Journal des sciences et de l'ingénierie des matériaux

The adsorption of Bright Green (BG), a cationic dye, was studied by clay treatment experiments by modification with an aqueous solution of a cationic surfactant. Hexadecyltrimethylammonium bromide (HDTMA) and Cetylpyridinium chloride (CPC) were used for the modification of the clay. Clay modified HDTMA showed the greatest adsorption capacity compared to the other adsorbents studied.The adsorption of HDTMA on BG depended on the adsorbent dose, the pH of the solution, the contact time and the initial dye concentration studied. The adsorption data to correspond to the HDTMA experiments have been better described by the Langmuir isotherm model. The isothermal adsorption capacity of BG on HDTMA modified clay was found to be 45.5 mg/g (for an initial BG concentration of 50 mg/L), which is significantly higher than that of other adsorbents. The kinetics of adsorption of BG on clay modified by HDTMA has been described more precisely by the pseudo-second order kinetics model. The adsorbent was characterized by analysis of the Brunauer-Emmett-Teller surface (BET), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The BG adsorption mechanism on the surfactant-modified clay may comprise a hydrophobic interaction or van der Waals interaction or a combination of the two.

The Steel sector must be developed to meet up with challenges posed by auto parts replacement by developing auto parts production industries such as Inner and outer panels of automotive bodies, wheel housings and peripheral components, fuel tanks automotive exhaust systems, automatic fuel tanks and radiators, Steel cord for reinforcement radials tyres. Steel sector is the backbone of any economic or industrial development of any nation. The industrial revolution of the Government should aim at boosting the steel industry .To is able to produce car components, the establishment of small plants must be encouraged .The raw materials to produce car parts must come from our indigenous steel industry. In the situation of the Country where spare parts and components are not readily available therefore local production and local content must be encouraged. The research paper therefore carried out an Investment analysis to analysis the establishment of a plant for the manufacturing of Spheroidal Graphite iron for the manufacturing of spare parts, components for automobile industry. The analyzed investment proved that the amount to be invested in this plant could be recouped within the stipulated period of three years. Time value of money was considered throughout the implementation of the project. The describe investment analysis present a unique way in handling the establishment of plants of this nature. The work further looked into some areas like market potential of Spheroidal Graphite Iron, its characteristics and its vital role in engineering applications, implementation schedule, technical aspects that include all the necessary details for project execution, quality control and standard, pollution and protection within the plant, the production capacity of the plant were highlighted this shows that the plant can produce about 450 metric tonnes of finished castings in a year. The financial aspects and analysis were discussed in details, revealing the amount that could be involved in floating the plant for meeting the needs and demands that may arise from automobile industry. The overall aim of the project was achieved, this indicated that within a year of the establishment of the plant, a lot of revenue could be generated as shown from the rate of return on investment and the form break – even point. Some recommendations were given to encourage the establishment for such plants in any part of the country, which will continue to meet the demand of our local industries.

In this paper, an empirical model is applied to predict the hardness, yield strength, and tensile strength of rapid solidified ribbons. The discovered empirical equation is obtained depends upon the experimental results of rapid solidification process for 5083 Al-alloys. The empirical equations predict values and describe the behavior of ribbon with consideration of ribbon thickness, grain size, hardness, yield strength, and tensile strength. The experimental work involves difference operation conditions and the results indicate that orifice diameter, nozzle roll wheel gap, and melting temperature have direct impact on the quality of alloy. Additionally, the results showed that there is a good agreement between experimental and predicted values where the correlation coefficient is 0.99. The experimental show that there is a possibility to produce very thin ribbons with thickness in micrometer by reducing the distance between nozzle and roll wheel, and reduce the orifice diameter of casting. The hardness, and yield strength increased due to increasing the number of small grain size in the ribbons structure and rapidly heat transfer of the small ribbons thickness. Moreover, the optimal melting temperature of this alloy is 925ºC which produces high ribbon hardness compared with other melting temperature that used in this research.

Carbon/graphite materials are widely applied to the areas of seal and friction materials. These applications exploit the exceptional properties of carbon/graphite, such as its excellent mechanical behavior at high temperature and low reactivity. However, Owing to high open porosity, and low strength conventional carbon/graphite materials prepared using pulverized coke as filler and pitch as binder fall across enormous challenge. Therefore, it is necessary to reduce the open porosity and increase in the strength along with thermal conductivity. Using natural graphite as filler instead of coke to prepare carbon blocks can avoid high-temperature graphitization and repeated dipping owing to the high degree of graphitization and high thermal stability of natural graphite; thus it can simplify the working process, save energy and reduce cost. Carbonaceous mesophase has inherent properties, such as a high softening point, high fluidity, high carbon yield, and graphitizability, which make it suitable for the fabrication of polygranular carbon materials. Furthermore, it can be used as a binder. The sintering was performed in a static furnace with argon atmosphere and compared with the same compound sintered in passage furnace with hydrogen and nitrogen atmosphere. The analysis of the properties of the tested material was performed with the aid of metallography using a scanning electron microscope, which verified the particle size distribution, chemical elements and pores present. However, for the graphite powder and zinc stearate, present in smaller percentages were disregarded its influence on the physical properties of the compound generated. Compressibility and compaction are parameters that indicate and describe the behavior of metal powders as they are compressed. The ability of a powder densification is related to compressibility. Already compaction is defined as the stability of the structure of the pressed compacted to a certain working pressure. Therefore, the natural graphite as filler and mesophase pitch as binder can be able to produce high density graphite blocks. The main aim of this work is to produce isotropic graphite material and evaluation of its properties such as high density, high thermal conductivity, high electrical resistivity, low coefficient of thermal expansion, and high compressive strength from natural graphite powder mesophase pitch.

The OPLS-AA force field is well established in determining the bulk properties of molecules from molecular parameterizations. However, the comparison of such derived properties from high performance computing research has not extended to determine their applicability or breakdown in polyalkane, polyether and polysilicone materials, specifically in the context of surface activity. This letter highlights the differences in these structures attractive and repulsive forces while detailing the distances between charge centers. This paper describes the types of interactions within the OPLS-AA force field that explain polyether and polysilicone material solvophilicity, with particular focus on mixed solvent systems. It details how the solvophilicity varies with the relative strength of interactions for these materials at various alcohol contents.

After performing computations in molecular dynamics in high performance research systems, many solvable but yet unsolved problems have been determined. These include (i) a list of molecules which are of commercial and scholarly interest that can be parameterized with the available OPLS-AA literature, (ii) a list of metals in certain environments which have yet to be parameterized and would provide insight into their behavior in commercial processes, (iii) an empirical approach to searching for the impact of molecular parameterizations on observable properties which is useful in searching for new materials, and (iv) understanding molecular reactivity in computational molecular dynamics.

A formate-based fluid has been successfully used in many high pressure High temperature (HPHT) well operations since they were introduced in field practice. The laboratory research was carried out to determine composition of formate-base drilling fluid. It was formulated using sodium and potassium formate salts, Carboxymethyl Cellulose (CMC), Polyanionic Cellulose (PAC) and other types of polymers. In this research, the compatibility of different polymers with fluids, including potassium/sodium formate salts is being studied. Having said this, however, polymers, when taken to high temperatures, lose their properties. Therefore, this experimental procedure has been done at a temperature of 250°F over a period of 16 h. For doing these tests, six types of potassium/sodium formate fluids were made by different polymers. All samples formulation regarding their type and amount of water used in preparing fluids and the volume of salts used are simultaneously kept constant. On the contrary, the only differences were the types of polymers used in the different formulations. Formulation of formate-base fluids gives the best rheological properties in terms of AV/PV, YP and shale recovery than other fluids.

This manuscript details the method to determine the surface excess from readily derivable ensemble properties, namely the pressure tensor, via computational molecular dynamics. It will then expand upon the theoretical and practical uses of quantities in Gibbs-Duhem like relationships for the surface excess and molecular concentration at the interface. Furthermore, it details several limitations of computational molecular dynamics, mainly to determine force field parameters natively and also to determine criteria for switching the bond order at certain temperatures. The goal in predicting surface presence is in inter-relating the relative surface excess free energies of each species with respect to the total system relative to the free energy of hydration of that system.

This communication is centered on the optimization of a photovoltaic mill system performance operating on the sun race. According to the character of the alimented charge which is a DC motor that is running a cereal mill and the meteorological conditions (temperature and light), we can find a big difference between the potential maximal power and the other on which is really transferred to the charge. In order to ameliorate the global output of the system, we use an adapted circuit composed of a boost converter remoted by Pulse Width Modulation (PWM) with a MPPT command (Maximum Power Point Tracking). With the Perturb and Observe ((P&O) algorithm, the MPPT control measure the current and the pressure of the photovoltaic generator field to calculate the power released by this one. According to the result obtained, the MPPT control will adjust the cyclical report of the converter to bring the system to the optimal functioning point. The modelisation then simulation of the system (PV generator, boost converter, Pulse Width Modulation which the MPPT algorithm as for as the direct current charge) are after done with the Matlab/ Simulink software.

This work addresses the challenging fibre-matrix compatibilization and interface adhesion improvement of poly(etheretherketone) (PEEK) composites reinforced with pitch-based carbon fibre. An innovative and environmentally friendly method, inspired both by supramolecular “layer-by-layer” (LBL) assembly and by the composition of adhesive proteins in mussels was designed to modify the carbon fibre surface and improve the composites transverse properties by supramolecular interactions. The results proved that few sensitive carbon surfaces can be selectively modified by stable polyelectrolyte complexes and catechol amine polymer partners dispersed in water in such a way that a sizing treatment can be applied by techniques as simple as immersion or spraying procedure. It was shown that the combination of these solutions self-organized to form thin deposits containing compatibilization and/or crystallization promoter partners, thought transcrystallinity, onto carbon surface. This approach is an innovative and environmentally-friendly method which improves fibre-matrix interface quality in terms of compatibilization, adhesion and mechanical properties.

In the present paper, an investigation was carried out to evaluate the micro scale elastic behaviour of composites. The novelty of this work is to compare three different simulation methods for the composite Carbon/PPS by suggesting a 2D programing simulation approach that would reduce the calculation time of the elastic behaviour of the yarn of woven composite material. To conduct the work an experimental analysis was planned to identify the micro geometric parameters of the composite and to collect all needed dimensions for building the numerical models. The simulation procedures are carried out through three different micro-scale methods and by applying two different finite element approaches: 3D periodic approach, 3D random approach and 2D random approach, the results show that the Young modulus presents a differentiation reach 12% and the Shear Modules G13 and G12 is roughly 11% and 29.39% for G23. The micro mechanical results are discussed according to the recent literature investigations. The numerical results from the proposed approaches are discussed, which show good agreement with reality of the material when using the random 3D approach and very good gain of time of simulation when using the 2D programing simulation approach. This approach reduces the calculation time about 50% compared with other methods.

The use of polymer matrix composites (PMCs) in the gas flow path of advanced turbine engines offers significant benefits for aircraft engine performance but their useful lifetime is limited by their poor environmental resistance. Flame sprayed NiCr graded coatings are being investigated as a method to address this technology gap by providing high temperature and environmental protection to polymer matrix composites. In this research coating was spread with two configuration, coating with bound coat and coating without bound coat. In general the coating with bound coat and coating without bound coat showed increase in micro hardness and adhesion with increase curing temperature; this is due to the microstructural changes the physical splat structure of the coating also changes with heat treatment. All coating failed at the interface between the composites and the coating, failure occurs along the weakest plane within the system, some of the coating systems that have presented fracture at the bond coat/top coat interface. The surface topography of NiCr films was further examined by using AFM atomic force microscopy as a function of curing temperature at 100,200 and 300°C for 1 h each, it can be clearly seen that the island structure was observed and the Rmax increase, the surface became rougher with increasing curing temperature. The surface morphology and microstructure of the coating were examined using SEM.

Chemical synthesis results in the most convenient route to produce ceramics nanoparticles. The methodology used consists in the formation of a sol from organometallic precursors. Two different fuels, ovalbumin and urea, along with aluminum formate were used to prepare nano alpha-alumina powder. Different fuel to oxidizer ratios and different percentage combination of two fuels were used to prepare six samples. In all samples, nanoscale particle size was obtained. The addition of urea and ovalbumin promotes amorphous character below 800°C. With the fuel approach, crystallinity can be enhanced easily, by calcination of powder product at low temperature around 1050°C. The methodology has capability to produce nanophase alumina powder with wide range of particles size 40-80 nm. Therefore the use of this precursor simplifies the process and provides another alternative process for economical synthesis of crystalline alumina.

The objective of this study is to understand the loop formation phenomenon of yarn by considering their nonlinear bending behaviour and the effect of loop shape factor on properties of terry fabric. The yarn is modelled as a continuum thin solid beam, and the governing buckling equation is derived using Timoshenko’s elastic theory and the Bernoulli-Euler theorem. Since the formation of loop is effected by large deformation caused by the weight of yarn too, geometric non-linearity is also considered and Runge Kutta method of numerical technique is used to solve the governing equation. Further, finite element modelling technique is also used to see the accuracy of the prediction which is further verified by the actual experimental results. The results of the research prove that the finer yarn produce loops which are having more circularity i.e., higher loop shape factor, as compared to the loops produced from coarse yarn. It is also being proved that the increasing the loop length increases circularity of the loop i.e., higher loop shape factor.

In this research work, an attempt has been made to synthesize nano-structured gold thin films over Silicon dioxide (SiO2) coated on Silicon(Si) Substrate using three deposition techniques namely DC Sputtering, Pulsed DC Sputtering, and Pulsed Laser Deposition(PLD). Optical measurements using spectroscopic ellipsometry showed that the dielectric constants of the films differed between films synthesized by different synthesis routes. This was expected because different synthesis routes yielded different microstructure. The difference in microstructures results in differences in electronic structure and therefore resulting in the differences on the optical response.

Iron ores are used in blast furnace for the production of pig iron; AGBAJA Iron ore has an estimated reserve of over I billion metric tonnes. Unfortunately, this large reserve cannot be utilized for the production of pig iron due to its high sulphur contents. This work studied the reduction of sulphur content of AGBAJA iron ore. Acid leaching methods were used to reduce sulphur contents of the ore sulphuric acid of different concentrations were used at various leaching times, acid concentrations and particle sizes. Atomic Absorption Spectrophotometer, X-ray fluorescence spectrophotometer, Digital muffle furnace and Absorbance-concentration technique were used for experimentation and chemical analysis. The reduction of the sulphur content of AGBAJA Iron Ore using Acid leaching process experiments were carried out at the National Metallurgical Development Centre (NMDC), Jos in Plateau State of Nigeria. Sulphur is one of the main harmful elements in ferrous metallurgy and it affects the quality of iron and steel produced. At present, Nigeria has some large iron ore deposits including AGBAJA which bear tremendous iron ore with high sulphur content of 0.12%. Central composite design technique was applied to obtain optimum conditions of the processes. Surface response plots were also obtained. The percentage degrees of reduction of sulphur content of AGBAJA Iron ore were found to increase with increase in acid concentration and leaching time and a decrease in particle size for the three acids. The experimental results for percentage removal of sulphur are 87.77% the optimum % removal of sulphur is 87.73%. The result of this work has shown that AGBAJA Iron Ore if properly processed can be used in our metallurgical plants and also can be exported since sulphur contents of the ore have been reduced drastically.

The aim of the present review is to present some phenomenological observations on compression fatigue crack propagation of nacre samples. The first part of the paper reviews the characteristics of hierarchical structure and the mechanical properties of nacre, which characterize its specific properties. We have investigated the main chemical constituents of nacre and determined their mineral elements. Electron microscopy studies revealed that nacre is composed of a single-crystal aragonite. In the second part of the paper samples of nacre have been tested in compression-compression fatigue under cyclic loading and a Paris curve have been constructed at a fatigue ratio of about 10, subjected to a 30 Hz sinusoidal compressive load. It has been demonstrated that two driving forces ΔK and Kmax mainly govern the overall fatigue crack growth of nacre. Nacre shows considerable ability to stop cracking. By means of axial compression tests, we identified a single elastic and inelastic property. Measurements based on experiments were first done. Mean values of compressive strength and modulus of elasticity were obtained for several samples. A three-point bending test was performed on polished nacre samples according to the international standards for Young’s modulus, bending strength. An attempt is made to explain qualitatively the mechanical behavior of nacre in terms of its submicroscopic structure. It is concluded that the precise geometric arrangement of the plates is highly important. The results obtained provide a director for the design of orthopedic implants.

The present study report the synthesis of alumina fibre by annealing method using coir fibre. In this study chemical treatment of coir fibre has been done using a nitro compounds at higher temperature. The composite formed after the chemical treatment has been characterized by Xrd, SEM and FTIR technique. Successful synthesis of alumina fibre has been confirmed after the chemical treatment of coir fibre.