Pub Date : 2018-10-09DOI: 10.17533/UDEA.REDIN.N89A08
S. Leal-Marin, H. Estupiñán-Duran
The Ti6Al4V presented a natural oxide layer that increased the corrosion resistance of the material but decreased the physicochemical compatibility with the bone tissue. The use of polymeric coatings on Ti6Al4V allows the creation of an interface that promotes osseointegration and antibacterial activity. The objective of this work was to analyze a coating on Ti6Al4V obtained by dip-coating with a mixture of chitosan, polycaprolactone, and silver. The synergy between chitosan and silver allows the polymeric matrix to be retained and to enhance the coating’s mechanical-structural functions, integrating bone cells and serving as antibacterial agents. Coating morphology was assessed by scanning electron microscopy (SEM) and the distribution of chemical elements was determined by energy dispersive spectroscopy (EDS). Confocal Raman spectroscopy was used to evaluate the composition and structure of the coating. Electrical potential distribution, phase distribution and surface topography of surfaces were analyzed using an electrostatic force microscopy. Contact angle measurements were also performed to determine coating wettability.
{"title":"Polycaprolactone- Chitosan- Ag coatings on Ti6Al4V: Critical synergic aspects analyzed by Raman, EFM and contact angle","authors":"S. Leal-Marin, H. Estupiñán-Duran","doi":"10.17533/UDEA.REDIN.N89A08","DOIUrl":"https://doi.org/10.17533/UDEA.REDIN.N89A08","url":null,"abstract":"The Ti6Al4V presented a natural oxide layer that increased the corrosion resistance of the material but decreased the physicochemical compatibility with the bone tissue. The use of polymeric coatings on Ti6Al4V allows the creation of an interface that promotes osseointegration and antibacterial activity. The objective of this work was to analyze a coating on Ti6Al4V obtained by dip-coating with a mixture of chitosan, polycaprolactone, and silver. The synergy between chitosan and silver allows the polymeric matrix to be retained and to enhance the coating’s mechanical-structural functions, integrating bone cells and serving as antibacterial agents. Coating morphology was assessed by scanning electron microscopy (SEM) and the distribution of chemical elements was determined by energy dispersive spectroscopy (EDS). Confocal Raman spectroscopy was used to evaluate the composition and structure of the coating. Electrical potential distribution, phase distribution and surface topography of surfaces were analyzed using an electrostatic force microscopy. Contact angle measurements were also performed to determine coating wettability.","PeriodicalId":21428,"journal":{"name":"Revista Facultad De Ingenieria-universidad De Antioquia","volume":"18 1","pages":"59-67"},"PeriodicalIF":1.0,"publicationDate":"2018-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89549459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-10-03DOI: 10.17533/UDEA.REDIN.N89A07
A. Garcés-Ruiz
This paper presents a generalized model for small signal stability in dc microgrids considering electric vehicles. The proposed model considers four type of terminals, namely: constant power, constant voltage, constant current and constant impedance. A Newton-Raphson methodology is used to calculate the operation point of the microgrid and a sensitivity analysis is also presented. Some general features of the dc microgrid based on the intrinsic characteristics of the model are presented. Simulation results on different type of microgrids show the proposed small signal model is accurate compared to dynamical simulations.
{"title":"Small-signal stability analysis of DC microgrids considering electric vehicles","authors":"A. Garcés-Ruiz","doi":"10.17533/UDEA.REDIN.N89A07","DOIUrl":"https://doi.org/10.17533/UDEA.REDIN.N89A07","url":null,"abstract":"This paper presents a generalized model for small signal stability in dc microgrids considering electric vehicles. The proposed model considers four type of terminals, namely: constant power, constant voltage, constant current and constant impedance. A Newton-Raphson methodology is used to calculate the operation point of the microgrid and a sensitivity analysis is also presented. Some general features of the dc microgrid based on the intrinsic characteristics of the model are presented. Simulation results on different type of microgrids show the proposed small signal model is accurate compared to dynamical simulations.","PeriodicalId":21428,"journal":{"name":"Revista Facultad De Ingenieria-universidad De Antioquia","volume":"111 1","pages":"52-58"},"PeriodicalIF":1.0,"publicationDate":"2018-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80661203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-10-02DOI: 10.17533/UDEA.REDIN.N89A02
Sandra Milena Restrepo-Arcila, Alejandro Iván Echavarría-Velásquez, Héctor Darío Sánchez-Londoño, Marco Antonio Giraldo-Cadavid
Since ancient times, gold has been used due to its especial properties. Among those properties are the resistance to corrosion (for being noble), its high electrical and thermal conductivity, and also its conspicuous coloration. Gold has been applied in a diversity of subjects such as economy, jewelry, electronic circuits and odontology. The fascinating properties of gold are likely to improve with the preparation of alloys; among those, the Au-Fe alloys constitute some of the most studied nowadays. In this research, we present our results concerning the microstructure of the Au-Fe and Au-Fe-Co alloys. We fabricated gold based alloys with 25% (weight) Fe and then compared their structure and formability to Au-24.5Fe-0.5Co (% weight) to determine the role of cobalt in the alloy. An induction furnace with controlled atmosphere (argon) and conductor crucibles coated with zirconium silicate was used. The samples were characterized by three processes: as-cast , with heat treatment (HT) at T=900°C (1h and 3h) and as-cast centrifuged .
{"title":"Study of the influence of cobalt in the high formability of the Au-Fe system","authors":"Sandra Milena Restrepo-Arcila, Alejandro Iván Echavarría-Velásquez, Héctor Darío Sánchez-Londoño, Marco Antonio Giraldo-Cadavid","doi":"10.17533/UDEA.REDIN.N89A02","DOIUrl":"https://doi.org/10.17533/UDEA.REDIN.N89A02","url":null,"abstract":"Since ancient times, gold has been used due to its especial properties. Among those properties are the resistance to corrosion (for being noble), its high electrical and thermal conductivity, and also its conspicuous coloration. Gold has been applied in a diversity of subjects such as economy, jewelry, electronic circuits and odontology. The fascinating properties of gold are likely to improve with the preparation of alloys; among those, the Au-Fe alloys constitute some of the most studied nowadays. In this research, we present our results concerning the microstructure of the Au-Fe and Au-Fe-Co alloys. We fabricated gold based alloys with 25% (weight) Fe and then compared their structure and formability to Au-24.5Fe-0.5Co (% weight) to determine the role of cobalt in the alloy. An induction furnace with controlled atmosphere (argon) and conductor crucibles coated with zirconium silicate was used. The samples were characterized by three processes: as-cast , with heat treatment (HT) at T=900°C (1h and 3h) and as-cast centrifuged .","PeriodicalId":21428,"journal":{"name":"Revista Facultad De Ingenieria-universidad De Antioquia","volume":"139 1","pages":"9-15"},"PeriodicalIF":1.0,"publicationDate":"2018-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80534938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Three novel imine-chitosan derivatives were synthesized by condensation of the amino terminals of chitosan and 4-bromomethyl-2-hydroxybenzaldehyde A1, 4-formyl-2-hydroxybenzoic acid A2, and (E)-6-((2-(pyridin-2-yl)hydrazono)methyl)picolinaldehyde A3. Noteworthy, is the aqueous synthesis of imine-chitosan compounds using relatively mild conditions (70 °C) in a green chemistry fashion. The new compounds were characterized by 1H-NMR, FT-IR, elemental analysis, thermal gravimetric analysis (TGA), and differential scanning calorimetry (DSC). A solubility study at different pH values was performed for the three compounds, obtaining very different behaviors when compared to that of the pristine chitosan. Finally, by means of atomic absorption the ability to remove heavy metal ions, such as Pb(II) and Hg(II), was investigated for the imine-chitosan derivatives, which showed a high removal percentage at basic pH (between 8-10) but low removal percentage at pH lower than 5. Additionally, the nature of the substituent determines the solubility of the resulting adducts thus widening the potential applications of chitosan derivatives.
{"title":"New chitosan-imine derivatives: from green chemistry to removal of heavy metals from water","authors":"Vivian Lizeth Triana-Guzmán, Yury Ruiz-Cruz, Elkin Libardo Romero-Peñaloza, Héctor Fabio Zuluaga-Corrales, Manuel Noé Chaur-Valencia","doi":"10.17533/UDEA.REDIN.N89A05","DOIUrl":"https://doi.org/10.17533/UDEA.REDIN.N89A05","url":null,"abstract":"Three novel imine-chitosan derivatives were synthesized by condensation of the amino terminals of chitosan and 4-bromomethyl-2-hydroxybenzaldehyde A1, 4-formyl-2-hydroxybenzoic acid A2, and (E)-6-((2-(pyridin-2-yl)hydrazono)methyl)picolinaldehyde A3. Noteworthy, is the aqueous synthesis of imine-chitosan compounds using relatively mild conditions (70 °C) in a green chemistry fashion. The new compounds were characterized by 1H-NMR, FT-IR, elemental analysis, thermal gravimetric analysis (TGA), and differential scanning calorimetry (DSC). A solubility study at different pH values was performed for the three compounds, obtaining very different behaviors when compared to that of the pristine chitosan. Finally, by means of atomic absorption the ability to remove heavy metal ions, such as Pb(II) and Hg(II), was investigated for the imine-chitosan derivatives, which showed a high removal percentage at basic pH (between 8-10) but low removal percentage at pH lower than 5. Additionally, the nature of the substituent determines the solubility of the resulting adducts thus widening the potential applications of chitosan derivatives.","PeriodicalId":21428,"journal":{"name":"Revista Facultad De Ingenieria-universidad De Antioquia","volume":"11 1","pages":"34-43"},"PeriodicalIF":1.0,"publicationDate":"2018-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79163496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The esterification of nopol with acetic acid to produce nopyl acetate using sulfuric acid as homogeneous catalyst was studied. The reactions were carried out in a batch reactor, at different temperatures (50, 60, 70 and 80 °C), catalyst concentrations (0.0184, 0.0275, 0.0367 and 0.0480 mol L -1 ) and molar ratio of acetic acid to nopol (1: 1, 1:2, 1:3 and 1: 4); the chemical equilibrium composition was measured at those reaction conditions. It was found that the equilibrium composition is a weak function of temperature, equilibrium conversion was 63, 68, 71 and 75% at 50, 60, 70 and 80°C, respectively. The reaction was described with a simple power-law model with a second-order kinetic model for both the forward and the backward reaction, using concentration and activities which were predicted by the Universal Functional group Contribution (UNIFAC) method for considering non-ideal behavior of the liquid phase. The forward reaction rate and the equilibrium constants increased with temperature; the relation of the pre-exponential factor with the catalyst amount was evaluated. The activation energy and pre-exponential factor estimated for the forward reaction using the kinetic model based on concentration, were respectively, 28.08 kJ mol -1 and 11126 L mol -1 h -1 with a concentration of catalyst of 0.0275 M. Using the kinetic model based on activities, the forward reaction rate constant was 28.56 kJ·mol -1 and the k fo,act was 33860 L mol -1 h -1 . The enthalpy (34.90 kJ mol -1 ) and the entropy (0.12 kJ mol -1 K -1 ) of reaction were determined using van’t Hoff equation.
以硫酸为均相催化剂，研究了nopol与乙酸的酯化反应制醋酸nopyl。在间歇反应器中，在不同温度(50、60、70和80℃)、催化剂浓度(0.0184、0.0275、0.0367和0.0480 mol L -1)和乙酸与nopol的摩尔比(1:1、1:2、1:3和1:4)下进行反应;测定了反应条件下的化学平衡组成。结果表明，在50、60、70、80℃的温度下，平衡组分的转化率分别为63、68、71、75%。用一个简单的幂律模型来描述该反应，该反应的正反应和反反应都有一个二级动力学模型，考虑到液相的非理想行为，使用通用官能团贡献(UNIFAC)方法预测的浓度和活度。正反应速率和平衡常数随温度升高而增大;考察了指前因子与催化剂用量的关系。在催化剂浓度为0.0275 m的条件下，基于浓度的动力学模型计算得到正向反应的活化能为28.08 kJ mol -1，指前因子为11126 L mol -1 h -1，反应速率常数为28.56 kJ·mol -1，反应k为33860 L mol -1 h -1。用范霍夫方程计算了反应焓(34.90 kJ mol -1)和熵(0.12 kJ mol -1 K -1)。
{"title":"Kinetics of nopyl acetate synthesis by homogeneously catalyzed esterification of acetic acid with nopol","authors":"Aída Luz Villa-Holguín, Eliana Paola Hurtado-Burbano","doi":"10.17533/UDEA.REDIN.N89A03","DOIUrl":"https://doi.org/10.17533/UDEA.REDIN.N89A03","url":null,"abstract":"The esterification of nopol with acetic acid to produce nopyl acetate using sulfuric acid as homogeneous catalyst was studied. The reactions were carried out in a batch reactor, at different temperatures (50, 60, 70 and 80 °C), catalyst concentrations (0.0184, 0.0275, 0.0367 and 0.0480 mol L -1 ) and molar ratio of acetic acid to nopol (1: 1, 1:2, 1:3 and 1: 4); the chemical equilibrium composition was measured at those reaction conditions. It was found that the equilibrium composition is a weak function of temperature, equilibrium conversion was 63, 68, 71 and 75% at 50, 60, 70 and 80°C, respectively. The reaction was described with a simple power-law model with a second-order kinetic model for both the forward and the backward reaction, using concentration and activities which were predicted by the Universal Functional group Contribution (UNIFAC) method for considering non-ideal behavior of the liquid phase. The forward reaction rate and the equilibrium constants increased with temperature; the relation of the pre-exponential factor with the catalyst amount was evaluated. The activation energy and pre-exponential factor estimated for the forward reaction using the kinetic model based on concentration, were respectively, 28.08 kJ mol -1 and 11126 L mol -1 h -1 with a concentration of catalyst of 0.0275 M. Using the kinetic model based on activities, the forward reaction rate constant was 28.56 kJ·mol -1 and the k fo,act was 33860 L mol -1 h -1 . The enthalpy (34.90 kJ mol -1 ) and the entropy (0.12 kJ mol -1 K -1 ) of reaction were determined using van’t Hoff equation.","PeriodicalId":21428,"journal":{"name":"Revista Facultad De Ingenieria-universidad De Antioquia","volume":"228 1","pages":"16-25"},"PeriodicalIF":1.0,"publicationDate":"2018-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75180544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-10-02DOI: 10.17533/udea.redin.n89a04
D. Pérez-Muñoz, J. Marulanda-Arévalo, C. Moreno-Téllez
This paper presents a comparative study on corrosion protection of low-carbon steel coated with two different painting systems. The first set of samples was coated with an aluminum layer of primer deposited by Electric Arc Thermal Spray (EATS), after which two additional layers of paint were applied, thereby creating an aluminum-painting system; while the second set of samples was coated with the traditional three-layer painting system (zinc-rich layer of primer). Afterwards, all the samples were exposed to the salt spray chamber. The samples were monitored to record their reactions in the corrosive saline environment. Scanning Electron Microscopy (SEM), adhesion and electrochemical corrosion tests were performed to characterize the coatings and report changes in their properties (adhesion, topography and homogeneity), which are related to exposure time. The three-layer painting system barely complied with manufacturer claims on protection time under corrosive conditions; on the other hand, the aluminum-painting system yielded better results by prolonging protection time.
{"title":"Corrosion protection in saline environment of a carbon steel coated (aluminum & three-layer painting system) by eats","authors":"D. Pérez-Muñoz, J. Marulanda-Arévalo, C. Moreno-Téllez","doi":"10.17533/udea.redin.n89a04","DOIUrl":"https://doi.org/10.17533/udea.redin.n89a04","url":null,"abstract":"This paper presents a comparative study on corrosion protection of low-carbon steel coated with two different painting systems. The first set of samples was coated with an aluminum layer of primer deposited by Electric Arc Thermal Spray (EATS), after which two additional layers of paint were applied, thereby creating an aluminum-painting system; while the second set of samples was coated with the traditional three-layer painting system (zinc-rich layer of primer). Afterwards, all the samples were exposed to the salt spray chamber. The samples were monitored to record their reactions in the corrosive saline environment. Scanning Electron Microscopy (SEM), adhesion and electrochemical corrosion tests were performed to characterize the coatings and report changes in their properties (adhesion, topography and homogeneity), which are related to exposure time. The three-layer painting system barely complied with manufacturer claims on protection time under corrosive conditions; on the other hand, the aluminum-painting system yielded better results by prolonging protection time.","PeriodicalId":21428,"journal":{"name":"Revista Facultad De Ingenieria-universidad De Antioquia","volume":"52 1","pages":"26-33"},"PeriodicalIF":1.0,"publicationDate":"2018-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76729962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-06-19DOI: 10.17533/UDEA.REDIN.N87A08
Jonathan Ospino-Pinedo, M. Sánchez, L. G. Matallana-Pérez
This work shows a procedure for modeling and control of level and flow processes. It uses the EMSO simulator to connect to a process by means of a SIMATIC S7-200 PLC as interface for the communication between the process instrumentation and the controller computing system. In order to supervise the variables, a SIMULINK model was connected to a laboratory process module through OPC communication. The model obtained was used in the design of controllers PID and PBSM, which were tested for step disturbances of the set point and an imposed set point trajectory.
{"title":"Modeling and control of processes using the EMSO simulator and SIMATIC PLC as OPC inter-face","authors":"Jonathan Ospino-Pinedo, M. Sánchez, L. G. Matallana-Pérez","doi":"10.17533/UDEA.REDIN.N87A08","DOIUrl":"https://doi.org/10.17533/UDEA.REDIN.N87A08","url":null,"abstract":"This work shows a procedure for modeling and control of level and flow processes. It uses the EMSO simulator to connect to a process by means of a SIMATIC S7-200 PLC as interface for the communication between the process instrumentation and the controller computing system. In order to supervise the variables, a SIMULINK model was connected to a laboratory process module through OPC communication. The model obtained was used in the design of controllers PID and PBSM, which were tested for step disturbances of the set point and an imposed set point trajectory.","PeriodicalId":21428,"journal":{"name":"Revista Facultad De Ingenieria-universidad De Antioquia","volume":"193 1","pages":"58-69"},"PeriodicalIF":1.0,"publicationDate":"2018-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76925899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-05-20DOI: 10.19053/01211129.V27.N48.2018.8017
G. Cuervo-Osorio, Ana María Jiménez-Valencia, Cristian Mosquera-Agualimpia, Diana Marcela Escobar-Sierra
The skeletal system is vulnerable to injuries and bone loss over the years, making the use of autologous or allogeneic implants necessary. However, these implants have complications, such as the limited amount of bone to be extracted and the cell death at the extraction site; hence, biomaterials have been developed as platforms for cell growth (scaffolds). Biomaterials and bones have similar properties that facilitate the integration between the material and the bone tissue, helping the tissue to regenerate. Traditional ceramic implants are hydroxyapatite, but given their low mechanical properties, they have been replaced with better inert ceramics. Therefore, this study aims at manufacturing titanium dioxide scaffolds through various techniques, using collagen, polyvinyl alcohol (PVA), sodium chloride, and corn flour as binders to influence pore size. Scaffolds were characterized by a Scanning Electron Microscope (SEM) and evaluated by compression and degradability tests in a Simulated Body Fluid (SBF). The prepared scaffolds had mechanical behaviors with ranges within the bone parameters; among them, the scaffold obtained by infiltration with 10% PVA presented values of compression strength (6.75 MPa), elastic modulus (0.23 GPa), and porosities (54-67%) closer to the values of the trabecular bone.
{"title":"Manufacture of titanium dioxide scaffolds for medical applications","authors":"G. Cuervo-Osorio, Ana María Jiménez-Valencia, Cristian Mosquera-Agualimpia, Diana Marcela Escobar-Sierra","doi":"10.19053/01211129.V27.N48.2018.8017","DOIUrl":"https://doi.org/10.19053/01211129.V27.N48.2018.8017","url":null,"abstract":"The skeletal system is vulnerable to injuries and bone loss over the years, making the use of autologous or allogeneic implants necessary. However, these implants have complications, such as the limited amount of bone to be extracted and the cell death at the extraction site; hence, biomaterials have been developed as platforms for cell growth (scaffolds). Biomaterials and bones have similar properties that facilitate the integration between the material and the bone tissue, helping the tissue to regenerate. Traditional ceramic implants are hydroxyapatite, but given their low mechanical properties, they have been replaced with better inert ceramics. Therefore, this study aims at manufacturing titanium dioxide scaffolds through various techniques, using collagen, polyvinyl alcohol (PVA), sodium chloride, and corn flour as binders to influence pore size. Scaffolds were characterized by a Scanning Electron Microscope (SEM) and evaluated by compression and degradability tests in a Simulated Body Fluid (SBF). The prepared scaffolds had mechanical behaviors with ranges within the bone parameters; among them, the scaffold obtained by infiltration with 10% PVA presented values of compression strength (6.75 MPa), elastic modulus (0.23 GPa), and porosities (54-67%) closer to the values of the trabecular bone.","PeriodicalId":21428,"journal":{"name":"Revista Facultad De Ingenieria-universidad De Antioquia","volume":"11 1","pages":"17-25"},"PeriodicalIF":1.0,"publicationDate":"2018-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84274329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-05-20DOI: 10.19053/01211129.V27.N48.2018.8016
María Ángeles Arenas-Vara, P. Skeldon, S. Garcia‐Vergara
Copper-enriched layers were developed onto aluminum-copper alloys using alkaline etching in sodium hydroxide, for both, sputter deposited and bulk conditions. Enriched alloys were evaluated by potentiodynamic polarization in sodium chloride solution in order to determine the effect of the enriched layers on the pitting potential of the alloys. Rutherford backscattering spectroscopy was employed to quantify the enrichments and their locations just beneath the alumina-based oxides remaining from the etching. For the sputter deposited aluminum-copper alloys, the results show some scattering of the pitting potential data, and no correlation between pitting potential and the alloy enriched layer. In the case of bulk Al-2wt.%Cu alloy, with the copper in solid-solution, the pitting potential increased for the enriched specimens, indicating also a different pit morphology, with respect to the non-enriched alloy.
{"title":"Effect of copper-enriched layers on localized corrosion of aluminium-copper alloys","authors":"María Ángeles Arenas-Vara, P. Skeldon, S. Garcia‐Vergara","doi":"10.19053/01211129.V27.N48.2018.8016","DOIUrl":"https://doi.org/10.19053/01211129.V27.N48.2018.8016","url":null,"abstract":"Copper-enriched layers were developed onto aluminum-copper alloys using alkaline etching in sodium hydroxide, for both, sputter deposited and bulk conditions. Enriched alloys were evaluated by potentiodynamic polarization in sodium chloride solution in order to determine the effect of the enriched layers on the pitting potential of the alloys. Rutherford backscattering spectroscopy was employed to quantify the enrichments and their locations just beneath the alumina-based oxides remaining from the etching. For the sputter deposited aluminum-copper alloys, the results show some scattering of the pitting potential data, and no correlation between pitting potential and the alloy enriched layer. In the case of bulk Al-2wt.%Cu alloy, with the copper in solid-solution, the pitting potential increased for the enriched specimens, indicating also a different pit morphology, with respect to the non-enriched alloy.","PeriodicalId":21428,"journal":{"name":"Revista Facultad De Ingenieria-universidad De Antioquia","volume":"109 1","pages":"7-15"},"PeriodicalIF":1.0,"publicationDate":"2018-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75870816","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-05-20DOI: 10.19053/01211129.V27.N48.2018.8403
Brayan Esguerra-Prieto, Natalia González-Garzón, Alberto Acosta-López
This article proposes a method for teaching complex numbers and their corresponding operations using mathematical software tools. Initially, the document introduces MATLAB, a paid software, and GeoGebra, a free software. Subsequently, the paper explains the procedure to define the representations of the basic (addition, difference, multiplication and division) and complementary (module and conjugate, roots and polar form) operations of the numerical system of complex numbers, using the two tools and a series of proposed exercises. Finally, the paper highlights the evidenced qualities during the development of the exercises and their transcendence in teaching and learning.
{"title":"Herramientas de software matemático para la enseñanza de números complejos","authors":"Brayan Esguerra-Prieto, Natalia González-Garzón, Alberto Acosta-López","doi":"10.19053/01211129.V27.N48.2018.8403","DOIUrl":"https://doi.org/10.19053/01211129.V27.N48.2018.8403","url":null,"abstract":"This article proposes a method for teaching complex numbers and their corresponding operations using mathematical software tools. Initially, the document introduces MATLAB, a paid software, and GeoGebra, a free software. Subsequently, the paper explains the procedure to define the representations of the basic (addition, difference, multiplication and division) and complementary (module and conjugate, roots and polar form) operations of the numerical system of complex numbers, using the two tools and a series of proposed exercises. Finally, the paper highlights the evidenced qualities during the development of the exercises and their transcendence in teaching and learning.","PeriodicalId":21428,"journal":{"name":"Revista Facultad De Ingenieria-universidad De Antioquia","volume":"126 1","pages":"79-90"},"PeriodicalIF":1.0,"publicationDate":"2018-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89678546","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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