfully synthesized. Owing to the FT-IR Analysis, the chemical bonds have clearly shown that the PVA backbone is linked to the (SiO2-TiO2) network. UV-VIS tests indicated that the hybrid films' UV shielding properties were drastically enhanced as a result of the addition of TiO2. The water contact angle results revealed that TiO2 nanoparticles used as a doping compound possess an important influence on the hydrophilicity of PVA/SiO2 as thin films.

Keywords: sol gel method, hybrid materials, PVA/SIO2/TiO2, , spectroscopical characterization

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Authors: Muhammad Imran Din

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The aim of this study was to understand the interaction between multi-walled carbon nano tubes (MCNTs) and anticancer agents and evaluate the drug-loading ability of MCNTs. Batch adsorption experiments were carried out for adsorption of 5-Fluorouracil (5-FL) using MCNTs. The effect of various operating variables, viz., adsorbent dosage, pH, contact time and temperature for adsorption of 5-Fluorouracil (5-FL) has been studied. The Freundlich adsorption model was successfully employed to describe the adsorption process. It was found that the pseudo-second-order mechanism is predominant and the overall rate of the 5-Fluorouracil (5-FL) adsorption process appears to be controlled by the more than one-step. Thermodynamic parameters such as free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) have been calculated respectively, revealed the spontaneous, endothermic and feasible nature of adsorption process. The results showed that carbon nano tubes were able to form supra molecular complexes with 5-Fluorouracil (5-FL) by π-π stacking and possessed favorable loading properties as drug carriers.

Keywords: drug, adsorption, anticancer, 5-Fluorouracil (5-FL)

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Authors: Tarek Litim, Ouahiba Taamallah

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Burnishing is a mechanical surface treatment that combines several beneficial effects on the two steel grades studied. The application of burnishing to the ball or to the tip favors a better roughness compared to turning. In addition, it allows the consolidation of the surface layers through work hardening phenomena. The optimal effects are closely related to the treatment parameters and the active part of the device. With an improvement of 78% on the roughness, burnishing can be defined as a finishing operation in the machining range. With a 44% gain in consolidation rate, this treatment is an effective process for material consolidation. These effects are affected by several factors. The factors V, f, P, r, and i have the most significant effects on both roughness and hardness. Ball or tip burnishing leads to the consolidation of the surface layers of both grades 100C6 and 16NC6 steels by work hardening. For each steel grade and its mechanical treatment, the rational tensile curve has been drawn. Lüdwick's law is used to better plot the work hardening curve. For both grades, a material hardening law is established. For 100C6 steel, these results show a work hardening coefficient and a consolidation rate of 0.513 and 44, respectively, compared to the surface layers processed by turning. When 16NC6 steel is processed, the work hardening coefficient is about 0.29. Hardness tests characterize well the burnished depth. The layer affected by work hardening can reach up to 0.4 mm. Simulation of the tests is of great importance to provide the details at the local scale of the material. Conventional tensile curves provide a satisfactory indication of the toughness of 100C6 and 16NC6 materials. A simulation of the tensile curves revealed good agreement between the experimental and simulation results for both steels.

Keywords: 100C6 steel, 16NC6 steel, burnishing, work hardening, roughness, hardness

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Authors: Imran, Murad Ali Rahat

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One of the factors affecting crop production and nutrient availability is acidic stress. The most important element decreasing under acidic stress conditions is phosphorus deficiency, which results in stunted growth and yield because of inefficient nutrient cycling. At the Agriculture Research Institute Mingora Swat, Pakistan, tests were carried out for the first time throughout the course of two consecutive summer seasons in 2016 (year 1) and 2017 (year 2) with the goal of increasing crop productivity and nutrient availability under acidic stress. Three organic supplies (peach nano-black carbon, compost, and dry-based peach wastes), three phosphorus rates, and two advantageous microorganisms (Trichoderma and PSB) were incorporated in the experimental treatments. The findings showed that, in conditions of acid stress, peach organic sources had a significant impact on yield and yield components. The application of nano-black carbon produced the greatest thousand seed weight of 164.6 g among organic sources, however the use of phosphorus solubilizing bacteria (PSB) for seed inoculation increased the thousand seed weight of beneficial microbes when compared to Trichoderma soil application. The thousand seed weight was significantly impacted by the quantities of phosphorus. The treatment of 100 kg P ha-1 produced the highest thousand seed weight (167.3 g), which was followed by 75 kg P ha-1 (162.5 g). Compost amendments provided the highest seed yield (2,140 kg ha-1) and were comparable to the application of nano-black carbon (2,120 kg ha-1). With peach residues, the lowest seed output (1,808 kg ha-1) was observed.Compared to seed inoculation with PSB (1,913 kg ha-1), soil treatment with Trichoderma resulted in the maximum seed production (2,132 kg ha-1). Applying phosphorus to the soybean crop greatly increased its output. The highest seed yield (2,364 kg ha-1) was obtained with 100 kg P ha-1, which was comparable to 75 kg P ha-1 (2,335 kg ha-1), while the lowest seed yield (1,569 kg ha-1) was obtained with 50 kg P ha-1. The average values showed that compared to control plots (3.3 g kg-1), peach organic sources produced greatest SOC (10.0 g kg-1). Plots with treated soil had a maximum soil P of 19.7 mg kg-1, while plots under stress had a maximum soil P of 4.8 mg kg-1. While peach compost resulted in the lowest soil P levels, peach nano-black carbon yielded the highest soil P levels (21.6 mg kg-1). Comparing beneficial bacteria with PSB to Trichoderma (18.3 mg/kg-1), the former also shown an improvement in soil P (21.1 mg kg-1). Regarding P treatments, the application of 100 kg P per ha produced significantly higher soil P values (26.8 mg /kg-1), followed by 75 kg P per ha (18.3 mg /kg-1), and 50 kg P ha-1 produced the lowest soil P values (14.1 mg /kg-1). Comparing peach wastes and compost to peach nano-black carbon (13.7 g kg-1), SOC rose. In contrast to PSB (8.8 g kg-1), soil-treated Trichoderma was shown to have a greater SOC (11.1 g kg-1). Higher among the P levels.

Keywords: acidic stress, trichoderma, beneficial microbes, nano-black carbon, compost, peach residues, phosphorus, soybean

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Authors: Tarek S. Jamil, H. A. Abbas, Rabab A. Nasr, Eman S. Mansor, Rose-Noëlle Vannier

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The citrate manner (Pechini method) was utilized in elaboration of a novel Nano-sized BaFe(1-x)CuxO3 (x=0.01, 0.05 and 0.10). The prepared photocatalysts were characterized by x-ray diffraction, diffuse reflectance, TEM and the surface area. The prepared samples have a mixture of cubic perovskite structure (main) and orthorhombic phases. The effect of different loads of copper as dopant on the structural properties as well as the photocatalytic activity was demonstrated. The lattice parameter and the unit cell volume of the prepared materials are given. Doping with copper increased the photocatalytic activity of BaFeO3 several times in abstraction of hazardous atrazine that causes acute problems in drinking water treatment facilities. This may be reasoned to low band gap energy of copper doped BaFe(1-x)CuxO3 attributed to oxygen vacancies formation.

Keywords: photocatalysis, nano-sized, BaFeO3, copper doping, atrazine

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Authors: Rupali Mane

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Cadmium sulfide (Cds) thin films were chemically deposited at room temperature, from aqueous ammonia solution using CdCl₂ (Cadmium chloride) as a Cd²⁺ and CS(NH₂)₂ (Thiourea) as S² ion sources. ‘as-deposited’ films were uniform, well adherent to the glass substrate, secularly reflective and yellowish in color. The ‘as-deposited ’Cds layers grew with nano-crystalline in nature and exhibit cubic structure, with blue-shift in optical band gap. The films were annealed in air atmosphere for two hours at different temperatures and further characterized for compositional, structural, morphological and optical properties. The XRD and SEM studies clearly revealed the systematic changes in morphological and structural form of Cds films with an improvement in the crystal quality. The annealed films showed ‘red-shift’ in the optical spectra after thermal treatment. The Thiourea modified CdS film could be good to provide solar cell application.

Keywords: cadmium sulfide, thin films, nano-crystalline, XRD

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Authors: Elif Aykin Dincer, Ozlem Kilic, Busra F. Bilgic, Mustafa Erbas

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Stale breads and rusk flour are used traditionally in meatballs produced in Turkey as a structure enhancer. This study researches the possibilities of using retrograded wheat flour in the meatball production and compares the physical and sensorial characteristics of these meatballs with stale bread (traditional) and rusk (commercial) used meatballs. The cooking loss of meatballs produced with using retrograded flour was similar to that of commercial meatballs. These meatballs have an advantage with respect to cooking loss compared to traditional meatballs. Doses of retrograded flour from 5% to 20% led to a significant decrease in cooking loss, from 21.95% to 6.19%, and in the diameter of meatballs, from 18.60% to 12.74%, but to an increase in the thickness of meatballs, from 28.82% to 41.39%, respectively, compared to the control (0%). The springiness of the traditional meatballs was significantly higher than that of the other meatballs. This might have been due to the bread crumbs having a naturally springy structure. Moreover, the addition of retrograded flour in the meatballs significantly (P<0.05) affected the hardness, springiness and cohesiveness of the meatballs with respect to textural properties. In conclusion, it is considered that the use of 10% retrograded flour is ideal to improve the sensorial values of meatballs and the properties of their structure.

Keywords: cooking loss, flour, hardness, meatball, sensorial characteristics

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Authors: Amir Gerayeli, Babak Moradi

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The continuously declining oil reservoirs and reservoirs aging have created a huge demand for utilization of Enhanced Oil Recovery (EOR) methods recently. Primary and secondary oil recovery methods have various limitations and are not practical for all reservoirs. Therefore, it is necessary to use chemical methods to improve oil recovery efficiency by reducing oil and water surface tension, increasing sweeping efficiency, and reducing displacer phase viscosity. One of the well-known methods of oil recovery is Alkaline-Surfactant-Polymer (ASP) flooding that shown to have significant impact on enhancing oil recovery. As some of the biggest oil reservoirs including those of Iran’s are fractional reservoirs with substantial amount of trapped oil in their fractures, the use of Alkaline-Surfactant-Polymer (ASP) flooding method is increasingly growing, the method in which the impact of several parameters including type and concentration of the Alkaline, Surfactant, and polymer are particularly important. This study investigated the use of Nano particles to improve Enhanced Oil Recovery (EOR). The study methodology included performing several laboratory tests on drill cores extracted from Karanj Oil field Asmary Formation in Khuzestan, Iran. In the experiments performed, Sodium dodecyl benzenesulfonate (SDBS) and 1-dodecyl-3-methylimidazolium chloride ([C12mim] [Cl])) were used as surfactant, hydrolyzed polyacrylamide (HPAM) and guar gum were used as polymer, Sodium hydroxide (NaOH) as alkaline, and Silicon dioxide (SiO2) and Magnesium oxide (MgO) were used as Nano particles. The experiment findings suggest that water viscosity increased from 1 centipoise to 5 centipoise when hydrolyzed polyacrylamide (HPAM) and guar gum were used as polymer. The surface tension between oil and water was initially measured as 25.808 (mN/m). The optimum surfactant concentration was found to be 500 p, at which the oil and water tension surface was measured to be 2.90 (mN/m) when [C12mim] [Cl] was used, and 3.28 (mN/m) when SDBS was used. The Nano particles concentration ranged from 100 ppm to 1500 ppm in this study. The optimum Nano particle concentration was found to be 1000 ppm for MgO and 500 ppm for SiO2.

Keywords: alkaline-surfactant-polymer, ionic liquids, relative permeability, reduced surface tension, tertiary enhanced oil recovery, wettability change

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Authors: Ricardo Torcato, Helder Morais

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The manufacture of crystal glass parts is based on obtaining the rough geometry by blowing and/or injection, generally followed by a set of manual finishing operations using cutting and grinding tools. The forming techniques used do not allow the obtainment, with repeatability, of parts with complex shapes and the finishing operations use intensive specialized labor resulting in high cycle times and production costs. This work aims to explore the digital manufacture of crystal glass parts by investigating new subtractive techniques for the automated, flexible finishing of these parts. Finishing operations are essential to respond to customer demands in terms of crystal feel and shine. It is intended to investigate the applicability of different computerized finishing technologies, namely milling and grinding in a CNC machining center with or without ultrasonic assistance, to crystal processing. Research in the field of grinding hard and brittle materials, despite not being extensive, has increased in recent years, and scientific knowledge about the machinability of crystal glass is still very limited. However, it can be said that the unique properties of glass, such as high hardness and very low toughness, make any glass machining technology a very challenging process. This work will measure the performance improvement brought about by the use of ultrasound compared to conventional crystal grinding. This presentation is focused on the mechanical characterization and analysis of the cutting forces in CNC machining of superior crystal glass (Pb ≥ 30%). For the mechanical characterization, the Vickers hardness test provides an estimate of the material hardness (Hv) and the fracture toughness based on cracks that appear in the indentation. Mechanical impulse excitation test estimates the Young’s Modulus, shear modulus and Poisson ratio of the material. For the cutting forces, it a dynamometer was used to measure the forces in the face grinding process. The tests were made based on the Taguchi method to correlate the input parameters (feed rate, tool rotation speed and depth of cut) with the output parameters (surface roughness and cutting forces) to optimize the process (better roughness using the cutting forces that do not compromise the material structure and the tool life) using ANOVA. This study was conducted for conventional grinding and for the ultrasonic grinding process with the same cutting tools. It was possible to determine the optimum cutting parameters for minimum cutting forces and for minimum surface roughness in both grinding processes. Ultrasonic-assisted grinding provides a better surface roughness than conventional grinding.

Keywords: CNC machining, crystal glass, cutting forces, hardness

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Authors: Siti Rahmah Shamsuri, Eiichiro Matsubara, Shohei Shiomi

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The 1D nanomaterial is far surpassed the 0D nanomaterial. It does not just offer most of the benefit of the 0D nanomaterial such as the large surface area, a great number of active site and an efficient interfacial charge transfer but also can assemble into free-standing and flexible electrode due to their high aspect ratio. Thus, it is essential to develop a simple and ease synthesis of this 1D nanomaterial for the practical application. Here, nickel nanowire/cellulose hybrid has been successfully fabricated via a simple liquid-phase method with the assist of the magnetic field. A finer nickel nanowire was heterogeneously nucleated on the surface of the cellulose fiber, which demonstrated the effect of the hydroxyl group on the cellulose structure. The result of the nickel nanowire size was found to vary from 66-114 nm. A detailed discussion on the mechanism of the nickel nanowire/ cellulose hybrid formation is also shown in this paper.

Keywords: cellulose nanofiber, liquid-phase reduction, metal nanowire, nano hybrid material

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Authors: Prashant G. Metri

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A numerical model is developed to study nano liquid film flow over an unsteady stretching sheet in the presence of hydromagnetic have been investigated. Similarity transformations are used to convert unsteady boundary layer equations to a system of non-linear ordinary differential equations. The resulting non-linear ordinary differential equations are solved numerically using Runge-Kutta-Fehlberg and Newton-Raphson schemes. A relationship between film thickness β and the unsteadiness parameter S is found, the effect of unsteadiness parameter S, and the hydromagnetic parameter S, on the velocity and temperature distributions are presented. The present analysis shows that the combined effect of magnetic field and viscous dissipation has a significant influence in controlling the dynamics of the considered problem. Comparison with known results for certain particular cases is in excellent agreement.

Keywords: boundary layer flow, nanoliquid, thin film, unsteady stretching sheet

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Authors: L.L. Costa, A. M. G. Brito, S. Khan, L. Schaeffer

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Microstructure resulting from the forging process is studied as a function of variables such as temperature, deformation, austenite grain size and cooling rate. The purpose of this work is to study the thermomechanical behavior of DIN 42CrMo4 (AISI 4140) steel maintained at the temperatures of 900°, 1000°, 1100° and 1200°C for the austenization times of 22, 66 and 200 minutes each and subsequently forged. These samples were quenched in water in order to study the austenite grain and to investigate the microstructure instead of quenching the annealed samples after forging they were cooled down naturally in the air. The morphologies and properties of the materials such as hardness; prepared by these two different routes have been compared. In addition to the forging experiments, the numerical simulation using the finite element model (FEM), microhardness profiles and metallography images have been presented. Forging force vs position curves has been compared with metallographic results for each annealing condition. The microstructural phenomena resulting from the hot conformation proved that longer austenization time and higher temperature decrease the forging force in the curves. The complete recrystallization phenomenon (static, dynamic and meta dynamic) was observed at the highest temperature and longest time i.e., the samples austenized for 200 minutes at 1200ºC. However, higher hardness of the quenched samples was obtained when the temperature was 900ºC for 66 minutes. The phases observed in naturally cooled samples were exclusively ferrite and perlite, but the continuous cooling diagram indicates the presence of austenite and bainite. The morphology of the phases of naturally cooled samples has shown that the phase arrangement and the previous austenitic grain size are the reasons to high hardness in obtained samples when temperature were 900ºC and 1100ºC austenization times of 22 and 66 minutes, respectively.

Keywords: austenization time, thermomechanical effects, forging process, steel AISI 4140

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Authors: Jingjing Huang, Nengwei Li, Guanghua Wei, Jiabin You, Chao Wang, Junliang Zhang

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In this work, molecular dynamics (MD) simulation is applied to analyze the mass transport process in the cathode of proton exchange membrane fuel cell (PEMFC), of which all types of molecules situated in the cathode is considered. a reasonable and effective MD simulation process is provided, and models were built and compared using both Materials Studio and LAMMPS. The mass transport is one of the key issues in the study of proton exchange membrane fuel cells (PEMFCs). In this report, molecular dynamics (MD) simulation is applied to analyze the influence of Nafion ionomer distribution and Pt nano-particle size on mass transport process in the cathode. It is indicated by the diffusion coefficients calculation that a larger quantity of Nafion, as well as a higher equivalent weight (EW) value, will hinder the transport of oxygen. In addition, medium-sized Pt nano-particles (1.5~2nm) are more advantageous in terms of proton transport compared with other particle sizes (0.94~2.55nm) when the center-to-center distance between two Pt nano-particles is around 5 nm. Then mass transport channels are found to be formed between the hydrophobic backbone and the hydrophilic side chains of Nafion ionomer according to the radial distribution function (RDF) curves. And the morphology of these channels affected by the Pt size is believed to influence the transport of hydronium ions and, consequently the performance of PEMFC.

Keywords: cathode catalytic layer, mass transport, molecular dynamics, proton exchange membrane fuel cell

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Authors: Oluwatosin A. Ijabadeniyi, Faith Semwayo

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Preference for consumption of fresh and minimally processed fruits and vegetables continues to be on the upward trend however food-borne outbreaks related to them have also been on the increase. In this study the effect of zinc oxide nanoparticles on controlling Listeria monocytogenes ATCC 7644 in tomatoes and carrots during storage was investigated. Nutrient broth was inoculated with Listeria monocytogenes ATCC 7644 and thereafter inoculated with 0.3mg/ml nano-zinc oxide solution and 1.2mg/ml nano-zinc oxide solution and 200ppm chlorine was used as a control. Whole tomatoes and carrots were also inoculated with Listeria monocytogenes ATCC 7644 after which they were dipped into zinc oxide nanoparticle solutions and chlorine solutions. 1.2 mg/ml had a 2.40 log reduction; 0.3mg/ml nano-zinc oxide solution had a log reduction of 2.15 in the broth solution. There was however a 4.89 log and 4.46 reduction by 200 ppm chlorine in tomato and carrot respectively. Control with 0.3 mg/ml zinc oxide nanoparticles resulted in a log reduction of 5.19 in tomato and 3.66 in carrots. 1.2 mg/ml nanozinc oxide solution resulted in a 5.53 log reduction in tomato and a 4.44 log reduction in carrots. A combination of 50ppm Chlorine and 0.3 mg/ml nanozinc oxide was also used and resulted in log reductions of 5.76 and 4.84 respectively in tomatoes and carrots. Treatments were more effective in tomatoes than in carrots and the combination of 50ppm Chlorine and 0.3 mg/ml ZnO resulted in the highest log reductions in both vegetables. Statistical analysis however showed that there was no significant difference between treatments with Chlorine and nanoparticle solutions. This study therefore indicates that zinc oxide nanoparticles have the potential for use as a control agent in the fresh produce industry.

Keywords: Listeria monocytogenes, nanoparticles, tomato, carrot

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Authors: Hamza Shams, Sajid Saleem, Bilal A. Siddiqui

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This paper investigates the coefficient of friction at nano-levels of commercially available superhydrophobic/oleophobic coatings when applied over 316L SS. 316L Stainless Steel or Marine Stainless Steel has been selected for its widespread uses in structures, marine and biomedical applications. The coatings were investigated in harsh sand-storm and sea water environments. The particle size of the sand during the procedure was carefully selected to simulate sand-storm conditions. Sand speed during the procedure was carefully modulated to simulate actual wind speed during a sand-storm. Sample preparation was carried out using prescribed methodology by the coating manufacturer. The coating’s adhesion and thickness was verified before and after the experiment with the use of Scanning Electron Microscopy (SEM). The value for nano-level coefficient of friction has been determined using Lateral Force Microscopy (LFM). The analysis has been used to formulate a value of friction coefficient which in turn is associative of the amount of wear the coating can bear before the exposure of the base substrate to the harsh environment. The analysis aims to validate the coefficient of friction value as marketed by the coating manufacturers and more importantly test the coating in real-life applications to justify its use. It is expected that the coating would resist exposure to the harsh environment for a considerable amount of time. Further, it would prevent the sample from getting corroded in the process.

Keywords: 316L SS, scanning electron microscopy, lateral force microscopy, marine stainless steel, oleophobic coating, superhydrophobic coating

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Authors: Adriana Hernandez-Martinez, Edgar D. Ramon-Raygoza

Abstract:

Currently, there has been a great interest, during the last years, on graphene due to its lubricant properties on friction and antiwear processes. Likewise, fluorographene has also been gaining renown due to its excellent chemical and physical properties which have been mostly applied in the electronics industry. Nevertheless, its tribological properties haven’t been analyzed thoroughly. In this paper, fluorographene was examined as an extreme pressure additive and the nano lubricant made with a cutting fluid and fluorographene in the range of 0.01-0.5% wt, which proved to withstand 53.78% more pounds than the conventional product and 7.12% more than the nano lubricant with graphene in a range between 0.01-0.5% wt. Said extreme pressure test was carried out with a Pin and Vee Block Tribometer following an ASTM D3233A test. The fluorographene used has a low C/F ratio, which reflects a greater presence of atomic fluorine and its low oxygen percentage, supports the substitution of oxygen-containing groups by fluorine. XPS Spectra shows high atomic fluorine content of 56.12%, and SEM analysis details the formation of long and clear crystalline structures, in the fluorographene used.

Keywords: extreme pressure additive, fluorographene, nanofluids, nanolubricant

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Authors: A. Azari, S. S. K. Seyyedi

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One of the unaddressed and open challenges in the nano-networking is the characteristics of noise. The previous analysis, however, has concentrated on end-to-end communication model with no separate modelings for propagation channel and noise. By considering a separate signal propagation and noise model, the design and implementation of an optimum receiver will be much easier. In this paper, we justify consideration of a separate additive Gaussian noise model of a nano-communication system based on the molecular communication channel for which are applicable for MSK and MOSK modulation schemes. The presented noise analysis is based on the Brownian motion process, and advection molecular statistics, where the received random signal has a probability density function whose mean is equal to the mean number of the received molecules. Finally, the justification of received signal magnitude being uncorrelated with additive non-stationary white noise is provided.

Keywords: molecular, noise, diffusion, channel

Procedia PDF Downloads 277

Authors: Po-Chin Liang, Yung-Chu Chen, Chi-Feng Chiang, Yun-Ping Lin, Wen-Yuan Hsieh, Win-Li Lin

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The aim of this study was to develop super paramagnetic iron oxide (SPIO) nano-particles comprised of a magnetic Fe3O4 core and a shell of aqueous stable self-doped polyethylene glycol (PEG) with a high loading of doxorubicin (SPIO-PEG-D) for tumor theranostics. The in-vivo MRI study showed that there was a stronger T2-weighted signal enhancement for the group under a magnetic field, and hence it indicated that this group had a better accumulation of SPIO-PEG than the group without a magnetic field. In the anticancer evaluation of SPIO-PEG-D, the group with a magnetic field displayed a significantly smaller tumor size than the group without. The overall results show that SPIO-PEG-D nanoparticles have the potential for the application of MRI/monitoring chemotherapy and the therapy can be locally enhanced by applying an external magnetic field.

Keywords: super paramagnetic iron oxide nano particles, doxorubicin, chemotherapy, MRI, magnetic fields

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Authors: Pravat Ranjan Pati, Alok Satapathy

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Linz-Donawitz (LD) slag a major solid waste generated in huge quantities during steel making. It comes from slag formers such as burned lime/dolomite and from oxidizing of silica, iron etc. while refining the iron into steel in the LD furnace. Although a number of ways for its utilization have been suggested, its potential as a filler material in polymeric matrices has not yet been explored. The present work reports the possible use of this waste in glass fiber reinforced epoxy composites as a filler material. Hybrid composites consisting of bi-directional e-glass-fiber reinforced epoxy filled with different LD slag content (0, 7.5, 15, 22.5 wt%) are prepared by simple hand lay-up technique. The composites are characterized in regard to their density, porosity, micro-hardness and strength properties. X-ray diffractography is carried out in order to ascertain the various phases present in LDS. This work shows that LD slag, in spite of being a waste, possesses fairly good filler characteristics as it modifies the strength properties and improves the composite micro-hardness of the polymeric resin.

Keywords: characterization, glass-epoxy composites, LD slag, waste utilization

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Authors: Mohamed Saad Gad Elzoghby

Abstract:

Nanomaterials are widely used nowadays for the consolidation of degraded archaeological limestone. It’s one of the most predominant stones in monumental buildings and statuary works. It is exposed to different weathering processes that cause degradation and the presence of deterioration pattern as cracks, fissures, and granular disintegration. Nanomaterials have been applied to limestone consolidation. Among these nanomaterials are nanolimes, i.e., dispersions of lime nanoparticles in alcohols, and nano-silica, i.e., dispersions of silica nanoparticles in water, promising consolidating products for limestone. It was investigated and applied to overcome the disadvantages of traditional consolidation materials such as lime water, water glass, and paraliod. So, researchers investigated and tested the effectiveness of nanomaterials as consolidation materials for limestone. The present study includes an evaluation of some nanomaterials in consolidation limestone stone in comparison with traditional consolidants. These consolidation materials are nano calcium hydroxide nanolime, and nanosilica. The latter is known commercially as Nano Estel and the former Known as Nanorestore compared to traditional consolidants Wacker OH (ethyl silicate) and Paraloid B72 (a copolymer of ethyl methacrylate and methyl acrylate). The study evaluated the consolidation effectiveness of nanomaterials and traditional consolidants by using followed methods, characterization of physical properties of stone, scanning electron microscopy (SEM), X-ray diffractometry, Fourier transforms infrared spectroscopy, and mechanical properties. The study confirmed that nanomaterials were better in the distribution and encapsulation of calcite grains in limestone, and traditional materials were better in improving the physical properties of limestone. It demonstrated that good results could be achieved through mixtures of nanomaterials and traditional consolidants.

Keywords: nanomaterials, limestone, consolidation, evaluation, weathering, nanolime, nanosilica, scanning electron microscope

Procedia PDF Downloads 79