Luis López-Léon - Academia.edu (original) (raw)
Papers by Luis López-Léon
Pädi Boletín Científico de Ciencias Básicas e Ingenierías del ICBI
Estimadas y estimados lectores El desarrollo humano sostenible es un concepto que implica mejorar... more Estimadas y estimados lectores El desarrollo humano sostenible es un concepto que implica mejorar la calidad de vida de las personas y satisfacer sus necesidades presentes sin comprometer la capacidad de las generaciones futuras para satisfacer sus propias necesidades. Aplicar técnicas de ingeniería industrial, arquitectura, urbanismo e ingeniería civil en el contexto del desarrollo humano sostenible implica diseñar, planificar y ejecutar proyectos y procesos de manera que promuevan la sostenibilidad ambiental, social y económica. Las disciplinas de la ingeniería industrial, arquitectura e ingeniería civil desempeñan un papel crucial en la planificación y ejecución de proyectos que promuevan la sostenibilidad en términos ambientales, sociales y económicos. En el entorno del desarrollo sustentable el Área Académica de Ingeniería y Arquitectura (AAIyA) manifiesta mediante la Edición Vol. 11 No. Especial 3 (2023), los 22 trabajos desarrollados y aceptados conforme a las siguientes temá...
Pädi Boletín Científico de Ciencias Básicas e Ingenierías del ICBI
La insostenibilidad del crecimiento urbano demanda gran cantidad de recursos naturales. Una opció... more La insostenibilidad del crecimiento urbano demanda gran cantidad de recursos naturales. Una opción para mitigar este gran consumo es el reúso de residuos de la construcción y demolición en sustitución del cemento y agregados. Se diseñó y construyó un muro verde con concreto ecológico; éste consistió en 10% de concreto triturado en sustitución del cemento y 30% de vidrio en lugar de arena. El relleno de sus macetas contiene suelo vegetal, concreto triturado que sustituyó a las gravas y tabique rojo triturado en lugar de arena. Se determinó que el muro verde ecológico es 7.37% más económico que uno fabricado con materiales naturales. El relleno de las macetas representó 72.08% de ahorro, mientras que el concreto ecológico sólo un 6.1%, dado que el cemento es el material más costoso y se sustituyó únicamente un 10% de la cantidad necesaria. Se concluye que los residuos de la construcción y demolición son una opción económicamente viable para reducir el consumo de recursos naturales com...
Metals
Aluminum and its alloys find widespread applications across diverse industries such as the automo... more Aluminum and its alloys find widespread applications across diverse industries such as the automotive, construction, and aeronautics industries. When these alloys come into contact with ambient air, an Al2O3 thin oxide layer is naturally formed, typically measuring 2 to 4 nm and exhibiting remarkable hardness and protective qualities, rendering the alloys corrosion-resistant in specific atmospheric and chemical environments. This study aimed to characterize the electrochemical behaviors of anodized AA2024 and AA7075 alloys within a complex three-component electrolyte composed of tartaric–phosphoric–sulfuric acid (TPSA) solutions. The anodized specimens were subsequently exposed to 3.5 wt.% NaCl solution at room temperature, and their electrochemical performances were meticulously evaluated using an electrochemical noise (EN) analysis in accordance with ASTM G-199, respectively. In the EN, three methods of data analysis were used: the time domain analysis (chaos analysis: application...
International Journal of Electrochemical Science, Nov 1, 2019
This work presents an electrochemical evaluation of a proposed mucilage-based corrosion-resistant... more This work presents an electrochemical evaluation of a proposed mucilage-based corrosion-resistant hybrid coating. The process started with the extraction of mucilage from Opuntia streptacantha and the formulation of 4 coatings containing 0.2, 0.3, 0.4 and 0.5 g of mucilage. The process continued with the coating of rebars through immersion. The rebars were allowed to dry, and then the coating thickness was measured by ultrasound. Optical micrographs were used to characterize the hybrid coating conditions after their evaluation. Working specimens were evaluated using electrochemical impedance spectroscopy and potentiodynamic polarization curves after 24 hours of immersion in a 3.5 wt.% NaCl solution. The mucilage-based hybrid coating reveals enhanced corrosion protection compared to steel without a coating. The obtained results show that the hybrid coating has favorable properties as a barrier due to its ability to obstruct the diffusion of aggressive species by trapping them in the coating structure, which avoids their adsorption on the metallic surface. This effect is due to the homogeneity of the mucilage in the coating, which acts as a corrosion inhibitor due to its semipermeable behavior, where only water molecules flow through its pores, showing promising results as a corrosion-resistant coating.
Sustainability, Dec 7, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Metals
Titanium alloys present superior electrochemical properties due to the generation of the TiO2 pas... more Titanium alloys present superior electrochemical properties due to the generation of the TiO2 passive layer. The ability to generate an oxide passive layer depends on the anodized alloy. This work mainly studies the corrosion resistance of the alloys Ti-6Al-2Sn-4Zr-2Mo and Ti-6Al-4V anodized in NaOH and KOH at 1 M and 0.025 A/cm2 of current density. The electrochemical techniques were performed in a conventional three-electrode cell exposed to electrolytes of NaCl and H2SO4. Based on ASTM-G61 and G199, cyclic potentiodynamic polarization (CPP) and electrochemical noise (EN) techniques were used. The results indicated that Ti-6Al-2Sn-4Zr-2Mo anodized on NaOH presented a higher passivity range than anodized on KOH, relating to the high reactivity of Na+ ions. The former anodized alloy also demonstrated a higher passive layer rupture potential. In EN, the results showed that Ti-6Al-4V anodized in KOH presented a trend toward a localized process due to the heterogeneity of anodized poro...
Tópicos de Investigación en Ciencias de la Tierra y Materiales
En este trabajo de investigación se estudia una alternativa de reutilización de materiales de des... more En este trabajo de investigación se estudia una alternativa de reutilización de materiales de desecho industrial en concreto reforzado buscando determinar parámetros experimentales de resistencia a la corrosión de los distintos sistemas de concreto, en comparación a un concreto reforzado convencional. El uso de la técnica de espectroscopia de impedancia electroquímica muestra que la interacción del jal como cementante no modifica el proceso de corrosión, pues se observa que el uso de residuo minero hasta un 10% no favorece la llegada de los agentes corrosivos a la superficie de la varilla de refuerzo en el concreto comparado a un sistema convencional. Los valores de Rp son muy similares para los distintos sistemas. La interacción de cloruros con el metal se ve aumentada al usar 15% en la dosificación de jal como cementante, modificando considerablemente la velocidad de corrosión del sistema. El concreto elaborado con jal como cementante tiene un comportamiento electroquímico y mecán...
Materials
In the aeronautical industry, Al-Cu alloys are used as a structural material in the manufacturing... more In the aeronautical industry, Al-Cu alloys are used as a structural material in the manufacturing of commercial aircraft due to their high mechanical properties and low density. One of the main issues with these Al-Cu alloy systems is their low corrosion resistance in aggressive substances; as a result, Al-Cu alloys are electrochemically treated by anodizing processes to increase their corrosion resistance. Hard anodizing realized on AA2024 was performed in citric and sulfuric acid solutions for 60 min with constant stirring using current densities 3 and 4.5 A/dm2. After anodizing, a 60 min sealing procedure in water at 95 °C was performed. Scanning electron microscopy (SEM) and Vickers microhardness (HV) measurements were used to characterize the microstructure and mechanical properties of the hard anodizing material. Electrochemical corrosion was carried out using cyclic potentiodynamic polarization curves (CPP) and electrochemical impedance spectroscopy (EIS) in a 3.5 wt. % NaCl ...
Energy Exploration & Exploitation
This research targets to present a case study on the annual comparative assessment of photovoltai... more This research targets to present a case study on the annual comparative assessment of photovoltaic thermal collectors (PV/T) by using water and Ag/water nanofluid for five different cities in Pakistan. The assessment is conducted at monthly, daily, and hourly resolutions. PV/T collector is imitated through a set of energy balance based physical models which are solved numerically for two working fluids (i.e. water and Ag/water nanofluid) in a yearly simulation format (with hourly, daily, and monthly predictions) for five major cities of Pakistan (Taxila, Peshawar, Multan, Lahore, and Karachi). Detailed comparative assessment is carried out based on the performance indicators such as electrical efficiency, thermal efficiency, heat gain, and net electricity power generation. In the results section, hourly, daily, and monthly patterns of performance indicators using water and Ag/water nanofluid are reported, followed by a comparative study between the different cities having different ...
Pädi Boletín Científico de Ciencias Básicas e Ingenierías del ICBI
Una tendencia en el área de la edificación es elaborar elementos constructivos con material de de... more Una tendencia en el área de la edificación es elaborar elementos constructivos con material de desecho diversos, mostrando buenos resultados en pruebas físicas experimentales en comparación con prototipos convencionales. En este trabajo se elaboraron tabicones de concreto modificados sustituyendo un porcentaje de material pétreo por polímero Noryl (poli óxido de fenileno). Un punto importante para considerar en el uso de este tipo de elementos es la prueba de carbonatación, la cual sirve como instrumento para simular de forma acelerada el daño por carbonatación en los especímenes sometidos a un ambiente agresivo. El objetivo de esta investigación fue analizar los perfiles de carbonatación de los distintos especímenes con la prueba de fenolftaleína y medición de pH. Los resultados muestran una disminución en el proceso de carbonatación de los especímenes modificados en comparación con los tabicones comerciales.
Pädi Boletín Científico de Ciencias Básicas e Ingenierías del ICBI
La resistencia a la compresión de mezclas de concreto se consigue al diseñar sistemas que cumplan... more La resistencia a la compresión de mezclas de concreto se consigue al diseñar sistemas que cumplan con propiedades mecánicas y de durabilidad establecidas por normas nacionales e internacionales. En este trabajo se propone un elemento actuador de carga personalizado en la generatriz, tanto en la parte superior e inferior de la celda para tener mejor distribución de carga en el espécimen y ejercer un apoyo uniforme en la sección de contacto para el ensayo de tracción indirecta. En este proyecto se diseñó y manufacturó un dispositivo que podrá servir como instrumentación de la prensa marca Controls modC-43C04 para dar servicio a probetas, en las cuales el concreto es sometido a esfuerzos de tensión con mayor intensidad, donde se espera que el acero de refuerzo sea quien actúe al absorber estos esfuerzos. A través de las pruebas de mecánicas se estableció que la celda cumple con un diseño funcional y con las necesidades de la prensa para la que fue adaptada.
Metals, 2021
Hard-anodized is a widely used method in the aeronautical sector to improve aluminum alloys abras... more Hard-anodized is a widely used method in the aeronautical sector to improve aluminum alloys abrasion and corrosion resistance. Aim of this work was to characterize the mechanical properties and resistance hard-anodized aluminum 6061 in citric acid solution as a replacement sulfuric acid solution were investigated. Aluminum alloy 6061 was used as the base material to produce the hard anodizing; this process was carried out in a citric and sulfuric acid solution, applying current densities 3 and 4.5 A/cm2 and subsequently exposed to 3.5 wt. % NaCl solution. Microstructure and mechanical properties of the anodizing material were characterized by scanning electron microscopy (SEM) and Vickers microhardness (HV). Corrosion behavior of the hard-anodized material it was carried out with electrochemical techniques as cyclic potentiodynamic polarization (CPP) and electrochemical impedance spectroscopy (EIS) respectively. Results obtained indicated that all samples anodized in citric acid sol...
Coatings, 2021
The aim of this work was to evaluate the corrosion behavior of the AA2055 Aluminum-lithium alloy ... more The aim of this work was to evaluate the corrosion behavior of the AA2055 Aluminum-lithium alloy anodized in a sulfuric acid (H2SO4) bath, varying the current density of 0.19 and 1 A·cm−2 and why the sealing solution was water (H2O) and sodium dichromate (Na2Cr2O7). Anodized samples were exposed to a 10 vol.% H2SO4 solution and the electrochemical technique used was electrochemical impedance spectroscopy. Scanning electron microscopy and X-ray photoelectron spectroscopy were employed to characterization of the anodizing layer, determinate morphology and thickness of coatings. The Na2Cr2O7 sealing solution tends to increase the charge transfer resistance and produces a more homogeneous and compact passive oxide layer, and imparts a corrosion inhibition protection to the AA2055. SEM observations indicated that the morphology and thickness of the anodic films formed on AA2055 aluminum-lithium alloy anodized have the best results for both current densities.
Water, 2020
The increasing population and urban sprawl will continue to add significant pressure to natural r... more The increasing population and urban sprawl will continue to add significant pressure to natural resources in arid and semi-arid zones. This study evaluates the theoretical effectiveness of adapting resilient strategies such as water conservation and green infrastructure to mitigate the water scarcity faced by the inhabitants of a residential area with a semi-arid climate. Three scenarios were analyzed at a micro-basin level to determine the mitigation of surface runoff and the volume that can be theoretically intercepted for further use: (a) unaltered natural watershed (scenario 1), (b) currently urbanized watershed (scenario 2), and (c) watershed adapted with resilient strategies (scenario 3). For this last scenario, the annual usable volume of rainwater intercepted on the dwelling rooftops was obtained. The runoff and peak flow in the natural watershed were lower than in the other two scenarios. In contrast, a decrease in the runoff was observed in scenario 3 concerning scenario 2...
Materials, 2020
Novel green concrete (GC) admixtures containing 50% and 100% recycled coarse aggregate (RCA) were... more Novel green concrete (GC) admixtures containing 50% and 100% recycled coarse aggregate (RCA) were manufactured according to the ACI 211.1 standard. The GC samples were reinforced with AISI 1080 carbon steel and AISI 304 stainless steel. Concrete samples were exposed to 3.5 wt.% Na2SO4 and control (DI-water) solutions. Electrochemical testing was assessed by corrosion potential (Ecorr) according to the ASTM C-876-15 standard and a linear polarization resistance (LPR) technique following ASTM G59-14. The compressive strength of the fully substituted GC decreased 51.5% compared to the control sample. Improved corrosion behavior was found for the specimens reinforced with AISI 304 SS; the corrosion current density (icorr) values of the fully substituted GC were found to be 0.01894 µA/cm2 after Day 364, a value associated with negligible corrosion. The 50% RCA specimen shows good corrosion behavior as well as a reduction in environmental impact. Although having lower mechanical propertie...
Journal of Environmental Management, 2019
Permeable pavements are an efficient urban runoff (UR) management solution that also improve wate... more Permeable pavements are an efficient urban runoff (UR) management solution that also improve water quality. In this work, a photocatalytic layer of Fe 2 O 3 nanoparticles (NP) was incorporated into permeable concrete to evaluate its impact on the removal of several microbiological (Escherichia coli, Pseudomonas aeruginosa, Aeromonas hydrophila, and Enterococcus faecalis) and physicochemical (N-NH 4 + , N-NO 3-, phenol, PO 4 3− , Fe, Mn, and Pb) pollutants. First, permeable concrete samples were created with sufficient compressive strength and hydraulic conductivity for light traffic. The test samples were then coated with a mixture containing either 3% or 5% Fe 2 O 3 NP by cement weight. Control samples were prepared without NP. Scanning electron microscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy analyses showed that the nanoparticles remained unaltered on the concrete's surface. Synthetic URs simulating the microbiological or physicochemical composition of real UR were applied to the samples to evaluate their pollutant removal efficiencies. The depollution performances of the test (with 3% and 5% Fe 2 O 3 NP) and control samples were statistically compared. The test samples (3% NP, 5% NP, and the controls) significantly modified (p < 0.05) most of the measured variables (i.e., the concentrations of E. coli, A. hydrophila, PO 4 3− , Fe, Mn, and Pb) in the synthetic URs. Unexpectedly, the test samples (with 3% or 5% Fe 2 O 3 NP) did not significantly remove (p > 0.05) some pollutants prone to oxidation, such as phenol or ammonium. However, the 5% NP sample significantly enhanced Mn removal. In general, the decontamination performances of the concrete samples with Fe 2 O 3 NP were not influenced by the nanoparticles; thus, they did not appear to add value to the generated permeable concrete. Nevertheless, our results indicate the considerable benefits of implementing permeable concrete to improve the quality of UR.
Water, 2017
This paper deals with the design of a bioretention cell and an infiltration trench in a semi-arid... more This paper deals with the design of a bioretention cell and an infiltration trench in a semi-arid micro watershed. The study area was analyzed by characteristics such as slope changes (S), direction and maximum length of the urban runoff (L), and soil use (runoff coefficient, R c). The bioretention cell was designed by the calculation of variables such as drainage area (A), concentration time (T c), rainfall intensity (i), maximum peak drained (Q max), inlet and outlet runoff (Q a and Q out , respectively), temperature (T), evaporation (Ev), potential evapotranspiration (PE m), consumptive use (U) for tolerant plants to semi-arid climates, and soil infiltration capacity (Inf). To design the infiltration trench, only T c , Q max , and i were taken into account. The results showed that the designed bioretention cell could retain between 5.37% and 2.25% of runoff volume. As the efficiency of the bioretention cell can be defined by the need for additional irrigation, our results showed that the cell is inefficient in some of the dry months (November and December), even in years characterized by abundant rainfall. Besides, it was shown that the designed infiltration trench could store or infiltrate the water from typical rain events. Based on these results, it is the implementation of more Low-Impact Development (LID) for runoff management in the study area is recommended.
Materials, 2021
Corrosion of steel reinforcement is the major factor that limits the durability and serviceabilit... more Corrosion of steel reinforcement is the major factor that limits the durability and serviceability performance of reinforced concrete structures. Impressed current cathodic protection (ICCP) is a widely used method to protect steel reinforcements against corrosion. This research aimed to study the effect of cathodic protection on reinforced concrete with fly ash using electrochemical noise (EN). Two types of reinforced concrete mixtures were manufactured; 100% Ordinary Portland Cement (OCP) and replacing 15% of cement using fly ash (OCPFA). The specimens were under-designed protected conditions (−1000 ≤ E ≤ −850 mV vs. Ag/AgCl) and cathodic overprotection (E < −1000 mV vs. Ag/AgCl) by impressed current, and specimens concrete were immersed in a 3.5 wt.% sodium chloride (NaCl) Solution. The analysis of electrochemical noise-time series showed that the mixtures microstructure influenced the corrosion process. Transients of uniform corrosion were observed in the specimens elaborated...
Materials, 2021
OPEN ACCESS / Free download: https://doi.org/10.3390/ma14092438 Corrosion of steel reinforcemen... more OPEN ACCESS / Free download: https://doi.org/10.3390/ma14092438
Corrosion of steel reinforcement is the major factor that limits the durability and serviceability performance of reinforced concrete structures. Impressed current cathodic protection (ICCP) is a widely used method to protect steel reinforcements against corrosion. This research aimed to study the effect of cathodic protection on reinforced concrete with fly ash using electrochemical noise (EN). Two types of reinforced concrete mixtures were manufactured; 100% Ordinary Portland Cement (OCP) and replacing 15% of cement using fly ash (OCPFA). The specimens were under-designed protected conditions (1000 E 850 mV vs. Ag/AgCl) and cathodic overprotection (E < 1000 mV vs. Ag/AgCl) by impressed current, and specimens concrete were immersed in a 3.5 wt.% sodium chloride (NaCl) Solution. The analysis of electrochemical noise-time series showed that the mixtures microstructure influenced the corrosion process. Transients of uniform corrosion were observed in the specimens elaborated with (OPC), unlike those elaborated with (OPCFA). This phenomenon marked the difference in the concrete matrix’s hydration products, preventing Cl ions flow and showing passive current and potential transients in most specimens
Pädi Boletín Científico de Ciencias Básicas e Ingenierías del ICBI
Estimadas y estimados lectores El desarrollo humano sostenible es un concepto que implica mejorar... more Estimadas y estimados lectores El desarrollo humano sostenible es un concepto que implica mejorar la calidad de vida de las personas y satisfacer sus necesidades presentes sin comprometer la capacidad de las generaciones futuras para satisfacer sus propias necesidades. Aplicar técnicas de ingeniería industrial, arquitectura, urbanismo e ingeniería civil en el contexto del desarrollo humano sostenible implica diseñar, planificar y ejecutar proyectos y procesos de manera que promuevan la sostenibilidad ambiental, social y económica. Las disciplinas de la ingeniería industrial, arquitectura e ingeniería civil desempeñan un papel crucial en la planificación y ejecución de proyectos que promuevan la sostenibilidad en términos ambientales, sociales y económicos. En el entorno del desarrollo sustentable el Área Académica de Ingeniería y Arquitectura (AAIyA) manifiesta mediante la Edición Vol. 11 No. Especial 3 (2023), los 22 trabajos desarrollados y aceptados conforme a las siguientes temá...
Pädi Boletín Científico de Ciencias Básicas e Ingenierías del ICBI
La insostenibilidad del crecimiento urbano demanda gran cantidad de recursos naturales. Una opció... more La insostenibilidad del crecimiento urbano demanda gran cantidad de recursos naturales. Una opción para mitigar este gran consumo es el reúso de residuos de la construcción y demolición en sustitución del cemento y agregados. Se diseñó y construyó un muro verde con concreto ecológico; éste consistió en 10% de concreto triturado en sustitución del cemento y 30% de vidrio en lugar de arena. El relleno de sus macetas contiene suelo vegetal, concreto triturado que sustituyó a las gravas y tabique rojo triturado en lugar de arena. Se determinó que el muro verde ecológico es 7.37% más económico que uno fabricado con materiales naturales. El relleno de las macetas representó 72.08% de ahorro, mientras que el concreto ecológico sólo un 6.1%, dado que el cemento es el material más costoso y se sustituyó únicamente un 10% de la cantidad necesaria. Se concluye que los residuos de la construcción y demolición son una opción económicamente viable para reducir el consumo de recursos naturales com...
Metals
Aluminum and its alloys find widespread applications across diverse industries such as the automo... more Aluminum and its alloys find widespread applications across diverse industries such as the automotive, construction, and aeronautics industries. When these alloys come into contact with ambient air, an Al2O3 thin oxide layer is naturally formed, typically measuring 2 to 4 nm and exhibiting remarkable hardness and protective qualities, rendering the alloys corrosion-resistant in specific atmospheric and chemical environments. This study aimed to characterize the electrochemical behaviors of anodized AA2024 and AA7075 alloys within a complex three-component electrolyte composed of tartaric–phosphoric–sulfuric acid (TPSA) solutions. The anodized specimens were subsequently exposed to 3.5 wt.% NaCl solution at room temperature, and their electrochemical performances were meticulously evaluated using an electrochemical noise (EN) analysis in accordance with ASTM G-199, respectively. In the EN, three methods of data analysis were used: the time domain analysis (chaos analysis: application...
International Journal of Electrochemical Science, Nov 1, 2019
This work presents an electrochemical evaluation of a proposed mucilage-based corrosion-resistant... more This work presents an electrochemical evaluation of a proposed mucilage-based corrosion-resistant hybrid coating. The process started with the extraction of mucilage from Opuntia streptacantha and the formulation of 4 coatings containing 0.2, 0.3, 0.4 and 0.5 g of mucilage. The process continued with the coating of rebars through immersion. The rebars were allowed to dry, and then the coating thickness was measured by ultrasound. Optical micrographs were used to characterize the hybrid coating conditions after their evaluation. Working specimens were evaluated using electrochemical impedance spectroscopy and potentiodynamic polarization curves after 24 hours of immersion in a 3.5 wt.% NaCl solution. The mucilage-based hybrid coating reveals enhanced corrosion protection compared to steel without a coating. The obtained results show that the hybrid coating has favorable properties as a barrier due to its ability to obstruct the diffusion of aggressive species by trapping them in the coating structure, which avoids their adsorption on the metallic surface. This effect is due to the homogeneity of the mucilage in the coating, which acts as a corrosion inhibitor due to its semipermeable behavior, where only water molecules flow through its pores, showing promising results as a corrosion-resistant coating.
Sustainability, Dec 7, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Metals
Titanium alloys present superior electrochemical properties due to the generation of the TiO2 pas... more Titanium alloys present superior electrochemical properties due to the generation of the TiO2 passive layer. The ability to generate an oxide passive layer depends on the anodized alloy. This work mainly studies the corrosion resistance of the alloys Ti-6Al-2Sn-4Zr-2Mo and Ti-6Al-4V anodized in NaOH and KOH at 1 M and 0.025 A/cm2 of current density. The electrochemical techniques were performed in a conventional three-electrode cell exposed to electrolytes of NaCl and H2SO4. Based on ASTM-G61 and G199, cyclic potentiodynamic polarization (CPP) and electrochemical noise (EN) techniques were used. The results indicated that Ti-6Al-2Sn-4Zr-2Mo anodized on NaOH presented a higher passivity range than anodized on KOH, relating to the high reactivity of Na+ ions. The former anodized alloy also demonstrated a higher passive layer rupture potential. In EN, the results showed that Ti-6Al-4V anodized in KOH presented a trend toward a localized process due to the heterogeneity of anodized poro...
Tópicos de Investigación en Ciencias de la Tierra y Materiales
En este trabajo de investigación se estudia una alternativa de reutilización de materiales de des... more En este trabajo de investigación se estudia una alternativa de reutilización de materiales de desecho industrial en concreto reforzado buscando determinar parámetros experimentales de resistencia a la corrosión de los distintos sistemas de concreto, en comparación a un concreto reforzado convencional. El uso de la técnica de espectroscopia de impedancia electroquímica muestra que la interacción del jal como cementante no modifica el proceso de corrosión, pues se observa que el uso de residuo minero hasta un 10% no favorece la llegada de los agentes corrosivos a la superficie de la varilla de refuerzo en el concreto comparado a un sistema convencional. Los valores de Rp son muy similares para los distintos sistemas. La interacción de cloruros con el metal se ve aumentada al usar 15% en la dosificación de jal como cementante, modificando considerablemente la velocidad de corrosión del sistema. El concreto elaborado con jal como cementante tiene un comportamiento electroquímico y mecán...
Materials
In the aeronautical industry, Al-Cu alloys are used as a structural material in the manufacturing... more In the aeronautical industry, Al-Cu alloys are used as a structural material in the manufacturing of commercial aircraft due to their high mechanical properties and low density. One of the main issues with these Al-Cu alloy systems is their low corrosion resistance in aggressive substances; as a result, Al-Cu alloys are electrochemically treated by anodizing processes to increase their corrosion resistance. Hard anodizing realized on AA2024 was performed in citric and sulfuric acid solutions for 60 min with constant stirring using current densities 3 and 4.5 A/dm2. After anodizing, a 60 min sealing procedure in water at 95 °C was performed. Scanning electron microscopy (SEM) and Vickers microhardness (HV) measurements were used to characterize the microstructure and mechanical properties of the hard anodizing material. Electrochemical corrosion was carried out using cyclic potentiodynamic polarization curves (CPP) and electrochemical impedance spectroscopy (EIS) in a 3.5 wt. % NaCl ...
Energy Exploration & Exploitation
This research targets to present a case study on the annual comparative assessment of photovoltai... more This research targets to present a case study on the annual comparative assessment of photovoltaic thermal collectors (PV/T) by using water and Ag/water nanofluid for five different cities in Pakistan. The assessment is conducted at monthly, daily, and hourly resolutions. PV/T collector is imitated through a set of energy balance based physical models which are solved numerically for two working fluids (i.e. water and Ag/water nanofluid) in a yearly simulation format (with hourly, daily, and monthly predictions) for five major cities of Pakistan (Taxila, Peshawar, Multan, Lahore, and Karachi). Detailed comparative assessment is carried out based on the performance indicators such as electrical efficiency, thermal efficiency, heat gain, and net electricity power generation. In the results section, hourly, daily, and monthly patterns of performance indicators using water and Ag/water nanofluid are reported, followed by a comparative study between the different cities having different ...
Pädi Boletín Científico de Ciencias Básicas e Ingenierías del ICBI
Una tendencia en el área de la edificación es elaborar elementos constructivos con material de de... more Una tendencia en el área de la edificación es elaborar elementos constructivos con material de desecho diversos, mostrando buenos resultados en pruebas físicas experimentales en comparación con prototipos convencionales. En este trabajo se elaboraron tabicones de concreto modificados sustituyendo un porcentaje de material pétreo por polímero Noryl (poli óxido de fenileno). Un punto importante para considerar en el uso de este tipo de elementos es la prueba de carbonatación, la cual sirve como instrumento para simular de forma acelerada el daño por carbonatación en los especímenes sometidos a un ambiente agresivo. El objetivo de esta investigación fue analizar los perfiles de carbonatación de los distintos especímenes con la prueba de fenolftaleína y medición de pH. Los resultados muestran una disminución en el proceso de carbonatación de los especímenes modificados en comparación con los tabicones comerciales.
Pädi Boletín Científico de Ciencias Básicas e Ingenierías del ICBI
La resistencia a la compresión de mezclas de concreto se consigue al diseñar sistemas que cumplan... more La resistencia a la compresión de mezclas de concreto se consigue al diseñar sistemas que cumplan con propiedades mecánicas y de durabilidad establecidas por normas nacionales e internacionales. En este trabajo se propone un elemento actuador de carga personalizado en la generatriz, tanto en la parte superior e inferior de la celda para tener mejor distribución de carga en el espécimen y ejercer un apoyo uniforme en la sección de contacto para el ensayo de tracción indirecta. En este proyecto se diseñó y manufacturó un dispositivo que podrá servir como instrumentación de la prensa marca Controls modC-43C04 para dar servicio a probetas, en las cuales el concreto es sometido a esfuerzos de tensión con mayor intensidad, donde se espera que el acero de refuerzo sea quien actúe al absorber estos esfuerzos. A través de las pruebas de mecánicas se estableció que la celda cumple con un diseño funcional y con las necesidades de la prensa para la que fue adaptada.
Metals, 2021
Hard-anodized is a widely used method in the aeronautical sector to improve aluminum alloys abras... more Hard-anodized is a widely used method in the aeronautical sector to improve aluminum alloys abrasion and corrosion resistance. Aim of this work was to characterize the mechanical properties and resistance hard-anodized aluminum 6061 in citric acid solution as a replacement sulfuric acid solution were investigated. Aluminum alloy 6061 was used as the base material to produce the hard anodizing; this process was carried out in a citric and sulfuric acid solution, applying current densities 3 and 4.5 A/cm2 and subsequently exposed to 3.5 wt. % NaCl solution. Microstructure and mechanical properties of the anodizing material were characterized by scanning electron microscopy (SEM) and Vickers microhardness (HV). Corrosion behavior of the hard-anodized material it was carried out with electrochemical techniques as cyclic potentiodynamic polarization (CPP) and electrochemical impedance spectroscopy (EIS) respectively. Results obtained indicated that all samples anodized in citric acid sol...
Coatings, 2021
The aim of this work was to evaluate the corrosion behavior of the AA2055 Aluminum-lithium alloy ... more The aim of this work was to evaluate the corrosion behavior of the AA2055 Aluminum-lithium alloy anodized in a sulfuric acid (H2SO4) bath, varying the current density of 0.19 and 1 A·cm−2 and why the sealing solution was water (H2O) and sodium dichromate (Na2Cr2O7). Anodized samples were exposed to a 10 vol.% H2SO4 solution and the electrochemical technique used was electrochemical impedance spectroscopy. Scanning electron microscopy and X-ray photoelectron spectroscopy were employed to characterization of the anodizing layer, determinate morphology and thickness of coatings. The Na2Cr2O7 sealing solution tends to increase the charge transfer resistance and produces a more homogeneous and compact passive oxide layer, and imparts a corrosion inhibition protection to the AA2055. SEM observations indicated that the morphology and thickness of the anodic films formed on AA2055 aluminum-lithium alloy anodized have the best results for both current densities.
Water, 2020
The increasing population and urban sprawl will continue to add significant pressure to natural r... more The increasing population and urban sprawl will continue to add significant pressure to natural resources in arid and semi-arid zones. This study evaluates the theoretical effectiveness of adapting resilient strategies such as water conservation and green infrastructure to mitigate the water scarcity faced by the inhabitants of a residential area with a semi-arid climate. Three scenarios were analyzed at a micro-basin level to determine the mitigation of surface runoff and the volume that can be theoretically intercepted for further use: (a) unaltered natural watershed (scenario 1), (b) currently urbanized watershed (scenario 2), and (c) watershed adapted with resilient strategies (scenario 3). For this last scenario, the annual usable volume of rainwater intercepted on the dwelling rooftops was obtained. The runoff and peak flow in the natural watershed were lower than in the other two scenarios. In contrast, a decrease in the runoff was observed in scenario 3 concerning scenario 2...
Materials, 2020
Novel green concrete (GC) admixtures containing 50% and 100% recycled coarse aggregate (RCA) were... more Novel green concrete (GC) admixtures containing 50% and 100% recycled coarse aggregate (RCA) were manufactured according to the ACI 211.1 standard. The GC samples were reinforced with AISI 1080 carbon steel and AISI 304 stainless steel. Concrete samples were exposed to 3.5 wt.% Na2SO4 and control (DI-water) solutions. Electrochemical testing was assessed by corrosion potential (Ecorr) according to the ASTM C-876-15 standard and a linear polarization resistance (LPR) technique following ASTM G59-14. The compressive strength of the fully substituted GC decreased 51.5% compared to the control sample. Improved corrosion behavior was found for the specimens reinforced with AISI 304 SS; the corrosion current density (icorr) values of the fully substituted GC were found to be 0.01894 µA/cm2 after Day 364, a value associated with negligible corrosion. The 50% RCA specimen shows good corrosion behavior as well as a reduction in environmental impact. Although having lower mechanical propertie...
Journal of Environmental Management, 2019
Permeable pavements are an efficient urban runoff (UR) management solution that also improve wate... more Permeable pavements are an efficient urban runoff (UR) management solution that also improve water quality. In this work, a photocatalytic layer of Fe 2 O 3 nanoparticles (NP) was incorporated into permeable concrete to evaluate its impact on the removal of several microbiological (Escherichia coli, Pseudomonas aeruginosa, Aeromonas hydrophila, and Enterococcus faecalis) and physicochemical (N-NH 4 + , N-NO 3-, phenol, PO 4 3− , Fe, Mn, and Pb) pollutants. First, permeable concrete samples were created with sufficient compressive strength and hydraulic conductivity for light traffic. The test samples were then coated with a mixture containing either 3% or 5% Fe 2 O 3 NP by cement weight. Control samples were prepared without NP. Scanning electron microscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy analyses showed that the nanoparticles remained unaltered on the concrete's surface. Synthetic URs simulating the microbiological or physicochemical composition of real UR were applied to the samples to evaluate their pollutant removal efficiencies. The depollution performances of the test (with 3% and 5% Fe 2 O 3 NP) and control samples were statistically compared. The test samples (3% NP, 5% NP, and the controls) significantly modified (p < 0.05) most of the measured variables (i.e., the concentrations of E. coli, A. hydrophila, PO 4 3− , Fe, Mn, and Pb) in the synthetic URs. Unexpectedly, the test samples (with 3% or 5% Fe 2 O 3 NP) did not significantly remove (p > 0.05) some pollutants prone to oxidation, such as phenol or ammonium. However, the 5% NP sample significantly enhanced Mn removal. In general, the decontamination performances of the concrete samples with Fe 2 O 3 NP were not influenced by the nanoparticles; thus, they did not appear to add value to the generated permeable concrete. Nevertheless, our results indicate the considerable benefits of implementing permeable concrete to improve the quality of UR.
Water, 2017
This paper deals with the design of a bioretention cell and an infiltration trench in a semi-arid... more This paper deals with the design of a bioretention cell and an infiltration trench in a semi-arid micro watershed. The study area was analyzed by characteristics such as slope changes (S), direction and maximum length of the urban runoff (L), and soil use (runoff coefficient, R c). The bioretention cell was designed by the calculation of variables such as drainage area (A), concentration time (T c), rainfall intensity (i), maximum peak drained (Q max), inlet and outlet runoff (Q a and Q out , respectively), temperature (T), evaporation (Ev), potential evapotranspiration (PE m), consumptive use (U) for tolerant plants to semi-arid climates, and soil infiltration capacity (Inf). To design the infiltration trench, only T c , Q max , and i were taken into account. The results showed that the designed bioretention cell could retain between 5.37% and 2.25% of runoff volume. As the efficiency of the bioretention cell can be defined by the need for additional irrigation, our results showed that the cell is inefficient in some of the dry months (November and December), even in years characterized by abundant rainfall. Besides, it was shown that the designed infiltration trench could store or infiltrate the water from typical rain events. Based on these results, it is the implementation of more Low-Impact Development (LID) for runoff management in the study area is recommended.
Materials, 2021
Corrosion of steel reinforcement is the major factor that limits the durability and serviceabilit... more Corrosion of steel reinforcement is the major factor that limits the durability and serviceability performance of reinforced concrete structures. Impressed current cathodic protection (ICCP) is a widely used method to protect steel reinforcements against corrosion. This research aimed to study the effect of cathodic protection on reinforced concrete with fly ash using electrochemical noise (EN). Two types of reinforced concrete mixtures were manufactured; 100% Ordinary Portland Cement (OCP) and replacing 15% of cement using fly ash (OCPFA). The specimens were under-designed protected conditions (−1000 ≤ E ≤ −850 mV vs. Ag/AgCl) and cathodic overprotection (E < −1000 mV vs. Ag/AgCl) by impressed current, and specimens concrete were immersed in a 3.5 wt.% sodium chloride (NaCl) Solution. The analysis of electrochemical noise-time series showed that the mixtures microstructure influenced the corrosion process. Transients of uniform corrosion were observed in the specimens elaborated...
Materials, 2021
OPEN ACCESS / Free download: https://doi.org/10.3390/ma14092438 Corrosion of steel reinforcemen... more OPEN ACCESS / Free download: https://doi.org/10.3390/ma14092438
Corrosion of steel reinforcement is the major factor that limits the durability and serviceability performance of reinforced concrete structures. Impressed current cathodic protection (ICCP) is a widely used method to protect steel reinforcements against corrosion. This research aimed to study the effect of cathodic protection on reinforced concrete with fly ash using electrochemical noise (EN). Two types of reinforced concrete mixtures were manufactured; 100% Ordinary Portland Cement (OCP) and replacing 15% of cement using fly ash (OCPFA). The specimens were under-designed protected conditions (1000 E 850 mV vs. Ag/AgCl) and cathodic overprotection (E < 1000 mV vs. Ag/AgCl) by impressed current, and specimens concrete were immersed in a 3.5 wt.% sodium chloride (NaCl) Solution. The analysis of electrochemical noise-time series showed that the mixtures microstructure influenced the corrosion process. Transients of uniform corrosion were observed in the specimens elaborated with (OPC), unlike those elaborated with (OPCFA). This phenomenon marked the difference in the concrete matrix’s hydration products, preventing Cl ions flow and showing passive current and potential transients in most specimens