High-Temperature Oxidation of Superalloy C-263 of Rings for Aircraft Engines

The present investigation was conducted to study the oxidation kinetics of nickel-based superalloy 263, used in the manufacture of rings for aircraft engines. For carrying out this study, we first conducted microstructural characterization of the pieces using the techniques of optical microscopy, scanning electronic microscopy, and X-ray diffraction. Subsequently, using the thermogravimetric analysis, the kinetic oxidation of the metal was performed in a temperature range between 700 and 1000°C, using atmospheres of O2. The results of the micrographs show the formation of a protective oxide film on the surface of the material in different oxidizing agents. Finally, it was found that the kinetics of high-temperature oxidation of the superalloy C-263 obeys the parabolic rate law

Acantholippia seriphioides : chemical biodiversity of wild populations from the Cuyo Region in Argentina = Acantholippia seriphioides: Biodiversidad química de poblaciones silvestres de la región de Cuyo de la Argentina

Nineteen samples from the aerial parts in bloom of Acantholippia seriphioides (Verbenaceae) were collected in three provinces belonging to the Cuyo region of Argentina. The essential oils were obtained by hydrodistillation, yielding between 0.57 and 2.46% (v/w). On the basis of the 13 main compounds determined by GC-FID-MS, representing the 87.2 and 95.3% of the total identified, four chemotypes were determined: carvacrol, thymol, cis and trans-dihydrocarvone and linalool-geraniol. The co-occurrence of different chemotypes in a same population indicates that the sample collection must be carefully done with the aid of an in situ olfactory testing of the plants, since no morphological differences at first sight were observed among them. The results showed in this study suggest that the pattern of variations for this species exists throughout its natural distribution area.Se colectaron 19 muestras de partes aéreas en floración de Acantholippia seriphioides (Verbenaceae) de tres provincias de la región de Cuyo de la Argentina. Los aceites esenciales fueron obtenidos por hidrodestilación, arrojando rendimientos entre 0.57 y 2.46% (v/p). A partir de la determinación por GC-FID-MS de los 13 compuestos principales, que representaban entre el 87.2 y 95.3% del total de los identificados, fueron determinados cuatro quimiotipos: carvacrol, timol, cis y trans-dihidrocarvona, y linalol-geraniol. La co-ocurrencia de diferentes quimiotipos en una misma población indica que la colecta debe ser realizada con la ayuda de un examen olfatorio in situ de la planta, ya que, a primera vista no se observan diferencias morfológicas entre ellas. Los resultados sugieren que el patrón de variación para esta especie existe en toda su área de distribución natural.Fil: Van Baren, Catalina Maria. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Farmacología. Cátedra de Farmacognosia; ArgentinaFil: Elechosa, Miguel Angel. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Recursos Biológicos; ArgentinaFil: Di Leo Lira, Paola. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Farmacología. Cátedra de Farmacognosia; ArgentinaFil: Retta, Daiana S. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Farmacología. Cátedra de Farmacognosia; ArgentinaFil: Juarez, Miguel Angel. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Recursos Biológicos; ArgentinaFil: Martinez, Alejandro. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Recursos Biológicos; ArgentinaFil: Molina, Ana Maria. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Recursos Biológicos; ArgentinaFil: Bandoni, Arnaldo L. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Farmacología. Cátedra de Farmacognosia; Argentin

Frequency-Time Domain Analysis of Electrochemical Noise of Passivated AM350 Stainless Steel for Aeronautical Applications

Precipitation-hardening stainless steel is frequently utilized in a variety of aerospace applications. While the latter steel is employed in applications demanding great strength and corrosion resistance, the former steel offers good corrosion resistance with moderate strength. In this work, the corrosion behavior of AM 350 stainless steel exposed to solutions containing 5% NaCl and 1% H2SO4 after being passivated in nitric acid and citric acid solution for 50 min each at 49 and 70°C is examined. AM 350 stainless steel is precipitation hardening stainless steel, widely used in various aerospace applications. The former steel exhibits excellent corrosion resistance with moderate strength, whereas the latter is used for applications requiring high strength and corrosion resistance. In this study, AM 350 stainless steel corrosion behavior passivated in a) citric acid and b) nitric acid solutions for 50 min at 49 and 70 °C, and subsequently exposed in 5 wt. % NaCl and 1 wt. % H2SO4 solutions are investigated. The electrochemical technique used was electrochemical noise (EN), based on the ASTMG199 standards. Two data analysis techniques were employed for EN: the time-frequency domain (wavelets transform) and the power spectral density (PSD). The results showed a better behavior against corrosion of samples passivated in nitric acid in citric acid. Also, in NaCl electrolyte, the uniform process is the predominant behavior

Corrosion Behavior of Titanium and Titanium Alloys in Ringer ́sSolution

Titanium and its alloys are employed as medical materials because of their low Young's modulus, excellent biocompatibility, and superior corrosion resistance. This work aimed to characterize the electrochemical behavior of titanium Ti-CP2 and alloys Ti-6Al-2Sn-4Zr-2Mo, and Ti-6Al-4V. Ti and Ti-alloys were exposed to Ringer ́ssolution at room temperature. The electrochemical characterization was made by cyclic potentiodynamic polarization (CPP) and electrochemical noise technique (EN). Two different methods filtered EN signal, the polynomial method and the potential spectral density (PSD). Also, the Wavelets method, where energy dispersion plots were obtained. Results indicated thatTi-6Al-2Sn-4Zr-2Mo presented less dissolution when exposed in Ringer analysis by ψ0. The wavelet method showed a diffusion process occurring on the surface

Un perfil sísmico de reflexión somera en el complejo de la caldera La Reforma, Baja California Sur, México

https://geos.cicese.mx/index.php/geos/issue/view/1

Susceptibility to Pitting Corrosion of Ti-CP2, Ti-6Al-2Sn-4Zr-2Mo, and Ti-6Al-4V Alloys for Aeronautical Applications

Titanium alloys are used in different industries like biomedical, aerospace, aeronautic, chemical, and naval. Those industries have high requirements with few damage tolerances. Therefore, they are necessary to use materials that present fatigue, mechanical, and corrosion resistance. Although Ti-alloys are material with high performance, they are exposed to corrosion in marine and industrial environments. This research shows the corrosion behavior of three titanium alloys, specifically Ti CP2, Ti-6Al-2Sn-4Zr-2Mo, and Ti-6Al-4V. Alloys were exposed on two electrolytes to a 3.5 wt % H2SO4 and NaCl solutions at room temperature using cyclic potentiodynamic polarization (CPP) and electrochemical noise (EN) according to ASTM G61 and ASTM G199 standards. CPP technique was employed to obtain electrochemical parameters as the passivation range (PR), corrosion type, passive layer persistence, corrosion potential (Ecorr), and corrosion rate. EN was analyzed by power spectral density (PSD) in voltage. Results obtained revealed pseudopassivation in CPP and PSD exposed on NaCl for Ti-6Al-2Sn-4Zr-2Mo, indicating instability and corrosion rate lower. However, Ti-6Al-4V presented the highest corrosion rate in both electrolytes. Ti-6Al-2Sn-4Zr-2Mo revealed pseudopassivation in CPP and PSD in NaCl, indicating a passive layer unstable. However, the corrosion rate was lower in both solutions

Essential oil chemotypes of Aloysia citrodora (Verbenaceae) in Northwestern Argentina

Chemical biodiversity of essential oils of natural populations of Aloysia citrodora Palau (“lemon verbena”, “cedrón”) in Northwestern Argentina was assessed by collecting in the same sites through different years. A total of 36 samples were collected in the Provinces of Salta (El Maray, La Paya, El Sunchal, El Alisal, Chorrillos), Jujuy (Chilcayo, San Roque), Catamarca (Mutquin, Colana) and Tucumán (Amaicha del Valle) in Argentina. Essential oils were obtained by hydrodistillation (Clevenger) of naturally air-dried plant material. Yields ranged from 0.16% to 1.93% (v/w), being the highest those of the collections of Mutquin. More than 65 compounds were identified by CG-FID-MS. Only 19 of these constituents, accounting from 77.3 to 98.9% of the total oil, present in more than 4.0% in at least one sample, were considered as variables for statistical analysis. Agglomerative Hierarchical Cluster analysis was conducted, showing at 65% of similarity, five groups. This grouping was in direct accordance to the biosynthetic pathways of main compounds (chemotypes). In the two sites of Jujuy, 21 collections evidenced four different chemotypes, named after the dominant component as follows: thujones, citronellal, carvone, and citral (neral + geranial). In the populations of Salta and Catamarca, linalool appeared as a new different chemotype. Though cedron is considered as a citral-bearing plant, curiously, in the 36 samples collected in the NW of Argentina, only two samples contained citral as main constituent. On the other hand, a dominance of citronellal and thujones compositions were found in the bulk of the samples collected, while others had very high content of linalool or carvone and its derivatives. Northwestern Argentina has repeatedly been mentioned as the center of biodiversity of this species. The new evidences found on the chemical biodiversity of essential oils of Aloysia citrodora in natural populations in this region, reinforce firmly this idea.Instituto de Recursos BiológicosFil: Elechosa, Miguel Angel. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Recursos Biológicos; ArgentinaFil: Di Leo Lira, Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Metabolismo del Fármaco. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Metabolismo del Fármaco; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Farmacología. Cátedra de Farmacognosia; ArgentinaFil: Juarez, Miguel Angel. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Recursos Biológicos; ArgentinaFil: Viturro, Carmen Ines. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Jujuy. Facultad de Ingeniería; ArgentinaFil: Heit, Cecilia I.. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Jujuy. Facultad de Ingeniería; ArgentinaFil: Molina, Ana C. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Jujuy. Facultad de Ingeniería; ArgentinaFil: Martinez, Alejandro. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Recursos Biológicos; ArgentinaFil: López, Simón. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Salta; ArgentinaFil: Molina, Ana Maria. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Recursos Biológicos; ArgentinaFil: van Baren, Catalina María. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Metabolismo del Fármaco. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Metabolismo del Fármaco; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Farmacología. Cátedra de Farmacognosia; ArgentinaFil: Bandoni, Arnaldo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Metabolismo del Fármaco. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Metabolismo del Fármaco; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Farmacología. Cátedra de Farmacognosia; Argentin

Corrosion Behavior of Titanium Alloys (Ti CP2, Ti-6Al-2Sn-4Zr-2Mo, Ti-6Al-4V and Ti Beta-C) with Anodized and Exposed in NaCl and H₂SO₄ Solutions

Nowadays, different industries, such as the aerospace and biomedical industries, prefer using Ti alloys due to their excellent anti-corrosion properties and ability to generate a TiO2 oxide layer; this induces the use of anodization to increase the useful life of components. The aim of this work is to characterize the electrochemical effect of anodizing treatment on titanium alloys (Ti CP2, Ti-6Al-2Sn-4Zr-2Mo, Ti-6Al-4V, and Ti Beta-C) in NaOH and KOH at 1 M, applying a current density of 0.0025 A/cm2. The electrochemical techniques employed were electrochemical noise (EN) and electrochemical impedance spectroscopy (EIS), supported by ASTM G199 and ASTM G106 in electrolytes of NaCl and H2SO4 at 3.5 wt. % as a simulation of marine and industrial atmospheres. Also, the anodized transversal section and surface morphology were characterized by a scanning electron microscope (SEM). The results of both electrochemical techniques indicated that Ti-6Al-2Sn-4Zr-2Mo anodized in NaOH presented the best properties against corrosion, and the thickness of the oxide was the biggest