This paper presents the results of the analytical study of the microstructural evolution of forged and rolled rings with a diameter greater than 2 meters, since the raw material, set-up forgings, ring rolling and heat treatments, including normalizing, quenching and tempering. Also, great care will be taken on the chemical micro-segregation. Four rings, were instrumented with 20 thermocouples each one in order to follow the thermal profile during heating and quenching. Cooling rates will be used to predict the microstructure developed under the different heat treatments and it will be compared at different positions inside the rings. It can be seen that the cooling curves obtained show no presence of soft phases, as shown in the microstructures in the figure shown below. With the results of microstructure obtained, which show martensitic structure to a greater extent, it meets the desirable mechanical properties, which are shown below.

Oil industry is very strategic for any country. Not only for their market share and their budgets, but also for the critical infrastructure interdependences that creates. Considering statistics and fractal geometry as a support for analysis, interpretation of data and as an aid in taking decisions, this paper deals with data obtained in 1994 and 2004 from the inspection of the onshore pipelines in Mexico. Making use of software Benoit and ITSM-2000, the time series were found to have a fractal behavior. Further analysis and contrast with a previous research base on artificial neural networks was also accomplished. As a result it was obtained a forecast for 2014, based on the sum of the time series of data.

In this work the change in the structural properties of cassava (manihot sculenta Crantz) thermoplastic starch (TPS) under controlled environment (humidity and temperature) was studied. Fourier Transform Infrared spectroscopy (FTIR) and X-ray diffraction (XRD) results showed an evident increasing in the amorphous phase of the TPS regarding the native starch. There was a relative decrease of the band at 1047 cm-1 associated to crystalline structure of starch compared to the amorphous peak at 1022 cm-1. The X-ray diffraction patterns confirmed the increment of the amorphous phase in the TPS samples. Likewise the X-ray diffraction patterns shows evidence of residual type C crystallinity and the formation of a new crystalline phase type VH due to the orientation induced in plasticization process. In first stage of conditioning the tensile yield stress drops from 7.5 drops to 0.5 MPa and the break strain increases 1000%. At the same time it seems that the crystallinity of the samples increases as was evidenced by the gradually increasing of the FTIR band at 1047 cm-1. In a second stage, the yield stress increases, the break strain drops and the crystallinity continue growing steadily. These findings suggest that coexist two phenomena simultaneously in the samples. A phenomenon of re-crystallization (retrogradation) that tends to make the material more stiff and a process of plasticization that tends to softening it. It seems that the latter mechanism predominates in the first stage, at short times, and the former in the second stage, at older times.

In this work was studied the effect of silicon content from 0.5 to 3 wt.% Si on the macrostructure of casting ingots. Fe-Si alloys with low contents of impurities were produced in electric induction furnace under inert atmosphere. Castings of 12.5 cm thick, 25 cm long and 30 cm high were obtained of each alloy poured into metallic mould. The ingots obtained were sectioned in slices of 12 cm wide, 25 cm high and 2 cm thick, the central slice of each ingot was prepared metallographically to reveal the macrostructure of the six cast alloys. The results indicate that alloys with low silicon levels (0.5 and 1.0% Si) and with small solidification intervals have relatively fine equiaxed grains, while alloys with higher silicon content and a higher solidification intervals present predominantly columnar grains. These macrostructures are not the usually structures linked to short and long freezing range. Another important result is the absence of dendritic structure usually present in cast alloys.

To evaluate the microstructures and mechanical properties in cross-roll rolled pure copper, comparing with conventionally rolled materials, this work was carried out. Pure copper (99.99 mass%) sheets with thickness of 5 mm were cold rolled to 90% thickness reduction by cross-roll rolling (CRR) and subsequently annealed at 400 °C for 30 min. Also, to analyze the grain boundary character distributions (GBCDs), electron back-scattered diffraction (EBSD) technique was employed. As a result, the cold rolled and annealed materials consisted of significantly refined grains than that of the initial material (100 μm). Especially, the CRR processed material showed more refined grain size (6.5 μm) in average than that (9.8 μm) of conventional rolling (CR). These grain refinements directly affected an increase in mechanical properties. Furthermore, the texture development in CRR processed material, in which <112> grains were densely distributed in the normal direction (ND), was more effective to enhance the yield strength.

The microstructural rejuvenation through non-conventional heat treatments (NCHT) of a conventional cast superalloy Inconel 939 was investigated. The primary and secondary main constituents of the NCHT microstructures were characterized through its morphology and composition applying conventional microscopy and analytical scanning electron microscope (SEM). The results showed a complete rejuvenation of the overage microstructure (disordered coarse cuboids of 1.2μm from γ´, continuous films of M23C6 carbides and coarse MC carbides as well as γ-γ´eutectics) into a more homogeneous microstructure; spherical ordered primary γ´ and secondary γ´ precipitates ranging between 357 to 442 nm and 30 to50 nm respectively and depending on the applied heat treatment. Also blocky type MC and discreet M23C6 carbides dispersed within the dendrite and in the interdendritic regions were observed. There was no evidence of the formation of detrimental phases with the NCHT, which can affect the long-term properties of the alloy during service.

A modified polyol synthesis has been utilized to study the different structures obtained in the bimetallic system of platinum (Pt) and palladium (Pd). Some results are shown in this work. Thermal methods under refluxing, carrying on the reaction up to 285 ºC, have been assayed to reduce metallic salts using ethylene glycol (EG) as reducer and polyvinylpyrrolidone (PVP) as protective reagent of the formed bimetallic nanoparticles. The special core-shell structure has been observed in these bimetallic nanoparticles, whose synthesis was assisted by Ag, showing polyhedral shapes. The average diameter size of the core has been estimated at 10 nm, and the diameter size of the shell in 13 nm, consequently the thickness of the shell is around 1.5 nm. Nanoparticles were structurally characterized with transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM) equipped with detector to generate high angle annular dark field (HAADF) images. This kind of structures have been studied and utilized to increase successfully the catalytic properties of monometallic nanoparticles of Pt or Pd according to other works. Here, the synthesis procedure is described; as the main results, several images are presented showing the obtained bimetallic core-shell structures and their fast Fourier transform (FFT), and also the size and the elemental analysis of the nanoparticles are reported, concluding that this synthesis method is very efficient for preparing bimetallic core shell structures.

Phonons and crystalline structures of Hg1−xCdxSe alloys (0 ≤ x ≤ 0.5) were studied by Raman spectroscopy and X-ray powder diffraction patterns at 298K. The crystalline alloys were prepared by a special combination of synthesis and the Bridgman method. Experimental data showed a face-centered cubic structure, (No. 216), for all samples, exhibiting a linear dependence for Cd molar fraction, x, for cell parameters, a, and the mass densities, ρ. Phonon frequencies were analyzed using the Romevi-Romevi model for phonons in multicomponent alloys, obtaining a fair agreement with experimental data. Furthermore, an algorithm to implement the Romevi-Romevi model is proposed.

Different synthesis methods has been employed to produce nanoparticles, however, chemical reduction method offer a effective route to obtained sizes nanoparticles controlled and morphologies very well defined. Iron nanoparticles were synthesized by chemical reduction using sodium borohydride (SB) NaBH4, Fe (III) Chloride hexahydrate (FeCl3·6H2O) as starting metallic salt (MS) and Poly-vinyl pyrrolidone (PVP) as surfactant agent. The nanoparticles have been characterized by transmission electron microscopy (TEM) and UV-Vis spectroscopy.

In this work, the synthesis of dense Pd/α–Al2O3 and Pd-Ag/α–Al2O3 ceramic composite membranes was done through the sequential electroless plating technique of Pd and Ag. The precursors are solutions of PdCl2 and AgNO3 and N2H4 salts, as reducing agent. The membranes were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive Spectroscopy (EDS). The permeation tests of H2 and N2 was carried out at 20 psi of pressure and at 25°C, resulted πH2=5.2x10-9 mol H2/m2·s·Pa and πN2=8.2x10-10 mol N2/m2·s·Pa.

Necessity of recognition of compound structures appears in different applications. Electrical tomography is one of perspective approach for investigation of material structures. A new special measurement scheme in electric tomography is proposed for the domain as a circle. This scheme opens possibility to construct electric tomography apparatus with faster computer recognition of structure of compounds materials, using General Ray algorithms. Computer simulation of this scheme is realised with MATLAB software and justified by numerical experiments on examples, related with electrical tomography.

This study consisted of the characterization of longitudinal cracking pattern observed in weld joint in the manufacture of 304L steel pipelines with thin wall thickness by GTAW process. These tubes are used in food and automotive industries. The cracks grown in the liquid-solid interdendritic zones at high temperatures. It was found that the cracks are associated with change on solidification mode and presence of the holes produced by shrinkage. The change in the solidification mode was associated with the presence of second phase particles. The results suggest that the formation of cracks is promoted by increasing current during the welding although the heat input is constant.

Silicon steels are materials used in construction of electric motors and transformers. Silicon is an effective element to improve the electrical and magnetic properties. During the solidification stage is defined the distribution of solute on the solid as segregation or coring. This paper researched the effect of the percentage of silicon on the microstructure and segregation profiles of the Fe-0.5wt%Si, Fe-1.5wt%Si and Fe-3wt%Si cast alloys. The samples were metallographically prepared by conventional techniques. The concentration of silicon in grain boundary regions was carried out by scanning electron microscopy (SEM) with EDS-WDS microanalysis, the morphological changes of the grain as a function of silicon was evaluated by optical microscopy. Experimental microsegregation patterns showed significant difference from the Scheil model and greater agreement with this model when considering convective-diffusive conditions. The microstructural study revealed discrepancies with the solidification pattern governed by the solidification interval.

Aluminum lithium hydroxide carbonate hydrate, also known as Al-Li double hydroxide or Al-Li hydrotalcite-like compound [Al2Li(OH)6]2CO3•nH2O, was prepared from basic aluminum sulfate. This compound was prepared by precipitation in homogeneous solution of an aluminum bisulfite solution. A sodium aluminate aqueous solution was prepared by dissolving basic aluminum sulfate in 1M sodium hydroxide. The Al-Li double hydroxide was obtained after addition of lithium carbonate satured solution to the sodium aluminate solution, at 60 °C. The synthesized powder was characterized by thermal analysis (TG, DTG and DTA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). By this method crystalline Li-Al hydrotalcite like compound with composition near to Al4Li2(OH)12CO3 •3H2O was obtained.

Often, mechanical properties of wood plates are accurately approximated through orthotropic characterization. However, the numerical values may show considerable variations in the case of real wood plates immersed in fluctuant environmental conditions, especially if the relative humidity of air (RH) is changing. Problems arising from the natural variations in RH have been reported on making musical instruments. In this work, the influence of changing RH on the mechanical properties of a guitar’s top plate (clamped on its contour) has been measured. Vibratory responses of the plate were experimentally obtained, through forced vibration, while data were recorded for several RH values, without any alteration in the experimental set-up devices. The six lowest natural frequencies of the structure were extracted from peaks detected in the responses. Natural frequencies depend on mass distribution and mechanical properties of the structure. For the highest sensed RH (67 %), each natural frequency of the plate decreased at least in 11 Hz compared with reference values measured at the lowest sensed RH (53 %). To determine the connection between the shift in natural frequencies and the changes in the wood elastic and shear modulus, a finite element model of the plate was performed. It was useful calculating natural frequencies through simulated modal analyses. Elastic and shear modulus were handled to match simulated results with experimental natural frequencies recorded for a RH=53% level. These elastic moduli must be decreased around 10 % to obtain a similar frequency decrease in the experimental natural frequencies obtained under a RH=67% level. The experimental results show quantitative information on an interaction scarcely researched, that is, the modification on mechanical properties of wood plates induced by RH variations. Sensed changes due this wood-air interaction are responsible of a modification in the behavior of musical instruments, as guitars and violins.

Manufacturing of high dimension steel rings impose several technological challenges. The lack of understanding of the principles and practices of quenching can result in inadequate hardness, excessive distortion or scrapping of costly machined components. This paper presents the results of an analytical study of the parameters of the quenching operation, among them the fluid dynamics of the agitation in the quenching media. Velocity components of the fluid were measured using an anemometer inside the quenching tank. Uniformity of agitation is compared with a Computational Fluid Dynamics (CFD) simulation. The CFD results revealed the impact of quench tank design, configuration and operation of impellers.

In this work the effect on the adsorption of Cr (VI) by thermally treated Hydrotalcite-like Material (HTM) synthesized by the sol-gel method with a Mg/Al = 2 was studied. The characterization of the HTM before and after Cr (VI) removal, as well as the kinetic studies were carried out. When the HTM are thermally treated at 350ºC the hydrotalcite crystalline structure remains and the textural properties improve. The Cr (VI) adsorption capacity of HTM was 125 mg of Cr (VI) / g of HTM. This capacity augments at 132 mg of Cr (VI) / g of HTM after heating HTM at 300°C. The crystallinity as well the porosity of the HTM diminished after adsorption of Cr (VI), due to the obstruction of both the pores and the interlayer space. The adsorption of Cr (VI) occurred before 4 minutes contact time. It can be concluded that HTM exhibits a high Cr (VI) adsorption capacity in a short time.

The stress corrosion cracking (SCC) of the commercial austenitic stainless steel type 304 was investigated as function of test temperature, microstructure and mechanical properties in acidic chloride solution (25 wt.%-MgCl2) using slow strain rate tests (SSRT). Susceptibility and mechanism of SCC was investigated using SSRT performed at strain rate of 1 x 10-6 in/s in a glass autoclave containing a magnesium chloride solution at 20, 50 and 80°C. The SCC assessment was carried out in function of the results of time to failure ratio (TFR), elongation ratio (ELR), ultimate tensile strength ratio (UTS-R), strain ratio(eR), yielding strength ratio (YS-R) and stress rupture ratio (SR-R). This assessment was complemented by some scanning electron microscopy (SEM) observations, in order to determine the type of fracture and its features. SSRT results indicate that 304 stainless steel was susceptible to SCC at 50 and 80°C. SCC susceptibility increases as the temperature increase. By the contrary, the mechanical properties decreases with temperature increase. SEM observations showed a ductile type of fracture, indicating that cracks appear to be originated from the pits, increasing the number of cracks as the temperature increases. Corrosion pits are one of the main potential sites for surface crack initiation. The stress concentration in the pits will be the nucleation site for cracks.

For the gate last approach of a high K metal gate scheme used in advanced CMOS technology, various materials were tested as wetting layers to allow Aluminum (Al) gap fill at gate widths of10 to 45 nanometers. In this study, Titanium (Ti) and Cobalt (Co) were investigated as a wetting layer for Al gap fill. It was discovered that Al-Ti and Al-Co alloys were formed during high temperature Al deposition. Alloys were characterized using XRD. Alloy’s impacts on line resistivity and subsequent Al Chemical Mechanical Polish (Al CMP) were also investigated. In addition, a model was established to predict the alloy type and alloy mole% with respect to feature size. The predicted Al mole% by this model correlated very well with 1) line resistivity trend and 2) morphologies. The model also predicted that due to Al lower electro-chemical potential than Ti, Co or its alloys, galvanic corrosion could take place depending on the chemical environment in the Al CMP slurry. Different slurry or cleaning chemical may reduce or increase the risk of galvanic corrosion. The knowledge gained with the help of the model provides clear directions on selection criteria for wetting layers, optimization for deposition processes and Al CMP consumable design to meet the challenges.