Bismuth is an element obtained as a sub-product in lead production; Mexico occupies the second position in the world in production of this element. Bismuth is used as iron, aluminum and copper alloying, in the pharmaceutical industry, in the cosmetics industry, etc. Bismuth is separated from lead by the Kroll-Betterton Process in which a Ca-Mg alloy is added to the melting lead to form the intermetallic compounds Ca3Bi2, Mg3Bi2 and Ca2MgBi2 which float to the surface of the bath. Unfortunately, there is little thermodynamical information of the compounds of the system Ca-Mg-Bi which can be used to study and optimize the Kroll-Betterton process in a theoretical way. In this work there were synthesized the compounds Ca3Bi2, Mg3Bi2 and CaMg2Bi2 using powders of pure elements (Ca, Mg and Bi) in the required amounts and melted under an inert atmosphere. After synthesis, the samples were characterized by X-Ray Diffraction to ensure the formation of the desire compounds. Later, calorimetric technique was used to determine the thermodynamical properties of the compounds. The results obtained by X-Ray Diffraction show the formation of Mg3Bi2 and Mg2CaBi2 species; however, there is no crystallographic information of the compound Ca3Bi2. The heating curves obtained by calorimetry show endothermic peaks, due to the presence of phases changes as is indicated in the Ca-Bi, Mg-Bi and Ca-Mg-Bi phases diagrams.

The synthesis of mullite from kaolin clay and two precursors of aluminum: α-Al2O3 and Al(NO3)3 was investigated. In order to study the temperature effect, the system kaolin-α-Al2O3 was calcined in air in a range of 1200 to 1500°C, for 2 h. For the system kaolin-Al(NO3)3, the combustion method was employed, using urea as fuel, and calcined in air at 1500°C for 2 h. The products were characterized by X-ray diffraction, scanning electronic microscopy (SEM), energy dispersive spectroscopy and particle size analysis in order to analyze and compare their morphology and structure. The crystallographic study revealed an incomplete reaction between the kaolin and the α-Al2O3. Nevertheless, in the system kaolin-Al(NO3)3, it was obtained mullite with high purity and trace amounts of cristobalite.

In this work was studied the partial substitution in the design of a refractory mix of the fine crystalline graphite for prefabricate nanoparticles of the seam source of graphite, improving the refractory properties of the material, getting a better resistant to the chemical attack by the slag and steel liquid metal. The raw materials and nanoparticles of crystalline graphite were characterized by X-ray diffraction (XRD), Sherrer equation, and scanning electron microscopy (SEM). The nanoparticles size determines the crystalline of the graphite used in the mixes obtained after different steps of mechanic milling. The nanoparticles of materials were added to the mixes in different proportions. The commercial raw materials used for this investigation were: commercial silicon carbide high purity (97% SiC), calcined bauxite (85% Al2O3), alpha calcined alumina, and crystalline graphite (94% C). Additionally, six different sizes of graphite nanoparticles were selected. The particle size of the initial commercial graphite was 0.044mm and the final nanoparticles obtained in this investigation by mechanic milling was 18 nm. The measurement of the particle size of the nanoparticles was made by the Scherrer equation, XRD and SEM.

Aluminum lithium hydroxide carbonate hydrate, also known as Al/Li layered double hydroxide or Al-Li hydrotalcite-like compound [Al2Li(OH)6]2CO3•nH2O, was prepared by reaction of lithium carbonate with ammonium dawsonite [NH4Al(OH)2CO3]. The reaction of ammonium dawsonite with a lithium carbonate satured solution at different temperatures and lithium carbonate concentrations was studied. The obtained solids were characterized by differential thermal analysis (DTA), thermogravimetry (TGA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and transmission electron microscopy (TEM). By this method, crystalline Li/Al LDH [Al2Li(OH)6]2CO3·3H2O can be obtained at 60 °C and 4 h reaction time.

We present experimental and theoretical Raman spectra of natural graphite mineral of Sonora, Mexico. In this work, we take the advantage of the utility of the RAMAN spectroscopy as a technique to determine the crystallinity and structure of graphite mineral. The RAMAN spectroscopy provides information that can be used to determine the degree of graphitization, which in turn can be used to know the metamorphic degree of the host rock. The resulting RAMAN spectra of graphite were divided in first and second order regions, in the first region (1100-1800cm-1) the E2g vibration mode with D6h crystal symmetry occurs at 1580cm-1 (G band) that indicates poorly organized graphite, additional bands appears in the first order region at 1350 cm-1 (D band) called the defect band, and another at 1620 cm-1 (D* band). The second-order region (2200-3400cm-1) shows several bands at ~2400 ~2700 ~2900 ~3300cm-1, all of them attributed to electron-phonon interactions or combination scattering. The density functional theory calculations were applied to determine the vibrational properties and the stacking layers of graphite.

Magnesium hydroxide (Mg(OH)2) nanoparticles were synthesized by chemical precipitation synthesis method. The influence of the nano-sized Mg(OH)2 on the structural modification was evaluated. The formation of Mg(OH)2 crystals were evaluated by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The particle size and morphology of Mg(OH)2was confirmed by high resolution transmission electron microscopy (HRTEM). The crystalline structure of nanoparticles was characterized by fast Fourier transform (FFT) and X-Ray diffraction (XRD), like analytical tools.

This work study the effect on aging thermal treatment on micro-alloyed steels API X70 pipe, microstructure and mechanical properties such a yield strength (Y), hardness (Hv) and Young´s modulus (E) are presented in this work. Thermal treatment consists of two phases: i) The solution treatment introducing samples in a electric induction furnace at 1100 °C for 30 min under argon atmosphere and water quenching, ii) aging process for five temperature in the range between 204 to 650 °C for 30 min of time exposition and water quenching, respectively. The microstructural characterization was examined by optical microscopy and matrix samples aging showed microstructures like acicular ferritic, polygonal ferritic and bainitic-ferritic, and the secondary phases were examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) obtained by SEM evidencing the presence of precipitates composed of vanadium (V), niobium (Nb) and titanium (Ti). The mechanical properties were evaluated by depth sensitive indentation test at the samples aging, the results showed increase of the (Hv) and (E)to the conditions of low temperature aging.

In this paper was study the effect of heat treatment on mechanical properties of an API X-60 steel used for storage and transportation of hydrocarbons.In the first stage evaluation are mechanical properties of steel heat treated by the technique of the three-point test according to ASTM 399-90 was carried out. In the second stage, characterization of the type of failure and microstructure through optical microscopy (OM) was determined; also heat treated samples were then mechanically tested for hardness (HRC) and nano-indentation. The presence of alloying elements by scanning electron microscopy (SEM) and the fracture surfaces generated in the steel with varying times, temperatures and cooling medium generated by different modes of solicitation (Bending), likewise with loading rates were determined. The results revealed a ductile fracture and microstructures (PF) ferrite-pearlite (DP), bainite -ferrite (BF) and martensite-retained and martensite/retained austenite (MA). Finally, this article discusses the effect of heat treatment followed by precipitation hardenable of steel API X-60 on the mechanical properties

In this work slow strain rate tests (SSRT) were used for the evaluation of API 5L X60 in contact with a simulated soil solution called NS4 in order to evaluate stress corrosion cracking (SCC) susceptibility. SSRT were carried out in NS4 solution at room temperature to simulate dilute ground water that has been found to be associated with SCC of low carbon steel pipelines. A strain rate of 1x10-6 sec-1 was used. According to the analysis of SSRT results, the X60 pipeline steel is highly resistant to SCC at the conditions studied. A combine fracture type it was observed: ductile and brittle with a transgranular appearance. Some pits close to the fracture zone were observed. The failure process and mechanism of X60 steel in NS4 solution are controlled by anodic dissolution and hydrogen embrittlement which was revealed with the internal cracks observed in the surface fracture. There is a relation between the strength of the steel and the SCC susceptibility, thus, increasing strength in the steel, the SCC susceptibility increases as a function of the pH solution used.

In this study, scrap from the automotive industry was used to produce aluminium foams under vacuum. Chips of an aluminium alloy LM26 were melted and 1wt. % of Mg was added for creating a viscous casting with uniform distribution of oxides. An ingot was obtained of this alloy after casting and solidification. Trials for foaming this alloy were performed by re-melting pieces under vacuum at different temperatures. A window in the vacuum chamber allowed observation of the foaming and collapse of the porous structures was observed during cooling. Characterization of the aluminum foams revealed different levels of expansion, porous structures and degrees of drainage. The best foams were obtained at 680 °C with a density of 0.78 g/cm3. This technique appears to be a feasible low cost route for producing Al foams based on scrap material.

In this work, thermoluminescence (TL) characteristics of roof tile ceramic samples previously exposed to beta radiation are reported for the very first time. TL measurements were carried out using powdered samples obtained by the the fine-grained method, with grain size ranged from 300 nm to 5 μm. Characteristic thermoluminescence glow curves showed a complex structure with a dosimetric maximum located at ~ 200 °C. TL response of roof tile samples increases as the radiation dose increases in the 25 Gy to 1.6 kGy range. One response showed a linear behaviour, with no evidence of saturation within the dose interval investigated. The entire TL glow curve exhibited a remarkable reusability during 10 consecutive irradiation-TL readout cycles. The total TL signal showed a very low fading and remained almost constant after 3 h of irradiation and the corresponding TL readout. TL dosimetry features of powdered roof tile place it as a promising material in retrospective dosimetry as well as in possible TL dating applications.

The breaking strength that can withstand solder is known as resistance welding, low resistance welding will cause a failure of the weld. This study optimized the effect of the main variables in a welding steel proceess on the mechanical propierties of the steel like the resistance welding. The main variables studied were electrode, machine, post induction, and dotted pressure. The factors that have the most influence in the resistance welding are the post induction, and the combination of post induction and the raw material.The statistical model used for the evaluation process was an analysis of variance (ANOVA) in a full crossing factorial design 2k with a second order of interaction.

This work estimate the growth kinetics of Fe2B coatings created on surface nodular cast iron ASTM A-536 class 80-56-06. The Fe2B coatings were formed by power packaging boriding process, considering three temperatures and exposure times different treatment. The hard coatings were evaluated through X-ray diffraction (XRD) and scanning electron microscopy (SEM). The model of diffusion employs the mass balance equation at the (Fe2B/substrate) interface to evaluate the boron diffusion coefficient in the Fe2B coating DFe2B, an expression of the parabolic growth constant, the instantaneous velocity of the Fe2B/substrate interface, and the weight gain in the boriding sample were establish as a function of the parameter ε(T) and η(T), dependents of boriding process in function of the temperature related and the time of boriding t0 (T), respectively in the Fe2B coating. Model validation was extended considering the treatment of 1273 and 1123 K for 10 h respectively, obtaining a good correlation with experimental data.

The Ba(Ti,Zr)O3 powders was synthesized for many methods because its properties as a piezoelectric, dielectric and ferroelectric material that insert it as an functional material, but there is little information in the studied of its optical properties. In this work Ba(Ti,Zr)O3films were produced by ultrasonic spray pyrolysis method for optical applications. The precursors used were an barium acetyl-acetonate, titanium acetyl-acetonate, and zirconium acetyl-acetonate powders dissolved in a N-N, dimethylformamide solution. Optical and morphological properties of the films shown a non crystalline structure and its emission spectra shown a broad and intense luminescence at 468nm which correspond to visible emission in the green region.

Silicon nanoparticles of 100 nm obtained by high-energy ball milling were characterized by X-ray diffraction (XRD) and transmission electronic microscopy (TEM). Results show dark areas due to a staking of defects. On the other hand, brighter areas exhibit a combination of small crystalline and amorphous zones. To fulfill and cover the micro-cracking and micro-pores generated during the welding process of 304 stainless steels joined by brazing, these nanoparticles were deposited directly in the fracture. The amorphous silicon drove the Transient Liquid Phase (TLP) at 1000°C for 20 min. This amorphous silicon decreases the energies of reaction between the substrate and melting filler. TLP increases the wettability and capillary forces between micro-cracking and micro-pores; due to that, the eutectic phase contained by the melting filler forms a liquid. Moreover, the weld beads were characterized by Scanning Electron Microscopy (SEM) to analyze the effect of silicon nanoparticles on the weld beads. These results showed that the interaction of the Si nanoparticles with metallic filler in the melting zone decreases the size and change the morphology of the present phases as well as the zone of isothermic growth.

Zinc oxide (ZnO) nanoparticles were produced using chemical precipitation synthesis with a molar ratio of 1:1, 1:2 and 1:3. The structure, chemical composition and morphology were investigated by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). XRD and EDS demonstrated that the all particles formed at different atomic proportion were of wurtzite crystal structure with the same chemical composition. SEM and TEM showed the formation of hexagonal particles with a molar ratio of 1:1 while the samples synthesized with a molar ratio 1:2 and 1:3 showed a circular shape. HRTEM and Fast Fourier Transform (FFT) demonstrated that the all particles were formed with a preferable [0001] growth direction.