Steel–magnesium alloy laminated composites can be produced by gas-driven pressure infiltration of a molten magnesium alloy between layers of stacked steel sheets followed by directional solidification of the infiltrated magnesium alloy. A key step in the process is ensuring adequate separation and alignment of the steel sheets during the process; this is achieved by introducing small dimples in the steel sheets to hold them apart during infiltration. Advantages of the process are its speed, the defect-free composites it produces, and the fact that, unlike roll-bonded composites, the steel in the composite is in an annealed condition. The ultimate tensile strength of the as-cast laminates, of 260 MPa, obeys the rule of mixtures. The uniform tensile elongation, of around 20%, makes the infiltrated laminates nearly as ductile as the bulk steel it contains, implying that the magnesium alloy in the as-cast laminates has a substantially increased tensile ductility in comparison to the bulk state in a metallurgically equivalent condition.

In this paper, a Particle Swarm Optimization (PSO) algorithm is presented to find the optimal combination of corrosion rate parameters for a refining process in the oil industry. The experimental data in this paper are constituted by results obtained from field tests. Maintenance control is a very important aspect in order to prevent substantial damage to facilities, equipment and people. Other important factor to consider is the cost of maintenance which tends to reduce the required actions. The main parameters in corrosion control are flow, concentration of sulfur species, total acid number (TAN), temperature, and chromium content. However it is not easy to know the combined effect of different variables due to synergistic effects. Particle swarm optimization (PSO) is a population based stochastic optimization technique, inspired by social behavior of bird flocking or fish schooling. The system is initialized with a population of random solutions and searches for optima by updating generations. In PSO, the potential solutions, called particles, fly through the problem space by following the current optimum particles.

This work presents a surface study of monolithic vitreous (or glassy) carbon - MVC - obtained from vitreous carbon powder. Defective MVC pieces are crushed in a ball mill and size classified by sifting. The MVC powder is mixed with furfuryl-alcohol resin and compacted in a mould using a hydraulic press. Samples with different powder granulometries are produced in this way and carbonized in a furnace under nitrogen atmosphere. Complete carbonization of the “powder” is achieved in only one day and losses due to breakage of the pieces is less than 5%. These results compare very favorably with respect to traditional MVC production methods where full carbonization may require up to seven days and losses due to breakage can be as high as 70%. After carbonization, samples are sanded and polished. Surface roughness and microstructure are characterized by light microscopy. Porosity is quantified from micrographs using ImageJ software and nanometric height variations are measured by atomic force microscopy.

The present research work analyses the influence of microalloying elements (B, Nb, V and Ti) on the tensile strength and the strain hardening behavior of a high-manganese TWIP steel. The analysis was carried out by means of true stress-true strain curves derived from uniaxial tension tests. The work hardening exponent was determined by using the Hollomon and differential Crussard-Jaoul models. Metallographic characterization was carried out to determine the metallurgical changes associated with n values. The results indicate that the Hollomon analysis results in strain hardening exponent values up to 0.46. On the other hand, the differential Crussard-Jaoul analysis establishes a clear distinction of n value for two stages of plastic deformation which are determined by a sharp slope change in the plot of ln(dσ/dε)-lnε.

Optimum machining parameters are of great concern in manufacturing environments, where economy of machining operation plays a key role in competitiveness in the market. Many researchers have dealt with the optimization of machining parameters for milling operations. In this paper, optimization procedures based on particle swarm optimization algorithm are developed for find machining parameters in milling operation. It describes development and utilization of the methodology that determines optimum Pareto’s front analyzing feed, speed and depth for milling operation. The relationships between machining parameters and the performance measures of interest are obtained by using experimental data and a swarm intelligent neural network system. Results show that particle swarm optimization is an effective method for solving multi-objective optimization problems, and also, that an integrated system of neural networks and swarm intelligence can be used to solve complex machining optimization problems.

Understanding the morphology of catalytically active materials has been approached successfully in past decades using field electron microscopy in scanning and transmission modes. In this respect, some simulated TEM measurements for unsupported promoted molybdenum di-sulfide (MoS2/Co) provided some insights about molecular structure in those catalytic layered transition metal sulfides (LTMS). However, due to poor resolution, lack of color enhancement, and other factors, sections of those materials observed under TEM do not resolve the structure by itself; in particular about the localization of cobalt atoms for promoted MoS2 unsupported catalyst. This work concludes an epitaxial growth of MoS2 slabs over (111)-Co9S8 crystallographic plane, with a stacking degree size of 6 slabs. Results presented in here are obtained using experimental HRTEM and TEM simulations using the multi-slice method with a slice thickness of 25 Å and projected potential, where ai and bi are coefficients to be determined.

The intra-particle diffusion model (IPD), proposed by Weber and Morris has been applied to the analysis of the kinetics of adsorption on activated carbon fibers with phosphate groups in the removal of cadmium ions in aqueous media. It is evident that the removal of cadmium ion kinetic model of pseudo-second order provides a better fit than the model of pseudo-first order and the intra-particle diffusion model provides the best to the sample compared activating solution: grams fibers of 1:3.

A 1/6th gas–stirred water physical model of a 140 ton steel ladle is used to evaluate mixing in air–water and air–water–oil systems to model argon–steel and argon–steel–slag systems respectively. Thickness of the slag layer is kept constant at 0.004 m. The effect of the gas flow rate (7, 17, and 37 l/min), plug position (0, 1/3, ½, and 2/3 of the ladle radius, R), and number of plugs (1, 2, and 3) on mixing time is also analyzed in this work. Gas is injected at the bottom of the ladle under several plug configurations varying both position and number of plugs. Chemical uniformity of 95% is selected as mixing criterion. Mixing times are experimentally determined when a tracer is suddenly injected into the ladle and the model is instrumented with a pH meter to track the time evolution of the tracer concentration (NaOH 1 M solution) in a given location inside the ladle. Process conditions for best mixing in both water–gas and water-gas–slag systems are: a single plug located at 2/3 of the ladle radius with a gas flow rate of 17 l/min.

Al/SiCp composites fabricated by the non-assisted infiltration route are attractive materials for various engineering applications. However, the presence of thermal stresses can impair their mechanical properties if they are utilized directly after processing. Therefore, heat treatments are potential solutions to this problem. In this work, the effect of T6-heat-treatment on the microstructure and hardness of Al/50% SiCp composites prepared by the non-assisted infiltration route is investigated. Previous to preform preparation, the SiC powders are coated with colloidal SiO2. Infiltration tests are conducted using two experimental Al-Si-Mg alloys. The composites are sectioned in specimen sizes of 1 cm2 and prepared using standard metallographic procedures. Then they are heat treated performing a solution treatment at 350°C for 3 h and artificial aging at 170°C for 1, 3 and 5 hours. In addition, the specimens are characterized by X-ray diffraction (XRD), optical microscopy, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). They are also characterized in hardness tests, comparing the behavior for the alloy with and without the various treatments. The results show that heat treatments do not affect the matrix/reinforcement interfacial condition and that the undesirable Al4C3 phase is not developed as consequence of thermal treatments. Hardness tests show that for alloy 1 the maximum hardness value is for the solution-heat-treated samples at 350°C and 5 h aging (28.26±4.02 HC); for alloy 2 the maximum hardness is achieved with solution heat treatment at 350°C and 3 h aging (25.86±4.05 HC). For composites processed with alloy1, the maximum hardness is obtained for the solution treated sample at 350 ° C for 3 h (91.8±2.17 HC), whereas for composites processed with alloy 2 the peak hardness is obtained in solution treated samples and aged at 170°C for 1 h (95.2±0.94 HC).

The roll of lubricants in the cold-drawn process is very important to obtain a good quality on the surface of aluminum and copper wires. The viscosity of a lubricant is closely related to its ability to reduce friction. When the viscosity of a lubricant is too low, the lubricated component will have inadequate protection and will therefore be subject to excessive wear. When the viscosity of the lubricant is too high, the lubricated component will expend additional energy to complete its task. In this work, the rheology behavior of traditional lubricants for the cold drawn of Al and Cu is determined from experimental data of viscosity Vs shear rate. To evaluate the efficiency of each lubricant, the roughness surface of each wire is measured by Atomic Force Microscopy (AFM). In this way a minimum of roughness in wires corresponds to the viscosity required for each cold-drawn process. It is known that different lubricants are used for the cold drawn of Al and Cu. In this work, a new lubricant developed with the aim to be used in both process is characterized by FTIR, rheometer analysis and AFM. Results have indicated that, this new lubricant with a low viscosity that promotes a lower energy process, also decreases the roughness of Al and Cu wires compared with conventional lubricants, i.e.it has an important influence in the quality of the wires surface. This means that this new lubricant could be used during the process of both metals without making important changes, which means low operations costs and flexibility for the manufacturing plant.

A method for obtaining of amorphous aluminium ammonium phosphates is developed. The statistical program STATISTICA 9 is used for planning and evaluation of the experiments. Research is carried out according to the Box-Behnken model for the following values of independent variables (input factors): pH: 6.0 ± 2; concentration of reagents: 40 ± 10 wt%, molar ratio of NH4+:PO43- in substrates (2 ± 1:1) i.e. Al3+:NH4+:PO43- (0.66:1-3:1). On the basis of this research, process parameters are determined, in which materials with the expected physicochemical properties (chemical composition, specific surface area, oil absorption number) can be obtained.

This work studies the synthesis of styrene copolymers obtained from the reaction between isophthalic unsaturated polyester resins and styrene with the aim of improving the mechanical properties of sheet moulding compounds (SMC), specifically their flexibility and impact resistance.

The experimental work involves the experimental design; the SMC synthesis with different concentrations of 4 additives (methylmethacrylate; diethylenglycol, dioctilphthalate, and a commercial flexible resin); and the mechanical characterization including measurements of load-deflection curves; flexural strength (FS), flexural modulus (FM) and impact resistance (IR).

Adequate mechanical properties are important for both structural and functional applications of materials. There are significant differences in mechanical behaviour of different B2 ordered alloys and these are related to the properties of superlattice dislocations. Several types of dislocations can be activated, in particular <111> and <001> dislocations gliding on {110} planes. Their mobility can vary markedly from material to material and this has a strong impact on the mechanical properties. With the aim to elucidate qualitatively the differences between different alloys crystallising in the same B2 structure we analyse possible dislocation dissociations. The model employed is based on the isotropic elasticity but includes an important characteristic of stacking-fault-like defects involved in the splittings, the deviation of their displacements away from the usually assumed ½<111> APB.

The effect of mechanical activation on the crystallization of glasses of the system SiO2-Fe2O3-BaO-Al2O3 is investigated. The ceramic-glasses are synthesized from silica and iron-rich Ferro-Titanium-Zirconiferous (FTZ) sands available in the state of Coahuila, Mexico. The parent glass is subjected to mechanical activation in a high-energy attrition mill during 4 or 8h. Then, both milled and non-milled glasses are subjected to a thermal crystallization treatment at temperatures of 900 or 1000ºC during 2 or 5h. It is found that, in the case of the thermal treatment carried out at 900°C/5h, an increment in the time employed for both the mechanical activation and the crystallization treatment enhanced the crystallization of the parent glasses and produced an increase in the compressive strength of the synthesized glass-ceramics.

The density, Vickers microhardness and crystallization fraction of glass-ceramic materials synthesized from parent glasses are determined in which CaO is gradually substituted by SrO. The chemical composition (in mol.%) of the parent glasses is 54SiO2-(23-X)CaO-12MgO-5Al2O3-6CaF2-XSrO, where X is the employed CaO substitution level (X = 0, 3, 6 and 9 mol.%, with X = 0 corresponding to the reference material). In order to determine the type of crystallization occurring in the glass-ceramic samples, as well as the crystalline phases formed in them, these are characterized by both Scanning Electron Microscopy (SEM/EDS) and X-Ray Diffraction (XRD). Independently of the CaO substitution level employed, the glass-ceramics show the formation of a solid solution corresponding to diopside-type pyroxene, with chemical formula Ca(Mg,Al)(Al,Si)2O6, as a single crystalline phase. The synthesized glass-ceramic materials with the reference composition show the highest Vickers microhardness and crystallization fraction, as well as the lowest density.

Rotating bending fatigue test are carried out on the aluminum alloy 6063-T5 for corroded and non corroded specimens. Special attention is devoted to fatigue endurance reduction caused by controlled surface corrosion on corroded specimens. Corrosion attack is implemented by submersion of specimens in an acid solution for: two, four and six minutes in order to induce three degrees of surface corrosion. The corrosion agent is a solution of hydrochloric acid with a PH close to 0.8 and solution concentration of 38%. Rotating bending fatigue tests at frequency of 50 Hz, room temperature and without environmental humidity control are carried out on 4 types of specimens: without corrosion and 2, 4, and 6 minutes immersed in the solution of hydrochloric acid. Results are analyzed regarding the corrosion effect on fatigue endurance and conclusion are enlisted concerning rotating bending fatigue tests and corrosion attack on this aluminum alloy.

In the present work the influence of different modifiers, calculated to B2O3, CeO2, Sb2O3, ZnO, and ZrO2, on their distribution in TiO2 is investigated. The phase composition and phase transformation of prepared rutile-TiO2 is determined by the selective leaching method, ICP-AES, XRD and FT-IR techniques. The addition of Sb2O3 to TiO2 has no influence on the anatase–rutile phase transformation, CeO2 and ZrO2 act as inhibitors of the TiO2 phase transformation and the addition of ZnO or B2O3 to TiO2 accelerates rutile formation. It is observed that boron is located in TiO2 in the form of soluble B2O3, zinc partly reacts with titanium forming co-phase TiZn2O4 and antimony addition to TiO2 presumably causing the formation of a co-phase of Sb with Ti. Cerium forms a separate phase, CeO2, and reacts partly with titanium, probably creating co-phase, CexTi(1-x)O2 (for example Ce0.8Ti0.2O2). Zirconium addition in TiO2 forms separate ZrO2 phase and solid solution of Zr with Ti.

The objective of the present work is to evaluate the Penicillium candidum filamentous fungi biocorrosion effects on AISI 4340 steel. Small AISI 4340 steel blocks are exposed to a biocorrosion process inside glass tubes containing culture media (Sabouraud Dextrose HIMEDIA broth) inoculated with Penicillium candidum spores for 14 days, at 25ºC constant temperature. The surface microstructures are evaluated by scanning electron microscopy, atomic force microscopy, and the chemical composition by energy dispersive X-ray spectroscopy. Comparison of micrographies before and after biocorrosion shows that surface structures present morphological alterations, suggesting corrosion wear. Grain contours can no longer be visualized and oxygen content on the steel surface increases to 32% after biocorrosion. Besides, topographic parameters like root mean square roughness (Rms), arithmetic mean roughness (Ra) and mean roughness (Rz) increase 57%, 132%, and 71%, respectively, from their initial values. It is concluded that AISI 4340 steel is reasonably susceptible to corrosion.

Knowledge of the mechanical and petrographic properties of limestone rocks is an important issue to different areas of science and engineering. Sedimentary limestone rock is one of the most abundant materials in the Peninsula of Yucatán used for decorative and building construction. This work studies the petrographic, mineralogical, and physical properties of three different types of limestone slabs of the state of Yucatán.