Cálculo de blindajes para nueva instalación de tomoterapia, Braquiterapia HDR y simulador ct

En el Centro Estatal de Cancerología de Durango, como parte de un proyecto de actualización tecnológica y ampliación de los servicios de la institución, se prevé la instalación de un acelerador lineal clínico marca Accuray, modelo TomoTherapyHD (ATT); un sistema de braquiterapia de alta tasa, marca Eckert&Ziegler, modelo Multisource (EMS) y un simulador tomográfico (SCT). Este trabajo describe el proceso de obtención de los espesores de blindajes para estos equipos y los resultados de la simulación numérica de la efectividad de los mismos

Electrochemical Properties of Al2O3-Fe/Si Composites Prepared by High-Energy Mechanical Milling

open accessThe growing demand in the manufacture of advanced materials with desired and unique properties (e.g. high mechanical strength, durability, good corrosion resistance and low cost of maintenance/replacing) is one of reasons to motivate the researchers to pay special attention in Ceramics as high performance materials for industrial applications. This is because conventional materials cannot meet the engineering requirements during their service that is why the need for advanced ceramic materials to achieve these industrial requirements. In the present work a study was made on Al2O3-matrix ceramic composites reinforced with 2%wt. or 5% wt. of Fe/Si particulates that were produced using a mechanical ball milling at high-energy condition. The electrochemical behavior of these ceramics was investigated by anodic polarization and Electrochemical Impedance Spectroscopy (EIS) measurements in a solution containing 0.5N NaCl, whereas the morphology and microstructural features were examined by optical or Scanning Electron Microscopy (SEM)

Synthesis of TiB2 -Ni3 B nanocomposite coating by DC magnetron sputtering for corrosion-erosion protection

The research and development of functional coatings of new metal-ceramic materials using a new route of processing that combines Mechanical Alloying and PVD Sputtering offer great possibilities for protecting components exposed to aggressive environments where the wear and corrosion at high temperature are the leading root cause of failures.Significant contribution on corrosion-erosion resistance of Ni3B-TiB2 nanocomposite coating of 1 μm of thickness, deposited by DC magnetron Sputtering on stainless steel 304 substrates was studied. Nickel phase (γ Ni) plus Ni3B-TiB2 phases were synthesized previously by Mechanical Alloying (MA). Solid cathode (76.2 mm of diameter and 3 mm of thickness) used to grow thin films was manufactured with the alloyed powders, applying a uniaxial load of 70 MPa at room temperature and sintered at 900 °C for two hours. Microstructure and mechanical properties of the coatings were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), nanoindentation, and wear test with a ball-on-disc tribometer. Compact coating of Ni3B-TiB2with a microstructure of prismatic crystals after annealing treatment, showing a uniform coating with good adherence and low friction coefficient of 0.5, correlated with a low roughness of Ra ≈ 0.0439 ± 0.0069 μm. The average hardness of 537.4 HV(5265.0 MPa) and wear coefficient at room temperature of 2.552E-10 m2 N−1 correspond with medium-hard phases with an elastic-plastic behavior suitable for fatigue applications. Geothermal fluid modified was synthesized in the lab with NaCl/Na2SO4 to evaluate the corrosion resistance of the films in a standard three electrodes cell, characterizing a corrosion rate of 0.0008 and 0.001 mm* year−1 at 25 and 80 °C respectively during 86.4 ks(24 h) of exposition; showing a resistive coating without corrosion products and with good response to the geothermal environmen

Electrochemical Noise Analysis of Corrosion Behavior of Stainless Steel 304 Exposed in NaCl and FeCl3 solutions

The authors thanks to the Center of Research and Technological Development in Electrochemistry, S.C. (CIDETEQ) who supported this research with the scholarship conceded by the National Commission on Science and Technology (CONACYT). Also, thanks to the Autonomous University of the Mexican State (UAEM) for the research project conducted in CU UAEM Valle de Mexico (Laboratory of Electrochemical and Corrosion of industrial materials).Electrical parameters such as charge of the event (q), characteristic frequency (fn) and impedance (Zn) obtained from shot-noise theory have been proposed as indicators of the initiation of pitting corrosion, and have played an important role in the construction of corrosion patterns which are a good approximation to examine the evolution of corrosion type in metals and its alloys. Therefore, in this research paper, Electrochemical Noise (EN) signals (potential and current noise data) have been collected from AISI 304 stainless steel exposed to chloride solution to evaluate the pitting corrosion behavior. The electrochemical tests were carried out at standard condition during 24 hours of exposure in two chlorine solutions (NaCl and FeCl ). Noise data analysis was mathematical treated by wavelet transform in order to identify the low frequencies that lead the calculation of q, fn and Zn to plot the corrosion behavior and this was correlated with the Energy Distribution Plots (EDP) and metallographic images. The results of all the time series evaluated reveals a concordance in scale of EDP with the initiation and the growth of pitting.EVALUACIÓN MATEMÁTICA DE ACEROS INDUSTRIALES Y SU COMPORTAMIENTO ELECTROQUÍMICO MEDIANTE INTELIGENCIA ARTIFICIAL Folio asignado 4365/2017/CID Modalidad “D” Investigación Básica Aplicada Área de conocimiento Ingeniería y Tecnología Vigencia 01/06/2017 – 01/06/201

Opuntia ficus-indica (Nopal Extract) as Green Inhibitor for Corrosion Protection in Industrial Steels

Soluble extract from Opuntia ficus-indica (Nopal extract) has been proposed in this chapter as a green inhibitor due to its component called mucilage, which has the ability to retain water; for this reason, it has been used as metal corrosion protection in machinery pieces, tools and other metallic components that need to be stored for short periods. In this way, three industrial carbon steels (AISI 1018, 1045 and 4140) have been exposed in sulfuric acid (H2SO4) to evaluate the corrosion behavior with or without Nopal extract (NE). Some electrochemical techniques have been implemented to evaluate the corrosion inhibition efficiency (IE) such as DC linear polarization resistance (LPR) and AC electrochemical impedance spectroscopy (EIS). Results indicated a considerable superficial modification of steel in terms of dielectric constant and ion charge capacity. When the NE was added, the corrosion mechanism changed from localized to general attack, decreasing the corrosion rate in all cases. More susceptibility to fail by corrosion was observed in the 1045 carbon steel in comparison with the other two studied steels; these results were confirmed by the percentage of inhibitor’s efficiency of about 95%

Extracto acuoso natural de Morinda Citrifolia como inhibidor de corrosión del acero AISI-1045 en ambientes ácidos de HCl.

Mara Franco quisiera agradecer a la beca del CONACYT que le ha permitido realizar su trabajo de tesis y su visita a la Universidad Autónoma de Madrid, UAM. También se agradece al proyecto MAT2015-67557-C2-2-P del Ministerio de Economía y Competitividad por su financiación. En particular el Dr. Héctor Herrera Hernández agradece el apoyo económico recibido por el proyecto de investigación 3817/2014/CID (UAEM-Secretaria de Investigación y Estudios Avanzados). Por último, Dr. Héctor Herrera Hernández y el Dr. Iván García Orozco, reconocen al CONACyT por la distinción al mérito como INVESTIGADOR NACIONAL, SNI.Natural liquid-extract of Morinda Citrifolia as corrosion inhibitor for steels (AISI-1045) exposed to acidic environments of HCl. Both the organic and inorganic compounds commonly used in the industry to inhibit the corrosion process of metals and its alloys are mostly composed by highly toxic chemicals, in addition to being more expensive. In this research sugar-components derived from the Morinda Citrifolia (MC) leaves have been extracted in aqueous solution to perform a natural inhibitor capable to control de corrosion damage, which can replace the traditional inhibitors, being environmentally friendly. The experimental results indicate that this compound has shown excellent performance as corrosion inhibitor, reaching inhibition efficiency (EI), values up to 90% at inhibitor concentrations ranging 0.8 to 2 g•L−1 and immersion times of about 1 to 4 h. It has been found that the inhibition process takes place by the adsorption of the molecules on the surface of the metal (AISI 1045), by a physisorption mechanism.proyecto de investigación 3817/2014/CID (UAEM-Secretaria de Investigación y Estudios Avanzados)

Statistical Modelling of Pitting Corrosion: Extrapolation of the Maximum Pit Depth-Growth

Pitting corrosion is one of the main threats in the pressure vessels integrity and also causes the failure of buried pipelines steels that transport sour gas, crude oil or condensate hydrocarbon, for this reason, a reliability assessment of pressurized vessels and buried pipelines based on probabilistic mathematical modelling to estimate the remaining life-time due to pitting corrosion damage is extensively employed. Herein, a methodology for probabilistic mathematical modelling of the pits initiation process and its depth growth process is developed; both uncertain processes are well represented by stochastic models. In this methodology two stochastic models are applied; Poisson process is used to model pit initiation and Gamma process to model the pit depth-growth. Such methods are validated using data produced by computer modeling procedures. On the other hand, in the oil industry it is common not to inspect the entire vessels surface; instead of this only a small part of the surface is under inspection. According to this, the use of Block Maxima (BM) and Peak-Over-Threshold (POT) models “EXTREME VALUE STATISTICS” to characterize the probability distribution of maximum pit depths is also approached. The results indicate that POT model can evaluate efficiently the maximum pitting corrosion depths.Aknowledge and express their gratitude to CONACyT for the SNI distinction as research membership and the monthly stipend received

Synthesis of TiB2-Ni3B Nanocomposite Powders by Mechanical Alloying

Combination of good oxidation resistance, thermal stability, hardness and high strength are great interest properties in engineering and, that are possible to obtain with the Ni-Ti-B ternary system. Mechanical alloying (MA) is an alternative method and cheapest for the synthesis of this kind of metal-ceramic materials with respect to the traditional melt and quench process. The transformation sequence of all the mixtures reported the formation of (ɣ Ni) phase with a nodular morphology and identified the additional presence of the TiB2 phase (needle morphology), which was more evident with the increase of titanium content (M2 and M3 mixtures) after 24 h of milling. Thermal activation of the milled powders showed the nucleation and growth of the Ni3B (O boride) and TiB2 (Hex) as the main phases after heat treatment, where the TiB2 phase (thin flakes morphology) was nucleated onto Ni3B matrix. Ternary alloy by MA took place under a metastable equilibrium, offering the possibility to form glassy alloys for compositions, which are not accessible by melting or quenching techniques

Análisis aerodinámico de un vehículo aéreo no tripulado con forma de halcón para monitoreo de fugas de hidrocarburos

The oil pipeline network requires periodic monitoring to detect pipeline damages, which may cause oil leakage with severe environmental contamination. These damages can be generated by interference from third parties such as construction works, sabotage, vandalism, excavations, and illegal oil theft. To detect the oil pipeline damages, it can be used aerodynamic aerial vehicles (UAVs) with infrared cameras and image processing systems. This paper presents the aerodynamic analysis of a UAV with a hawk shape (wingspan of 2.20 m and length of 1.49 m) for potential application in the detection of oil pipeline failures. A 1:6.5 scale prototype of the UAV is fabricated using a 3D printer. The aerodynamic coefficients of UAV are determined using computational fluid dynamic (CFD) simulations and experimental testing with a subsonic wind tunnel. In addition, the lift and drag coefficients of UAVs are obtained as a function of Reynolds number and angle of attack. Also, the air velocity profile around UAV is estimated with the CFD model. The proposed UAV could decrease the inspection costs of pipeline networks in comparison with the use of helicopters or light aircraft.La red de oleoductos requiere monitoreo periódico para detectar daños que puedan causar fugas de hidrocarburos con severo daño ambiental. Estos daños pueden generarse por interferencia de terceros, tales como trabajos de construcción, sabotaje, vandalismo, excavaciones y sustracción ilegal de hidrocarburos. Para detectar daños en oleoductos pueden utilizarse vehículos aéreos no tripulados (UAVs) con cámaras infrarrojas y sistemas de procesamiento de imágenes. Este trabajo presenta el análisis aerodinámico de un UAV con forma de halcón (envergadura de 2,20 m y longitud de 1,49 m) para aplicación potencial en la detección de fallas de oleoductos. Un prototipo a escala de 1:6,5 es fabricado usando una impresora 3D. Los coeficientes aerodinámicos del UAV son determinados usando simulaciones de dinámica de fluidos computacionales (CFD) y pruebas experimentales con un túnel de viento subsónico. Además, los coeficientes de sustentación y arrastre del UAV son obtenidos como función del número de Reynolds y el ángulo de ataque. También, el perfil de velocidad del aire alrededor del UAV es estimado con el modelo CFD. El UAV propuesto podría disminuir los costos de inspección de oleoductos en comparación con el uso de helicópteros o vehículos aéreos ligeros

Microstructural Study of a Zn-Ni Alloy Prepared by Ball Milling Using Two Different Devices

Metallic zinc (Zn) has ben extensively used as protective coating of iron and steel for decades, but problems related with its high permeability has reduced its application. It was found that the corrosion resistance of zinc in form of alloys is increased by adding some transition metals. Recently, the Zn-Ni system is under research as an efficient alternative as anticorrosion coating for metals. Zn-Ni is mostly prepared by electroplating or thermal spray technologies, but there are some problems like: (i) fluctuation of Zn-Ni contents, (ii) the pollution caused by plating solutions and (iii) irregular thickness of the coating. The mechanical alloying (MA) technique can be used to fulfill the above issues because this route facilitates the synthesis of homogeneous materials from powder mixtures . Also, MA is frequently employed for the preparation of new materials based on mechanochemical reactions performed at room temperature, while avoiding the conventional ingot metallurgy [3]. This work deals with the preparation and study of a Zn-Ni alloy prepared by MA using two types of milling devices: a planetary which works manly through abrasion and impact of grinding balls and the Spex which works through the high-energy impact of balls. Zn-Ni was prepared from pure Ni and Zn powders, the equiatomic compositions were weighed and milled for 4 hours followed by sintering at 357°C during 1h