Tlalnepantla Institute of Technology
Tlalnepantla, Mexico
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Gomez-Vargas O.A.,Tlalnepantla Institute of Technology | Keddam M.,University of Science and Technology Houari Boumediene | Ortiz-Dominguez M.,Autonomous University of the State of Hidalgo
High Temperature Materials and Processes | Year: 2017

In this present study, the AISI 1025 steel was pack-borided in the temperature range of 1,123-1,273 K for different treatment times ranging from 2 to 8 h. A diffusion model was suggested to estimate the boron diffusion coefficients in the Fe2B layers. As a result, the boron activation energy for the AISI 1025 steel was estimated as 174.36 kJ/mol. This value of energy was compared with the literature data. To extend the validity of the present model, other additional boriding conditions were considered. The boride layers formed on the AISI 1025 steel were characterized by the following experimental techniques: Scanning electron microscopy, X-ray diffraction analysis and the Daimler-Benz Rockwell-C indentation technique. Finally, the scratch and pin-on-disc tests for wear resistance were achieved using an LG Motion Ltd and a CSM tribometer, respectively, under dry sliding conditions. © by De Gruyter 2017.

Pacheco-Sanchez J.H.,Toluca Institute of Technology | Zaragoza-Rivera I.P.,Tlalnepantla Institute of Technology | Bravo-Ortega A.,Monterrey Institute of Technology
Revista Mexicana de Fisica | Year: 2017

The interaction between carbon molecules and zinc dichloride molecules (ZnCl2 - zinc salt) comes to be evident by means of small molecular systems of six-carbon (linear or rings) and zinc salt. The interaction is evident through the potential energy surface (PES) of the interacting system at the ground state, starting with a molecular geometry optimization of the energy in order to get equilibrium energy of potential energy surfaces PES. This is one way to start understanding of the porous form of an adsorbent material known as activated carbon. We recognize six-carbon fragments as amorphous activated carbon after geometry optimization with zinc dichloride, which appear in several planar and non-planar forms. An adsorbent material of pollution known as activated carbon can be obtained when carbon molecules are exposed to zinc salt (ZnCl2) molecules. Some cases of the morphology of these systems are accomplished at the density functional theory level (DFT) using GGA-PW91 for exchange and correlation with dnd basis functions.

Ortiz-Dominguez M.,Autonomous University of the State of Hidalgo | Gomez-Vargas O.A.,Tlalnepantla Institute of Technology | Keddam M.,University of Science and Technology Houari Boumediene | Arenas-Flores A.,Autonomous University of the State of Hidalgo | Garcia-Serrano J.,Autonomous University of the State of Hidalgo
Protection of Metals and Physical Chemistry of Surfaces | Year: 2017

In this work, the AISI 9840 steel was subjected to the powder-pack boriding in the temperature range of 1123–1273 K for various times ranging from 2 to 8 h. A kinetic model based on the principle of mass conservation at the growing interface was used to estimate the boron diffusion coefficients through the Fe2B layers. The pack-borided samples were experimentally characterized by different techniques such as: Scaning electron microscopy, XRD analysis, Microhardness Vickers testing. The Daimler-Benz Rockwell-C indentation technique was used to assess the adhesion quality of boride coatings on AISI 9840 steel. Finally, the scratch and pin-on-disc tests for wear resistance were respectively performed using an LG Motion Ltd and a CSM tribometer under dry sliding conditions. The boron activation energy for the AISI 9840 steel was estimated as 193.08 kJ /mol by applying the present model. To confirm and extend the validity of the diffusion model, the experimental values of Fe2B layers thicknesses obtained for other boriding conditions were compared with the predicted values. © 2017, Pleiades Publishing, Ltd.

The effect of torch weaving on the microstructure, tensile strength, impact resistance and fracturing in robotic welded joints using varing welding speeds, voltages and currents was evaluated through fractography using scanning electron microscopy, tension, impact and micro-hardness tests and optic microscopy. Results indicated that linear, sinusoidal and circular weavings favored an increase of the width of the HAZ as well as a slight increase in yield resistance accompanied by hardening in comparison with a triangular weave. The latter favored larger impact energy in the HAZ with less width, containing coarse-grained ferrite due to lower tensile strength and Vickers hardness. A circular weave generated the highest level of hardening and the lowest energy absorbed in the HAZ as a consequence of an increase in yield strength related to the fine needles of acicular ferrite. A linear weave favored the greatest width of the HAZ compared with other weld weavings due to heat accumulation along the fusion line of the welded joint. Hardening and loss of toughness were evaluated through fractographic analysis showing mixed fractures mainly composed of brittle fracturing made by transgranular cleavages with facets containing well defined river patterns. © 2017, Universidade Federal de Uberlandia. All rights reserved.

Garcia-Vazquez F.,Corporacion Mexicana de Investigacion en Materiales | Aguirre A.,Corporacion Mexicana de Investigacion en Materiales | Hernandez-Garcia H.M.,Corporacion Mexicana de Investigacion en Materiales | Santiago-Bautista L.,Corporacion Mexicana de Investigacion en Materiales | And 2 more authors.
Materials Science Forum | Year: 2013

Plasma Transferred Arc (PTA) process is increasingly used in applications where enhancement of wear, corrosion and heat resistance of metals surface is required. The shape of weld bead geometry affected by the PTA welding process parameters is an indication of the quality of the weld. PTA is a versatile method of depositing high-quality metallurgically fused deposits on relatively low cost surfaces. The overlay deposited is an alloy that is hard and more corrosion resistant than counterparts laid down by Gas Tungsten Arc Welding (GTAW) or Oxy Fuel Welding (OFW) processes. Weld deposits are characterized by very low levels of inclusions, oxides, and discontinuities. This process produces smooth deposits that significantly reduce the amount of post weld machining required. Metal-Mechanic industry continuously requires recovering tool steel components subjected to severe wear. The steel known as D2 is considered to be a high carbon, high chromium cold work tool steel. In this research, weld beads were deposited on D2 steel by using PTA process with different parameters as welding current and travel speed using base nickel filler metal. In order to evaluate the metallurgical features on the weld beads/substrate interface a microstructural characterization was performed by using Scanning Electron Microscopy (SEM) and to evaluate the mechanical properties was conducted the wear test. © (2013) Trans Tech Publications, Switzerland.

Vargas-Arista B.,Tlalnepantla Institute of Technology | Gomez-Morales M.A.,Tlalnepantla Institute of Technology | Garfias-Garcia E.,Area de Ingenieria de Materiales | Garcia-Vazquez F.,Corporacion Mexicana de Investigacion en Materiales
Advanced Materials Research | Year: 2014

Two fractured pins of impact wrench were evaluated by fractography using scanning electron microscopy. This pneumatic wrench is used to the fabrication of automotive components being characterized by its power and tightening capacity. The important part of the wrench is the pin clutch impact mechanism used to generate high torque. An original pin manufactured with AISI E52100 steel adjusted 2, 580 nuts before fracture and a substitute pin of E52100 modified steel with S adjusted 7, 095 nuts before failure. Fractographic analysis in both fracture surfaces indicated a ductile-brittle mixed fracture mode. Original pin surface exhibited a granular appearance while substitute pin surface showed fibrous and rough morphology. Precipitation of nearly rounded, elliptical and elongate second-phase particles containing Cr, C and Mn measured as intergranular and transgranular particle density was observed, promoting some brittle failure zones and ductile fracture measured as the volume fraction of grain boundaries and microvoids, respectively. A larger amount of intergranular medium precipitates was found on the original pin which favored the brittle failure among the grain boundaries compared to that of the substitute pin. The ductile fracture by larger transgranular fine particle density which acted as nucleation sites of higher volume fraction of microvoids was found in the substitute pin. © (2014) Trans Tech Publications, Switzerland.

Vargas-Arista B.,Tlalnepantla Institute of Technology | Albiter A.,Mexican Institute of Petroleum | Garcia-Vazquez F.,Corporacion Mexicana de Investigacion en Materiales | Mendoza-Camargo O.,Tlalnepantla Institute of Technology | Hallen J.M.,IPN ESIQIE
Revista de Metalurgia | Year: 2014

A characterization study was done to analyze how microstructural regions affect the mechanical properties, corrosion and fractography of the Heat Affected Zone (HAZ), weld bead and base metal for pipe naturally aged for 21 years at 30 °C. Results showed that microstructures exhibited damage and consequently decrease in properties, resulting in over-aged due to service. SEM analysis showed that base metal presented coarse ferrite grain. Tensile test indicated that microstructures showed discontinuous yield. Higher tensile strength was obtained for weld bead, which exhibited a lower impact energy in comparison to that of HAZ and base metal associated with brittle fracture by trans-granular cleavage. The degradation of properties was associated with the coarsening of nano-carbides observed through TEM images analysis, which was confirmed by SEM fractography of tensile and impact fracture surfaces. The weld bead reached the largest void density and highest susceptibility to corrosion in H2S media when compared to those of the HAZ and base metal. © 2014 CSIC.

Vargas-Arista B.,Tlalnepantla Institute of Technology | Balvantin A.,CINVESTAV | Baltazar A.,CINVESTAV | Garcia-Vazquez F.,Corporacion Mexicana de Investigacion en Materiales
Materials Science and Engineering A | Year: 2012

In this paper, artificial aging of welded joints of an API 5L X52 steel pipeline was studied using ultrasonic spectral analysis. The joints were welded using submerged arc welding process and isothermally aged at 250 °C for different time intervals. Ultrasonic measurements were carried out using a high precision water immersion ultrasonic scanner which produces C-scan maps of the tested weld samples. The results of these measurements show that ultrasonic velocity was not significantly affected by aging time; only small variations were detected associated with the degradation of strength and hardness properties. On the other hand, ultrasonic attenuation measurements were more sensitive to aging in both the weld pool and base metal. An increase in the attenuation coefficient during early aging time was linked to the precipitation of fine nanocarbides and an increase in ferrite grain size. After 200. h of aging time, the attenuation coefficient decreased monotonically, this was found to be related to the nanoparticle coarsening and ferrite grain growth after long periods of over-aging time. This phenomenon was larger in the weld pool than in the base metal due to a higher increase in carbide precipitations and their lower coarsening. These results could lead to the development of a non-destructive testing method for monitoring degradation of welded pipelines having extensive years of service under over-aging conditions. © 2012 Elsevier B.V.

Gomez-Vargas O.A.,Monterrey Institute of Technology | Solis-Romero J.,Tlalnepantla Institute of Technology | Figueroa-Lopez U.,Monterrey Institute of Technology | Ortiz-Dominguez M.,Autonomous University of the State of Hidalgo | And 2 more authors.
Materials Letters | Year: 2016

To alleviate spallation and crack difficulties exhibited by a borided metallic surface when it is subjected to a normal, heavy and sliding load under dry conditions, a boron nitride coating was produced on pure iron in two stages: boriding the iron surface at 950°C for 6 h and then nitriding the pre-borided iron at 550°C for 6 h. The powder-pack technique was used in both stages. XRD measurements confirmed that the grown layers were nitrides and duplex borides. The produced diffusion of the layers reached 240 μm in depth as measured by SEM images. The measured microhardness across the case favoured the interphase cohesion between the iron nitrides and iron borides layers. Consequently, the multicomponent coating exhibited superior wear resistance to an applied normal load under dry sliding contact conditions in comparison to borided iron. © 2016 Elsevier B.V. All rights reserved.

Vargas-Arista B.,Tlalnepantla Institute of Technology | Romero J.S.,Tlalnepantla Institute of Technology | Angeles-Chavez C.,Mexican Institute of Petroleum | Albiter A.,Mexican Institute of Petroleum | Hallen J.M.,Laboratorios Pesados Of Metalurgia
International Journal of Electrochemical Science | Year: 2011

Corrosion behavior of welded joints in API5L-X52 pipe steel aged at 250 °C at different times was investigated under electrochemical technique like tafel polarization, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies. The electrochemical results which were performed in a solution of brine containing hydrogen sulfide at 25 °C, revealed an increase of the general corrosion rate in the weld bead, the heat affected zone and the base metal as the aging time was elapsed. The corrosion rate higher was linked to the transgranular precipitation of fine nanoparticles of cementite and niobium carbide ocurred during accelerated aging process until 500 hours and their coarsening process after this time. The SEM study of the corrosion products at the three different zones showed the presence of oxide and sulphur of iron very brittle and porous on metallic surface. The highest corrosion rate was reached by the weld bead owing to the largest increase in the amount of nanocarbides, lesser coarsening and the presence of corroding products with larger brittleness and porosity. © 2011 by ESG.

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