Envíos recientes

Analysis of heat fluxes in ceramic block type building pieces

Sanchez Molina, Jorge | 2021-09-02

In Norte de Santander, Colombia, there is a ceramic cluster made up of 59 companies dedicated to the production of construction materials derived from clay, a vernacular material with a wide extraction potential in the region. Fired clay products in different hollow block presentations represent 15% of industrial production, these construction pieces are low cost and show a high demand in the local masonry market, therefore, their thermo-physical characteristics largely build the thermal envelope of “Cucuteña”. This research comparatively evaluates the thermal behavior of four types of ceramic blocks with different perforations, applying the finite element method in thermal simulations that consider a conductivity of 0.407 W/m°C in the ceramic to establish the influence of the shape on the temperature distribution and heat flow profiles of each piece subjected to environmental conditions of a warm semi-arid climate, with average maximum temperatures of 33 °C and an average maximum solar radiation of 796.8 Wh/m² under extreme climatic conditions in the city of San Jose de Cúcuta, Colombia. The results of the study allow identifying the ceramic block of 6 rectangular holes as the product that, due to its physical characteristics, presents a better alternative to be applied in constructions that seek thermal efficiency.

Tribocorrosion-Resistant Surface for TiO2 as a Function of Load and Sliding Speed

Bautista-Ruiz, Jorge | 2023-02-21

The applications projected in the coatings are in implants with the lower extremities since they require a great load capacity and are essential for walking. Therefore, the use of devices or implants is necessary for recovery, osteosynthesis, and fixation. The tribocorrosive behavior of nanostructured compounds based on titanium oxide with an intermediate layer of gold deposited on titanium substrates was determined. These coatings were obtained using the reactive magnetron sputtering technique. Tribocorrosive properties were evaluated at sliding speeds of 3500 mm/min, 4500 mm/min, 6000 mm/min, 7500 mm/min, and 9000 mm/min with loads of 1 N, 2 N, 3 N, 4 N, and 5 N. The coatings were characterized by X-ray photoemission spectroscopy and X-ray diffraction, and the surface roughness was analyzed by atomic force microscopy. The dual mechanical and electrochemical wear tests were carried out with a potentiostat coupled to a pin on the disk system. The system was in contact with a hanks solution (37 ◦C), which acted as a lubricant. Structural characterization made it possible to identify the TiO2 compound. In the morphological characterization, it was found that the substrate influenced the surface properties of the coatings. The tribological behavior estimated by the wear rates showed less wear at higher load and sliding speeds. It was shown that it is possible to obtain coatings with better electrochemical and tribological performance by controlling the applied load and slip speed variables. In this study, a significant decrease corresponding to 64% was obtained, specifically in the speed of deterioration, and especially for a load of 5 N, depending on the sliding speed that went from 0.2831 mpy (Mils penetration per year) to 3500 mm/min compared to 0.1045 mpy at 9000 mm/min, which is explained by the mechanical blockage induced by the coating.

Effect of Temperature on the Tribological Properties of Hafnium Carbonitrides Coatings

Aperador Chaparro, William Arnulfo | 2023-04-21

For industrial processes in which refractory metals are necessary, hafnium carbonitride exhibits excellent performance due to its high thermal conductivity and resistance to oxidation. In this study, hafnium carbonitride was deposited on Inconel 718 steel and silicon (100) substrates. The objective was to characterize the wear properties as a function of temperature. The layers were deposited by physical vapor deposition (PVD) in an R.F. sputtering magnetron system from carbon targets and high-purity hafnium (99.99%). The wear tests were carried out at temperatures of 100 ◦C, 200 ◦C, 400 ◦C, and 800 ◦C in non-lubricated conditions. The coefficient of friction (COF) was recorded in situ. The heat treatment temperature on coatings is essential in determining anti-wear efficiency. It was determined that high temperatures (800 ◦C) improve resistance to wear. High-resolution XPS spectra were used to detect the chemical states of Hf 4f5/2 and Hf 4f7/2. The 4f5/2 and 4f7/2 binding energy indicates the presence of HfN and HfC. Using the TEM technique in bright field mode allowed us to know the orientation, crystallographic structure and interplanar distances of the HfCN. The topography of the coatings, by AFM, shows uniform grains and very small characteristics that determine the low surface roughness value. The SEM image of the cross-section of the HfCN coating shows homogeneity of the layer; no cracks or deformations are observed.

Geopolymers Based on a Mixture of Steel Slag and Fly Ash, Activated with Rice Husks and Reinforced with Guadua angustifolia Fibers

Aperador Chaparro, William Arnulfo | 2023-08-15

At present, the conservation of the environment represents an objective that everyone wants to achieve. The construction industry has influenced the advancement of alternative materials that comply with sustainable development. In this article, reinforced concrete was obtained by mixing 80% blast furnace slag and 20% fly ash. These concentrations were chosen because they provide the lowest porosity in the cementitious matrix. Rice husk ash was used as an activator. Guadua angustifolia fibers were used to evaluate the mechanical performance of the concrete. The composition of the raw material was determined by X-ray fluorescence, the microstructure of the fibers by AFM, and the SEM technique was used to determine the surface characteristics of guadua fibers and concrete mixes. The structural characterization using XRD, the structure of the molecules of the guadua fiber, and the composition of the mixture’s molecular mixtures were determined by FTIR spectroscopy. Its properties, such as tensile strength and flexural strength, were analyzed. The results indicated that the concrete with the addition of Guadua angustifolia fibers. The results indicated that the concrete with the addition of guadua angustifolia fibers showed the best mechanical behavior. Tensile strength was optimized, establishing values of 2.68 MPa for unreinforced concrete and up to 3.12 MPa for fiber-reinforced concrete. The flexural strength values increase at ages after 28 days due to the pozzolanic reaction generated. Values of 2.8 MPa were obtained for concrete without fiber and 3.5 MPa for concrete reinforced with guadua angustifolia fiber.

Sliding and corrosion wear of magnetron sputtered tio2 films deposited with different argon and oxygen mixtures

Aperador Chaparro, Willian | 2021-06-15

Were produced TiO2 thin coatings prepared, on substrates pure Titanium using a deposition by magnetron sputtering technique, the percentage of oxygen was varied, to study the behavior in terms of friction coefficient corrosive fluids such as those related to the human body. Electrochemical Impedance Spectroscopy (EIS), wear tests with a tribometer, were performed to obtain the tribo-corrosion mechanism of deterioration, taking into account the dual corrosion wear system. The phases were identified by X-ray Photoelectron Spectroscopy (XPS) high resolution. It is determined through the tests performed that the surface treatment has a different effect for each percentage of oxygen influenced by the simulated body environments. The wear performance analysis indicated that the TiO2 film's protection had increased as the percentage of oxygen in the gas mixture (Ar/O2) varied and other synthesis parameters such as deposition time, target power, and substrate temperature remained constant.

SYNERGISTIC CORROSION-WEAR EFFECT IN AUSTENITIC POWDER METALLURGICAL STEEL WITH DIFFERENT TITANIUM ADDITIONS

Aperador, w | 2022-01-01

To ascertain the influence of titanium percentage in 316L austenitic steel, titanium percentages varied from 0.5 to 2% aggregated to 316L steel. The powder metallurgy method was used. The powdered material was pressed at 800 MPa and then sintered at 1300°C. The X-ray diffraction (XRD) technique was used to characterize the identification of the phases after the processed mixtures. Wear and tribowear properties were determined by pin on disc tests. Electrochemical polarization curves were used to study corrosion. According to the results of the samples, the corrosion resistance of titanium increased to a percentage of 1.5% due to the formation of the phases generated by the mixture. However, it was determined that the most appropriate percentage is 2%, due to the synergistic mode specifically for wear and corrosion resistance, the mechanism is the most adequate.

Characterization of clay material and rice husk from northeast Colombia

Sanchez Molina, Jorge | 2021-01

This research was to study materials from the region to use them industrially applying the circular economy concept. Clay Material and Rice Husk were evaluated in the manufacture of ceramic products. X-ray Diffraction and X-ray Fluorescence techniques were used to determine the raw materials' chemical and mineralogical composition. Thermal analysis techniques (TG and DTG) were used to complement the study. The XRD results showed an abundance of quartz. The results of the thermal analysis establish significant losses due to calcination. The thermal conductivity was also measured in ceramic specimens made from two types of pastes, one with 100% Clay Material and the other with a 5% substitution for Rice Husk. The results showed a decrease in thermal conductivity in the test tubes with the addition of Rice Husk. Consequently, the Rice Husk as a substitute for the Clay Material allows for ceramic production with thermal efficiency.

Characteristics of refractory bricks used in the coke production kilns in Colombia

Gelves Diaz, John Freddy | 2021-06-04

A study has been carried out on the main physicochemical characteristics of the refractory bricks that are currently used in traditional coke-making kilns in Colombia. Two classes of material (brick) used in this industry were collected, which come from a geographical area of the country that supplies brick to many kiln builders. These materials were characterized by X-ray diffraction and fluorescence, scanning electron microscopy, dilatometry, thermal conductivity, pyroscopic resistance, and percentage of water absorption. The results obtained show that these materials have had very low firing temperatures in the factory, which is evidenced in the dilatometry, microscopy and water absorption percentage data. This characteristic brings with it high firing shrinkages when subjected to high temperatures (> 4% at 1,200 °C). There is a high presence of quartz in the material (40% or more), an aspect that increases the risk of fissure formation. Chemically there is a limited aluminum content (between 22% and 23%) compared to other reference refractories. The onset of fusion of these materials occurs around 1,360 °C. The thermal conductivity obtained can be considered moderate (between 0.634 W⁄mK and 0.760 W⁄mK), thus demonstrating limited applicability as an insulator.

Anticorrosive evaluation of copper-iron mixtures processed by powder metallurgy

Bautista-Ruiz, Jorge | 2021

Through the powder metallurgy process, copper and iron powders were mixed in the proportions Cu between 15% to 75% and iron from 25% to 85% that made up the binary material systems. Material systems were topographically characterized with atomic force microscopy. Corrosion tests were established using potentiodynamic polarization curves. The worn surfaces' characterization was carried out by means of a Confocal Scanning Laser Microscope to complement the study. It was determined that the mixtures' stability and behaviour have different behaviours depending on the evaluated system because the wear system caused, indicating that the phenomenon can be additive. The corrosive phenomenon is dominantly affected by the microstructure of the material. From the results found, it is possible to infer that the best systems evaluated by corrosive contain the highest percentage of copper content. The topographic variation indicates the transition from the active zone to the passive zone of the metal due to electrochemical reactions in the presence of aggressive media.

Wear synergy of copper-iron mixtures processed by powder metallurgy

Operador, W | 2021

Through the powder metallurgy process, copper and iron powders were mixed in the proportions Cu between 15% to 75% and iron from 25% to 85% that made up the binary material systems. The X-ray diffraction technique was used to determine the crystalline structure. Material systems were topographically characterized with optical microscopy. Tribology tests were established using a pin on the disk tribometer. It was determined that the stability of the mixture has different behaviors depending on the evaluated system because the wear system caused, indicating that the phenomenon can be additive. The mixed material is characterized by high friction coefficient and high wear due to the samples' specific properties by increasing the amount of iron in the mixture. The systems analyzed indicate that mechanical degradation was mainly reduced. Dimensional variation of the study specimens was evidenced due to the influence of copper in the system. Only the austenitic structure of the steel was observed, which indicates a complete diffusion of the copper.

Utilization of agro-industrial waste to improve thermal behavior of products made of fired clay for traditional masonry

Sanchez Molina, Jorge | 2021-08-09

The reutilization of agro-industrial waste in the manufacture of fired clay products is a sustainable strategy that aims at the circular economy. The most known waste in Norte de Santander, Colombia, are coffee husk and rice husk. For this reason, this research studies the thermal impact of their insulating properties in traditional masonry products made of fired clay to be considered as insulating additives. The methodology involves the simulation of heat transfer and heat flux of the multiperforated brick and H10 block manufactured in mixtures of 100% clay and 95% clay and 5% additive to wastes in North Santander, Colombia, in the software ANSYS under the finite element method in extreme conditions of San José de Cúcuta. The results demonstrate that the residues of rice husk and coffee husk act as insulating technological nutrients with a reduction of temperatures of the interior surfaces of the products between 0.22 °C and 0.88 °C, respectively. The reutilization of residual raw materials from alternate construction industries is a sustainable consideration to evaluate new possibilities for the manufacture of products with less embedded energy and, therefore, with a lower carbon footprint than traditional fired clay products.

Effect of layer thickness on anticorrosive performance of 316L steel coated with bismuth-titanium films

GARZÓN AGUDELO, PEDRO | 2021-05

. Bismuth and titanium are elements with remarkable properties and applications in technological developments and in the field of biomedical engineering. The sol-gel method was used to form a bismuth-titanium system, which allowed to establish if it was possible to obtain films with anticorrosive properties on 316L stainless steel. The anticorrosive response was evaluated by means of Tafel curves, defining the parameters to obtain thin and functional films with good tribological properties. The coatings were obtained by the spin coating technique, varying the spin speeds from 3000 rpm to 5000 rpm with monolayer and bilayer systems. More positive values of corrosion potential were obtained when the steel is coated by the films, which implies a lower propensity to corrosion in saline medium, lower corrosion rates and higher potentials are reported for films with higher titanium content, likewise, better efficiency of the films with respect to the uncoated substrate is presented, the higher the titanium content and a strong influence between the calculated efficiencies and the centrifugation speeds is not observed

High-Temperature Corrosion Behavior of Bi3.75La0.25Ti3O12 and Bi3La1Ti3O12 Coating Prepared by rf Magnetron Sputtering

Bautista Ruiz, Jorge | 2022-09-23

: Using the rf magnetron sputtering technique, Bi3.75La0.25Ti3O12 and Bi3La1Ti3O12 coatings were formed and obtained as a thin film on Hastelloy substrates. When subjected to high-temperature conditions, the effect of lanthanum on the anti-corrosive properties of the coatings was investigated. The anti-corrosive response was evaluated by electrochemical impedance spectroscopy and potentiodynamic curves, which are rarely reported. Hot corrosion occurs through the electrochemical mechanism, and more information can be obtained through electrochemical corrosion tests, which are very effective and fast. The electrochemical behavior at high temperatures was studied via molten salt corrosion tests, potentiodynamic polarization curves, and electrochemical impedance spectroscopy. Additionally, the coatings were evaluated via scanning electron microscopy and transmission microscopy to determine their morphology. With X-ray diffraction, the crystallinity of the films was determined. It was determined that the corrosion rate directly correlates with the temperature, attributed to the mechanisms induced by the Na2SO4 and V2O5 salts that generated condensation. As the temperature increases, the density of the corrosion current increases in the thin films of Bi3.75La0.25Ti3O12 and Bi3La1Ti3O12. When comparing the two compounds, it is determined that the increase in lanthanum alters the positive acid character, thus reducing the dissolution of the oxides and increasing protection.

Determination of the efficiency of hafnium carbide and tantalum carbide coatings deposited on exchange membrane fuel cells

Ruiz Madera, C | 2021-10

“Una comunidad, Un Producto” Fortalecimiento del Sector Cerámico Artesanal de Cúcuta en la construcción de su producto identitario

Sanchez Molina, Jorge | 2020-02-02

El proyecto busca fortalecer a las unidades productivas artesanales de la cerámica de Cúcuta y su área metropolitana, mediante el mejoramiento de las etapas del proceso productivo, a través de las siguientes líneas de acción: capacitación y asesoría en procesos productivos, desarrollo de productos, organización, tecnología y uso de derechos de propiedad intelectual. Se destaca que en el proyecto intervienen de forma articulada el Centro de Investigación de Materiales Cerámicos y tres grupos de Investigación de la Universidad Francisco de Paula Santander, en apoyo a organizaciones del sector publico y privado como actores claves en el esfuerzo por el fortalecimiento de la cerámica artesanal en la región, siendo este proyecto considerado como el inicio de un apoyo pertinente y sostenido en el tiempo, mediante alianzas estratégicas.

Effect of the addition of rice husk in technological properties of materials for the manufacture of ceramic

Bautista-Ruiz, Jorge | 2021-06

In this study, the rice husk discarded by the agro-industrial rice company in the department of Norte de Santander (Colombia) was used to replace clay material in the manufacture of tile-type ceramics. The materials were used to make test specimens with the presence of 5%, 10%, 15%, and 20% (weight) of scale and with three different types of grain size (1180 µm, 180 µm, and 75 µm mesh through). The specimens were molded using the extrusion technique. The shaped materials were subjected to different firing temperatures (900 °C, 1000 °C, 1100 °C, 1150 °C, and 1200 °C) to establish correlations between the microstructure/topography of the material and some of the technological properties of the ceramic such as the mechanical resistance to bending, resistance to deep abrasion, percentage of water absorption and linear drying/cooking shrinkage. The results show that proportions higher than 10% of rice husk do not obtain ceramics with ideal technological properties for use as pavement or coating. The best results were obtained when the husk was used at 5% and 180 µm mesh through grain size. The X-ray diffraction analysis of the cooked samples shows significant changes in the proportion of phases formed (test tubes with and without substitution of clay material) as the temperature increases.

Production of electroplated rhenium coatings using pulsating currents

| 2021-06

Rhenium was the most interesting material because it can be oxidized at high temperatures, so it is a promising applicant in biomedical applications. Its high melting point requires techniques such as electro-coating to produce it in thin-film formation, using a current of 40 mA/cm2 , in a cathode pulse and 4 mA/cm2 , in anodic form, the variation in temperature of the acid electrolytic bath being realized in a range of 60 to 85±2 °C. The temperature variation of the samples allowed to correlate their response to the degradation phenomenon. The topographical evaluation using atomic force microscopy on the surface of the samples permitted to indicate that a tendency of the roughness to reduce with the increase of the temperature up to 80 °C existed, an electrochemical evaluation was generated using Tafel polarization curves, immersed in a Ringer's lactate solution with a temperature of 37 °C, has now been subsequently performed using the scanning electron microscope, the surface analysis of the coatings, demonstrating that at deterioration is negligible, but when increasing the temperature to 80 °C, the deterioration is imperceptible when the type of surface damage is unobservable, however in the case of 85 °C the deterioration is observable.

Museums of geological and mining heritage. Case study for El Suspiro mine (Cúcuta, Colombia)

Castro Duque, Yesid | 2021-06

This work provides information on several existing museums in the region of Cúcuta (Colombia), which have elements that can be considered geological or mining heritage. These museums could be integrated into the creation of a mining theme park in conjunction with the closure of the El Suspiro limestone mine. The objective of this study, in addition to disseminating the information, is to show the existing museums at the municipalities of Los Patios and Cúcuta, where there are collections of fossils, minerals and archaeological elements found in the region. Additionally, there are enginery and elements that were used for mining development in the region as well as in the School of Mining Engineering at the Universidad Francisco de Paula Santander (UFPS). The methodology of this study involved an analysis of the topic at global, national and local contexts, visits to the museums and the mine site, as well as photographic records and geo-positioning. It is concluded that it is feasible to implement geotouristic visits at the El Suspiro limestone mine, as well as visits to the existing museums in Agualinda and Vados counties, and the museum of geological and mining heritage of the Universidad Francisco de Paula Santander at Cúcuta, Colombia.

DISEÑO DE UN PRODUCTO DE CONSTRUCCIÓN DE CONCRETO REFORZADO CON FIBRAS DE VIDRIO Y CON FIBRAS A PARTIR DE SUB-PRODUCTOS INDUSTRIALES

Sanchez Molina, Jorge | 2021-08-25

El concreto es un material que ha sido utilizado desde la antigüedad en la construcción de edificaciones que han sobrevivido el paso de los años. El concreto a su vez ha sido foco de investigación por muchos científicos a nivel mundial, quienes tienen como propósito optimizar las propiedades físicas y mecánicas para el mejoramiento continuo del material en cuanto a manejabilidad, resistencia y durabilidad. Diversas fuentes han reportado que desde la antigüedad se hacia el uso de materias primas diferentes a las convencionales (arena, cemento y grava) para la fabricación de concreto, tal es el caso del uso de crin de caballo adicionadas a morteros, y la paja para reforzar ladrillos de barro. En la actualidad, reforzar concreto con hebras o hilos tienen un nombre específico, el cual es conocido como concreto reforzado con fibras. Las fibras pueden ser de muchas procedencias; ya sean artificiales como lo es el caso de las fibras de plástico (polipropileno y el polietileno tereftalato-PET), las fibras de vidrio y las fibras metálicas, de hierro o acero; o también pueden ser fibras de procedencia natural (de origen animal o vegetal), como es el caso de las fibras de bagazo de caña de azúcar, paja, lechuguilla, estopa de coco, plumas de aves, entre otras. El uso de las fibras para reforzar concreto se da con el fin de mejorar ciertas características del concreto, tal como la resistencia a la flexión y la resistencia a la tracción, pero sin dañar propiedades como la densidad, la resistencia a la compresión y el módulo de elasticidad. Además, en muchos casos el uso de fibras se da con el fin de utilizar aquellos desechos y/o sub-productos industriales a los cuales no se les da un correcto manejo y terminan contaminando el medio ambiente. Por lo tanto, el presente proyecto tiene la finalidad de fabricar concreto con fibras de vidrio, las cuales han sido catalogadas por muchos investigadores como las mejores fibras para reforzar concreto, y compararla con fibras naturales a partir de desechos y/o sub-productos industriales, e identificar cuales fibras presentan mejoras en las condiciones del concreto (contrastado con concreto convencional). La investigación hace parte de un desarrollo tecnológico y experimental, es de tipo cuantitativa y descriptiva, ya que la investigación pretende conocer la estructura y la funcionalidad de un concreto especial diseñado con fibras de vidrio y con fibras a partir de sub-productos industriales. Los resultados esperados con el desarrollo del proyecto son los siguientes: formar a dos jóvenes investigadores, los cuales están siendo financiados por MinCiencias a través de la convocatoria 891; generar conocimiento a través de la publicación de un artículo científico en una revista categoría B; y generar la apropiación de conocimiento a través de la participación en la modalidad de ponencia en un evento nacional o internacional.

Mineralogical characterization of zeolites present on basaltic rocks from Combia geological formation, La Pintada (Colombia)

Gelves Diaz, John Freddy | 2016-11

The present study report the presence of natural zeolites, which were found in the andesitic basalts from the Combia geological formation, municipality of La Pintada, Antioquia department (Colombia). The collected samples were characterized using X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy with detector X-ray energy dispersive (SEM/EDX), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and polarized light optical microscopy (PLOM). The results shown the presence of an associated zeolites heulandite group with predominance of heulandite phase rich in calcium and potassium, with prevalence of platy habit and in a lesser extent the habit coffin type, tabular and block were also evidenced. The presence of chabazite, phillipsite and mordenite, were evidenced as minority zeolites phases. Based on the zeolites properties, the phases founded in Combia formation could be an interest materials for technological applications in areas such agriculture, catalysis or gas separation applications. Especially in Colombia this kind of mineral can be important because much of the current consumption is imported from other territories.