The stress corrosion cracking behaviour of heat-treated Al–Zn–Mg–Cu Alloy in Modified salt Spray Fog Testing

The stress corrosion cracking behaviour of 7075 (Al–Zn–Mg–Cu) alloy have been studied in a salt spray fog chamber with two vapourised aqueous solutions (0 and 5% NaCl). The paper analyses the stress corrosion resistance of 7075 aluminium alloy with several precipitation-ageing heat treatments. The results are compared with that obtained in 3.5% NaCl aqueous solution at 20 °C. The salt spray fog testing has permitted a good evaluation of SCC susceptibility in 7075 alloy. All temper conditions studied were susceptible to SCC in the different environments tested. 7075-T6 temper was the most susceptible, while in all the cases studied 7075-T73 temper was the least susceptible. Compared to 7075-T6, 7075-RRA temper improved the resistance against the SCC process, but the mechanical properties obtained were lower

High-temperature mechanical properties of aluminium alloys reinforced with titanium diboride (TiB2) particles

The physical and mechanical properties of metal matrix composites were improved by the addition of reinforcements. The mechanical properties of particulate-reinforced metal-matrix composites based on aluminium alloys (6061 and 7015) at high temperatures were studied. Titanium diboride (TiB2) particles were used as the reinforcement. All the composites were produced by hot extrusion. The tensile properties and fracture characteristics of these materials were investigated at room temperature and at high temperatures to determine their ultimate strength and strain to failure. The fracture surface was analysed by scanning electron microscopy. TiB2 particles provide high stability of the aluminium alloys (6061 and 7015) in the fabrication process. An improvement in the mechanical behaviour was achieved by adding TiB2 particles as reinforcement in both the aluminium alloys. Adding TiB2 particles reduces the ductility of the aluminium alloys but does not change the microscopic mode of failure, and the fracture surface exhibits a ductile appearance with dimples formed by coalescence

Comportamiento a fatiga de uniones a solape simple de acero prepintado y galvanizado con adhesivo silano modificado

(SPA) Se ha estudiado el comportamiento a fatiga de uniones adhesivas estructurales a solape simple. Los elementos estructurales fabricados en acero recubierto (galvanizado o pintado) sujetos a fluctuaciones de tensiones y deformaciones pueden fallar después de un número elevado de ciclos. El adhesivo silano modificado (MS) ha sido utilizado para la evaluación de la resistencia mecánica y a la fatiga de uniones de chapa delgada de acero protegido. El objetivo de este trabajo es analizar la influencia del recubrimiento en el comportamiento a fatiga de las uniones adhesivas con silano modificado. Las mejores propiedades se obtuvieron para el acero galvanizado con fallo cohesivo. Los resultados muestran que la compatibilidad química del adhesivo y la capa galvanizada mejoran la adhesión de la unión y la resistencia frente a cargas estáticas y dinámicas. Se ha obtenido el límite de fatiga para las uniones estudiadas. (ENG) The fatigue behaviour of single overlap of structural bonded joints was evaluated. Structural components made of thin coated steel (galvanised or painted) subjected to fluctuating stresses and strains may failure after a sufficient number of fluctuations. The modified silane adhesive (MS) has been used to evaluate the static and fatigue resistance of thin coated steel sheet joints. The aim of this paper is analyse the influence of coated on the fatigue behaviour of modified silane bonded joints. The best properties were obtained for galvanised steel with cohesive failure. The results show that chemical compatibility of adhesive and galvanized layer improve adhesion of joints and the mechanical resistance against static and dynamic loads. The fatigue limited has been obtained for joints studied

De sacra scriptura: la palabra de Dios, escuela de oración*

A fundamental dimension of the Word of God is discovering it as a real «School of Prayer» because behind each biblical expression one may found the «silent voice» of a loving father, eager to create again his children to build up communities as a big family. The author unfolds his arguments studying thoroughly the psalm 150, which closes partially the praises in Israel, and leaves an open space to create our owwn psalms as far as our daily life goes on.Una de las dimensiones fundamentales de la Palabra de Dios consiste en descubrirla como una verdadera «Escuela de oración»; pues detrás de cada expresión bíblica, se encuentra la «voz silenciosa» de un papá amoroso, quien busca recrear cada día a sus hijos e hijas para hacer de las comunidades una gran familia. El autor desarrolla estos argumentos estudiando en forma detenida el Salmo 150, el cual entrecierra la puerta de las «Alabanzas» en Israel, pero a la vez deja abierto un espacio para forjar nuestros propios salmos en el trasegar de la historia cotidiana

Influencia de los fertilizantes y el drenaje en la calidad del tabaco (N. yabacum L.).

Tabaco-Nicotiana tabacum L.Maestría en CienciasMaestrí

Valoración de la respuesta inmunológica linfocitaria en pacientes con bronquiolitis aguda. Medición de patrones de expresión génica, quimioquinas y receptores de quimioquinas

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Medicina, Departamento de Pediatría. Fecha de lectura: 07-06-201