WorldWideScience

Sample records for calmado al aluminio

  1. Revisión de los estudios sobre exposición al aluminio y enfermedad de Alzheimer

    Directory of Open Access Journals (Sweden)

    Suay Llopis Loreto

    2002-01-01

    Full Text Available Se ha llevado a cabo una revisión bibliográfica de los estudios epidemiológicos que han evaluado el papel del aluminio como factor de riesgo para el desarrollo de la enfermedad de Alzheimer. Se realizó una búsqueda bibliográfica en la base de datos MedLine combinando los términos del Thesaurus "Aluminum" y "Alzheimer´s disease". En la mayor parte de los estudios revisados se ha examinado la exposición al metal a través del agua de bebida. Los estudios que sugieren que existe una asociación entre el aluminio y la enfermedad presentan riesgos relativos de alrededor de 2 para poblaciones con exposiciones a concentraciones de Al en el agua mayores de 0,1 mg/l. Las exposiciones al metal a través de otras vías (alimentación, medicamentos y exposición laboral han sido poco estudiadas. Estos estudios epidemiológicos presentan limitaciones metodológicas y sus resultados no son consistentes por lo que los resultados disponibles hasta el momento no permiten establecer, de manera clara, que exista una asociación entre la exposición al metal y la etiología de la enfermedad de Alzheimer. No obstante, tampoco es posible descartar un papel tóxico del aluminio sobre la salud, por lo que su exposición debería ser controlada y reducida en lo posible.

  2. Efecto de la precipitación de nitruros de aluminio en la recristalización de aceros de bajo carbono recocidos convencionalmente

    Directory of Open Access Journals (Sweden)

    Monsalve, A.

    2005-10-01

    Full Text Available An important feature of aluminium killed steels is the strong influence that aluminium nitride precipitates produce in both the mechanical properties and the final microstructural characteristics of the steel. This influence is related to the different stages of the fabrication process. This paper deals with a study of the effects of aluminium nitrides on the kinetics of recrystallisation. Different heat treatments were carried out, in one case to dissolve AIN, and in the other in order to precipitate AIN. These steels were subjected to cold rolling, followed by a batch annealing process. The recrystallised fraction was measured, thus obtaining the kinetic curves. The activation energy for recrystallisation was computed in each case. The results showed that AIN precipitation during recrystallisation produces a delay in recrystallisation kinetics through a change in the activation energy value.

    Los aceros calmados con aluminio presentan como característica importante, la gran influencia que ejercen los nitruros de aluminio en las propiedades mecánicas y características microestructurales finales. Esta influencia está, a su vez, relacionada con cada una de la etapas del proceso de fabricación. En el presente trabajo se ha abordado el estudio del efecto de los nitruros de aluminio sobre la cinética de recristalización. Para ello, se han llevado a cabo diversos tipos de tratamientos térmicos, con el objeto de disolver todo el AIN y, en el otro caso, de precipitar todo el AIN. A continuación, los aceros estudiados se deformaron en frío y se les realizó un recocido convencional. Se midió la fracción recristalizada evaluando la energía de activación para la recristalización. Los resultados mostraron que la precipitación de AIN durante la recristalización produce un retraso en la cinética de recristalización, a través del cambio en el valor de la energía de activación

  3. Corrosión por picaduras del aluminio y de la aleación Al-6201 en soluciones de NaCl

    Directory of Open Access Journals (Sweden)

    Vera, R.

    1998-06-01

    Full Text Available The susceptibility of pure aluminum and aluminum 6201 alloy to pitting was investigated in sodium chloride solutions through determination of the corrosion, repassivation and pitting potentials. Potentiodynamic polarization including scratching techniques were employed being also determined the type and relative amount of corrosion damage to the metals. The morphology of the attack was determined using scanning electron microscopy (SEM. The results showed a similar performance for aluminum 6201 alloy and aluminum. It was also observed that an increase in chloride concentration resulted in a decrease in the corrosion, pitting and repassivation potentials of both materials.

    Gran cantidad de estudios realizados sobre el comportamiento del aluminio y sus aleaciones han demostrado su excelente resistencia a diversos medios corrosivos. Sin embargo, en las líneas de transmisión de energía eléctrica de aluminio o de la aleación comercial Al-6201, instaladas en las costas de Valparaíso, Chile, se detectaron fallos del material, consistentes en picaduras profundas y roturas. En este estudio se evalúa la corrosión por picaduras sufrida por el aluminio y la aleación Al-6201, utilizando soluciones de diferentes concentraciones de NaCl que es el principal agente agresivo en ambientes marinos. Se determinaron los potenciales de corrosión (Ec, de repasivación (Er y de picado (Ep, mediante el empleo de curvas de polarización potenciodinámicas y técnica de raspado. La morfología del ataque se determinó mediante microscopía electrónica de barrido. Los resultados mostraron un comportamiento similar entre el aluminio y la aleación 6201. También se observó que el aumento en la concentración de cloruro conlleva una disminución en los potenciales de corrosión, de picaduras y de repasivación en ambos materiales.

  4. Reciclaje de aluminio: oportunidades de desarrollo en Bogotá (Colombia

    Directory of Open Access Journals (Sweden)

    Federico Millan Delgado

    2015-07-01

    Full Text Available La resistencia a la corrosión y ligereza que caracterizan al aluminio permiten que este metal y sus aleaciones sean sustitutos de materiales como el acero en diversas aplicaciones industriales como: construcción, autopartes, empaques, maquinaría y aeronáutica. En consecuencia, la demanda de aluminio se ha incrementado, así como la búsqueda de minas de bauxita, mineral a partir del cual se obtiene este metal. La transformación de la bauxita en aluminio se realiza mediante la explotación y extracción del mineral que posteriormente es sometido a procesos químicos de Bayer y de electrólisis, los cuales generan emisiones nocivas para el medio ambiente y demandan un alto consumo de energía. Ante la necesidad de reducir los costos de producción del proceso y su impacto ambiental, una alternativa como fuente de materia prima es el reciclaje de aluminio, como lo indican investigaciones sobre el aprovechamiento de materiales en países como Brasil y Estados Unidos que han demostrado la viabilidad de obtener aluminio a partir de residuos metálicos. Lo anterior plantea un interrogante sobre los avances en esta materia en Bogotá, una ciudad con una cadena de reciclaje informal de numerosos eslabones y con escasa regulación que ha generado pocos logros en comparación con otras capitales del mundo.

  5. Un hidrogel de hidróxido de aluminio para eliminar el arsénico del agua

    OpenAIRE

    Luján Juan Carlos

    2001-01-01

    Objetivos. Describir la síntesis y los resultados preliminares de la aplicación de un hidrogel de hidróxido de aluminio que, agregado directamente al agua, pueda lograr la eliminación total del arsénico, cualquiera que sea la naturaleza del agua y el estado de oxidación del metaloide. Métodos. Las materias primas utilizadas para obtener el hidrogel de hidróxido de aluminio fueron: sulfato de aluminio hidratado (que se utiliza para potabilizar aguas), hipoclorito de calcio en polvo, hidróxido ...

  6. CLARIFICACIÓN DE AGUAS USANDO COAGULANTES POLIMERIZADOS: CASO DEL HIDROXICLORURO DE ALUMINIO

    Directory of Open Access Journals (Sweden)

    JUAN MIGUEL COGOLLO FLÓREZ

    2011-01-01

    Full Text Available En este artículo se realiza un estudio del proceso de clarificación en sistemas de tratamiento de aguas industriales usando un coagulante inorgánico polimerizado (hidroxicloruro de aluminio. Inicialmente, se establecen los elementos conceptuales más importantes de las etapas del proceso de clarificación (coagulación, floculación y sedimentación. Luego, se señalan los principales coagulantes convencionales utilizados en el tratamiento de aguas y se abordan los policloruros de aluminio (PAC´s como integrantes de una nueva generación de coagulantes alternativos cuyo uso se ha incrementado en las últimas décadas dado su mejor desempeño respecto a los coagulantes convencionales; se especifican los aspectos técnicos y operativos que se deben considerar al momento de implementar un proceso de clarificación de aguas usando un PAC como coagulante. Finalmente, se presentan datos comparativos de condiciones operacionales reales de un proceso de clarificación de aguas, producto de un trabajo previo, donde se remplazó un coagulante convencional (sulfato de aluminio por hidroxicloruro de aluminio, donde se corrobora el mejor desempeño del proceso luego del remplazo.

  7. Aleaciones de aluminio amorfas y nanoestructuradas

    Directory of Open Access Journals (Sweden)

    García-Escorial, A.

    1998-05-01

    Full Text Available The work carried out in CENIM on amorphous and nanostructured aluminium alloys is described. Results about Al-LTM-ETM, Al-Fe-Nb and Al-Cu-Zr, and Al-LTM-RE, Al-Fe-Nd (LTM = Late Transition Metal, ETM = Early Transition Metal y RE = Rare Earth alloys obtained by rapid solidification, inert gas atomization and melt-spinning, as well as mechanical alloying are presented.

    En este trabajo se recoge la labor desarrollada en el CENIM en aleaciones de base aluminio amorfas y nanoestructuradas. Se presentan los resultados obtenidos hasta ahora en el estudio de aleaciones Al-LTM-ETM, Al-Fe-Nb y Al-Cu-Zr, y Al-LTM-RE, Al-Fe-Nd (LTM = Late Transition Metal, ETM = Early Transition Metal y RE = Rare Earth, procesadas por solidificación rápida, mediante atomización por gas inerte y temple ultrarrápido sobre rueda, así como por aleado mecánico en molino de bolas de alta energía.

  8. Aluminio pulvimetalúrgico: desarrollo y mejora de sus aleaciones y materiales compuestos

    Directory of Open Access Journals (Sweden)

    Ruiz-Navas, E. M.

    2008-06-01

    Full Text Available Powder metallurgy components demand is increasing in the last few years mainly due to the necessity of products assigned to automotive and aerospace industries, which has allow an important development of aluminium alloys and composites (AMCs. Consolidation of aluminium alloys by sintering present a main problem: the oxide layer that cover aluminium particles. Several alternatives are studied in this work as solution to the oxide layer problem during the sintering of series 2xxx aluminium alloys. One of these solutions is related to the addition of tin traces, and the other is the addition of a second alloy. Moreover, aluminium metal matrix composites are characterized by excellent properties as combination of properties which comes from the matrix and from the reinforcement. The last part of this study is focused to the analysis of one aluminium matrix composite as the influence of several quantities of reinforcement.

    El auge en la demanda de componentes pulvimetalúrgicos destinados principalmente al sector automovilístico y aeroespacial ha permitido un fuerte desarrollo tanto de aleaciones como de MMCs base aluminio (AMCs. El principal problema a la hora de consolidar estos materiales vía pulvimetalúrgica es la capa de óxido que recubre a las partículas de aluminio. En este trabajo se presentan varias alternativas como solución a este problema, aplicadas a la consolidación de aleaciones de aluminio pertenecientes a la serie 2xxx, entre ellas, la adición de trazas de estaño y la adición de una aleación Al-Si. En cuanto a los materiales compuestos de matriz de aluminio, se caracterizan por presentar propiedades únicas como combinación de las propiedades individuales que caracterizan tanto a la matriz como al refuerzo. En la última parte de este trabajo se estudia la consolidación de un material compuesto así como la influencia de las distintas cantidades de refuerzo.

  9. Recubrimientos vítreos de cerio para la protección activa de aleaciones de aluminio

    OpenAIRE

    Yhasmin Reyes; Alicia Durán; Yolanda Castro

    2015-01-01

    Las buenas propiedades mecánicas, alta conductividad eléctrica y térmica y bajo coste de mecanización del aluminio y sus aleaciones, permiten su uso en un amplio campo de aplicaciones. Sin embargo, al exponerse a ambientes agresivos, el aluminio sufre corrosión localizada. En este trabajo, se estudia la preparación de recubrimientos vítreos de óxido de cerio, sintetizados a partir de nitrato de cerio y diversos complejantes para mejorar la resistencia a la corrosión de las aleaciones AA2024 y...

  10. El aluminio en el suelo y algunas estrategias de manejo

    Directory of Open Access Journals (Sweden)

    Fabio Emilio Forero-Ulloa

    2011-02-01

    Full Text Available El  suelo  está  compuesto por diversos  elementos entre  los que  se destaca el aluminio, como un metal que, en condiciones  normales,    no  afecta  el desarrollo de las plantas,  pero en suelos ácidos  es un factor limitante en el crecimiento de la mayoría de especies vegetales,  con una afectación cercana al 50% del área sembrada  en el ámbito mundial. En Colombia  cerca del  85% de  los  suelos  son ácidos,  por lo cual es  necesario buscar estrategias de manejo  y  permitir  que  estos  suelos  sean adecuados para  obtener producción  agrícola, máxime  si  en nuestro  territorio existen diversos tipos  de  suelos,  como  consecuencia  de  los diferentes materiales parentales que,  al final, son necesarios    tener en cuenta para  implementar el manejo estratégico del aluminio.

  11. Recubrimientos de aluminio-silicio realizados por deposición química de vapor en lecho fluidizado sobre el acero inoxidable AISI 316

    Directory of Open Access Journals (Sweden)

    José Luddey Marulanda Arevalo

    2013-12-01

    Full Text Available Los recubrimientos de aluminio-silicio fueron depositados sobre el acero inoxidable AISI 316 mediante deposición química de vapor en lecho fluidizado (CVD-FBR, en el rango de temperaturas de 540 a 560 ºC, utilizando un lecho formado por 2,5 g de silicio y 7,5 g de aluminio en polvo, y 90 g de lecho inerte (Alúmina, el cual se hizo fluidizar con Ar. Como gases activadores se usó una mezcla de HCl/H2, en relaciones de 1/10 a 1/16. Además, se varió el tiempo de deposición de los recubrimientos de 45 minutos a 1.5 horas, con una relación en volumen de 50% de gases activos y 50% de gases neutros. Se realizó una simulación termodinámica con la ayuda del programa informático Thermocalc, para obtener información de la posible composición y cantidad de material depositado, para las condiciones seleccionadas. En los recubrimientos se encuentran FeAl2Si, Fe2Al5 y FeAl2. Los recubrimientos aluminio-silicio fueron tratados térmicamente, para mejorar sus propiedades mecánicas y su comportamiento frente a la oxidación, por la interdifusión de los elementos de aleación, ya que el tratamiento térmico hace que el aluminio difunda hacia el substrato, y el hierro difunda hacia la superficie del recubrimiento, logrando la transformación de los compuestos anteriores en FeAl, Al2FeSi, Cr3Si, AlCrFe y AlFeNi.

  12. Alternativas al cromo en la industria del acabado superficial del aluminio. Tratamientos superficiales de bajo impacto ambiental

    Directory of Open Access Journals (Sweden)

    Aballe Villero, Álvaro

    2001-02-01

    Full Text Available Chromates are one of the most commonly used compounds in anticorrosive protection systems because of its excellent rate efficiency/cost. In the case of aluminium alloys, these compounds are employed as inhibitors as well as in the anticorrosive pretreatments to develop protective films. However, chromates are highly toxic and its use involves a high risk for health and environment. Consequently, in the last years intensive efforts have been achieved in the surface treatment industry to find ecological alternatives to this kind of compounds. In this work, the main alternatives proposed in literature to substitute chromates in the surface treatments of aluminium alloys are reviewed. To begin with, the role of chromates in these systems and their environmental consequences has been briefly reviewed.

    Los cromatos son unas de las sustancias más comúnmente empleadas en los sistemas de protección frente a la corrosión de aleaciones metálicas, debido a su excelente relación eficacia/coste. En el caso de las aleaciones de aluminio, estos compuestos se aplican tanto como inhibidores, incorporados al medio agresivo, como en pretratamientos anticorrosivos para la formación de películas protectoras. Sin embargo, los cromatos son altamente tóxicos y su uso conlleva un elevado riesgo para la salud laboral y el medio ambiente. Por esta razón, dentro de la industria del acabado superficial, en los últimos tiempos, se ha venido realizando un intenso esfuerzo para buscar alternativas ecológicamente aceptables a este tipo de compuestos. En este trabajo se revisan las principales alternativas planteadas en la bibliografía para sustituir a los cromatos en los tratamientos superficiales de las aleaciones de aluminio. Como punto de partida, se ha llevado a cabo un breve repaso al papel que juegan los cromatos en los sistemas de protección frente a la corrosión y las implicaciones medioambientales que conlleva su uso.

  13. ESTRATEGIAS DE LA REUTILIZACIÓN DEL ALUMINIO PARA EL EMBELLECIMIENTO DEL HOGAR

    Directory of Open Access Journals (Sweden)

    Zoraida Contreras

    2013-06-01

    Full Text Available El proyecto ambiental se desarrolló y se presentó de manera interdisciplinaria en el encuentro de Semilleros FESC 2012. La motivación a los estudiantes de Procesos Aduaneros para que sean conscientes del impacto ambiental que se genera en la región y a nivel internacional con la reutilización del aluminio; de ahí la importancia de involucrar el Semillero de Investigación para realizar un estudio y reflejar la problemática. Con esta investigación los estudiantes proponen una solución o dan inicio a un cambio en el pensamiento del sector, siendo desde su trabajo forjadores de una actitud más amigable frente al medio ambiente, generando propuestas, alternativas e innovaciones con los residuos de aluminio.

  14. Fenómenos de corrosión galvánica en las uniones aluminio y acero

    OpenAIRE

    Domínguez Parra, Alberto

    2009-01-01

    La corrosión es un proceso de degradación de un material al interactuar con el ambiente que le rodea. El presente proyecto trata de la corrosión galvánica de aceros y fundiciones, en contacto con aleaciones de aluminio. Su experimentación se ha realizado con acero AE 275 B, y fundición EN-GS 400 12. Se utilizó lingote de aluminio A356 obtenido por colada por gravedad, y dos tipos de muestras, con y sin tratamiento térmico T6, de A 356 producidas por el procedimiento de sub-liquidus casting...

  15. Corrosión filiforme del aluminio lacado

    Directory of Open Access Journals (Sweden)

    Bautista, A.

    1996-10-01

    Full Text Available Filiform corrosion is a type of localized corrosion which can affect some painted metals (usually Steel, aluminium and magnesium. It often occurs in specimens exposed to marine environments, and produces protective coating damage and thread-like metal base attack. In the paper a brief review of filiform corrosion on coated aluminium is shown. The survey analyses the role which some factors play in the initiation of the filaments, summarizes their growing mechanism and shows the main proposed solutions to this problem.

    La corrosión filiforme es un tipo de corrosión localizada que puede afectar a algunos metales pintados (normalmente acero, aluminio y magnesio. Suele ocurrir en piezas expuestas a atmósferas marinas, y da lugar al deterioro del recubrimiento protector y a un ataque en forma de filamentos del metal base. En este trabajo se presenta una breve revisión bibliográfica sobre la corrosión filiforme en el aluminio lacado. Igualmente, se analiza el papel que juegan diversos factores en la aparición de los filamentos de corrosión, se resume el mecanismo por el que progresan y se recogen las principales soluciones propuestas para este problema.

  16. Recuperación del cromo y aluminio del licor de desecho (wl en forma de sales dobles

    Directory of Open Access Journals (Sweden)

    Pedro R. Bassas-Noa

    2006-03-01

    Full Text Available El licor WL es un residual de la industria del níquel agresivo al medio ambiente por su acidez que contiene elementos metálicos de gran valor. Se propone un tratamiento para la separación con  hidróxido de amonio y la recuperación de la mayor cantidad de cromo y aluminio contenidos en el mismo. Se logra precipitar una mezcla de hidróxidos de aluminio que tratada con ácido sulfúrico permite obtener, por cristalización, la sal sulfato de aluminio y amonio dodecahidratada. Posteriomente se cristaliza la sal sulfato doble de cromo y amonio dodecahidratado. Se demuestra que el sulfato doble de cromo y amonio dodecahidratado y el sólido separado presentan características químicas que hacen posible su aplicación en la industria textil y de cerámica, entre otras. El esquema aplicado permite la recuperación de valores metálicos y la disminución del alto poder contaminante del licor de desecho WL.

  17. Reactividad entre whiskers de α-SiC y aluminio durante el procesado por vía líquida de materiales compuestos de matriz metálica

    Directory of Open Access Journals (Sweden)

    Ureña, A.

    1999-06-01

    Full Text Available The reactivity between α-SiC whiskers and an aluminium alloy (Al-Cu-Mg, both present in a metal matrix composite, has been studied when such matrix is in molten state. Using mainly transmission electron microscopy (TEM and electron microdiffraction (ED, the nature and morphology of the reaction products generated at the α-SiC/aluminium interface, when this last melts under different condition which simulate casting and welding procedures for metal matrix composites, have been characterised. Both the formation of Al4C3 aggregates with platelet morphology generated by dissolution-reaction mechanisms, and aciculate crystals of the same carbide form by complete dissolution of the α-SiC whiskers and later Al4C3 precipitation into the molten aluminium. Ternary Al-Si carbides with high chemical stability have been also identified by TEMED (β-Al4SiC4, being its formation related with higher energetic conditions than for the Al4C3.

    Se realiza un estudio de la reactividad entre whiskers de α-SiC y una aleación de aluminio en estado líquido (Al-Cu-Mg, que forman parte de un material compuesto de matriz metálica. Empleando fundamentalmente técnicas de microscopía electrónica de barrido (MEB y de transmisión (MET, junto con difracción de electrones (DE, se ha caracterizado la naturaleza y morfología de los productos de reacción que se generan en la intercara α-SiC/aluminio, cuando éste funde en diferentes condiciones que simulan procesos de fabricación y soldadura del material compuesto. Se ha observado tanto la formación de agregados de Al4C3 con morfología tabular producidos por mecanismos de disolución-reacción de los whiskers, como de cristales aciculares del mismo tipo de carburo formados por disolución total de α-SiC y precipitación en el aluminio fundido. Se ha determinado también que, en condiciones suficientemente energéticas, pueden llegar a formarse carburos ternarios de aluminio y silicio (β-Al4SiC4 que

  18. Estudio del comportamiento térmico del polvo de aluminio estabilizado con el yeso

    Directory of Open Access Journals (Sweden)

    López-Delgado, A.

    2005-12-01

    Full Text Available The aluminium dust is a hazardous waste from the secondary aluminium remelting industry. A stabilization/solidification process was developed at CENIM with the aim of decreasing its reactivity. Gypsum was used as a binder material. This work summarizes the study of the thermal behavior of the aluminium dust stabilized with gypsum, in order to establish the influence of the residue in the reactions of hydration/dehydration of the gypsum during the hardening process, namely: partial dehydration of calcium sulphate dihydrate, dehydration of calcium sulphate hemi-hydrate, dehydration of aluminium hydroxide and anhydrite soluble/anhydrite insoluble transformation. The activation energy associated to all those reactions was determined by Differential Scanning Calorimetry.

    El polvo de aluminio (pAl es un residuo peligroso procedente de la metalurgia secundaría del aluminio. Con objeto de reducir la reactividad del mismo, en el CENIM se ha desarrollado un proceso de estabilización/solidificación mediante su fraguado con yeso. En este trabajo se presenta el estudio del comportamiento térmico del pAl estabilizado con el yeso, con el fin de establecer la influencia del residuo en las reacciones de hidratación/deshidratación del yeso durante el proceso del fraguado, a saber: deshidratación parcial del sulfato cálcico dihidrato, deshidratación del hemihidrato, deshidratación del hidróxido de aluminio y transformación de anhidrita soluble en anhidrita insoluble. Asimismo se ha estudiado la cinética asociada a cada una de las reacciones anteriormente mencionadas mediante Calorimetría Diferencial de Barrido.

  19. Comportamiento del aluminio desnudo y anodizado en atmósferas con grados de contaminación muy diferentes

    Directory of Open Access Journals (Sweden)

    Bautista, A.

    1998-05-01

    Full Text Available In the present research, the responses of unprotected and anodized aluminium specimens are compared after they have been exposed to 12 different atmospheres. The significance of the anodizing and the sealing on the atmospheric corrosion behaviour is analysed. The results show that the anodizing and sealing of aluminium exclude the risk of pitting corrosion in marine atmospheres and that the oxide thickness is not determining, at least during the first year of exposure.

    En la presente investigación, comparando las respuestas de muestras de aluminio desnudas y anodizadas, expuestas a 12 atmósferas diferentes, se analiza la repercusión del anodizado y sellado del aluminio en el comportamiento frente a la corrosión atmosférica. Se demuestra que la anodización y sellado del aluminio elimina el riesgo de corrosión por picaduras que afecta a estos materiales en atmósferas marinas, sin que el espesor del recubrimiento resulte determinante, al menos, en el primer año de exposición.

  20. EFECTO DEL ULTRASONIDO EN LA SÍNTESIS DE ARCILLA PILARIZADA CON ALUMINIO EN MEDIO CONCENTRADO

    Directory of Open Access Journals (Sweden)

    Sonia Moreno

    2009-04-01

    Full Text Available En este trabajo se realizó la síntesis de bentonita pilarizada con aluminio en medio concentrado, empleando ultrasonido en la etapa de intercalación. El agente pilarizante fue preparado por hidrólisis del AlCl3 con NaOH, seguido de precipitación con disolución de Na2SO4 y redisolución en Ba(NO32, y fue caracterizado por fluorescencia de rayos X (FRX, difracción de rayos X (DRX, microscopía electrónica de barrido (SEM y resonancia magnética nuclear de aluminio (27Al-RMN. La arcilla pilarizada fue caracterizada por FRX, DRX y fisiadsorción de N2 a 77 K, revelando propiedades estructurales y texturales comparables a la modificada siguiendo la metodología convencional: suspensiones diluidas y tiempos de intercalación elevados. El empleo de suspensiones concentradas de arcilla-agente pilarizante y la aplicación de ultrasonido en la etapa de intercalación, permiten una disminución en el volumen de agua entre el 90-95 % y una reducción en el tiempo de intercalación entre el 70–93 % respecto al método convencional de pilarización.

  1. CRECIMIENTO DEL MAÍZ EN VERTISOLES CON ALTO ALUMINIO EN LA BAIXADA MARANHENSE PRE-AMAZONIA, BRASIL

    Directory of Open Access Journals (Sweden)

    Alessandro Costa da Silva

    2014-01-01

    Full Text Available Crecimiento del maíz en vertisoles con alto aluminio en la Baixada Maranhense pre-Amazonia, Brasil. El objetivo de este trabajo fue evaluar el crecimiento del maíz en suelos con alto contenido de aluminio. Se midió el efecto del Al3+ en raíces y la cantidad de materia seca (raíz, hoja y tallo de maíz. Se efectuó la caracterización físico-química de cuatro muestras de suelo con alto aluminio colectadas del horizonte Ap, en tres municipios de la región conocida como Baixada Maranhense (Pre-Amazonia, Brasil: Santa Rita (SR, Arari (AR y Vitoria do Mearim (VM y un testigo colectado en el municipio de São Luís, Área del Núcleo de Tecnología Rural (T. El estudio, ejecutado en 2009, se llevó a cabo en invernadero y se utilizó 2 dm3 de suelo por maceta. Asimismo las muestras fueron divididas en muestras con y sin fertilización. La variación en la longitud de la raíz y de materia seca de las hojas difirió significativamente entre tratados con y sin fertilizante, excepto en la muestra de la localidad T. La producción de materia seca de raíz, tallo y hoja fue mayor en todos los suelos cuando se fertilizó. El suelo testigo también superó a todos los demás en cuanto a producción de materia seca en la raíz, posiblemente como resultado de una menor cantidad de Al3+ (1,2 cmolc/dm3 en comparación con los suelos SR, AR y VM (6,8; 8,0 y 7,0 cmolc/dm3 respectivamente. Se concluye la fertilización reduce el efecto detrimental del aluminio en la producción de maíz en la Baixada Maranhense.

  2. Influencia sobre los tratamientos térmicos del contenido de aluminio de aceros no aleados

    Directory of Open Access Journals (Sweden)

    Carreras, L.

    1999-08-01

    Full Text Available The main purpose of this article is to determine the optimal level of aluminum content in plain steels to have the optimal mechanical properties by means of surface heat treatments. Various plain steels with different aluminium content have been studied. The importance of treatment temperature is analyzed. The influence of other factors, like nitrogen content or the homogenous distribution of particles, is evaluated. It is concluded that the aluminum composition of plain steels that are subjected to heat treatments should not exceed 0.02 %.

    El objetivo de este trabajo es determinar el intervalo óptimo de contenidos de aluminio en aceros no aleados para los que se consiguen las propiedades mecánicas óptimas mediante tratamientos térmicos de superficie. Se estudian diferentes coladas de acero en las que varía el contenido de aluminio y las temperaturas de tratamiento. Se evalúa la importancia de otros factores tales como el contenido de nitrógeno y la homogeneidad en la distribución de partículas endurecedoras. Se llega a la conclusión de que los aceros no aleados destinados a tratamientos térmicos no deben tener un contenido de aluminio superior al 0,02 %.

  3. Determinación de los mecanismos de fractura de un material multicapa de aluminio de alta resistencia y excelente tenacidad a impacto basado en la aleación aeroespacial Al 7075

    Directory of Open Access Journals (Sweden)

    Cepeda-Jiménez, C. M.

    2012-08-01

    Full Text Available An aluminium multilayer laminate has been processed by hot rolling. It is constituted by 19 alternated layers of high-strength aluminium alloy (Al 7075-T6, 82 % vol and thinner pure aluminium layers (Al 1050-H24, 18 % vol. The microstructure of the constituent alloys and the composition gradient across the interfaces has been characterized. The multilayer laminate and the as-received aluminium alloys have been tested at room temperature by Vickers microhardness, three-point bend test and impact Charpy test. The outstanding improvement in damage tolerance, which is 18 times higher than that for the as-received Al 7075 alloy, is due to both intrinsic and extrinsic fracture mechanisms operating in the multilayer laminate during mechanical testing.

    En este trabajo se ha procesado mediante laminación en caliente un material multicapa constituido por 19 capas alternadas de aluminio de alta resistencia (Al 7075-T6, 82 %vol y capas de aluminio puro (Al 1050-H24, 18 %vol de menor espesor. Se ha caracterizado la microestructura de las aleaciones constituyentes después del procesado, así como el gradiente de composición generado alrededor de las intercaras. Las propiedades mecánicas a temperatura ambiente, tanto del material multicapa como de las aleaciones de partida, se han estudiado mediante microdureza Vickers, flexión en tres puntos y ensayos de impacto Charpy. El material multicapa procesado presenta una tenacidad a impacto Charpy 18 veces superior a la de la aleación de partida Al 7075. Este espectacular aumento de tolerancia al daño es debido a los mecanismos de fractura, tanto extrínsecos como intrínsecos, que operan en el material multicapa durante las diferentes solicitaciones mecánicas a las que ha sido sometido.

  4. Comportamiento Tribológico de Aluminio Sinterizado y Desgastado Bajo Distintas Condiciones Comportamiento Tribológico de Aluminio Sinterizado y Desgastado Bajo Distintas Condiciones

    Directory of Open Access Journals (Sweden)

    Veridiana Reyes Z.

    2012-02-01

    Full Text Available Wear is one of the most costly damages in industry and research has been directed towards its prevention. This paper deals with the behavior of aluminum pieces, prepared by powder metallurgy, under wear. The samples tested were prepared under different processing conditions (compacting pressure, temperature and sintering time. The wear test was carried out ina pin-in-disc machine, at various rates and wear pressures. The results showed the tribological behavior of aluminum. Also, a comparative study between a 356-aluminium alloy and pure aluminum was carried out, showing the feasibility of attaining similar tribological behavior between a conventional alloy and pure aluminum prepared by powder metallurgy techniques.El desgaste es uno de los daños más costosos para la industria y las investigaciones buscan entender los mecanismos del desgaste que podrían disminuirlo o evitarlo. Este trabajo analiza el comportamiento del aluminio obtenido por metalurgia de polvos cuando se somete a desgaste. Las muestras usadas fueron preparadas bajo diversas condiciones de proceso (presión de la compactación, la temperatura y tiempode tratamiento térmico. Las pruebas de desgaste se realizaron en una máquina de pin-en-disco y fueron probados diferentes valores de velocidad y presión de desgaste. Los resultados obtenidos muestran el comportamiento tribológico del aluminio. Se presenta también un estudio comparativo entre una aleación de aluminio 356 y aluminio puro, demostrándose la viabilidad de lograr un comportamiento tribológico similar entre esta aleación convencional y el aluminio puro preparado por metalurgia de polvos.

  5. EVALUACIÓN DE CAL, SULFATO E HIDROXICLORURO DE ALUMINIO EN LA COAGULACION-FLOCULACION DEL LIXIVIADO DEL RELLENO SANITARIO DE POZA RICA, VERACRUZ

    Directory of Open Access Journals (Sweden)

    Israel Hernández

    2013-01-01

    Full Text Available En el presente artículo se reporta el proceso de clarificación del lixiviado de un basurero de la Ciudad de Poza Rica de Hidalgo, Veracruz, con este fin se utilizó como coagulantes óxido de calcio, sulfato e hidroxicloruro de aluminio. El CaO no presentó capacidad floculante para el lixiviado tratado bajo ninguna de las condiciones ensayadas. El Al2(SO43 mostró buena actividad floculante al tratar el lixiviado obteniéndose 0.97 NTU en el índice de turbidez con 2250 ppm del sulfato de aluminio, por la elevada cantidad de floculante el proceso caro; por otra parte, la floculación de los sólidos suspendidos en el lixiviado se logró una mayor extensión empleando 1.5 ppm de Al2(OH5Cl2*5H2O obteniendo un índice de turbidez de 0.83 NTU, con pH de 7.63.

  6. Durabilidad del aluminio desnudo y anodizado en atmósferas de muy diferentes corrosividades. I. Aluminio desnudo

    Directory of Open Access Journals (Sweden)

    González, J. A.

    2004-08-01

    Full Text Available The behaviour of bare aluminium is studied in atmospheric exposure at 11 natural testing stations with salinity levels ranging between 2.1 and 684 mg Cl-1m-2d-1. In atmospheres of low or moderate aggressivity aluminium behaves as a passive material, though the insignificant corrosion that is produced is sufficient to spoil its appearance. In contrast, at salinity levels of 50 mg Cl-1m-2d-1 or above, aluminium is susceptible to pitting corrosion even in the first year of atmospheric exposure, or in the second year at salinities of s: 10 mg Cl-1m-2d-1 . For comparative purposes, results are included for aluminium protected with an anodic film of 28 μm thickness exposed at the same testing stations. A 28 μm anodic film, correctly sealed, prevents the risk of localised corrosion even in the most unfavourable situations.

    Se estudia el comportamiento del aluminio desnudo durante la exposición atmosférica en 11 estaciones de ensayos naturales, con salinidades que oscilan entre 2,1 y 684 mg Cl-1m-2d-1. En atmósferas de agresividades bajas y moderadas, el aluminio se comporta como un material pasivo, pero la insignificante corrosión que se produce es suficiente para perjudicar el aspecto. Sin embargo, el aluminio es susceptible a la corrosión por picaduras, ya durante el primer año de exposición atmosférica, para salinidades de 50 mg Cl-1m-2d-1 o superiores y, durante el segundo año, para salinidades > 10 mg Cl-1m-2d-1. A efectos comparativos se incluyen resultados de aluminio protegido con un anodizado de 28 μm de espesor, expuesto en las mismas estaciones de ensayo. Un anodizado de 28 μm, correctamente sellado, evita el riesgo de corrosión localizada, incluso en las situaciones más desfavorables.

  7. Comparación de metodologías voltamperométricas adsortivas para la determinación de aluminio en agua potable

    Directory of Open Access Journals (Sweden)

    Miriam Barquero Quirós

    2005-11-01

    Full Text Available La determinación cuantitativa de aluminio en diversas técnicas a nivel de μg/L está sujeta a contaminación e interferencias. El aluminio por técnicas voltamperómétricas directas es difícil de reducir debido a su alto potencial. Para superar este problema, se forman complejos solubles de aluminio, que se adsorben en un electrodo de Hg. Luego se reducen siendo la corriente de pico proporcional a la concentración. Se estudiaron dos diferentes complejos de aluminio con alizarina y con cupferrón; en ambos casos se optimizaron las condiciones experimentales de formación de los complejos tales como pH óptimo, concentración de reactivo acomplejante, las condiciones experimentales de medición fueron opimizadas: potencial de acumulación, tiempo de acumulación, frecuencia, amplitud de pulso, tiempo de equilibrio, se determinaron los parámetros de desempeño de ambas determinaciones: veracidad, ámbito lineal, límite de detección, y límite de cuantificación para la técnica de voltamperometría de onda cuadrada (SWV. El complejo de aluminio-alizarina no es electroactivo, y la alternativa es medir la alizarina residual después de la formación del complejo con aluminio, cuya cinética es muy lenta y debe calentarse 5 minutos a 80 °C. Se procedió al estudio de las condiciones experimentales, siendo el pH de 9,25 determinante. Es necesario que el buffer sea de alta capacidad reguladora para obtener la formación del derivado. El límite de detección obtenido a partir de la desviación estándar de 7 blancos fue 3 μg/L, y el coeficiente de variación de los blancos 8 por ciento, la recuperación promedio para 16 μg/L con n=7, fue de 97 por ciento. Las curvas de calibración se realizaron en un ámbito de 8 a 64 μg/L. La aplicación del método a muestras de agua es posible mediante la previa evaporación de estas. Se desarrolló y se validó una metodología apta para cuantificar aluminio en aguas basada en la reacción de Al con

  8. Corrosión de componentes de aluminio en el reactor RP-10

    OpenAIRE

    Morales Larrea, Soledad; Tenorio de la Cruz, Favio

    1983-01-01

    Se analiza la velocidad de corrosión, por pérdida de peso de placas de aluminio a diversos valores de pH y temperatura en solución acuosa. El estudio se hace simulando las condiciones de trabajo (pH y temperatura) a las que pueden verse sometidas las vainas de aluminio de los elementos combustibles del reactor RP-10.

  9. Impacto de genotipos de Brachiaria tolerantes a aluminio sobre la calidad de un Oxisol de altillanura en el Meta, Colombia

    OpenAIRE

    Oyola, Jaumer Ricaurte

    2006-01-01

    Los suelos de los Llanos Orientales Colombianos presentan limitantes al crecimiento de las plantas. Son muy ácidos, con limitantes físicas como la susceptibilidad a la compactación y fragilidad estructural, son pobres en casi todos los nutrientes, especialmente fósforo, potasio, calcio y magnesio, tienen baja capacidad de intercambio catiónico, saturada predominantemente por aluminio (Al+3). La mayoría de las especies cultivadas son susceptibles a altas concentraciones de Al+3, pero la selecc...

  10. Estudio del proceso de solidificación en fundición de aluminio para brazos del sistema de freno de un ascensor, mediante elementos finitos

    OpenAIRE

    Cangás Herrera, Juan Gabriel; Valverde Paredes, Edgar Alexander

    2014-01-01

    163 hojas : ilustraciones, 29 x 21 cm + CD-ROM 5695 El presente trabajo contiene el estudio del proceso de fundición de aluminio para brazos del sistema de freno de un ascensor eléctrico mediante elementos finitos, con la utilización del software Click2Cast. Se realiza un marco teórico sobre temas inherentes al objeto de este trabajo, como son los procesos de fundición, aleaciones de aluminio, defectología en los procesos de fundición y solidificación de metales, así como una introducció...

  11. El aluminio en el suelo y algunas estrategias de manejo

    OpenAIRE

    Fabio Emilio Forero-Ulloa; Pablo Antonio Serrano-Cely; William Alberto Balaguera-López

    2011-01-01

    El  suelo  está  compuesto por diversos  elementos entre  los que  se destaca el aluminio, como un metal que, en condiciones  normales,    no  afecta  el desarrollo de las plantas,  pero en suelos ácidos  es un factor limitante en el crecimiento de la mayoría de especies vegetales,  con una afectación cercana al 50% del área sembrada  en el ámbito mundial. En Colombia  cerca del  85% de  los  suelos  son ácidos,  por lo cual es  necesario buscar estrategias de manejo  y  permitir  que  estos ...

  12. Crecimiento del maíz en vertisoles con alto aluminio en la Baixada Maranhense pre-Amazonia, Brasil.

    Directory of Open Access Journals (Sweden)

    Alessandro Costa-da Silva

    2014-07-01

    Full Text Available El objetivo de este trabajo fue evaluar el crecimiento del maíz en suelos con alto contenido de aluminio. Se midió el efecto del Al3+ en raíces y la cantidad de materia seca (raíz, hoja y tallo de maíz. Se efectuó la caracterización físico-química de cuatro muestras de suelo con alto aluminio colectadas del horizonte Ap, en tres municipios de la región conocida como Baixada Maranhense (Pre-Amazonia, Brasil: Santa Rita (SR, Arari (AR y Vitoria do Mearim (VM y un testigo colectado en el municipio de São Luís, Área del Núcleo de Tecnología Rural (T. El estudio, ejecutado en 2009, se llevó a cabo en invernadero y se utilizó 2 dm3 de suelo por maceta. Asimismo las muestras fueron divididas en muestras con y sin fertilización. La variación en la longitud de la raíz y de materia seca de las hojas difirió significativamente entre tratados con y sin fertilizante, excepto en la muestra de la localidad T. La producción de materia seca de raíz, tallo y hoja fue mayor en todos los suelos cuando se fertilizó. El suelo testigo también superó a todos los demás en cuanto a producción de materia seca en la raíz, posiblemente como resultado de una menor cantidad de Al3+ (1,2 cmolc/dm3 en comparación con los suelos SR, AR y VM (6,8; 8,0 y 7,0 cmolc/dm3 respectivamente. Se concluye la fertilización reduce el efecto detrimental del aluminio en la producción de maíz en la Baixada Maranhense.

  13. Resistencia a la corrosión en ambiente salino de un acero al carbono recubierto con aluminio por rociado térmico y pintura poli aspártica

    Directory of Open Access Journals (Sweden)

    José Luddey Marulanda Arévalo

    2017-06-01

    Full Text Available Se evaluó la resistencia a la corrosión en ambiente salino del acero 1020 recubierto con aluminio por medio de rociado térmico por arco eléctrico y después se aplicó una pintura poliaspártica. Se observó que este sistema presenta una protección en estos ambientes, reduciendo la velocidad de corrosión, en comparación con un sistema de pintura bicapa, el cual consistía en una capa rica en zinc y otra capa de pintura poliaspártica. Se realizó la caracterización del recubrimiento por medio de Microscopía Electrónica de Barrido (MEB para analizar su comportamiento con respecto al sustrato y a la pintura para conocer variaciones en propiedades como adherencia, topografía y homogeneidad. Se observó que las probetas recubiertas con aluminio por rociado térmico presentan una mayor resistencia a la corrosión en cámara salina que las probetas que no fueron recubiertas y solo estaban protegidas por el sistema bicapa de pintura, aunque la pintura sin rociado térmico tuvo un buen desempeño ya que no falló durante el tiempo estipulado para en ensayo en cámara de niebla salina.

  14. El eurocódigo 9 "Proyecto de estructuras de aluminio"

    Directory of Open Access Journals (Sweden)

    Ramírez, J. L.

    1999-06-01

    Full Text Available Aluminium is an interesting structural material because its lightness and minimum maintenance needs, together with and important strength. The lack of knowledge of design rules with this material owing to the shortage of design guides, together with its higher cost, are factors that leed to the very scarce use of aluminium in the construction of structures. In present article it is dealt with a brief look to the tipology and properties of the structural aluminium alloys, and it is described the content of Eurocode 9 "Design of aluminium structures", approved by CEN (European Committee for Standardization in may 1998 that it is foreseen to be published in Spanish by AENOR in short time.

    El aluminio es un material estructural de interés, por unir ligereza y mínimas necesidades de protección, junto con una resistencia importante. La falta de conocimiento de las reglas de proyecto con el material, debido a la escasa disponibilidad de guías o recomendaciones de diseño, junto con un precio elevado, son factores que condicionan la muy escasa presencia del aluminio en la construcción de estructuras. En el presente artículo se expone una visión sucinta de la tipología y propiedades de las aleaciones de aluminio y se describe el contenido del Eurocódigo 9 "Proyecto de estructuras de aluminio" aprobado por el CEN (Comité Europeo de Normalización en mayo de 1998 y que aparecerá en castellano en breve publicada por AENOR, como Norma Europea Experimental.

  15. Efecto del calcio sobre la toxicidad aguda de aluminio en alevines de trucha arcoiris (Oncorhynchus mykiss expuestos en aguas de diferente pH

    Directory of Open Access Journals (Sweden)

    Rolando Vega

    2015-05-01

    Full Text Available En la producción de alevines de salmón de la región de la Araucanía (sur de Chile se presentan importantes eventos de mortalidad aguda sin rasgos patológicos aparentes. El problema se focaliza en ejemplares de 0,2 a 1 g y las causas apuntan a procesos de acidificación del pH del agua y a la presencia de ciertos metales pesados, entre los cuales destaca el aluminio, que alcanza concentraciones más allá de los rangos de tolerancia de los peces. La información científica indica que concentraciones de 5 mg Ca L-1 en el afluente son suficientes para mantener a salvo los peces del efectos tóxico del aluminio. Sin embargo, los problemas en la producción de alevines de salmón indican que se requiere un mayor conocimiento científico y evidencia experimental que soporte el desarrollo de procesos y tecnologías para el tratamiento de los afluentes de las pisciculturas chilenas. En este trabajo se evaluó el efecto de cuatro concentraciones de calcio (0, 5, 10 y 20 mg Ca L-1 sobre la toxicidad aguda de 500 μg Al L-1 en alevines de trucha arcoiris (Oncorhynchus mykiss de 0,1 g en agua de cultivo a pH 5, 6 y 7. El objetivo del trabajo fue determinar la dosis de calcio que reduce la toxicidad aguda de aluminio y los tiempos mínimos de reacción que podrían disponer los piscicultores para tomar medidas preventivas ante una concentración aguda de aluminio en el agua de cultivo. Los resultados indican que antes de 8 h de exposición a una concentración tóxica de aluminio los piscicultores deberían asegurar en el agua de cultivo una dosis superior a 10 mg Ca L-1 y un pH >6 como medida remedial para reducir el efecto de intoxicación aguda causada por aluminio.

  16. Síntesis coloidal de materiales nanoestructurados de Al-ZrAl3: Propiedades mecánicas mediante el ensayo miniatura de punzonado

    Directory of Open Access Journals (Sweden)

    Díaz, L. A.

    2009-08-01

    Full Text Available This work describes a new method to obtain Al-Zr intermetallic nanostructured materials by using a colloidal processing technique. The combination of Al powders and zirconium IV-propoxide (C12H28O4Zr under controlled conditions results in a metal matrix composite with a homogeneous dispersion of intermetallics. Synthesis was carried out in a tubular furnace under argon and by hot pressing under the same atmospheric conditions. XDR and SEM were used to identify the intermetallic nanoparticles. The Vickers hardness of the ZrAl3 nanocomposites and the mechanical behaviour by small punch test were studied.

    En este trabajo se describe un nuevo método de procesamiento coloidal para obtener materiales nanoestructurados de base aluminio con partículas intermetálicas ZrAl3. A partir de una mezcla controlada en alcohol, de polvos de aluminio con un alcóxido precursor de zirconio (C12H28O4Zr se obtiene, mediante un tratamiento térmico en un horno convencional con atmósfera controlada o por prensado uniaxial en caliente, un polvo nanoestructurado formado por cristales de aluminio sobre los que cristalizan, de forma homogénea, nanopartículas intermetálicas de ZrAl3. La identificación del intermetálico se efectuó por difracción de rayos X y microscopía electrónica de barrido. El comportamiento mecánico de los materiales nanoestructurados desarrollados se evaluó a partir de ensayos de dureza y mediante el ensayo miniatura de punzonado (EMP. Los resultados muestran que la presencia del intermetálico de zirconio hasta un 1,0 % (en peso de zirconio aumenta la dureza y rigidez de la matriz de aluminio, al tiempo que incrementa su resistencia mecánica (límite elástico y resistencia a la tracción.

  17. Solubilidad y reacción del aluminio en el suelo

    Directory of Open Access Journals (Sweden)

    Fánor Casierra-Posada

    2011-02-01

    Full Text Available El aluminio que, en condiciones ácidas, proviene de los minerales hacia la solución del suelo, o que está presente en soluciones nutritivas con pH menor a cuatro, aparece principalmente como Al(OH2. La mineralogía, el grado de cristalinidad y de reactividad de los resultantes de la precipitación de Al3+, se ven influenciados principalmente por el pH, los minerales de las arcillas, y por la naturaleza y concentración de los ácidos orgánicos e inorgánicos presentes en los suelos. Existen muchas posibles fases minerales que podrían intervenir en la solubilidad de Al 3+ en los horizontes minerales del suelo, tales como: gibsita, alofano, imogolita y caolinita. En los andosoles, el alofano también contribuye a que se presenten concentraciones altas de Al 3+. En muchos suelos, la solubilidad de Al 3+ también puede estar determinada por las reacciones que conducen a la formación de complejos con la materia orgánica, al menos a corto plazo. El poder buffer de esos suelos depende, ampliamente, de la relación de intercambio H+/Al 3+; esto es, del número de protones consumidos por la fase sólida, cuando se libera Al 3+. En este artículo, se hizo una revisión detallada de los factores responsables de la disponibilidad de Al 3+ en el suelo, tales como solubilidad, formación de complejos con la materia orgánica y la relación de intercambio H+/Al 3+.

  18. Tratamiento del polvo de aluminio mediante disolución acuosa

    Directory of Open Access Journals (Sweden)

    López, F. A.

    2004-10-01

    Full Text Available Aluminium dust from aluminium remelting industry is a hazardous residue because of its high reactivity in the presence of water. In order to apply the new European Directive about landfill of waste, a study of its hydrolysis was carried out. The influence of temperature, time and pH on the hydrolysis of the aluminium dust was studied. The hydrolysed solids were characterized by XRD and AAS; in the aqueous solutions the pH and the ionic conductivity were determined. The evolved gases were analysed by mass spectrometry. The reactivity of the dust, before and after hydrolysis, was investigated by analysing the ammonia, hydrogen sulphide and metallic aluminium. By hydrolysis at 60 °C and 48 h a much lower reactive material was obtained which could be disposed with minimal environmental impact.

    El polvo de aluminio es un residuo generado en la metalurgia secundaria del aluminio y considerado peligroso como consecuencia de su elevada reactividad en presencia de humedad. Con objetivo de buscar un procedimiento de pretratamiento de dicho residuo, de acuerdo con la Directiva Europea sobre vertederos, se ha realizado el estudio del comportamiento del polvo de aluminio en medio acuoso. Para ello, se han analizado la influencia de la temperatura, el tiempo y el pH de reacción en su hidrólisis. Los sólidos hidrolizados se caracterizaron mediante EAA y DRX, mientras que en las soluciones acuosas resultantes se determinaron el pH y la conductividad iónica. Los gases liberados durante el proceso de hidrólisis se analizaron mediante espectrometría de masas. Asimismo, se ha determinado la reactividad del residuo antes y después de la hidrólisis, analizando amoniaco, sulfuro de hidrógeno y aluminio metálico. La hidrólisis, a 60 °C y después de 48 h, permite obtener material de muy baja reactividad que podría ser almacenado en vertedero.

  19. Formas de hierro y aluminio en suelos con diferentes usos en la zona norte del departamento del Magdalena, Colombia

    Directory of Open Access Journals (Sweden)

    José Rafael Vásquez Polo

    2014-12-01

    Full Text Available En el estudio se evaluaron las diferentes formas de hierro (Fe y aluminio (Al presentes en suelos cultivados y en áreas de bosque de la zona norte del departamento del Magdalena (Colombia. Se seleccionaron seis zonas de muestreo localizadas entre 0 y 1000 m.s.n.m. Se utilizaron tres técnicas selectivas de extracción de Fe y Al con los agentes extractantes: pirofosfato de sodio, oxalato ácido de amonio, y ditionito citrato bicarbonato. Los contenidos totales de Fe y Al fueron determinados mediante un ataque ácido y cuantificación por absorción atómica. El análisis de varianza multivariado mostró diferencias significativas (P 3% del Al total, lo que sugiere que un alto contenido de Al forma parte de estructuras cristalinas.

  20. ANÁLISIS ESTRUCTURAL Y MORFOLÓGICO DE PELÍCULAS DE NITRURO DE ALUMINIO OBTENIDAS POR DEPOSICIÓN DE LÁSER PULSADO

    Directory of Open Access Journals (Sweden)

    Jaime Andrés Pérez Taborda

    2010-01-01

    Full Text Available En este trabajo, se presentan los resultados preliminares de peliculas nanoestructuradas de nitruro de aluminio (AlN, que fueron depositadas con el metodo de deposicion por laser pulsado (PLD. Al efecto, se utilizo un laser Nd:YAG (¿É=1064nm, que impacto un blanco de aluminio de alta pureza (4N, en una atmosfera de nitrogeno. Se utilizaron como sustratos portaobjetos de vidrio, Si3N4 (100 y Si (100. El tiempo de deposicion fue de 15 minutos a una fluencia del laser 7 J/cm2 y a temperatura ambiente. El espesor de las peliculas fue de 50 nm medido con un perfilometro. Para estudiar la influencia del nitrogeno en las peliculas delgadas de AlN, se vario la presion del gas ambiente entre (3 y 4 mTorr. Igualmente se estudió la influencia del sustrato en las propiedades morfológicas de las películas delgadas de AlN. La nanoestructura de las películas se determinó mediante microscopia electrónica de barrido (SEM, y microscopia de fuerza atómica (AFM; la composición química, utilizando la técnica de espectroscopía de rayos X por dispersión de energía (EDX. La estructura cristalina fue estudiada con difracción de rayos X (DRX, para la película de 4 mTorr sobre un sustrato de Si3N4 (100, y se encontró una estructura policristalina con reflexiones de los planos (002, asociados a la estructura tipo wurtzita del AlN.

  1. Un hidrogel de hidróxido de aluminio para eliminar el arsénico del agua

    Directory of Open Access Journals (Sweden)

    Luján Juan Carlos

    2001-01-01

    Full Text Available Objetivos. Describir la síntesis y los resultados preliminares de la aplicación de un hidrogel de hidróxido de aluminio que, agregado directamente al agua, pueda lograr la eliminación total del arsénico, cualquiera que sea la naturaleza del agua y el estado de oxidación del metaloide. Métodos. Las materias primas utilizadas para obtener el hidrogel de hidróxido de aluminio fueron: sulfato de aluminio hidratado (que se utiliza para potabilizar aguas, hipoclorito de calcio en polvo, hidróxido de amonio y agua destilada (cuando el gel se preparó a escala de laboratorio y agua de ósmosis inversa de igual o mejor calidad que el agua destilada (cuando se produjo el gel a escala piloto. El control de calidad del producto final consistió en la determinación de su capacidad para adsorber el arsénico y la realización de pruebas bacteriológicas para demostrar su esterilidad. El producto fue aplicado a muestras de agua a las que se añadió arsénico en el laboratorio y a muestras de aguas arsenicales naturales procedentes de la provincia de Tucumán, Argentina. Para el análisis del arsénico en el agua se utilizó el método colorimétrico del dietilditiocarbamato de plata. Resultados. La aplicación del hidrogel proporcionó una gran reducción del arsénico. Tanto en las aguas arsenicales naturales como en las artificiales, después del tratamiento las concentraciones de arsénico quedaron por debajo del límite de detección del método analítico utilizado (0,01 partes por millón. Las pruebas bacteriológicas del producto terminado revelaron la ausencia de bacterias viables. Conclusiones. La aplicación del hidrogel de hidróxido de aluminio proporcionó la deseada reducción de la concentración de arsénico en el agua. Este método de desarsenización es barato y fácil de utilizar en poblaciones rurales dispersas de zonas afectadas por el hidroarsenicismo que carecen de agua potable e infraestructura sanitaria y eléctrica.

  2. DETERMINACIÓN DEL INDICADOR DE RIESGOS INDUSTRIALES DE PLANTAS REDUCTORAS DE ALUMINIO PRIMARIO EN VENEZUELA METODOLOGÍA SATPRO

    Directory of Open Access Journals (Sweden)

    Liliana Manduca Alvarado

    2004-11-01

    Full Text Available

    En el trabajo se determina el indicador de riesgos industriales en el sector productor de aluminio, del área de Reducción de Aluminio Primario en la zona de Guayana, Venezuela. Se utilizó la metodología SATPRO, en primer lugar porque permite reducir los accidentes de trabajo y las enfermedades profesionales y por ende, sus costos; en segundo lugar permite integrar la política de prevención de riesgos en las restantes políticas de la empresa y en su estrategia empresarial; y en tercer lugar, porque se evitarán las sanciones administrativas, apoyando a la gestión administrativa de la empresa y les permitiría realizar estrategias operacionales en la productividad, logrando utilidades sustanciales y cumplir con la nueva Ley de Prestaciones e Indemnizaciones por Accidentes de Trabajo y Enfermedades Ocupacionales, actualmente en discusión en el país donde se exigirá el pago de impuestos, por parte de la empresa evaluada, al gobierno, dependiendo del riesgo detectado.

  3. Comportamiento frente al desgaste en materiales compuestos de aluminio reforzados con partículas cerámicas

    Directory of Open Access Journals (Sweden)

    Busquets-Mataix, D.

    2004-04-01

    Full Text Available The present work deals with the wear behaviour on AA6061 based aluminium matrix composites reinforced with different kinds of ceramic particles: TiB2, B4C, Si3N4, Al2O3 y SiC. Composites were obtained by means of a solid-state consolidation method, combining both powder metallurgy processing and hot extrusion. The study carried out was based on a pin-on-ring apparatus under dry sliding conditions (dry friction. Both friction coefficient and wear rate were measured for each composite. Scanning Electron Microscope (SEM was used to analyse wear and the tribolayer formed. Results show that wear rate is lower in composites than in the unreinforced alloy in every case, as expected. Differences among composites are probably related to different particle size rather than nature of reinforcements. On the other hand, friction coefficient do not show a trend on composites, being lower than the base alloy in some cases and higher in others.

    El presente artículo trata sobre las propiedades tribológicas en materiales compuestos de matriz de aleación de aluminio AA6061, reforzados con partículas cerámicas de diferente naturaleza: TiB2, B4C, Si3N4, SiC y Al2O3. Los materiales compuestos fueron obtenidos mediante un procedimiento de consolidación en estado sólido que combina la pulvimetalurgia con un proceso de extrusión en caliente. El estudio tribológico realizado se basó en una metodología de ensayo del tipo pin-on-ring con deslizamiento en seco (sin lubricación. Se analizaron para cada caso el coeficiente de rozamiento y la tasa de desgaste en función de la distancia de deslizamiento. Asimismo, las muestras ensayadas se observaron mediante microscopía electrónica de barrido. Los resultados obtenidos demuestran que las tasas de desgaste de los compuestos son inferiores en todos los casos a los de la matriz sin reforzar. Entre los compuestos, las diferencias encontradas son debidas al tamaño medio de las partículas de refuerzo, obteni

  4. Factores que controlan las propiedades texturales de arcillas intercaladas con disoluciones de circonio y aluminio

    Directory of Open Access Journals (Sweden)

    Gil, A.

    2000-08-01

    Full Text Available The texture development of a saponite and a montmorillonite, intercalated with zirconium and aluminium oligomers, after calcination at 500 ºC has been studied. Remarkable differences were observed among samples, depending on the source of the intercalating polycations and the parent material. On calcining, the alumina pillared clays suffered noticeable specific surface area and micropore volume losses, which have been related to the interlayer and interpillar distances of the samples. On the contrary, the zirconia pillared clays showed a slight surface area increase, which affected both micropores and mesopores and could be due to the combined effect of the thermal decomposition of the zirconium oligomers and the possible presence of mesoporous ZrO2 particles.

    En este trabajo se ha estudiado la evolución de las propiedades texturales de una saponita y una montmorillonita intercaladas con disoluciones de circonio y aluminio tras calcinación a 500 ºC. Los sólidos presentaron un diferente comportamiento en función de la naturaleza de la disolución de intercalación y de la arcilla empleada. Tras calcinación, la superficie específica y el volumen microporoso de las arcillas intercaladas con disoluciones de aluminio disminuyeron de manera importante, lo cual se ha relacionado con las distancias interlaminar e interpilar que presentaron los materiales intercalados. Por contra, las superficies específicas de las arcillas intercaladas con disoluciones de circonio aumentaron, probablemente gracias al efecto combinado de la descomposición térmica de los ligandos orgánicos unidos al circonio en los policationes y la posible presencia de partículas mesoporosas de ZrO2 sobre la superficie de los sólidos.

  5. Contaminación con aluminio en sangre en personas dializadas en dos hospitales de Colombia

    OpenAIRE

    Roberto Fernández-Maestre

    2012-01-01

    Objetivo: Se relacionó el grado de contaminación con aluminio en suero sanguíneo de pacientes sometidos a tratamientos de diálisis con el contenido de aluminio en los líquidos de diálisis que usaron estos pacientes y las alteraciones que mostraron en su salud. Método: Se analizaron por espectrometría de absorción atómica con horno de grafito (EAA) muestras de suero sanguíneo de 34 pacientes y dializados de dos instituciones hospitalarias de la ciudad de Cali-Colombia. Las muestras de suero se...

  6. Modelo predictivo del espesor de la capa de óxido y microdureza en aluminio Al3003-B14 y Al6063-T6 anodizado usando análisis multifactorial Oxide film thickness and microhardness prediction model of Al3003-B14 and Al6063-T6 anodized aluminum using multifactorial analysis

    Directory of Open Access Journals (Sweden)

    Leonardo Eladio Vergara Guillén

    2011-08-01

    Full Text Available En esta investigación se modela a partir de los parámetros del proceso el espesor de la capa de óxido y la microdureza de los aluminios Al3003 y Al6063 anodizados. Para ello se realizaron estudios de la microdureza y espesor de capa de la superficie anodizada, utilizando técnicas de análisis multifactorial y diseño robusto. Se establecieron los siguientes niveles de los parámetros del proceso: temperatura [15 °C, 25 °C], tiempo [30 min; 60 min], concentración de electrolito [1,2 M; 2 M], densidad de corriente [1 Amp/dm²; 3 Amp/dm²], aluminio [Al3003,Al6063] y como variable de ruido, la deformación plástica [0%, 10%, 20%, 30%]. Se propuso un diseño fraccionado 2(7-2 mixto, con el cual se efectuó un total de 48 pruebas usando soluciones electrolíticas de ácido sulfúrico. La medición de microdureza se realizó con un indentador Vickers con carga de 400 g; el espesor de la capa de óxido se captó mediante microscopia electrónica. A los resultados se les realizó un análisis de varianza (ANOVA, para determinar los factores significativos y la robustez de los efectos. Se encontraron resultados de microdureza [HV] [85,74-308,87]; y espesor de óxido [µm] [12,82- 94,69]. Finalmente, se muestran los modelos de predicción de cada una de las respuestas en función de los factores significativos estas ecuaciones permitirán seleccionar la microdureza y espesor de la capa de óxido para cumplir los requerimientos de un producto particular mediante una selección apropiada de los parámetros del proceso.In this research, the thickness of the oxide layer and the microhardness of anodized aluminum Al3003 and Al6063 are modeled based on process parameters. To this end, studies of the microhardness and the thickness layer of the anodized surface were made, via techniques of multifactorial analysis and robust design. The following levels of the process parameters were established: temperature [15°C, 25°C], time [30min; 60min

  7. Cinética de formación del Al2O3 en capas de aluminio estudiada mediante mediciones eléctricas

    Directory of Open Access Journals (Sweden)

    Oliva, A. I.

    2004-08-01

    Full Text Available In this work a simple method for monitoring the low temperature oxidation of aluminum thin films, which is based on measurements of electrical resistance using the four-probe technique, is proposed. Kinetic growth data of the aluminum oxide layer, obtained using different values of applied current on as-deposited metallic films is presented. The temperature gradient measured on the films were 2 °C and 9 °C when the corresponding applied currents were 0.1A and 0.2 A. The obtained data show a good agreement with the Cabrera-Mott`s model for low temperature oxidation of metals. From kinetic curves, values of the energy barrier (U and of the electrostatic potential (V were obtained, which are reasonable with the values reported in the literature. The sample with a larger current applied, exhibited a higher oxidation rate due to a thermal effect and by the larger electrostatic potential established across the oxide layer. This simple method can be interesting to monitoring and controlling the oxidation process.En este trabajo se propone un método sencillo para el seguimiento del proceso de oxidación de capas delgadas de aluminio, basado en mediciones de la resistencia eléctrica usando la técnica de cuatro puntas en línea. Se presentan datos de cinética de crecimiento de la capa de óxido de aluminio para dos muestras recién depositadas a las que se aplicaron valores distintos de corriente. Los cambios de temperatura medidos fueron de 2 °C y 9 °C para corrientes aplicadas de 0.1 A y 0.2 A. Los datos muestran buen acuerdo con el modelo de Cabrera-Mott para oxidación de metales en baja temperatura. A partir de las curvas de crecimiento se obtuvieron valores de la barrera de energía (U y del potencial electrostático (V, razonables con los reportados en la literatura. La muestra con mayor corriente aplicada se oxidó más rápido debido al efecto térmico ya que se estableció un mayor potencial electrostático a través de la capa de

  8. Evolución de las propiedades mecánicas de un residuo de la metalurgia secundaria del aluminio estabilizado con yeso

    Directory of Open Access Journals (Sweden)

    Tayibi, H.

    2005-08-01

    Full Text Available Aluminium dust from aluminium remelting industry is a hazardous residue because of its high reactivity in the presence of water (production of ammonia, methane, hydrogen sulphide ..., potential aluminothermy and its content in leaching heavy metals. In order to apply the new European Directive about landfill of waste, a Stabilization/Solidification (S/S process was developed in the CENIM with the aim of decreasing its reactivity and to assure an easy transport and storage of the residue. Gypsum was used as a binder material. This work summarizes the study of the mechanical properties of the stabilized residue en comparison with the gypsum ones. The reactivity of the dust, before and after the S/S process was investigated by analysing the ammonia and metallic aluminium

    El polvo de aluminio es un residuo de la metalurgia secundaria del aluminio, generado en la molienda y clasificación de las escorias resultantes de los procesos de fusión de chatarras. Se considera un residuo peligroso debido a su elevada reactividad al entrar en contacto con la humedad ambiental (producción de metano, amoniaco y sulfuro de hidrógeno, entre otros, su potencial aluminotermia y su contenido en metales pesados lixiviables. Conforme a la entrada en vigor de la nueva Directiva Europea sobre vertederos, así como a la implementación de la Directiva sobre Control Integrado y Prevención de la Contaminación, que obliga a transformar los residuos peligrosos en materiales inertes antes de su almacenamiento, se ha desarrollado un procedimiento de Estabilización/Solidificación (E/S del polvo de aluminio, basado en la fuerte acción deshidratante del yeso. El objetivo, además de la obtención de un material menos reactivo, era conseguir unos aglomerados consistentes que pudieran ser fácilmente transportados y manipulados. En este trabajo, se ha estudiado la evolución de las propiedades mecánicas, tales como las resistencias a flexotracción, a compresión y

  9. Oxidación selectiva de hidrocarburos aromáticos, en fase gaseosa, catalizada por fosfatos mixtos vanadilo-aluminio

    OpenAIRE

    Siles Sorribás, María Teresa

    2014-01-01

    El objetivo principal de la Tesis, ha sido la síntesis, por un método sol-gel, nuevos catalizadores de vanadio-aluminio-fósforo en los que se han modificado la relación molar Al/V (0.2¿2); la sal de vanadio de partida (VO3Cl y NH4VO3) y el tratamiento térmico (450¿750ºC). Asimismo, se han sintetizado, a modo de referencia, sistemas vanadio-fósforo. Con el fin de determinar la influencia que dichas variables tienen sobre su composición, propiedades texturales, estructurales, ácido-base y re...

  10. Resistencia al desgaste de recubrimientos de bronce al aluminio producidos con técnica de proyección térmica//Wear resistance of aluminum bronze coatings produced by thermal spray

    Directory of Open Access Journals (Sweden)

    Dayan Carolina Cárdenas-Feria

    2015-09-01

    Full Text Available Se estudió la resistencia al desgaste adhesivo de recubrimientos de bronce al aluminio depositados con la técnica de proyección térmica por llama sobre bronce fosforado SAE 62. Los recubrimientos fueron fabricados variando las presiones parciales de los gases de combustión, oxígeno y acetileno. El material utilizado fue caracterizado estructuralmente mediante difracción de rayosX (X-ray diffraction, XRD y el estudio morfológico mediante microscopía electrónica de barrido (Scanning electron microscopy, SEM. La resistencia al desgaste adhesivo de los recubrimientos se determinó por medio del ensayo de bola sobre disco, utilizando como bola una esférica de acero 100Cr6. Los resultados obtenidos permiten establecer que los recubrimientos proyectados con una presión de oxigeno de 78 psi y una presión de acetileno de 8 psi presentan la mejor resistencia al desgaste en comparación a los tratamientos producidos. El modo de falla de desgaste en los recubrimientos producidos es discutido en esta investigación.Palabras clave: desgaste abrasivo y adhesivo,  proyección térmica,  recubrimientos.______________________________________________________________________________AbstractWe studied the adhesive wear resistance of aluminum bronze coatings deposited by thermal spray on phosphor bronze SAE 62 substrates. The coatings were deposited by varying the partial pressures of the combustion gases: oxygen and acetylene. The structural characterization was made through X-ray diffraction (XRD and the morphological analysis was performed by scanning electron microscopy (SEM. The adhesive wear resistance of the coatings was determined by the bole on disc test using a spherical ball made of steel 100Cr6 and with a diameter of 6 mm. The results obtained show that the coating projected with an oxygen pressure of 78 psi and an acetylene pressure of 8 psi have the better wear resistance compared with the substrate and the others treatments deposited

  11. Influencia de la composición y el tratamiento térmico en las propiedades mecánicas de aleaciones de bronce al aluminio

    Directory of Open Access Journals (Sweden)

    Cenoz-Echeverría, I.

    2007-08-01

    Full Text Available Aluminium bronzes are copper-base alloys containing aluminium within the limits between 5-12 %. Additions of Fe, Ni and Mn are used as alloying elements forming a family of complex alloys noted for their exceptional strength and corrosion resistance. In present paper the Ni:Fe ratio and heat treatments have been analyzed by determining the mechanical properties for three different aluminium bronze alloys containing Cu-Al10-Fe3, Cu-Al10-Fe5-Ni5 and Cu-Al10-Fe4-Ni8. The effect of as cast, quenched and quenched and tempered structures has been investigated regarding hardness, proof and ultimate tensile strength, elongation, modulus of elasticity, Poisson ratio, fracture toughness, fatigue strength, crack propagation and Charpy impact properties. The influence of temperature has been studied by testing the elastic modulus, Poisson ratio, the proof stress, tensile strength and the Charpy impact properties at –20 °C, 24 °C and 100 °C.

    Los cuproaluminios son aleaciones de cobre con contenidos de aluminio del 5-12 % que pueden incorporar hierro, níquel, y manganeso para formar una familia de aleaciones con unas excelentes propiedades de resistencia mecánica y a la corrosión. En el presente artículo se estudia el efecto que la relación Ni:Fe y que los tratamientos térmicos ocasionan en las propiedades mecánicas como dureza, límite elástico, tensión de rotura, alargamiento, módulo de elasticidad, coeficiente de Poisson, tenacidad a la fractura estática, resiliencia, fatiga y propagación de grieta. Para ello, se analizan tres aleaciones en tres estados. Las composiciones nominales son Cu-Al10-Fe3, Cu-Al10-Fe5-Ni5 y Cu- Al10-Fe4-Ni8. Las estructuras de las aleaciones son las correspondientes a: bruto de colada, temple y temple seguido de revenido. La caracterización del módulo de elasticidad y coeficiente de Poisson, así como los ensayos de tracción y resiliencia, se realizan a –20 °C, 24 °C y 100 °C.

  12. The efficiency at industrial scale of a thermodynamic model for desulphurization of aluminium killed steels using slags in the system CaO-MgO-Al2O3-SiO2.

    Directory of Open Access Journals (Sweden)

    Butnariu, I.

    2010-02-01

    Full Text Available In this paper are presented the results of some desulphurization trials in the ladle carried out at industrial scale for steels with low carbon, low alloyed and aluminum killed, using basic slag and argon bubbling. The main variables of treatment have been established on the basis of a thermodynamic model that includes parameters as sulphur capacity of the slag, optical basicity of oxides and of the slags, the activities of oxides in the slags and activities of elements in the liquid steel. Sulphur contents at the end of treatment, are close to the values predicted by the model. Low sulfur levels achieved in the process, facilitate the subsequent treatment with calcium to modify the inclusions. Finally an evaluation is presented concerning the effects resulting from the reoxidation of the melt on the main indicators, showing the efficiency of the applied treatment for desulphurization.En este trabajo se presentan los resultados de algunos ensayos de desulfuración en cuchara, llevados a cabo a escala industrial, para aceros con bajo contenido en carbono, de baja aleación y calmados con aluminio, utilizando escorias basicás y corriente de argón. Las principales variables del tratamiento se han establecido sobre la base de un modelo termodinámico que incluye parámetros como la capacitad de captación de azufre por las escorias, la basicidad óptica de los óxidos y de las escorias , las actividades de los óxidos en las escorias y las actividades de los elementos en el acero liquido. Los contenidos de azufre al final de tratamiento están cerca de los valores predichos por el modelo. Los bajos niveles de azufre alcanzados en el proceso, facilitan el posterior tratamiento con calcio para modificar las inclusiones. Se presenta, finalmente, una evaluación de los efectos derivados de la reoxidación del fundido sobre los principales indicadores que muestran la eficiencia del tratamiento de desulfuración aplicado.

  13. Estudio de la protección del refuerzo de partículas de SiC mediante barreras activas por sol-gel en materiales compuestos de matriz de aluminio

    Directory of Open Access Journals (Sweden)

    Ureña, A.

    2004-04-01

    Full Text Available A microcrystalline, homogeneous and transparent sol – gel silica coating has been developed to avoid the degradation and improve the wettability of aluminium matrix composites reinforced with SiC particles. Composite aluminium matrix samples have been made by cold powder compaction, and the coating efficiency has been checked by melting the samples several temperature and times. The coating reduces the appearance of Al4C3, showing that the degradation resistance of the new material is much higher than that of the uncovered SiC particles composite one.

    Con objeto de prevenir la degradación y mejorar la mojabilidad de los materiales compuestos de matriz de aluminio reforzados con partículas de SiC se ha desarrollado un recubrimiento microcristalino, homogéneo y transparente de SiO2 obtenido por el método sol-gel. La eficacia del recubrimiento como barrera se ha comprobado realizando ensayos de fusión a diferentes tiempos y temperaturas sobre pastillas de material compuesto de matriz de aluminio obtenidas por compactación en frío de polvos. El recubrimiento limita la formación de Al4C3, lo que indica que la resistencia a la degradación del nuevo material es muy superior a la del fabricado con partículas de SiC sin recubrir.

  14. Puesta a punto de un equipo de anodizado para aleaciones de aluminio

    OpenAIRE

    Vélez Leache, Javier

    2014-01-01

    En este proyecto se realiza la anodización, en planta piloto de laboratorio, de muestras de aluminio de pequeñas dimensiones, sometiendo posteriormente estas muestras anodizadas a los ensayos exigidos por las normas ISO para este tratamiento de superficie Máster Universitario en Ingeniería de Materiales y Fabricación Unibertsitate Masterra Materialen eta Fabrikazioaren Ingeniaritzan

  15. Comportamiento dieléctrico de compuestos epoxi/aluminio/BaTiO3

    Directory of Open Access Journals (Sweden)

    Castro, M. S.

    2009-06-01

    Full Text Available In order to improve the dielectric behaviour of epoxi/BaTiO3, in this work the influence of micrometric aluminum metal flakes (Al, on the dielectric properties of epoxy / BaTiO3 composites was studied. Epoxy resin, Al and BaTiO3 were mixed using an ultrasonic mixer and composites were deposited onto glass substrates by dipping technique. Obtained materials presented good dielectric properties at room temperature, and relaxation process appeared due to the resin behaviour. Obtained results were compared with those reported in literature for similar systems.Con el objetivo de mejorar el comportamiento dieléctrico de los compuestos epoxi/BaTiO3, en este trabajo se estudió la influencia de partículas metálicas de aluminio (Al, con forma de escamas y tamaño micrométrico, sobre las propiedades dieléctricas de sistemas epoxi / BaTiO3. El material compuesto fue obtenido por la técnica de inmersión o “dipping”. La mezcla de los componentes fue llevado a cabo en mezclador ultrasónica y la deposición se realizó sobre sustratos de vidrio. Los materiales obtenidos presentaron buenas propiedades dieléctricas a temperatura ambiente, sin alcanzar el límite de percolación, y los fenómenos de relajación fueron generados por los dominios de la resina. Los valores obtenidos fueron comparados con los reportados en la bibliografía para sistemas similares.

  16. PELÍCULAS DELGADAS DE ZnO IMPURIFICADAS CON ALUMINIO Y FLÚOR PREPARADAS POR SOL-GEL

    Directory of Open Access Journals (Sweden)

    Salvador Tirado

    2012-01-01

    Full Text Available Se han fabricado películas delgadas de óxido de cinc impurificadas con aluminio y flúor (ZnO:Al:F, mediante el proceso de sol-gel y la técnica de inmersión repetida. Las películas se depositaron sobre sustratos de vidrio sodo-cálcico. Se ha estudiado el efecto del envejecimiento del sol y el espesor de las películas sobre estructura, morfología, propiedades ópticas y eléctricas. Películas policristalinas ZnO:Al:F resultaron con orientación preferencial del plano (002. Resultó un tamaño de cristal para las películas en el rango de 18-39 nm. En las mejores películas se registraron valores de 5x10-1 y 12x10-1 Ω cm para la resistividad. Las películas presentaron una transmitancia de 75 a 85%. De los espectros UV se evaluó un ancho de banda de 3.31 a 3.34 eV para las películas. Las películas ZnO:Al:F al 0.5% at., presentan propiedades físicas y químicas tales, que podrían aplicarse en celdas solares en tecnología de película delgada.

  17. Polvos de Al-Al3Ti obtenidos mediante aleado mecánico y tratamiento térmico

    Directory of Open Access Journals (Sweden)

    Gallardo, J. M.

    2005-12-01

    Full Text Available Mixed powders of aluminium and titanium (10 wt % have been mechanically alloyed in an Attritor mill. A metastable solution of titanium in an aluminium matrix is obtained. Changes produced on shape and particle size, structure and microstructure, have been studied when milling time varies between 2 and 10 h. The final processing is carried out for a milling time of 10 h, with approximately 9 wt % of titanium dissolved in the matrix. Finally, a heat treatment is carried out at different temperatures, up to a maximum of 625 °C, which produces the precipitation of different phases such as different structures of Al3Ti and Al4C3. The appearance of these second phases is characterized according to the selected heat treatment temperature.Polvos mezclados de aluminio y titanio (10 % en peso han sido aleados mecánicamente en un molino Attritor, obteniéndose una solución metaestable de titanio en la matriz de aluminio. Se han estudiado los cambios producidos en la forma y tamaño de las partículas, estructura y microestructura, al variar el tiempo de molienda entre 2 y 10 h. El procesado final se realiza para un tiempo de 10 h, habiéndose disuelto aproximadamente un 9 % en peso de titanio. Finalmente, se realiza un tratamiento térmico a diversas temperaturas, hasta un máximo de 625 °C, lo que produce la precipitación de diversas fases, como distintas estructuras de Al3Ti y Al4C3. La aparición de estas segundas fases es caracterizada en función de la temperatura de tratamiento utilizada.

  18. Oxidación en vapor de agua a 700 ºC y 750 ºC del acero inoxidable AISI 317 recubierto con aluminio por CVD-FBR.

    Directory of Open Access Journals (Sweden)

    Jose L. Marulanda

    2014-01-01

    Full Text Available Se realizó la oxidación del acero inoxidable austenítico AISI 317 recubierto con aluminio por deposición química de vapor en lecho fluidizado, a temperaturas de 700 °C y 750ºC, en un ambiente con 100% vapor de agua, para evaluar su comportamiento. Se realizaron curvas de ganancia de masa y las películas de óxidos se analizaron por medio de SEM y difracción de rayos X, para observar la morfología de los óxidos. Se realizó la simulación termodinámica del proceso de oxidación en vapor de agua de los substratos para conocer las posibles fases sólidas y gaseosas que se podrían formar, en presencia de una ambiente con 100% vapor de agua y una atmosfera de presión. La forma de ataque a 750 ºC es similar a 700 ºC, aunque la velocidad de oxidación es mayor, ya que la difusión de los elementos de aleación y las reacciones de oxidación son más rápidas. Los recubrimientos de aluminio tienen una buena resistencia a la oxidación en vapor de agua, ya que forman una capa superficial de Al 2 O 3 , que es compacta y adherente, la cual protege al substrato del ataque corrosivo.

  19. Aplicaciones de aluminio mantienen el crecimiento de fresa (Fragaria × ananassa Duch.) suplementada con roca fosfórica en condiciones de cultivo sin suelo

    OpenAIRE

    Martín Alejandro Tucuch Pérez; Armando Hernández Pérez; Luis Alonso Valdez Aguilar; Gloria Alicia Pérez Arias; Juana Cruz García Santiago; Daniela Alvarado Carrillo

    2017-01-01

    Se estima que en los próximos años a nivel mundial habrá carencia de las fuentes de fósforo (P) utilizadas para fabricar los fertilizantes fosforados. Aunque el P puede encontrarse en el suelo, la mayor parte se encuentra en forma no asimilable por las plantas, por lo que para absorberlo éstas exudan ácidos orgánicos (AO) para facilitar su solubilización. Por otro lado, se ha reportado que la presencia de aluminio (Al) se relaciona con un aumento en la exudación de AO por la raíz. Dado la cap...

  20. Mechanical behaviour of AlSiC nano composites produced by ball milling and spark plasma sintering =

    Science.gov (United States)

    Buchheim, Claudia Sofia de Andrade Redondo Murilhas

    Neste trabalho foram produzidos nanocompositos de AlSiC misturando aluminio puro com nano particulas de SiC com diâmetro de 45 - 55 nm, usando, de forma sequencial, a tecnica da metalurgia do po e a compactacao por "Spark Plasma Sintering". O composito obtido apresentava graos com 100 nm de diâmetro, encontrandose as particulas de SiC localizadas, principalmente, nas fronteiras de grao. O nanocomposito sob a forma de provetes cilindricos foi submetido a testes de compressao uniaxial e a testes de nanoindentacao para analisar a influencia das nanoparticulas de SiC, da fracao volumica de acido estearico e do tempo de moagem, nas propriedades mecânicas do material. Para efeitos de comparacao, utilizouse o comportamento mecânico do Al puro processado em condicoes similares e da liga de aluminio AA1050O. A tensao limite de elasticidade do nanocomposito com 1% Vol./Vol. de SiC e dez vezes superior a do AA1050. O refinamento de grao a escala nano constitui o principal mecanismo de aumento de resistencia mecânica. Na realidade, o Al nanocristalino sem reforco de particulas de SiC, apresenta uma tensao limite de elasticidade sete vezes superior a da liga AA1050O. A adicao de 0,5 % Vol./Vol. e de 1 % Vol./Vol. de SiC conduzem, respetivamente, ao aumento da tensao limite de elasticidade em 47 % e 50%. O aumento do tempo de moagem e a adicao de acido estearico ao po durante a moagem conduzem apenas a um pequeno aumento da tensao de escoamento. A dureza do material medida atraves de testes de nanoindentacao confirmaram os dados anteriores. A estabilidade das microestruturas do aluminio puro e do nanocomposito AlSiC, foi testada atraves de recozimento de restauracao realizado as temperaturas de 150 °C e 250 °C durante 2 horas. Aparentemente, o tratamento termico nao influenciou as propriedades mecânicas dos materiais, excepto do nanocomposito com 1 % Vol./Vol. de SiC restaurado a temperatura de 250 °C, para o qual se observou uma reducao da tensao limite de elasticidade

  1. La interacción de materiales del sistema sílice-alúmina con productos fluorados aluminosos

    Directory of Open Access Journals (Sweden)

    Verdeja, L. F.

    1998-05-01

    Full Text Available The aim of this paper is to get a first approximation of the systematic study of the corrosion mechanisms of the silica-alumina, alumina and rich-alumina refractory by fluoride compounds and molten aluminum. The thermodynamic results support the main role of the chemical attack and the erosive mechanisms in the wear of the silica-alumina materials. The influence of the composition of the crystalline phases in the degree of the ceramic lining attack is also studied. The results suggest not to use either oxide or nitride high-value materials for the lining of furnaces and transport recipients containing molten aluminum, because of the chemical corrosion by compounds such as cryolite or aluminum fluoride and also, because of the avidity of aluminum towards oxygen. The study of corundum-based materials like the best refractory used in order to react with fluoride compounds and molten aluminum is an alternative to be considered. The study of the crusts adhesion like a protection mechanism of the refractory lining is also a possible approach.

    Este trabajo pretende contribuir al estudio sistemático de los mecanismos de corrosión que experimentan los refractarios sílico-aluminosos, aluminosos y de alta alúmina con productos fluorados y aluminio en estado líquido. Se aportan datos termodinámicos que confirman el papel preponderante del ataque químico y de los mecanismos erosivos en el desgaste de materiales del sistema sílice-alúmina. Se discute, asimismo, la influencia de la composición de las fases cristalinas encontradas en el grado de agresión a los revestimientos cerámicos. Se propone, ante la agresividad de agentes químicamente activos, como la criolita o el fluoruro de aluminio, y la gran afinidad del aluminio por el oxígeno, no aconsejar la utilización de materiales oxídicos y nitrurados de alto valor para el revestimiento de hornos y bolsas de transporte de aluminio. Se propone, como línea de trabajo a seguir, la

  2. Gel de hidróxido de aluminio: análisis comparativo de métodos de separación sólido-líquido que se utilizan en su producción

    OpenAIRE

    Jesús García Valdés; Martha Gómez Carril

    2000-01-01

    Se analizó de forma comparativa diferentes variantes de separación sólido-líquido para la obtención del gel de hidróxido de aluminio como sedimentación, filtración al vacío (por lotes y continua), filtración a presión y centrifugación. Se presentan las ventajas y desventajas de cada variante incluyendo un análisis técnico-económico de éstas. Se concluye que el uso de un filtro rotatorio al vacío satisface los requerimientos establecidos.Different variants of solid-liquid separation for the ob...

  3. Optimización de diseño de llantas de aluminio a flexión mediante el método de elementos finitos

    OpenAIRE

    Fabio Marcelo Peña Bustos

    2010-01-01

    El presente trabajo da a conocer el proceso llevado a cabo para la optimización del diseño estructural a fatiga por flexión de llantas de aluminio automotrices en una empresa ubicada en la ciudad de Manizales, Colombia. El proceso se efectuó relacionando los análisis de elementos finitos con los resultados de la prueba física de fatiga por flexión, demostrando que el diseño de llantas de aluminio puede optimizarse reduciendo el tiempo de desarrollo de cada modelo, obteniendo llantas más livia...

  4. Caracterización y ensayos de corrosión de aluminio AA2024-T3 recubierto con polianilina como polímero conductor

    OpenAIRE

    Català de Haro, Marc

    2014-01-01

    El presente proyecto estudia las propiedades físicas y químicas de un recubrimiento de polianilina, sobre aluminio AA2024-T3, una aleación de aluminio muy utilizada en la industria, el sector de la aviación y el aeroespacial. La polianilina es un polímero conductor con muchas aplicaciones dentro de los campos tecnológico y biológico, y también actúa como potente protector contra la corrosión. Además, se analizarán los efectos, sobre las propiedades de dicho recubrimiento del Novaclean®, un de...

  5. SÍNTESIS DE ÓXIDOS CONDUCTORES TRANSPARENTES DE ÓXIDO DE ZINC DOPADO CON ALUMINIO POR COPRECIPITACIÓN QUÍMICA

    Directory of Open Access Journals (Sweden)

    Silvia Maioco

    2013-01-01

    Full Text Available Los óxidos de zinc dopados con Al (AZO son promisorios reemplazantes de los óxidos de indio dopados con Sn (ITO pero sus películas delgadas muestran un amplio rango de propiedades fuertemente dependientes de las condiciones del proceso de deposición. Se examinan cerámicos de granulometría submicrométrica de óxido de zinc dopado con 1% de aluminio, preparados por coprecipitación en solución acuosa, a partir de Zn(NO32 y Al(NO33, sinterizados a 1200°C y subsecuentemente templados en atmósfera controlada de 10-16 atm de oxígeno, a 1000°C. La resistividad eléctrica disminuye en dos órdenes de magnitud en las primeras dos horas de templado y el coeficiente Seebeck cambia de -140 a -50 μV/K gradualmente en 8 h. Se concluye que el aumento de la movilidad domina sobre el de densidad de portadores, inducido por cambios de la estequiometria metal oxígeno.

  6. Determinación de aluminio en líquidos concentrados de hemodiálisis por espectrofotometría de absorción atómica

    OpenAIRE

    Rubia Comos, Juan Miguel de la

    2002-01-01

    El aluminio en los líquidos de hemodiálisis supone un importante problema toxicológico cuando se encuentra en concentraciones importantes. Por ello, en el presente trabajo se ha puesto a punto una técnica por espectrofotometría de absorción atómica con el fin de determinar de una forma rápida, exacta y precisa, las cantidades de aluminio que contienen los líquidos concentrados de hemodiálisis. Para ello, se han realizado diversos ensayos conducentes a: 1º,- Optimizar el programa de temperatur...

  7. Interacción entre el aluminio fundido y las fibras de carbono recubiertas con cobre y níquel en materiales compuestos de matriz metálica

    Directory of Open Access Journals (Sweden)

    Ureña, A.

    2004-04-01

    Full Text Available Aluminium Matrix Composites (AMC reinforced with carbon fiber (Cf show good mechanical properties and great capability of autolubrication. However, carbon fibers have poor wetting and react with molten aluminium producing aluminium carbide (Al4C3, that degrades the composite mechanical properties. In order to improve the wetting and to avoid the reaction between Cf and aluminium, the fibers have been coated with a thin layer of Cu and Ni, using an electroless process. AMC have been made using uncoated carbon fibers and Cu or Ni coated ones. The matrix-reinforcement interface has been analysed using SEM / EDX. Nanoindentation mechanical tests have been carried out to evaluate mechanical properties of the matrix-reinforcement interface.

    Los materiales compuestos de matriz de aluminio (AMC reforzados con fibra de C (Cf presentan unas buenas propiedades mecánicas y una gran capacidad de autolubricación. Sin embargo, las fibras de C tienen una pobre mojabilidad y reaccionan con el aluminio fundido formando Al4C3 en la intercara matriz-refuerzo, lo que provoca la degradación de las propiedades mecánicas del material. Para aumentar la mojabilidad y prevenir la reacción, se han recubierto las fibras con una fina capa de Cu o de Ni, utilizando el proceso de “electroless”. Se han fabricado AMC utilizando Cf sin recubrir y recubiertas de Cu o Ni. Se ha estudiado la intercara matriz-refuerzo mediante SEM / EDX y se han realizado ensayos mecánicos de nanoindentación para evaluar las propiedades mecánicas de la intercara matriz-refuerzo.

  8. Suicidio en el embarazo. Fosfuro de aluminio, “la pastilla del maíz”: consideraciones bioéticas

    Directory of Open Access Journals (Sweden)

    L.J. Valderrama Zaldívar

    2015-01-01

    Conclusión: Las autoridades estatales y federales deben reglamentar el uso y venta del fosfuro de aluminio y otros pesticidas. Es necesaria la capacitación del personal de salud sobre temas relacionados con la bioética y la tanatología.

  9. Riesgos a la salud por presencia del aluminio en el agua potable

    OpenAIRE

    Rodolfo Trejo Vázquez; Virginia Hernández Montoya

    2004-01-01

    En la actualidad el aluminio tiene una amplia aplicación en la industria alimenticia, farmacéutica, del papel, de la construcción y en el tratamiento de agua para beber y agua residual. Sin embargo, no se ha dado énfasis a los posibles daños a la salud originados por el consumo de este elemento. Una de las enfermedades que ha sido asociada a la ingesta de este elemento es el Alzheimer y se corre el riesgo de desarrollar otros padecimientos. En el presente documento se ...

  10. Estudio del mecanismo de reacción durante la refinación de magnesio de aleaciones de aluminio líquidas usando partículas de SiO2

    Directory of Open Access Journals (Sweden)

    Flores, A.

    2008-04-01

    Full Text Available An analysis of the results regarding the permanent contact reaction that occurs between the Mg dissolved in molten aluminum and SiO2 particles is presented. The experiments were carried out at constant temperature and molten metal stirring velocity. In the Scanning Electron Microscope, the crystallographic characteristics of the reaction products were determined using the Electron Backscattered Diffraction Technique, thus allowing to establish the stoichiometry and the mechanism of reaction. The results indicate that the mechanism of reaction is governed by Al, Mg, and Si ions diffusion through the layers of reaction products composed of MgAl2O4 and Al2O3 phases. It was found that during the process the composition of the reaction products changed as the concentration of Mg in the boundary layer diminished.

    Se presentan y discuten los resultados de un estudio acerca de la reacción de contacto permanente que ocurre entre partículas de sílice y el magnesio disuelto en una aleación de aluminio líquida, a temperatura y velocidad de agitación constantes. Se obtuvieron muestras en función del tiempo de contacto, siendo caracterizadas mediante Difracción de Electrones Retrodispersados (EBSD en el Microscopio Electrónico de Barrido. Esto, permitió definir la estructura cristalina de los compuestos que se forman durante las reacciones involucradas y como consecuencia determinar la estequiometría y el mecanismo de reacción. Los resultados indicaron que dicho mecanismo está gobernado por la difusión de los iones de aluminio, magnesio y silicio a través de la porosidad de las capas de MgAl2O4 y Al2O3 que se forman como productos de reacción, encontrándose, además, que la composición de dichos productos cambiaba conforme la concentración de magnesio en la interfase sólido (SiO2-fundido (Al-Mg disminuía.

  11. Selecting in vitro of Rhizobiumfor tolerance to acidity and aluminium Selección in vitro de Rhizobium tolerante a acidez y aluminio

    Directory of Open Access Journals (Sweden)

    Campos Segura Ricardo

    1995-12-01

    Full Text Available Fifty strains of Rhizobium tropiciisolated of Sabana de Bogotá soils and foreigns collections were screened for tolerance of acidity and aluminium in liquid and sol id culture. Assesment of visible turbidity and colonies growth, respectively, indicated five
    (5 strains tolerant of pH 4.5 and pH 5.0 and 10 or 20 u M Aluminium. Strains that tolerated the 10 west pH values in culture were tolerant of the highest aluminium concentrations
    The cultural test should be used to predict the ability of Rhizobium to growth and for use as inoculants in low pH area.La apertura económica puso de presente la obligación de revisar las formas de producción de los cultivos comerciales, Con el fin de competir adecuadamente en mercados internacionales. Actualmente, leguminosas, como el frijol (Phaseolus vulgarís se presentan, actualmente, como cultivo alternativo para reemplazar cultivos tradicionales en la Sabana de Bogotá. Existe un alto porcentaje de suelos ácidos en Colombia, así como problemas nutricionales, en los cuales la deficiencia de nitrógeno es muy común. El presente trabajo se realizó con el objetivo de seleccionar "in vitro" cepas de Rizobium tropici tolerantes a acidez y aluminio, en medios de cultivo diferentes. Inicialmente se hizo una preselección "in vitro" de cepas tolerantes a tres niveles de pH 4,0; 4,5 y 5,0, utilizando el medio líquido de Wood y Cooper y usando 50 cepas entre nativas y foráneas. En este caso, se seleccionaron las cepas RC 92, RC 117, C 7, C 11, C 14, C 53, Nifta1182, RC 70, RC 85, CIAT 899, CIAT 144 y Niftal 241. Posteriormente, se realizó una selección "in vitro" de cepas tolerantes a dos niveles de pH: 4,5 y 5,0 y a
    cuatro niveles de aluminio: 0,5; 10 y 20 M, utilizando dos fuentes de aluminio: AlCl3 y ALK(S042 y empleando dos medios de cultivo: el líquido de Wood y Cooper y el sólido de Keyser y Munns. Las cepas RC 85, C 11, CIAT 899, CIAT 144 y Niftal 182, fueron seleccionadas como las de

  12. Corrosión e inhibición en aleaciones de aluminio de media resistencia

    Directory of Open Access Journals (Sweden)

    Davó, B.

    2004-12-01

    Full Text Available The use of chromâtes in aluminum alloys with aeronautical applications has been limited because of the high toxicity of these compounds. This has spurred intensive efforts to develop alternative effective and innocuous inhibitors. In this work, corrosion inhibition of a light and high strength Al-Li-Cu alloy (8090 is studied in NaCl solutions with CeCl3 and LaCl3 lanthanide salts added. The corrosion rate is reduced at least one order of magnitude with concentrations between 100-10,000 ppm. SEM, EDS and XPS techniques are used to characterize the rare earth cations incorporated into the surface as oxides and hydroxides.

    La elevada toxicidad de los cromatos limita cada vez más su uso en los tratamientos superficiales que se aplican a las aleaciones de aluminio en la industria aeronáutica. Por ello, es urgente encontrar inhibidores, no sólo tan eficaces como los cromatos sino, también, inocuos. En este sentido, se ha estudiado la inhibición de la corrosión de una aleación ligera de alta resistencia Al-Li-Cu (8090 en soluciones de NaCl con sales lantánidas de CeCl3 y LaCl3. Se ha comprobado que concentraciones comprendidas entre 100 y 10.000 ppm disminuyen la cinética de corrosión, al menos, un orden de magnitud. La superficie se modifica por la formación de una capa de óxidos e hidróxidos del catión lantánido que se ha caracterizado mediante SEM, EDS y XPS.

  13. Soldadura TIG de espumas de aluminio. Análisis de los parámetros operacionales de espumado

    Directory of Open Access Journals (Sweden)

    Portolés, A.

    2011-06-01

    Full Text Available In this work the influence of main parameters that take part during TIG welding process are analyzed. Some of these parameters belong to the welding process, as for example the welding speed, intensity and voltage while others are from the material and tooling features, as for example foaming material and tooling design. The result of this work shows a strong dependence on these parameters of the TIG welding process for metallic foams.

    En este trabajo se analiza la influencia de los principales parámetros que intervienen en el proceso de soldadura TIG. Algunos de estos parámetros pertenecen al proceso de soldadura, velocidad de soldadura, intensidad y tensión, mientras otros son propios de las características del material y el utillaje, material precursor y forma de implementar la instalación de ensayo. El resultado de este trabajo muestra una fuerte dependencia de estos parámetros con el proceso de soldadura TIG para las espumas metálicas de aluminio.

  14. Alteraciones auditivas en trabajadores expuestos al ruido industrial

    OpenAIRE

    Hernández Díaz, Adel; González Méndez, Bianka M.

    2007-01-01

    Motivados por la importancia del ruido como riesgo laboral en las actividades productivas de la Carpintería de Aluminio "Tomás Alvarez Breto" decidimos realizar un control audiométrico periódico de estos trabajadores con la finalidad de determinar el grado de exposición de los mismos y establecer las recomendaciones más importantes para su protección. Nos propusimos como objetivo determinar el grado de afectación auditiva por ruido en los trabajadores expuestos al riesgo, para lo cual se cuan...

  15. Lixiviación alcalina de las colas de la tecnología carbonato amoniacal para la extracción de aluminio

    Directory of Open Access Journals (Sweden)

    Carmen Hernández-Fernández

    2013-11-01

    Full Text Available Se estudió la termodinámica del proceso de lixiviación alcalina de las colas derivadas del proceso carbonato amoniacal para conocer la espontaneidad de las reacciones y comprobar la posibilidad de extracción del aluminio utilizando como agente lixiviante el hidróxido de sodio (NaOH. Las colas, una vez caracterizadas químicamente, se lixiviaron a escala de laboratorio aplicando un diseño experimental factorial completo. La variación de energía libre indica que es posible extraer aluminio de las colas, lixiviándolas con hidróxido de sodio; para un 45 % de sólido las mayores extracciones se obtienen a 200 ˚C y 30 min. El silicio y el magnesio también mostraron selectividad con el reactivo utilizado

  16. Evaluación de la eficacia de fungicidas aplicados al suelo y al follaje

    Directory of Open Access Journals (Sweden)

    Quiroga B. Nini Johanna

    2004-12-01

    Full Text Available

    Una de las enfermedades más limitantes en los cultivos de rosa colombianos para exportación es el mildeo velloso, producido por Peronospora sparsa. Dentro de las herramientas más utilizadas para el manejo de la enfermedad es la aplicación de fungicidas, pero poco se conoce sobre su eficacia y la forma de aplicación más efectiva. El objetivo de la investigación fue evaluar la eficacia de las aplicaciones foliares y en aspersión al suelo (“drench” de los fungicidas dimetomorf, fosetil de aluminio y metalaxil+mancozeb, en comparació con un testigo comercial. El diseñ utilizado fue completamente al azar con nueve tratamientos y tres repeticiones. La incidencia y la severidad de la enfermedad fueron evaluadas en las hojas de los estratos inferior, medio y superior de los tallos y se encontraron diferencias significativas entre los tratamientos, asícomo para la incidencia en tallos y botones florales. Las aplicaciones foliares de los fungicidas mostraron un mayor control de la enfermedad. El control más eficaz se obtuvo con fosetil de aluminio aplicado al follaje. Los tratamientos

  17. Obtención por vía pulvimetalúrgica de materiales compuestos de matriz de aluminio reforzados con nitruros

    Directory of Open Access Journals (Sweden)

    Fogagnolo, J. B.

    2000-08-01

    Full Text Available The use of aluminium metal matrix composites as structural materials is increasing continuously, mainly in the automotive and aerospace industries. The development of new kind of reinforcements is one of the areas of greater interest in current researches. This work investigates the use of nitrides as reinforcement for composite materials, with Al 6061 matrix, obtained by powder metallurgy and extrusion, presenting their microstructural features and their mechanical characteristics.

    La utilización de los materiales compuestos de matriz de aluminio como materiales estructurales está en continuo crecimiento principalmente en la industria automovilística y aeroespacial. El desarrollo de nuevos tipos de refuerzos es una de las áreas de mayor interés en las más actuales investigaciones. Este trabajo investiga el uso de nitruros como refuerzo en materiales compuestos, de matriz de aleación AA6061, obtenidos vía pulvimetalúrgica y extrusión, presentando los aspectos microestruturales y las características mecánicas.

  18. Comportamiento térmico de aleaciones de aluminio de la serie 2XXX sinterizadas : estudio de la influencia de la aleación mecánica y adiciones de SN y TICN

    OpenAIRE

    Santos Sánchez, Enrique

    2011-01-01

    Las principales propiedades que hacen del aluminio un material atractivo son su baja densidad, su buena resistencia mecánica específica, su ductilidad y su elevada resistencia a la corrosión. Debido a la combinación única de estas propiedades, los materiales base aluminio están cada vez más integrados y demandados en la sociedad actual. Las propiedades termomecánicas de los metales y sus aleaciones se pueden mejorar mediante la utilización de diversos tipos de refuerzos; pueden ser fibras de ...

  19. Obtención de microestructuras de grano ultrafino en aleaciones de aluminio mediante extrusión en canal angular (ECAE

    Directory of Open Access Journals (Sweden)

    Alkorta, J.

    2004-04-01

    Full Text Available Al 5083 samples have been subjected to 90º equal-channel angular extrusion (ECAE at 270ºC. After ECAE, the microhardness was measured and the texture for the plane perpendicular to the extrusion direction was analysed by X-Rays and EBSD. The microstructure was characterized by optical microscopy and EBSD. As deformation accumulates the hardness increases until it reaches saturation at an effective strain of about ε∼4. With regard to the texture, it has been shown that a high density of {111} planes are oriented parallel to the shear plane of the last pass.

    Varias muestras de aluminio 5083 se han sometido a extrusiones en canal angular de 90º a 270ºC. A continuación se midieron las durezas de las muestras obtenidas y se caracterizó la textura en el plano perpendicular a la dirección de extrusión mediante Rayos-X y difracción de electrones retrodispersados (EBSD. La caracterización microestructural se hizo mediante microscopio óptico y EBSD. Se ha observado que la dureza aumenta sensiblemente con el grado de deformación y que alcanza un nivel máximo de saturación a partir de ε∼4. En cuanto a la textura, se observa que los planos {111} tienden a orientarse paralelos al plano de la última cortadura.

  20. Soldadura de aleaciones de aluminio con láseres de Nd:YAG de alta potencia

    Directory of Open Access Journals (Sweden)

    García Orza, J. A.

    1998-04-01

    Full Text Available Aluminium alloys have good mechanical properties (high strength-to-weight ratio, corrosion resistance and good workability. Their applications are growing up, specially in the transportation industry. Weldability is however poorer than in other materials; recent advances in high power YAG lasers are the key to obtain good appearance welds and higher penetration, at industrial production rates. Results of the combination of high power YAG beams with small fiber diameters and specific filler wires are presented. It is also characterized the airborne particulated material, by-product of the laser process: emission rates, size distribution and chemical composition are given for several aluminium alloys.

    El uso del Al y sus aleaciones es creciente en la fabricación de vehículos de transporte. Su soldabilidad es menor que la de otros materiales y las aleaciones presentan cierta disminución de propiedades por pérdida de aleantes y/o de su tratamiento térmico. Se revisa brevemente el uso de láseres de Nd:YAG de potencia en soldeo de aleaciones de aluminio y se presentan resultados de la combinación de haces de potencia guiados por fibras de pequeño diámetro, con focos ligeramente superpuestos en la pieza. Finalmente, se caracterizan los humos producidos en la soldadura con láser continuo de 2 kW.

  1. Gel de hidróxido de aluminio: análisis comparativo de métodos de separación sólido-líquido que se utilizan en su producción

    Directory of Open Access Journals (Sweden)

    Jesús García Valdés

    2000-08-01

    Full Text Available Se analizó de forma comparativa diferentes variantes de separación sólido-líquido para la obtención del gel de hidróxido de aluminio como sedimentación, filtración al vacío (por lotes y continua, filtración a presión y centrifugación. Se presentan las ventajas y desventajas de cada variante incluyendo un análisis técnico-económico de éstas. Se concluye que el uso de un filtro rotatorio al vacío satisface los requerimientos establecidos.Different variants of solid-liquid separation for the obtention of aluminum hydroxide, such as sedimentation, vacuum filtration (by lots and continual, pressure filtration and centrifugation were comparatively analyzed. The advantages and disadvantages of each variant, including a technical and economic analysis, were presented. It was concluded that the use of a vacuum rotary filter meets the established requirements.

  2. Comportamiento a la corrosión electroquímica de aleaciones MgAl con recubrimientos de materiales compuestos Al/SiCp mediante proyección térmica

    Directory of Open Access Journals (Sweden)

    Pardo, A.

    2010-04-01

    Full Text Available The corrosion protection of Mg-Al alloys by flame thermal spraying of Al/SiCp composite coatings was evaluated by electrochemical impedance spectroscopy in 3.5 wt.% NaCl solution. The volume fraction of SiC particles (SiCp varied between 5 and 30%. The as-sprayed Al/SiCp composite coatings revealed a high number of micro-channels, largely in the vicinity of the SiC particles, that facilitated the penetration of the electrolyte and the subsequent galvanic corrosion of the magnesium substrates. The application of a cold-pressing post-treatment reduced the degree of porosity of the coatings and improved the bonding at the coating/substrate and Al/SiC interfaces. This resulted in improved corrosion resistance of the coated specimens. The effectiveness of the coatings slightly decreased with the addition of 5-30 vol.% SiCp compared with the unreinforced thermal spray aluminium coatings.

    Se estudia, mediante espectroscopía de impedancia electroquímica en solución 3,5 % NaCl, la protección frente a la corrosión de aleaciones Mg-Al recubiertas por proyección térmica con materiales compuestos Al/SiCp. Se varió la fracción de volumen de las partículas de SiC (SiCp entre 5 y 30 %. Los recubrimientos efectuados por proyección térmica revelan un elevado número de microcanales, en la vecindad de las partículas de SiC, que facilitan la penetración del electrolito originando procesos de corrosión galvánica en los substratos de las aleaciones de magnesio. Un tratamiento posterior mediante la aplicación de una presión en frío reduce el grado de porosidad de los recubrimientos y mejora la unión, tanto entre el substrato y el recubrimiento como entre las partículas de aluminio y SiC, mejorando la resistencia a la corrosión de las aleaciones recubiertas. La efectividad de los recubrimientos disminuye ligeramente con la adición de SiCp cuando se comparan con los mismos recubrimientos de aluminio sin refuerzo.

  3. Determinación de los parámetros de corrosión y desgaste del par acero/aluminio en presencia de líquidos iónicos

    OpenAIRE

    Jerez Mesa, Ramón

    2008-01-01

    El presente proyecto presenta resultados obtenidos en ensayos utilizando LI combinados con aluminio 2011 y acero F-1310, tanto en ensayos de corrosión como de tribología. Escuela Técnica Superior de Ingeniería Industrial

  4. La electrocoagulación, una alternativa al proceso convencional de coagulación de aguas residuales

    OpenAIRE

    Cañizares, Pablo; Martínez, Fabiola; Sáez, Cristina; Rodrigo, Manuel

    2009-01-01

    El tratamiento de residuos consistentes en dispersiones acuosas coloidales, o en emulsiones de aceite en agua, se suele realizar mediante la adición de reactivos al residuo, normalmente disoluciones que contienen sales de hierro y aluminio. Una alternativa a la dosificación de estas disoluciones es la generación por vía electroquímica de los iones necesarios para desestabilizar los coloides de la dispersión, o las microgotas de la emulsión, mediante la utilización de planchas de hierro o alum...

  5. Aplicaciones de aluminio mantienen el crecimiento de fresa (Fragaria × ananassa Duch. suplementada con roca fosfórica en condiciones de cultivo sin suelo

    Directory of Open Access Journals (Sweden)

    Martín Alejandro Tucuch Pérez

    2017-07-01

    Full Text Available Se estima que en los próximos años a nivel mundial habrá carencia de las fuentes de fósforo (P utilizadas para fabricar los fertilizantes fosforados. Aunque el P puede encontrarse en el suelo, la mayor parte se encuentra en forma no asimilable por las plantas, por lo que para absorberlo éstas exudan ácidos orgánicos (AO para facilitar su solubilización. Por otro lado, se ha reportado que la presencia de aluminio (Al se relaciona con un aumento en la exudación de AO por la raíz. Dado la capacidad solubilizadora de los AO, en el presente estudio se planteó evaluar el efecto de la aplicación de Al sobre la exudación de AO y el uso de P en forma no soluble (roca fosfórica, RF en el crecimiento y rendimiento de plantas de fresa. El experimento constó de ocho tratamientos que resultaron de combinar dos cantidades de RF, mezcladas en el sustrato, con aplicaciones de Al. Los tratamientos con RF se irrigaron con una solución que contenía 0.25 meq L‑1 H2PO4‑. Los resultados mostraron que con aplicaciones de Al vía riego se obtienen mayores rendimientos, hasta 380 g planta-1, lo cual estuvo correlacionado positivamente con la concentración de ácido cítrico y negativamente con la concentración de ácido málico en el sustrato. Se concluye que el citrato exudado por la raíz debido a la aplicación de Al, favorece el rendimiento de plantas de fresa cuando el P se encuentra en forma de RF.

  6. Hidro conversión de heptano sobre una bentonita colombiana y una saponita española pilarizadas con aluminio y activadas con ácido

    Directory of Open Access Journals (Sweden)

    Manuel Fredy Molina C.

    2011-03-01

    Full Text Available El presente trabajo estudia una arcilla tipo esmectita, una bentonita colombiana, la cual fue sometida a modificación por pilarización con especies de aluminio, y a modificación por tratamiento con ácido clorhídrico de diferentes concentraciones. Igualmente, se empleó una saponita española modificada por pilarización con Al y tratada con ácido clorhídrico de diferentes concentraciones, con el objetode establecer un paralelo entre los dos tipos de arcillas en su comportamiento frente a las modificaciones estudiadas.Los sólidos fueron caracterizados por técnicas convencionales, tales como análisis químico, capacidad de intercambio catiónico, difracción de rayos X, acidez total y análisis de textura. Los resultados indican que los dos tipos dearcilla fueron igualmente pilarizados con Al, independientemente del origen de la esmectita de partida.Los resultados catalíticos en la hidroconversión de heptano, obtenidos sobre catalizadores bifuncionales (arcilla modificada impregnada con Pt revelan que la AlP-saponita es más eficiente en la isomerización que la AIP-bentonita. Esta mayor eficiencia es atribuida a la presencia de sitios ácidos fuertes tipo Si-OH ... Al, los cuales están presentes únicamente en las esmectitas, donde las sustituciones isomórficas están localizadas en las láminas tetraédricas. En montmorillonitas (bentonita, estas sustituciones se encuentran presentes en las láminas octaédricas, de manera que este tipo de sitios ácidos son reducidos o simplemente están ausentes.

  7. Efecto de los aditivos en la formación y estabilidad térmica a baja temperatura del titanato de aluminio

    Directory of Open Access Journals (Sweden)

    Barrios de Arenas, I.

    2000-12-01

    Full Text Available This work presents the study of the effect of 3 wt% V2O5, Na2O, CaO and FeTiO3 on the stabilization of Aluminum Titanate (Al2TiO5. Samples were prepared by the conventional processing route of dry ball milling followed by wet mixing and final uniaxial pressing at 300 MPa before sintering at 1400ºC. Specimens were heat treated at 1000ºC during 12 and 20 hours in order to evaluate Al2TiO5 decomposition. The microstructure was observed by Scanning Electron Microscopy (SEM and phases present were determined by X Ray Diffraction (XRD and Energy Dispersive Spectroscopy (EDS. It has been elucidated the effect of FeTiO3 (Ilmenite on the improvement of the formation and thermal stabilization of Al2TiO5.

    En este trabajo se presenta el estudio del efecto de la adición de 3% en peso de V2O5, Na2O, CaO y FeTiO3 en la estabilización térmica del Titanato de Aluminio (Al2TiO5. El procesamiento de las muestras fue mediante la molienda en seco de los polvos de alúmina y titania, mezcla vía húmeda con alcohol isopropílico y sinterización a 1400ºC de los compactos prensados uniaxialmente a 300 MPa. Una vez sinterizadas las muestras fueron tratadas térmicamente a 1000ºC durante 12 y 20 horas para evaluar la descomposición del Al2TiO5. La microestructura de las probetas se analizó mediante Microscopía Electrónica de Barrido (MEB y las fases presentes se determinaron mediante Difracción de Rayos X (DRX y Espectroscopía de Rayos X por dispersión de Energía (EDX. Esta caracterización evidenció el efecto beneficioso de la adición de FeTiO3 (Ilmenita en la formación y estabilización térmica del Al2TiO5.

  8. The role anions on the synthesis of AlOOH nanoparticles using simple solvothermal method

    Directory of Open Access Journals (Sweden)

    Mozaffar Abdollahifar

    2018-03-01

    Full Text Available Effect of aluminium salts on the synthesis of AlOOH nanostructures has been successfully investigated in detail using solvothermal method, when ethanol and NaOH are solvent and pH adjusting agent, respectively. Fourier transform infrared spectroscopy (FTIR, X-ray powder diffraction (XRD, and field emission scanning electron microscopy (FESEM, were used to characterize the synthesized samples. The specific surface area, pore size distribution and pore structure of the different AlOOH structures were also discussed by the N2 adsorption/desorption test. According to our experimental results, the structure characterization revealed that for synthesized AlOOH nanostructures no obvious XRD peaks arising from other phases of alumina are found indicating pure AlOOH phase of products. Furthermore, the nitrogen adsorption and desorption measurements indicated that the obtained AlOOH nanoparticles from aluminium chloride at basic condition possess a high BET surface area of approximately 90 m2/g. Resumen: El efecto de las sales de aluminio sobre la síntesis de las nanoestructuras de AlOOH ha sido analizado en detalle satisfactoriamente usando el método solvotérmico, cuando el etanol y el NaOH son el disolvente y el agente de regulación del pH, respectivamente. Para clasificar las muestras sintetizadas se utilizaron la espectroscopia infrarroja por transformada de Fourier (FTIR, difracción de rayos X por polvo (XRD y microscopia electrónica de barrido de emisión de campo (FESEM. El área superficial específica, la distribución del tamaño del poro y la estructura de poros de las diferentes estructuras de AlOOH también se debatieron mediante la prueba de adsorción/desorción de N2. De acuerdo con nuestros resultados experimentales, la clasificación de la estructura reveló que en las nanoestructuras de AlOOH sintetizadas no se observan picos XRD evidentes derivados de otras fases de la alúmina que indican la fase pura de AlOOH de los productos

  9. Valoración de los principales parámetros que definen la calidad de las superficies anodizadas en piezas de aluminio para la construcción. // Evaluation of anodized surfaces main parameters that define quality of aluminum parts.

    Directory of Open Access Journals (Sweden)

    J. A. Pérez García

    2004-01-01

    Full Text Available Actualmente en la construcción de edificaciones se utiliza profusamente el aluminio en puertas, ventanas, pasamanos, etc.Con el objetivo de mejorar los parámetros que caracterizan sus cualidades estéticas y de resistencia a la corrosión, estosartículos son sometidos al proceso de anodizado. De todos los factores que intervienen en este proceso, se ha llegado aconocer que hay tres que tienen mayor relevancia en la obtención de la calidad deseada en las piezas: tratamiento previo dela superficie a anodizar, color a aplicar y espesor de la capa de recubrimiento. Este trabajo ofrece, sobre la base deexperimentos llevados a cabo, las relaciones cualitativas entre estos factores y los parámetros que caracterizan la calidaddesde el punto de vista estético (brillo, aspecto, textura y de su resistencia a la corrosión.Palabras claves: Aluminio, anodizado, calidad.__________________________________________________________________________Abstract.Aluminum articles such as windows and doors, etc are widely applied in modern building construction. In order to upgradeaesthetic and corrosion resistant properties of these articles the anodizing process is frequently used. Among all factors thatare involved in this process, there are three having high relevance in order to obtain the desired quality of the final product:previous surface treatment (before anodizing, color of the final article and anodized layers thickness. This paper offers thequalitative relationships between these factors and parameters characterizing corrosion resistance properties and aesthetics.Key words: Aluminun, anodize, quality.

  10. Efecto de la estequiometría y de la temperatura de cocción en el desarrollo de la fase Al2TiO5

    Directory of Open Access Journals (Sweden)

    Baptista, J.

    2003-04-01

    Full Text Available Aluminum Titanate (Al2TiO5 due to its low termal expansion coefficient, low wettability and high refractoriness is a promissing refractory ceramic to be in contact with non ferrous metals, specially molten aluminum. Controlled amounts of CaO, SiO2, MgO and ZrO2 are normally added in order to avoid expontaneous decomposition, lower than 1300°C, into its constituint oxides. In this work through the adoption of a new approach, it was investigated the Al2TiO5 phase development and stabilization with respect to stoichiometry and firing temperature. It was found that an excess of Titania (TiO2 helps the development of a stable and purer Aluminum Titanate phase.El Titanato de Aluminio (Al2TiO5 debido a su bajo coeficiente de expansión térmica, elevada refractariedad y baja mojabilidad por metales no ferrosos fundidos, es un material prometedor en la industria del Aluminio para aplicaciones donde se exige contacto con el baño metálico. Aditivos como CaO, SiO2, MgO y ZrO2 son necesarios para evitar la descomposición espontánea del Al2TiO5 en sus óxidos constituyentes a temperaturas inferiores a 1300°C. En este trabajo, se ha investigado el efecto de la estequiometría y de la temperatura de sinterización en el desarrollo y estabilidad de la fase Al2TiO5. Se ha encontrado que un exceso de Óxido de Titanio (TiO2 es beneficioso en la producción de Al2TiO5 puro y estable.

  11. Diseño de un Sistema de Gestión de Calidad ISO 9001-2008 Empresa Distribuidora de Aluminio y Vidrio

    OpenAIRE

    Espol; Barrera Luces, Jimmy Iván

    2017-01-01

    El objetivo de la presente tesis es diseñar un Sistema de Gestión de Calidad basado en la Norma ISO 9001:2008 que permita asegurar la calidad de los procesos de una empresa de distribución de aluminio y vidrio, ofrecer un método controlado a la administración para cumplir con sus objetivos, beneficiar a la empresa y a los clientes. Guayaquil MAGÍSTER EN GESTIÓN DE LA PRODUCTIVIDAD Y CALIDAD

  12. SIMBIOSIS MICORRIZICA ARBUSCULAR Y ACUMULACIÓN DE ALUMINIO EN Brachiaria decumbens Y Manihot esculenta SIMBIOSE MICORRIZICA ARBUSCULAR E ACUMULAÇÃO DE ALUMÍNIO EM Brachiaria decumbens E Manihot esculenta ARBUSCULAR MYCORRHIZAL SYMBIOSIS AND ACUMULATION OF ALUMINUM Brachiaria decumbens AND Manihot esculenta

    Directory of Open Access Journals (Sweden)

    BEATRIZ ELENA GUERRA S.

    2012-12-01

    Full Text Available Suelos dedicados al monocultivo de Elaeis guineensis Jacq en Puerto Wilches-Santander-Colombia, presentan baja fertilidad, altas saturaciones de aluminio y baja densidad de esporas de hongos micorrizicos. Se evaluó el comportamiento de la simbiosis micorrizica utilizando suelos nativos con micorrizas (MA+ y sin micorrizas (MA-, en Brachiaria decumbens y Manihot esculenta, quienes poseen alta micotrofia y capacidad de retención del ión aluminio. Se consideraron las variables densidad de esporas, porcentaje de colonización micorrizica, biomasa seca y longitud radicular, concentración de aluminio foliar y radicular. Se realizó una (ANOVA de dos vías con un modelo lineal general. Se observaron porcentajes de colonización micorrizica superiores al 70% en B. decumbens en suelos con concentraciones de 0,6 y 1,4 meq/100 g de Aluminio. M. esculenta presento 50 % de simbiosis micorrizica, en todos los tipos de suelo. Se incrementaron las esporas nativas de palma aceitera hasta un 200% en las dos plantas huespéd. Las concentraciones de aluminio a nivel radicular fueron mayores en plantas micorrizadas, mientras que a nivel foliar los valores fueron más bajos.Solos dedicados à monocultura de Elaeis guineensis Jacq em Puerto Wilches-Santander apresentam baixa fertilidade, alta saturação de alumínio e baixa densidade de esporos de fungos micorrízicos. Avaliaram-se o comportamento da simbiose micorrízica usando solos nativos com fungos micorrízicos (MA+ e sem fungos micorrízicos (MA-, na Brachiaria decumbens e Manihot esculenta, plantas com alto grau de micotrofia e capacidade de retenção de íons de alumínio. Considerou-se as variáveis: densidade de esporos, porcentagem de colonização micorrízica, biomassa seca, longo da raiz e concentração de alumínio nas folhas e raízes. Realizou-se uma (ANOVA de duas vias com o modelo linear geral. Observou-se porcentagens de colonização micorrízica acima de 70% na B. decumbens em solos com

  13. Regeneración ósea guiada utilizando membrana de óxido de aluminio en combinación con implantes oseointegrados Guided bone regeneration using aluminum oxide membrane in combination with osseointegrated implants

    Directory of Open Access Journals (Sweden)

    M. Isa Majluf

    2007-08-01

    Full Text Available La reabsorción ósea de los maxilares ha sido una de las mayores complicaciones al momento de rehabilitar a pacientes con implantes oseointegrados. El siguiente estudio evaluó la efectividad de la membrana de óxido de aluminio (alúmina, en la regeneración ósea de rebordes colapsados y alvéolos en los que se colocaron implantes. De un total de cinco pacientes seleccionados, se estudiaron siete sitios de los cuales tres correspondieron a un solo paciente. En cada sitio (alvéolo o reborde colapsado se colocó un implante de titanio del sistema HIS y una membrana no biodegradable de óxido de aluminio (Allumina®, la cual fue retirada a las 14 semanas. Todos los pacientes fueron sometidos al mismo procedimiento quirúrgico. La ganancia promedio en mm obtenidos en orden decreciente fue la siguiente: ANM: 1.7mm, ANME: 1.6mm, AND: 1.1mm, AV: 1.0mm, AP: 0.5mm. Los resultados radiográficos ratificaron los resultados clínicos en cuanto a neoformación ósea, observándose además una favorable densidad ósea periimplantaria. El análisis estadístico (basado en los resultados clínicos t-student fue significativo para todos los parámetros evaluados con excepción de AP.Alveolar bone loss has been a very important cause of complications in osseointegrated implant rehabilitation of edentulous patients. This paper evaluates the effectiveness of aluminum oxide membrane (Allumina in the collapsed alveolar ridge where implants were used. Seven sites were studied in 5 patients. In each of these sites a HIS implant plus a non-biodegradable oxide aluminum membrane (Allumina®, was placed for 14 weeks. All patients were treated with the same surgical protocol. The average gain (in mm obtained in decreasing order was as follows: ANM: 1.7 mm, ANME: 1.6 mm, AND: 1.1mm, AV: 1.0mm, AP: 0.5mm. The clinical results were radiographically verified and these showed bone neoformation, in addition to favorable peri-implant bone density. The t-Student statistical

  14. Desempeño ante la corrosión y tribocorrosión de aleaciones comerciales de aluminio anodizadas

    OpenAIRE

    Rodríguez, Samantha; Carrasquero, Edwuin J.; López, Luis M.; Fajardo, Jorge I.

    2016-01-01

    El presente trabajo muestra la evaluación del desempeño de dos aleaciones comerciales de aluminio anodizadas ante la corrosión y tribocorrosión. Para el anodizado se emplearon dos tipos de electrolitos distintos (H2SO4 y H2C2O4), un valor constante de densidad de corriente y dos tiempos de anodizado (30 y 45 minutos). Usando una de las técnicas de microscopía electrónica de barrido (MEB) y espectroscopía por dispersión de la energía de rayos X (EDX) se caracterizaro...

  15. Fluidos iónicos en lubricación de contactos aluminio-acero : interacciones superficiales y triboquímicas

    OpenAIRE

    Jiménez Ballesta, Ana Eva

    2009-01-01

    Los líquidos iónicos (LI) son fluidos de altas prestaciones con un amplio rango de estabilidad térmica. Actualmente están siendo objeto de estudio en una gran variedad de contactos, siendo una de sus aplicaciones tribológicas más interesante la lubricación del contacto aluminio-acero. En este trabajo se estudia la influencia de la longitud de la cadena lateral del catión y de la naturaleza del anión sobre la capacidad lubricante de 6 LI derivados del catión imidazolio, un derivado de piridini...

  16. Electrodissolution aluminum electrode during an electrocoagulation acid whey

    Directory of Open Access Journals (Sweden)

    Francisco Prieto-García

    2014-01-01

    Full Text Available La electrodisolución de aluminio en soluciones conteniendo ione s cloruros o sulfatos durante el proceso de electrocoagulación del lactosuero ácido, ha sido el objetivo de este trabajo. Los pH alcalinos aumentan la velocidad de disolución en varios órdenes de magnitud. El me dio electrolítico (Cl - o SO 4 2- no parece influir significativamente en la disolución de alum inio, pero aumentan la densidad de carga, que ayuda en el proce so electroquímico. Los resultados están relacionados con la natura leza de las especies de hidróxidos de aluminio formados durante la disolución anódica. En condiciones ácidas y neutras, los iones OH - del cátodo no participan completamente en la formación de espe cies neutras de hidróxido de aluminio y el exceso de iones OH - aumenta el pH del medio. En contraste, el pH disminuye en cond iciones altamente alcalinas atribuido al consumo de grandes cantidades de iones OH - para formar especies aniónicas, tales como Al(OH 4 - y Al(OH 5 2- y otras especies oligoméricas de aluminio.

  17. Optimización de diseño de llantas de aluminio a flexión mediante el método de elementos finitos

    Directory of Open Access Journals (Sweden)

    Fabio Marcelo Peña Bustos

    2010-01-01

    Full Text Available El presente trabajo da a conocer el proceso llevado a cabo para la optimización del diseño estructural a fatiga por flexión de llantas de aluminio automotrices en una empresa ubicada en la ciudad de Manizales, Colombia. El proceso se efectuó relacionando los análisis de elementos finitos con los resultados de la prueba física de fatiga por flexión, demostrando que el diseño de llantas de aluminio puede optimizarse reduciendo el tiempo de desarrollo de cada modelo, obteniendo llantas más livianas, lo cual significa ahorro en costos de desarrollo y manufactura del producto con las consecuentes mejoras de eficiencia y desempeño de los vehículos. Además, la incorporación temprana de la simulación el proceso de desarrollo del producto da como resultado diseños que pueden optimizarse antes de fabricar y ensayar los prototipos físicos. El trabajo presentado da a conocer entonces, cómo se ha incorporado exitosamente el análisis de elementos finitos como parte del proceso normal de diseño de llantas de la empresa objeto de estudio, con los consecuentes beneficios en términos de confiabilidad y productividad.

  18. INDUSTRIA, EMISIONES GASEOSAS Y GESTIÓN AMBIENTAL URBANA Diagnóstico de las condiciones operativas de las fundiciones en Tandil, Argentina

    Directory of Open Access Journals (Sweden)

    Beatriz Soledad Sosa

    2013-06-01

    Full Text Available De las problemáticas ambientales urbanas, las asociadas a la industria presentan especial interés para la gestión ambiental. La ciudad de Tandil en Argentina, debe su crecimiento económico y urbano a la actividad metalmecánica, -en particular a la fundición-, y a pesar de las crisis del sector, la actividad sigue siendo eje de crecimiento económico y urbano local. Esta investigación caracteriza -en términos productivos, operativos y ambientales- las industrias de fundición y evalúa las condiciones operativas de la gestión de emisiones gaseosas en el sector en el año 2010. Fue posible analizar unas 25 industrias sobre 30. La muestra fue representativa de los cinco procesos productivos identificados: aluminio (Al, aluminio/hierro (Al Fe, aluminio/bronce (Al Cu+Sn, aluminio/hierro/bronce (Al Fe Cu+Sn, hierro (Fe. Las variables analizadas fueron: materia prima de fusión, horno utilizado y, tamaño de la industria. Para la obtención de los datos de producción se aplicaron entrevistas estructuradas, y para determinar el tamaño de la industria  se usaron encuestas. Fue posible describir la situación productiva del sector a nivel local: La mayoría de las industrias destinan su producción al sector automotriz. Evaluando la relación tamaño y tipo de empresa, las fundiciones de Aluminio son pequeñas. En relación al hierro, están representados los tres tamaños empresariales posibles y existe una industria mediana que ocupa entre 51 y 230 empleados. Las condiciones operativas y de cumplimiento de la legislación en el control de los efluentes gaseosos analizados demandan identificar indicadores de seguimiento para la etapa de fusión del proceso para conocer con precisión los contaminantes resultantes y sus efectos ambientales.   

  19. Soldadura TIG y MIG de las aleaciones de aluminio 6061 y 7020. Estudios microestructurales y de propiedades mecánicas

    Directory of Open Access Journals (Sweden)

    Gómez de Salazar, J. M.

    1998-05-01

    Full Text Available The aluminium alloys of the 6XXX and 7XXX series, are actually considered of medium and high strength, and are been profusely used in different industries such as aeronautical, automotive, etc. However, its wide application as structural material needs of the proper development of their joining process. The present work describes the results obtained from the microstructural evaluation, both with optical and scanning electronic microscopies (OM and SEM, and of the mechanical one (hardness changes of the weld produced in the alloys using two different are welding techniques: GTAW (TIG and GMAW (MIG. For the last one, a filler metal with a composition of Al-5Mg, AWS denomination A5.10-92 (AA5356, has been used.

    Las aleaciones de las series AA6XXX y AA7XXX están consideradas como de media y alta resistencia, y se utilizan con gran profusión en tecnologías como: aeronáutica, automoción, etc. Pero su aplicación como materiales estructurales pasa, sin duda, por el adecuado desarrollo de sus procesos de unión. En este trabajo, se realiza una evaluación microestructural, tanto mediante técnicas de microscopía óptica (MO como electrónica (MEB-EDS y de las propiedades mecánicas (evolución de la dureza de estas aleaciones, una vez que han sido sometidas a procesos de soldadura con arco, como son GTAW (TIG y GMAW (MIG, empleando un aporte de aleación de aluminio de composición Al-5Mg, cuya denominación es AWS A5.10-92 (AA5356.

  20. Lubricación del contacto aluminio-acero con líquidos iónicos en atmósfera controlada

    OpenAIRE

    Llopis Morales, Miguel

    2016-01-01

    El objetivo del presente proyecto es estudiar el comportamiento tribológico de diferentes líquidos iónicos en el contacto aluminio-acero y las interacciones superficiales que se producen. Para realizar el estudio tribológico, se llevará a cabo un estudio de corrosión previo por lo que será necesario realizar ensayos de corrosión y tribológicos. En cuanto a los objetivos de los ensayos de corrosión, el objetivo que se quiere alcanzar con este ensayo es comprobar si se produce algún tipo de cor...

  1. Nuevos adyuvantes en la inmunoterapia específica de las enfermedades alérgicas: estudio de aspectos inmunológicos, celulares y repercusión funcional respiratoria en un modelo animal de asma bronquial

    OpenAIRE

    Vázquez de la Torre Gaspar, María, María

    2015-01-01

    INTRODUCCIÓN: Las sales de aluminio se vienen utilizando tradicionalmente, como adyuvante de la ITE s.c. convencional. La identificación de adyuvantes alternativos que indujeran una respuesta Th1 y T reguladora, mejoraría la eficacia de la ITE como tratamiento para el asma y otras enfermedades alérgicas. OBJETIVOS: El objetivo general de este proyecto es la comparación de la eficacia, clínica e inmunológica, de diferentes adyuvantes para inmunoterapia específica de las enfermedades alérgicas...

  2. Simplificación del procesado de polvo de aluminio molido y estudio de las propiedades mecánicas de los compactos resultantes

    Directory of Open Access Journals (Sweden)

    Cintas, J.

    2001-04-01

    Full Text Available An alternative powder-metallurgy consolidation method of milled aluminium (M Al powder, consisting in a double cycle of cold pressing and vacuum sintering, has been developed. The aim of the present investigation is to simplify this consolidation method, from the original five steps to only three steps. This would be possible since milled powders soften during desassing, at high temperature. The mechanical properties of compacts (hardness at room and high temperature, ultimate tensile strength and elongation obtained by the three-step and the five-step processing are comparable. This process could be of special interest for the manufacturing of large series of small parts, such as are used in the automotive industry.

    Se ha desarrollado un nuevo método de consolidación pulvimetalúrgica de aluminio molido consistente en una desgasificación seguida de un doble ciclo de prensado y sinterización. El objetivo principal de este trabajo es reducir las anteriores 5 etapas de consolidación a sólo 3, valiéndose del reblandecimiento que sufre el polvo al desgasificarlo a temperatura elevada. Según los resultados obtenidos, las propiedades mecánicas de los compactos finales (dureza, resistencia a la tracción, alargamiento y dureza en caliente son comparables a las obtenidas por ciclo doble. Esta vía de consolidación puede ser de interés para la fabricación de grandes series de piezas pequeñas, como son típicas en la industria del automóvil.

  3. Análisis de falla en evaporadores de placas de aluminio de sistemas de acondicionamiento de aire automotriz

    Directory of Open Access Journals (Sweden)

    Santiago Mendoza Hurtado

    2011-01-01

    Full Text Available Se caracterizaron los tipos de fallas a partir del estudio de tres perfiles de evaporadores de placas de aleación de aluminio, puestos fuera de servicio por fugas del refrigerante y obtenidos en talleres de refrigeración automotriz en la ciudad de Barranquilla. Luego se aplicaron las pruebas de la metodología del análisis de falla. Se comprobó que los mecanismos de falla fueron principalmente corrosión con algunas situaciones tendientes a fractura frágil; además, las condiciones ambientales de la ciudad de Barranquilla son factores influyentes en los mecanismos de corrosión.

  4. Análisis de productos de corrosión de acero ,zinc, cobre y aluminio formados en clima polar antártico

    OpenAIRE

    Chico, Belén; Fuente, Daniel de la; Morcillo, Manuel; Almeida, E.; Joseph, Günter; Rivero, S.; Rosales, B.

    2002-01-01

    Este artículo presenta los resultados de caracterización de los productos de corrosión formados sobre acero, zinc, cobre y aluminio expuestos en estaciones de corrosión antárticas cercanas a la línea de costa, analizándose la influencia de las características singulares de este clima sobre la formación de los mismos. Los resultados se comparan con los obtenidos en atmósferas marinas de climas tropicales y templados.

  5. Propiedades mecánicas de materiales compuestos de matriz de aluminio reforzados con intermetálicos

    Directory of Open Access Journals (Sweden)

    Torres, B.

    2001-04-01

    Full Text Available In this work 2124 aluminium matrix composites reinforced with Ni3Al, NiAl, MoSiO2 and Cr3Si intermetallic powder particles have been investigated. For comparision purposes, unreinforced 2124 and reinforced with SiC have also been studied. In all cases, the same powder metallurgy route was used, i.e. the 2124 alloy was obtained by rapid solidification and the intermetallic particles by self-propagating high-temperature synthesis (SHS. The matrix and the intermetallics were mechanically blended, cold compacted and finally hot extruded. Tensile tests were carried out in T1 and T4 treatments. Results indicate that mechanical properties depend strongly on the tendence to form new phases at the matrixintermetallic interface during procesing and/or futher thermal treatments. The materials which present better properties are those that present less reaction between matrix and intermetallic reinforcement, i.e. MoSiO2 and SiC reinforced composites.

    En este trabajo se estudia el comportamiento mecánico de varios materiales compuestos de matriz de aluminio 2124 reforzados con partículas de los intermetálicos, Ni3Al, NiAl, MoSiO2 y Cr3Si. Los resultados obtenidos se comparan con la aleación 2124 monolítica y con esa misma aleación reforzada con partículas del cerámico SiC. En todos los casos, se sigue la misma ruta de procesado pulvimetalúrgico a partir de polvos rápidamente solidificados, en el caso de la aleación 2124, y de la molienda mecánica de un tocho obtenido por síntesis autopropagada a temperatura elevada (SHS, para el refuerzo intermetálico. Matriz y reforzante se mezclan, mecánicamente, para, a continuación, compactar uniaxialmente en frío, procediéndose, finalmente, a la consolidación por extrusión. Las propiedades mecánicas se estudian mediante ensayos de tracción en estado T1 y T4. Los resultados obtenidos indican que las propiedades mec

  6. Aplicaciones tecnológicas de las arcillas modificadas

    OpenAIRE

    Zavala Huaytán, Candy Natalie; Zavala Huaytán, Candy Natalie; Zavala Huaytán, Candy Natalie

    2009-01-01

    Las arcillas de la familia de las esmectitas representan un grupo de minerales constituidos por filosilicatos, cuyas propiedades físico-químicas dependen de su estructura y del tamaño de grano, muy fino (menor a 2 pm). Una propiedad peculiar de estas estructuras es que presentan sustituciones isomórficas que permiten sustituir al átomo de silicio (Si), situado en el centro de los tetraedros, por otro de menor carga, como el aluminio (Al3+); igualmente, se puede reemplazar el aluminio de las c...

  7. Estudio de las fallas de soldadura en el proceso de fabricación de cilindros de aluminio para g l p

    OpenAIRE

    Torres Villamar, Artemio; Wiesner Falconi, Ignacio

    2009-01-01

    El desarrollo del presente trabajo de tesis: Estudio de las fallas de soldadura en el proceso de fabricación de cilindros de aluminio para gas licuado de petróleo, sirve para optimizar la operación de las diferentes etapas del proceso de soldadura, para el efecto se aplicaron técnicas ingenieriles, normas establecidas por el INSTITUTO ECUATORIANO DE NORMALIZACIÓN, como: INEN No. 117 e INEN No. 291 y normas internacionales como ASTM – B209 y ASTM – B211. Se realizaron análisis de fallas en...

  8. Mechanical and tribological properties enhancement of heat treated AISI 4340 steel by using a TiN/TiAlN multilayer coating system

    Directory of Open Access Journals (Sweden)

    Gilberto Bejarano

    2008-01-01

    Full Text Available Multicapas de TiN/TiAlN (nitruro de titanio/nitruro de titanio aluminio se depositaron por la técnica de la pulverización catódica d.c. reactiva utilizando blancos de titanio y de aluminio de 10 cm de diámetro, con una pureza de 99,9%, en una atmósfera de argón y nitrógeno (Ar/N, aplicando una temperatura de 300°C y una presión de 7x10-3 mbar al sustrato. Como sustratos se utilizaron silicio (100 y acero AISI 4340 tratado térmicamente con una dureza de 54 Rockwell C (HRC, aproximadamente 5,4 GPa. Recubrimientos de TiN/TiAlN con un contenido de Al de 70% y un espesor total de 4 um se investigaron en función del número de multicapas y sus propiedades mecánicas y tribológicas se compararon con las de las muestras de acero sin recubrir. La estructura cristalina de las muestras recubiertas se analizó mediante difracción de rayos X, la morfología y topografía con microscopia electrónica de barrido (SEM y microscopia de fuerza atómica (AFM. La dureza se determinó mediante nanoindentación, mientras que la resistencia al desgaste se caracterizó a través de mediciones de pin on disc. Para las 150 multicapas de TiN/TiAlN se obtuvo un incremento en la dureza y en el módulo de Young de 62% y 70% respectivamente, en relación a las 30 bicapas iniciales, y de 740% y 202% respectivamente, comparado con el acero AISI 4340 sin recubrir. Finalmente, el coeficiente de fricción se redujo de 0,55 a 0,20 y la rugosidad de 60 nm a 3,2 nm para las probetas de acero recubiertas con 150 bicapas de TiN/TiAlN, lo cual condujo a una mayor resistencia al desgaste del sistema de recubrimiento.

  9. Evaluación y planteamiento de mejoras en el proceso de maderado de aluminio utilizando técnicas de producción esbelta.

    OpenAIRE

    Larreátegui Loor, Víctor José; Barcia Villacreses, Dr. Kléber

    2011-01-01

    La tesis se desarrolló en la empresa XYZ dedicada a elaborar perfiles de aluminio con acabado de madera, situada en la ciudad de Guayaquil. La empresa cuenta con una capacidad para pintar hasta 1000 perfiles diarios en una jornada de 10 horas, dependiendo del tipo de perfil y el número de caras a pintar. La venta del producto se realiza a nivel nacional, a clientes de todo el Ecuador y se estudian posibilidades de exportación a mercados internacionales a futuro. Los principales proble...

  10. Prediction of hardness of the Zn-Al-Cu alloys of agreement by composition in weight; Prediccion de la dureza de la aleacion Zn-Al-Cu de acuerdo a su composicion en peso

    Energy Technology Data Exchange (ETDEWEB)

    Villegas-Cardenas, Jose David; Camarillo-Villegas, Alejandra; Juanico-Loran, Antonio [Universidad Politecnica del Valle de Mexico, Tultitlan, Estado de Mexico (Mexico)]. E-mails: jdvc76@yahoo.com.mx; v_c_a_77@hotmail.com; ajuanico@yahoo.com.mx; Espinosa-Rojas, Raul [Universidad Autonoma Metropolitana, Unidad Azcapotzalco (Mexico)]. E-mail: rer21@hotmail.com; Camacho-Olguin, Carlos [Universidad Politecnica del Valle de Mexico, Tultitlan, Estado de Mexico (Mexico)]. E-mail: ccamacho@upvm.edu.mx

    2013-07-15

    Ten alloys Zn-Al-Cu were developed in two parts, in agreement to two zones presented in the isopleth diagrams (Villas et al., 1995). The percentage of Cu and Al was systematically varied. Subsequently, hardness measurements were performed. These measurements allowed establishing two equations that predict the hardness with an error lower than 5%. With these equations, it is possible to obtain alloys that replace Al base alloys by a Zn base alloy, having the same hardness. This implicates also the elimination of the volumetric change in the presence of e phase. [Spanish] Se desarrollaron diez aleaciones Zn-Al-Cu divididas en dos partes, de acuerdo a dos zonas presentadas en los diagramas isopleticos de Hans (Villas et al., 1995). Se incremento el porcentaje de Cu y Al paulatinamente. Posteriormente se desarrollaron pruebas de macrodureza y de ese analisis se obtuvieron dos ecuaciones que permiten pronosticar y disenar aleaciones de una dureza determinada de acuerdo a su porcentaje en peso de cada elemento, con un error menor que 5%. Como se demuestra en este trabajo, con estas ecuaciones es posible desarrollar aleaciones sustitutas base aluminio por una aleacion base zinc o viceversa, teniendo la misma dureza para cada tipo de aleacion y eliminando el problema del cambio volumetrico debido a la presencia de la fase e.

  11. Durabilidad del aluminio desnudo y anodizado en atmósferas de muy diferentes corrosividades. II. Aluminio anodizado

    Directory of Open Access Journals (Sweden)

    López, V.

    2004-08-01

    Full Text Available The behaviour of three anodic films with thicknesses of approximately 7,17 and 28 μm is studied in atmospheric exposure at 11 natural testing stations with salinity levels ranging between 2.1 and 684 mg Cl-1m-2d-1 To evaluate the results, use was made of gravimetric techniques, electrochemical impedance spectroscopy (EIS, EDX microanalysis, standard quality control tests, optical microscopy and, occasionally, electron microscopy. It is shown that anodising with correct sealing is an appropriate solution for preventing localised corrosion of aluminium and conserving its appearance, even in atmospheres of high corrosivity, provided that an ill-defined minimum thickness threshold is passed. The 7 μm anodic films suffer corrosion after the second annual cycle in the most aggressive environments. Corrosion, when it occurs, is localised in the form of pitting or filiform corrosion.

    Se estudia el comportamiento de tres anodizados, de 7, 17 y 28 μm, aproximadamente, durante la exposición en 11 estaciones de corrosión atmosférica, con salinidades que oscilan entre 2,1 y 684 mg Cl-1m-2d-1 En la valoración de resultados se utilizaron técnicas gravimétricas, de espectroscopia de impedancia electroquímica (EIE, microanálisis por EDX, ensayos normalizados de control de calidad, microscopía óptica y, ocasionalmente, microscopía electrónica. Se demuestra que la anodización, con un sellado correcto y siempre que supere un umbral mínimo de espesor, no bien definido, es una solución adecuada para prevenir la corrosión localizada del aluminio y conservar el aspecto, incluso, en atmósferas de elevada corrosividad. Los anodizados de 7 μm sufren corrosión, en los ambientes más agresivos, a partir del segundo ciclo anual. La corrosión, cuando se presenta, es localizada, en forma de picaduras o de corrosión filiforme. Palabras clave

  12. Análisis de criticidad de equipos para el mejoramiento del sistema de gestión del mantenimiento en la empresa de aluminios CEDAL.

    OpenAIRE

    Tandalla Guanoquiza, Diego Fabián

    2017-01-01

    La investigación tuvo como objetivo, realizar el análisis de criticidad de equipos para mejorar el sistema de gestión del mantenimiento en la empresa de aluminios CEDAL. La metodología está fundamentada en: la teoría del riesgo de tipo cuantitativo, Norsok.Z008, ISO-14224, EN-16646 y ISO-31000; conformada por seis fases: iniciando con la selección del activo físico, diagnóstico del contexto operacional, posteriormente se realizó la selección d...

  13. Simulación y experimentación de laminación plana de placas de aluminio 6063

    Directory of Open Access Journals (Sweden)

    Teresa Robert

    2011-06-01

    Full Text Available An experimental methodology was generated for understanding the theoretical and practical concepts inherent to cold flat rolling. Aluminium slabs about 100 mm length, 9 mm thickness with different widths: 10 and 30 mm were rolled. A constant 0.3 mm thickness reduction step was performed in order to achieve a thickness reduction greater than 80 %. In the Abaqus® commercial software, a mathematical model was implemented in order to obtain a greater understanding concerning how the process variables affect the fields of stresses and strains that are not observed experimentally. It was found, by mathematical simulation, that a superficial hardening in the plates was produced and the deformation obtained is heterogeneous, which is corroborated physically. Keywords: Flat rolling; 6063 Aluminium; Data acquisition system; Simulation Se generó una metodología experimental para el entendimiento teórico-práctico de los conceptos del proceso de laminación plana en frío. Se laminaron placas de aluminio de aproximadamente 100 mm de longitud y 9 mm de espesor, a diferentes anchos: 10 y 30 mm. Se seleccionó una razón de reducción constante de 0.3 mm para cada paso de laminación, hasta lograr una reducción superior al 80 % en espesor. Se implementó un modelo matemático en el paquete comercial Abaqus® con el fin de obtener un mayor entendimiento sobre la influencia de las variables del proceso (fuerza aplicada y dimensiones de las probetas en los campos de esfuerzos y deformaciones que, experimentalmente, no se pueden observar. Se encontró, mediante la simulación matemática, que se produce un endurecimiento superficial en las placas y que la deformación obtenida es heterogénea, lo cual se corrobora físicamente.

  14. MICROSTRUCTURAL ANALYSIS OF Al-Mg-Si-Zn ALLOY

    Directory of Open Access Journals (Sweden)

    SERGIO VALADEZ

    2010-01-01

    Full Text Available En un esfuerzo por desarrollar una nueva aleación con aplicación estructural, se ha desarrollado una aleación base Aluminio aleada con magnesio, silicio y zinc. La investigación pretende correlacionar la microestructura y con el tratamiento térmico. La aleación AlMgSiZn, fue elegida para ese propósito debido a la presencia de precipitados tanto en la matriz del aAl, como en los límites de grano, los cuales permiten una excelente relación entre la dureza y la resistencia mecánica. En lo que respecta a la microestructura, esta fue caracterizada bajo condición de colada y después de ser tratada térmicamente por envejecimiento. Este tratamiento fue realizado en dos etapas, la primera a 450ºC durante 3 horas que corresponde al tratamiento de homogeneización: y la segunda al proceso de envejecimiento artificial llevado a cabo a 160ºC durante 1hr. Los resultados indican la presencia de dendritas de aAl, además un eutéctico binario y partículas de Mg7Zn3 adentro de las regiones interdendríticas. El eutéctico y las partículas fueron modificados por el tratamiento de envejecido. Las observaciones realizadas con el microscopio electrónico de transmisión en especímenes con y sin tratamientos térmicos, demostraron una distribución uniforme de precipitados con diversas morfologías, tales como cúbico, esférico y plaqueta: para la matriz de aAl, los cuales no fueron detectados durante las observaciones en el microscopio electrónico de barrido.

  15. Influences of argon gas shielding on diffusion bonding of Ti-6Al-4V alloy to aluminum; Influencia del argón como gas protector en la difusión durante el proceso de unión de la aleación Ti6Al4V con el aluminio

    Energy Technology Data Exchange (ETDEWEB)

    Akcaa, A.; Gursela, A.

    2017-09-01

    This study presents a diffusion bonding process of commercially pure aluminum to Ti-6Al-4V alloy. Prepared samples were exposed to temperature of 560, 600 and 640 °C for the bonding time of 30, 45 and 60 min at the atmosphere of argon gas and non-argon. Diffusion bonding is a dissimilar metal welding process which can be applied to the materials without causing any physical deformations. The processed samples were also metallographically prepared, optically examined followed by Vickers microhardness test in order to determine joint strength. Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) were used in this work to investigate the compositional changes in order to observe the influence of atmosphere shielding in the transition zone. The result of tests and analyses were tried to be compared with the effect of argon shielding. The significant influences have been observed in the argon shielding during diffusion bonding process. [Spanish] Este estudio presenta los procesos de difusión durante la unión de aluminio puro con la aleación Ti6Al4V. Se expusieron probetas a las temperaturas de 560, 600 y 640 ºC durante un tiempo de unión de 30, 45 y 60 min en una atmósfera en presencia y ausencia de gas argón. La unión por difusión es un proceso de soldadura entre metales distintos que puede ser aplicado a los materiales sin causar deformaciones físicas. Las probetas procesadas fueron preparadas también metalográficamente, examinadas por miscroscopía óptica, seguido de ensayos de microdureza Vickers para determinar el límite elástico. Se utilizó microscopía electrónica de barrido (SEM) y espectroscopía de energias dispersivas (EDS) para determinar los cambios en la composición y estudiar la influencia del argón como gas protector en la zona de transición. La influencia más importante se ha observado durante el proceso de difusión en estado sólido.

  16. Formación de porosidad durante la soldadura láser de Nd: YAG de onda continua en aleaciones de aluminio para aplicaciones automotrices

    Directory of Open Access Journals (Sweden)

    Pastor, Mario

    2000-04-01

    Full Text Available Pore formation is an important concern in laser welding of automotive aluminum alloys. This paper investigates the influence of the laser beam defocusing on pore formation during continuous wave Nd: YAG laser welding of aluminum automotive alloys 5182 and 5754. It was found that the instability of the keyhole during welding was a dominant cause of pore formation while hydrogen rejection played an insignificant role. The defocusing of the laser beam greatly affected the stability of the keyhole. Finally, the mechanism of the collapse of the keyhole and pore formation is proposed.

    La formación de poros es un aspecto de gran preocupación durante la soldadura láser de aleaciones de aluminio. En este trabajo se ha investigado la influencia del desenfoque del haz del láser sobre la formación de poros durante la soldadura láser (Nd: YAG de onda continua de las aleaciones de aluminio 5182 y 5754, las mismas que se usan en aplicaciones automotrices. Los resultados obtenidos indicaron que la causa dominante de formación de poros fue la inestabilidad de la cavidad de vapor o keyhole mientras que la influencia del hidrógeno fue prácticamente insignificante. El grado de desenfoque del láser tuvo gran influencia sobre la inestabilidad de la cavidad de vapor. Finalmente, en este artículo se propone el mecanismo de formación de poros a causa del colapso de la cavidad de vapor (keyhole.

  17. Description of hypoeutectic Al-Si-Cu alloys based on their known chemical compositions

    Directory of Open Access Journals (Sweden)

    Djurdjevic, M. B.

    2013-10-01

    interés durante las últimas décadas, y la cantidad de programas de simulación existentes en el mercado es un buen indicador del interés de la industria en este campo. La mayoría de los datos empleados en estos programas se basan en los diagramas de fase binarios, ternarios o incluso superiores. Desafortunadamente, excepto para los diagramas binarios, el ajuste de los datos no es lo suficiente bueno. Teniendo en cuenta que la mayoría de los sistemas binarios del aluminio están bien definidos se ha intentado convertir los sistemas multi-componentes en un pseudo binario sistema Al-Xi (en este caso el diagrama de fase Al-Si es el elegido como sistema de referencia. El nuevo algoritmo del Silicio Equivalente (SiEQ expresa la cantidad de los elementos de la aleación que son mayoritarios y minoritarios, a través de una cantidad “equivalente” de silicio. Este sistema puede emplearse para calcular varias características termo-físicas y de solidificación de sistemas multicomponentes, como las aleaciones de aluminio. Esto permite al modelo tener la capacidad de realizar predicciones de las características de la solidificación de las piezas fundidas, donde las velocidades de enfriamiento son bajas y las características del proceso de solidificación son bien conocidas, para evitar posibles problemas en la fundición. Este trabajo demuestra cómo el algoritmo del SiEQ puede ser empleado para el cálculo de las características de las temperaturas de solidificación de las aleaciones multi-componentes Al-Si, así como sus calores latentes y el factor de restricción del crecimiento del grano. El análisis estadístico de los resultados obtenidos en un amplio rango de composiciones químicas de la aleación, muestra una muy buena correlación entre los datos experimentales y los cálculos realizados con el SiEQ. La misma aproximación matemática podría ser aplicada para otros sistemas metálicos como el hierro y el magnesio, empleando el carbono equivalente en el

  18. Laser surface alloying of aluminium-transition metal alloys

    Directory of Open Access Journals (Sweden)

    Almeida, A.

    1998-04-01

    Full Text Available Laser surface alloying has been used as a tool to produce hard and corrosion resistant Al-transition metal (TM alloys. Cr and Mo are particularly interesting alloying elements to produce stable highstrength alloys because they present low diffusion coefficients and solid solubility in Al. To produce Al-TM surface alloys a two-step laser process was developed: firstly, the material is alloyed using low scanning speed and secondly, the microstructure is modified by a refinement step. This process was used in the production of Al-Cr, Al-Mo and Al-Nb surface alloys by alloying Cr, Mo or Nb powder into an Al and 7175 Al alloy substrate using a CO2 laser. This paper presents a review of the work that has been developed at Instituto Superior Tecnico on laser alloying of Al-TM alloys, over the last years.

    En el presente trabajo se estudia la aleación superficial mediante láser de aluminio con metales de transición. El cromo y el molibdeno son particularmente interesantes porque producen aleaciones de alta resistencia y por el bajo coeficiente de difusión y solución sólida en aluminio. Para producir estas aleaciones se ha seguido un procedimiento desarrollado en dos partes. En primer lugar, el material se alea usando una baja velocidad de procesado y en segundo lugar la estructura se modifica mediante un refinamiento posterior. Este procedimiento se ha empleado en la producción de aleaciones Al-Cr, Al-Mo y Al-Nb mediante aleación con láser de CO2 de polvos de Cr, Mo o Nb en aluminio y la aleación 7175. Este trabajo es una revisión del desarrollado en el Instituto Superior Técnico de Lisboa en los últimos años.

  19. Utilización del mucílago de tuna (opuntia ficus-indica) en el mejoramiento de la calidad del agua de consumo humano, en la comunidad de Pusir Grande, provincia del Carchi

    OpenAIRE

    Morejón Díaz, Bayro Javier

    2017-01-01

    Mejorar la calidad del agua de consumo humano utilizando mucílago de tuna (Opuntia ficus-indica) en la comunidad de Pusir Grande, Provincia del Carchi. Dentro del proceso para tratamiento de agua para consumo humano, se utilizan coagulantes químicos como el Sulfato de Aluminio Al2 (SO4)3, sin embargo, según estudios realizados, se ha comprobado que este insumo deja aluminio residual, el mismo que podría causar enfermedades como el Alzheimer. En la naturaleza, existen especies vegetativa...

  20. Propiedades mecánicas y tribológicas del material antifricción Al-Ni-grafito obtenido mediante extrusión en caliente

    Directory of Open Access Journals (Sweden)

    Cambronero, L. E. G.

    2004-04-01

    Full Text Available Manufacturing and characterization of bearing materials is the object of the present work. Thus, graphite particles are added to an aluminium matrix as lubricant. It was added as nickel coated graphite in order to avoid a strength decreasing. Mixing of powders following by cold compaction and hot extrusion was the manufacturing way. Extruded materials showed good graphite distribution into the aluminium matrix, with densities between 3.11 to 3.75 g/cm3 as a function of the nickel/graphite content. Hardness and radial crushing strength decrease when graphite content is increased. On the contrary, friction properties are improved with the graphite content because it decreases friction coefficient and wear. Diffusion heat treatment on extruded materials improves furthermore these friction properties but it decreases the radial crushing strength.

    El objeto de este trabajo es la obtención y caracterización de materiales compuestos (MMC´s para la fabricación de cojinetes para fricción en seco. Así se incorpora a una matriz de aluminio, partículas de grafito para actuar como lubricante si bien en forma de grafito recubierto de níquel para disminuir la perdida de resistencia que presentan estos materiales. La fabricación de estos materiales se realizó mediante compactación de las mezclas de polvos en matriz y su extrusión en caliente. Los materiales obtenidos presentaron una buena distribución del grafito en la matriz de aluminio, con densidades entre 3.11 g/cm3 y 3.75 g/cm3 según el contenido de níquel/grafito. La dureza y la resistencia al aplastamiento radial disminuyen al aumentar el contenido en grafito. No obstante, un mayor contenido en grafito si mejora las propiedades a fricción del material, disminuyendo el desgaste ocasionado y reduciendo el coeficiente de fricción. El tratamiento térmico de difusión de los materiales extruidos mejora sus propiedades de fricción si bien disminuye su resistencia al aplastamiento

  1. Efectos del polihidroxicloruro de aluminio, velocidad de agitación y pH en la turbidez del agua del Río Shullcas -Huancayo, 2013

    OpenAIRE

    Claros Castellares, Jaime Herminio

    2015-01-01

    El propósito de la tesis fue evaluar los efectos del polihidroxicloruro de aluminio, velocidad de agitación y pH en la turbidez del agua del río Shullcas en la localidad de Huancayo, en el año 2013 y aplicar en el tratamiento de agua potable a fin de lograr un producto de turbidez óptima. Basado en modelos físicos y químicos se desarrolló una investigación aplicada del proceso de clarificación (coagulación, floculación y sedimentación), de nivel explicativo, utilizando el método de investigac...

  2. Aplicaciones tecnológicas de las arcillas modificadas

    OpenAIRE

    Picasso, Gino; Sun Kou, María del Rosario

    2008-01-01

    Las arcillas de la familia de las esmectitas representan un grupo de minerales constituidos por filosilicatos, cuyas propiedades físico-químicas dependen de su estructura y del tamaño de grano, muy fino (menor a 2 µm). Una propiedad peculiar de estas estructuras es que presentan sustituciones isomórficas que permiten sustituir al átomo de silicio (Si), situado en el centro de los tetraedros, por otro de menor carga, como el aluminio (A1(3+)); igualmente, se puede reemplazar el aluminio de las...

  3. Long-term performance of different aluminum alloy designs as sacrificial anodes for rebars

    Directory of Open Access Journals (Sweden)

    de Rincón, O.

    2003-12-01

    Full Text Available This paper presents the performance of various cathodic-protection designs using Aluminum alloys to protect prestressed piles. The results obtained with different system designs (bracelete type-Al/Zn/In alloy, thermosprayed aluminum (3-year evaluation and conventional Al/Zn/In anocies in an epoxy-painted steel bracelet (12-year evaluation, indicated that all of these systems may be used as sacrificial anodes for pile protection. However, the thermosprayed aluminum type can not be used in prestressed concrete piles because the very negative potentials ( < -1100 mV vs. Cu/CuSO4 they supply to the reinforcement could lead to hydrogen embrittlement.

    Este trabajo presenta la realización de varios diseños de protección catódica utilizando aleaciones de aluminio para la protección de pilotes pretensados. Los resultados obtenidos con diferentes diseños (aleación de Al/Zn/In, tipo brazalete y aluminio termorociado (3 años de evaluación y ánodos convencionales de Al/Zn/In colocados en un brazalete de acero pintado con epoxy (12 años de evaluación, indicaron que todos estos sistemas pueden ser utilizados como ánodos de sacrificio para la protección de los pilotes. Sin embargo, el sistema con aluminio termorociado no puede ser utilizado en pilotes de acero pretensado debido al potencial muy negativo alcanzado por la armadura (<-1100 mV vs Cu/CuSO4, lo cual podría inducir a daños por hidrógeno.

  4. Tensión superficial, viscosidad y densidad de algunas escorias CaO-Al2O3

    Directory of Open Access Journals (Sweden)

    Oliveira, F. A.

    1999-04-01

    tensión superficial disminuye con el aumento de la relación molar CaO: Al2O3 o con el aumento de la temperatura, en tanto que la viscosidad aumenta con la elevación del contenido de alúmina y disminuye con el aumento de la temperatura. El comportamiento observado en los valores de tensión superficial y viscosidad con la variación de la composición, puede estar asociado a la presencia de algunos iones de aluminio en coordinación octaédrica que, a su vez, pueden presentar una proporción de aluminatos conteniendo iones de aluminio en reducido estado de valencia, tal como Al2+.

  5. Oxidación en vapor de agua a 700 ºC y 750 ºC del acero inoxidable AISI 317 recubierto con aluminio por CVD-FBR.

    OpenAIRE

    Jose L. Marulanda; Saul I. Castañeda; Aduljay Remolina

    2014-01-01

    Se realizó la oxidación del acero inoxidable austenítico AISI 317 recubierto con aluminio por deposición química de vapor en lecho fluidizado, a temperaturas de 700 °C y 750ºC, en un ambiente con 100% vapor de agua, para evaluar su comportamiento. Se realizaron curvas de ganancia de masa y las películas de óxidos se analizaron por medio de SEM y difracción de rayos X, para observar la morfología de los óxidos. Se realizó la simulación termodinámica del proceso de oxidación en vapor de agua de...

  6. Influencia de la composición y las condiciones de procesado en la resistencia a la corrosión de materiales compuestos base aluminio

    Directory of Open Access Journals (Sweden)

    Jiménez-Morales, A.

    2004-04-01

    Full Text Available This work tries to analyze the corrosion behavior of a serie of composite materials, as well as to study the influence of the reinforcement and milling technique on the unreinforced base alloy corrosion resistance. For this purpose composite materials, base 6061 aluminum alloy and reinforced with Si3N4, ZrB2 and AlN (5% wt. have been manufactured, by means of both low and high energy milling techniques for the blending step. The study is mainly focused on the evolution of the corrosion potential versus time, pitting potential as well as the pasive zone of each material by means of continuous current electrochemical techniques. The most significant results reveal the influence of the reinforcement as well as the employment of different blending techniques, both on the corrosion and pitting potential.

    Este trabajo trata de analizar el comportamiento frente a la corrosión de una serie de materiales compuestos, así como de estudiar la influencia del refuerzo y el tipo de molienda con respecto a la aleación base sin reforzar. Para ello, se ha fabricado una serie de materiales compuestos con matriz de aluminio, aleación 6061, reforzados con un 5% en peso de Si3N4, ZrB2 y AlN, empleando como técnicas de mezcla y homogeneización dos tipos de molienda, de baja y alta energía, respectivamente. El trabajo se ha basado principalmente en el estudio de la evolución con el tiempo del potencial de corrosión, del potencial de picadura y de la zona pasiva de cada material por técnicas electroquímicas de corriente continua. Los resultados más significativos revelan la influencia tanto del refuerzo como del empleo de las distintas técnicas de mezcla, tanto en el potencial de corrosión como en el de picadura.

  7. Diseño y construcción de un equipo para ensayo de deflexión en vigas de aluminio, en voladizo. Capacidad de carga de 10 kg.

    OpenAIRE

    Oña Caiza, Luis Alberto; Reinoso Sacancela, Armando Rodrigo

    2010-01-01

    En la actualidad con el avance de la tecnología y con la implementación de nuevos equipos para ensayos de deflexión en los materiales conlleva a la necesidad de elaborar un equipo de ensayo de deflexión para vigas en voladizo (viga rectangular y perfil U), en material de aluminio para la utilización en el laboratorio de resistencia de materiales de la Universidad Politécnica Salesiana. Para la selección de la alternativa más adecuada se realizó un estudio del costo real de la máquina en e...

  8. Comportamiento de las herramientas de conformado con recubrimientos TiAlN crecido por Magnetrón Sputtering Tríodo

    Directory of Open Access Journals (Sweden)

    Diana Marcela Devia-Narváez

    2015-01-01

    Full Text Available Esta investigación se enfoca en el análisis tribológico de los recubrimientos de nitruro de titanio aluminio (TiAlN depositad os por la técnica Magnetrón Sputtering Tríodo, cuando se utilizan como ca pa protectora en herr amientas de conformado. El análisis se rea liza a partir de las propiedades microestructurales que influyen direc tamente en el comportamiento tribológico. Se observó que los me canismos de desgaste predominantes en la superficie son la delaminación y la tribo-oxidación; se determinó un incremento en la vida úti l de la herramienta siendo lo s recubrimientos duros u na excelente alter nativa en la industria metalmecánica.

  9. Caracterización mecánica de recubrimientos de aluminio por CVD-FBR sobre aceros inoxidables y resistencia a la oxidación en vapor de agua

    OpenAIRE

    Diego Pérez-Muñoz; José Luddey Marulanda-Arévalo; Juan Manuel Meza-Meza

    2015-01-01

    Los recubrimientos de aluminio depositados sobre el acero inoxidable austenítico AISI 317 por Deposición Química de Vapor en Lecho Fluidizado (CVD-FBR) presentan a altas temperaturas una reducción de la velocidad de corrosión de más de 80 veces. Se realizó la caracterización mecánica de los recubrimientos por medio de microdureza, nanoindentación, para conocer cómo se vieron afectas las propiedades mecánicas (en especial la dureza y el módulo de Young) del recubrimiento y del sustrato luego d...

  10. Formación de titanato de aluminio por reacción en estado sólido de alúmina y titania

    Directory of Open Access Journals (Sweden)

    Uribe, R.

    2000-04-01

    Full Text Available In this work, the formation of Al2TiO5 from equimolar mixtures of high purity and fine grained (d50< 50μm Al2O3 and TiO2 powders and the influence of the microstructure of the obtained compacts on the milling efficiency have been studied. Different thermal treatments with maximum temperatures between 1350 and 1650ºC have been considered and their influence in the degree of reaction and the cell size of Al2TiO5 have been established. Green compacts have been obtained by isostatic pressing. Some compacts have been thermally treated between 1350 and 1650ºC using a single thermal cycle. The other compacts have been thermally treated in two stages using 1600ºC as maximum temperature, with an intermediate process of grinding, milling and pressing after the initial low temperature (1350-1500ºC treatment. The evolution of the reaction has been studied by X-ray diffraction, optical microscopy and scanning electron microscopy. The efficiency of the milling processes has been followed using the evolution of the particle size distribution. The results showed that the degree of reaction changes from practically no reaction at 1350ºC to the complete reaction at 1650ºC, except for the presence of some isolated alumina particles. The thermal treatment conditions used to obtain the materials determine the obtained microstructures of Al2TiO5 and hence affect the grinding conditions.

    En el presente trabajo se ha estudiado el efecto que tienen las condiciones de tratamiento térmico (entre 1350 y 1650ºC en la reacción de formación Al2TiO5, a partir de la mezcla equimolar de polvos finos (diámetro promedio < 0.5μm de alúmina y titania de elevada pureza. Se ha determinado la influencia de las condiciones de tratamiento térmico en el grado de reacción de formación del Al2TiO5, el tamaño de las celdas de Al2TiO5 formadas y en la eficiencia de la posterior molienda de los materiales. Los compactos preparados a partir de la mezcla de los polvos

  11. Efecto de tres preservadores de la longevidad sobre la vida postcosecha de Rosa cv. Royalty

    Directory of Open Access Journals (Sweden)

    G. H. De la Cruz-Guzmán

    2007-01-01

    Full Text Available Se evaluó el efecto de tres tratamientos: a sulfato de aluminio 0.6 g·l-1; b 400 ppm de sulfato de 8-hidroxiquinoleina (8-HQS; c pulso con tiosulfato de plata (STS, 0.025 mM durante 20 minutos y agua destilada como testigo sobre consumo hídrico, peso fresco, diámetro floral, concentración de azúcares solubles totales en pétalos y longevidad en Rosa cv. Royalty. En el testigo el consumo de agua descendió significativamente al noveno día, no así en los otros tratamientos que se mantuvieron por arriba del testigo hasta el final del experimento. La menor tasa de pérdida de peso fresco se observó en el tratamiento con sulfato de aluminio (Al, seguido por STS, HQS y testigo respectivamente, sugiriendo una probable asociación inversa con la vida postcosecha. Las flores tratadas con sulfato de aluminio, resultaron estadísticamente diferentes en cuanto a su estado ornamental óptimo en los días 9, 10, 11, 12 y 14 de vida postcosecha, evaluados mediante la prueba de Kruskall-Wallis El diámetro floral fue mayor en las flores tratadas con STS (9 cm, seguido por sulfato de aluminio (7.6 cm; éste último mantuvo la apertura dos días más que STS. En cuanto a la concentración de azúcares solubles totales en estado de botón y flor abierta, no se registraron diferencias significativas (P>0.05 ni entre tratamientos ni estados florales.

  12. Innovative processing for improved electrical steel properties

    Directory of Open Access Journals (Sweden)

    Schneider, J.

    2010-10-01

    Full Text Available Electrical steel grades are the normal construction material for electrical motors and transformers because of their enhanced soft magnetic properties. One of the current trends in their production aims for increasing the silicon and/or aluminum concentration (above 3 wt % to reduce magnetic losses through increased electrical resistivity. This is very difficult to realize by conventional processing, mainly because of cracking during cold rolling. An alternative production route is proposed that raises the silicon and/or aluminum concentration by surface deposition of silicon and/or aluminum on a low-Si/low-Al steel substrate, e.g. by a short immersion in a molten Al-Si bath, followed by its diffusion into the bulk during subsequent annealing. This diffusion substantially modifies the microstructural features and therefore affects the mechanical and magnetic properties. Results of research efforts to optimize this production route and to understand the mechanisms and effects of the structural changes are presented and discussed.Los aceros eléctricos se usan, normalmente, en la construcción de motores eléctricos y transformadores debido a sus suaves propiedades magnéticas. Una de las tendencias actuales es producir aceros con contenidos mayores de silicio y/o aluminio (por encima de un 3 %, en peso para reducir las pérdidas magnéticas a través del incremento de la resistividad eléctrica. Una de las desventajas de producir este tipo de aceros con altos contenidos de silicio y/o aluminio es el agrietamiento producido en el material durante el proceso de laminado en frío. Para incrementar el contenido de silicio y/o aluminio en aceros con bajos contenidos de estos elementos de aleación, se sugiere un procedimiento alternativo de producción que se basa, fundamentalmente, en depositar un recubrimiento rico en silicio y/o aluminio, en la superficie del acero. Por ejemplo, uno de los métodos utilizados es sumergir el material en una aleaci

  13. Desarrollo y caracterización de un material compuesto de matriz de aluminio 6061 y partículas de TiB2

    Directory of Open Access Journals (Sweden)

    Plaza, L. M.

    2010-12-01

    Full Text Available The incorporation of ceramic particles has been one of the ways developed to improve the mechanical properties of aluminium alloys during the last years. The main objective of this work has been to develop the manufacturing process of the reinforced aluminium alloy and analyse its mechanical properties and microstructure. Details about an innovative MMC manufacturing process and the results obtained in the development of a new family of TiB2- reinforced aluminium alloys for forging and extrusion applications are presented. It has been observed that the considered manufacturing process, consisting in the fabrication of particles by SHS and their incorporation into the selected alloy, is a feasible process to manufacture reinforced alloys that can be subsequently extruded or forged. The final result is the development of a material suitable for extrusion and forging applications and that presents an improvement of fatigue and tensile properties of the matrix alloy.Una de las vías desarrolladas, en los últimos años, para la mejora de las propiedades mecánicas de las aleaciones de aluminio es la de la incorporación de refuerzos cerámicos en forma de partículas cerámicas. El objetivo principal del trabajo ha sido desarrollar el proceso de fabricación de una aleación de aluminio 6061 reforzada con partículas de diboruro de titanio, TiB2, y analizar las propiedades del material obtenido. Se ha observado que el proceso de fabricación planteado, consistente en la fabricación de las partículas por medio del proceso de síntesis autopropagada a alta temperatura SHS (Self propagating high temperature synthesis y su posterior incorporación a la aleación 6061, es un proceso viable para la fabricación de aleaciones reforzadas adecuadas para la realización de procesos subsiguientes de extrusión o forja. El resultado final es la obtención de un material adecuado para la fabricación de componentes extruidos y que presenta una mejora de sus

  14. Influencia de las mezclas de gases Ar-He y Ar-He-O2 en la soldabilidad de la aleación de aluminio AA5083-O usando Proceso GMAW-P automatizado

    Directory of Open Access Journals (Sweden)

    Enrique Esteban Niebles Nuñez

    2014-09-01

    Full Text Available La problemática en las empresas fabricantes de estructuras y construcciones soldadas en aluminio se centra en la disminución de las propiedades mecánicas de las uniones soldadas influenciada por el aporte térmico en las regiones de soldadura; así como, en los efectos de las discontinuidades y defectos, los altos costos de reparación de soldaduras y la baja productividad. El objetivo de este trabajo es evaluar la influencia de las mezclas de gases 80Ar20He (MG1, 60Ar40He (MG2, 80Ar19He1O2 (MG3, 60Ar39He1O2 (MG4, sobre la soldabilidad de la aleación de aluminio AA5083-O utilizando un material de aporte ER5183 y el proceso GMAW-P automatizado. La metodología incluyó una fase de parametrización de soldaduras, la caracterización del metal base y las regiones de soldadura. El análisis de resultados se llevó a cabo en términos de la evolución microestructural en las regiones de soldadura y evaluación de las propiedades como dureza, resistencia y elongación, así como la evaluación de discontinuidades y defectos de la unión, costos y velocidad de soldadura. Los resultados muestran que las mezclas de gas que contienen O2 favorecen significativamente la soldabilidad de la aleación en estudio.

  15. A modification of the method for determining current efficiency of aluminium electrolytic cells; Modification de la methode permettant de determiner le rendement des cuves dans la production d'aluminium par electrolyse; Izmenenie metoda opredeleniya ehffektivnosti toka v alyuminievykh ehlektroliticheskikh bakakh; Modificacion del metodo para determinar el rendimiento de las celdas utilizadas en la produccion de aluminio por electrolisis

    Energy Technology Data Exchange (ETDEWEB)

    Pradzynski, A [Institute of Basic Technical Problems, Polish Academy of Sciences. Warsaw (Poland); Orman, Z [Institute of Nonferrous Metals, Gliwice (Poland)

    1962-01-15

    de faciliter l'application de cette methode dans les usines d'aluminium et d'eviter toutes les restrictions et tous les dangers qu'entraine la manipulation, en dehors des laboratoires speciaux pour l'etude des radioisotopes, de sources radioactives non scellees. De l'or inactif a ete introduit dans' l'alliage type et dans le bain de la cuve electrolytique. La concentration d'or dans les echantillons d'alliage type et dans les echantillons preleves dans la cuve a ete mesuree apres irradiation de ces echantillons dans un reacteur nucleaire. (author) [Spanish] El procedimiento para determinar el rendimiento de las celdas para la produccion de aluminio por electrolisis fue descrito inicialmente por Rempel y col. y fue perfeccionado por Bozoky y col. que emplearon el radioisotopo {sup 198}Au. Este procedimiento consiste en preparar aleaciones tipo de aluminio con {sup 198}Au y medir la elevada actividad especifica de muestras de la aleacion con un tubo Geiger-Mueller, introduciendo plomo como absorbente entre el tubo y la muestra. Los autores midieron la actividad especifica de la aleacion tipo despues de diluirla con una cantidad conocida de aluminio puro. De esta manera, las muestras de aleacion tipo diluida y las muestras tomadas en la celda electrolitica tienen una actividad especifica del mismo orden de magnitud, que puede ser medida sin necesidad de absorbente. Los autores han recurrido al analisis por radiactivacion con objeto de facilitar la aplicacion de este procedimiento en las fabricas de aluminio y evitar las restricciones y los peligros que supone la utilizacion de fuentes de radiacion no encerradas fuera .de los laboratorios de radioisotopos. El procedimiento consiste en introducir oro inactivo en la aleacion tipo y en la masa fundida de la celda electrolitica. Se extraen muestras de la aleacion y del electrolito y, despues de irradiarlas en un reactor nuclear, se determina la concentracion de oro. (author) [Russian] Metod opredeleniya ehffektivnosti toka v

  16. Metalografía a color en aleaciones Al-Si comerciales. Optimización de las técnicas de caracterización microestructural mediante microscopía óptica de reflexión

    Directory of Open Access Journals (Sweden)

    Vander-Voort, G. F.

    2010-10-01

    Full Text Available The present demand on alloy production with improved quality requires the optimization of the metallographic procedures used on its characterization. Traditional etching techniques commonly employed for phase identification by optical metallography in aluminium alloys are not always suitable for a detailed analysis of existing phases, nor to accurately predict the mechanisms that govern the solidification process in certain detail. This work explores the potential of colour metallography to reveal at its best as-cast microstructures in Al-Si 12 alloys. For this purpose a colour etching technique, specifically developed for aluminium alloys and based on the Weck reagent. The application of such etchant has allowed the qualitative characterization of the microstructure. And it has also shown the advantages of colour metallography over black and white (B&W etching techniques.La demanda de aleaciones con calidades optimizadas conlleva la mejora continua de estas calidades, lo que viene suscitando la necesidad de mejora y optimización permanentes de las técnicas de caracterización metalográfica. Las técnicas de ataque tradicionales, utilizadas en la observación microscópica de las aleaciones de aluminio, no permiten un análisis detallado de la evolución microestructural de las fases presentes ni de parte de los mecanismos que rigen la solidificación. En el presente trabajo, se explora el potencial de la metalografía en color aplicada a las estructuras de solidificación de aleaciones Al-Si 12. Se ha utilizado un procedimiento de ataque en color, basado en un reactivo desarrollado porWeck para aleaciones de aluminio. El empleo de esta técnica ha permitido la evaluación cualitativa de la microestructura. La técnica ha permitido revelar características microestructurales que los métodos de ataque en blanco-negro no revelan.

  17. Estudio cinético de la eliminación de magnesio en las aleaciones de aluminio mediante la inyección de polvos de sílice

    Directory of Open Access Journals (Sweden)

    Escobedo, J. C.

    2003-06-01

    Full Text Available A kinetic study on the magnesium removal from molten aluminium alloys using submerged SiO2 powders injection is presented. The variables analysed were the chemical content and the particle size of the solid agents, the melt temperature and the injection rate. It was possible to decrease the magnesium content from 1.2 to 0.02wt %, with a low inclusions content. As the main mechanism of the magnesium removal process is of diffusive type, the global process rate increases as the temperature and the injection rate are increased, while decreasing particle size. In all the cases studied, a first order global process was determined and the global rate constants were also evaluated.

    Se presenta un estudio cinético de la eliminación de magnesio de una aleación base aluminio líquida, utilizando la técnica de inyección de agentes sólidos base SiO2 transportados por un gas inerte. Las variables estudiadas son: la composición de los agentes sólidos, la temperatura del baño metálico, la velocidad de inyección y el tamaño de partícula de los agentes sólidos. Se logró disminuir el contenido de magnesio en la aleación, desde 1,2 hasta 0,02 % en peso, encontrándose que, debido a que el mecanismo que gobierna la cinética de eliminación de magnesio es de carácter difusivo, la velocidad de reacción aumenta al incrementarse la temperatura y la velocidad de inyección y al disminuirse el tamaño de partícula. También, se determinó que el proceso de eliminación de magnesio es de primer orden, evaluándose, además, las constantes de velocidad del proceso global a las diferentes condiciones experimentales empleadas.

  18. DESIGN AND CHARACTERIZATION OF THERMALLY ACTUATED BIMETALLIC MEMBRANES BY MICHELSON INTERFEROMETRY

    Directory of Open Access Journals (Sweden)

    JULIO ENRIQUE DUARTE

    2011-01-01

    Full Text Available En el presente trabajo se describen el diseño y la caracterización de membranas bimetálicas de Al-Si, con actuación térmica. El diseño se realizó empleando el método de los Elementos Finitos y se concentró en optimizar la relación de los espesores de las capas de aluminio y silicio. La defl exión de las membranas se determinó aplicando la técnica del Interferómetro de Michelson. En la etapa experimental se utilizaron membranas cuadradas de 5 mm de lado, con un espesor de 10 mm para el silicio y espesores de 4 y 1 mm para el aluminio. La caracterización entregó un desplazamiento máximo de 14 mm para la membrana con 4 mm de Al, lo cual es consistente con los resultados obtenidos numéricamente.

  19. Determinación de la variación de entalpía de la interacción entre el herbicida glifosato, y los iones de calcio, zinc y aluminio en solución acuosa por calorimetría isotérmica de titulación.

    Directory of Open Access Journals (Sweden)

    Flavio Adriano Bastos

    2010-12-01

    Full Text Available El glifosato [N-(fosfonometil glicina] es una molécula no selectivo ampliamente utilizado en Brasil como un desecante en los cultivos sin labranza, entre las hileras de los cultivos perennes y para la eliminación de las malezas en ambientes acuáticos. Es el herbicida más usado en el mundo. Debido a la presencia de grupos amino, carboxílico y fosfónico en su molécula, este herbicida es capaz de formar complejos con metales fuertes. El objetivo de este trabajo fue la determinación de los parámetros de la termodinámica de las interacciones entre el glifosato y el calcio, cobre, zinc y aluminio por calorimetría isotérmica de titulación (ITC. Los experimentos se llevaron a cabo a 298,15 K en una solución acuosa de pH controlado y es igual a 2,00. El tratamiento de los datos se realizó por el Método de la Tangente. Los resultados para el cambio de entalpía (kJ.mol-1, la energía libre de Gibbs (kJ.mol-1 y cambio de entropía (J.mol-1K-1, fueron, respectivamente: Ca (II = + 0,07 ± 0,01; - 18,8 ± 0,5, 63,0 ± 2; Cu (II = + 6,24 ± 0,06, - 67,9 ± 0,5, 249 ± 2; Zn (II = + 0,25 ± 0,01, - 49,7 ± 0,5, 167 ± 2 e Al (III = + 6,84 ± 0,45, - 78,2 ± 0,5, 285 ± 2. Los complejos formados son entrópicamente impulsado, desde el punto de vista energético, las interacciones se presentan muy pobres, que pueden ser observadas por los valores positivos del cambio de entalpia. Esto se debe principalmente a la eliminación de las moléculas de agua de hidratación de los iones de metal para la mayor parte de la solución. Con la información actual, podemos concluir que la complejidad del herbicida con el ion de aluminio es más fuerte que con otro cationes.

  20. Aluminum as a risk factor for Alzheimer's disease Aluminio como factor de riesgo para la enfermedad de Alzheimer Alumínio como fator de risco para a doença de Alzheimer

    Directory of Open Access Journals (Sweden)

    Pricilla Costa Ferreira

    2008-02-01

    Full Text Available The purpose of the study was to condense existing scientific evidence about the relation between aluminum (Al exposure and risk for the development of Alzheimer's Disease (AD, evaluating its long-term effects on the population's health. A systematic literature review was carried out in two databases, MEDLINE and LILACS, between 1990 and 2005, using the uniterms: "Aluminum exposure and Alzheimer Disease" and "Aluminum and risk for Alzheimer Disease". After application of the Relevance Test, 34 studies were selected, among which 68% established a relation between Al and AD, 23.5% were inconclusive and 8.5% did not establish a relation between Al and AD. Results showed that Al is associated to several neurophysiologic processes that are responsible for the characteristic degeneration of AD. In spite of existing polemics all over the world about the role of Al as a risk factor for AD, in recent years, scientific evidence has demonstrated that Al is associated with the development of AD.El objetivo del estudio fue condensar la evidencia científica existente entre la exposición al aluminio (Al y el riesgo para el desarrollo de la Enfermedad de Alzheimer (EA, evaluando los efectos para la salud de la población a largo plazo. Una revisión sistemática de la literatura científica existente entre 1990 y 2005, fue realizada en dos bases de datos, MEDLINE y LILACS, utilizando los unitermos: "Aluminium exposure and Alzheimer Disease" y "Aluminium and risk for Alzheimer Disease". Fueron seleccionados 34 trabajos para la investigación, de los cuales 68% establecieron relação entre el Al y la EA, 23,5% no presentaron datos conclusivos y 8,5% no establecieron ninguna relación entre el Al y la EA. A partir de los resultados obtenidos, se verifica que el Al interviene en diversos procesos neurofisiológicos responsables por la degeneración característica de la EA. A pesar de la polémica existente en el médio científico, la evidencia cient

  1. Electrocoagulación aplicada al tratamiento de efluentes generadospor empresas de mantenimiento de motores.

    Directory of Open Access Journals (Sweden)

    Alicia Guevara

    2011-05-01

    Full Text Available La electrocoagulación es una operación que desestabiliza una emulsión y permite altos porcentajes de remoción de demanda química de oxígeno (DQO y turbiedad. En el presente trabajo se evaluó la electrocoagulación como técnica de tratamiento no convencional de efluentes generados por empresas de Mantenimiento de motores y para la evaluación de la operación se midieron los parámetros: DQO, tensoactivos, sólidos suspendidos y totales, turbiedad y concentración de aluminio, cobre y cinc. El efluente estudiado se caracterizó por ser altamente heterogéneo, así la DQO varió entre 10 500 mg/l y 14 700 mg/l. La turbiedad desde 619 NTU a 886 NTU. El rango de tensoactivos desde 86,6 mg/l a 221, 6 mg/l. La concentración inicial de aluminio fue 88 mg/l, de cobre fue 123 mg/l y de cinc fue 13 mg/l. La concentración inicial de sólidos suspendidos fue 340 mg/l y la concentración de sólidos totales fue 10 456 mg/l. En la investigación se establecieron los valores de las variables que influyen en la electrocoagulación para hacerla eficiente. El pH de operación que presenta mejores resultados es 9,7. La intensidad de corriente que se determinó como la más eficiente es de 1,8 A. Con esta intensidad de corriente se tiene una remoción de DQO de 32%, remoción de sólidos suspendidos de 98,3 %, remoción de turbiedad de 97,4 % y remoción de aluminio 88%, de cobre 87% y de cinc de 99%, El tiempo de residencia que requiere la operación es de 60 minutos.

  2. Comportamiento a desgaste de recubrimientos de material compuesto de matriz de aluminio fabricados por proyección térmica

    Directory of Open Access Journals (Sweden)

    Campo, M.

    2007-10-01

    Full Text Available In this work, the wear behaviour of coatings made of aluminium matrix composites reinforced with 20% of SiC particles and manufactured by thermal spray method with oxyacetylene flame has been investigated. The wear behaviour between coatings with uncoated particles and sol-gel silica coated ones heat treated at 500 °C and 725 °C have been compared. The sprayed coatings with silica coated particles are more homogenous and less porous due to increase of wettability by molten aluminium that takes place on coated particles. The microstructure of the sprayed coatings, the wear surfaces and the wear debris have been anlysed using optical microscopy, scanning electron microscopy and microanalysis techniques (EDX. The results show a smaller wear rate, a lower friction coefficient and more reduced loss of mass for the coatings sprayed with particles with sol-gel silica coatings than those made with uncoated particles.

    En este trabajo se ha evaluado el comportamiento a desgaste de recubrimientos de material compuesto reforzado con un 20 % de partículas de SiC fabricados por proyección térmica con llama oxiacetilénica. Se ha comparado el desgaste de los recubrimientos proyectados con partículas sin recubrir y recubiertas con la sílice sol-gel tratada térmicamente a 500 °C y 725 °C. Los recubrimientos proyectados con partículas recubiertas de sílice son más homogéneos y menos porosos debido fundamentalmente al aumento de su mojabilidad por aluminio fundido. La microestructura de los recubrimientos proyectados, de las superficies desgastadas y del material eliminado en los ensayos pin-on-disc se ha analizado por técnicas de microscopía óptica y electrónica de barrido junto a microanálisis EDX. Los resultados obtenidos muestran una menor tasa de desgaste, menor coeficiente de rozamiento y menor pérdida de masa para los recubrimientos proyectados con las partículas con el recubrimiento de sílice sol-gel que para los de las

  3. Reducción del tiempo y de la temperatura de sellado del aluminio anodizado con aditivos orgánicos

    Directory of Open Access Journals (Sweden)

    Bautista, A.

    1998-05-01

    Full Text Available Different sealing processes of anode coatings in aluminium oxide have been industrially used for more than 30 years. In two of the preceeding decades a great effort was realized to reduce costs in the traditional hydrothermal sealing process in deionized boiling water (SHT, a very expensive process due to its endurance and high temperature on which it develops. New sealing procedures are proposed, on which by means of the use of organic additives, the time or the temperature of the SHT is essentially reduced.

    Diferentes procesos de sellado de las capas anódicas de óxido de aluminio se han utilizado industrialmente desde hace más de 30 años. En los dos decenios precedentes se ha realizado un gran esfuerzo para reducir los costes de la operación del sellado hidrotérmico tradicional, en agua desionizada a ebullición (SHT, una operación muy costosa por su duración y la temperatura a la que se desarrolla. Se proponen nuevos procedimientos de sellado en los que, mediante la utilización de aditivos orgánicos, se reduce sustancialmente el tiempo del SHT o la temperatura del mismo.

  4. Autoprotección del aluminio anodizado sin sellar expuesto a la atmósfera

    Directory of Open Access Journals (Sweden)

    Escudero, E.

    2005-04-01

    Full Text Available To confirm or refute the widely held idea that the sealing operation is vital to guarantee the good resistance of anodised aluminium to atmospheric corrosion, unsealed anodised specimens with three different film thicknesses were exposed in 9 atmospheres in Iberoamérica with salinity values of between 3.9 and 684 mg m sup>-2 day-1 of chlorides. Using a wide variety of techniques, from scanning and transmission electron microscopy to direct measurements by gravimetry, and including indirect measurements by electrochemical techniques as well as standard sealing quality control tests, the self-sealing capacity of unsealed anodic coatings during atmospheric exposure is demonstrated. Surprisingly, unlike other types of protective coatings, the quality of anodic films improves with ageing. Keywords

    Para confirmar o rebatir la idea, muy difundida, de que la operación de sellado es imprescindible para garantizar una buena resistencia del aluminio anodizado a la corrosión atmosférica, se expusieron muestras de anodizados sin sellar, de tres espesores diferentes, en 9 atmósferas de Iberoamérica, con salinidades comprendidas entre 3,9 y 684 mg m-2 d-1 de cloruros. Por las más variadas técnicas, desde la microscopía electrónica de barrido o transmisión a la medida directa por gravimetría, pasando por los ensayos normalizados de control de calidad del sellado y la medida indirecta por técnicas electroquímicas, se demuestra la capacidad de autosellado, durante la exposición a la atmósfera, de los recubrimientos anódicos sin sellar. Sorprendentemente, a diferencia de lo que ocurre en recubrimientos protectores de otra naturaleza, la calidad de los anodizados mejora con el envejecimiento.

  5. Modelación del perfil de soldadura y de la cavidad de vapor en la aleación de aluminio 5182 soldada con láser. // Welding profile and steam cavity modelation in aluminum 5182 alloy welded with laser.

    Directory of Open Access Journals (Sweden)

    M. Pastor

    2002-09-01

    Full Text Available El presente trabajo incursiona en el desarrollo de modelos para predecir la forma de la cavidad de vapor y el perfil de laaleación de aluminio 5182 con soldadura láser, para lo cual ha sido empleado el paquete profesional de elementos finitosCOSMOS/M. La modelación de la soldadura ha sido realizada considerando como variable el grado de desenfoque del hazde láser, considerando el flujo de calor según un modelo Gaussiano, con un coeficiente de absorción de 0.24 para lacondición de haz enfocado y 0.16 para las condiciones de desenfoque negativo y positivo. La validez de los resultadosobtenidos se comprobó mediante los resultados obtenidos en pruebas experimentales.Palabras claves: Aleaciones de aluminio, láser de Nd:YAG._______________________________________________________________________AbstractThe purpose of this research is the study of laser welding process for the 5182 aluminum alloys and the development ofmodels by means of the COSMOS/M package, in order to predict the shape of the steam cavity and the weldingtemperatures profile. Modeling has been done considering the degree of defocusing. The heat flow applied on the modelswas a Gauss flow, with a coefficient of absorption of 0.24 for the condition of the focused face and 0.16 for the conditionsof negative and positive defocusing. The validity of the models has been demonstrated comparing their results with thoseobtained by experimental tests.Key words: Aluminum alloys, Nd: YAG laser.

  6. Estudio Comparativo de Sulfato de Aluminio y Semillas de Moringa oleifera para la Depuración de Aguas con Baja Turbiedad Comparative Study of Aluminum Sulfate and Moringa oleifera seeds as Coagulants in the Clarification of Water with Low Turbidity

    OpenAIRE

    Patrícia G.S Lédo; Raquel F.S Lima; João B.A Paulo; Marco A.C Duarte

    2009-01-01

    El presente trabajo tiene como objetivo investigar la eficiencia de dos coagulantes, el sulfato de aluminio y semillas de Moringa oleifera, para remoción de turbiedad en muestras del agua provenientes de la Laguna de Jiqui, estado del Rio Grande do Norte, Natal-Brasil. Las dosificaciones y pH de los coagulantes fueron variados entre límites establecidos. Se realizaron pruebas, en tubos de ensayo Jar-Test y medidas de movilidad electroforética para determinar el potencial Zeta y para determina...

  7. Caracterización superficial de nuevos pre-tratamientos a base de silanos aplicados sobre aluminio

    Directory of Open Access Journals (Sweden)

    Gener, M.

    2005-12-01

    Full Text Available Silane- based pre-treatments are an alternative process for the chrome-based corrosionpreventive commercial pre-treatments, without salubrity problems and that in initial exploratory studies have yielded promising results regarding corrosion protection and adhesion promotion. In the framework of the research about the anticorrosive capacity of these compounds that it's being undertaken for different silane and substrates, some preliminary results are presented in this paper. Specifically, the results of the surface characterisation through SEM-EDS (Scanning Electron Microscopy and XPS (X-Ray Photoelectron Spectroscopy for two silanes with different functional groups (3-aminopropyltriethoxysilane or γ-APS and 3-glycidyloxypropyltrimethoxysilane or γ-GPS, prepared at different pH and applied as primers on an aluminium substrate, are discussed.

    Un proceso alternativo a los pre-tratamientos comerciales anticorrosivos a base de cromo, sin problemas de salubridad y que en estudios exploratorios iniciales ha dado resultados prometedores en cuanto a la protección frente a la corrosión y la mejora de la adherencia, son los pre-tratamientos a base de silanos. En el marco de la investigación sobre la capacidad anticorrosiva de estos compuestos que se está realizando para diferentes silanos y substratos, se presentan en este artículo algunos de los resultados preliminares. En concreto, se discuten los resultados de la caracterización superficial mediante técnicas de SEM-EDS (Scanning Electron Microscopy y XPS (X-Ray Photoelectron Spectroscopy para dos silanos con distintos grupos funcionales (3-aminopropiltrietoxisilano o γ-APS y 3-glicidiloxipropiltrimetoxisilano o γ-GPS, preparados a distintos pH y aplicados como imprimación sobre un substrato de aluminio.

  8. Aleaciones cuasicristalinas Al93Fe3Cr2Ti2

    Directory of Open Access Journals (Sweden)

    García-Escorial, Asunción

    2015-12-01

    Full Text Available Aluminium alloy powder having a nominal composition of Al93Fe3Cr2Ti2 (at% has been prepared using gas atomisation. The atomised powder present a microstructure of an aluminium matrix reinforced with a spherical quasicrystalline icosahedral phase, in the range of nanometre in size. The powder was consolidated into bars using warm extrusion. The microstructure of the extruded bars retains the quasicrystalline microstructure and the bars present outstanding mechanical properties, i.e. proof stress of 280 MPa at 300 °C. Upon heating the microstructure evolves towards the equilibrium. The thermal evolution was investigated by means of x-ray diffraction, differential scanning calorimeter, scanning electron microscopy and transmission electron microscopy. According to these observations a transformation in two steps is proposed. A first step consists in the decomposition of the supersaturated solid solution of the matrix and the quasicrystals, and a second step in the transformation of the quasicrystals into the equilibrium phases.Se ha obtenido por atomización por gas polvo de la aleación Al93Fe3Cr2Ti2 (at%. Este polvo presenta una microestructura de una matriz de aluminio reforzada por precipitados icosaédricos de tamaño nanométrico. El polvo fue consolidado por extrusión en forma de barras cilíndricas. La microestructura de las barras retiene la microestructura cuasicristalina de las partículas de polvo. El material consolidado presenta propiedades mecánicas prometedoras, como un límite elástico de 280 MPA a 300 °C. Con los tratamientos térmicos, la microestructura evoluciona hacia el equilibrio. Esta evolución se estudia por difracción de rayos x, calorimetría diferencial de barrido, microscopías electrónicas de barrido y de transmisión. A la luz de los resultados obtenidos se propone que la transformación de las fases con el tiempo de tratamiento térmico ocurre en dos pasos. Primeramente, tiene lugar la descomposición de la

  9. Microestructura y propiedades mecánicas de materiales compuestos de matriz Al-Mg-Si-Cu reforzada con AlNp, procesados por extrusión de polvos

    Directory of Open Access Journals (Sweden)

    Ortiz, José Luis

    2000-10-01

    Full Text Available This article presents an experimental investigation on the structure and mechanical properties of an Al-Mg-Si-Cu P/M alloy reinforced with 5 %, 10 % and 15 % aluminum nitride, produced by extrusión of cold compacted powders mixtures. Mechanical properties in "as extruded" and T6 conditions are compared. Differential Scanning Calorimetry and Dilatometric analysis were conducted to gain further insight into the precipitation process of these materials. Low cost 6061Al/AlNp composites can be produced with rare and small porosity by extrusión of cold compacted shapes without canning. The mechanical properties of the MMCs obtained by this process have limitations for high particles fractions because of clustering effects. All materials are always harder than the matrix and shows a similar behavior during aging processes but kinetics is changed. Potential applications of dilatometric techniques in the aging investigations of aluminum alloys and aluminum matrix composites have been established.

    Se presenta una investigación experimental sobre la relación entre la estructura y las propiedades mecánicas de materiales obtenidos mediante la extrusión en caliente de preformas de polvos compactados en frío y cuya matriz es una aleación Al-Mg-Si-Cu con composición cercana a la AA6061, reforzada con tres proporciones diferentes (5, 10 y 15 % en volumen de partículas de AlN. Se utilizó Calorimetría Diferencial de Barrido y Dilatometría sobre las muestras solubilizadas y templadas para complementar el estudio del efecto de las partículas sobre el envejecimiento de la aleación base. Se establece que es posible producir, a bajo costo, materiales compuestos de matriz metálica, MMCs, de matriz de aleación AA6061 reforzada con partículas de AlN con baja porosidad y buenas propiedades mecánicas, mediante la extrusión de mezclas de polvos compactados en frío, sin necesidad de enlatado. Sin embargo, las aglomeraciones de partículas, para

  10. Comportamiento a tracción a temperaturas ambiente y elevadas de nuevos composites basados en aleaciones hipereutécticas de Al-Si

    Directory of Open Access Journals (Sweden)

    Valer, J.

    1997-02-01

    Full Text Available This work shows the improvement obtained on tensile stress at room and high temperatures of hypereutectic Al-Si alloys. These alloys are produced by a combination of spray-forming, extrusión and thixoforming process, in comparison with conventional casting alloys. Al-25%Si-5%Cu, Al- 25%Si-5%Cu-2%Mg and Al-30%Si-5%Cu alloys have been studied relating their microstructural parameters with tensile stress obtained and comparing them with conventional Al-20%Si, Al-36%Si and Al-50%Si alloys. Al-25%Si-5%Cu alloy was tested before and after semi-solid forming, in order to distinguish the different behaviour of this alloy due to the different microstructure. The properties obtained with these alloys were also related to Al-SiC composites formed by similar processes.

    En este trabajo se muestra la mejora obtenida en la resistencia a la tracción a temperatura ambiente y a elevadas temperaturas de aleaciones hipereutécticas de Al-Si producidas por una combinación de un proceso de solidificación rápida y del conformado en estado semisólido, en comparación con aleaciones obtenidas por procedimientos convencionales de inyección en estado líquido. Se han estudiado las aleaciones Al-25%Si-5%Cu, Al-25%Si-5%Cu-2%Mg y Al-30%Si-5%Cu, relacionando sus parámetros microestructurales con las resistencias a tracción obtenidas, y se han comparado con las aleaciones binarias Al-20%Si, Al-36%Si y Al-50%Si. La aleación Al-25%Si-5%Cu se ha ensayado antes y después del conformado en estado semisólido, lo que ha permitido conocer la diferencia en el comportamiento de la aleación como consecuencia de la distinta microestructura. También se comparan las propiedades obtenidas en estas aleaciones con las que presentan composites de aleaciones de aluminio reforzados con partículas de SiC y procesados por métodos similares.

  11. Influencia del medio de ensayo y dirección de aplicación de la carga en el comportamiento a corrosión bajo tensiones de la aleación de aluminio 7075

    Directory of Open Access Journals (Sweden)

    Badía, J. M.

    2004-12-01

    Full Text Available The goal of this work is to prove the validity of using synthetic sea water as an alternative method instead of the NaCl solution used in stress corrosion crack growth tests in aluminium alloys, according to ASTM G 44. Several samples of 7075 alloy have been tested in different conditions and directions in both environments, which can be considered as equivalent. Only the samples tested in thickness direction have shown crack growth during the test. The use of sea water entails a great advantage in practice, by less superficial alteration, and lets therefore a much more reliable measure of the crack.

    El objetivo de este trabajo es comprobar la validez del empleo de agua de mar sintética como método alternativo a la solución de NaCl utilizada en los ensayos de crecimiento de grieta por corrosión bajo tensiones en aleaciones de aluminio, según la norma ASTM G- 44. Para ello, se ha procedido al ensayo de muestras de aleación 7075 en diferentes estados de tratamiento y con distintas orientaciones en ambos medios, comprobándose que pueden considerarse equivalentes. Sólo las probetas ensayadas en la dirección del espesor mostraron crecimiento de grieta durante los ensayos. La utilización del agua de mar representa una gran ventaja práctica ya que altera mucho menos la superficie de las muestras y permite, por tanto, una medida mucho más fiable de la grieta durante el ensayo.

  12. Alternativa de protección contra la corrosión del acero AISI 310S mediante recubrimiento de aluminio bajo condiciones de platos separadores en celdas de combustible de carbonatos fundidos

    Directory of Open Access Journals (Sweden)

    R. Orozco-Cruz

    2016-01-01

    Full Text Available Introducción: La celda de combustible de carbonatos fundidos (MCFC, por sus siglas en inglés convencional opera a 650°C. Consiste de un cátodo de NiO poroso y litiado, una mezcla eutéctica de carbonato de litio (Li2CO3 y carbonato de potasio (K2CO3 fundido en una matriz electrolitica de óxido de aluminio litiado (LiAlO2 y un ánodo poroso de Ni. Los platos separadores entre cada celda presentan problemas de corrosión. Ante eso, un acero inoxidable AISI 310S con recubrimiento fue estudiado en condiciones de un plato separador en una MCFC. Método: Se utilizó un acero inoxidable AISI 310S como sustrato (muestra A, aplicándole un recubrimiento de Al con (B y sin tratamiento térmico (C. Fueron expuestos en carbonatos fundidos (62 mol% Li2CO3 -38 mol% K2CO3 a 650 °C en crisoles de alúmina. El comportamiento electroquímico fue estudiado mediante la técnica de Espectroscopía de Impedancia Electroquimica (EIS. Para el análisis de los diagramas de impedancia, se utilizó el software de simulación “Boukamp Equivalent Circuit”. La sección transversal de las muestras corroídas fue caracterizada mediante Microscopía Electrónica de Barrido (SEM, por sus siglas en inglés y los productos formados por Difracción de rayos X (XRD, por sus siglas en inglés. Resultados: Los diagramas de EIS presentan aumentos y disminuciones en los semicírculos formados a altas frecuencias indicativo de disolución de la capa externa, aumento y disminución de la resistencia de esta última así como el posible rompimiento de ella. La técnica de XRD presentó fases LiFeO2, LiCrO2, -LiAlO2 y -LiAlO2 así como fases intermetálicas para las distintas condiciones de la muestra. De la misma manera, los análisis de SEM presentaron los espesores de cada una de las capas formadas. Discusión o Conclusión: En la muestra A, se formaron capas de LiFeO2 y LiCrO2 después de 200 horas de exposición. La capa de LiCrO2 aumenta por la difusión de Li hacia el

  13. Estudio del proceso de laminación de módulos fotovoltaicos con materiales alternativos

    OpenAIRE

    Murillo Larrey, Ana

    2016-01-01

    Este Trabajo Fin de Grado (TFG) desarrollará el proceso de laminación de módulos fotovoltaicos (FV) utilizando materiales alternativos a los de los módulos convencionales. Los materiales alternativos son el policarbonato (PC) y un entramado estructural, los cuales sustituyen al vidrio y al marco de aluminio. El objetivo de la utilización de estos materiales es la construcción de un módulo ligero y adaptable a diferentes superficies para facilitar su uso en integración arquitect...

  14. Estructura y textura de la fase Al3CaZn en una chapa laminada de la aleación superplástica Al-5 % Ca-5 % Zn

    Directory of Open Access Journals (Sweden)

    Pérez-Pardo, M. T.

    1998-05-01

    Full Text Available The structure of the intermetallic phase Al3CaZn present in the superplastic sheet alloy Al-5 % Ca-5 % Zn has been determined by means of x-ray diffraction (XRD and electrón diffraction (TEM. Also, the texture of this phase has been studied by means of pole figures and the orientation distribution function (ODF. The Al-5 % Ca-5 % Zn alloy is formed by a fine grained aluminum matrix (d ≈ 2-3 μm and 20 % vol. of Al3CaZn in the form of round-shaped particles with 0.2-0.5 μm diameter. This alloy undergoes superplastic behavior in a wide range of strain rates and temperatures. It has been found in this work that the structure of the second phase is body-centered tetragonal, with lattice parameters a = b = 0.422 nm and c = 1.131 nm. The texture of the alloy is formed by the fiber <001>, i.e., the crystallites are oriented preferentially with the c-axis perpendicular to the rolling plane. The texture sharpens after severe annealings.

    En este trabajo se ha determinado la estructura de la fase Al3CaZn, presente en una chapa laminada de la aleación Al-5 % Ca-5 % Zn, mediante técnicas de difracción de rayos X (DRX y difracción de electrones (MET. Además, se ha estudiado su textura mediante figuras de polos y la función de distribución de orientaciones (FDO. La aleación Al-5 % Ca-5 % Zn objeto de este estudio consta de una matriz de aluminio de grano fino (d ≈ 2-3 μm y un 20 % vol. de la fase Al3CaZn. Esta segunda fase está presente en el material de partida en forma de partículas esferoidales de 0,2 - 0,5 μm de diámetro. La aleación presenta un comportamiento superplástico en un amplio intervalo tanto de velocidades de deformación como de temperaturas. Se ha encontrado que la fase Al3CaZn posee una estructura tetragonal centrada, con parámetros de red a = b= 0,422 nm y c = 1,131 nm. Presenta, además, una textura de fibra <001>, en la

  15. Validación de un método analítico para la determinación cuantitativa de parabenos en el gel de hidróxido de aluminio Validation of an analytical method for the quantitative determination of parabens in aluminum hydroxide gel

    OpenAIRE

    Ernesto Benítez Hechavarría; Ciro Labrada Estrada; Enriqueta Martínez Martínez; Odalis Tamayo Fuentes; Esther Díaz Pérez

    2006-01-01

    Se realizó la valoración prospectiva de un método desarrollado para la cuantificación de metil y de propil parabeno en el gel de hidróxido de aluminio mediante cromatografía líquida de alta resolución en fase reversa, con columna RP18 (25* 0,4 cm) y detector UV-Visible a 254 nm. Se evaluaron los parámetros especificidad, linealidad, precisión, exactitud, y adecuación cromatográfica. Los resultados obtenidos mostraron que el método cumple con las especificaciones establecidas para cada parámet...

  16. Impedance spectroscopy evolution upon sintering of Al-rich anodising sludge-based extruded bodies

    Directory of Open Access Journals (Sweden)

    Ribeiro, M. J.

    2006-08-01

    Full Text Available Alumina based ceramic materials, containing Al-rich sludge as the major component, were processed by extrusion. The sludge derived from the wastewater treatment of aluminium anodising industrial process. Long rods were produced using a vacuum screw extruder, by a careful control of all relevant processing parameters. Then, thick discs were obtained by cutting dried selected rods, to be tested as probes for sintering-dependent electrical properties. The sintering process was followed by performing common dilatometric/thermal analyses but the evolution of electrical conductivity, estimated by impedance spectroscopy (IS, was also used for this purpose. Results show that sintering-dependent morphological evolution up to 1300ºC strongly affects the electrical behaviour of samples, and as a consequence IS seems to be a useful technique to follow the firing process.

    Los materiales cerámicos basados en alúmina, conteniendo barros ricos en Al como componente mayoritario fueron procesados por extrusión. Los barros empleados provienen de tratamientos de lavado de residuos de un proceso industrial de anodizado de aluminio. Se produjeron varillas empleando un extrusor de tornillo en vacío con control de todos los parámetros relevantes del proceso. A partir de varillas seleccionadas, se obtuvieron por corte en seco discos cerámicos para evaluar la dependencia de la sinterización y las propiedades eléctricas. El proceso de sinterización se siguió mediante ensayos dilatométricos y análisis térmicos, junto con la evolución de la conductividad eléctrica mediante espectroscopia de impedancia. Los resultados mostraron la evolución de la sinterización y la dependencia morfológica hasta 1300ºC, que afecta fuertemente a la respuesta eléctrica y como consecuencia la espectroscopia de impedancia parece ser una técnica útil en el seguimiento de los procesos de cocción.

  17. Estrategias de enraizamiento de genotipos Brachiaria en suelos ácidos y de baja fertilidad en Colombia

    Directory of Open Access Journals (Sweden)

    Jaumer Ricaurte

    2007-09-01

    Full Text Available En un Haplustox de los Llanos Orientales de Colombia se evaluaron durante 41 meses 6 genotipos de Brachiaria con resistencia variable a niveles altos de Al+3 en dos niveles de nutrientes. Los genotipos con resistencia media y alta mantuvieron altas producciones de biomasa aérea en los primeros meses, decrecieron a valores medios y estables hacia los 21 meses. La producción de biomasa y longitud de raíces en los genotipos de Brachiaria y especies de sabana nativa fue mayor en época lluviosa, con alta producción en los primeros 5 cm del perfil de suelo. Las gramíneas de la sabana nativa y B. decumbens CIAT 606 (altamente resistente a Al+3 generaron raíces finas y menor biomasa de raíces. Durante la época seca los genotipos de Brachiaria con resistencia media y alta a aluminio generaron raíces más profundas que la sabana nativa. La época seca indujo una producción de longitud y biomasa de raíces proporcionalmente más profundas que la lluviosa, tanto en genotipos de Brachiaria con resistencia media y alta a aluminio como en especies de la sabana nativa.

  18. Estudio del uso del lodo residual de la empresa Extralum S. A. como material alternativo en la fabricación de cementos especiales

    Directory of Open Access Journals (Sweden)

    Maricruz Vargas Camareno

    2006-05-01

    Full Text Available La empresa Extralum S. A. es una industria dedicada a la manufactura de aluminio crudo, anodizado y laqueado para uso arquitectónico. En su proceso de tratamiento de aguas residuales, genera alrededor de 90 toneladas al mes de un sólido blanco, el cual ya ha sido caracterizado, y se encontró que es rico en óxidos de aluminio hidratados; en la actualidad este material es desechado en rellenos sanitarios. Considerando que el cemento es un producto con demanda creciente, que para su producción requiere altos consumos de energía, cualquier avance que se realice para disminuir el consumo energético,tiene importantes beneficios económicos y ambientales. Dentro de las soluciones posibles, se encuentra la utilización de materiales alternativos que pueden ser utilizados como materias primas o materiales cementosos de reemplazo parcial o total del cemento Pórtland. Las pruebas realizadas a las diferentes mezclas demuestran que el lodo incorporado al cemento como relleno, modifica sus características iniciales, acelerando los tiempos de fragua, aumentando la porosidad del material, condición que afectó, negativamente, la resistencia del cemento, pero aumentó su capacidad aislante.

  19. Caracterización mecánica de recubrimientos de aluminio por CVD-FBR sobre aceros inoxidables y resistencia a la oxidación en vapor de agua

    Directory of Open Access Journals (Sweden)

    Diego Pérez-Muñoz

    2015-09-01

    Full Text Available Los recubrimientos de aluminio depositados sobre el acero inoxidable austenítico AISI 317 por Deposición Química de Vapor en Lecho Fluidizado (CVD-FBR presentan a altas temperaturas una reducción de la velocidad de corrosión de más de 80 veces. Se realizó la caracterización mecánica de los recubrimientos por medio de microdureza, nanoindentación, para conocer cómo se vieron afectas las propiedades mecánicas (en especial la dureza y el módulo de Young del recubrimiento y del sustrato luego de ser sometidos a la oxidación a alta temperatura. También se hicieron análisis por medio de Microscopia Electrónica de Barrido (MEB, para observar los cambios microestructurales, y de Microscopia de Fuerza Atómica (MFA, para observar cómo varía la topografía y el gradiente de rugosidad en función de la distancia recorrida por la punta del cantiléver durante los barridos.

  20. Biochemical analysis of the Hormoconis resinae fungal mycelium in the corrosion of aeronautical aluminium alloys

    Directory of Open Access Journals (Sweden)

    Araya, R.

    2007-06-01

    Full Text Available Biochemical analyses of the Hormoconis resinae fungal mycelium would explain behaviour differences of corrosive and non-corrosive strains on Al and its aeronautical alloys. In previous works its aggressiveness had been studied through SEM-EDX surface analysis, electrochemical techniques and immersion testing. In this paper separation of the proteins of the mycelium produced by a non-corrosive strain and its culture along three generations was performed. Cultures were prepared in batch in the presence and absence of pure Al and AA 2024, AA 7005 and AA 7075 alloys. The mycelia grown throughout the three generations increasingly
    recovered usual characteristics at the third replication, included their corrosiveness on Al and its alloys previously shown by all our strains. Amongst the bio-molecule fractions isolated and analysed during this preliminary study only the proteins revealed changes with the generation grown. When this fungal strain was cultured in the presence of alloy metal sheets electrophoresis of the protean fraction was correlative with the distinct mycelia behaviour observed, including corrosiveness on Al and its alloys.

    Las diferencias entre el comportamiento corrosivo y no corrosivo de una cepa del hongo Hormoconis resinae sobre aluminio y sus aleaciones aeronáuticas se explicarían a través de análisis bioquímicos del micelio. En trabajos previos, el comportamiento corrosivo se estudió mediante análisis de superficie SEM-EDX, técnicas electroquímicas y ensayos de inmersión. En este trabajo, se llevó a cabo la separación de proteínas del micelio producido por una cepa que perdió su corrosividad y su cultivo a través de tres generaciones. Cultivos en batch, en presencia y ausencia de aluminio y sus aleaciones AA 2024, AA 7005 y AA 7075, a través de tres generaciones del micelio crecido, fueron recuperando sus características, incluida su habitual corrosividad, en la tercera replicaci

  1. Corrosion and protection of metals in the rural atmosphere of "El Pardo" Spain (PATINA / CYTED project

    Directory of Open Access Journals (Sweden)

    Simancas, J.

    2003-12-01

    Full Text Available Atmospheric corrosion tests of metallic and organic coatings on steel, zinc and aluminium have been conducted in "El Pardo" (Spain as part of the PATINA/CYTED project "Anticorrosive Protection of Metals in the Atmosphere". This is a rural atmosphere with the following ISO corrosivity categories: C2 (Fe, C2 (Zn, C3 (Cu and Cl (Al. Its average temperature and relative humidity is 13 °C and 62.8 %, respectively, and it has low SO2 and Cl- contents. Results of 42 months exposure are discussed. Atmospheric exposure tests were carried out for the following types of coatings: conventional paint coatings for steel and hot-dip galvanized steel (group 1, new painting technologies for steel and galvanized steel (group 2, zinc-base metallic coatings (group 3, aluminium-base metallic coatings (group 4, coatings on aluminium (group 5 and coil-coatings on steel, hot-dip galvanized steel and 55 % Al-Zn coated steel (group 6.

    Como parte del proyecto PATINA/CYTED "Protección anticorrosiva de metales en la atmósfera" se han llevado a cabo en la estación de ensayo de "El Pardo" (España, ensayos de corrosión atmosférica de recubrimientos metálicos y orgánicos sobre acero, zinc y aluminio. Se trata de una atmósfera rural según la clasificación ISO de grado de corrosividad: C2 (Fe, C2 (Zn, C3 (Cu y Cl (Al. La temperatura y humedad relativa media es de 13 °C y 62,8 %, respectivamente, y tiene bajos contenidos de SO2 y Cl-. Se discuten los resultados obtenidos después de 42 meses de exposición. Los ensayos de corrosión atmosférica se llevaron a cabo para tres tipos de recubrimientos: recubrimientos de pintura convencional sobre acero y acero zincado (grupo 1, nuevas tecnologías en pinturas para acero y acero galvanizado (grupo 2, recubrimientos metálicos base zinc (grupo 3, recubrimientos metálicos base aluminio (grupo 4, recubrimientos sobre aluminio (grupo 5 y recubrimientos de banda en continuo

  2. Evaluación de recubrimientos a base de zinc en la atmosfera industrial de la refineria estatal Esmeraldas

    OpenAIRE

    Huaman M, M.; Peña E., J.

    2009-01-01

    El estudio del comportamiento frente a la corrosión atmosférica, de recubrimientos de zinc sobre acero al carbón bajo diferentes condiciones ambientale. En este proyecto se pretende conocer y evaluar el comportamiento del acero galvanizado en caliente (dicontinuo, chapa galvanizada en caliente (continuo senzimir), chapa galvanizada en continuo con aleación de zinc 5% aluminio (galfan), chapa zincada por procedimiento ewlectrolitico (galvanizado en frío) y acero metalizado con zinc en diversas...

  3. Comportamiento a fractura de la aleación 6061 reforzada con alúmina

    Directory of Open Access Journals (Sweden)

    Forn, A.

    2004-04-01

    Full Text Available The properties of the cast aluminium alloys 6061/(20%Al2O3p are studied. This material is obtained by Duralcan procedure after being submitted to an extrusion and forging process. These materials are submitted to T6 heat treatments in order to study their effect on mechanical properties. In this work the matrix characteristics are compared with the reinforced material in different production stages, using an optical and electronic microscopy, EDS, tensile, fatigue and ultramicrohardness tests. The mechanical properties indicate that the extruded reinforced material presents ultimate tensile strength values lower than the alloy 6061 under the same conditions, and this is related to the presence of spinel in the interface matrix-reinforcement. The fracture mechanisms are established by static and dynamic tensions in different cases, studying the possible interactions matrix-reinforcement and their repercussion in the mechanical behaviour of the alloy.

    Se estudian las propiedades de las aleaciones de aluminio 6061/(20%Al2O3p obtenidas por colada y conformadas posteriormente por extrusión y forja. Estos materiales son sometidos a tratamientos térmicos de envejecimiento (T6 para estudiar su efecto en las propiedades mecánicas. En este trabajo se comparan las características de la matriz con las del material reforzado en las distintas etapas de producción utilizando técnicas de microscopía óptica y electrónica, EDS y ensayos de tracción, fatiga y ultramicroindentación. Los ensayos mecánicos indican que el material compuesto extruido presenta valores de resistencia mecánica más bajos que la aleación 6061 tratada en las mismas condiciones y ello se relaciona con la presencia de espinela en la interfase alúmina-matriz. Se establecen los mecanismos de fractura por tensiones estáticas y dinámicas en los distintos casos, estudiando las posibles interacciones matriz

  4. Modificación superficial de aleaciones de base aluminio (anodizadas y no anodizadas mediante recubrimientos de sílice

    Directory of Open Access Journals (Sweden)

    García-Heras, M.

    2004-04-01

    Full Text Available Transparent and colourless silica coatings were deposited on anodising and non-anodising substrates of aluminium-base alloys (series 6063. Coatings were prepared by soLgel (dipping method from a silica alkoxide and a mixture of both silica alkoxide and silica alkylalkoxide. Preparations were optimised from viscosity, density, surface tension, and contact angle measurements. Densification was carried out at 60 and 120 °C. Reflectance attenuation of coated samples was analysed by UV-VIS-NIR spectroscopy. The results indicated that -10 % of attenuation is reached. Durability and resistance against degradation tests of the metal/coating system were undertaken by immersion into aqueous solutions. Electrochemical impedance measurements and potential corrosion of the metallic substrate for variable times were performed.

    Se han depositado recubrimientos transparentes e incoloros de sílice sobre sustratos anodizados y no anodizados de aleaciones de base aluminio (serie 6063. Los recubrimientos se prepararon por sol-gel (inmersión-extracción a partir de un alcóxido de silicio y de una mezcla de alcóxido y alquilalcóxido de silicio. La optimización de las fonnulaciones se basó en medidas de viscosidad, densidad, tensión superficial y ángulo de contacto. La densificación se llevó a cabo a 60 y 120 °C. La atenuación de la reflectancia luminosa de las muestras recubiertas se analizó por espectroscopia UV-VIS-IRP. Los resultados indicaron que se alcanza casi un 10 % de atenuación. Los ensayos de durabilidad y resistencia a la degradación del sistema metal/recubrimiento se realizaron por inmersión en disoluciones acuosas, aplicando medidas de impedancia electroquímica y del potencial de corrosión del sustrato metálico, para tiempos variables.

  5. PROCEDIMIENTOS POST-COSECHA Y CALIDAD POST-EMBARQUE DE CAÑAS DE Dracaena marginata PARA EXPORTACIÓN

    Directory of Open Access Journals (Sweden)

    Mar\\u00EDa Isabel Gonz\\u00E1lez-Lutz

    2011-01-01

    Full Text Available Con el objetivo de determinar el efecto de diferentes tratamientos pre-empaque, sobre la calidad final de cañas de Dracaena marginata para exportación, se realizó una simulación del embarque, en época lluviosa en La Virgen de Sarapiquí, Heredia, Costa Ri ca, durante los meses de mayo a julio del 2005. Se evaluó el daño en raíces y hojas de Dracaena marginata de los siguie ntes tratamie ntos: planta con el follaje mojado vs follaje seco, plantas hidratadas previo al empaque vs plantas sin hidratar, plantas con tratamiento de cera al follaje vs plantas sin cera, plantas con tratamie nto con citoquininas antes de la cosecha vs plantas sin tratamie nto con citoquininas, plantas a las que no se les retira la cobertura con hojas de aluminio en el acodo antes de tapar con el plástico negroplata vs plantas a las que sí se les retira esta cobertura previo a este proceso. Humedecer estas antes de empacarlas produjo menores daños en las raíces. Hidratar las plantas, previo al empaque, incrementó el número de hojas quemadas. Colocar cera en el follaje, incrementó significativamente el número de hojas desprendidas y podridas. La aplicación de citoquininas previo a la cosecha y humedecer el follaje antes del empaque, mejoró su condición al compararlo con el testigo. No hubo diferencia en los daños en las raíces entre dejar o quitar la cobertura de hojas de aluminio en el acodo.

  6. Influencia de algunos factores sobre la calidad del anodizado de piezas de aluminio para la construcción. // Influence of some factors over the quality of anodizing process of aluminum articles.

    Directory of Open Access Journals (Sweden)

    J. A. Pérez García

    2004-01-01

    Full Text Available Ya ha sido establecido que de todos los factores que están presentes en el proceso de anodizado, hay tres que tienen la mayorpreponderancia: el tratamiento previo de la superficie a anodizar, el color a aplicar y el espesor de la capa anodizada. A su vez, elprimero de ellos es el que mayor influencia presenta. En este trabajo se presentan los resultados cuantitativos de la influencia deestos factores sobre la calidad de la superficie anodizada, expresada en función de los parámetros Ra , Ry y Rq de la superficieanodizada.Palabras claves: Aluminio, anodizado, calidad._____________________________________________________________________________AbstractIt has been established that there are three factors with the most relevance in the anodizing process: Previous surfacetreatment, color and thickness of the anodized layer. Besides, the influence of the first of them is several times moreimportant than the influence of the others. This paper presents the quantitative study of the influence of these factors overthe quality of the anodized surface, expressed in terms of parameters Ra, Ry and Rq.Key words: Aluminum, anodizing process, quality.

  7. Electrochemical noise evaluation of anodized aluminum. Comparative study against corrosion behaviour in the atmosphere

    Directory of Open Access Journals (Sweden)

    Betancourt, N.

    2003-12-01

    Full Text Available The present work reports the evaluation of aluminum and anodized aluminum by electrochemical noise, as a part of the PATINA/CYTED project of the working group Nº 5. A visual examination is also made. The samples were exposed at several Ibero-American atmospheres up to 2 years of exposure. Different thickness of anodized aluminum were evaluated. The electrochemical potential noise of the 5 μm unexposed sample (pattern showed a different behaviour to that showed by the other anodized specimens. This could be due to a slower sealed of the samples of higher thickness. The same behaviour was observed on the samples exposed at the rural station El Pardo. According to the visual examination, the samples of bare aluminum and those of anodized 5 μm thickness were the most affected by pitting corrosion in the highly polluted atmospheres. A good correlation between corrosion behaviour determined by visual examination and EN was obtained.

    Como parte de las investigaciones de la Red PATINA el grupo de trabajo Nº 5 dedicó su atención al comportamiento del aluminio desnudo y anodizado con diferentes espesores en diferentes atmósferas de Iberoamérica. En el presente trabajo se presenta una evaluación de patrones de aluminio 99,5 % de pureza desnudo y anodizado con espesores de 15 y 25 μm, mediante ruido electroquímico. Los resultados obtenidos se comparan con el comportamiento determinado en diferentes atmósferas durante un período de 2 años. El ruido de voltaje del patrón de 5 μm de espesor presenta un comportamiento diferente al de los restantes espesores, lo que coincide con una mayor susceptibilidad a la corrosión picadura de este primer anodizado. Se reportan también algunas diferencias en el ruido de corriente. Se concluye que mediante la utilización del ruido electroquímico es posible caracterizar el aluminio con respecto a su sensibilidad a la corrosión picadura en condiciones atmosféricas.

  8. Corrosion behavior of Fe3Al intermetallics with addition of lithium, cerium and nickel in 2.5 % SO2+N2 at 900 °C

    Directory of Open Access Journals (Sweden)

    González-Rodríguez, J. G.

    2012-12-01

    Full Text Available The corrosion behavior of Fe3Al-type intermetallic alloys with addition of 1 at. % cerium, lithium and nickel at high temperature has been studied. The various alloys were exposed to an environment composed of 2.5 % SO2+N2 at 900 °C for 48 h. For all the intermetallic tested, the corrosion kinetics showed a parabolic behavior. The alloy, which showed less corrosion rate, was the Fe3AlNi alloy, being Fe3AlCeLi the alloy with the highest corrosion rate. For the various alloys, energy dispersive X-ray spectroscopy analysis, EDS, on the developed scale only detected aluminum, oxygen, and traces of iron and cerium, suggesting the formation of alumina as main component. The intermetallic alloys showed oxide cracking and spalling. The intermetallic chemical composition played an important role in defining the oxide scale morphology and the extent of damage.Se estudió el comportamiento a la corrosión a alta temperatura de intermetálicos tipo Fe3Al con adición de 1at. % de cerio, litio y níquel. Las diferentes aleaciones fueron expuestas bajo un ambiente compuesto de 2,5 % SO2+N2 a 900 °C durante 48 h. Para todos los intermetálicos ensayados, la cinética de corrosión presentó un comportamiento parabólico. La aleación que mostró la menor velocidad de corrosión fue el intermetálico Fe3AlNi, siendo el intermetálico Fe3AlCeLi el de mayor velocidad de corrosión. Los análisis mediante espectroscopía de dispersión de rayos X, EDS, sobre la costra formada identificaron únicamente aluminio, oxígeno y trazas de hierro y cerio, lo que sugiere la formación de alúmina como el componente principal. Los intermetálicos mostraron agrietamiento y desprendimiento de la costra de óxido. La composición química de los intermetálicos tuvo un papel importante en la definición de la morfología del óxido formado y el grado de daño.

  9. The intermetallic bonding between a ring carrier and aluminum piston alloy

    Directory of Open Access Journals (Sweden)

    Manasijevic, Srećko

    2015-09-01

    Full Text Available This paper presents the results of investigating the formation of intermetallic bond between a ring carrier and aluminum piston alloy. The ring carrier is made of austenitic cast iron (Ni-Resist in order to increase the wear resistance of the first ring groove and applied in highly loaded diesel engines. Metallographic examination of the quality of alfin bond was done. A metallographic investigation using an optical microscope in combination with the SEM/EDS analysis of the quality of the intermetallic bonding layer was done. The test results show that can be made successfully as well as the formation of metal connection (alfin bond between the ring carrier and aluminum piston alloy.El artículo presenta los resultados de la investigación sobre la formación de una unión intermetálica entre el portasegmento y la aleación de aluminio del pistón. El portasegmento es una fundición de hierro austenítico (Ni-Resist con el fin de aumentar la resistencia al desgaste de la unión Al-fin del primer segmento y se utiliza en motores diésel altamente cargados. Se realizó un examen metalográfico de la unión intermetálica, mediante un microscopio óptico en combinación con SEM/EDS. Los satisfactorios resultados obtenidos muestran la formación de contacto metálico (unión Al-fin del primer segmento entre el portasegmento y la aleación de aluminio del pistón.

  10. Reacciones en estado sólido para el sistema Al-MoO3 en la fabricación de materiales compuestos Al2O3-aluminuros de Mo

    Directory of Open Access Journals (Sweden)

    Marín, J.

    2002-02-01

    Full Text Available Ceramic matrix composites reinforced with metallic particles exhibit good mechanical properties. One research line has involved the fabrication of 3A (alumina-aluminide alloys composites via in situ consolidation of aluminum reactive powders mixed with a metallic oxide. In this paper the solid state reactions for the Al-MoO3 system and the effect of the precursor compositions for obtaining Al2O3 composites and intermetallic aluminides are studied. The reactions in vacuum for the 25 °C to 750 °C temperature range, and the microstructural evolution up to 1200 °C were studied. DTA-TG and DSC were used to determine that a heating rate of 1 °C/min at the critical range of 500-600 °C, resulted in controlled aluminothermic reactions. XRD and SEM showed that in the sintered composites a microstructure composed of an Al2O3 matrix and a Mo aluminide /metallic Mo dispersed phase was present. The precursor composition affects the dispersed phase in the composite (Mo aluminides and/or metallic Mo, the relative Al2O3 /second phase quantities, and the hardness of the composite sintered at 1450 °C.

    Los materiales compuestos de matriz cerámica (CMC's de Al2O3 reforzados con partículas metálicas tienen propiedades mecánicas muy atractivas. Un área de investigación emergente es la fabricación de compuestos 3A (Alumina-Aluminide-Alloys, mediante la formación in situ de Al2O3 reforzada con metal elemental y/o aluminuros del metal, partiendo de polvos de aluminio y de óxidos metálicos. En este trabajo se estudian las reacciones en estado sólido para el sistema Al-MoO3. Las reacciones de aluminotermia se estudian en vacío para el rango de temperaturas entre 25 °C y 750 °C y su evolución microestructural hasta 1.200 °C. Mediante análisis calorimétrico (DTA-TG y DSC se determinó que para una

  11. Strength and thermal stability of Cu-Al2O3 composite obtained by internal oxidation

    Directory of Open Access Journals (Sweden)

    Jovanovic, M. T.

    2010-12-01

    Full Text Available The objective of the work is to study the effects of the high-energy milling on strengthening, thermal stability and electrical conductivity of Cu-Al2O3 composite. The prealloyed copper powders, atomized in inert gas and containing 3 wt. % Al, were milled up to 20 h in the planetary ball mill to oxidize in situ aluminium with oxygen from the air. Composite compacts were obtained by hot-pressing in an argon atmosphere at 800 °C for 3 h under the pressure of 35MPa. The microstructural characterization was performed by the optical microscope, scanning electron microscope (SEM, transmission electron microscope (TEM and X-ray diffraction analysis (XRD. The microhardness, electrical conductivity and density measurements were also carried out. The effect of internal oxidation and high-energy milling on strengthening of Cu-Al2O3 composite was significant, The increase of the microhardness of composite compacts (292 HV is almost threefold comparing to compacts processed from the as-received Cu-3 wt. % Al powder (102 HV. The grain size of Cu-Al2O3 compacts processed from 5 and 20 h-milled powders was 75 and 45 nm, respectively. The small increase in the grain size and the small microhardness drop indicate the high thermal stability of Cu-Al2O3 composite during high-temperature exposure at 800 °C.El objetivo del trabajo es el estudio de los efectos de la pulverización con altas energías sobre la resistencia, estabilidad térmica y conductividad eléctrica del compuesto Cu-Al2O3. El polvo pre-aleado de cobre, obtenido a través de la atomización con gas inerte y con un contenido de 3wt. % Al, se molió durante 20 h en el molino planetario de bolas dando lugar a la oxidación in situ del aluminio con el oxígeno del aire. El compuesto compactado se ha obtenido mediante prensado en caliente en atmósfera de argón a 800 °C durante 3 h y a una presión de 35MPa. La caracterización microestructural se hizo a través de microscopia óptica, microscopia

  12. P-type poly-Si prepared by low-temperature aluminum-induced crystallization and doping for solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, Yasuhiro; Yu, Zhenrui; Morales-Acevedo, Arturo [CINVESTAV-IPN, Mexico, D.F. (Mexico)

    2000-07-01

    P-type poly-Si thin films prepared by low temperature aluminum-induced crystallization and doping are reported. The starting material was boron-doped a-Si:H prepared by PECVD on glass substrates. Aluminum layers with different thickness were evaporated on a-Si:H surface and conventional thermal annealing was performed at temperatures ranging from 300 to 550 Celsius degrees. XRD, SIMS, and Hall effect measurements were carried out to characterize the annealed Al could be crystallized at temperature as low as 300 Celsius degrees in 60 minutes. This material has high carrier concentration as well as high Hall mobility and can be used as a p-layer of seed layer for thin film poly-Si solar cells. The technique reported here is compatible with PECVD process. [Spanish] Se informa sobre la preparacion de peliculas delgadas tipo P y Poli-Si mediante la cristalizacion inducida de aluminio a baja temperatura y el dopado. El material inicial era de boro dopado y a-Si:H preparado PECVD sobre substratos de vidrio. Se evaporaron capas de aluminio de diferente espesor sobre una superficie de a-Si:H y se llevo a cabo un destemplado termico convencional a temperaturas que varian entre 300 y 500 grados Celsius. Se llevaron a cabo mediciones de XRB, SIMS y del efecto Hall para caracterizar el aluminio destemplado para que pudiera ser cristalizado a temperaturas tan bajas como 300 grados Celsius en 60 minutos. Este material tiene una alta concentracion portadora asi como una alta movilidad Hall y puede usarse como una capa de semilla para celdas solares de pelicula delgada Poli-Si. La tecnica reportada aqui es compatible con el proceso PECVD.

  13. Modelación matemática del mezclado en ollas (cucharas de aluminio equipadas con la técnica de desgasificación rotor-inyector

    Directory of Open Access Journals (Sweden)

    Ramírez-Argáez, M. A.

    2006-06-01

    Full Text Available In this work a fundamental Eulerian mathematical model was developed to study fluid flow and mixing phenomena in aluminum ladles equipped with impeller for deshidrogenization treatment. The effect of critical process parameters such as rotor speed, depth of immersion, gas flow rate, and type of rotor on the mixing behavior and vortex formation was analyzed with this model. The model simulates operation with and without gas injection and it was developed on the commercial CFD code PHOENICS 3.4 in order to solve all conservation equations governing the process, i.e. continuity, 3D turbulent Navier-Stokes and the k-e turbulence model for a two-phase fluid flow problem using the Inter Phase Slip Algorithm (IPSA. In order to realistically represent the process, shape of the furnace and three kinds of impellers were drawn by employing Body Fitted Coordinates (BFC. From the results it was concluded that mixing behavior is highly dependent on the rotor speed and on the rotor type. Mixing time is improved when: 1 Impeller is located at a depth of 0.229m into the aluminum bath, 2 By using high rotor speeds, 3 By using ladles with a high aspect ratio of Diameter to Height, and 4By using an impeller with notches.

    Se desarrolló un modelo matemático Euleriano para analizar el flujo de fluidos y el mezclado en ollas (cucharas de tratamiento de aluminio equipadas con rotor-inyector, variando parámetros del proceso como la velocidad de giro del rotor, la distancia de inmersión de la flecha, el flujo de gas, el tipo de rotor y el factor de forma de la olla (cuchara (relación altura/diámetro. El modelo matemático simula la operación, con y sin inyección de gas, a través del rotor, empleando el código comercial PHOENICS donde se resolvieron las ecuaciones de continuidad, momento, especies químicas y turbulencia, k-e, de forma simultánea, tanto para la fase líquida como para la gaseosa. El dominio se dibujó, realistamente, empleando coordenadas

  14. Evaluation of the effect of Ni-P coating on the corrosion resistance of the aluminium 7075 T6 alloy

    Directory of Open Access Journals (Sweden)

    Gil, L.

    2008-02-01

    Full Text Available The aluminum alloy 7075-T6 is a structural alloy widely used for aeronautical applications due to its high relationship between mechanical resistance and weight. Depending upon the environmental conditions, many types of corrosion mechanisms such as intergranular, exfoliation, have been found to occur in aircraft structural aluminum alloys. A significant advance in order to improve the behavior of this alloy is related to the application of the autocatalytic Ni-P coating which confers an excellent corrosion resistance coupled with both reduced erosive wear and higher hardness. The purpose of this work was to investigate the effect of the application of a Ni-P coating on the corrosion resistance of an aluminum 7075-T6 alloy. The results obtained indicated that the application of the Ni-P coatings diminishes the susceptibility to pitting and makes the aluminum 7075 T6 alloy immune to the exfoliation corrosion attack.

    La aleación de aluminio 7075-T6 es una aleación estructural ampliamente utilizada para aplicaciones aeronáuticas, debido a su alta relación entre resistencia mecánica y peso. Dependiendo de las condiciones ambientales, algunos mecanismos de corrosion tales como intergranular, exfoliacion, picadura y crevice se ha encontrado que ocurren en estructuras de aviones de aleaciones de aluminio. Un avance siginificativo para mejorar el comportamiento de esta aleación es la aplicación de recubrimientos autocatalíticos de Ni-P, los cuales confieren una excelente resistencia a la corrosión acoplado con una reducción del desgaste erosivo y un aumento de la dureza. El propósito de este trabajo fue investigar el efecto de la aplicación de un recubrimiento de Ni-P sobre la resistencia a la corrosión de una aleación de aluminio 7075-T6. Los resultados obtenidos indican que la aplicación del recubrimiento de Ni-P disminuye la susceptibilidad a la picadura y hace a la aleación de aluminio 7075 T6, prácticamente inmune al ataque

  15. Aplicación de materiales orgánicos e inorgánicos en la adsorción de fósforo en un Oxisol

    OpenAIRE

    Daza-Torres,Martha C.; Álvarez-Herrera,Javier G.; Camacho-Tamayo,Jesús H.

    2008-01-01

    Los oxisoles presentan alta fijación de fósforo (P) ocasionada por hidróxidos y óxidos de hierro y aluminio presentes en las arcillas. La aplicación de mezclas de materiales orgánicos e inorgánicos puede ayudar a disminuir dicha fijación. Se utilizaron dos materiales orgánicos (gallinaza y compost) y dos materiales inorgánicos (Cal y Superfosfato triple). Se establecieron un total de trece tratamientos dispuestos en bloques al azar y compuestos por diferentes combinaciones entre fertilizantes...

  16. Análisis de ciclo de vida para la selección de electrodos en la electrocoagulación de aguas residuales de la industria papelera

    OpenAIRE

    López Grimau, Víctor; Amante García, Beatriz; Canals Casals, Lluc

    2017-01-01

    La electrocoagulación es una técnica electroquímica de tratamiento de aguas residuales basada en la generación in situ del coagulante. Se utilizan ánodos sacrificables de Hierro o de Aluminio dando lugar a cationes Fe3+ o Al3+ que actúan como coagulantes de los compuestos orgánicos presentes en el agua residual. La electrocoagulación presenta importantes ventajas en frente de la coagulación convencional con adición de sales, tales como su mejor control de la dosificación, no re...

  17. VladBot. Robot para posicionamiento de medida

    OpenAIRE

    Plata Rueda, Ángel

    2013-01-01

    VladBot es un robot autónomo diseñado para posicionar en interiores un micrófono de medida. Este prototipo puede valorar la idea de automatizar medidas acústicas en interiores mediante un robot autónomo. Posee dos ruedas motrices y una rueda loca. Ésta rueda loca aporta maniobrabilidad al robot. Un soporte extensible hecho de aluminio sostiene el micrófono de medida. VladBot ha sido diseñado con tecnologías de bajo coste y bajo una plataforma abierta, Arduino. Arduino es una plataforma el...

  18. Estudio de las propiedades mecánicas en materiales compuestos de matriz aluminio pulvimetalúrgicos conformados mediante forja o extrusión

    Directory of Open Access Journals (Sweden)

    Busquets, D.

    2005-10-01

    Full Text Available We have developed composite materials from AA6061 aluminium alloy powders used as matrix and ceramics powders of boron carbide, silicon carbide and boron nitride, used as reinforcements in 2.5, 5.0, 1.5 and 10 % vol. by mechanical mixing and milling in planetary mill at 360 rpm vial velocity for 4 h followed of hot stamping and extrusion process on green compacts. Mechanical properties obtained from tensile tests are influenced by the heat treatment, reinforcement fractions and nature. Moreover, these mechanical characteristics are dependent from the processing route. Optical and Scanning Electron Microscopy analysis revealed the microstructure of materials and let describe the tripartite relation; structure-processing-properties, of the developed materials.

    Partiendo de polvos de aleación de aluminio AA6061 empleada como matriz y de polvos cerámicos de carburo de boro, carburo de silicio y nitruro de boro, utilizados como refuerzo en fracciones volumétricas de 2,5, 5,0, 7,5 y 10 %, se ban desarrollado materiales compuestos, mediante la mezcla y molienda mecánica de estos polvos, en molino planetario a 360 rpm durante 4 h y posterior estampación y extrusión en caliente de compactos en verde. Las propiedades mecánicas se determinaron mediante ensayos de tracción, observándose gran influencia del tratamiento térmico, contenido y naturaleza del refuerzo, sobre estas propiedades. Por otro lado, se encontró que estas características son igualmente dependientes de la ruta de producción de estos materiales. Los análisis llevados a cabo mediante microscopía óptica y microscopía electrónica de barrido, permitieron describir la relación tripartita, estructura-procesamiento-propiedades, de los materiales aquí desarrollados.

  19. Estudio de la intercara de uniones entre metales disímiles por medio de ultrasonido

    Directory of Open Access Journals (Sweden)

    López, G. A.

    1999-02-01

    Full Text Available As a result of the associated problems to evaluate bonding characteristics of interfaces between dissimilar metals, mainly those cladded, it has been propposed the use of ultrasonic methods. Acoustic impedance methods had been tested succesfully in the study of plastic-aluminium (glued and babbit-steel (bearing interfaces. Preliminary results on explosively bonded aluminium-steel and aluminium-lead interfaces are presented. A digital ultrasonic device with a 5 Mhz transducer was used in this study. So far, results have shown that "VID" signal gives an acceptance criterion based on the ratio of amplitudes coming from interface and bottom surface, meanwhile "RF" signal gives the same criterion based on wave form. It is concluded that VID and RF signals could be used to achieve characteristics of the bonded interfaces.

    Como resultado de las dificultades encontradas para determinar las características de la intercara entre uniones de materiales disímiles, sobre todo aquellas empleadas en los recubrimientos, surge la posibilidad de emplear las técnicas de ultrasonido. Las técnicas basadas en la diferencia de impedancia acústica se han usado de manera exitosa para caracterizar las intercaras plástico-aluminio (adheridas y metal babbit-acero (en cojinetes. En este estudio se analizan, de manera preliminar, las intercaras de pares aluminio-acero y aluminio-plomo obtenidos por medio de soldadura por explosivos. Se utilizó un sistema de adquisición de señales digitales ultrasónicas y un transductor de 5 MHz. Los resultados obtenidos hasta el momento indican que la representación de la señal en forma de "VID" proporciona un criterio de aceptación basado en la relación entre las amplitudes de la intercara y la superficie posterior, mientras que la señal de "RF" proporciona un criterio de aceptación basado en la forma de la onda. Se concluye que es posible emplear las señales VID y RF para establecer criterios de aceptación de la uni

  20. Aluminum coating by fluidized bed chemical vapor deposition on austenitic stainless steels AISI 304 and AISI 316

    Directory of Open Access Journals (Sweden)

    Jose Luddey Marulanda-Arevalo

    2015-01-01

    Full Text Available Los revestimientos de aluminio f ueron depositados sobre aceros inoxidables AISI 304 y AISI 316 en el rango de temperatura de 5 60 a 600 °C por deposición química de vapor en lecho fluidizado(CVD – FBR. Se utilizó un lecho que consistía en 10 % de aluminio en polvo y 90 % de lecho inerte (alúmina, el cual fue fluidizado con Ar y como ga ses activadores se utilizó una mezcla de ácido clorhídrico con hidrógeno (HCl/H 2 . En el recubrimiento si n tratamiento térmico están las siguiente s especies: Al 13 Fe 4 , Fe 2 Al 5 , FeAl 2 y Al 5 FeNi, las cuales están presentes para ambos aceros. Además, el tratamiento térmico provoca la difusa de alu minio hacia el sustrato y la difusa de hierro del sustrato haci a la superficie del recubrimiento, haciendo la trans formación de los compuestos ant eriores a FeAl, Fe 2 Al 5 , FeAl 2 , Al 0.99 Fe 0.99 Ni 0.02 , AlNi y el Fe 2 AlCr. Se realizó la simulación termodinámica con el s oftware Thermo Calc para obt ener información de la posible composición y la cantidad de mat erial depositado, para condiciones seleccionadas. Las muestras recubi ertas y sin recubrir, se expus ieron a 750 ºC en una atmósfera d onde el vapor agua se transporta a las muestras usando un flujo de N 2 de 40 ml/min, más 100 % vapor de agua (H 2 O. Los dos sustratos sin revestir se comportaron de manera diferente, ya que el acero AISI 304 soportó bien el a taque y ganó poco peso (0.49 mg/cm 2 , en comparación con el acero AISI 316 que perdió mucho peso (25.4 mg/cm 2 . Los aceros recubiertos ganaron poco de peso durante las mil horas de exposición (0.26 mg/cm 2 y soportaron muy bien el ataque corrosivo en c omparación con sustratos sin r ecubrimiento.

  1. Protección contra la corrosión de aleaciones de aluminio mediante recubrimientos sol-gel

    Directory of Open Access Journals (Sweden)

    Conde, A.

    2002-06-01

    Full Text Available Present paper studies the corrosion protection of three new nanomeric coatings obtained from modified silanes and cured at low temperatures. The synthesis of these coatings is carried out starting from a mixture of two sols separately prepared: a prehydrolized GPTS (glicidoxipropiltrimetoxisilano and a second sol TEOS/MTES. Adding to this initial sol a colloidal solution of 25% in weight of commercial particles of SiO2, Aerosil 300 and Aerosil R972 respectively can be obtained thicker nanomeric coatings. Once synthesized, they were deposited by means of the spin coating method onto two aluminum alloys, 5555 and 3005 used as substrates. The final thickness of the coatings is about 10 μm, for the coating without particles and slightly higher, 12-14 μm approximately, for the coatings with particles. The electrochemical results indicated that, in all cases, the coated samples presented an improvement in the corrosion behavior in comparison with bare alloys in aggressive media of NaCl. The corrosion rate decreased three orders of magnitude for the coatings with particles and lower for those that do not contain particles.

    En el presente trabajo se estudia la protección frente a la corrosión que proporcionan tres nuevos recubrimientos nanoméricos de baja temperatura de curado obtenidos a partir de silanos modificados. La síntesis de estos recubrimientos se realiza a partir de una mezcla de dos soles, GPTS (glicidoxipropiltrimetoxisilano prehidrolizado y un segundo sol TEOS/MTES. Añadiendo a este sol inicial una disolución coloidal de partículas se obtienen recubrimientos nanoméricos de mayor espesor. En el presente trabajo los recubrimientos particulados se obtuvieron incorporando un 25% en peso de partículas comerciales de SiO2, Aerosil 300 y Aerosil R972 respectivamente. Una vez sintetizados, se depositaron mediante el método de centrifugado, sobre dos aleaciones de aluminio, 5555 y 3005 empleadas como substratos. El espesor final

  2. Evolución Microestructural en Uniones de la Aleación Ti-6Al-4V Mediante el Proceso de Soldadura de Punto por Fricción-agitación

    Directory of Open Access Journals (Sweden)

    Flor Araceli Garcia-Castillo

    Full Text Available Resumen La soldadura de punto por fricción-agitación (Friction Stir Spot Welding, FSSW es un tema de reciente desarrollo e interés, principalmente en aleaciones de Titanio, ya que existen estudios previos realizados en aleaciones de aluminio, magnesio, aceros y polímeros. Las aleaciones de Titanio tienen una amplia aplicación en la industria aeronáutica, principalmente como componentes en el tren de aterrizaje en aviones comerciales, por lo cual este trabajo se centra en la aleación Ti-6Al-4V, este tipo de aleación presenta fases alfa (α y beta (β, brindado mejor balance en propiedades mecánicas de dureza y esfuerzo a la tensión. El proceso FSSW se realizó mediante un centro de maquinado de alta velocidad, utilizando una velocidad de rotación de 500 RPM, una velocidad de penetración de la herramienta de 2 mm/s y 3 s en tiempo de sostenimiento, en láminas con un espesor de 1,5 mm y una longitud de traslape de 20 mm. Los resultados mostraron el efecto de las variables del proceso de soldadura FSSW sobre la microestructura de la aleación Ti-6Al-4V ocasionada por el efecto térmico y la deformación plástica del proceso de la soldadura, concluyendo que una adecuada combinación de parámetros permite realizar una unión sin defectos.

  3. Estudio calorimétrico no isotérmico del proceso de precipitación en una aleación de Cu-10 % Ni-3 % Al

    Directory of Open Access Journals (Sweden)

    Donoso, E.

    2007-04-01

    Full Text Available Using differential scanning calorimetry (DSC, the precipitation process of nickel and aluminium atoms from a solid solution of Cu-Ni-Al were studied. Analysis of calorimetric traces displayed shows the presence of two exothermic reactions (stage 1 and 2, which were interpreted as the formation of two types of precipitates. The first stage corresponds to the formation of an equilibrium b (NiAl phase, whilst stage 2 corresponds to the formation of g’ precipitate with Ni3Al stoichiometric composition. It is observed the shift of the traces to lower temperatures while linear heating rate decrease. The activation reaction energies were evaluated from modified Kissinger’s method. Kinetic parameters were calculated by means Johnson-Mehl-Avrami formalism. The values obtained for parameter n were indicative of a particle nucleation process from pre-existent nucleus. Microhardness measurements and micrographies obtained by transmission electron microscopy were helpful to confirm the formation and the dissolution of the mentioned phases.

    Mediante calorimetría diferencial de barrido (DSC, se estudió el proceso de precipitación de átomos de níquel y aluminio a partir de una solución sólida de Cu-Ni-Al. El análisis de las curvas calorimétricas muestra la presencia de dos reacciones exotérmicas (etapas 1 y 2, que se interpretan como la formación de dos tipos de precipitados. La primera etapa corresponde a la formación de la fase de equilibrio b (NiAl, en tanto que la etapa 2 corresponde a la formación del precipitado g’ de composición estequiométrica Ni3Al. Además, se observa que las curvas se desplazan a temperaturas más bajas a medida que la velocidad de calentamiento lineal decrece. Las energías de activación de las reacciones fueron evaluadas a partir de un método de Kissinger modificado. Los parámetros cinéticos se calcularon mediante el formalismo de Johnson- Mehl-Avrami. Los valores de n obtenidos

  4. Estrategias de enraizamiento de genotipos Brachiaria en suelos ácidos y de baja fertilidad en Colombia Rooting strategies of Brachiaria genotypes in acid and low fertility soils of Colombia

    Directory of Open Access Journals (Sweden)

    Jaumer Ricaurte

    Full Text Available En un Haplustox de los Llanos Orientales de Colombia se evaluaron durante 41 meses 6 genotipos de Brachiaria con resistencia variable a niveles altos de Al+3 en dos niveles de nutrientes. Los genotipos con resistencia media y alta mantuvieron altas producciones de biomasa aérea en los primeros meses, decrecieron a valores medios y estables hacia los 21 meses. La producción de biomasa y longitud de raíces en los genotipos de Brachiaria y especies de sabana nativa fue mayor en época lluviosa, con alta producción en los primeros 5 cm del perfil de suelo. Las gramíneas de la sabana nativa y B. decumbens CIAT 606 (altamente resistente a Al+3 generaron raíces finas y menor biomasa de raíces. Durante la época seca los genotipos de Brachiaria con resistencia media y alta a aluminio generaron raíces más profundas que la sabana nativa. La época seca indujo una producción de longitud y biomasa de raíces proporcionalmente más profundas que la lluviosa, tanto en genotipos de Brachiaria con resistencia media y alta a aluminio como en especies de la sabana nativa.In a Typic Haplustox soil in the “Altillanura” of the Eastern Plains (Llanos Orientales of Colombia Shoot biomass production was evaluated, during 41 months in 6 Brachiaria genotypes with variable resistance to high Al levels. with two nutrient levels. Moderate and highly Al-resistant Brachiaria genotypes maintained high shoot biomass production in early months of establishment, declined to medium values until 21 months. Root biomass and root length production of Brachiaria genotypes, as well as native savanna grasses, was greater during rainy season, with a high root production in the first 5 cm of the soil. Savanna species and the genotypes B. decumbens CIAT 606 (high Al+3 resistant produced finer roots and less root biomass than native savanna species. The dry season induced a proportional increase in deeper root length and biomass production compared with rainy season in both

  5. Rheological characterization of LDPE{sub Al} (low density polyethylene and aluminum) e HDPE (high density polyethylene); Caracterizacao das propriedades reologicas da mistura LDPE{sub Al} (polietileno de baixa densidade e aluminio) e HDPE (polietileno de alta densidade)

    Energy Technology Data Exchange (ETDEWEB)

    Santa Marinha, Ana Beatriz Abreu; Pacheco, Elen Beatriz Acordi Vasques; Monteiro, Elisabeth Ermel da Costa [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Macromoleculas

    2008-07-01

    The long life packaging contains paper, polyethylene and aluminum for packaging of food. A few part of total amount produced is recycled and another is discharged in landfills in Brazil. The low density polyethylene and aluminum (LDPE{sub Al}) was obtained from recycling this packaging. The rheological properties of the blends were intermediate to ones of the pure polymers. In a general way, the rheological properties were not modified by the aluminum presence. (author)

  6. Modelización del perfil de soldadura y de la cavidad de vapor en la aleación de aluminio 5182 soldada con láser

    Directory of Open Access Journals (Sweden)

    Pastor, M.

    2001-12-01

    Full Text Available The purpose of this research is the study of the laser welding process of the aluminum alloy 5182 and the development of models by means of the COSMOS/M package, in order to predict the shape of the keyhole and the temperatures profile of the weld. Modeling has been done considering the degree of defocusing. The heat flow applied on the models was a Gauss flow, considering the condition of the focused face and the conditions of negative and positive defocusing. The validity of the models has been demonstrated comparing their results with those obtained by experimental tests. The extent of defocusing of laser beam affected the stability of the keyhole and welding geometry.

    El presente trabajo se introduce en el desarrollo de modelos para predecir la forma de la cavidad de vapor y el perfil de la aleación de aluminio 5182 con soldadura láser. Para el procesamiento del modelo se ha empleado el paquete profesional de Elementos Finitos COSMOS/M. La modelización de la soldadura se realizó considerando como variable el grado de desenfoque del haz de láser y la distribución del flujo de calor según un modelo Gaussiano, para las condiciones de haz enfocado y de desenfoque negativo y positivo. La validez de los resultados obtenidos se comprobó mediante la comparación con los resultados obtenidos en pruebas experimentales, concluyéndose que el grado de desenfoque del haz del láser afecta notablemente la estabilidad de la cavidad de vapor y la geometría de la soldadura.

  7. Evaluación de la toxicidad por dosis única y tolerancia local de la vacuna vax-SPIRAL® en ratas Sprague Dawley

    Directory of Open Access Journals (Sweden)

    Juan F. Infante

    2004-04-01

    Full Text Available Las pruebas preclínicas de toxicidad en dosis única y en dosis repetidas brindan una valiosa información sobre la seguridad del producto, al incluir el estudio macroscópico e histopatológico de órganos importantes, así como evaluaciones de las vías de administración y el régimen de dosificación. Cuba desarrolló una vacuna polivalente de células inactivadas químicamente adyuvadas con hidróxido de aluminio, vax-SPIRAL®. Esta vacuna presenta ventajas en relación con otras vacunas como la procedente de la antigua URSS. El esquema de vacunación para humanos consiste en dos dosis de 0,5 mL, separadas por un intervalo óptimo de seis semanas. El objetivo de este estudio de toxicidad en ratas Sprague Dawley fue determinar la toxicidad potencial, letalidad, órganos y sistemas susceptibles y otros eventos adversos, así como la toxicidad en el sitio de inoculación después de la administración de una dosis de la vacuna en estudio. Los resultados indicaron que, bajo las condiciones en estudio y según los criterios establecidos para evaluar los datos obtenidos, la vacuna antileptospirósica trivalente no produce efectos tóxicos en el modelo animal usado. Las únicas alteraciones encontradas fueron formaciones granulomatosas a nivel del sitio de inoculación. Estas formaciones han sido reportadas como pertenecientes al adyuvante de depósito (hidróxido de aluminio, también usado en otras vacunas de aplicación parenteral.

  8. Recuperación de metales del licor de desecho WL en forma de compuestos químicos

    Directory of Open Access Journals (Sweden)

    Pedro R. Bassas

    2001-03-01

    Full Text Available El licor de desecho de la empresa niquelera Pedro Soto Alba-Moa Nickel S.A., conocido como WL, es un licor de gran acidez; contiene elementos pesados junto a otros metales que no son asimilados por el proceso metalúrgico y quedan en el licor, que al verterse, impacta en forma negativa el medio ambiente. Mediante precipitación selectiva en tres etapas, se logra recuperar aluminio y manganeso en forma de sales dobles; níquel, cobalto, cobre y zinc en forma de sulfuros y un licor concentrado de cromo. Se empleó el sulfuro de sodio, el hidróxido de amonio y el hidrógenosulfuro de amonio como agentes precipitantes. El licor residual resultante de este tratamiento pierde su acidez y tiene un bajo contenido de elementos pesados que lo hacen menos agresivo al medio.

  9. Inhibition of the formation of intermetallic compounds in aluminum-steel welded joints by friction stir welding

    Directory of Open Access Journals (Sweden)

    Torres López, Edwar A.

    2015-12-01

    Full Text Available Formation of deleterious phases during welding of aluminum and steel is a challenge of the welding processes, for decades. Friction Stir Welding (FSW has been used in an attempt to reduce formation of intermetallic compounds trough reducing the heat input. In this research, dissimilar joint of 6063-T5 aluminum alloy and AISI-SAE 1020 steel were welded using this technique. The temperature of welded joints was measured during the process. The interface of the welded joints was characterized using optical microscopy, scanning and transmission electron microscopy. Additionally, composition measurements were carried out by X-EDS and DRX. The experimental results revealed that the maximum temperature on the joint studied is less than 360 °C. The microstructural characterization in the aluminum-steel interface showed the absence of intermetallic compounds, which is a condition attributed to the use of welding with low thermal input parameters.La unión de juntas aluminio-acero, sin la formación de fases deletéreas del tipo FexAly, ha sido, por décadas, un desafío para los procesos de soldadura. La soldadura por fricción-agitación ha sido empleada para intentar reducir el aporte térmico y evitar la formación de compuestos intermetálicos. Usando esta técnica fueron soldadas juntas disimilares de aluminio 6063-T5 y acero AISI-SAE 1020. La soldadura fue acompañada de medidas de temperatura durante su ejecución. La interfase de las juntas soldadas fue caracterizada utilizando microscopía óptica, electrónica de barrido y electrónica de transmisión. Adicionalmente fueron realizadas medidas puntuales X-EDS y DRX. Los resultados experimentales revelan que la temperatura máxima en la junta es inferior a 360 °C. La caracterización microestructural en la interfase aluminio-acero demostró la ausencia de compuestos intermetálicos, condición atribuida al uso de parámetros de soldadura con bajo aporte térmico.

  10. Alteraciones auditivas en trabajadores expuestos al ruido industrial

    Directory of Open Access Journals (Sweden)

    Adel Hernández Díaz

    2007-09-01

    Full Text Available Motivados por la importancia del ruido como riesgo laboral en las actividades productivas de la Carpintería de Aluminio "Tomás Alvarez Breto" decidimos realizar un control audiométrico periódico de estos trabajadores con la finalidad de determinar el grado de exposición de los mismos y establecer las recomendaciones más importantes para su protección. Nos propusimos como objetivo determinar el grado de afectación auditiva por ruido en los trabajadores expuestos al riesgo, para lo cual se cuantificaron los niveles de ruido existentes en los diferentes puestos de trabajo, se confeccionaron las historias clínicas y se realizó un examen otoscópico y una prueba audiométrica en ambos oídos para definir el daño acústico y la presencia de hipoacusia profesional en los obreros estudiados. Al concluir el estudio pudimos comprobar que el ruido constituía un contaminante de gran importancia en esta industria. Este riesgo laboral se encontraba por encima del nivel de seguridad de 85 db(A en 9 de los 13 departamentos con que cuenta el centro y ha afectado la salud de los trabajadores ya que existían 77 casos (78,5% de hipoacusia atribuible al ruido y un gran número de trabajadores (30,6% expuestos a elevados niveles de ruido innecesariamente por la naturaleza de su labor. Por todo esto recomendamos tomar medidas que reduzcan el nivel de ruido en los puestos de trabajo donde existían niveles superiores a los permitidos, exigirse el uso de los medios de protección auditiva en los trabajadores expuestos y cumplirse estrictamente con los exámenes médicos preventivos, incluyendo las pruebas audiométricas anualmente.Motivated by the importance of the noise like labour risk in the productive activities of Aluminium Carpentry Tomas Alvarez Breto we decide to carry out a control periodic audiometric of these workers with the purpose of to determine the degree of exhibition of the same ones and to establish the most important recommendations for

  11. Al-Qurû’ fi Al-Qur’an ‘Inda Al-Anbary fi Al-Adhdâd

    Directory of Open Access Journals (Sweden)

    Raushani Azza

    2018-03-01

    Full Text Available This study examines about the term al-Qurû in the Qur’an. Al-Qurû is one of the most popular discussions among muslim scholars and mufasir, both in terms of language and fiqh. However, there is a bate among muslim scholar and mufasir about the meaning of al-Qurû. It’s because al-Qurû is one of the sentence of al-Adhdâd wich has two meaning, especially in the Qur’an, namely haid (menstruation and thahr. One of the most popular muslim scholar who concern in Qur’an and Arabic is al-Anbari with his book al-Adhdâd. Al-Anbari explains that Qurû has two meanings, First, al-Qurû in etymology is the form of Jama’ from aqra and qurû. Second, al-Qurû has a meaning of menstruation, thahr, or the period of iddah as a sign of being allowed to remarry after certain period of time.

  12. Al-Âyah al-Mutasyâbihât al-Lafzhiyyah fi Sûrah al-An’âm ‘Inda al-Kirmâny

    Directory of Open Access Journals (Sweden)

    Hikmatiar Pasya

    2017-07-01

    Full Text Available This paper discusses about the verses of mutasyâbihât in the Quran. The debate of this verses caused various opinions. The meaning of the mutasyâbihât in this paper is the similarity and difference of the words in the Qur'an. Mufasir have different opinion about the meaning of the verse of mutasyâbihât al-lafdzi. In addition, many Hufadz of the Quran who are confused from one verse to another, or one chapter to another. It’s because similarity of verses in the Qur'an with other verses. So the writer wants to explain the verses mutasyâbihât al-lafdzi in the perspective of Hamzh al-Karmani in Surah al-An'âm. In this discussion the author discovers some passages in mutasyâbihât al-lafdzi, namely Asrâru al-balaghah fi mutasyabih al-lafdzi, Asrar al-balaghah fi mutasyabih al-hurf, and murâ'ah al-ikhtilâfmurâd bi al-lafdzi al-mukarrar.

  13. Diffusion-induced quadrupole relaxation of 27Al nuclei in dilute Al-Ti, Al-Cr, Al-Mn, and Al-Cu alloys at high temperatures

    International Nuclear Information System (INIS)

    Bottyan, L.; Beke, D.L.; Tompa, K.

    1983-01-01

    The temperature dependence of the laboratory frame spin-lattice relaxation time of 27 Al nuclei is measured in 5N Al and in dilute Al-Ti, Al-Cr, Al-Mn, and Al-Cu alloys at 5.7 and 9.7 MHz resonance frequencies. The relaxation in pure aluminium is found to be purely due to the conduction electrons. An excess T 1 -relaxation contribution is detected in all Al-3d alloys investigated above 670 K. The excess relaxation rate is proportional to the impurity content and the temperature dependence of the excess contribution is of Arrhenius-type with an activation energy of (1.3 +- 0.3) eV for all of the investigated alloys. The relaxation contribution is found to be quadrupolar in origin and is caused by the relative diffusional jumps of solute atoms and Al atoms relatively far from the impurity. (author)

  14. Interfacial phenomena in the reactions of Al-B, Al-Ti-B, and Al-Zr-B alloys with KF-AlF3 and NaF-AlF3 melts

    International Nuclear Information System (INIS)

    Lee, M.S.; Terry, B.S.; Grieveson, P.

    1993-01-01

    The interfacial phenomena occurring during the contacting of liquid Al-B, Al-Ti-B, and Al-Zr-B melts with KF-AlF 3 liquid fluxes have been investigated by optical examination of quenched metal drops previously immersed in the liquid fluxes. Reactions in the Al-B/KF-AlF 3 system involve the formation of metastable AlB 12 at the metal/flux interface. At high KBF 4 levels in the flux, the AlB 12 is dispersed in the flux and also at low KBF 4 levels in the metal. Reactions in the Al-Ti-B/KF-AlF 3 system involve the formation of TiB 2 , which may be dispersed in either the metal or the flux depending upon the composition of the flux. The results obtained for the Al-Ti-B/NaF-AlF 3 and Al-Zr-B/KF-AlF 3 systems were similar to those observed for the Al-Ti-B/KF-AlF 3 system

  15. Synthesizing (ZrAl3 + AlN)/Mg-Al composites by a 'matrix exchange' method

    Science.gov (United States)

    Gao, Tong; Li, Zengqiang; Hu, Kaiqi; Han, Mengxia; Liu, Xiangfa

    2018-06-01

    A method named 'matrix exchange' to synthesize ZrAl3 and AlN reinforced Mg-Al composite was developed in this paper. By inserting Al-10ZrN master alloy into Mg matrix and reheating the cooled ingot to 550 °C, Al and Mg atoms diffuse to the opposite side. As a result, liquid melt occurs once the interface areas reach to proper compositions. Then dissolved Al atoms react with ZrN, leading to the in-situ formation of ZrAl3 and AlN particles, while the Al matrix is finally replaced by Mg. This study provides a new insight for preparing Mg composites.

  16. Coupled growth of Al-Al2Cu eutectics in Al-Cu-Ag alloys

    International Nuclear Information System (INIS)

    Hecht, U; Witusiewicz, V; Drevermann, A

    2012-01-01

    Coupled eutectic growth of Al and Al 2 Cu was investigated in univariant Al-Cu-Ag alloys during solidification with planar and cellular morphology. Experiments reveal the dynamic selection of small spacings, below the minimum undercooling spacing and show that distinct morphological features pertain to nearly isotropic or anisotropic Al-Al 2 Cu interfaces.

  17. AL ITTIJAHAT AL MUNHARIFAH FI AT TAFSIR LI BADLI ASHAB AL MADZAHIB AL NAHWIYYAH WA BADL MAN YAJHALUNA QAWAID AL LUGHAH AL ARABIYYAH FI NADHAR MUHAMMAD HUSAIN AL DZAHABIY

    Directory of Open Access Journals (Sweden)

    Misbakhudin Misbakhudin

    2017-06-01

    Full Text Available One of the most precious achievement in qur’anic studies was the book of Al-Ittijâhât al-Munharifah fî al-Tafsîr: Dawâfi’uha wa Daf’uha written by A great Islamic scholar, Muhammad Husein al-Dzahabî. He was succeeded in discussing several issues of corruptions of the exegesis of the holy Qur’an. This article is aimed to explain and to describe his analysis toward several corrupted linguist interpretations in their originations and such corrupted linguistic interpretations of the holy Qur’an which are ignoring Arabic structures and grammers

  18. Drainage effect in eutectic Al-Si foam using similar alporas process; Efeito de drenagem em espumas de liga de aluminio silicio eutetico utilizando processo similar ao alporas

    Energy Technology Data Exchange (ETDEWEB)

    Filho, M.O.; Junior, A.C.S; Ferrandini, P.L. [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), SP (Brazil). Departamento de Materiais e Tecnologia; Nakazato, A.Z.; Assis, W.L.S., E-mail: mauriciooliveirafilho@hotmail.com [Universidade Federal Fluminense (UFF), Resende, RJ (Brazil). Escola de Engenharia de Volta Redonda

    2016-07-01

    Cellular materials have particular properties. This properties are very interesting in various type of industries, as construction, automobile and shipbuilding. Two reasons why metal foams are apply in more companies are difficult process control and high production costs. Therefore, this study aims to analyze the drainage effect in four samples produced with alloy Al-Si eutectic using CaCO{sub 3} as foaming agent, since this is low cost than TiH{sub 2} used normally in Alporas process and this foam have well pores uniform. For these samples has been used 700°C during all process, mixing time was 180 seconds, holding time was 150 seconds and 3,5 w.t% CaCO3. Therefore, these samples were cut transversally and analyzed what were the drainage effect on the apparent density, relative density and porosity. The free zone bubbles were noticed in all the samples. (author)

  19. Utilización del mineral de manganeso (pirolusita en la producción de aceros al carbono

    Directory of Open Access Journals (Sweden)

    Aerles Batista-Cabrera

    2003-03-01

    Full Text Available Los métodos tradicionales de producción de acero utilizan el ferromanganeso para obtener el porcentaje de Mn en la marca establecida según la norma cubana, pero este compuesto es altamente costoso. Se ensayó, en la producción del Ac 35, sustituir el ferromanganeso por el mineral pirolusita (MnO2 con el fin de reducir los costos. Se evaluaron dos variantes de sustitución: la primera consiste en añadir el mineral con virutas de aluminio y coque (o residuos de electrodos sobre la escoria del metal durante el proceso de reducción, en tanto que la segunda variante emplea el mineral de manganeso en lugar del de hierro durante el proceso de oxidación de las impurezas. Se encontró que ambas variantes son factibles y que la segunda resulta, además, ser más económica

  20. Familial ALS

    Science.gov (United States)

    Boylan, Kevin

    2015-01-01

    Synopsis Genes linked to ALS susceptibility are being identified at an increasing rate owing to advances in molecular genetic technology. Genetic mechanisms in ALS pathogenesis appear to exert major effects in ~10% of patients, but genetic factors at some level may be important components of disease risk in most ALS patients. Identification of gene variants associated with ALS has informed concepts of the pathogenesis of ALS, aided the identification of therapeutic targets, facilitated research to develop new ALS biomarkers, and supported the establishment of clinical diagnostic tests for ALS-linked genes. Translation of this knowledge to ALS therapy development is ongoing. PMID:26515623

  1. Malamih al-Ashwat al-'Arabiyyah wa Makharijaha

    Directory of Open Access Journals (Sweden)

    Amrah Muhammad Kasim

    2015-12-01

    Full Text Available This writing discusses on al-ashwat al-‘arabiyyah that is known with “phonetic” term. It talks and interprets makharij al-huruf or place for producing sounds and also processing production of sounds by parts of mouth in Arabic language. The problems of sounds and its systems in Arabic language have been conducted by the scholars of al-ashwat al-‘arabiyyah attractively, neatly, and detail and gotten ahead the phonetic western scholars. Part of their analysis results formulate the study about al-ashwat al-sakinah (al-Shamit is known with vocal and consonant sounds in research questions shawait – shawamit. Ibnu Jinni has formulated “harakat”(wowel in Arabic language and dimension of letter  mad and liyn on alif  letter - waw - ya’ (ا و ي, from these letters create  harakat fathah, dammah, and kasrah. Moreover, in this writing also exist the description of hija’i letters and its makhraj that are correct from parts of mouth and the unity of coordinative sounds that produce sounds in morphemes arrangement, in one word that produces meaning. The result of phonological study has divided al-ashwat to be kinds of sound like the pronounced sounds, produced sounds from mouth, and heard sound.

  2. Transient oxidation of Al-deposited Fe-Cr-Al alloy foil

    International Nuclear Information System (INIS)

    Andoh, A.

    1997-01-01

    The oxide phases formed on an Al-deposited Fe-Cr-Al alloy foil and an Fe-Cr-Al alloy foil of the same levels of Al and (La+Ce) contents, and their oxidation kinetics have been studied in air at 1173 and 1373 K using TGA, XRD and SEM. Al deposition promotes the growth of metastable aluminas (θ-Al 2 O 3 , γ-Al 2 O 3 ). Scales consisting of θ-Al 2 O 3 and a small amount of α-Al 2 O 3 develop on the Al-deposited foil at 1173 K and exhibit the whisker-type morphology. In the early stage of oxidation at 1373 K, thick scales consisting of θ-Al 2 O 3 and α-Al 2 O 3 grow rapidly on the Al-deposited foil. The transformation from θ-Al 2 O 3 to α-Al 2 O 3 is very fast, and the scales result in only α-Al 2 O 3 . In contrast, α-Al 2 O 3 scales containing a minor amount of FeAl 2 O 4 develop on the alloy foil. The growth rate of α-Al 2 O 3 scales on the Al-deposited foil is smaller than that on the alloy foil and very close to that on NiAl at 1373 K. (orig.)

  3. Rooting strategies of Brachiaria genotypes in acid and low fertility soils of Colombia Estrategias de enraizamiento de genotipos Brachiaria en suelos ácidos y de baja fertilidad en Colombia

    Directory of Open Access Journals (Sweden)

    Menjivar Juan Carlos

    2007-09-01

    Full Text Available In a Typic Haplustox soil in the “Altillanura” of the Eastern Plains (Llanos Orientales of Colombia Shoot biomass production was evaluated, during 41 months in 6 Brachiaria genotypes with variable resistance to high Al levels. with two nutrient levels. Moderate and highly Al-resistant Brachiaria genotypes maintained high shoot biomass production in early months of establishment, declined to medium values until 21 months. Root biomass and root length production of Brachiaria genotypes, as well as native savanna grasses, was greater during rainy season, with a high root production in the first 5 cm of the soil. Savanna species and the genotypes B. decumbens CIAT 606 (high Al+3 resistant produced finer roots and less root biomass than native savanna species. The dry season induced a proportional increase in deeper root length and biomass production compared with rainy season in both moderately and highly Al-resistant Brachiaria genotypes as well as in native savanna species.En un Haplustox de los Llanos Orientales de Colombia se evaluaron durante 41 meses 6 genotipos de Brachiaria con resistencia variable a niveles altos de Al+3 en dos niveles de nutrientes. Los genotipos con resistencia media y alta mantuvieron altas producciones de biomasa aérea en los primeros meses, decrecieron a valores medios y estables hacia los 21 meses. La producción de biomasa y longitud de raíces en los genotipos de Brachiaria y especies de sabana nativa fue mayor en época lluviosa, con alta producción en los primeros 5 cm del perfil de suelo. Las gramíneas de la sabana nativa y B. decumbens CIAT 606 (altamente resistente a Al+3 generaron raíces finas y menor biomasa de raíces. Durante la época seca los genotipos de

  4. Proton irradiation studies on Al and Al5083 alloy

    Science.gov (United States)

    Bhattacharyya, P.; Gayathri, N.; Bhattacharya, M.; Gupta, A. Dutta; Sarkar, Apu; Dhar, S.; Mitra, M. K.; Mukherjee, P.

    2017-10-01

    The change in the microstructural parameters and microhardness values in 6.5 MeV proton irradiated pure Al and Al5083 alloy samples have been evaluated using different model based techniques of X-ray diffraction Line Profile Analysis (XRD) and microindendation techniques. The detailed line profile analysis of the XRD data showed that the domain size increases and saturates with irradiation dose both in the case of Al and Al5083 alloy. The corresponding microstrain values did not show any change with irradiation dose in the case of the pure Al but showed an increase at higher irradiation doses in the case of Al5083 alloy. The microindendation results showed that unirradiated Al5083 alloy has higher hardness value compared to that of unirradiated pure Al. The hardness increased marginally with irradiation dose in the case of Al5083, whereas for pure Al, there was no significant change with dose.

  5. PEMBARUAN MASLAḤAH DALAM MAQĀṢID AL- SHARĪ‘AH: TELAAH HUMANISTIS TENTANG AL-KULLIYYĀT AL-KHAMSAH

    Directory of Open Access Journals (Sweden)

    Zaenuddin Mansyur

    2012-06-01

    Full Text Available Abstract:   In order to answer a variety of issues faced by human being in the current era, such as human rights abuses, social disintegration, and terrorism, the renewal of Islamic law in the level of theoretical and practical aspects is very urgent. This paper aims to examine one of the Islamic legal reform efforts, namely to build a more technical understanding of the concept of maṣlaḥah contained in the maqāṣīd sharī‘ah, called the al-kulliyat al-khamsah. Therefore, the concept of maṣlaḥah in ḥifẓ al-dīn is technically defined as al-ḥurriyah al-i‘tiqād (freedom of religion and schools; in ḥifẓ al-nafs as al-karamat al-insān (human being breeding; in ḥifẓ al-nasl as ḥifẓ al-usrah (wholeness and harmony of the family; in ḥifẓ al-māl as al-taḍammun al-insān (social solidarity , and in ḥifẓ al-‘aql as al-ḥuqūq as al-tarbiyāt (increasing human resources quality.Abstrak: Demi menjawab aneka persoalan zaman yang dihadapi manusia era sekarang, seperti penyelewengan terhadap HAM, disintegrasi sosial, dan terorisme, maka pembaharuan hukum Islam dalam tataran teoretis dan praktis urgen dilakukan. Tulisan ini bertujuan untuk mengkaji salah satu upaya pembaruan hukum Islam, yaitu membangun pemahaman yang lebih teknis terhadap konsep maṣlaḥah yang terkandung dalam maqāṣīd sharī‘ah, yang disebut dengan al-kulliyāt al-khamsah. Oleh karena itu, konsep maṣlaḥah dalam ḥifẓu al-dīn secara teknis dimaknai sebagai ḥurriyah al-i‘tiqād (kebebasan untuk beragama dan beraliran; dalam ḥifẓu al-nafs sebagai al-karāmāt al-insān (pemuliaan kemanusiaan; dalam ḥifẓu al-nasl sebagai ḥifẓu al-usrah (keutuhan dan keharmonisan keluarga; dalam ḥifẓu al-māl sebagai al-taḍammun al-insān (solidaritas sosial; dan dalam ḥifẓu al-‘aql sebagai al-ḥuqūq al-tarbiyāt (peningkatan sumber daya manusia.

  6. Combustion synthesis of AlB2-Al2O3 composite powders with AlB2 nanowire structures

    Science.gov (United States)

    Yang, Pan; Xiao, Guoqing; Ding, Donghai; Ren, Yun; Yang, Shoulei; Lv, Lihua; Hou, Xing

    2018-05-01

    Using of Al and B2O3 powders as starting materials, and Mg-Al alloy as additives, AlB2-Al2O3 composite powders with AlB2 nanowire structures were successfully fabricated via combustion synthesis method in Ar atmosphere at a pressure of 1.5 MPa. The effect of different amount of Mg-Al alloy on the phase compositions and morphology of the combustion products was investigated. The results revealed that AlB2 and Al2O3 increased, whereas Al decreased with the content of Mg-Al alloy increasing. The impurities MgAl2O4 and AlB12 would exist in the sample with adding of 18 wt% Mg-Al alloy. Interestingly, FESEM/TEM/EDS results showed that AlB2 nanowires were observed in the products when the content of Mg-Al alloy is 6 wt% and 12 wt%. The more AlB2 nanowires can be found as the content of Mg-Al alloy increased. And the yield of AlB2 nanowires with the diameter of about 200 nanometers (nm) and the length up to several tens of micrometers (μm) in the combustion product is highest when the content of Mg-Al alloy is 12 wt%. The vapor, such as Mg-Al (g), B2O2 (g), AlO (g) and Al2O (g), produced during the process of combustion synthesis, reacted with each other to yield AlB2 nanowires by vapor-solid (VS) mechanism and the corresponding model was also proposed.

  7. The effects of boron in TiAl/Ti3Al

    International Nuclear Information System (INIS)

    Feng, C.R.; Michel, D.J.; Crowe, C.R.

    1989-01-01

    The authors discuss the TiAl/Ti 3 Al interfacial misfit dislocations structures investigated by TEM in Ti-45Al alloy and Ti-45Al/TiB 2 composite. For TiAl with c/a = 1.02, only a single set of misfit dislocation arrays are crystallographically possible; these were observed in Ti-45Al alloy. However, the observation of three sets of misfit dislocation arrays in the Ti-45Al/TiB 2 composite suggests that the occupation of octahedral sites in the TiAl structure by excess boron was responsible for a decrease in the c/a ratio leading to an increased fcc character of the TiAl at the TiAl/Ti 3 Al interface

  8. In Situ Fabrication of AlN Coating by Reactive Plasma Spraying of Al/AlN Powder

    Directory of Open Access Journals (Sweden)

    Mohammed Shahien

    2011-10-01

    Full Text Available Reactive plasma spraying is a promising technology for the in situ formation of aluminum nitride (AlN coatings. Recently, it became possible to fabricate cubic-AlN-(c-AlN based coatings through reactive plasma spraying of Al powder in an ambient atmosphere. However, it was difficult to fabricate a coating with high AlN content and suitable thickness due to the coalescence of the Al particles. In this study, the influence of using AlN additive (h-AlN to increase the AlN content of the coating and improve the reaction process was investigated. The simple mixing of Al and AlN powders was not suitable for fabricating AlN coatings through reactive plasma spraying. However, it was possible to prepare a homogenously mixed, agglomerated and dispersed Al/AlN mixture (which enabled in-flight interaction between the powder and the surrounding plasma by wet-mixing in a planetary mill. Increasing the AlN content in the mixture prevented coalescence and increased the nitride content gradually. Using 30 to 40 wt% AlN was sufficient to fabricate a thick (more than 200 µm AlN coating with high hardness (approximately 1000 Hv. The AlN additive prevented the coalescence of Al metal and enhanced post-deposition nitriding through N2 plasma irradiation by allowing the nitriding species in the plasma to impinge on a larger Al surface area. Using AlN as a feedstock additive was found to be a suitable method for fabricating AlN coatings by reactive plasma spraying. Moreover, the fabricated coatings consist of hexagonal (h-AlN, c-AlN (rock-salt and zinc-blend phases and certain oxides: aluminum oxynitride (Al5O6N, cubic sphalerite Al23O27N5 (ALON and Al2O3. The zinc-blend c-AlN and ALON phases were attributed to the transformation of the h-AlN feedstock during the reactive plasma spraying. Thus, the zinc-blend c-Al

  9. Instability of TiC and TiAl3 compounds in Al-10Mg and Al-5Cu alloys by addition of Al-Ti-C master alloy

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The performance of Al-Ti-C master alloy in refining Al-10Mg and A1-5Cu alloys was studied by using electron probe micro-analyzer (EPMA) and X-ray diffractometer (XRD) analysis.The results indicate that there are obvious fading phenomena in both Al-10Mg and Al-5Cu alloys with the addition of Al-5Ti-0.4C refiner which contains TiC and TiAl3 compounds.Mg element has no influence on the stability of TiC and TiAl3, while TiC particles in Al-10Mg alloy react with Al to form Al4C3 particles, resulting in the refinement fading.However, TiC particles are relatively stable in Al-5Cu alloy, while TiAl3 phase reacts with Al2Cu to produce a new phase Ti(Al, Cu)2, which is responsible for the refinement fading in Al-5Cu alloy.These indicate that the refinement fading will not occur only when both the TiC particles and TiAl3 compound of Al-Ti-C refiner are stable in Al alloys.

  10. PEMAHAMAN HADITS TARBAWI BURHAN AL ISLAM AL ZARNUJI DALAM KITAB TA’LIM AL MUTA’ALLIM

    Directory of Open Access Journals (Sweden)

    Benny Afwadzi

    2017-01-01

    Full Text Available This paper explores the understanding of tarbawi (education hadith from one of the major influential clerics in the Islamic educational system, especially in pesantren. He is Burhan al Islam al Zarnuji with his landmark book Ta’lim al Muta’allim. The conclusion that can be drawn is that al Zarnuji has shades of sufistical view in understanding tarbawi hadith. This can be seen in his understanding of hadith on obligation to seek knowledge (thalab al ilmi faridhatun ‘ala kulli muslimin wa muslimatin, which is interpreted as ilm al hal, the science concerning the condition of the human religious or simplistically said as the religious sciences; and the hadith of intention of studying (innama al a’malu bi al niyyat with the intention for the sake of the hereafter and religion, not mundane. Such an understanding is not something taken for granted, but it can be reinterpreted and perfected in accordance with the spirit of the times of context.

  11. Influencia del grado de refuerzo y de la composición de la matriz en la resistencia a la corrosión de materiales compuestos de matriz de aluminio (A3xx.x/SiC en 80% humedad relativa (HR

    Directory of Open Access Journals (Sweden)

    Pardo, A.

    2004-04-01

    Full Text Available A study of the influence of the SiCp proportion of four aluminium metal composites (A380/SiC/10p, A380/SiC/20p, A360/SiC/10p y A360/ SiC/20p on 80%HR at 25 and 50ºC, simulated under climatic chamber. The matrix of A360/SiC/xxp composites is virtually free of Cu while the A380/SiC/xxp matrix contains 1.39-1.44wt%Ni and 3.13-3.45wt%Cu. The kinetics of the corrosion process were studied on the basis of gravimetric tests. The nature of corrosion products was studied as a function of the reinforcement proportion, matrix concentration and test conditions. At the humidity environment tested, both the material corrosion resistance and the stability of the passive layer were high. The damage was low and increased with temperature, SiCp proportion and Cu matrix composition.

    Se estudia la influencia de la proporción de SiC en la resistencia a la corrosión de los materiales compuestos de matriz de aluminio A380/ SiC/10p, A380/SiC/20p, A360/SiC/10p y A360/SiC/20p, cuando operan en un ambiente con 80% HR a 25º y 50ºC, que ha sido simulado mediante cámara climática. La matriz del material A360/SiC/xxp no contiene Cu, mientras que el material A380/SiC/xxp contiene entre el 1,39-1,44% de Ni y 3,13-3,45 de Cu. Se ha llevado a cabo un estudio cinético mediante medidas gravimétricas. Se ha estudiado la naturaleza de los productos de corrosión en función de la proporción de refuerzo, de la composición de la matriz y de las condiciones de exposición al medio agresivo. Para la humedad ensayada, la resistencia a la corrosión de estos materiales es elevada y el grado de protección de la capa pasiva es alto. El grado de daño, aunque es pequeño aumenta con la temperatura y es función tanto de la composición de la matriz como del porcentaje de refuerzo.

  12. Calculation of Gibbs energy of Zr-Al-Ni, Zr-Al-Cu, Al-Ni-Cu and Zr-Al-Ni-Cu liquid alloys based on quasiregular solution model

    International Nuclear Information System (INIS)

    Li, H.Q.; Yang, Y.S.; Tong, W.H.; Wang, Z.Y.

    2007-01-01

    With the effects of electronic structure and atomic size being introduced, the mixing enthalpy as well as the Gibbs energy of the ternary Zr-Al-Cu, Ni-Al-Cu, Zr-Ni-Al and quaternary Zr-Al-Ni-Cu systems are calculated based on quasiregular solution model. The computed results agree well with the experimental data. The sequence of Gibbs energies of different systems is: G Zr-Al-Ni-Cu Zr-Al-Ni Zr-Al-Cu Cu-Al-Ni . To Zr-Al-Cu, Ni-Al-Cu and Zr-Ni-Al, the lowest Gibbs energy locates in the composition range of X Zr 0.39-0.61, X Al = 0.38-0.61; X Ni = 0.39-0.61, X Al = 0.38-0.60 and X Zr = 0.32-0.67, X Al = 0.32-0.66, respectively. And to the Zr-Ni-Al-Cu system with 66.67% Zr, the lowest Gibbs energy is obtained in the region of X Al = 0.63-0.80, X Ni = 0.14-0.24

  13. Bipolar characteristics of AlGaN/AlN/GaN/AlGaN double heterojunction structure with AlGaN as buffer layer

    International Nuclear Information System (INIS)

    Peng, Enchao; Wang, Xiaoliang; Xiao, Hongling; Wang, Cuimei; Yin, Haibo; Chen, Hong; Feng, Chun; Jiang, Lijuan; Hou, Xun; Wang, Zhanguo

    2013-01-01

    Highlights: •2DEG and 2DHG coexist in the AlGaN/AlN/GaN/AlGaN DH-structure. •The sheet densities of 2DEG and 2DHG vary with buffer Al content and GaN thickness. •The conditions for the disappearance of 2DHG are discussed. •Increasing buffer Al content provides better electron confinement. •Dislocation scattering is reduced in the DH-structure. -- Abstract: This is a theoretical study of AlGaN/AlN/GaN/AlGaN double heterojunction (DH) structure with AlGaN as buffer layer. Our calculation shows that as the buffer Al content increases, though two-dimensional electron gas (2DEG) sheet density decreases, the channel back-barrier caused by polarization-induced electric field in GaN provides better electron confinement. And under certain conditions the DH-structure shows bipolar characteristics, with an additional two-dimensional hole gas (2DHG) formed at GaN/AlGaN interface. The influence of the buffer Al content and GaN channel thickness on the 2DEG and 2DHG sheet densities are investigated, and the conditions for the disappearance of 2DHG are discussed. Also, the mobility inhibited by dislocation scattering is enhanced in DH-structure due to the enhancement of screening effect of the 2DEG

  14. The code of light: al-ghazali and al-suhrawardi

    OpenAIRE

    Gediminaitė, Barbora

    2017-01-01

    The Code of Light: Al-Ghazali and Al-Suhrawardi The Bachelor’s thesis The Code of Light in Islam: al-Ghazali and al-Suhrawardi presents a comparative study of light. The study analyses the philosophical systems of al-Ghazali and al-Suhrawardi through the reconstruction of the image of light and its operation principles. The main subject of the thesis are the attributes of light. The main problem of the research is the semantics and contextuality of light in Islamic theology and philosophy. Th...

  15. Recubrimientos de materiales compuestos metal-cerámico obtenidos por nuevas tecnologías de proyección térmica: Proyección fría (CGS y su resistencia al desgaste

    Directory of Open Access Journals (Sweden)

    Miguel, J. M.

    2011-10-01

    Full Text Available In this paper, composite coatings composed by an aluminum bronze metal matrix and a hard ceramic alumina phase obtained by cold spray technique were obtained in order to increase the tribological properties of the pure bronze coatings. The different processes that occur during the coating formation (hardening of the metal particles, fragmentation of the ceramic particles, shot peening on the metal substrate, etc are described and their effects on the coating properties are studied. Wear tests consisting on Ball-on-Disk tests, abrasion Rubber Wheel tests and erosion tests as well as microhardness and adhesion tests are carried out and the results are correlated with the ceramic phase content of the coatings. It can be concluded that the hard ceramic phase increases the tribological properties with relation of the initial bronze coating. Finally, main wear mechanisms during the tribological tests are described. Keywords

    En este artículo se utiliza la técnica de proyección fría (Cold Gas Spray -CGS- para la obtención y caracterización de materiales compuestos constituidos por una matriz metálica de bronce de aluminio y una fase cerámica de alúmina con la intención de mejorar la resistencia al desgaste de los recubrimientos de bronce metálico puros. Se describen los diferentes procesos que ocurren durante la formación del recubrimiento (acritud de las partículas metálicas, rotura de las partículas cerámicas, efecto de granallado sobre el substrato metálico, entre otros y se analizan cuáles son sus consecuencias sobre las propiedades del recubrimiento. Se han realizado ensayos de desgaste por fricción (ensayo Ball-on-Disk, abrasión (Rubber Wheel y erosión, así como se ha determinado la microdureza y adherencia, y correlacionando los resultados obtenidos con el contenido de fase cerámica del recubrimiento. Se concluye que la fase cerámica reforzante incrementa sustancialmente las propiedades tribológicas con relaci

  16. Pemikiran Filosofis Sadra Dalam Tafsir Al-Qur’an Al-Karim : Surah Al-’A‘la

    Directory of Open Access Journals (Sweden)

    Kerwanto Kerwanto

    2014-12-01

    Full Text Available Abstrak : Dalam tafsir atas Surah al-’A‘lā, Mulla Sadra, melalui karyanya Tafsīr al Qur’ān al-Karīm, mengajak jiwa kita berpetualang menuju lapisan makna terdalam untuk mengenali realitas ketauhidan (al- mabdā’, kenabian (shirāth atau nubuwwah dan kebangkitan (ma‘ād dan mengulasnya secara filosofis. Penelitian ini merupakan suatu upaya untuk menggali manfaat dari aspek-aspek penting dari sumber-sumber keagamaan yang tergali dari petunjuk al Qur’an yang berpadu dengan prinsip- prinsip rasional filosofis dan pengalaman mistik (intuitif Sadra. Setiap bab pada tafsir ini diberikan judul dengan tasbīḥ (pernyataan pemujian dan pensucian, dengan tetap memaparkan beragam pokok persoalan terkait metafisika al-Qur’an. Prinsip-prinsip filosofis yang digunakan dalam risalah tafsir ini bisa menjadi salah satu bukti ketidakberjarakan antara filsafat dengan teks-teks keagamaan. Sadra menggunakan metode tafsir yang tetap menerima sisi lahiriah al-Qur’an, dan selanjutnya mencari misteri-misteri, rahasia-rahasia, dan dengan bantuan intelek (akal, intuisi dan iluminasi Tuhan untuk memperoleh realitas-realitas dan makna- makna dibalik selaput ekternalnya (aspek literalnyaKata kunci : Ḥikmah Muta’āliyah, irfan, al-mabdā’, kebangkitan setelah mati, nubuwwah, takwīl, gerak substansial (ḥarakah jawhariyyah, denotasi utama (al-maqshūd al-ashlī, penyempurnaan diri (takammul, tasbīḥ.  Abstract : In his commentary on Surah al-’ A‘lā, Mulla Sadra, through his Tafsīr al-Qur’ān al-Karīm invites our souls to ventureinto the deepest layers of meaning to recognize the reality of Divinity (al- mabdā’, prophethood (Ṣirāṭ or nubuwwah and resurrection (ma‘ād and discusses it in a more philosophical manner. This study is an attempt to explore the benefits of these important aspects of religious sources unearthed from Qur’anic injunctions combined with rational principles of philosophical and mystical experiences

  17. A united refinement technology for commercial pure Al by Al-10Ti and Al-Ti-C master alloys

    International Nuclear Information System (INIS)

    Ma Xiaoguang; Liu Xiangfa; Ding Haimin

    2009-01-01

    Because flake-like TiAl 3 particles in Al-Ti-C master alloys prepared in a melt reaction method dissolve slowly when they are added into Al melt at 720 deg. C, Ti atoms cannot be released rapidly to play the assistant role of grain refinement, leading to a poor refinement efficiency of Al-Ti-C master alloys. A united refinement technology by Al-10Ti and Al-Ti-C master alloys was put forward in this paper. The rational combination of fine blocky TiAl 3 particles in Al-10Ti and TiC particles in Al-Ti-C can improve the nucleation rate of α-Al. It not only improves the grain refinement efficiency of Al-Ti-C master alloys, but also reduces the consumption

  18. Liquidus projection of the Nb-Cr-Al system near the Al3(Nb,Cr) + Cr(Al,Nb) eutectic region

    International Nuclear Information System (INIS)

    Souza, S.A.; Ferrandini, P.L.; Nunes, C.A.; Coelho, A.A.; Caram, R.

    2006-01-01

    The system Nb-Cr-Al was investigated in the region near the Al 3 (Nb,Cr) + Cr(Al,Nb) eutectic and the liquidus projection of that region was determined based on the microstructural characterization of arc melted alloys. The characterization utilized scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), differential thermal analysis (DTA) and X-ray diffraction (XRD). The results allowed one to determine three primary solidification liquidus surfaces ((Cr,Al) 2 Nb, Cr(Al,Nb) and Al 3 (Nb,Cr)), that are originated from the binary systems Cr-Nb, Cr-Al and Al-Nb. It is proposed the occurrence of the invariant reaction L + (Cr,Al) 2 Nb ↔ Al 3 (Nb,Cr) + Cr(Al,Nb) and of a point of minimum, which involves a three phase reaction, L ↔ Al 3 (Nb,Cr) + Cr(Al,Nb). All alloys studied showed formation of the Al 3 (Nb,Cr) + Cr(Al,Nb) eutectic as the last solidification step with Al(Nb)Cr 2 precipitating from Cr(Al,Nb)

  19. A united refinement technology for commercial pure Al by Al-10Ti and Al-Ti-C master alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ma Xiaoguang [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Liu Xiangfa [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China)], E-mail: xfliu@sdu.edu.cn; Ding Haimin [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China)

    2009-03-05

    Because flake-like TiAl{sub 3} particles in Al-Ti-C master alloys prepared in a melt reaction method dissolve slowly when they are added into Al melt at 720 deg. C, Ti atoms cannot be released rapidly to play the assistant role of grain refinement, leading to a poor refinement efficiency of Al-Ti-C master alloys. A united refinement technology by Al-10Ti and Al-Ti-C master alloys was put forward in this paper. The rational combination of fine blocky TiAl{sub 3} particles in Al-10Ti and TiC particles in Al-Ti-C can improve the nucleation rate of {alpha}-Al. It not only improves the grain refinement efficiency of Al-Ti-C master alloys, but also reduces the consumption.

  20. United modification of Al-24Si alloy by Al-P and Al-Ti-C master alloys

    Institute of Scientific and Technical Information of China (English)

    韩延峰; 刘相法; 王海梅; 王振卿; 边秀房; 张均艳

    2003-01-01

    The modification effect of a new type of Al-P master alloy on Al-24Si alloys was investigated. It is foundthat excellent modification effect can be obtained by the addition of this new type of A1-P master alloy into Al-24Simelt and the average primary Si grain size is decreased below 47 μm from original 225 μm. It is also found that theTiC particles in the melt coming from Al8Ti2C can improve the modification effect of the Al-P master alloy. Whenthe content of TiC particles in the Al-24Si melt is 0.03 %, the improvement reaches the maximum and keeps steadywith increasing content of TiC particles. Modification effect occurs at 50 min after the addition of the Al-P master al-loy and TiC particles, and keeps stable with prolonging holding time.

  1. Nanoporous Al sandwich foils using size effect of Al layer thickness during Cu/Al/Cu laminate rolling

    Science.gov (United States)

    Yu, Hailiang; Lu, Cheng; Tieu, A. Kiet; Li, Huijun; Godbole, Ajit; Kong, Charlie

    2018-06-01

    The roll bonding technique is one of the most widely used methods to produce metal laminate sheets. Such sheets offer interesting research opportunities for both scientists and engineers. In this paper, we report on an experimental investigation of the 'thickness effect' during laminate rolling for the first time. Using a four-high multifunction rolling mill, Cu/Al/Cu laminate sheets were fabricated with a range of thicknesses (16, 40, 70 and 130 μm) of the Al layer. The thickness of the Cu sheets was a constant 300 μm. After rolling, TEM images show good bonding quality between the Cu and Al layers. However, there are many nanoscale pores in the Al layer. The fraction of nanoscale pores in the Al layer increases with a reduction in the Al layer thickness. The finite element method was used to simulate the Cu/Al/Cu rolling process. The simulation results reveal the effect of the Al layer thickness on the deformation characteristics of the Cu/Al/Cu laminate. Finally, we propose that the size effect of the Al layer thickness during Cu/Al/Cu laminate rolling may offer a method to fabricate 'nanoporous' Al sandwich laminate foils. Such foils can be used in electromagnetic shielding of electrical devices and noisy shielding of building.

  2. Structural stability and electronic properties of AlCu3, AlCu2Zr in AlZr3: Stabilnost strukture in elektronske lastnosti AlCu3, AlCu2Zr in AlZr3:

    OpenAIRE

    Cheng, Rong; Wu, Xiao-Yu

    2013-01-01

    First-principles calculations were performed to study the alloying stability and electronic structure of the Al-based intermetallic compounds AlCusub3, AlCusub{2}Zr and AlZrsub3. The results show that the lattice parameters obtained after the full relaxation of the crystalline cells are consistent with the experimental data, and these intermetallics have a strong alloying ability and structural stability due to their negative formation energies and their cohesive energies. A further analysis ...

  3. Remoción de nutrientes mediante coagulantes naturales y químicos en planta de tratamiento de aguas residuales, Valledupar Colombia

    Directory of Open Access Journals (Sweden)

    Damileth Dearmas Duarte

    2015-12-01

    Full Text Available Se evaluó desempeño y eficiencia de dos coagulantes químicos: sulfato de aluminio y policloruro de aluminio (PAC, y dos naturales: moringa (Moringa oleífera y cardón guajiro (Lemaireoreus griseus en la remoción de nutrientes y sedimentos del efluente de la planta de tratamiento de aguas residuales conformado por lagunas de estabilización El Salguero ubicada en el municipio de Valledupar, Cesar, Colombia. Los ensayos se llevaron a cabo con muestras de agua procedentes del río Cesar recogidas en el efluente del sistema de tratamiento. La turbidez varía desde 25 NTU hasta 67 NTU durante la época de desarrollo de la investigación. Se obtuvo que el sulfato de aluminio pese a no alcanzar la turbidez exigida por la normatividad colombiana (Decreto 3930/2010, Articulo N°72 Turbidez ≥ 5 NTU es un coagulante que remueve más del 80% de los parámetros de DQO, DBO y algas. El policloruro de aluminio es adecuado para disminuir significativamente la turbidez y los SST en un 92%, además presentó la mejor viabilidad económica de los tratamientos; y para la disminución de fosforo total resultaron efectivos los tratamientos con coagulantes naturales moringa y cardón, los cuales presentaron una remoción de 90.35%. Se concluye que los coagulantes evaluados presentan un potencial de remoción de los parámetros analizados, los resultados avalan a la Moringa oleífera como una posible alternativa natural en la potabilización de las aguas, ya que garantiza no sólo lograrcon éxito el proceso de coagulación, sino también, la ausencia de residuos

  4. /Cu-Al System

    Science.gov (United States)

    Kish, Orel; Froumin, Natalya; Aizenshtein, Michael; Frage, Nachum

    2014-05-01

    Wettability and interfacial interaction of the Ta2O5/Cu-Al system were studied. Pure Cu does not wet the Ta2O5 substrate, and improved spreading is achieved when relatively a high fraction of the active element (~40 at.% Al) was added. The Al2O3 and AlTaO4 phases were observed at the Ta2O5/Cu-Al interface. A thermodynamic evaluation allowed us to suggest that the lack of wetting bellow 40 at.% Al is due to the presence of a native oxide, which covers the drop. The conditions of the native oxide decomposition and the formation of the volatile Al2O suboxide strongly depend on the vacuum level during sessile drop experiments and the composition of the Cu-Al alloy. In our case, Al contents greater than 40% provides thermodynamic conditions for the formation of Al2O (as a result of Al reaction with Al2O3) and the drop spreading. It was suggested that the final contact angle in the Ta2O5/Cu-Al system (50°) is determined by Ta adsorption on the newly formed alumina interlayer.

  5. Metodologi Kitab Ma‘alim al-Tanzil Karya Al-Bagawiy

    Directory of Open Access Journals (Sweden)

    M. Rusydi Khalid

    2017-12-01

    This study aims to describe the metodology of Ma'a> lim al-tanzi>l book by al-Bagawi. The book is one of the books of exegesis written on the basis of hadith, which by the commentary scholars recognized avoided from heresy and weak hadith. The author of this book is Imam Abu Humaid Hussein bin Mas‘u>d al-Farra>’ Al-Bagawi al-Syafi‘i>, died in the year 510 H. This exegesis book combines the interpretation of the companions, tabi‘i>n, and tabi‘i> tabi‘i>n. Interpretation is broken down with easy, simple, and concise diction choices. The stoning of the interpretation of the salaf scholars without mentioning the sanad as already mentioned in the introduction to his book. This book was first printed in one edition with the exegesis book of Ibn Kas}i>r and al-kha>zin. This book interprets the Qur'an analytically from the beginning to the end of the surah by using the method of interpretation based on the hadith, namely by mentioning the arguments of the hadith sahih, the fatwa of the companions and the tabi‘i>n. The characteristic or purpose of this book is fiqh oriented, which tends to the Shafi‘i fiqh.   Abstrak Tulisan ini mendeskripsikan metode penafsiran dalam kitab Ma’a>lim al-tanzi>l karya al-bagawi. Kitab tafsir ini merupakan salah satu di antara kitab-kitab tafsir yang ditulis berdasarkan riwayat, yang oleh para ulama tafsir diakui terhindar dari bid’ah dan hadis dhaif (lemah. Penulis buku ini adalah Imam Abu Muhammad Husain bin Mas‘u>d al-Farra>‘ al-Bagawi al-Syafi‘i>, wafat pada tahun 510 H. Kitab ini adalah kitab pertengahan yang mengutip penafsiran para Sahabat, ta>bi‘i>n, dan tabi‘i ta>bi‘i>n. Penafsiran diuraikan dengan pilihan diksi yang mudah, sederhana, dan ringkas. Penukilan dari interpretasi ulama salaf tanpa menyebutkan sanad karena telah disebutkan dalam pendahuluan bukunya. Buku ini pertama kali dicetak dalam satu edisi dengan tafsir Ibn Kas\\i>r dan tafsir al-Kha>zin. Kitab ini menafsirkan al-Qur’an secara

  6. ALS Association

    Science.gov (United States)

    ... toward a world without ALS! Walk to Defeat ALS® Walk to Defeat ALS® draws people of all ... We need your help. I Will Advocate National ALS Registry The National ALS Registry is a congressionally ...

  7. AlN nanoparticle-reinforced nanocrystalline Al matrix composites: Fabrication and mechanical properties

    International Nuclear Information System (INIS)

    Liu, Y.Q.; Cong, H.T.; Wang, W.; Sun, C.H.; Cheng, H.M.

    2009-01-01

    To improve the specific strength and stiffness of Al-based composites, AlN/Al nanoparticles were in-situ synthesized by arc plasma evaporation of Al in nitrogen atmosphere and consolidated by hot-pressing to fabricate AlN nanoparticle-reinforced nanocrystalline Al composites (0-39 vol.% AlN). Microstructure characterization shows that AlN nanoparticles homogeneously distribute in the matrix of Al nanocrystalline, which forms atomically bonded interfaces of AlN/Al. The hardness and the elastic modulus of the nanocomposite have been improved dramatically, up to 3.48 GPa and 142 GPa, respectively. Such improvement is believed to result from the grain refinement strengthening and the interface strengthening (load transfer) between the Al matrix and AlN nanoparticles

  8. Comparison of one and two-neutron transfer near the Coulomb barrier for the 27Al(18O, 16O)29Al, 27Al(18O, 17O)28Al and 27Al(13C, 12C)28Al reactions

    International Nuclear Information System (INIS)

    Schiller, S.A.; Eck, J.S.

    1975-01-01

    Total reaction cross sections for the transfer reactions 27 Al( 18 O, 16 O) 29 Al, 27 Al( 18 O, 17 O) 28 Al and 27 Al( 13 C, 12 C) 28 Al are reported for center-of-mass energies between 13 and 20 MeV for 18 O projectiles and between 11 and 17.5 MeV for 13 C projectiles. The reaction products, 29 Al, and 28 Al, beta decay to 29 Si and 28 Si, respectively, and the subsequent γ decays of 29 Si and 28 Si were measured. Due to the relatively long beta decay half lives, data were taken in a beam-off mode, resulting in very clean spectra. Total cross sections were calculated and compared with a theoretical model for barrier penetration proposed by C.Y. Wong. Differences between 18 O induced one and two-neutron total transfer reaction cross sections are discussed. (orig.) [de

  9. Al-matrix composite materials reinforced by Al-Cu-Fe particles

    International Nuclear Information System (INIS)

    Bonneville, J; Laplanche, G; Joulain, A; Gauthier-Brunet, V; Dubois, S

    2010-01-01

    Al-matrix material composites were produced using hot isostatic pressing technique, starting with pure Al and icosahedral (i) Al-Cu-Fe powders. Depending on the processing temperature, the final reinforcement particles are either still of the initial i-phase or transformed into the tetragonal ω-Al0 0.70 Cu 0.20 Fe 0.10 crystalline phase. Compression tests performed in the temperature range 293K - 823K on the two types of composite, i.e. Al/i and Al/ω, indicate that the flow stress of both composites is strongly temperature dependent and exhibit distinct regimes with increasing temperature. Differences exist between the two composites, in particular in yield stress values. In the low temperature regime (T ≤ 570K), the yield stress of the Al/ω composite is nearly 75% higher than that of the Al/i composite, while for T > 570K both composites exhibit similar yield stress values. The results are interpreted in terms of load transfer contribution between the matrix and the reinforcement particles and elementary dislocation mechanisms in the Al matrix.

  10. Piezo-tunnel effect in Al/Al2O3/Al junctions elaborated by atomic layer deposition

    Science.gov (United States)

    Rafael, R.; Puyoo, E.; Malhaire, C.

    2017-11-01

    In this work, the electrical transport in Al/Al2O3/Al junctions under mechanical stress is investigated in the perspective to use them as strain sensors. The metal/insulator/metal junctions are elaborated with a low temperature process (≤200 °C) fully compatible with CMOS back-end-of-line. The conduction mechanism in the structure is found to be Fowler-Nordheim tunneling, and efforts are made to extract the relevant physical parameters. Gauge factors up to -32.5 were found in the fabricated devices under tensile stress. Finally, theoretical mechanical considerations give strong evidence that strain sensitivity in Al/Al2O3/Al structures originates not only from geometrical deformations but also from the variation of interface barrier height and/or effective electronic mass in the tunneling oxide layer.

  11. Generation and evolution of nanoscale AlP and Al{sub 13}Fe{sub 4} particles in Al-Fe-P system

    Energy Technology Data Exchange (ETDEWEB)

    Qiao, Huan; Gao, Tong; Zhu, Xiangzhen; Wu, Yuying; Qian, Zhao; Liu, Xiangfa, E-mail: xfliu@sdu.edu.cn

    2015-02-15

    Highlights: • Diffusion and gradual solid reactions between Al and Fe{sub x}P phases in Al-Fe-P alloy were investigated. • Nanoscale AlP clusters are in-situ generated and evolve during the whole process. • This novel Al-Fe-P alloy has an excellent low-temperature refining performance on hypereutectic Al-Si alloy. - Abstract: In this paper, the gradual solid reactions between Al and Fe{sub x}P phases in Al-Fe-P alloy were investigated. The results show that the whole reaction process undergoes four main stages: the diffusion of Al atom, the generation of (Al, Fe, P) intermediate compound, the precipitation of nano AlP and Al{sub 13}Fe{sub 4} clusters and their growth to submicron particles. The microstructure of Fe-P particles evolves from the “egg-type”, the “sponge-type” to the “sesame-cake” structure. AlP and Al{sub 13}Fe{sub 4} nano phases have in-situ generated and evolved during the whole process. The gradual reaction mechanism has been discussed. Furthermore, a novel Al-Fe-P alloy which contains (Al, Fe, P) intermediate compounds and nano AlP particles has been synthesized and its low-temperature refining performance on A390 alloy has also been investigated.

  12. Japanese version of the ALS-FTD-Questionnaire (ALS-FTD-Q-J).

    Science.gov (United States)

    Watanabe, Yasuhiro; Beeldman, Emma; Raaphorst, Joost; Izumi, Yuishin; Yoshino, Hiide; Masuda, Michihito; Atsuta, Naoki; Ito, Satoru; Adachi, Tadashi; Adachi, Yoshiki; Yokota, Osamu; Oda, Masaya; Hanashima, Ritsuko; Ogino, Mieko; Ichikawa, Hiroo; Hasegawa, Kazuko; Kimura, Hideki; Shimizu, Toshio; Aiba, Ikuko; Yabe, Hayato; Kanba, Makoto; Kusumi, Kimiyoshi; Aoki, Tetsuya; Hiroe, Yu; Watanabe, Hirohisa; Nishiyama, Kazutoshi; Nomoto, Masahiro; Sobue, Gen; Nakashima, Kenji

    2016-08-15

    Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) share common clinical, genetic and neuropathological features. Some ALS patients have behavioral/personality changes, which could result in significant obstacles in the care provided by family members and caregivers. An easy screening tool would contribute greatly to the evaluation of these symptoms. We translated the ALS-FTD-Questionnaire, developed in the Netherlands, into Japanese (ALS-FTD-Q-J) and examined the clinimetric properties (internal consistency, construct and clinical validity). Patients with ALS and/or behavioral variant FTD (bvFTD) were evaluated alongside healthy controls in this multicenter study. All ALS patients, regardless of bvFTD status, were further evaluated by the frontal behavioral inventory (FBI) and for frontal/executive function, cognition, anxiety/depression, and motor functions. Data from 146 subjects were analyzed: ALS (92), ALS-bvFTD (6), bvFTD (16), and healthy controls (32). The internal consistency of the ALS-FTD-Q-J was good (Cronbach α=0.92). The ALS-FTD-Q-J showed construct validity as it exhibited a high correlation with the FBI (r=0.79). However, correlations were moderate with anxiety/depression and low with cognitive scales, in contrast to the original report, i.e. a moderate correlation with cognition and a low correlation with anxiety/depression. The ALS-FTD-Q-J discriminated ALS patients from (ALS-)bvFTD patients and controls. Thus, the ALS-FTD-Q-J is useful for evaluating Japanese ALS/FTD patients. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Radiation detection with Nb/Al-AlOx/Al/Nb superconducting tunnel junctions

    International Nuclear Information System (INIS)

    Matsumura, Atsuki; Takahashi, Toru; Kurakado, Masahiko

    1992-01-01

    Superconductor radiation detectors have the possibility of 20-30 times better energy resolution than that of a high resolution Si detector. We fabricated Nb/Al-AlOx/Al/Nb superconducting tunnel junctions with low leakage current. X rays were detected with large area junctions of 178x178 μm 2 . High energy resolution of 160 eV for 5.9 keV was obtained. We also fabricated series connected junctions which covers a rather large area of 4x4 mm 2 . α particles injected into the rear substrate were detected using nonthermal phonons induced by the radiations in the substrate. (author)

  14. ALS-Plus Syndrome: Non-Pyramidal Features in a Large ALS Cohort

    Science.gov (United States)

    McCluskey, Leo; Vandriel, Shannon; Elman, Lauren; Van Deerlin, Vivianna M.; Powers, John; Boller, Ashley; Wood, Elisabeth McCarty; Woo, John; McMillan, Corey T.; Rascovsky, Katya; Grossman, Murray

    2014-01-01

    Objective Autopsy studies show widespread pathology in amyotrophic lateral sclerosis (ALS), but clinical surveys of multisystem disease in ALS are rare. We investigated ALS-Plus syndrome, an understudied group of patients with clinical features extending beyond pyramidal and neuromuscular systems with or without cognitive/behavioral deficits. Methods In a large, consecutively-ascertained cohort of 550 patients with ALS, we documented atypical clinical manifestations. Genetic screening for C9orf72 hexanucleotide expansions was performed in 343 patients, and SOD1, TARDBP, and VCP were tested in the subgroup of patients with a family history of ALS. Gray matter and white matter imaging was available in a subgroup of 30 patients. Results Seventy-five (13.6%) patients were identified with ALS-Plus syndrome. We found disorders of ocular motility, cerebellar, extrapyramidal and autonomic functioning. Relative to those without ALS-Plus, cognitive impairment (8.0% vs 2.9%, p=0.029), bulbar-onset (49.3% vs 23.2%, pALS-Plus. Survival was significantly shorter in ALS-Plus (29.66 months vs 42.50 months, p=0.02), regardless of bulbar-onset or mutation status. Imaging revealed significantly greater cerebellar and cerebral disease in ALS-Plus compared to those without ALS-Plus. Conclusions ALS-Plus syndrome is not uncommon, and the presence of these atypical features is consistent with neuropathological observations that ALS is a multisystem disorder. ALS-Plus syndrome is associated with increased risk for poor survival and the presence of a pathogenic mutation. PMID:25086858

  15. Validación de un método analítico para la determinación cuantitativa de parabenos en el gel de hidróxido de aluminio Validation of an analytical method for the quantitative determination of parabens in aluminum hydroxide gel

    Directory of Open Access Journals (Sweden)

    Ernesto Benítez Hechavarría

    2006-08-01

    Full Text Available Se realizó la valoración prospectiva de un método desarrollado para la cuantificación de metil y de propil parabeno en el gel de hidróxido de aluminio mediante cromatografía líquida de alta resolución en fase reversa, con columna RP18 (25* 0,4 cm y detector UV-Visible a 254 nm. Se evaluaron los parámetros especificidad, linealidad, precisión, exactitud, y adecuación cromatográfica. Los resultados obtenidos mostraron que el método cumple con las especificaciones establecidas para cada parámetro evaluado, lo cual indicó que es un método rápido, seguro y confiable para la determinación cuantitativa de los parabenos en este gelThe prospective assessment of a method developed for the quantification of methyl/propyl paraben in aluminum hydroxide gel by reverse-stage high resolution liquid chromatography on RP18 column (25*0.4 cm, and with UV detector visible at 254 nm, was made. The specificity, lineality, accuracy, exactness and chromatographic adequacy were evaluated The results obtained showed that the method meets the specifications established for each evaluated parameter, which indicates that it is a rapid, safe and reliable method for the quantitative determination of the parabens in this gel

  16. Tailoring ultrafine grained and dispersion-strengthened Ti 2 AlC/TiAl ...

    Indian Academy of Sciences (India)

    In situ Ti 2 AlC/TiAl composite was fabricated by hot-pressing method via the reaction system of Ti 3 AlC 2 and Ti-Al pre-alloyed powders at low temperature of 1150 ∘ C. The composite mainly consisted of TiAl, Ti 3 Al and Ti 2 AlC phases. Fine Ti 2 AlC particles were homogeneously distributed and dispersed in the matrix.

  17. Assessing behavioural changes in ALS: cross-validation of ALS-specific measures.

    Science.gov (United States)

    Pinto-Grau, Marta; Costello, Emmet; O'Connor, Sarah; Elamin, Marwa; Burke, Tom; Heverin, Mark; Pender, Niall; Hardiman, Orla

    2017-07-01

    The Beaumont Behavioural Inventory (BBI) is a behavioural proxy report for the assessment of behavioural changes in ALS. This tool has been validated against the FrSBe, a non-ALS-specific behavioural assessment, and further comparison of the BBI against a disease-specific tool was considered. This study cross-validates the BBI against the ALS-FTD-Q. Sixty ALS patients, 8% also meeting criteria for FTD, were recruited. All patients were evaluated using the BBI and the ALS-FTD-Q, completed by a carer. Correlational analysis was performed to assess construct validity. Precision, sensitivity, specificity, and overall accuracy of the BBI when compared to the ALS-FTD-Q, were obtained. The mean score of the whole sample on the BBI was 11.45 ± 13.06. ALS-FTD patients scored significantly higher than non-demented ALS patients (31.6 ± 14.64, 9.62 ± 11.38; p ALS-FTD-Q was observed (r = 0.807, p ALS-FTD-Q. Good construct validity has been further confirmed when the BBI is compared to an ALS-specific tool. Furthermore, the BBI is a more comprehensive behavioural assessment for ALS, as it measures the whole behavioural spectrum in this condition.

  18. Plastic deformation of Al13Fe4 particles in Al-Al13Fe4 by high-speed compression

    International Nuclear Information System (INIS)

    Yoneyama, N.; Mizoguchi, K.; Kumai, S.; Sato, A.; Kiritani, M.

    2003-01-01

    Spray-formed Al-Fe alloys having undergone high-speed deformation were examined under a high-voltage electron microscope. Two types of specimens were examined; one containing fine Al 13 Fe 4 particles, and the other containing large particles. In the former specimen, deformation is found to proceed in three patterns, depending on specimen thickness and strain rate: (1) without deformation of the Al 13 Fe 4 ; (2) breaking of the Al 13 Fe 4 ; or (3) melting of the Al 13 Fe 4 . Local melting is found to alter some of the Al 13 Fe 4 particles, to impart five-fold symmetry in diffraction or an amorphous structure. In the latter specimen, introduction of glide dislocations enabled us to determine a shear system in the mc102 monoclinic c2/m crystal of Al 13 Fe 4 . On the bases of these observations, the mechanism of high-speed deformation is discussed while taking into account the highly stressed and/or heated states of Al 13 Fe 4 embedded in Al matrix

  19. Synthesis and characterization of pillared bentonite with Al, AL/Fe and impregnated with Pd; Sintese e caracterizacao de bentonitas pilarizadas com Al, AL/Fe e impregnadas com Pd

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Marcus Vinicius Costa; Pizarro, Alejandro Herrero; Molina, Carmen Belen, E-mail: marcus.ufpa@yahoo.com.br [Universidade Federal do Para (UFPA), Belem, PA (Brazil). Instituto de Tecnologia. Faculdade de Engenharia Quimica; Seccion de Ingenieria Quimica, Facultad de Ciencias, Universidad Autonoma de Madri (Spain)

    2017-10-01

    In this work, a north american bentonite was pillared with Al and Al/Fe, creating the Al-PILC and Al-Fe-PILC, respectively. Then the Pd was impregnated in the materials, generating Pd-Al-PILC and Pd-Al-Fe-PILC, respectively. The samples were characterized by X-ray diffraction, differential thermal analysis and thermogravimetric and N{sub 2} adsorption at 77 K to determine the specific surface area by BET method (Brunauer - Emmett - Teller). There was an increase in the basal spacing of bentonite from 12.4Å in the original sample to 17.81Å in the Al-Fe-PILC, 17.20Å in Pd-Al-PILC and 17.05Å in the Pd-Al-Fe-PILC. The specific surface area increased from 19.05m{sup 2}/g in the original sample to 173.49m{sup 2}/g in Al-Fe-PILC, 101.31m{sup 2}/g to Pd-Al-PILC and 92m{sup 2}/g in Pd-Al-Fe-PILC. The pillaring process was successful and the synthesized materials have great potential for use as catalysts. (author)

  20. Electrodeposition of Al from a 1-butylpyrrolidine-AlCl3 ionic liquid

    Directory of Open Access Journals (Sweden)

    Giridhar Pulletikurthi

    2015-12-01

    Full Text Available The addition of 1-butylpyrrolidine to AlCl3 results in the formation of an electrolyte that is suited to Al deposition. The feasibility of electrodepositing Al from the synthesized electrolyte was investigated. Several compositions of AlCl3 and 1-butylpyrrolidine were prepared for this purpose. These mixtures show a different phase behavior at various compositions of AlCl3 and 1-butylpyrrolidine. IR, Raman and NMR spectroscopy were employed to characterize the synthesized liquids. Among the prepared compositions, 1:1.2 mol ratio of 1-butylpyrrolidine:AlCl3 and the upper phase of 1:1.3 mol ratio of 1-butylpyrrolidine:AlCl3 were found to be suitable for Al electrodeposition at room temperature (RT. Uniform and thick (~µm thick layers of Al were obtained on copper at RT. Al deposition occured from the cationic species of AlCl3−xLy+ (where x≤2, y=1–2, and L=1-butylpyrrolidine in this electrolyte. This behavior is contrary to the well investigated classic AlCl3 based ionic liquids, where the deposition of Al occurs mainly from anionic Al2Cl7− ions.

  1. Orientation of Al3Ti platelets in Al-Al3Ti functionally graded material manufactured by centrifugal method

    International Nuclear Information System (INIS)

    Watanabe, Y.; Fukui, Y.

    1997-01-01

    Al-Al 3 Ti functionally graded materials (FGMs) were manufactured by the centrifugal method with a commercial ingot of Al-5 mass% Ti master alloy. The alloy was melted at a liquid/solid coexisting temperature, at which Al 3 Ti remains as a solid, and then it was cast into a thick-walled ring. It was found that the Al-Al 3 Ti functionally graded material can be successfully fabricated by the centrifugal method. It was also found that the volume fraction of the Al 3 Ti can be increased by repetition of the centrifugal method. Since the shape of Al 3 Ti particles in a commercial alloy ingot is that of a platelet, the Al 3 Ti particles are arranged with their platelet planes nearly perpendicular to the radial direction. The orientation effects become stronger when the G number becomes larger. Although the final centrifugal casting was conducted under a very large centrifugal force for the specimen cast three times, the orientation effects were weaker than those in the specimen cast one time. From these observations, it is concluded that the origin of orientation of Al 3 Ti platelets can be attributed to the angular velocity gradient of the melt along the radial direction produced by the difference in the viscosity. (orig.)

  2. In situ synthesis of Ti{sub 2}AlC–Al{sub 2}O{sub 3}/TiAl composite by vacuum sintering mechanically alloyed TiAl powder coated with CNTs

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jian [Department of Materials Science and Engineering of Tianjin University, Tianjin Key Laboratory of Composite and Functional Materials, Tianjin 300072 (China); Zhao, Naiqin, E-mail: nqzhao@tju.edu.cn [State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin (China); Department of Materials Science and Engineering of Tianjin University, Tianjin Key Laboratory of Composite and Functional Materials, Tianjin 300072 (China); Nash, Philip [Thermal Processing Technology Center, Illinois Institute of Technology, IL (United States); Liu, Enzuo; He, Chunnian; Shi, Chunsheng; Li, Jiajun [Department of Materials Science and Engineering of Tianjin University, Tianjin Key Laboratory of Composite and Functional Materials, Tianjin 300072 (China)

    2013-11-25

    Highlights: •Using zwitterionic surfactant to enhance the dispersion of the CNTs on the powder surface. •CNTs as carbon source decreased the formation temperature of Ti{sub 2}AlC. •Al{sub 2}O{sub 3} was generated in situ from the oxygen atoms introduced in the drying procedure. •Nanosized Ti{sub 3}Al was precipitated at 1250 °C and distribute in the TiAl matrix homogeneously. •Ti{sub 2}AlC–Al{sub 2}O{sub 3}/TiAl composite was synthesized in situ by sintering pre-alloy Ti–Al coated with CNTs. -- Abstract: Bulk Ti{sub 2}AlC–Al{sub 2}O{sub 3}/TiAl composites were in situ synthesized by vacuum sintering mechanically alloyed Ti–50 at.% Al powders coated with carbon nanotubes (CNTs). The pre-alloyed Ti–50 at.% Al powder was obtained by ball milling Ti and Al powders. The multi-walled carbon nanotubes as the carbon resource were covered on the surface of the pre-alloyed powders by immersing them into a water solution containing the CNTs. A zwitterionic surfactant was used to enhance the dispersion of the CNTs on the powder surface. The samples were cold pressed and sintered in vacuum at temperatures from 950 to 1250 °C, respectively. The results show that the reaction of forming Ti{sub 2}AlC can be achieved below 950 °C, which is 150 °C lower than in the Ti–Al–TiC system and 250 °C lower than for the Ti–Al–C system due to the addition of CNTs. Additionally, the reinforcement of Al{sub 2}O{sub 3} particles was introduced in situ in Ti{sub 2}AlC/TiAl by the drying process and subsequent sintering of the composite powders. Dense Ti{sub 2}AlC–Al{sub 2}O{sub 3}/TiAl composites were obtained by sintering at 1250 °C and exhibited a homogeneous distribution of Ti{sub 2}AlC, Al{sub 2}O{sub 3} and precipitated Ti{sub 3}Al particles and a resulting high hardness.

  3. 27Al NMR studies of NpPd5Al2

    International Nuclear Information System (INIS)

    Chudo, H.; Sakai, H.; Tokunaga, Y.; Kambe, S.; Aoki, D.; Homma, Y.; Shiokawa, Y.; Haga, Y.; Ikeda, S.; Matsuda, T.D.; Onuki, Y.; Yasuoka, H.

    2009-01-01

    We present 27 Al NMR studies for a single crystal of the Np-based superconductor NpPd 5 Al 2 (T c =4.9K). We have observed a five-line 27 Al NMR spectrum with a center line and four satellite lines separated by first-order nuclear quadrupole splittings. The Knight shift clearly drops below T c . The temperature dependence of the 27 Al nuclear spin-lattice relaxation rate shows no coherence peak below T c , indicating that NpPd 5 Al 2 is an unconventional superconductor with an anisotropic gap. The analysis of the present NMR data provides evidence for strong-coupling d-wave superconductivity in NpPd 5 Al 2 .

  4. Study for obtaining a suppressor device of transients using the Al/SRO/Si structure; Estudio para la obtencion de un dispositivo supresor de transitorios utilizando la estructura Al/SRO/Si

    Energy Technology Data Exchange (ETDEWEB)

    Marin Ramos, Heriberto

    1999-06-01

    The circuits and electronic equipment use protective devices against voltage transients. In this work the Aluminium/Oxide structure rich in Silicon/Silicon is presented as another option in the field of transient suppressors devices. Some devices used in the suppression of voltage transients are: zinc oxide varistors, of silicon carbide varistors, selenium cells, and Zener diodes. The Al/SRO/Si structure presents conductive properties due to the presence of excess Silicon in the SRO film. Varying the reacting gases ratio (Ro=N{sub 2}O/SiH{sub 4}) during the growth of the film of Oxide Rich in Silicon (SRO), the conductivity of the material can be varied. The SRO turns out to be of great importance for the suppressor device of transients device that is pretended to be obtained in the present work due to its non-ohmic behavior. The Al/SRO/Si device behaves of several ways depending on the characteristics of the SRO and the silicon substrate. It has been found that one of these behaviors is as a of voltage transients suppressor. Verifying its behavior as transient suppressor, the effects of the film thickness, the area and the excess of silicon of the device were studied, for this purpose the characteristic I-V was obtained, and the obtention of some parameters in DC. In the present work the SRO was obtained by means of LPCVD (Low Pressure Chemical Vapor Deposition), initially a C-V characterization was made to obtain an indicative parameter of excess silicon, such as: permittivity of the SRO film. Also, the refraction index was obtained, which is an indicative parameter of the presence of excess Silicon. Once having the certainty of the presence of excess silicon it was proceed to obtain the I-V characteristic of the Al/SRO/Si structure as a device. The behavior of the Al/SRO/Si structure was analyzed with different parameters, such as: Ro, thickness of the SOR, areas. [Spanish] Los circuitos y equipos electronicos utilizan dispositivos de proteccion contra

  5. Magnetic tunnel junctions with AlN and AlNxOy barriers

    International Nuclear Information System (INIS)

    Schwickert, M. M.; Childress, J. R.; Fontana, R. E.; Kellock, A. J.; Rice, P. M.; Ho, M. K.; Thompson, T. J.; Gurney, B. A.

    2001-01-01

    Nonoxide tunnel barriers such as AlN are of interest for magnetic tunnel junctions to avoid the oxidation of the magnetic electrodes. We have investigated the fabrication and properties of thin AlN-based barriers for use in low resistance magnetic tunnel junctions. Electronic, magnetic and structural data of tunnel valves of the form Ta (100 Aa)/PtMn (300 Aa)/CoFe 20 (20 Aa - 25 Aa)/barrier/CoFe 20 (10 - 20 Aa)/NiFe 16 (35 - 40 Aa)/Ta (100 Aa) are presented, where the barrier consists of AlN, AlN x O y or AlN/AlO x with total thicknesses between 8 and 15 Aa. The tunnel junctions were sputter deposited and then lithographically patterned down to 2 x 2μm 2 devices. AlN was deposited by reactive sputtering from an Al target with 20% - 35% N 2 in the Ar sputter gas at room temperature, resulting in stoichiometric growth of AlN x (x=0.50±0.05), as determined by RBS. TEM analysis shows that the as-deposited AlN barrier is crystalline. For AlN barriers and AlN followed by natural O 2 oxidation, we obtain tunnel magnetoresistance >10% with specific junction resistance R j down to 60Ωμm 2 . [copyright] 2001 American Institute of Physics

  6. A study of the Al-rich part of the Al-Re alloy system

    International Nuclear Information System (INIS)

    Balanetskyy, S.; Grushko, B.

    2008-01-01

    The Al-rich part of the Al-Re phase diagram was reinvestigated by scanning and transmission electron microscopy, powder X-ray diffraction and differential thermal analysis. The earlier reported Al 12 Re, Al 6 Re, and Al 11 Re 4 phases were confirmed. Close to the Al 4 Re composition a high-temperature h-Al 4 Re and a low-temperature l-Al 4 Re phase were found to be formed at slightly different compositions. Both exhibited compositional ranges. A new phase was revealed close to the Al 3 Re composition. The Al 11 Re 4 phase is formed congruently at 1650 deg. C, Al 3 Re peritectically at 1610 deg. C, h-Al 4 Re peritectically at 1410 deg. C, l-Al 4 Re peritectically at ∼1000 deg. C, Al 6 Re peritectically at 813 deg. C and Al 12 Re peritectically at 746 deg. C. Finally, the Al 12 Re-(Al) eutectic is formed at 658 deg. C. The Al 3 Re and h-Al 4 Re are decomposed by eutectoid reactions at ∼946 and 833 deg., respectively. The structure of the h-Al 4 Re phase has not yet been clarified, but it is distinctly different from the Al 4 W phase suggested earlier. The structure of l-Al 4 Re was confirmed. The Al 3 Re phase was found to have a monoclinic structure with a = 0.5180(4) nm, b = 3.97641(9) nm, c = 0.4955(3) nm and β = 99.55(7) o

  7. Abu al-Layth al-Libi

    Science.gov (United States)

    2015-02-01

    success. As an Arab participant acknowledged very early on, “the situation was really harsh. All the brothers were tired,” as they lacked food and... glorious battles that occurred during the early Islamic period.133 He stressed the importance of the battlefield as the path to achieve honor and dignity...diaspora in Waziristan. In the words of Walid Othmani, a French jihadi trained by al-Qa`ida in Waziristan in 2008, “[Al-Libi] was someone well-known and

  8. SAP-like ultrafine-grained Al composites dispersion strengthened with nanometric AlN

    International Nuclear Information System (INIS)

    Balog, M.; Krizik, P.; Yan, M.; Simancik, F.; Schaffer, G.B.; Qian, M.

    2013-01-01

    This paper reports the development of novel Sinter-Aluminum-Pulver (SAP)-like Al–AlN nanocomposites via replacing the native Al 2 O 3 thin films on fine Al powder with a large volume fraction of in situ formed nanometric AlN dispersoids. Fine gas-atomized Al powder (d 50 =1.3 µm) compacts were first partially nitrided at 590 °C in flowing nitrogen, controlled by a small addition of Sn (0.3–0.4 wt%), and subsequently consolidated by hot direct extrusion. The resulting Al–AlN composites consisted of submicrometric Al grains reinforced with nanometric AlN dispersoids together with some nanometric Al 2 O 3 dispersoids. An Al–13 vol% AlN nanocomposite fabricated this way achieved exceptional ultimate tensile strength of 227 MPa, yield strength of 195 MPa and Young's modulus of 66 GPa at 300 °C, superior to typical SAP materials and coarse grained Al–AlN composites. In addition, the Al–13 vol% AlN nanocomposite exhibited good thermal stability up to 500 °C. The strengthening mechanism is discussed

  9. Analisis Kecenderungan Manhaj Akidah Shaykh Shams al-Din al-Sumatera’i

    Directory of Open Access Journals (Sweden)

    MOHD HAIDHAR KAMARZAMAN

    2016-12-01

    Full Text Available Shaykh Shams al-Din al-Sumatera'i is a very great and respected scholar during 16th and 17th century of Acheh. His knowledge in various fields recognized by local and international scholars. He had been a Qadi Malik al-’Adil, a religious leader, who became a referred by communities and country during the reign of the three Sultans of Aceh. He has authored nearly 40 pieces of books related to the theology and sufism. This study focuses on the methods used by Shaykh Shams al-Din al-Sumatera'i in his theological writings. This study found that Shaykh Shams al-Din al-Sumatera'i had used six methods in the such writings.

  10. Ultrasonic spot welding of Al/Mg/Al tri-layered clad sheets

    International Nuclear Information System (INIS)

    Macwan, A.; Patel, V.K.; Jiang, X.Q.; Li, C.; Bhole, S.D.; Chen, D.L.

    2014-01-01

    Highlights: • The optimal welding condition is achieved at 100 J and 0.1 s. • Failure load first increases and then decreases with increasing welding energy. • The highest failure load after welding is close to that of the clad sheets. • At low energy levels failure occurs in the mode of interfacial failure. • At high energy levels failure takes place at the edge of nugget region. - Abstract: Solid-state ultrasonic spot welding (USW) was used to join Al/Mg/Al tri-layered clad sheets, aiming at exploring weldability and identifying failure mode in relation to the welding energy. It was observed that the application of a low welding energy of 100 J was able to achieve the optimal welding condition during USW at a very short welding time of 0.1 s for the tri-layered clad sheets. The optimal lap shear failure load obtained was equivalent to that of the as-received Al/Mg/Al tri-layered clad sheets. With increasing welding energy, the lap shear failure load initially increased and then decreased after reaching a maximum value. At a welding energy of 25 J, failure occurred in the mode of interfacial failure along the center Al/Al weld interface due to insufficient bonding. At a welding energy of 50 J, 75 J and 100 J, failure was also characterized by the interfacial failure mode, but it occurred along the Al/Mg clad interface rather than the center Al/Al weld interface, suggesting stronger bonding of the Al/Al weld interface than that of the Al/Mg clad interface. The overall weld strength of the Al/Mg/Al tri-layered clad sheets was thus governed by the Al/Mg clad interface strength. At a welding energy of 125 J and 150 J, thinning of weld nugget and extensive deformation at the edge of welding tip caused failure at the edge of nugget region, leading to a lower lap shear failure load

  11. Análisis estadístico de los registros de ruido electroquímico obtenidos en la corrosión del aluminio

    Directory of Open Access Journals (Sweden)

    Sánchez, A.

    2005-10-01

    , los cuales pueden reflejar cambios en el mecanismo de corrosión. Sobre todos estos parámetros destaca el uso de la resistencia de ruido. En este trabajo se ha llevado a cabo el tratamiento estadístico de los datos de ENM obtenidos cuando el aluminio es sometido a la acción a tres electrolitos diferentes, que provocan tres tipos distintos de corrosión: el agua destilada (pasividad, una disolución de cloruro de sodio (corrosión por picaduras y una disolución de hidróxido de sodio (corrosión generalizada o uniforme.

  12. KITAB AL-SANĪ AL-MAṬĀLIB: INTERKONEKSI NAHWU DAN TASAWUF

    Directory of Open Access Journals (Sweden)

    Zakiyah Zakiyah

    2012-12-01

    Tulisan ini mereview buku yang berjudul al-Sanī al-Maṭālib yang ditulis oleh Kiai Nur Iman Mlangi Yogyakarta. Buku ini ditulis dalam bahasa Arab yang me­ngandung interkoneksi antara ilmu Nahwu (tata bahasa Arab dengan mis­tisis­me. Buku ini sangat menarik karena kenyataan bahwa kedua pengetahuan tersebut memiliki aturan sendiri-sendiri. Selain itu, sangat sedikit penulis yang menulis dengan gaya seperti itu. Salah satunya adalah Syaikh Abdul Qadir bin Ahmad al-Kuhany dengan karyanya yang berjudul Manniyat al-Fāqir al-Munjarid wa Sayrat al-Murīd al-Mutafarrid. Buku al-Saniy al-Muthalib diduga telah ditulis pada akhir abad ke-18 atau awal abad ke-19, menurut periode kehidupan Kiai Nur Iman yaitu sekitar pertengahan abad ke-18. Aturan Nahwu dalam buku ini dijelaskan secara teosofi yang dimulai dengan penjelasan mengenai tauhid (keesaan Tuhan sebagai kajian dasar bagi orang Islam, yang diikuti dengan makna dari masing-masing aturan bahasa Arab dalam aspek mistiknya.

  13. Rekonstruksi Konsep Ijtihad: Studi Pemikiran Ben’umar tentang al-Ijtihad fi al-Waqi’

    Directory of Open Access Journals (Sweden)

    Duski Ibrahim

    2015-10-01

    Full Text Available This paper is the result of a research that evaluating the reconstruction the concept of ijtihad, by discuss the idea of al-Ijtihad Ben'umar fi al-waqi’. This paper concludes that Al-Ijtihad fi al-waqi’ is actually a form of collective ijtihad (al ijtihad al-jama'i, by gathering the experts of shari'ah law (fuqaha` ash-shar'i and experts Researchers and scientists (khubara` al-'ashr. Because experts know the nash purposes, while researchers and scientists (al-khubara` know the reality (al-waqi’, the effects in the future (ma'alat = future effect and challenges (tahaddiyat. The idea of formulating the concept of al-ijtihad fi al-waqi’ emerged based on a premise that ijtihad is a creation of experts to implement Islamic law in society. Therefore, the concept of ijtihad experienced a significant development, start from using the nash from the language aspects, continue to the using of logic. At the moment when the situation people are increasingly develop, then the creation of ijtihad become a necessary to developed, for example in the form of al-ijtihad fi al-waqi’ . About the source of the formation of the concept of al -ijtihad fi al-waqi’ comes from theory about the functions of nash, al-manath theory in Islamic law, and supported by the theory of al-mashlalah al-mursalah.

  14. Estudio comparativo de la mineralogía y los coloides arcillosos en suelos de trópicos húmedos

    Directory of Open Access Journals (Sweden)

    Juan Bullón Ames

    2014-12-01

    Full Text Available Objetivos: Comparar las diferencias de la composición mineralógica de los suelos de Malasia y Zaire con suelos del Perú, en relación al tipo de coloides arcillosos que poseen. Métodos: Se utilizó el método analítico descriptivo correlacional, siendo las variables: a Tipo de arcillas, b Propiedades físicas del suelo y c Propiedades químicas. Se operacionalizó las variables siendo sus indicadores: Para tipo de arcillas: kaolinitas, halloysitas, Illitas, cloritas y esmectitas; para Propiedades físicas, textura: arena, limo y arcilla; para propiedades químicas: pH, aluminio cambiable, acidez cambiable KCl, acidez cambiable BaCl2 TEA. Para determinar estos indicadores se utilizaron los métodos analíticos siguientes: Termodiferencial y Microscopia electrónica para el tipo de arcillas y los minerales goetita y gibsita. Las propiedades físico-quimicas fueron determinadas por los siguientes métodos: La Granulometría (textura por el método Bouyoucos, pH por potenciometría, el aluminio cambiable por titulación del extracto con KCl, acidez cambiable KCl por el método Yuan, y acidez cambiable BaCl2 TEA por Cloruro de bario. Resultados: Se encontró que los Oxisoles están compuestos por arcillas Kaolinitas y por los minerales: Gibsita y Goetita, mientras que los Ultisoles están conformados por arcillas Illiticas, complejos expandibles esmectíticos, en menor proporción por Kaolinitas. Conclusión: Los Ultisoles presentes en Perú son más fértiles que los Oxisoles.

  15. Efecto de las impurezas en las propiedades físicoquímicas de una solución de lixiviación de minerales de cobre

    Directory of Open Access Journals (Sweden)

    Patricio Navarro

    2016-01-01

    Full Text Available Se cuantificaron y analizaron las propiedades físicas y químicas de una solución de lixiviación de minerales de cobre con una elevada concentración de cloro, aluminio y magnesio. Las propiedades analizadas fueron densidad, viscosidad y oxígeno disuelto. También se evaluó el efecto de la viscosidad sobre el tiempo de separación de fases en extracción por solvente. Las concentraciones utilizadas de cloro fueron 20, 30 y 50 g/L; las de aluminio, 7, 15 y 23 g/L, y las de magnesio, de 6, 14 y 22 g/L. Las temperaturas ensayadas fueron 25, 35 y 45 °C. Los resultados obtenidos muestran que la presencia de impurezas produce un importante impacto en la viscosidad de la solución y solamente pequeños cambios en la densidad. El elemento que menos impacta en estas propiedades es el cloro, seguido del magnesio, y el que produjo mayor cambio fue el aluminio. El aumento de temperatura reduce el impacto de estos elementos. La presencia de impurezas disminuye la concentración de oxígeno disuelto. En extracción por solventes, un aumento en la viscosidad provoca tiempos más prolongados en la separación de fases.

  16. Study of the 26Al(n,p)26Mg and 26Al(n,α)23Na reactions using the 27Al(p,p')27Al inelastic scattering reaction

    International Nuclear Information System (INIS)

    Benamara, S; De Séréville, N; Hammache, F; Stefan, I; Roussel, P; Ancelin, S; Assié, M; Guillot, J; Le Crom, B; Lefebvre, L; Adsley, P; Laird, A M; Barton, C; Diget, C; Fox, S; Coc, A; Deloncle, I; Hamadache, C; Kiener, J; Lefebfre-Schuhl, A

    2016-01-01

    26 Al was the first cosmic radioactivity ever detected in the galaxy as well as one of the first extinct radioactivity observed in refractory phases of meteorites. Its nucleosynthesis in massive stars is still uncertain mainly due to the lack of nuclear information concerning the 26 Al(n,p) 26 Mg and 26 Al(n,α) 23 Na reactions. We report on a single and coincidence measurement of the 27 Al(p,p') 27 Al(p) 26 Mg and 27 Al(p,p') 27 Al(α) 23 Na reactions performed at the Orsay TANDEM facility aiming at the spectroscopy study of 27 Al above the neutron threshold. Fourteen states are observed for the first time within 350 keV above the 26 Al+n threshold. (paper)

  17. AlN/Al dual protective coatings on NdFeB by DC magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Li Jinlong; Mao Shoudong; Sun Kefei [Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Li Xiaomin [Shanghai Institute of Ceramics Chinese Academy of Sciences, Shanghai 200050 (China); Song Zhenlun [Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)], E-mail: songzhenlun@nimte.ac.cn

    2009-11-15

    AlN/Al dual protective coatings were prepared on NdFeB by DC magnetron sputtering in a home-made industrial apparatus. Comparing with Al coating, AlN/Al coatings have a denser structure of an outmost AlN amorphous layer following an inner Al columnar crystal layer. The coatings and NdFeB substrate combine well, and moreover, there is occurrence of metallurgy bonding in the interface layer. Both Al and AlN/Al coatings have a good protective ability to NdFeB. Especially, the corrosion resistance of AlN/Al coated NdFeB is improved largely. AlN/Al and Al protective coatings not only do not deteriorate the magnetic properties of NdFeB, but contribute to their slight increase.

  18. AlN/Al dual protective coatings on NdFeB by DC magnetron sputtering

    International Nuclear Information System (INIS)

    Li Jinlong; Mao Shoudong; Sun Kefei; Li Xiaomin; Song Zhenlun

    2009-01-01

    AlN/Al dual protective coatings were prepared on NdFeB by DC magnetron sputtering in a home-made industrial apparatus. Comparing with Al coating, AlN/Al coatings have a denser structure of an outmost AlN amorphous layer following an inner Al columnar crystal layer. The coatings and NdFeB substrate combine well, and moreover, there is occurrence of metallurgy bonding in the interface layer. Both Al and AlN/Al coatings have a good protective ability to NdFeB. Especially, the corrosion resistance of AlN/Al coated NdFeB is improved largely. AlN/Al and Al protective coatings not only do not deteriorate the magnetic properties of NdFeB, but contribute to their slight increase.

  19. Al-Si/Al2O3 in situ composite prepared by displacement reaction of CuO/Al system

    Directory of Open Access Journals (Sweden)

    Zhang Jing

    2010-02-01

    Full Text Available Al2O3 particle-reinforced ZL109 composite was prepared by in situ reaction between CuO and Al. The microstructure was observed by means of OM, SEM and TEM. The Al2O3 particles in sub-micron sizes distribute uniformly in the matrix, and the Cu displaced from the in situ reaction forms net-like alloy phases with other alloy elements. The hardness and the tensile strength of the composites at room temperature have a slight increase as compared to that of the matrix. However, the tensile strength at 350 ℃ has reached 90.23 MPa, or 16.92 MPa higher than that of the matrix. The mechanism of the reaction in the CuO/Al system was studied by using of differential scanning calorimetry(DSC and thermodynamic calculation. The reaction between CuO and Al involves two steps. First, CuO reacts with Al to form Cu2O and Al2O3 at the melting temperature of the matrix alloy, and second, Cu2O reacts with Al to form Cu and Al2O3 at a higher temperature. At ZL109 casting temperature of 750–780 ℃, the second step can also take place because of the effect of exothermic reaction of the first step.

  20. AlGaN nanocolumns and AlGaN/GaN/AlGaN nanostructures grown by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Ristic, J.; Sanchez-Garcia, M.A.; Ulloa, J.M.; Calleja, E. [Departamento de Ingenieria Electronica, ETSI Telecomunicacion, Universidad Politecnica de Madrid, Ciudad Universitaria, 28040 Madrid (Spain); Sanchez-Paramo, J.; Calleja, J.M. [Departamento de Fisica de Materiales, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Jahn, U.; Trampert, A.; Ploog, K.H. [Paul-Drude-Institut fuer Festkoerperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany)

    2002-12-01

    This work reports on the characterization of hexagonal, single crystal AlGaN nanocolumns with diameters in the range of 30 to 100 nm grown by molecular beam epitaxy on Si(111) substrates. The change of the flux ratio between the Al and the total III-element controls the alloy composition. The Al composition trend versus the Al flux is consistent both with the E{sub 2} phonon energy values measured by inelastic light scattering and the luminescence emission peaks position. High quality low dimensional AlGaN/GaN/AlGaN heterostructures with five GaN quantum discs, 2 and 4 nm thick, embedded into the AlGaN columns, were designed in order to study the quantum confinement effects. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

  1. Influencia de algunas variables del proceso sol–gel en las propiedades texturales y estructurales de un soporte de NiAl2O4

    Directory of Open Access Journals (Sweden)

    Valencia, J. S.

    2004-06-01

    Full Text Available In this work some aspects related to the synthesis of nickel aluminate as a ceramic material by the sol–gel processing, are studied. The solids obtained are analyzed by atomic absorption and x ray flourescence in order to determine their chemical composition. Texture is investigated using N2 adsorption–desorption isotherms, the structure is verified by x ray diffraction, and the morphology is looked using scanning electron microscope. The results show that the hydrolysis of aluminum tri–sec–butoxyde in presence of nickel nitrate at 80 °C and pH 10, produces a xerogel whose treatment at 900 °C results in a bright blue, fine, porous, spinel type solid, NiAl2O4. Texture data of these materials as shown by type IV isotherms with hysteresis loops type E; it verifies that hydrolysis temperature does not influence the surface area and confirms that these solids have a monomodal pore size distribution.En este trabajo se estudian algunos aspectos asociados con la síntesis, mediante procesamiento sol–gel, del aluminato de níquel. A los sólidos obtenidos se les determina la composición elemental mediante absorción atómica y fluorescencia de rayos–X, se les investiga la textura por sortometría de N2 a 77 K, se les analiza la estructura por difracción de rayos–X y se les examina la morfología con microscopía electrónica de barrido. Los resultados muestran que la hidrólisis a 80 °C y pH 10 de tri–sec–butóxido de aluminio en presencia de nitrato de níquel conduce a un xerogel cuyo tratamiento a 900 °C resulta en un sólido azul brillante, finamente dividido, poroso y altamente compatible con la espinela NiAl2O4. La textura de estos materiales se manifiesta por isotermas adsorción–desorción de nitrógeno tipo IV y anillos de histéresis tipo E; se verifica que la temperatura de hidrólisis no ejerce una marcada influencia sobre el área superficial de los sólidos y se comprueba que los sólidos poseen una distribuci

  2. KONSEPSI AL-QURAN DAN AL-HADITS TENTANG OPERASIONAL BANK SYARIAH

    Directory of Open Access Journals (Sweden)

    Muhammad Ardy Zaini

    2015-01-01

    Full Text Available Islam hadir dengan beberapa tujuan, diantaranya adalah terciptanya khoirul ummah dan rahmatan lil’alamin dengan al-Qur’an dan al-Hadits sebagai penuntun umat Islam demi tercapainya tujuan tersebut. Sebagai pedoman hidup, al-Qur’an dan al-Hadits memberikan berbagai petunjuk tentang keteraturan dan permasalahan hidup, termasuk didalamnya mengenai perbankan yang telah memenuhi hampir separuh sisi-sisi kehidupan manusia. Untuk memaksimal ajaran syariah secara kaffah, maka nilai-nilai yang terdapat dalam al-Quran harus mampu diturunkan pada tataran praktis. Salah satu usaha dan langkah dalam rangka menemukan formula perbankan masa depan, al-Quran dan Hadits memiliki konsepsi dalam kegiatan operasional Bank Syariah. Hal ini dilakukan untuk membentuk sikap mental atau watak yang terjabarkan dalam pola berpikir, cara berbicara, dan etika bertingkah laku, sebagai ekspresi jiwa dari manusia yang beriman dan bertakwa kepada Allah Swt. Agar umat Islam mampu menjadi umat yang unggul (khayr ummah.

  3. Fabrication of AlN-TiC/Al composites by gas injection processing

    Institute of Scientific and Technical Information of China (English)

    YU Huashun; CHEN Hongmei; MA Rendian; MIN Guanghui

    2006-01-01

    The fabrication of AlN-TiC/Al composites by carbon-and nitrogen-containing gas injection into Al-Mg-Ti melts was studied. It was shown that AlN and TiC particles could be formed by the in situ reaction of mixture gas (N2+C2H2+NH3) with Al-Mg-Ti melts. The condition for the formation of AlN was that the treatment temperature must be higher than 1373 K, and the amounts of AlN and TiC increased with the increase of the treatment temperature and the gas injection time.It was considered that AlN was formed by the direct reaction of Al with nitrogen-containing gas at the interface of the gas bubble and the melt. However, the mechanism of TiC formation is a combination mechanism of solution-precipitation and solid-liquid reaction.

  4. The formation of AlB2 in an Al-B master alloy

    International Nuclear Information System (INIS)

    Wang Xiaoming

    2005-01-01

    The formation of borides in an Al-3 wt.%B master alloy, produced via chemical reactions of KBF 4 and aluminium has been investigated. The chemical reactions produce boron, which dissolves into molten aluminium and subsequently forms aluminium borides. Backscattered electron imaging (BEI) of the Al-3 wt.%B master alloy under a scanning electron microscope (SEM) revealed the presence of two types of phases that contain different levels of boron. Combined with X-ray diffraction (XRD) results, the two types of phases are identified as AlB 2 on AlB 12 . This gives a direct evidence for a peritectic reaction of AlB 12 and aluminium, which produces AlB 2 . The thermodynamic properties of the reactions that may be involved are examined, and the presence of AlB 12 phase in the master alloy explained. The observed microstructure is explained according to the peritectic reaction in an Al-B phase diagram. The stability of AlB 2 and AlB 12 at lower temperature than 975 deg. C is clarified

  5. Construction and evaluation of multi-component Zn-Al based bearing alloys (Zn-Al-Si, Zn-Al-Cu)

    International Nuclear Information System (INIS)

    Shahmiri, M.; Shahin, K.

    2001-01-01

    Zn-Al based alloys, with excellent mechanical properties, are finding increasing applications in various industries, especially bearing and bushing fields. Observed dimensional instabilities, in their multicomponent systems, (e. g. Zn-Al-Si and, Zn-Al Si-Cu), is believed to be as the result of some kinds of phase transformation, due to the temperature variations, while in service. Profound understanding of the phase transformations due to the temperature variation, requires detailed evaluations of the isothermal sections of the multi-components phase diagrams of Zn-Al-Si and, Zn-Al-Si-Cu alloy systems. In the present article, the isothermal sections of the aforementioned ternary and quaternary systems in the solid state regions have been investigated and observed phase transitions have been critically evaluated

  6. The Existence of a Designer Al=Al Double Bond in the LiAl2 H4- Cluster Formed by Electronic Transmutation.

    Science.gov (United States)

    Lundell, Katie A; Zhang, Xinxing; Boldyrev, Alexander I; Bowen, Kit H

    2017-12-22

    The Al=Al double bond is elusive in chemistry. Herein we report the results obtained via combined photoelectron spectroscopy and ab initio studies of the LiAl 2 H 4 - cluster that confirm the formation of a conventional Al=Al double bond. Comprehensive searches for the most stable structures of the LiAl 2 H 4 - cluster have shown that the global minimum isomer I possesses a geometric structure which resembles that of Si 2 H 4 , demonstrating a successful example of the transmutation of Al atoms into Si atoms by electron donation. Theoretical simulations of the photoelectron spectrum discovered the coexistence of two isomers in the ion beam, including the one with the Al=Al double bond. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Cleanliness distribution of high-carbon chromium bearing steel billets and growth behavior of inclusions during solidification; Distribución y crecimiento de inclusiones en la solidificación de barras de acero para rodamientos con cromo y alto contenido de carbono

    Energy Technology Data Exchange (ETDEWEB)

    Gu, C.; Bao, Y.; Lin, L.

    2017-09-01

    Variation of cleanliness and distribution of inclusions in thickness and width direction of highcarbon chromium bearing steel billets has been studied using total oxygen and nitrogen analysis and SEM/EDS, and the growth behavior of inclusions during solidification was studied with the help of solidification model. The region wit h relatively high total oxygen contents in the cross profile of billets is between inner arc side 3/16 and outer arc side 1/4; between left edge side 5/16 and right edge side 5/16. The formation sequence of inclusions is MgO-Al2O3 > TiN > MnS. MnS could wrap MgO-Al2O3 and reduces the damage to steel matrix caused by the latter, but generally could not effectively wrap TiN. Besides, TiN could wrap MgO-Al2O3 before MnS, which would weaken the protective capacity of MnS. Moreover, compared with MgO-Al2O3 inclusions, the sizes of TiN inclusions are generally larger. Thus the control of TiN inclusions should be strengthened. In hickness direction, the maximum size regions of TiN and MnS inclusions are inner arc side 1/3 and outer arc side 1/3; in width direction, the regions are edge side 1/3. During bearing processing, these regions and the regions with high total oxygen content should be avoided. [Spanish] La distribución de inclusiones en las secciones transversales y longitudinales de barras de acero para rodamientos al cromo con alto contenido de carbono se ha estudiado determinando el contenido total de nitrógeno y oxígeno y mediante SEM/EDS. El crecimiento de inclusiones durante la solidificación se estudió con la ayuda del modelo de solidificación. La zona con contenido total de oxígeno relativamente alto en la sección transversal de las barras, es entre el arco interior de 3/16 y el exterior 1/4; entre el borde izquierdo 5/16 y el derecho 5/16. La secuencia de formación de las inclusiones es MgO-Al2O3 > TiN > MnS. El MnS podría envolver a los óxidos de magnesio y aluminio (MgO-Al2O3) y reducir el daño causado al acero, pero

  8. Oscilaciones de la red de nitruros cúbicos

    Directory of Open Access Journals (Sweden)

    Dario G. Santiago-Pérez

    2009-01-01

    Full Text Available En el trabajo se estudia la dinámica de los nitruros del grupo III en la estructura blenda de zinc utilizando el modelo de cadenas lineales. Utilizando el hecho de que en direcciones de alta simetría las ramas longitudinales de desacoplan de las transversales se reportan las relaciones entre las constantes de fuerza del problema tridimensional (3D y de la cadena lineal equivalente en estas direcciones. También mostramos cómo calcular las constantes de fuerza 3D del masivo (y consecuentemente la matriz dinámica en su totalidad a partir de unos pocos puntos experimentales o teóricos. En particular se determinan las relaciones de dispersión y se calculan las constantes de fuerza de nitruros de Aluminio (AlN y Galio (GaN.

  9. Characterization of N-polar AlN in GaN/AlN/(Al,Ga)N heterostructures grown by metal-organic chemical vapor deposition

    Science.gov (United States)

    Li, Haoran; Mazumder, Baishakhi; Bonef, Bastien; Keller, Stacia; Wienecke, Steven; Speck, James S.; Denbaars, Steven P.; Mishra, Umesh K.

    2017-11-01

    In GaN/(Al,Ga)N high-electron-mobility transistors (HEMT), AlN interlayer between GaN channel and AlGaN barrier suppresses alloy scattering and significantly improves the electron mobility of the two-dimensional electron gas. While high concentrations of gallium were previously observed in Al-polar AlN interlayers grown by metal-organic chemical vapor deposition, the N-polar AlN (Al x Ga1-x N) films examined by atom probe tomography in this study exhibited aluminum compositions (x) equal to or higher than 95% over a wide range of growth conditions. The also investigated AlN interlayer in a N-polar GaN/AlN/AlGaN/ S.I. GaN HEMT structure possessed a similarly high x content.

  10. KRITIK ATAS KRITIK EPISTEMOLOGI TAFSIR M. ABIED AL JABIRI: Studi Kritis atas Madkhal ila al Quran al Karim

    Directory of Open Access Journals (Sweden)

    Ahmad Fawaid

    2015-12-01

    Full Text Available This paper critically views the epistemology of Muhammad Abid al Jabiri’s interpretation in his book, Madkhal ila al Quran al Karim. His latest work is projected to make the Quran relevant to mankind today and with certainly critiquing classical Quranic studies that have been constructed by previous scholars. Starting from Arab criticism, which is expected to synergize the gap between Turath and modernity, al Jabiri tried out his theory in the realm of Quranic studies oriented to maintain its originality and interpretation from sectarian influence. Focusing on al Jabiri’s review on the Quran, this paper examines and associates some of the problems with the epistemology of critique in Arab reasoning. Finally, it is inferred that the epistemologic offer of al Jabiri used in Turath is not fully applicable in Quranic studies for several reasons. First, the Quranic studies existed within the chain of sanad in its formation. Secondly, at the application stage, al Jabri often overlooked the sanad and narrations from the companions.

  11. Lubrication performance and mechanisms of Mg/Al-, Zn/Al-, and Zn/Mg/Al-layered double hydroxide nanoparticles as lubricant additives

    International Nuclear Information System (INIS)

    Li, Shuo; Bhushan, Bharat

    2016-01-01

    Highlights: • Mg/Al-, Zn/Al- and Zn/Mg/Al-layered double hydroxide were synthesized. • Mg/Al-LDH had superior tribological performance compared to other LDHs. • The best thermal stability of Mg/Al-LDH was responsible for its friction property. - Abstract: Solid lubricant particles are commonly used as oil additives for low friction and wear. Mg/Al-, Zn/Al-, and Zn/Mg/Al-layered double hydroxides (LDH) were synthesized by coprecipitation method. The benefits of LDH nanoparticles are that they can be synthesized using chemical methods where size and shape can be controlled, and can be modified organically to allow dispersal in fluids. The LDH nanoparticles were characterized by X-ray diffraction, scanning electron microscope, thermogravimetry, and differential scanning calorimetry. A pin-on-disk friction and wear tester was used for evaluating the friction and wear properties of LDH nanoparticles as lubricant additives. LDH nanoparticles have friction-reducing and anti-wear properties compared to oil without LDHs. Mg/Al-LDH has the best lubrication, possibly due to better thermal stability in severe conditions.

  12. Lubrication performance and mechanisms of Mg/Al-, Zn/Al-, and Zn/Mg/Al-layered double hydroxide nanoparticles as lubricant additives

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shuo [School of Materials Science and Technology, China University of Geosciences (Beijing), 29 Xueyuan Road, Haidian Distract, Beijing 100083 (China); Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics (NLBB), The Ohio State University, 201 W. 19th Avenue Columbus, OH 43210-1142 (United States); Bhushan, Bharat, E-mail: bhushan.2@osu.edu [Nanoprobe Laboratory for Bio- & Nanotechnology and Biomimetics (NLBB), The Ohio State University, 201 W. 19th Avenue Columbus, OH 43210-1142 (United States)

    2016-08-15

    Highlights: • Mg/Al-, Zn/Al- and Zn/Mg/Al-layered double hydroxide were synthesized. • Mg/Al-LDH had superior tribological performance compared to other LDHs. • The best thermal stability of Mg/Al-LDH was responsible for its friction property. - Abstract: Solid lubricant particles are commonly used as oil additives for low friction and wear. Mg/Al-, Zn/Al-, and Zn/Mg/Al-layered double hydroxides (LDH) were synthesized by coprecipitation method. The benefits of LDH nanoparticles are that they can be synthesized using chemical methods where size and shape can be controlled, and can be modified organically to allow dispersal in fluids. The LDH nanoparticles were characterized by X-ray diffraction, scanning electron microscope, thermogravimetry, and differential scanning calorimetry. A pin-on-disk friction and wear tester was used for evaluating the friction and wear properties of LDH nanoparticles as lubricant additives. LDH nanoparticles have friction-reducing and anti-wear properties compared to oil without LDHs. Mg/Al-LDH has the best lubrication, possibly due to better thermal stability in severe conditions.

  13. Dakwah Kultural Bayt al-Qur’an al-Akbar Ukiran Kayu Khas Melayu Palembang

    Directory of Open Access Journals (Sweden)

    Reza Pahlevi

    2016-07-01

    Full Text Available Penelitian ini berusaha mengungkap berbagai fenomena yang menggambarkan serangkaian kegiatan dakwah kultural Bayt al-Qur’an al-Akbar Ukiran Khas Melayu Palembang. Sehingga dapat diperoleh sejumlah informasi mengenai berbagai upaya penerapan program yang dimaksud. Penelitian ini dapat disimpulkan, pertama kontribusi Bayt al-Qur’an al-Akbar Ukiran Khas Melayu Palembang terhadap perkembangan metode dakwah kultural adalah dakwah melalui seni. Kedua, Bayt al-Qur’an al-Akbar Ukiran Khas Melayu Palembang sebagai tempat Wisata Religi yang sangat signifikan.   This research tries to reveal the various phenomenon that describe a series of cultural propaganda activities Bayt al-Qur’an al-Akbar Ukiran Khas Melayu Palembang. In order to obtain some informations about the efforts of the implementation of the program in question. It can be concluded, the first contribution of Bayt al-Qur’an al-Akbar Ukiran Khas Melayu Palembang on the development of methods of cultural propaganda is propaganda through art. Second Bayt al-Qur’an al-Akbar Ukiran Khas Melayu Palembang as a very significant Religious Tourism.

  14. Optical phonon scattering on electronic mobility in Al2O3/AlGaN/AlN/GaN heterostructures

    Science.gov (United States)

    Zhou, X. J.; Qu, Y.; Ban, S. L.; Wang, Z. P.

    2017-12-01

    Considering the built-in electric fields and the two-mode property of transverse optical phonons in AlGaN material, the electronic eigen-energies and wave functions are obtained by solving Schrödinger equation with the finite difference method. The dispersion relations and potentials of the optical phonons are given by the transfer matrix method. The mobility of the two dimensional electron gas influenced by the optical phonons in Al2O3/AlGaN/AlN/GaN heterostructures is investigated based on the theory of Lei-Ting force balance equation. It is found that the scattering from the half-space phonons is the main factor affecting the electronic mobility, and the influence of the other phonons can be ignored. The results show that the mobility decreases with increasing the thicknesses of Al2O3 and AlN layers, but there is no definite relationship between the mobility and the thickness of AlGaN barrier. The mobility is obviously reduced by increasing Al component in AlGaN crystal to show that the effect of ternary mixed crystals is important. It is also found that the mobility increases first and then decreases as the increment of the fixed charges, but decreases always with increasing temperature. The heterostructures constructed here can be good candidates as metal-oxide-semiconductor high-electron-mobility-transistors since they have higher electronic mobility due to the influence from interface phonons weakened by the AlN interlayer.

  15. Al2O3 adherence on CoCrAl alloys

    International Nuclear Information System (INIS)

    Kingsley, L.M.

    1980-04-01

    Adherence of protective oxides on NiCrAl and CoCrAl superalloys has been promoted by a dispersion of a highly oxygen reactive element or its oxide being produced within the protection system. Two aspects of this subject are investigated here: the use of Al 2 O 3 as both the dispersion and protective oxide; and the production of an HfO 2 dispersion while simultaneously aluminizing the alloy. It was found that an Al 2 O 3 dispersion will act to promote the adherence of an external scale of Al 2 O 3 to a degree comparable to previously tested dispersions and an HfO 2 dispersion comparable to that produced by a Rhines pack treatment is produced during aluminization

  16. Tracing Al Shabaab’s Decision to Cooperate with Al Qaeda in Somalia (2008

    Directory of Open Access Journals (Sweden)

    Adlini Ilma Ghaisany Sjah

    2014-02-01

    Full Text Available 'Al Shabaab, a Somali insurgent with predominantly nationalistic causes (alongside transnational [global Jihad] and Islamic goals made the choice to fight on behalf of Al Qaeda in 2008. The decision to do so contrasted with Al Shabaab’s previous behaviour of actively denying cooperation and distancing itself from Al Qaeda. This study aims to uncover factors that contributed to Al Shabaab’s decision through the use of process-tracing. The results show that Al Shabaab’s declaration of cooperation with Al Qaeda in August 2008 was brought about by a series of events that traced back to four factors: public reactions to the implementation of a Salafi ideology, the shift to a radical leadership, Al Shabaab’s inability to maintain stability in areas under its control and its increasing attacks by Al Shabaab on the Somali public. Al Shabaab pursued cooperation with Al Qaeda after realizing that their nationalistic preference was no longer achievable in the near future.' ' '

  17. All About ALS

    Science.gov (United States)

    ... Subscribe August 2015 Print this issue All About ALS Understanding a Devastating Disorder En español Send us ... Sports Concussions Wise Choices How Can I Help ALS Research? If you have ALS, join the National ...

  18. Atomistic simulations of diffusion mechanisms in off-stoichiometric Al-rich Ni3Al

    International Nuclear Information System (INIS)

    Duan, Jinsong

    2007-01-01

    This paper presents dynamics simulation results of diffusion in off-stoichiometric Al-rich Ni 3 Al (Ni 73 Al 27 ) at temperature ranging from 1300 to 1550 K. The interatomic forces are described by the Finnis-Sinclair type N-body potentials. Particular attention is devoted to the effect of the extra 2% of Al atoms sitting on the Ni sublattice as antisite point defects (Al Ni ) on diffusion. Simulation results show that Ni atoms mainly diffuse through the Ni sublattice at the temperatures investigated. Al atoms diffuse via both the intrasublattice and antistructure bridge (ASB) mechanisms. The contribution to Al diffusion from the ASB mechanism decreases at the lower temperature (T Ni ) enhances both Al and Ni diffusion in Ni 73 Al 27 . The Ni-Al coupled diffusion effect is observed and understood at the atomic level for the first time

  19. Methodology and Characteristics of Zad al-masir fi ‘ilm al-tafsirby AllamaIbn al-Jawzī (Urdu

    Directory of Open Access Journals (Sweden)

    Dr. Muhammad Riaz al Azhari

    2017-01-01

    Full Text Available This article describes the methodology and characteristics of Zad al-masir fi ‘ilm al-tafsir. This is one the finest work of AllamaIbn al-Jawzī, a 6th century prominent Interpreter. Several editions of this Tafsir have been published. However, the edition of dar al-kitab al-‘arbi, Beirut published in four volumes is selected for this study. This exegesis is based on conventional narrations, authentic quotations from the Islamic Scholars and lingual & grammatical discussions. As a witness, causes of verses (asbabal-Nuz┴l,Makki and MadaniSurah’s (chapters, the abrogating and abrogated verses (al-nasikhwal-mans┴kh and Islamic jurisprudence have been discussed in it where needed. The quality of this translation which is admirable is that mostly authentic Ahadith from original sources, and references to well known basic books in relevant discussions have been described. `

  20. Phenotypic and genotypic studies of ALS cases in ALS-SMA families.

    Science.gov (United States)

    Corcia, Philippe; Vourc'h, Patrick; Blasco, Helene; Couratier, Philippe; Dangoumau, Audrey; Bellance, Remi; Desnuelle, Claude; Viader, Fausto; Pautot, Vivien; Millecamps, Stephanie; Bakkouche, Salah; Salachas, FranÇois; Andres, Christian R; Meininger, Vincent; Camu, William

    2018-03-01

    Amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA) are the most frequent motor neuron disorders in adulthood and infancy, respectively. There is a growing literature supporting common pathophysiological patterns between those disorders. One important clinical issue for that is the co-occurrence of both diseases within a family. To collect families in which ALS and SMA patients co-exist and describe the phenotype and the genotype of ALS patients. Nine families with co-occurrence of SMA and ALS have been gathered over the last 15 years. Epidemiological, phenotype and genetic status were collected. Out of the nine families, six corresponded to the criteria of familial ALS (FALS). Clinical data were available for 11 patients out of the 15 ALS cases. Mean age of onset was 58.5 years, site of onset was lower limbs in nine cases (81.8%), median duration was 22 months. Four ALS patients carried a mutation: three mutations in SOD1 gene (G147N in two cases and one with E121G) and one repeat expansion in the C9ORF72 gene. Three patients had abnormal SMN1 copy numbers. While the high proportion of familial history of ALS cases in these ALS-SMA pedigrees could have suggested that these familial clusters of the two most frequent MND rely on a genetic background, we failed to exclude that this occurred by chance.

  1. Eutectic microstructures of Al-ThA13 and Al-UA14 alloys

    International Nuclear Information System (INIS)

    Vieira, R.R.; Ambrozio Filho, F.

    1990-01-01

    This paper deals on the microstructures of systems Al-ThAl3 and Al-UAL4, which are composed by a non faceted phase (aluminium) and an intermetallic phase (ThAl3 or UAL4) which is normally faceted phase. (C.M.)

  2. Interface reactions in the Al-Si-SiC and Mg-Al-Al{sub 2}O{sub 3} composite systems

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, P.K. [Commission of the European Communities, Petten (Netherlands). Inst. for Advanced Materials; Fazal-Ur-Rehman [Imperial Coll. of Science, Technology and Medicine, London (United Kingdom). Dept. of Materials; Fox, S. [Imperial Coll. of Science, Technology and Medicine, London (United Kingdom). Dept. of Materials; Flower, H.M. [Imperial Coll. of Science, Technology and Medicine, London (United Kingdom). Dept. of Materials; West, D.R.F.

    1995-12-31

    Structural and compositional observations are reported on the influence of the interfaces on the mechanisms and kinetics of liquid metal-ceramic reactions in Al-SiC, Al-Si-SiC, Mg-Al{sub 2}O{sub 3} and Mg-Al-Al{sub 2}O{sub 3} composites. The aluminium based materials contained up to 20 vol% SiC in particulate form, and were produced by a spray casting process; subsequently the interface reactions were studied in samples heated to temperatures up to 1100 C. The reaction product was Al{sub 4}C{sub 3} in both Al-SiC and Al-Si-SiC composites. The influence of the crystallography and topology of the SiC particle surfaces on the nucleation of the Al{sub 4}C{sub 3} has been demonstrated; surface asperities play an important role. Growth of nuclei proceeds to form continuous reaction product layers which control the subsequent kinetics. The magnesium based composites contained 5 vol% Al{sub 2}O{sub 3} fibres (3 {mu}m in diameter), and were produced by a liquid infiltration process. SD Safimax fibres with relatively low and high porosity, and also RF Saffil fibres, with a silica binder, were investigated. Fibre porosity plays a major role in accelerating the penetration of Mg into the fibres with reaction to form MgO. Silica binder on the fibre surface transforms to MgO. The reaction rate was reduced by the presence of aluminium in the matrix. The factors controlling the reactions in the aluminium and magnesium based composites are compared. (orig.)

  3. KONSTRUKSI FIQH BUKHARI DALAM KITAB AL-JAMI’ AL-SHAHIH

    Directory of Open Access Journals (Sweden)

    Abdul Sattar

    2011-06-01

    Popularitas Imam Bukhari sebagai penyusun kitab Hadits memiliki posisi yang tinggi di kalangan masyarakat muslim. Kitab Al-Jami ‘al-Shahih karya Imam  Bukhari dianggap sebagai koleksi hadits terbaik setelah Quran. Namun, tidak ada banyak informasi tentang kemampuannya di bidang Hukum Islam (fiqh. Ada beberapa pertanyaan yang dapat diajukan dalam hal tersebut;  pertama, apakah pemikiran Imam Bukhari dipengaruh salah satu dari empat fuqaha Sunni saat menulis al-Jami ‘al-Shahih?. Kedua, apa yang diupayakan Imam Bukhari untuk mengartikulasikan pemikirannya tentang hukum Islam? Dengan menggunakan pendekatan eksploratif, verifikatif dan hermenetical, artikel ini akan mengungkapkan bahwa Imam Bukhari tidak berada di bawah pengaruh madhab tertentu dalam mengartikulasikan pemikirannya tentang hukum Islam. Dia mengartikulasikan pandangannya dengan cara yang unik dan execelent berdasarkan kapasitasnya sebagai muhaddits.

  4. La "historia de los omeyas de al-Andalus" en los Masalik al-Absar

    OpenAIRE

    Molina, Luis

    2005-01-01

    [ES]Los Masalik al-absar de Ibn Fadl Allah al-`Umari incluyen un breve resumen de la Historia de los omeyas de al-Andalus. En este trabajo se analizan las relaciones textuales entre ese pasaje y el Muqtabis de Ibn Hayyan, crónica que resulta ser la fuente casi única utilizada por al-`Umari para redactar ese capítulo. [EN]The Masalik al-absar by Ibn Fadl Allah al-`Umari contains a brief summary of the Umayyad history in al-Andalus. In this article, the textual relationship between this p...

  5. Preparación y propiedades de una arcilla montmorillonita pilareada con polihidroxicationes de aluminio Preparation and properties of a montmorillonite clay pillared with aluminium polyhydroxications

    Directory of Open Access Journals (Sweden)

    Sibele B. C. Pergher

    1999-09-01

    Full Text Available Montmorillonite clay from Brazil was pillared with aluminium polyhydroxications. The influence of Al/Mont ratio and calcination temperature in the properties of the prepared materials was studied. Results showed that the pillarization process increases the basal spaces of the natural clay from 9,7 to 18,5Å and the superficial area from 41 to ~230m2/g. The calcination process at different temperatures showed that the pillared material was stable until 600oC but the adequate temperature for calcination was 450oC. Materials prepared with different Al/Mont ratios showed the maximum Al incorporation for ratios >10meq Al/g and a good distribution for rations >15meq Al/g.

  6. Cryptanalysis of Lin et al.'s Efficient Block-Cipher-Based Hash Function

    NARCIS (Netherlands)

    Liu, Bozhong; Gong, Zheng; Chen, Xiaohong; Qiu, Weidong; Zheng, Dong

    2010-01-01

    Hash functions are widely used in authentication. In this paper, the security of Lin et al.'s efficient block-cipher-based hash function is reviewed. By using Joux's multicollisions and Kelsey et al.'s expandable message techniques, we find the scheme is vulnerable to collision, preimage and second

  7. From Kitāb al-ḥadā’iq to Kitāb al-dawā’ir: Reconsidering Ibn al-Sīd al-Batalyawsī’s Philosophical Treatise

    Directory of Open Access Journals (Sweden)

    Eliyahu, Ayala

    2015-06-01

    Full Text Available The philosophical treatise known as Kitāb al-ḥadā’iq is generally ascribed to the 12th century Andalusian author Ibn al-Sīd al-Batalyawsī, although this attribution is sometimes contested. This paper offers a new interpretation of the title, textual history, authorship, sources, and literary genre of this treatise, on the basis of new textual evidence, a reexamination of known evidence, and a comparison between the treatise and Batalyawsī’s works. The conclusions of this study are first, that Kitāb al-ḥadā’iq was not the treatise’s original title, and therefore it should be renamed Kitāb al-dawā’ir; second, that Kitāb al-dawā’ir was originally part of (one of the versions of Batalyawsī’s Kitāb al-masā’il; and third, that the textual and stylistic similarities between this treatise and Batalyawsī’s other works prove the authenticity of the treatise’s attribution to Batalyawsī. In addition, new findings regarding Batalyawsī’s use of formulas from the Rasā’il Ikhwān al-Safā, in Kitāb al-dawā’ir and Kitāb al-masā’il provide further evidence for the deep impact of the Ikhwān on Batalyawsī’s thought, as well as for the close connection between Kitāb al-dawā’ir and Kitāb al-masā’il. This connection is further highlighted according to the attribution of both treatises to the genre of questions and answers in Arabic literature. The evidence gathered in this paper supports the claim that Batalyawsī’s Kitāb al-dawā’ir should be seen as an integral part of his literary oeuvre, as well as of Andalusian philosophical literature in general.Generalmente el tratado filosófico conocido como Kitāb al-ḥadā’iq se asocia al autor andalusí del siglo XII Ibn al-Sid al-Batalyawsī, aunque esta atribución ha sido discutida en ocasiones. Este artículo ofrece una nueva interpretación del título, la historia del texto, la autoría, las fuentes e incluso del género literario al que se

  8. Theory and X-ray Absorption Spectroscopy for Aluminum Coordination Complexes – Al K-Edge Studies of Charge and Bonding in (BDI)Al, (BDI)AlR2, and (BDI)AlX2 Complexes.

    Science.gov (United States)

    Altman, Alison B; Pemmaraju, C D; Camp, Clément; Arnold, John; Minasian, Stefan G; Prendergast, David; Shuh, David K; Tyliszczak, Tolek

    2015-08-19

    Polarized aluminum K-edge X-ray absorption near edge structure (XANES) spectroscopy and first-principles calculations were used to probe electronic structure in a series of (BDI)Al, (BDI)AlX2, and (BDI)AlR2 coordination compounds (X = F, Cl, I; R = H, Me; BDI = 2,6-diisopropylphenyl-β-diketiminate). Spectral interpretations were guided by examination of the calculated transition energies and polarization-dependent oscillator strengths, which agreed well with the XANES spectroscopy measurements. Pre-edge features were assigned to transitions associated with the Al 3p orbitals involved in metal-ligand bonding. Qualitative trends in Al 1s core energy and valence orbital occupation were established through a systematic comparison of excited states derived from Al 3p orbitals with similar symmetries in a molecular orbital framework. These trends suggested that the higher transition energies observed for (BDI)AlX2 systems with more electronegative X(1-) ligands could be ascribed to a decrease in electron density around the aluminum atom, which causes an increase in the attractive potential of the Al nucleus and concomitant increase in the binding energy of the Al 1s core orbitals. For (BDI)Al and (BDI)AlH2 the experimental Al K-edge XANES spectra and spectra calculated using the eXcited electron and Core-Hole (XCH) approach had nearly identical energies for transitions to final state orbitals of similar composition and symmetry. These results implied that the charge distributions about the aluminum atoms in (BDI)Al and (BDI)AlH2 are similar relative to the (BDI)AlX2 and (BDI)AlMe2 compounds, despite having different formal oxidation states of +1 and +3, respectively. However, (BDI)Al was unique in that it exhibited a low-energy feature that was attributed to transitions into a low-lying p-orbital of b1 symmetry that is localized on Al and orthogonal to the (BDI)Al plane. The presence of this low-energy unoccupied molecular orbital on electron-rich (BDI)Al distinguishes

  9. Thermodynamic properties of Al-Mn, Al-Cu, and Al-Fe-Cu melts and their relations to liquid and quasicrystal structure

    International Nuclear Information System (INIS)

    Zaitsev, A I; Zaitseva, N E; Shimko, R Yu; Arutyunyan, N A; Dunaev, S F; Kraposhin, V S; Lam, Ha Thanh

    2008-01-01

    Thermodynamic properties of molten Al-Mn, Al-Cu and Al-Fe-Cu alloys in a wide temperature range of 1123-1878 K and the whole range of concentrations have been studied using the integral effusion method and Knudsen mass spectrometry. Thermodynamic functions of melts were described by the associated solution model. The possibility of icosahedral quasicrystal (i-QC) precipitation from liquid Al-Mn and Al-Cu-Fe alloys was found to be a consequence of the existence in liquid associates (clusters). A geometric model is suggested for the structure of associates in liquid

  10. Sintering Behavior of CNT Reinforced Al6061 and Al2124 Nanocomposites

    Directory of Open Access Journals (Sweden)

    Nouari Saheb

    2014-01-01

    Full Text Available Ball milling and spark plasma sintering were successfully used to produce carbon nanotube reinforced Al6061 and Al2124 nanocomposites which have potential applications in the fields of aerospace, automotive, electronics, and high precision instrumentation. Al2124 and Al6061 nanocomposite powders containing 0.5 to 2 wt.% CNTs prepared through sonication and wet ball milling were spark plasma sintered at 400, 450, and 500°C for 20 minutes under a pressure of 35 MPa. CNTs were better dispersed, and less agglomerated and had good adhesion to the matrix in composites containing 1 wt.% CNTs. The increase of CNT content to 2 wt.% led to the formation of CNT clusters which resulted in less uniform and homogenous composite powders. Almost full densification of Al6061 reinforced with CNTs was achieved at 500°C. Also, CNTs reinforced Al2124 nanocomposites reached very high densities at 500°C. Composites reinforced with 1 wt.% CNTs displayed better densification compared to composites containing 2 wt.% CNTs. The increase of CNTs content from 0.5 to 1 wt.% increased the hardness of the Al6061 and Al2124 alloys to maximum values. Further increase of CNTs content to 2 wt.% decreased the hardness to values lower than that of the monolithic alloys.

  11. Tetragonal phase in Al-rich region of U-Fe-Al system

    International Nuclear Information System (INIS)

    Meshi, L.; Zenou, V.; Ezersky, V.; Munitz, A.; Talianker, M.

    2005-01-01

    A new ternary aluminide U 2 FeAl 20 with the approximate composition Al-4.2at% Fe-8.5at% U was observed in the Al-rich corner of the U-Al-Fe system. Transmission electron microscopy and electron microdiffraction technique were used for characterization of the structure of this phase. It has a tetragonal unit cell with the parameters a=12.4A and c=10.3A and can be described by the space group I4-bar 2m

  12. Ilhaq al-Masa'il bi Nazairiha dan Penerapannya dalam Bahth al-Masa'il

    Directory of Open Access Journals (Sweden)

    Luthfi Hadi Aminuddin

    2013-11-01

    Full Text Available Abstract: Ilh}a>q al-Masa>’il bi Naz}a>iriha is one of the methods used by Nahdlatul Ulama in resisting the opinion based on (manhaji analytical concept of Islamic jurisprudence (the solution for complex social problems as the main purpose of Islamic shari’ah. As known that, up to now, ilh}a>q has been understood as a process of answering a new case by the way of equating to the old one which is written in the book called al-mu’tabarah. Such ilh}a>q has got many criticisms both from the definitions, procedures and its epistemogical footing. This paper is about to reveal how the NU clerics of Islam understand the concept of Ilh}a>q}, what its epistemological footing was and how the concept was applied in discussing many cases (bah}th al-masa>’il. Based on the writer’s study to several documents of decision results of NU that Ilh}a>q did not only simplify to equate the new cases with the old ones that have been freely discussed in the books of al-mu’tabarah, but both cases should have similar legal substance, that is, both should be under the decrees of laws of al-qawa> ‘id al-fiqhi>yah. Thus, Ilh}a>q is actually answering the problem by applying al-qawa>‘id al-fiqhi>yah, whereas the formulation al-qawa>‘id al-fiqhi>yah itself was set off from the examination of a number of furu>’ generated by qiya> s. This paper also found three variations of the implementation of Ilh}a>q in bah}th al-masa>’il. First, the application of Ilh}a>q was without mentioning al-qawa> ‘id al-fiqhi>yah which covered new cases (mulh}aq and the old case law that has been known in the books of fiqh (mulh}aq bih/attached to. Second, the application of Ilh}a>q was accompanied by mentioning mulh}aq bih and al-qawa> ‘id al-fiqhi>yah. Third, the application of Ilh}a>q, was only by the mentioning al-qawa> ‘id al-fiqhi>yah.

  13. Nanoindentation studies of ex situ AlN/Al metal matrix nanocomposites

    International Nuclear Information System (INIS)

    Fale, Sandeep; Likhite, Ajay; Bhatt, Jatin

    2014-01-01

    Highlights: • Formation of in-situ phases nucleated on AlN particles strengthens the matrix. • Formation of in-situ phases increases with AlN content in nanocomposites. • Stronger in-situ phases results in increased hardness and modulus of elasticity. - Abstract: Nanocrystalline Aluminium nitride (AlN) powder is dispersed in different weight ratio in Aluminum matrix to fabricate metal matrix nanocomposite (MMNC) using ex situ melt metallurgy process. The synthesized Al–AlN nanocomposites are studied for phase analysis using high resolution scanning electron microscopy (FEG-SEM) and for hardness behavior using microindentation and nanoindentation tests. Quantitative analysis of the oxide phases is calculated from thermodynamic data and mass balance equation using elemental data obtained from energy dispersive spectroscopy (EDS) results. Role of oxide phases in association with AlN particles is investigated to understand the mechanical behavior of composites using nanoindentation tester. Load–displacement profile obtained from nanoindentation test reveals distribution of oxide phases along with AlN particle and their effect on indent penetration

  14. Isothermal cross-sections of Sr-Al-Ge and Ba-Al-Ge systems at 673 K

    International Nuclear Information System (INIS)

    Kutsenok, N.L.; Yanson, T.I.

    1987-01-01

    X-ray and microstructural analyses are used to study phase equilibria in Sr-Al-Ge and Ba-Al-Ge systems. Existence of SrAl 2 Ge 2 , Sr(Al, Ge) 2 Ba(Al, Ge) 2 , Sr 3 Al 2 Ge 2 , Ba 3 Al 2 Ge 2 ternary compounds is confirmed, a new BaGe 4 binary compound and also new ternary compounds of approximate composition Sr 57 Al 30 Ge 13 and Ba 20 Al 40 Ge 40 , which crystal structure is unknown, are detected. Aluminium solubility in SrAl 4 and BaAl 4 binary compounds (0.05 atomic fraction) is determined. Ba(Al, Ge) 2 compound homogeneity region is defined more exactly (aluminium content varies from 0.27 to 0.51 at. fractions)

  15. Production of 26Al by spallation of Fe, Si, Al nuclei

    International Nuclear Information System (INIS)

    Paillard, P.

    1977-01-01

    Cross sections for 7 Be, 10 Be and 26 Al formation in Al, Si and Fe targets bombarded with 0.6 and 24GeV protons have been measured by using highly selective chemical separation and low level background counters. Results for 26 Al at 0.6GeV are in mb: 17.9 + or - 2.7 in Al, 12.5 + or - 2.5 in Si and 0.45 + or - 0.14 in Fe; at 24GeV 2.6 + or - 0.5mb in Fe. Results for 10 Be are not valid on account of experimental difficulties. It is deduced from these values of aluminium in cosmic ray propagation that 26 Al is not yet cosmic ray chronometer [fr

  16. 143 - 148_Makeri et al.

    African Journals Online (AJOL)

    USER

    2015-06-01

    Jun 1, 2015 ... Yuan et al., 2003), antimicrobial activity (Sundarrao et al., 1993; Betancur-Galvis et al., 1999; Takashi et al., 2006), anti-parasitic, anti-malarial activities (Alali et al., 1998; Jaramillo et al., 2000; Luna et al.,. 2005). This study evaluates the antibacterial activity of extract of stem –bark and leaf extracts of Annona.

  17. Phase relationships in the Al-rich region of the Al-Cu-Er system

    International Nuclear Information System (INIS)

    Zhang Ligang; Masset, Patrick J.; Cao Fuyong; Meng Fangui; Liu Libin; Jin Zhanpeng

    2011-01-01

    Research highlights: → One ternary phase τ 1 -Al 8 Cu 4 Er in Al-rich region with a composition of 59.4-60.4 at.% Al, 32.2-33.8 at.% Cu, and 6.4-7.7 at.% Er is observed in both as-cast and annealed alloys. At 673 K, the binary Al 3 Er phase dissolves about 3.51 at.% Cu. → The calculated solidification paths (based on the CALPHAD method) of as-cast alloys are in agreement with the experimental results. → It can be found that the resultant thermodynamic database can be applied to case studies of as-cast alloys, showing that the literature thermodynamic description of the Al-Cu-Er system is reliable as a working basis for computer-assisted alloy design. - Abstract: The Al-rich region of the ternary Al-Cu-Er system is investigated using the method of X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy. Phase equilibria in the Al-rich region of the Al-Cu-Er system at 673 K have been obtained, and the microstructures of as-cast alloys in the Al-rich region are also investigated. One ternary phase τ 1 -Al 8 Cu 4 Er with a composition of 59.4-60.4 at.% Al, 32.2-33.8 at.% Cu, and 6.4-7.7 at.% Er is observed in both as-cast and annealed alloys. At 673 K, the binary Al 3 Er phase dissolves about 3.51 at.% Cu. The calculated solidification paths (based on the CALPHAD method) of as-cast alloys are in agreement with the experimental results.

  18. Mechanical properties and deformation behavior of Al/Al7075, two-phase material

    International Nuclear Information System (INIS)

    Sherafat, Z.; Paydar, M.H.; Ebrahimi, R.; Sohrabi, S.

    2010-01-01

    In the present study, mechanical properties and deformation behavior of Al/Al7075, two-phase material were investigated. The two-phase materials were fabricated by mixing commercially pure Al powder with Al7075 chips and consolidating the mixture through hot extrusion process at 500 o C. Mechanical properties and deformation behavior of the fabricated samples were evaluated using tensile and compression tests. A scanning electron microscope was used to study the fracture surface of the samples including different amount of Al powder, after they were fractured in tensile test. The results of the tensile and compression tests showed that with decreasing the amount of Al powder, the strength increases and ductility decreases. Calculation of work hardening exponent (n) indicated that deformation behavior does not follow a regular trend. In a way that the n value was approved to be variable and a strong function of strain and Al powder wt% of the sample. The results of the fractography studies indicate that the type of fracture happened changes from completely ductile to nearly brittle by decreasing the wt% of Al powder from 90% to 40%.

  19. A Scholar from Saray: Mawlana Zada al-Sarayi (754/1353–791/1389 in the Biographical Dictionary of Taqi al-Din al-Maqrizi (766/1365–845/1441 “Kitab al-Muqaffa al-Kabir” (The Great Rhymed Book

    Directory of Open Access Journals (Sweden)

    D.R. Zaynuddinov

    2017-03-01

    Full Text Available Research objective: to introduce into academic circulation previously unknown source on the Golden Horde history. Research materials: biographical dictionary of Taqi al-Din al-Maqrizi (766/1365 – 845/1441 “Kitab al-Muqaffa al-Kabir” (The Great Rhymed Book. Results and novelty of the research: This article contains materials from the works of historians engaged in the narrative biography, which V.G. Tiesenhausen did not include in his “Collection of Materials on the Golden Horde history (extract from Arab writings”, although their writings contain very valuable information about the Golden Horde History. Research novelty consists in the fact that the author of this article presents one paragraph from biographical dictionary of Taqi al-Din al-Maqrizi, whose article number 421 provides information about a scholar from Saray – Mawlana Zada al-Sarayi. The author provides its translation and commentary referring to the more than ten medieval Arab sources. After receiving basic education at home, Mawlana Zada al-Sarayi traveled to many Eastern countries in search of knowledge and after having received high recognition he settled in Cairo as a teacher of Sharia Sciences. Despite the fact that his life was interrupted at an early age (36 years, he left a deep mark in science. His son Muhibbu al-Din (Cairo, 791/1389 – Mecca, Friday, the 3rd of Dhu al-Hijjah 859/13 November 1455 also became a great scholar as well as an imam of Sultan al-Ashraf Barsbay himself and other sultans after him. Nisba al-Sarayi sounded on the lips of the Ulema of the East as a symbol of learnedness and high temper. As a result of research it must be said that the study of life of Mawlana Zada al-Sarayi (754/1353 – 791/1389 and the number of migrants from Desht-i Kipchak in Egypt will help researchers in a deeper and more detailed study of the Golden Horde history.

  20. Improved AlGaN/GaN HEMTs Grown on Si Substrates Using Stacked AlGaN/AlN Interlayer by MOCVD

    International Nuclear Information System (INIS)

    Wang Yong; Yu Nai-Sen; Li Ming; Lau Kei-May

    2011-01-01

    AlGaN/GaN high electron mobility transistors (HEMTs) are grown on 2-inch Si (111) substrates by MOCVD. The stacked AlGaN/AlN interlayer with different AlGaN thickness and indium surfactant doped is designed and optimized to relieve the tensile stress during GaN epitaxial growth. The top 1.0μm GaN buffer layer grown on the optimized AlGaN/AlN interlayer shows a crack-free and shining surface. The XRD results show that GaN(002) FWHM is 480 arcsec and GaN(102) FWHM is 900 arcsec. The AGaN/GaN HEMTs with optimized and non-optimized AlGaN/AlN interlayer are grown and processed for comparison and the dc and rf characteristics are characterized. For the dc characteristics of the device with optimized AlGaN/AlN interlayer, maximum drain current density I dss of 737mA/mm, peak transconductance G m of 185mS/mm, drain leakage current density I ds of 1.7μA/mm, gate leakage current density I gs of 24.8 μA/mm and off-state breakdown voltage V BR of 67 V are achieved with L g /W g /L gs /L gd = 1/10/1/1 μm. For the small signal rf characteristics of the device with optimized AlGaN/AlN interlayer, current gain cutoff frequency f T of 8.3 GHz and power gain cutoff frequency f max of 19.9 GHz are achieved with L g /W g /L gs /L gd = 1/100/1/1 μm. Furthermore, the best rf performance with f T of 14.5 GHz and f max of 37.3 GHz is achieved with a reduced gate length of 0.7μm. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  1. Konsepsi Ibnu Jarir Al-Tabari Tentang Al-Qur’an, Tafsir Dan Ta’wil

    Directory of Open Access Journals (Sweden)

    A.M Ismatulloh

    2012-12-01

    Full Text Available The objective of this research is to describe the concept of Ibnu Jarir al-Tabari about al-Qur’an, tafsir and ta’wil. Ibn Jarir al-Tabari is an outstanding expert in the classic Islamic tradition. His knowledge in hadits, fiqh, lughah, history, and tafseer is unquestionable. This study uses an analytical descriptive design. The findings show that: Firstly, in defining al-Qur’an, al-Tabari focused on the al-Qur’an as an Arabic language text, not in other language. Secondly, al-Qur’an is written in sab’ah ahruf. It means that there are 7 different kinds of language with the same meaning. Thirdly, al-Qur’an comes from seven heaven’s door. Fourthly, there is no different word between tafseer and ta’wil. They have same meaning. These concepts are different to other concepts proposed by other ulama.

  2. Interactions between bees and Ludwigia elegans (Camb. Hara (Onagraceae flowers at different altitudes in São Paulo, Brazil

    Directory of Open Access Journals (Sweden)

    Miriam Gimenes

    2002-09-01

    Full Text Available Populations of Ludwigia elegans (Carnb. Hara were examined in Aluminio (600m and Campos do Jordão (1520m, in the State of São Paulo. Flowers of both populations are self-incompatible and dependent on bees for pollination. Flowers of Ludwigia elegans at the Aluminio site were visited by about 30 different species of bees, and those at Campos do Jordão by 10. These results can be related to climatic differences at the two sites, especially temperature, due to their difference in altitude. Inspite of the difference in the absolute number of bee species seen at each site, Tetraglossula anthracina (Michener, 1989 (Colletidae can be considered a specialized and efficient pollinator in both areas, since it visited these flowers frequently and showed many morphological and behavioral adaptations for pollen and nectar collection.

  3. Predicting glass-forming compositions in the Al-La and Al-La-Ni systems

    International Nuclear Information System (INIS)

    Gargarella, P.; de Oliveira, M.F.; Kiminami, C.S.; Pauly, S.; Kuehn, U.; Bolfarini, C.; Botta, W.J.; Eckert, J.

    2011-01-01

    Research highlights: → The glass-forming ability of the Al-La and Al-La-Ni systems was studied using the λ* and the λ.Δe criteria. → Both criteria predicted with just 1% at. of error the best glass-former verified so far in the Al-La system. → Four new glass-former compositions could be predicted in the Al-La-Ni system using the λ.Δe criterion. → The best glass-former reported so far in the Al-La-Ni system was found. - Abstract: In this work, a criterion considering the topological instability (λ) and the differences in the electronegativity of the constituent elements (Δe) was applied to the Al-La and Al-Ni-La systems in order to predict the best glass-forming compositions. The results were compared with literature data and with our own experimental data for the Al-La-Ni system. The alloy described in the literature as the best glass former in the Al-La system is located near the point with local maximum for the λ.Δe criterion. A good agreement was found between the predictions of the λ.Δe criterion and literature data in the Al-La-Ni system, with the region of the best glass-forming ability (GFA) and largest supercooled liquid region (ΔT x ) coinciding with the best compositional region for amorphization indicated by the λ.Δe criterion. Four new glassy compositions were found in the Al-La-Ni system, with the best predicted composition presenting the best glass-forming ability observed so far for this system. Although the λ.Δe criterion needs further refinements for completely describe the glass-forming ability in the Al-La and Al-La-Ni systems, the results demonstrated that this criterion is a good tool to predict new glass-forming compositions.

  4. Electric quadrupole moments of neutron-rich nuclei {sup 32}Al and {sup 31}Al

    Energy Technology Data Exchange (ETDEWEB)

    Kameda, D., E-mail: kameda@ribf.riken.jp; Ueno, H. [RIKEN Nishina Center (Japan); Asahi, K.; Nagae, D.; Takemura, M.; Shimada, K. [Tokyo Institute of Technology, Department of Physics (Japan); Yoshimi, A.; Nagatomo, T.; Sugimoto, T. [RIKEN Nishina Center (Japan); Uchida, M.; Arai, T.; Takase, K.; Suda, S.; Inoue, T. [Tokyo Institute of Technology, Department of Physics (Japan); Murata, J.; Kawamura, H. [Rikkyo University, Department of Physics (Japan); Watanabe, H. [Australian National University, Department of Nuclear Physics (Australia); Kobayashi, Y.; Ishihara, M. [RIKEN Nishina Center (Japan)

    2007-11-15

    The electric quadrupole moments for the ground states of {sup 32}Al and {sup 31}Al have been measured by the {beta} ray-detected nuclear quadrupole resonance method. Spin-polarized {sup 32}Al and {sup 31}Al nuclei were obtained from the fragmentation of {sup 40}Ar projectiles at E/A = 95 MeV/nucleon, and were implanted in a single crystal {alpha}-Al{sub 2}O{sub 3} stopper. The measured Q moment of {sup 32}Al, |Q({sup 32}Al)| = 24(2) mb, is in good agreement with a conventional shell-model calculation with a full sd model space and empirical effective charges, while that of {sup 31}Al is considerably smaller than the sd calculations.

  5. The constitution of alloys in the Al-rich corner of the Al-Si-Sm ternary system

    International Nuclear Information System (INIS)

    Markoli, B.; Spaic, S.; Zupanic, F.

    2001-01-01

    The constitution of alloys and the liquidus surface in the Al-rich corner of the Al-Si-Sm ternary system were determined by the examination of controlled heated and cooled specimens, as well as heat-treated specimens by means of optical and scanning electron microscopy, energy-dispersive X-ray spectroscopy, differential thermal analysis and X-ray diffraction. The Al-rich corner of the Al-Si-Sm ternary system comprises five regions of primary crystallisation (α Al , β Si , Al 3 Sm, Al 2 Si 2 Sm and AlSiSm) with following characteristic invariant reaction sequences: ternary eutectic reaction L → α Al + β Si + Al 2 Si 2 Sm, and two liquidus transition reactions, i. e., L + Al 3 Sm → α Al + AlSiSm, and L + AlSiSm → α Al + Al 2 Si 2 Sm. Along with the position of ternary eutectic and both interstitial points in the Al-rich corner of the Al-Si-Sm ternary system, the temperatures for each reaction were determined. (orig.)

  6. Disordered crystal structure of 20H-AlON, Al10O3N8

    International Nuclear Information System (INIS)

    Banno, Hiroki; Funahashi, Shiro; Asaka, Toru; Hirosaki, Naoto; Fukuda, Koichiro

    2015-01-01

    The disordered crystal structure of 20H-AlON (Al 10 O 3 N 8 ) was determined by combined use of X-ray powder diffraction and transmission electron microscopy. The title compound is hexagonal with space group P6 3 /mmc (Z=2) and the unit-cell dimensions are a=0.307082(5) nm, c=5.29447(8) nm and V=0.432376(12) nm 3 . The structural model showed the positional disordering of three of the six Al sites in the unit cell. The reliability indices calculated from the Rietveld method were R wp =6.97%, S (=R wp /R e )=1.68, R p =5.45%, R B =5.13% and R F =4.56%. We interpreted the disordered structure of 20H-AlON as a statistical average of six different types of ordered structural configurations, which are composed of an octahedral [Al(O, N) 6 ] layer and tetrahedral [Al(O, N) 4 ] layers. We demonstrated the high correlations between the hexagonal unit-cell dimensions and the octahedral layer concentrations for AlON and SiAlON polytypoids. - Graphical abstract: Variations of a and c/(n O +n T ) with n O /(n O +n T ). The a and c are the hexagonal unit-cell dimensions of AlON, SiAlON and AlN. The n O and n T are, respectively, the numbers of octahedral and tetrahedral layers in the unit cells. The unit-cell dimensions in literature are plotted in black plus for AlON and black cross for SiAlON. The unit-cell dimensions of AlN are a=0.3110 nm and c=0.4980 nm. - Highlights: • Crystal structure of Al10O3N8 is determined by laboratory X-ray powder diffraction. • The atom arrangements are represented by the split-atom model. • Six types of ordered atom arrangements are derived from the disordered structure. • Hexagonal unit-cell dimensions changed systematically for AlON and SiAlON compounds

  7. Prinsip Pendidikan Karakter dalam Islam: Studi Komparasi Pemikiran Al-Ghazali dan Burhanuddin Al-Zarnuji

    Directory of Open Access Journals (Sweden)

    Agus Setiawan

    2014-06-01

    Full Text Available The impelemtantion of character education that is done by the Indonesian government recently has been provoked by al-Ghazali and Burhanuddin al-Zarnuji long ago. It was proven by some written thoughts of al-Ghazali and Burhanuddin al-Zarnuji. They were very famous scientists in their era and widely welknown as educational experts who produced some phenomenal thoughts many people use today. Al-Ghazali and Burhanuddin al-Zarnuji lived in the era of Bani Abbasiyah monarchy, but Both of them lived in different era. Al-Ghazali was born first, then Burhanuddin al-Zarnuji. They had different mazhab, al-Ghazali went to the traditional principle of mazhab Syafi’I and Burhanuddin al-Zarnuji went to the modern principle of mazhab Hanafi. The differences, of course, would create a different thought. Still, they might have a similar principle of Islamic character education. The thoughts of character education of al-Ghazali have been poured in the “Ayyuha Walad” focusing to the students’ character building characterized by religiously obedient, skillfull of general and religious knowledge, socially helpful, affectionate, generous, good citizen, and coloring the society. Some applicable thoughts of character education of Ayyuha al-Walad of al-Gazhali to the contemporary education are: the balance of the happiness purposes of the recent life and the life after death, qana’ah and tawakal, affectionate, caring other, patience, honesty, philanthrophy, social works, generousity, democratic, peace makers, and patriotic. Those characters are also directed in the islamic character education nowdays. So that, the thoughts of al-Ghazali positively and responsively are absorbed by the Indonesian government to build the national character widely implementing in the national curriculum based on the local wisdom and the Islamic values. In the end, the students are able to live happily based on the Islamic rules by implementing the good behavior. Similar to the al

  8. Casa-estudio de Luis de Pablo - Madrid – España

    Directory of Open Access Journals (Sweden)

    Fernández Alba, A.

    1973-04-01

    Full Text Available The site is slightly rectangular of about 1,000 m2, near the Sierra de Guadarrama. The house is designed according to an axial pattern: - guests area with three bedrooms; couple's bedroom and toilet; - living area and eating zone; - private studio, with bedroom and bathroom in upper floor. A swimming-pool with a recreation area in the open air and a garage under the living area complete the building. The walls are constructed of precast concrete cross-split units, with insulant and gypsum plaster division. The floors are of reinforced concrete with acoustic absorbing cladding; flat roofing of galvanized sheet; interior floors of moquette and exterior floors of lightweight concrete tiles. The windows are externally of anodized aluminium and internally of formica with aluminium edges.La vivienda ocupa una parcela sensiblemente rectangular de unos 1.000 m2 de superficie, situada cerca de la Sierra de Guadarrama. El programa se ha desarrollado según un esquema axil con tres conceptos diferentes – zona de invitados, con tres dormitorios y su zona de aseo; -zona de estancia, reunión y comidas, y – la zona de estudio privado, con el área de dormitorios y baño situada en un plano superior. Se completa el conjunto con una piscina, unas áreas de expansión al aire libre, y un garaje situado bajo la zona de estancia. Sistema constructivo: muros resistentes de piezas prefabricadas de hormigón seccionadas, con aislante y tabique interior guarnecido y enlucido de yeso; moqueta como revestimiento de los suelos interiores, y losetas de hormigón ligero en la pavimentación de los exteriores, la carpintería en huecos exteriores es de aluminio anodizado, y en el interior, de formica, protegida por cantes de aluminio.

  9. Self-sealing of unsealed aluminium anodic oxide films in very different atmospheres

    Directory of Open Access Journals (Sweden)

    González, J. A.

    2003-12-01

    Full Text Available It is widely believed that the corrosion resistance behaviour of bare aluminium in natural environments is superior to that of unsealed anodised aluminium. However, results obtained in the exposure of unsealed anodised aluminium specimens with three different film thicknesses, in 9 atmospheres of Ibero-America with salinity levels between 3.9 and 517 mg.m-2.d-1 chloride, clearly shows the reverse to be true. After a sufficient time, which is shorter the higher the precipitation rate and the environmental relative humidity, a self-sealing process takes place, leading to coatings that surpass the quality standards demanded in industrial practice. Anodic films, sealed and unsealed, are protective coatings whose quality improves with ageing in most natural environments.

    Está muy difundida la idea de que el comportamiento del aluminio es superior al del aluminio anodizado y sin sellar, desde el punto de vista de la resistencia a la corrosión, en los ambientes naturales. Sin embargo, los resultados obtenidos en la exposición de anodizados sin sellar, de tres espesores diferentes, a 9 atmósferas de Iberoamérica, con salinidades comprendidas entre 3,9 y 517 mg.m-2.d-1 de cloruros, muestran, sin lugar a dudas, lo contrario. Con tiempo suficiente, tanto más rápidamente cuanto mayor sean las precipitaciones y la humedad relativa ambiental, tiene lugar un proceso de autosellado que conduce a recubrimientos que superan las normas de calidad exigidas en la práctica industrial. Los anodizados, sellados y sin sellar, son recubrimientos protectores que mejoran su calidad, en la mayoría de los ambientes naturales, con el envejecimiento.

  10. FRACTIONAL RECRYSTALLIZATION KINETICS IN DIRECTLY COLD ROLLED Al-Mg, Al-Mg-Sc AND Al-Mg-Sc-Zr ALLOY

    Directory of Open Access Journals (Sweden)

    M. S. Kaiser

    2014-12-01

    Full Text Available The evaluation of texture as a function of recrystallization has been characterized for directly cold rolled Al-6Mg, Al-6Mg-0.4Sc and Al-6Mg-0.4Sc-0.2Zr alloys. Samples were annealed isothermally at 400 °C for 1 to 240 minutes to allow recrystallization. Recrystallization kinetics of the alloys is analyzed from the micro-hardness variation. Isothermally annealed samples of aluminum alloys were also studied using JMAK type analysis to see if there exists any correlation between the methods. Recrystallization fraction behavior between two methods the scandium added alloys show the higher variation due to precipitation hardening and higher recrystallization behavior. The scandium and zirconium as a combined shows the more variation due to formation of Al3(Sc, Zr precipitate. From the microstructure it is also observed that the base Al-Mg alloy attained almost fully re-crystallized state after annealing at 400 °C for 60 minutes

  11. Chemical failure modes of AlQ3-based OLEDs: AlQ3 hydrolysis.

    Science.gov (United States)

    Knox, John E; Halls, Mathew D; Hratchian, Hrant P; Schlegel, H Bernhard

    2006-03-28

    Tris(8-hydroxyquinoline)aluminum(III), AlQ3, is used in organic light-emitting diodes (OLEDs) as an electron-transport material and emitting layer. The reaction of AlQ3 with trace H2O has been implicated as a major failure pathway for AlQ3-based OLEDs. Hybrid density functional calculations have been carried out to characterize the hydrolysis of AlQ3. The thermochemical and atomistic details for this important reaction are reported for both the neutral and oxidized AlQ3/AlQ3+ systems. In support of experimental conclusions, the neutral hydrolysis reaction pathway is found to be a thermally activated process, having a classical barrier height of 24.2 kcal mol(-1). First-principles infrared and electronic absorption spectra are compared to further characterize AlQ3 and the hydrolysis pathway product, AlQ2OH. The activation energy for the cationic AlQ3 hydrolysis pathway is found to be 8.5 kcal mol(-1) lower than for the neutral reaction, which is significant since it suggests a role for charge imbalance in promoting chemical failure modes in OLED devices.

  12. Study on Mg/Al Weld Seam Based on Zn–Mg–Al Ternary Alloy

    Directory of Open Access Journals (Sweden)

    Liming Liu

    2014-02-01

    Full Text Available Based on the idea of alloying welding seams, a series of Zn–xAl filler metals was calculated and designed for joining Mg/Al dissimilar metals by gas tungsten arc (GTA welding. An infrared thermography system was used to measure the temperature of the welding pool during the welding process to investigate the solidification process. It was found that the mechanical properties of the welded joints were improved with the increasing of the Al content in the Zn–xAl filler metals, and when Zn–30Al was used as the filler metal, the ultimate tensile strength could reach a maximum of 120 MPa. The reason for the average tensile strength of the joint increasing was that the weak zone of the joint using Zn–30Al filler metal was generated primarily by α-Al instead of MgZn2. When Zn–40Al was used as the filler metal, a new transition zone, about 20 μm-wide, appeared in the edge of the fusion zone near the Mg base metal. Due to the transition zones consisting of MgZn2- and Al-based solid solution, the mechanical property of the joints was deteriorated.

  13. Optical, structural, and nuclear scientific studies of AlGaN with high Al composition

    Science.gov (United States)

    Lin, Tse Yang; Chung, Yee Ling; Li, Lin; Yao, Shude; Lee, Y. C.; Feng, Zhe Chuan; Ferguson, Ian T.; Lu, Weijie

    2010-08-01

    AlGaN epilayers with higher Al-compositions were grown by Metalorganic Chemical Vapor Deposition (MOCVD) on (0001) sapphire. Trimethylgallium (TMGa), trimethylaluminium (TMAl) and NH3 were used as the source precursors for Ga, Al, and N, respectively. A 25 nm AlN nucleation layer was first grown at low-temperature of 590 °C at 300 Torr. Followed, AlxGa1-xN layers were grown at 1080 °C on low-temperature AlN nucleation layers. The heterostructures were characterized by a series of techniques, including x-ray diffraction (XRD), Rutherford backscattering (RBS), photoluminescence (PL), scanning electron microscopy (SEM) and Raman scattering. Precise Al compositions were determined through XRD, RBS, and SEM combined measurements. Room Temperature Raman Scattering spectra shows three major bands from AlGaN alloys, which are AlN-like, A1 longitudinal optical (LO) phonon modes, and E2 transverse optical (TO) band, respectively, plus several peak comes from the substrate. Raman spectral line shape analysis lead to an optical determination of the electrical property free carrier concentration of AlGaN. The optical properties of AlGaN with high Al composition were presented here.

  14. Ion-beam mixing and thermal annealing of Al--Nb and Al--Ta thin films

    International Nuclear Information System (INIS)

    Rai, A.K.; Bhattacharya, R.S.; Mendiratta, M.G.; Subramanian, P.R.; Dimiduk, D.M.

    1988-01-01

    Ion-beam mixing and thermal annealing of thin, alternating layers of Al and Nb, as well as Al and Ta, were investigated by selected area diffraction and Rutherford backscattering. The individual layer thicknesses were adjusted to obtain the overall compositions as Al 3 Nb and Al 3 Ta. The films were ion mixed with 1 MeV Au + ions at a dose of 1 x 10 16 ions cm/sup -2/ . Uniform mixing and amorphization were achieved for both Al--Nb and Al--Ta systems. Equilibrium crystalline Al 3 Nb and Al 3 Ta phases were formed after annealing of ion mixed amorphous films at 400 0 C for 6 h. Unmixed films, however, remained unreacted at 400 0 C for 1 h. Partial reaction was observed in the unmixed film of Al--Nb at 400 0 C for 6 h. After annealing at 500 0 C for 1 h, a complete reaction and formation of Al 3 Nb and Al 3 Ta phases in the respective films were observed. The influence of thermodynamics on the phase formation by ion mixing and thermal annealing is discussed

  15. Effect of elevated Al and pH on the growth and root morphology of Al-tolerant and Al-sensitive wheat seedlings in an acid soil

    Directory of Open Access Journals (Sweden)

    Md. Toufiq Iqbal

    2014-03-01

    Full Text Available Aluminium ion (Al3+ toxicity and hydrogen ion (H+ activity are the major constraints for plant growth in acid soil. This study was undertaken to determine the effect of pH and Al on the growth response and changes in root morphology of Al-tolerant (ET8 and Al-sensitive (ES8 wheat seedlings. Different levels of AlCl3 and CaCO3 were added to the soils to manipulate soil pH and extractable Al. The results showed that the bulk soil pH remained constant at pH 4.1 with further applications of AlCl3, and that the seedlings died at the 200 mg AlCl3/kg treatments. The ET8 seedlings responded better than the ES8 seedlings in both low and high Al and pH. The ET8 seedlings had higher root surface areas and root tip numbers than the ES8 seedlings in the Al treatment. In contrast, the ES8 had higher root diameters than the ET8 seedlings due to the elevated Al supply. Apoplast Al increased with the increase of soil available extractable Al, and declined with the decrease of soil extractable Al. The ET8 seedlings accumulated more Al in their apoplast than the ES8 seedlings. This study concluded that accumulation of Al in the apoplast is also involved in Al tolerance mechanism with the addition of organic acid exudation.

  16. Information of “Nukhbat al-dahr fi ‘aja’ib al-barr wa-al-bahr” by ad-Dimashqi about the Turkic Tribes of Dasht-i Kipchak »

    Directory of Open Access Journals (Sweden)

    Z.S. Ilyasova

    2016-12-01

    Full Text Available This article introduced into academic circulation information of such a historical source as “Nukhbat al-dahr fi ‘aja’ib al-barr wa-al-bahr” (Excerpts of Time on the Marvels of the Land and Sea on Kipchak clans and Turkic tribes of Dasht-i Kipchak. The material of the study is drawn from this source. Main scientific result of this work was the source’s translation into Russian accompanied by scientific comments. Sheikh Shams al-Din Abu Abdallah Muhammad Abu Talib al-Ansari al-Sufi al-Dimashqi was the author of this work. Some scholars have mistakenly confuse him with another chronicler named Shihab al-Din Ahmad ibn Yahya Ibn Fadlallah al-Omari al-Dimashqi. There is a widespread misconception that while writing on Kipchak clans and Turkic tribes al-Dimashqi used the data of such an author as Muhammad ibn Ibrahim ibn Yahya al-Ansari al-Qutub al-Warraq al-Vatvat, also known as Ahmad al-Tini. After had studying the manuscripts of al-Tini and al-Dimashqi, we did not notice the connection between these two authors regarding their information about Kipchak clans and Turkic tribes of Dasht-i Kipchak. After had studying the information about Kipchak clans and Turkic tribes of Dasht-i Kipchak, we put forward the theory that 16 ethnonyms previously identified as Kipchak clans, are actually the etnonyms of eight Kipchak clans and eight Turkic tribes. The article also contains the extraction from “Nukhbat al-dahr fi ‘aja’ib al-barr wa-al-bahr” regarding the geography of Dasht-i Kipchak and the countries inhabited by the Turks. The following data are unique in this source: 1. The text describes such rivers as Ceyhun (Amu Darya, Seyhun (Syr Darya, Itil (Volga, as well as Khorezm and Khazar Seas (Aral and Caspian Seas. 2. Additionally, this text lists the following Turkic peoples: al-Kharlukhiya (Karluks, al-Khirgaziya (Kyrgyz, al-Kaymakiya (Kimaks, al-Guzziya (Oguz, al-Bazhanakiya (Pechenegs, al-Tuguzguziya (Uighurs, al-Khulkhiya (?, al

  17. Studies on SiC(p) reinforced Al-Al sub 3 Ni eutectic matrix composites

    International Nuclear Information System (INIS)

    Masrom, A.K.; Foo, L.C.; Ismail, A.B.

    1996-01-01

    An investigation on processing of Al-5.69wt% Ni eutectic with SiC particulate composites is reported. The intermetallic composites are prepared by elemental powder metallurgy route and sintered at two different temperatures, i.e., 600 degree C and 620 degree C. Results show that the metal matrix was Al-Al sub 3 Ni eutectic. The phase analysis by XRD identified the presence of Al sub 3 Ni and Al as dominant phases together with silicon and Al sub 4 C sub 3 phase as minor phases. The Al sub 4 C sub 3 and Si phases are formed during sintering due to SiC-Al interface reaction. SEM micrographs also reveal the formation of microvoid surrounding the SiC particle

  18. The constitution of alloys in the Al-rich corner of the Al-Si-Sm ternary system

    Energy Technology Data Exchange (ETDEWEB)

    Markoli, B.; Spaic, S. [Ljubljana Univ. (Slovenia). Faculty of Natural Science and Engineering; Zupanic, F. [Maribor Univ. (Slovenia). Faculty of Mechanical Engineering

    2001-09-01

    The constitution of alloys and the liquidus surface in the Al-rich corner of the Al-Si-Sm ternary system were determined by the examination of controlled heated and cooled specimens, as well as heat-treated specimens by means of optical and scanning electron microscopy, energy-dispersive X-ray spectroscopy, differential thermal analysis and X-ray diffraction. The Al-rich corner of the Al-Si-Sm ternary system comprises five regions of primary crystallisation ({alpha}{sub Al}, {beta}{sub Si}, Al{sub 3}Sm, Al{sub 2}Si{sub 2}Sm and AlSiSm) with following characteristic invariant reaction sequences: ternary eutectic reaction L {yields} {alpha}{sub Al} + {beta}{sub Si} + Al{sub 2}Si{sub 2}Sm, and two liquidus transition reactions, i. e., L + Al{sub 3}Sm {yields} {alpha}{sub Al} + AlSiSm, and L + AlSiSm {yields} {alpha}{sub Al} + Al{sub 2}Si{sub 2}Sm. Along with the position of ternary eutectic and both interstitial points in the Al-rich corner of the Al-Si-Sm ternary system, the temperatures for each reaction were determined. (orig.)

  19. Electronic Structures and Bonding Properties of Ti2AlC and Ti3AlC2

    Institute of Scientific and Technical Information of China (English)

    MIN Xinmin; REN Yi

    2007-01-01

    The relation among electronic structure, chemical bond and property of Ti2AlC, Ti3AlC2 and doping Si into Ti2AlC was studied by density function and the discrete variation (DFT-DVM) method. After adding Si into Ti2AlC, the interaction between Si and Ti is weaker than that between Al and Ti, and the strengths of ionic and covalent bonds decrease both. The ionic and covalent bonds in Ti3AlC2, especially in Ti-Al, are stronger than those in Ti2AlC. Therefore, in synthesis of Ti2AlC, the addition of Si enhances the Ti3AlC2 content instead of Ti2AlC. The density of state (DOS) shows that there is mixed conductor characteristic in Ti2AlC and Ti3AlC2. The DOS of Ti3AlC2 is much like that of Ti2AlC. Ti2SixAl1-x C has more obvious tendency to form a semiconductor than Ti2AlC, which is seen from the obvious difference of partial DOS between Si and Al3p.

  20. Caracterización del concentrado de cromita del yacimiento Merceditas, un criterio previo para la confección de mezclas termodifusivas

    Directory of Open Access Journals (Sweden)

    Carlo Díaz-Aguila

    2003-03-01

    Full Text Available Se caracteriza, desde el punto de vista fásico cuantitativo, el concentrado cromífero de características refractarias perteneciente al yacimiento Merceditas. Se emplearon técnicas de espectroscopía infrarroja y Mössbauer, de difractometría de rayos-X, análisis químico y granulométrico. Se establece que el concentrado se encuentra constituido por las fases mineralógicas cromopicotita, antigorita y clorita, y se determinan sus respectivas fórmulas cristaloquímicas. Mediante técnicas de análisis térmico (ATD, TG y TGD se estudia el comportamiento térmico de una mezcla de concentrado cromífero con aluminio, con vistas a valorar las posibilidades de los productos de la reducción como componentes de mezclas saturantes para la termodifusión superficial de cromo y silicio en aceros.

  1. Edificio Ince - Caracas (Venezuela

    Directory of Open Access Journals (Sweden)

    Sanabria, Tomás José

    1971-08-01

    Full Text Available This project includes a tall building, headquarters of the owning organisation, a four storey block, used for professional training purposes, and an auditorium. In addition there is underground space used as car park, and a small plaza with gardens, meant as an open air exhibition space for sculptures. The structure of the buildings is reinforced concrete, and the curtain walls are of anodizod aluminium.El conjunto comprende: el edificio torre, sede de la Institución; un bloque de cuatro plantas, destinado para centro de formación profesional, y un auditorio. Hay, además, un sótano, que alberga: el estacionamiento de vehículos y zonas de instalaciones diversas, y una plaza tratada paisajísticamente y destinada a exposición permanente de escultura al aire libre. Su estructura es de hormigón armado y los cerramientos son de aluminio anodizado.

  2. Centro médico de rehabilitación, en Viena – Austria

    Directory of Open Access Journals (Sweden)

    Piechl, G.

    1971-03-01

    Full Text Available This medical building, which is new in its type in Austria, is at Meidling, close to the largest hospital devoted to accidents in Austria. It is star shaped, in horizontal platform, with three branches, and has three floor levels. It can houses 50 patients. Construction is concrete cast in situ and precast units. External windows are aluminium framed, and all the fittings are of very high quality.Este edificio sanitario —nuevo en su género en Austria— está situado en Meidling, próximo al mayor centro médico para accidentes de trabajo del país. Tiene planta en estrella con tres brazos y tres plantas de altura, y capacidad para 50 pacientes. La construcción es mixta: hormigón vertido in situ y elementos prefabricados; carpintería exterior de aluminio y dotación de gran lujo de instalaciones.

  3. Pornographie als Metapher

    Directory of Open Access Journals (Sweden)

    Caroline Schubarth

    2010-02-01

    Full Text Available In diesem Artikel werden unterschiedliche metaphorische Verwendungen des Pornografiebegriffs und deren Implikationen untersucht. Während die Existenz von Pornografie der feministischen Anti-Porno-Bewegung als Erklärung für die anhaltende Diskriminierung von Frauen in westlichen Gesellschaften dient, nutzen rechtskonservative Kräfte den Pornografievorwurf als Rechtfertigung für die Zensur von als deviant empfundenen Identitäten und sexuellen Praktiken.

  4. Estudio fraccional densométrico de la mena laterítica: evaluación del enriquecimiento

    Directory of Open Access Journals (Sweden)

    Alberto Hernández-Flores

    2017-07-01

    Full Text Available Se realizó el análisis fraccional al intervalo granulométrico -2,0+0,074mm de una muestra del yacimiento Punta Gorda, atendiendo a las propiedades físicas de diámetro y densidad de las partículas. Mediante la combinación del análisis de cribado y de la separación de las fracciones de densidad con el empleo de diferentes medios densos se obtiene la función bidimensional de distribución, por el grosor o diámetro y por la densidad, y a través del análisis químico se determina la función experimental. Se realiza la evaluación del beneficio con el empleo del modelo Teoría de separación y se obtienen los parámetros tecnológicos. Como resultado fundamental se logra un concentrado con la separación de la mayor cantidad del magnesio y aluminio de 94,89% y 91,15%, respectivamente. Esto permite pronosticar un mejoramiento en la calidad y estabilidad de la mena de alimentación al proceso extractivo y diversificar el uso del recursos.

  5. Deletion of ALS5, ALS6 or ALS7 increases adhesion of Candida albicans to human vascular endothelial and buccal epithelial cells

    OpenAIRE

    ZHAO, XIAOMIN; OH, SOON-HWAN; HOYER, LOIS L.

    2007-01-01

    C. albicans yeast forms deleted for ALS5, ALS6 or ALS7 are more adherent than a relevant control strain to human vascular endothelial cell monolayers and buccal epithelial cells. In the buccal and vaginal reconstituted human epithelium (RHE) disease models, however, mutant and control strains caused a similar degree of tissue destruction. Deletion of ALS5 or ALS6 significantly slowed growth of the mutant strain; this phenotype was not affected by addition of excess uridine to the culture medi...

  6. Alpha and beta stabilizer character of Al in Zr-Nb-Al alloys

    International Nuclear Information System (INIS)

    Peruzzi Bardella, A.; Bolcich, J.C.

    1987-01-01

    The T β/α+β of Zr5Nb and Zr5Nb2Al (weight %) were determined in order to observe the alpha-stabilizer character of Al in ternary Zr-Nb-Al alloys. Techniques employed were change of resistivity with temperature in dynamic experiences, and metallography of samples quenched to room temperature after isothermal annealings. The T β/α+β of the ternary resulted 17 ± 8 deg C higher than that of the binary alloy. In addition, taking into account the results of previous investigations of the transformation of beta on quenching Zr-Nb-Al alloys from the beta field to room temperature, it is concluded that the beta-stabilizer character of Nb is stronger than the alpha-stabilizer character of Al in these Zr alloys, and that the Al can have important influence on the mechanical properties by the appearance of TRIP effect. (Author) [es

  7. Insulator-semiconductor interface fixed charges in AlGaN/GaN metal-insulator-semiconductor devices with Al2O3 or AlTiO gate dielectrics

    Science.gov (United States)

    Le, Son Phuong; Nguyen, Duong Dai; Suzuki, Toshi-kazu

    2018-01-01

    We have investigated insulator-semiconductor interface fixed charges in AlGaN/GaN metal-insulator-semiconductor (MIS) devices with Al2O3 or AlTiO (an alloy of Al2O3 and TiO2) gate dielectrics obtained by atomic layer deposition on AlGaN. Analyzing insulator-thickness dependences of threshold voltages for the MIS devices, we evaluated positive interface fixed charges, whose density at the AlTiO/AlGaN interface is significantly lower than that at the Al2O3/AlGaN interface. This and a higher dielectric constant of AlTiO lead to rather shallower threshold voltages for the AlTiO gate dielectric than for Al2O3. The lower interface fixed charge density also leads to the fact that the two-dimensional electron concentration is a decreasing function of the insulator thickness for AlTiO, whereas being an increasing function for Al2O3. Moreover, we discuss the relationship between the interface fixed charges and interface states. From the conductance method, it is shown that the interface state densities are very similar at the Al2O3/AlGaN and AlTiO/AlGaN interfaces. Therefore, we consider that the lower AlTiO/AlGaN interface fixed charge density is not owing to electrons trapped at deep interface states compensating the positive fixed charges and can be attributed to a lower density of oxygen-related interface donors.

  8. Effects of Al(III and Nano-Al13 Species on Malate Dehydrogenase Activity

    Directory of Open Access Journals (Sweden)

    Rong Fu Chen

    2011-05-01

    Full Text Available The effects of different aluminum species on malate dehydrogenase (MDH activity were investigated by monitoring amperometric i-t curves for the oxidation of NADH at low overpotential using a functionalized multi-wall nanotube (MWNT modified glass carbon electrode (GCE. The results showed that Al(III and Al13 can activate the enzymatic activity of MDH, and the activation reaches maximum levels as the Al(III and Al13 concentration increase. Our study also found that the effects of Al(III and Al13 on the activity of MDH depended on the pH value and aluminum speciation. Electrochemical and circular dichroism spectra methods were applied to study the effects of nano-sized aluminum compounds on biomolecules.

  9. Effects of Al(III) and nano-Al13 species on malate dehydrogenase activity.

    Science.gov (United States)

    Yang, Xiaodi; Cai, Ling; Peng, Yu; Li, Huihui; Chen, Rong Fu; Shen, Ren Fang

    2011-01-01

    The effects of different aluminum species on malate dehydrogenase (MDH) activity were investigated by monitoring amperometric i-t curves for the oxidation of NADH at low overpotential using a functionalized multi-wall nanotube (MWNT) modified glass carbon electrode (GCE). The results showed that Al(III) and Al(13) can activate the enzymatic activity of MDH, and the activation reaches maximum levels as the Al(III) and Al(13) concentration increase. Our study also found that the effects of Al(III) and Al(13) on the activity of MDH depended on the pH value and aluminum speciation. Electrochemical and circular dichroism spectra methods were applied to study the effects of nano-sized aluminum compounds on biomolecules.

  10. Fracture toughness of Ti-Al3Ti-Al-Al3Ti laminate composites under static and cyclic loading conditions

    Science.gov (United States)

    Patselov, A. M.; Gladkovskii, S. V.; Lavrikov, R. D.; Kamantsev, I. S.

    2015-10-01

    The static and cyclic fracture toughnesses of a Ti-Al3Ti-Al-Al3Ti laminate composite material containing at most 15 vol % intermetallic compound are studied. Composite specimens are prepared by terminating reaction sintering of titanium and aluminum foils under pressure. The fracture of the titanium layers is quasi-cleavage during cyclic crack growth and is ductile during subsequent static loading.

  11. Data supporting Al-Abed et al., Environ. Sci.: Nano, 2016,

    Data.gov (United States)

    U.S. Environmental Protection Agency — Data files representing each of the Figures and Tables published in Al-Abed et al., Environ. Sci.: Nano, 2016, 3, 593. The data file names identify the Figure or...

  12. Ti, Al

    Indian Academy of Sciences (India)

    In the present study, authors report on the effect that substrate bias voltage has on the microstructure and mechanical properties of (Ti, Al)N hard coatings deposited with cathodic arc evaporation (CAE) technique. The coatings were deposited from a Ti0.5Al0.5 powder metallurgical target in a reactive nitrogen atmosphere at ...

  13. Growth of CdTe: Al films; Crecimiento de peliculas de CdTe: Al

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez A, M.; Zapata T, M. [CICATA-IPN, 89600 Altamira, Tamaulipas (Mexico); Melendez L, M. [CINVESTAV-IPN, A.P. 14-740, 07000 Mexico D.F. (Mexico); Pena, J.L. [CINVESTAV-IPN, A.P. 73 Cordemex, 97310 Merida, Yucatan (Mexico)

    2006-07-01

    CdTe: AI films were grown by the close space vapor transport technique combined with free evaporation (CSVT-FE). The Aluminum (Al) evaporation was made by two kinds of sources: one made of graphite and the other of tantalum. The films were deposited on glass substrates. The Al source temperature was varied maintaining the CdTe source temperature fixed as well as the substrate temperature. The films were characterized by x-ray energy dispersive analysis (EDAX), x-ray diffraction and optical transmission. The results showed for the films grown with the graphite source for Al evaporation, the Al did not incorporate in the CdTe matrix, at least to the level of EDAX sensitivity; they maintained the same crystal structure and band gap. For the samples grown with the tantalum source, we were able to incorporate the Al. The x-ray diffraction patterns show that the films have a crystal structure that depends on Al concentration. They were cubic up to 2.16 at. % Al concentration; for 19.65 at. % we found a mixed phase; for Al concentration higher than 21 at. % the films were amorphous. For samples with cubic structure it was found that the lattice parameter decreases and the band gap increases with Al concentration. (Author)

  14. First-principles study of L10 Ti-Al and V-Al alloys

    International Nuclear Information System (INIS)

    Chubb, S.R.; Papaconstantopoulos, D.A.; Klein, B.M.

    1988-01-01

    As a first step towards understanding the reduced embrittlement of L1 0 Ti-Al alloys which accompanies the introduction of small concentrations of V, we have determined from first principles, using full-potential linearized--augmented-plane-wave calculations, the equilibrium values of the structural parameters and the associated electronic structure for the stoichiometric (L1 0 ) Ti-Al (tetragonal) compound. Our calculated values of c/a and a are in good agreement with experiment. Using the same method of calculation, we have also studied the electronic structure associated with the (hypothetical) L1 0 V-Al alloy that would form when V is substituted for Ti. We find that (1) the electronic structures of these V-Al alloys are relatively insensitive to variations of c/a and a; (2) near the Ti-Al equilibrium geometry, the electronic structures of the V-Al and Ti-Al alloys are very similar; and (3) that a rigid-band model involving substitution of V for Ti can be used to gain a qualitative understanding of the reduction in c/a which accompanies the introduction of small concentrations of V. We relate the reduction in c/a to important changes in the bonding that accompany the occupation of bands immediately above the Fermi level of the stoichiometric Ti-Al compound

  15. Kinetic studies of oxidation of MgAlON and a comparison of the oxidation behaviour of AlON, MgAlON, O'SiAlON-ZrO{sub 2}, and BN-ZCM ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Wang Xidong; Seetharaman, S. [Div. of Metallurgy, Royal Inst. of Tech., Stockholm (Sweden); Li Wenchao [Dept. of Physical Chemistry, Univ. of Science and Technology Beijing (USTB), Beijing, BJ (China)

    2002-06-01

    The kinetics and morphology of the oxidation process of magnesium-aluminium oxynitride (MgAlON), aluminium oxynitride (AlON), O'SiAlON-ZrO{sub 2}, and BN-ZCM have been studied in the temperature range 1373-1773 K (ZCM=30 wt% ZrO{sub 2}, 52 wt% Al{sub 2}O{sub 3} and 18 wt% 3 Al{sub 2}O{sub 3}.2 SiO{sub 2}). Oxidation experiments with powder and plate samples of the above materials have been carried out in air. MgAlON shows the best resistance to oxidation at lower temperatures (< 1473 K), whereas at higher temperatures ({proportional_to} 773 K), AlON shows the best resistance. O'SiAlON-ZrO{sub 2} shows very good oxidation resistance up to 1673 K. But its oxidation rate increases strongly above 1673 K, presumably due to the formation of liquid phase. BN-ZCM has the poorest oxidation resistance due to the evaporation of B{sub 2}O{sub 3}. The activation energies for the chemical oxidation reaction of AlON, MgAlON, and O'SiAlON-ZrO{sub 2} are 214, 330 and 260 kJ/mol, respectively. The overall diffusion activation energies for AlON, MgAlON, O'SiAlON-ZrO{sub 2} and BN-ZCM are 227, 573, 367 and 289 kJ/mol, respectively. (orig.)

  16. Grain refining mechanism of Al-containing Mg alloys with the addition of Mn-Al alloys

    International Nuclear Information System (INIS)

    Qin, Gaowu W.; Ren Yuping; Huang Wei; Li Song; Pei Wenli

    2010-01-01

    Graphical abstract: Display Omitted Research highlights: The ε-AlMn phase acts as the heterogeneous nucleus of α-Mg phase during the solidification of the AZ31 Mg alloy, not the γ-Al 8 Mn 5 phase. The grain refinement effect is very clear with the addition of only 0.5 wt% Mn-28Al alloy (pure ε-AlMn). The grain refinement does not deteriorate up to the holding time of 60 min at 740 o C. - Abstract: The effect of manganese on grain refinement of Al-containing AZ31 Mg alloy has been investigated by designing a series of Mn-Al alloys composed of either pure ε-AlMn, γ 2 -Al 8 Mn 5 or both of them using optical microscopy and X-ray diffraction. It is experimentally clarified that the grain refinement of the AZ31 Mg alloy is due to the existence of the ε-AlMn phase in the Mn-Al alloys, not the γ 2 -Al 8 Mn 5 phase. The grain size of AZ31 Mg alloy is about 91 μm without any addition of Mn-Al alloys, but remarkably decreases to ∼55 μm with the addition of either Mn-34 wt% Al or Mn-28 wt% Al. With a minor addition of 0.5 wt% Mn-28Al alloy, the grain size of AZ31 alloy decreases to ∼53 μm, and the Mn-28Al alloy can be active as grain refiner for holding time up to 60 min for the melt AZ31 alloy at 750 o C.

  17. Ibn Qutayba en al-Andalus. La préface à I 'Adab al-Kātib dans le commentaire d'Ibn al-Sīd al-Baṭalyawsī

    Directory of Open Access Journals (Sweden)

    Soravia, Bruna

    2004-12-01

    Full Text Available Ibn Qutayba's preface to his Adab al-kātib has been considered for centuries the most important section of this work and it has been the object of many commentaries, both in the Muslim East and West. This paper deals with Ibn al-Sīd al-Baṭalyawsī´s commentary al-Iqtiḍāb, trying to show the peculiar way in which Ibn al-Sīd develops his own critique of Ibn Qutayba's controversial thesis on the relation between orthodoxy, falsafa and kalām. At the same time, the Andalusi author works out his own conception of adab, deeply influenced by his biographical experience. Finally a full translation of Ibn Qutayba's preface is proposed, half a century after G. Lecomte's partial one.

    El prefacio de Ibn Qutayba a su Adab al-Kātib ha sido considerado durante siglos como el fragmento más importante de su obra, y ha sido objeto de muchos comentarios, tanto orientales como occidentales. Este artículo trata del comentario que Ibn al-Sīd al-Baṭalyawsī hizo de ese texto de Ibn Qutayba, e intenta mostrar la forma peculiar en que Ibn al-Sīd desarrolla su propia crítica a la polémica tesis de Ibn Qutayba sobre la relación entre ortodoxia, falsafa y kalām. Al mismo tiempo, el autor andalusí elabora su propia concepción del adab, profundamente influida por su experiencia biográfica. Para concluir, se presenta una traducción completa del prefacio de Ibn Qutayba, medio siglo después de la parcial realizada por G. Lecomte.

  18. Interview als Text vs. Interview als Interaktion

    Directory of Open Access Journals (Sweden)

    Arnulf Deppermann

    2013-09-01

    Full Text Available Das Interview ist nach wie vor das beliebteste sozialwissenschaftliche Verfahren des Datengewinns. Ökonomie der Erhebung, Vergleichbarkeit und die Möglichkeit, Einsicht in Praxisbereiche und historisch-biografische Dimensionen zu erhalten, die der direkten Beobachtung kaum zugänglich sind, machen seine Attraktivität aus. Zugleich mehren sich Kritiken, die seine Leistungsfähigkeit problematisieren, indem sie auf die begrenzte Reichweite der Explikationsfähigkeiten der Befragten, die Reaktivität der Erhebung oder die Differenz zwischen Handeln und dem Bericht über Handeln verweisen. Im Beitrag wird zwischen Ansätzen, die das Interview als Text, und solchen, die es als Interaktion verstehen, unterschieden. Nach dem Text-Verständnis werden Interviews unter inhaltlichen Gesichtspunkten analysiert und als Zugang zu einer vorgängigen sozialen oder psychischen Wirklichkeit angesehen. Das Interaktions-Verständnis versteht Interviews dagegen als situierte Praxis, in welcher im Hier und Jetzt von InterviewerInnen und Befragten gemeinsam soziale Sinnstrukturen hergestellt werden. Anhand ubiquitärer Phänomene der Interviewinteraktion – Fragen, Antworten und die Selbstpositionierung von InterviewerInnen und Befragten – werden Praktiken des interaktiv-performativen Handelns im Interview dargestellt. Ihre Relevanz für die Interviewkonstitution und ihre Erkenntnispotenziale für die Interviewauswertung werden aufgezeigt. Es wird dafür plädiert, die interaktive Konstitutionsweise von Interviews empirisch zu erforschen und methodisch konsequent zu berücksichtigen. URN: http://nbn-resolving.de/urn:nbn:de:0114-fqs1303131

  19. Structure and phase composition of Al-Ce-Cu system alloys in range of quasi-binary Al-Al8CeCu4 section

    International Nuclear Information System (INIS)

    Belov, N.A.; Khvan, A.V.

    2007-01-01

    The phase diagram of the Al-Cu-Ce system in the quasibinary section area of Al-Al 8 CeCu 4 has been investigated by metallographic, thermal, micro-X-ray spectral and X-ray structural analyses. The parameters of the eutectic reaction L→(Al)+CeCu 4 Al 8 : T=610 Deg C were found out; the composition was 14% Cu and 7% Ce. This eutectics is of a disperse structure and the ternary compound contained is capable of fragmentation and spheroidizing in the heating process (starting from 540 Deg C). It was demonstrated that the area of optimal (Al)+CeCu 4 Al 8 eutectics-based alloy compositions was within the narrow limits. That is related to the fact that at a comparatively little variation of the Cu:Ce=2 ratio solidus sharply decreases and, as a result, the crystallization interval considerably extends [ru

  20. Observaciones microestructurales en el composite Al-SiC-15p obtenido por el procedimiento de compocolado

    Directory of Open Access Journals (Sweden)

    Manzano-Ramírez, A.

    1996-12-01

    Full Text Available In order to study how the processing variables of the compocasting process, such as shear rate and solid fraction, influence the mechanical entrapment of SiCp in the aluminium matrix of the Al-SiC-xxp composite. In the present work, shear rate and solid fraction were varied (γ = 27, 120 and 219 s-1 and fs = 0.3, 0.4 and 0.5, respectively. In addition, the atomic force microscope (AFM was used to investigate the surface topography of the composite, with the purpose of determine, qualitatively, the degree of interfacial bonding between aluminium matrix and reinforcement elements. By using the Chemical facilities of SEM it was attempted to determine the composition of the second phase responsible of bonding between matrix and particulate. The results obtained in the AFM confirmed that the mechanical entrapment of the particles by the solid is more efficient at high solid fractions (fs > 0.4 and high shear rates (γ > 120 s-1. In contrast, at low fs (< 0.3 and low γ (< 27 s-1 such effect is poor. In addition, qualitative evidence, recorded by optical micrographs, illustrate the mechanism of dendritic fragmentation and change (from dendritic to globular of the primary-solid phase in the compocasting process. SEM results suggested that bonding could be established through the silicon phase nevertheless it is considered that more accurate analysis is needed.

    El propósito del presente trabajo es estudiar el efecto de las variables del procedimiento de compocolado (compocasting, velocidad de agitación y fracción de sólido, sobre el atrapamiento mecánico o incorporación de partículas de SiC a la matriz de aluminio del composite Al-SiC-15p. Para ello, se variaron la velocidad de corte, γ, y la fracción de sólido fs, (γ= 27, 120 y 213 s-1 y fs = 0,3, 0,4 y 0,5, respectivamente. Se utilizó el microscopio de fuerza atómica (AFM para observar la topografía del

  1. Structural and electrical characterization of AuPtAlTi ohmic contacts to AlGaN/GaN with varying annealing temperature and Al content

    OpenAIRE

    Fay, Mike W.; Han, Y.; Brown, Paul D.; Harrison, Ian; Hilton, K.P.; Munday, A.; Wallis, D.; Balmer, R.S.; Uren, M.J.; Martin, T.

    2008-01-01

    The effect of varying annealing temperature and Al layer thickness on the structural and electrical characteristics of AuPtAlTi/AlGaN/GaN ohmic contact structures has been systematically investigated. The relationship between annealing temperature, Al content, interfacial microstructure, surface planarity and contact resistance is\\ud examined. In particular, the presence of a detrimental low temperature Pt-Al reaction is identified. This is implicated in both the requirement for a higher Al:T...

  2. Grain refining mechanism of Al-containing Mg alloys with the addition of Mn-Al alloys

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Gaowu W., E-mail: qingw@smm.neu.edu.c [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Wenhu Road 3-11, Heping District, Shenyang 110004, Liaoning Province (China); Ren Yuping; Huang Wei; Li Song; Pei Wenli [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Wenhu Road 3-11, Heping District, Shenyang 110004, Liaoning Province (China)

    2010-10-08

    Graphical abstract: Display Omitted Research highlights: The {epsilon}-AlMn phase acts as the heterogeneous nucleus of {alpha}-Mg phase during the solidification of the AZ31 Mg alloy, not the {gamma}-Al{sub 8}Mn{sub 5} phase. The grain refinement effect is very clear with the addition of only 0.5 wt% Mn-28Al alloy (pure {epsilon}-AlMn). The grain refinement does not deteriorate up to the holding time of 60 min at 740 {sup o}C. - Abstract: The effect of manganese on grain refinement of Al-containing AZ31 Mg alloy has been investigated by designing a series of Mn-Al alloys composed of either pure {epsilon}-AlMn, {gamma}{sub 2}-Al{sub 8}Mn{sub 5} or both of them using optical microscopy and X-ray diffraction. It is experimentally clarified that the grain refinement of the AZ31 Mg alloy is due to the existence of the {epsilon}-AlMn phase in the Mn-Al alloys, not the {gamma}{sub 2}-Al{sub 8}Mn{sub 5} phase. The grain size of AZ31 Mg alloy is about 91 {mu}m without any addition of Mn-Al alloys, but remarkably decreases to {approx}55 {mu}m with the addition of either Mn-34 wt% Al or Mn-28 wt% Al. With a minor addition of 0.5 wt% Mn-28Al alloy, the grain size of AZ31 alloy decreases to {approx}53 {mu}m, and the Mn-28Al alloy can be active as grain refiner for holding time up to 60 min for the melt AZ31 alloy at 750 {sup o}C.

  3. AYAT-AYAT WAH}DAT AL-WUJUd dalam Kitab Tanbi>h al-Ma>shi Karya ‘Abdurrauf al-Sinkili

    Directory of Open Access Journals (Sweden)

    Asep Nahrul Musadad

    2015-08-01

    Full Text Available Abstract: One of the key moments in discussing the history of Indonesian Islam is a polemic related to the negotiation on the doctrine of wahdat al-wujud that occured in Aceh in 17th century between the followers of Hamzah al-Fansuri and Nuruddin al-Raniri. This article focuses on analyzing several Qur’anic verses used by ‘Abdurrauf as the confirmation of his argument. In the polemical context, Abdurrauf al-Sinkili appeared to be an actor of reconciliation between two opposite sides. He tried to respond to the disputed issues through his book called “Tanbi>h al-Mashi”. As an exponent of the so-called moderate sufism (mysticism, he built the argument concerning wah}dat al-wujud based on the Quranic text. After making a thematic classification chronologically, his interpretation on these verses is analyzed by using Hussain al-Dhahaby’s theory of sufistic exegesis. In conclusion, it shows that ‘Abdurrauf’s commentary is “sufi-nazari type”, featured by his exegeses pattern. This, of course, represents his attitude as a reconciler who then needs to seek confirmation to the Qur’anic verses in evaluating wah}dat al-wujud doctrine, through which such a polemical issues occurred at that time. الملخص: إن من المرحلة الأساسية التي مرّ بها تاريخ الإسلام في اندونيسيا الجدل و النزاع حول عقيدة وحدة الوجود فى أتشيه (Aceh حول قرن السابع عشر بين أتباع حمزة الفنسوري و نور الدين الرانيري. ففي ذلك الخطاب النزاعي جاء عبد الرؤوف السنكيلي مصلحا بين الجانبين المعاكسين. وعلى مقتضى الظروف، كتب كتاب " تنبيه الماشي" الذي تطرّق فيه طريق التوسّط، ممثّلا للتصوّف المعتدل. اعتمد عبد الرؤوف على النصوص القرآنية فى تحقيق آراءه حول ت

  4. Reviewing Medical Education in KamelAl-Senaat Al-Tebieh

    Directory of Open Access Journals (Sweden)

    Shahla Moradi

    2017-06-01

    Full Text Available Background and Objective: Among the human sciences, medicine is superior to all other sciences. One of the effective factors in education, especially in medical education is using appropriate textbooks. This study aims to consider a classic book of medical education and find its relevance to modern medicine. Materials and Methods: Reviewing and analyzing parts of Kamel Al-Senaat Al-Tebieh medical textbook. Results: This book has about four hundred thousand words and it was divided into twenty articles, each consisting of several chapters, first ten topics of which are about theoretical medicine, and others are information related to practical medicine. Conclusion: One of the most important obligations of every nation is to protect and preserve written and unwritten cultural and scientific resources Kamel Al-Senaat Al-Tebieh was written in one of the glorious periods of Iranian Medical History by Ali Ibn Abbas. It has a dignified position because of its recording method. This method is one of the best methods that is used after Ahvazi. Even today it is a valuable source of medical education.

  5. Density and atomic volume in liquid Al-Fe and Al-Ni binary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Plevachuk, Yu. [Ivan Franko National Univ., Lviv (Ukraine). Dept. of Metal Physics; Egry, I.; Brillo, J.; Holland-Moritz, D. [Deutsches Zentrum fuer Luft- und Raumfahrt, Koeln (Germany). Inst. fuer Raumsimulation; Kaban, I. [Chemnitz Univ. of Technolgy (Germany). Inst. of Physics

    2007-02-15

    The density of liquid Al-Fe and Al-Ni binary alloys have been determined over a wide temperature range by a noncontact technique combining electromagnetic levitation and optical dilatometry. The temperature and composition dependences of the density are analysed. A negative excess volume correlates with the negative enthalpy of mixing, compound forming ability and chemical short-range ordering in liquid Al-Fe and Al-Ni alloys. (orig.)

  6. TEM characterization of Al-C-Cu-Al2O3 composites produced by mechanical milling

    International Nuclear Information System (INIS)

    Santos-Beltran, A.; Gallegos-Orozco, V.; Estrada-Guel, I.; Bejar-Gomez, L.; Espinosa-Magana, F.; Miki-Yoshida, M.; Martinez-Sanchez, R.

    2007-01-01

    Novel Al-based composites (Al-C-Cu-Al 2 O 3 ) obtained by mechanical milling (MM), were characterized by transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS). Analyses of composites were carried out in both, the as-milled and the as-sintered conditions. C nanoparticles were found in the as-milled condition and Al 2 O 3 nanofibers were found in as-sintered products, as determined by EELS. C and Cu react with Al to crystallize in Al 3 C 4 and Al 2 Cu structures, respectively

  7. Formation of AlFeSi phase in AlSi12 alloy with Ce addition

    Directory of Open Access Journals (Sweden)

    S. Kores

    2012-04-01

    Full Text Available The influence of cerium addition on the solidification sequence and microstructure constituents of the Al-Si alloys with 12,6 mass % Si was examined. The solidification was analyzed by a simple thermal analysis. The microstructures were examined with conventional light and scanning electron microscopy. Ternary AlSiCe phase was formed in the Al-Si alloys with added cerium during the solidification process. AlSiCe and β-AlFeSi phases solidified together in the region that solidified the last. Cerium addition influenced on the morphology of the α-AlFeSi phase solidification.

  8. Compressive performance and crack propagation in Al alloy/Ti{sub 2}AlC composites

    Energy Technology Data Exchange (ETDEWEB)

    Hanaor, D.A.H., E-mail: dorian.hanaor@sydney.edu.au [School of Civil Engineering, University of Sydney, Sydney, NSW 2006 (Australia); Hu, L. [Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011 (United States); Kan, W.H.; Proust, G. [School of Civil Engineering, University of Sydney, Sydney, NSW 2006 (Australia); Foley, M. [Australian Centre for Microscopy and Microanalysis, University of Sydney, Sydney, NSW 2006 (Australia); Karaman, I.; Radovic, M. [Department of Materials Science and Engineering, Texas A& M University, College Station, TX 77843 (United States)

    2016-08-30

    Composite materials comprising a porous Ti{sub 2}AlC matrix and Al 6061 alloy were fabricated by a current-activated pressure assisted melt infiltration process. Coarse, medium and fine meso-structures were prepared with Al alloy filled pores of differing sizes. Materials were subjected to uniaxial compressive loading up to stresses of 668 MPa, leading to the failure of specimens through crack propagation in both phases. As-fabricated and post-failure specimens were analysed by X-ray microscopy and electron microscopy. Quasi-static mechanical testing results revealed that compressive strength was the highest in the fine structured composite materials. While the coarse structured specimens exhibited a compressive strength of 80% relative to this. Reconstructed micro-scale X-ray tomography data revealed different crack propagation mechanisms. Large planar shear cracks propagated throughout the fine structured materials while the coarser specimens exhibited networks of branching cracks propagating preferentially along Al alloy-Ti{sub 2}AlC phase interfaces and through shrinkage pores in the Al alloy phase. Results suggest that control of porosity, compensation for Al alloy shrinkage and enhancement of the Al alloy-Ti{sub 2}AlC phase interfaces are key considerations in the design of high performance metal/Ti{sub 2}AlC phase composites.

  9. Phase equilibria and crystalline structure of compounds in the Lu-Al and Lu-Cu-Al systems

    International Nuclear Information System (INIS)

    Kuz'ma, Yu.B.; Stel'makhovich, B.M.; Galamushka, L.I.

    1992-01-01

    Phase equilibria and crystal structure of compounds in Lu-Al and Lu-Cu-Al systems were studied. Existence of Lu 2 Al compound having the structure of the PbCl 2 type is ascertained. Diagram of phase equilibria of Lu-Cu-Al system at 870 K is plotted. Compounds Lu 2 (Cu,Al) 17 (the Th 2 Zn 17 type structure), Lu(Cu,Al) 5 (CaCu 5 type structure), Lu 6 (Cu,Al) 23 (Th 6 Mn 23 type structure) and ∼ LuCuAl 2 have been prepared for the first time. Investigation of component interaction in Lu-Cu-Al system shows that the system is similar to previously studied systems Dy-Cu-Al and Er-Cu-Al. The main difference consists in the absence of LuCuAl 3 compound with rhombic structure of the CeNi 2+x Sb 2-x type in the system investigated

  10. Tribology of ZRN, CRN and TIALN thin films deposited by reactive magnetron sputtering

    Directory of Open Access Journals (Sweden)

    Alexander Ruden

    2013-01-01

    Full Text Available El coeficiente de fricción y el coeficiente de desgaste, representan dos variables importantes para la elección de recubrimientos duros en aplicaciones críticas de ingeniería tales como corte y conformado de materiales. Para explicar de manera profunda estas variables, es necesario conocer los diferentes tipos de desgaste que ocurren en estas superficies recubiertas. Se han evaluado recubrimientos de nitruro de circonio (ZrN, nitruro de cromo (CrN y nitruro de titanio aluminio (TiAlN, producidos por la técnica magnetrón sputtering reactivo, determinando las propiedades tribológicas, midiendo coeficientes de fricción (COF y desgaste, y mostrando un análisis de los mecanismos de desgaste presentes para cada recubrimiento durante el contacto tribológico en sistemas cerámicos. Se observó que el voltaje de polarización incrementa las fallas por deformación plástica y la generación de un tercer cuerpo en la superficie del ZrN. El aumento del flujo de nitrógeno en la deposición de CrN, mejora el comportamiento tribológico al segregar la fase cúbica del material, optimizando sus propiedades superficiales. Al incrementar la temperatura de deposición del TiAlN se mejora su calidad superficial (reducción de rugosidad y densidad de poros, reduciendo la abrasión y aumentando la capacidad de carga del compuesto.

  11. Al Qaeda in the Arabian Peninsula (AQAP): An Al Qaeda Affiliate Case Study

    Science.gov (United States)

    2017-10-01

    Villarosa, Al-Qaeda in Yemen, Carnegie Endowment, July 7, 2009, http://carnegieendowment.org/2009/07/07/Al-Qaeda-in-yemen- event-1372. 53 Brian Whitaker...73 Khaled Fattah, “Yemen’s Insecurity Dilemma,” Yemen Times, February 11, 2014, http:// carnegie -mec.org/2014/02...Johnsen, and Shari Villarosa, “Al-Qaeda in Yemen.” Carnegie Endowment. July 7, 2009. http://carnegieendowment.org/2009/07/07/Al-Qaeda-in- yemen-event

  12. Formation of epitaxial Al 2O 3/NiAl(1 1 0) films: aluminium deposition

    Science.gov (United States)

    Lykhach, Y.; Moroz, V.; Yoshitake, M.

    2005-02-01

    Structure of epitaxial Al 2O 3 layers formed on NiAl(1 1 0) substrates has been studied by means of reflection high-energy electron diffraction (RHEED). The elucidated structure was compared to the model suggested for 0.5 nm-thick Al 2O 3 layers [K. Müller, H. Lindner, D.M. Zehner, G. Ownby, Verh. Dtsch. Phys. Ges. 25 (1990) 1130; R.M. Jaeger, H. Kuhlenbeck, H.J. Freund, Surf. Sci. 259 (1991) 235]. The stepwise growth of Al 2O 3 film, involving deposition and subsequent oxidation of aluminium onto epitaxial 0.5 nm-thick Al 2O 3 layers, has been investigated. Aluminium was deposited at room temperature, whereas its oxidation took place during annealing at 1070 K. The Al 2O 3 thickness was monitored by means of Auger electron spectroscopy (AES). It was found that Al 2O 3 layer follows the structure of 0.5 nm thick Al 2O 3 film, although a tilting of Al 2O 3(1 1 1) surface plane with respect to NiAl(1 1 0) surface appeared after Al deposition.

  13. Amyotrophic lateral sclerosis (ALS)

    Science.gov (United States)

    Lou Gehrig disease; ALS; Upper and lower motor neuron disease; Motor neuron disease ... One out of 10 cases of ALS is due to a genetic defect. The cause is unknown in most other cases. In ALS, motor nerve cells (neurons) waste away ...

  14. Pemikiran Politik al-Shawkânî dalam Fath al-Qadîr

    Directory of Open Access Journals (Sweden)

    Yusuf Hanafi

    2015-09-01

    Full Text Available Muhammad b. ‘Alî Muhammad b. ‘Abd Allâh al-Shawkânî al-San‘ânî. He was born in the Hijrah in Shawkân village, Yemen on Monday 28 Dhû al-Qa‘dah 1172 H and died on Tuesday, 27 Jumâd al-Akhîr 1250 H at the age about 78 years. Al-Shawkânî grew up in the San‘a city, it is the capital of the republic of Yemen now. He study first time about religion from his father, then from renowed scholars in San‘a and its surrounding, he was known as a scolar who mastered the various branches of religious sciences. Such as tafsîr, h}adîth, fiqh, us}ûl al-fiqh, history, science of kalâm, philosophy, balâghah, mant}iq etc. the main issue in this article is how political thought in the book of tafsir Fath al-Qadîr is the work of Shawkânî. At the end of article, the authors found that the intended political thinking in the study of Fath al-Qadîr is about constitutional ideas. These ideas about the constitution is limited to the concept of leadership and deliberation, the concept of the right of citizen to obtain justice, and the concept pf the right of citizens to live association and assembly

  15. Oxidation behavior of Al/Cr coating on Ti2AlNb alloy at 900 °C

    Science.gov (United States)

    Yang, Zhengang; Liang, Wenping; Miao, Qiang; Chen, Bowen; Ding, Zheng; Roy, Nipon

    2018-04-01

    In this paper, the Al/Cr coating was fabricated on the surface of Ti2AlNb alloy via rf magnetron sputtering and double glow treatment to enhance oxidation resistance. The protective coating with an outer layer of Al and inner layer of Cr has great bonding strength due to the in-diffusion of Cr and the inter-diffusion between Al and Cr to form Al-Cr alloyed layer which has great hardness. Acoustic emission curve which was detected via WS-2005 scratch tester indicates the bonding strength between Al/Cr coating and substrate is great. Morphology of Ti2AlNb alloy with Al/Cr coating after scratch test shows that the scratch is smooth without disbanding, and the depth and breadth of scratch are changed uniformly. The mass change was reduced after oxidation test due to the Al/Cr protective coating. Isothermal oxidation test at 900 °C was researched. Results indicate that Al/Cr coating provided oxidation resistance of Ti2AlNb alloy with prolonged air exposure at 900 °C. Al2O3 was detected by XRD patterns and SEM images, and was formed on the surface of Ti2AlNb alloy to protect substrate during oxidation test. A certain content of Cr is beneficial for the formation of Al2O3. Besides, Cr2O3 was produced under Al2O3 by outward diffusion of Cr to protect substrate sequentially, no cracks were discovered on Al/Cr protective coating. The process of Ti outward diffusion into surface was suppressive due to integration of Cr-Ti and Al-Ti intermetallics. A steady, adherent and continuous coated layer of Al/Cr on Ti2AlNb alloy increases oxidation resistance.

  16. ¿COLOMBIA DEBE APOSTARLE AL SOFTWARE LIBRE, AL DE FUENTE ABIERTA O AL PROPIETARIO?

    Directory of Open Access Journals (Sweden)

    Luis Alberto Girón Murillo

    2014-06-01

    Full Text Available Es complejo para gestores y administradores conocer las implicaciones que la adopción de modelos de desarrollo de software tendría para una región. Este artículo ofrece una evaluación de las implicaciones dinámicas que para el desarrollo de software de una región tendría el apostar de forma excluyente al software libre, al software de fuente abierta y al software propietario. Se desarrolló un modelo de simulación en Vensim de la dinámica de sistemas en donde se evaluaron 3 escenarios: uno en donde se adopta de forma excluyente el software libre, uno en donde se adopta el software propietario y uno en donde se adopta el software de fuente abierta. Se ofrecen descripciones y explicaciones de los resultados que sugieren las potencialidades de cada uno de los modelos de desarrollo evaluados.

  17. Investigation of annealing treatment on the interfacial properties of explosive-welded Al/Cu/Al multilayer

    International Nuclear Information System (INIS)

    Honarpisheh, M.; Asemabadi, M.; Sedighi, M.

    2012-01-01

    Highlights: ► We studied explosive-welded Al/Cu/Al multilayer. ► We investigated heat treatment influence on the bond properties of Al/Cu/Al. ► Intermetallic compounds were studied using the SEM, OM and EDS analysis. ► Variations of hardness in the thickness were investigated using micro-hardness. ► Intermetallic phases such as AlCu 3 and Al 2 C create at the interface of Al/Cu/Al. -- Abstract: In this study, an Al/Cu/Al multilayer sheet was fabricated by explosive welding process and the effects of annealing temperature on the interfacial properties of explosively bonded Al/Cu bimetal have been investigated. For this purpose, hardness changes along the thickness of the samples have been measured, and the thickness and type of intermetallic compounds formed at the joining interface have been explored by means of optical microscopy (OM), scanning electron microscopy (SEM) and also energy dispersive spectroscopy (EDS). The obtained results indicate that, with the increase of the annealing temperature, the thickness of intermetallic compounds has increased and the amount of hardness along the thickness of the joining interface has diminished. In the annealed sample at 400 °C for 30 min, it was observed that intermetallic layers have formed at the interface of Al/Cu bimetals. These layers consist of the intermetallic compounds AlCu 3 , Al 2 Cu and AlCu, and their thickness gets to about 5 μm at some points. The examinations performed by the SEM, following the Vickers micro-hardness test, indicated the existence of a number of microcracks at the top and bottom interface of the sample annealed at 400 °C. This shows the formation of brittle intermetallic compounds at the joining interface, and also indicates the low ductility of these compounds.

  18. NMR evidence for Co-Al-Co molecular groups trapped in cages of Co4Al13

    International Nuclear Information System (INIS)

    Jeglic, P.; Heggen, M.; Feuerbacher, M.; Bauer, B.; Gille, P.; Haarmann, F.

    2009-01-01

    We present the results of 27 Al nuclear magnetic resonance (NMR) experiments on the phase Co 4 Al 13 . These results are compared to a recent structure model [1], which demonstrates a unique bonding for Al atoms in the Co-Al-Co molecular groups. In our measurement, two 27 Al signals were identified. The first one originates from Al atoms forming cages. The second signal corresponds to Al sites with exceptionally large almost axially symmetric quadrupole coupling. This finding is in perfect agreement with isolated Co-Al-Co molecular groups in accordance to Ref. [1].

  19. The Y-Cu-Al system

    International Nuclear Information System (INIS)

    Krachan, T.; Stel'makhovych, B.; Kuz'ma, Yu.

    2003-01-01

    The phase diagram of the Y-Cu-Al system at 820 K has been constructed using X-ray powder diffraction. The existence of earlier known ternary aluminides has been confirmed and their homogeneity regions and atomic distributions in the structures have been determined: YCu 4.6-4.0 Al 7.4-8.0 (ThMn 12 -type R I =0.049), Y 2 Cu 12.0-10.5 Al 5.0-6.5 (Th 2 Zn 17 -type R I =0.092), YCu 1.0-1.1 Al 1.0-0.9 (Fe 2 P-type R I =0.068). It has been shown that the structure of Y(Cu,Al) 3 is characterized by an ordered distribution of the Cu and Al atoms and it should be referred as Ca 3 Cu 2 Al 7 structure type (R I =0.060) besides the PuNi 3 structure type with statistical occupancies of the smaller atoms. At the investigated temperature the compound YCu 1.0-0.25 Al 3.0-3.75 (BaAl 4 -type) was not observed. However, we found the ternary aluminide with composition Y 3 Cu 2.7-2.0 Al 8.3-9.0 and related La 3 Al 11 -type (space group Immm, a=0.4192-0.4228, b=1.2423-1.2557, c=0.9812-0.9895 nm, R I =0.069). The compounds YCu 6.8 Al 4.2 (space group Fddd, Tb(Cu 0.58 Al 0.42 ) 11 -type, a=1.42755, b=1.48587, c=0.65654 nm, R I =0.062) and YCu 6.5 Al 4.5 (space group I4 1 /amd, BaCd 11 -type, a=1.02774, c=0.65838 nm, R I =0.071) have been found and structurally refined for the first time

  20. Preparation, deformation, and failure of functional Al-Sn and Al-Sn-Pb nanocrystalline alloys

    Science.gov (United States)

    Noskova, N. I.; Vil'Danova, N. F.; Filippov, Yu. I.; Churbaev, R. V.; Pereturina, I. A.; Korshunov, L. G.; Korznikov, A. V.

    2006-12-01

    Changes in the structure, hardness, mechanical properties, and friction coefficient of Al-30% Sn, Al-15% Sn-25% Pb, and Al-5% Sn-35% Pb (wt %) alloys subjected to severe plastic deformation by equal-channel angular pressing (with a force of 40 tonne) and by shear at a pressure of 5 GPa have been studied. The transition into the nanocrystalline state was shown to occur at different degrees of plastic deformation. The hardness exhibits nonmonotonic variations, namely, first it increases and subsequently decreases. The friction coefficient of the Al-30% Sn, Al-15% Sn-25% Pb, and Al-5% Sn-35% Pb alloys quenched from the melt was found to be 0.33; the friction coefficients of these alloys in the submicrocrystalline state (after equal-channel angular pressing) equal 0.24, 0.32, and 0.35, respectively. The effect of disintegration into nano-sized powders was found to occur in the Al-15% Sn-25% Pb, and Al-5% Sn-35% Pb alloys after severe plastic deformation to ɛ = 6.4 and subsequent short-time holding.

  1. Characterization of Al/Ni multilayers and their application in diffusion bonding of TiAl to TiC cermet

    International Nuclear Information System (INIS)

    Cao, J.; Song, X.G.; Wu, L.Z.; Qi, J.L.; Feng, J.C.

    2012-01-01

    The Al/Ni multilayers were characterized and diffusion bonding of TiAl intermetallics to TiC cermets was carried out using the multilayers. The microstructure of Al/Ni multilayers and TiAl/TiC cermet joint was investigated. The layered structures consisting of a Ni 3 (AlTi) layer, a Ni 2 AlTi layer, a (Ni,Al,Ti) layer and a Ni diffusion layer were observed from the interlayer to the TiAl substrate. Only one AlNi 3 layer formed at the multilayer/TiC cermet interface. The reaction behaviour of Al/Ni multilayers was characterized by means of differential scanning calorimeter (DSC) and X-ray diffraction. The initial exothermic peak of the DSC curve was formed due to the formation of Al 3 Ni and Al 3 Ni 2 phases. The reaction sequence of the Al/Ni multilayers was Al 3 Ni → Al 3 Ni 2 → AlNi → AlNi 3 and the final products were AlNi and AlNi 3 phases. The shear strength of the joint was tested and the experimental results suggested that the application of Al/Ni multilayers improved the joining quality. - Highlights: ► Diffusion bonding of TiAl to TiC cermet was realized using Al/Ni multilayer. ► The reaction sequence of the Al/Ni multilayers was Al 3 Ni → Al 3 Ni 2 → AlNi → AlNi 3 . ► The interfacial microstructure of the joint was clarified. ► The application of Al/Ni multilayers improved the joining quality.

  2. Hot Corrosion Behavior of Stainless Steel with Al-Si/Al-Si-Cr Coating

    Science.gov (United States)

    Fu, Guangyan; Wu, Yongzhao; Liu, Qun; Li, Rongguang; Su, Yong

    2017-03-01

    The 1Cr18Ni9Ti stainless steel with Al-Si/Al-Si-Cr coatings is prepared by slurry process and vacuum diffusion, and the hot corrosion behavior of the stainless steel with/without the coatings is studied under the condition of Na2SO4 film at 950 °C in air. Results show that the corrosion kinetics of stainless steel, the stainless steel with Al-Si coating and the stainless steel with Al-Si-Cr coating follow parabolic laws in several segments. After 24 h corrosion, the sequence of the mass gain for the three alloys is the stainless steel with Al-Si-Cr coating coating coating. The corrosion products of the three alloys are layered. Thereinto, the corrosion products of stainless steel without coating are divided into two layers, where the outside layer contains a composite of Fe2O3 and FeO, and the inner layer is Cr2O3. The corrosion products of the stainless steel with Al-Si coating are also divided into two layers, of which the outside layer mainly consists of Cr2O3, and the inner layer is mainly SiO2. The corrosion film of the stainless steel with Al-Si-Cr coating is thin and dense, which combines well with substrate. Thereinto, the outside layer is mainly Cr2O3, and the inside layer is Al2O3. In the matrix of all of the three alloys, there exist small amount of sulfides. Continuous and protective films of Cr2O3, SiO2 and Al2O3 form on the surface of the stainless steel with Al-Si and Al-Si-Cr coatings, which prevent further oxidation or sulfide corrosion of matrix metals, and this is the main reason for the much smaller mass gain of the two alloys than that of the stainless steel without any coatings in the 24 h hot corrosion process.

  3. Gate length scaling effect on high-electron mobility transistors devices using AlGaN/GaN and AlInN/AlN/GaN heterostructures.

    Science.gov (United States)

    Liao, S Y; Lu, C C; Chang, T; Huang, C F; Cheng, C H; Chang, L B

    2014-08-01

    Compared to AlGaN/GaN HEMT with 0.15 μm T-gate length, the AlInN/AlN/GaN one exhibits much higher current density and transconductance of 1558 mA/mm at Vd = 2 V and 330 mS/mm, respectively. The high extrinsic ft and fmax of 82 GHz and 70 GHz are extracted from AlInN/AlN/GaN HEMT. Besides, we find that the transconductance roll-off is significant in AlGaN/GaN, but largely improved in AlInN/AlN/GaN HEMT, suggesting that the high carrier density and lattice-matched epitaxial heterostructure is important to reach both large RF output power and high operation frequency, especially for an aggressively gate length scaling.

  4. Some aspects of anelastic and microplastic creep of pure Al and two Al-alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sgobba, S. (Lab. de Metallurgie Mecanique, Dept. des Materiaux, Ecole Polytechnique Federale de Lausanne (Switzerland)); Kuenzi, H.U. (Lab. de Metallurgie Mecanique, Dept. des Materiaux, Ecole Polytechnique Federale de Lausanne (Switzerland)); Ilschner, B. (Lab. de Metallurgie Mecanique, Dept. des Materiaux, Ecole Polytechnique Federale de Lausanne (Switzerland))

    1993-11-01

    Anelastic creep of pure Al, commercial Al-Cu and a binary Al-Cu alloy has been measured at room temperature by means of a high resolution laser interferometer. The irreversible component of the deformation was also quantified from measurements of the anelastic creep recovery. The dependence of the deformation-time curves on thermal treatment and cold work is analyzed. The mechanisms responsible for the room temperature anelastic creep are discussed. Materials loaded below their elastic limit can present either a pure anelastic behavior (commercial Al-Cu) or additional viscoelastic creep (pure Al, high purity Al-Cu). For commercial Al-Cu, the presence of an irreversible deformation appears to be mainly related to the state of the surface. A viscoelastic after effect has been measured for this alloy after a Cu-electroplating treatment. As a typical result for room temperature creep, the irreversible deformation depends logarithmically on load time. (orig.).

  5. Some aspects of anelastic and microplastic creep of pure Al and two Al-alloys

    International Nuclear Information System (INIS)

    Sgobba, S.; Kuenzi, H.U.; Ilschner, B.

    1993-01-01

    Anelastic creep of pure Al, commercial Al-Cu and a binary Al-Cu alloy has been measured at room temperature by means of a high resolution laser interferometer. The irreversible component of the deformation was also quantified from measurements of the anelastic creep recovery. The dependence of the deformation-time curves on thermal treatment and cold work is analyzed. The mechanisms responsible for the room temperature anelastic creep are discussed. Materials loaded below their elastic limit can present either a pure anelastic behavior (commercial Al-Cu) or additional viscoelastic creep (pure Al, high purity Al-Cu). For commercial Al-Cu, the presence of an irreversible deformation appears to be mainly related to the state of the surface. A viscoelastic after effect has been measured for this alloy after a Cu-electroplating treatment. As a typical result for room temperature creep, the irreversible deformation depends logarithmically on load time. (orig.)

  6. A study of ion damage in Al, Al/Cu and Al/Ag

    International Nuclear Information System (INIS)

    Marikar, P.

    1979-06-01

    Specimens of pure aluminium, aluminium-copper and aluminium-silver have been irradiated with 20 keV helium ions and/or 100 keV aluminium ions and the nature of the damage assessed using transmission electron microscopy. Irradiation with 20 keV helium ions to a dose of 2.7 x 10 15 ions cm -2 results in the formation of interstitial loops and helium gas bubbles. The helium bubbles were detectable only after annealing at a high temperature following irradiation. When the helium preinjected aluminium specimens were irradiated with 100 keV Al + ions to a dose of 84 dpa at temperatures above 150 0 C, voids were observed to form. At a lower dose of 64 dpa, only a high density of dislocation loops was observed. Al-1 wt% Cu alloy containing partially coherent theta' precipitates resists void formation to a considerable extent, and Al-10 wt% Ag alloy containing coherent G.P. zones offers complete resistance to both dislocation loop nucleation and void formation. The experimental results are discussed in the light of the current theories of irradiation induced damage in metals. The importance of the dislocation-sink efficiency for point defects, the gaseous impurity and the alloying elements in determining void formation is highlighted. (author)

  7. Interdiffusion between U(Mo,Pt) or U(Mo,Zr) and Al or Al A356 alloy

    International Nuclear Information System (INIS)

    Komar Varela, C.; Mirandou, M.; Arico, S.; Balart, S.; Gribaudo, L.

    2009-01-01

    Solid state reactions in chemical diffusion couples U-7 wt.%Mo-0.9 wt.%Pt/Al at 580 deg. C and U-7 wt.%Mo-0.9 wt.%Pt/Al A356 alloy, U-7 wt.%Mo-1 wt.%Zr/Al and U-7 wt.%Mo-1 wt.%Zr/Al A356 alloy at 550 deg. C were characterized. Results were obtained from optical and scanning electron microscopy, electron probe microanalysis and X-ray diffraction. The UAl 3, UAl 4 and Al 20 Mo 2 U phases were identified in the interaction layers of γU(Mo,Pt)/Al and γU(Mo,Zr)/Al diffusion couples. Al 43 Mo 4 U 6 ternary compound was also identified in γU(Mo,Zr)/Al due to the decomposition of γU(Mo,Zr) phase. The U(Al,Si) 3 and U 3 Si 5 phases were identified in the interaction layers of γU(Mo,Pt)/Al A356 and γU(Mo,Zr)/Al A356 diffusion couples. These phases are formed due to the migration of Si to the interaction layer. In the diffusion couple U(Mo,Zr)/Al A356, Zr 5 Al 3 phase was also identified in the interaction layer. The use of synchrotron radiation at Brazilian Synchrotron Light Laboratory (LNLS, CNPq, Campinas, Brazil) was necessary to achieve a complete crystallographic characterization.

  8. CuAlO2 and CuAl2O4 thin films obtained by stacking Cu and Al films using physical vapor deposition

    Science.gov (United States)

    Castillo-Hernández, G.; Mayén-Hernández, S.; Castaño-Tostado, E.; DeMoure-Flores, F.; Campos-González, E.; Martínez-Alonso, C.; Santos-Cruz, J.

    2018-06-01

    CuAlO2 and CuAl2O4 thin films were synthesized by the deposition of the precursor metals using the physical vapor deposition technique and subsequent annealing. Annealing was carried out for 4-6 h in open and nitrogen atmospheres respectively at temperatures of 900-1000 °C with control of heating and cooling ramps. The band gap measurements ranged from 3.3 to 4.5 eV. Electrical properties were measured using the van der Pauw technique. The preferred orientations of CuAlO2 and CuAl2O4 were found to be along the (1 1 2) and (3 1 1) planes, respectively. The phase percentages were quantified using a Rietveld refinement simulation and the energy dispersive X-ray spectroscopy indicated that the composition is very close to the stoichiometry of CuAlO2 samples and with excess of aluminum and deficiency of copper for CuAl2O4 respectively. High resolution transmission electron microscopy identified the principal planes in CuAlO2 and in CuAl2O4. Higher purities were achieved in nitrogen atmosphere with the control of the cooling ramps.

  9. Three-Dimensional FIB/EBSD Characterization of Irradiated HfAl3-Al Composite

    Energy Technology Data Exchange (ETDEWEB)

    Hua, Zilong; Guillen, Donna Post; Harris, William; Ban, Heng

    2016-09-01

    A thermal neutron absorbing material, comprised of 28.4 vol% HfAl3 in an Al matrix, was developed to serve as a conductively cooled thermal neutron filter to enable fast flux materials and fuels testing in a pressurized water reactor. In order to observe the microstructural change of the HfAl3-Al composite due to neutron irradiation, an EBSD-FIB characterization approach is developed and presented in this paper. Using the focused ion beam (FIB), the sample was fabricated to 25µm × 25µm × 20 µm and mounted on the grid. A series of operations were carried out repetitively on the sample top surface to prepare it for scanning electron microscopy (SEM). First, a ~100-nm layer was removed by high voltage FIB milling. Then, several cleaning passes were performed on the newly exposed surface using low voltage FIB milling to improve the SEM image quality. Last, the surface was scanned by Electron Backscattering Diffraction (EBSD) to obtain the two-dimensional image. After 50 to 100 two-dimensional images were collected, the images were stacked to reconstruct a three-dimensional model using DREAM.3D software. Two such reconstructed three-dimensional models were obtained from samples of the original and post-irradiation HfAl3-Al composite respectively, from which the most significant microstructural change caused by neutron irradiation apparently is the size reduction of both HfAl3 and Al grains. The possible reason is the thermal expansion and related thermal strain from the thermal neutron absorption. This technique can be applied to three-dimensional microstructure characterization of irradiated materials.

  10. The Genyornis Egg: Response to Miller et al.'s commentary on Grellet-Tinner et al., 2016

    Science.gov (United States)

    Grellet-Tinner, Gerald; Spooner, Nigel A.; Handley, Warren D.; Worthy, Trevor H.

    2017-04-01

    Williams (1981) and Williams and Rich (1991) attributed Australian Quaternary fossil eggshell that differed from that of emu Dromaius novaehollandiae to the extinct bird Genyornis newtoni without any osteological or embryonic support. Such association by proximity or abundance mirrors the case of the mistaken association of oviraptor eggs to Protoceratops in the 1920's by Andrews (Grellet-Tinner and Makovicky, 2006). No other candidate species was considered, and this attribution has been unchallenged and followed by everyone thereafter. Much research has been done on this Australian eggshell, with one result being that the extinction of the parent of this eggshell is the most well documented for a taxon in Australia (e.g., Miller et al., 1999, 2005). Grellet-Tinner et al. (2016) raised several problems with the identity of the eggshell Williams (1981) attributed to Genyornis newtoni and suggested that extinct megapodes of the genus Progura were the more likely layer of this eggshell type, therein referred to as ;putative Genyornis oological material; (PGOM). Miller et al. (2017) challenged our hypothesis stating that ;Based on the dimensions of the reconstructed Spooner Egg,Grellet-Tinner et al. (2016)argue that PGOM is too small for a bird with the body mass estimated for Genyornis (168-275 kg) … …[and] …. None of the additional PGOM observations reported byGrellet-Tinner et al. (2016)are inconsistent with a Genyornis parent;. Here we take the opportunity to respond to their critique, the basis of which resolves into a few points, which we address in turn.

  11. Characterization of Al/Ni multilayers and their application in diffusion bonding of TiAl to TiC cermet

    Energy Technology Data Exchange (ETDEWEB)

    Cao, J., E-mail: cao_jian@hit.edu.cn [State Key Lab of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin, 150001 (China); Center for Composite Materials and Structures, Harbin Institute of Technology, Harbin, 150001 (China); Song, X.G. [State Key Lab of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin, 150001 (China); Wu, L.Z. [Center for Composite Materials and Structures, Harbin Institute of Technology, Harbin, 150001 (China); Qi, J.L.; Feng, J.C. [State Key Lab of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin, 150001 (China)

    2012-02-29

    The Al/Ni multilayers were characterized and diffusion bonding of TiAl intermetallics to TiC cermets was carried out using the multilayers. The microstructure of Al/Ni multilayers and TiAl/TiC cermet joint was investigated. The layered structures consisting of a Ni{sub 3}(AlTi) layer, a Ni{sub 2}AlTi layer, a (Ni,Al,Ti) layer and a Ni diffusion layer were observed from the interlayer to the TiAl substrate. Only one AlNi{sub 3} layer formed at the multilayer/TiC cermet interface. The reaction behaviour of Al/Ni multilayers was characterized by means of differential scanning calorimeter (DSC) and X-ray diffraction. The initial exothermic peak of the DSC curve was formed due to the formation of Al{sub 3}Ni and Al{sub 3}Ni{sub 2} phases. The reaction sequence of the Al/Ni multilayers was Al{sub 3}Ni {yields} Al{sub 3}Ni{sub 2} {yields} AlNi {yields} AlNi{sub 3} and the final products were AlNi and AlNi{sub 3} phases. The shear strength of the joint was tested and the experimental results suggested that the application of Al/Ni multilayers improved the joining quality. - Highlights: Black-Right-Pointing-Pointer Diffusion bonding of TiAl to TiC cermet was realized using Al/Ni multilayer. Black-Right-Pointing-Pointer The reaction sequence of the Al/Ni multilayers was Al{sub 3}Ni {yields} Al{sub 3}Ni{sub 2} {yields} AlNi {yields} AlNi{sub 3}. Black-Right-Pointing-Pointer The interfacial microstructure of the joint was clarified. Black-Right-Pointing-Pointer The application of Al/Ni multilayers improved the joining quality.

  12. UNDERSTANDING THE MULTIDIMENSIONAL ISLAMIC FAITH THROUGH ‘ABD AL-GHANI AL-NABULUSI’S MYSTICAL PHILOSOPHY

    Directory of Open Access Journals (Sweden)

    Naoki Yamamoto

    2013-12-01

    Full Text Available This paper tries to present a new perspective on Islamic faith and Muslim identity to Muslim minorities who are challenged in practicing or following Islamic law in non-Islamic countries or non-Muslims in the contemporary world. It will uncover the multidimensional perspective of the concept of faith based on sin (dhanb and repentance (tawbah through the mystical philosophy of a Syrian scholar, Abd al-Ghani al-Nabulusi (d. 1143/1741 of the 18th century Ottoman Damascus who contributed to the field of Sufism particularly based on Ibn ‘Arabi’s thought of wahdat al-wujud (oneness of being and insan kamil (the perfect man. Nabulusi believes that anyone who lived during the inexistence of prophet’s revelation, inhabited an isolated place cut off from information about Islam, or lived in dar al-harb and did not make a hijra to dar al-islam could not be regarded as sinful in their deeds. However, faith in Allah is essential and infidelity is not forgiven regardless whether or not they live in dar al-islam or dar al-harb. Further, Nabulusi insists that true faith can be achieved by understanding the sin of existence; the ignorance of the difference of existence between Allah and men.  [Artikel ini menjelaskan identitas keberagamaan umat Islam minoritas yang dituntut untuk menerapkan syariat, namun harus hidup di negara non-muslim, dengan mendiskusikan perspektif multidimensional terhadap konsep dosa dan tobat seperti dikembangkan oleh Abd al-Ghanī al-Nabulusī (1143/1741, seorang sufi pemikir Syria, khususnya  wahdat al-wujūd dan insan kamil, yang hidup di masa kesultanan Usmani di Damaskus. Nabulusī berkeyakinan bahwa siapa saja yang hidup sebelum turunnya wahyu di masa Nabi, hidup di daerah terpencil yang tidak mengenal Islam, atau hidup di dar al-harb dan tidak hijrah ke dar al-islam, tidaklah dibebani dosa atas perbuatannya. Namun demikian, iman kepada Allah amatlah penting dan kekufuran tidaklah dimaafkan, baik seseorang tersebut hidup

  13. PRECIPITATION HARDENING IN B2-ORDERED NiAl BY Ni2AlTiCOMPOUND

    Institute of Scientific and Technical Information of China (English)

    W.H. Tian; K. Ohishi; M. Nemoto

    2001-01-01

    Microstructural variations and correlated hardness changes in B2-ordered NiAl containing fine precipitation of Ni2AlTi have been investigated by means of transmission electron microscopy (TEM) and hardness tests. The amount of age hardening is not large as compared to the large microstructural variations during aging. TEM observations have revealed that the L21-type Ni2AlTi precipitates keep a lattice coherency with the NiAl matrix at the beginning of aging. By longer periods of aging Ni2AlTi precipitates lose their coherency and change their morphology to the globular ones surrounded by misfit dislocations. The temperature dependence of the yield strength of precipitate-containing B2-ordered NiAl was investigated by compression tests over the temperature range of 873-1273K. The fine precipitation of Ni2AlTi was found to enhance greatly the yield strength and the high-temperature strength is comparison with that of superalloy Mar-M200.``

  14. Rupture of Al matrix in U-Mo/Al dispersion fuel by fission induced creep

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Gwan Yoon; Sohn, Dong Seong [UNIST, Daejeon (Korea, Republic of); Kim, Yeon Soo [Argonne National Laboratory, Argonnge (United States); Lee, Kyu Hong [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    This phenomenon was found specifically in the dispersion fuel plate with Si addition in the Al matrix to suppress interaction layer (IL) formation between UMo and Al. It is known that the stresses induced by fission induced swelling in U-Mo fuel particles are relieved by creep deformation of the IL, surrounding the fuel particles, that has a much higher creep rate than the Al matrix. Thus, when IL growth is suppressed, the stress is instead exerted on the Al matrix. The observed rupture in the Al matrix is believed to be caused when the stress exceeded the rupture strength of the Al matrix. In this study, the possibility of creep rupture of the Al matrix between the neighboring U-Mo fuel particles was examined using the ABAQUS finite element analysis (FEA) tool. The predicted rupture time for a plate was much shorter than its irradiation life indicating a rupture during the irradiation. The higher stress leads Al matrix to early creep rupture in this plate for which the Al matrix with lower creep strain rate does not effectively relieve the stress caused by the swelling of the U-Mo fuel particles. For the other plate, no rupture was predicted for the given irradiation condition. The effect of creeping of the continuous phase on the state of stress is significant.

  15. Effect of Al and AlP on the microstructure of Mn-30 wt.%Si alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wu Yuying [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jing Shi Road 73, Jinan 250061 (China); Liu Xiangfa [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jing Shi Road 73, Jinan 250061 (China)], E-mail: xfliu@sdu.edu.cn

    2008-04-15

    Effect of Al and AlP particles on the microstructure of near eutectic Mn-Si alloy (Mn-30 wt.%Si) was studied by Electron Probe Micro-analyzer (EPMA) and Differential Scanning Calorimeter (DSC). Crystal lattice correspondence analyses show that both Al and AlP have good lattice matching coherence relationships with MnSi phase, and the addition of Al and AlP particles results in an abnormal eutectic structure, i.e. the eutectic constitution MnSi and Mn{sub 5}Si{sub 3} precipitate separately: MnSi precipitates firstly, and then the Mn{sub 5}Si{sub 3} phase.

  16. Elastocaloric effect in CuAlZn and CuAlMn shape memory alloys under compression

    OpenAIRE

    Qian, Suxin; Geng, Yunlong; Wang, Yi; Pillsbury, Thomas E.; Hada, Yoshiharu; Yamaguchi, Yuki; Fujimoto, Kenjiro; Hwang, Yunho; Radermacher, Reinhard; Cui, Jun; Yuki, Yoji; Toyotake, Koutaro; Takeuchi, Ichiro

    2016-01-01

    This paper reports the elastocaloric effect of two Cu-based shape memory alloys: Cu68Al16Zn16 (CuAlZn) and Cu73Al15Mn12 (CuAlMn), under compression at ambient temperature. The compression tests were conducted at two different rates to approach isothermal and adiabatic conditions. Upon unloading at a strain rate of 0.1 s−1 (adiabatic condition) from 4% strain, the highest adiabatic temperature changes (ΔTad) of 4.0 K for CuAlZn and 3.9 K for CuAlMn were obtained. The maximum stress and hystere...

  17. Formation of Al3Ti/Mg composite by powder metallurgy of Mg-Al-Ti system.

    Science.gov (United States)

    Yang, Zi R; Qi Wang, Shu; Cui, Xiang H; Zhao, Yu T; Gao, Ming J; Wei, Min X

    2008-07-01

    An in situ titanium trialuminide (Al 3 Ti)-particle-reinforced magnesium matrix composite has been successfully fabricated by the powder metallurgy of a Mg-Al-Ti system. The reaction processes and formation mechanism for synthesizing the composite were studied by differential scanning calorimetry (DSC), x-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS). Al 3 Ti particles are found to be synthesized in situ in the Mg alloy matrix. During the reaction sintering of the Mg-Al-Ti system, Al 3 Ti particles are formed through the reaction of liquid Al with as-dissolved Ti around the Ti particles. The formed intermetallic particles accumulate at the original sites of the Ti particles. As sintering time increases, the accumulated intermetallic particles disperse and reach a relatively homogeneous distribution in the matrix. It is found that the reaction process of the Mg-Al-Ti system is almost the same as that of the Al-Ti system. Mg also acts as a catalytic agent and a diluent in the reactions and shifts the reactions of Al and Ti to lower temperatures. An additional amount of Al is required for eliminating residual Ti and solid-solution strengthening of the Mg matrix.

  18. Al-‘Alāqah baina Ushūl al-Fiqh wa Maqāshidi al-Sharīah wa al-Da’wah ilā Ta’sīsi ‘Ilmi al-Maqāshid

    Directory of Open Access Journals (Sweden)

    Anggraini Binti Ramli

    2016-12-01

    Full Text Available The study of Maqāshid sharīa is an important point in the discussion of Islamic legal theory (ushūl al-fiqh. Serious debates began to emerge in the 19th century among Islamic jurists concerning the position of maqāshid sharīa. At least, there are three important debates in the history; first, whether maqāshid is part of the discussion ushūl al-fiqh; second, is maqāshid sharīa built upon a foundation of classical Islamic jurisprudence (fiqh; and third, whether the maqāshid sharīa study is able to become an independent science that is separated from the study of classical Islamic jurisprudence. This article tries to present a discussion of the three paradigms by employing a descriptive-analytic method. The results of this study uncover that the study of maqāshid sharīa is like two sides of one coin; theoretically it is a distinctive study from ushūl al-fiqh, but it cannot be separated from one another. Ushūl al-fiqh has become the foundation to find out more details about the study of maqashid sharia. The separation between classical Islamic jurisprudence (fiqh and maqāshid sharīa study conducted by Islamic jurists is a relative separation.

  19. Solutional Landforms of Gabal Al-Qaraha, the Oasis of Al-Hasa, Saudi Arabia

    OpenAIRE

    Embabi, Nabil S.

    1981-01-01

    Jabal Al-Qarah is one of the small outlier hills at the Oasis of Al-Hasa, lying at about lOkm ENE of Al-Hafuf Town. The solutional forms of Al-Qarah hill discussed in this paper are as follows : 1. A calcareous duricrust which covers the top and some of the slopes of the hill. 2. Rock Pillars which are long columns of white lime-stone. 3. Huge crevasses which are wide erosional openings along vertical joints. 4. Narrow, sinuous caves inside the hill. 5. Pedestal rocks with mushroo...

  20. Comparison on the interaction of Al3+/nano-Al13 with calf thymus DNA /salmon sperm DNA

    Science.gov (United States)

    Ma, Fei; Ma, Yue; Du, Changwen; Yang, Xiaodi; Shen, Renfang

    2015-11-01

    The conformation change, binding mode and binding site between Al3+/nano-Al13 and calf thymus DNA/salmon sperm DNA were investigated by UV-vis absorption, FTIR spectra, Raman spectroscopy and CD spectra, as well as melting curves measurement. The UV-vis spectra and circular dichroism spectra results suggested that the phosphate group structure was changed when Al3+ interacted with DNA, while the double-helix was distorted when nano-Al13 interacted with DNA. The FTIR and Raman spectroscopy revealed that the binding sites were Al3+ … PO2, Al3+ … N7/guanine PO2 … Al13 … N7-C8/guanine with calf thymus DNA, and Al3+ … N3-O2/cytosine, Al3+ … N7-C8/guanine, PO2 … Al13 … N7-C8/guanine, PO2 … Al13 … N1/adenine with salmon sperm DNA, respectively. The electrostatic binding was existed between Al3+ and DNA, and the electrostatic binding and complexing were found between nano-Al13 and DNA.

  1. Bukti Kebenaran Al-quran

    OpenAIRE

    Aliyah, Sri

    2015-01-01

    Al Quran is the greatest miracles of Muhammad SAW as the direction of humankind in order to reach eternal happiness. Scientific evidences show that Al Quran has the truth massages, although it was released far before the finding of modern sciences. The researches continue to study the truth of Al Quran an it revealed the historical fact.

  2. Sintering of (Ni,Mg)(Al,Fe)2O4 Materials and their Corrosion Process in Na3AlF6-AlF3-K3AlF6 Electrolyte

    Science.gov (United States)

    Xu, Yibiao; Li, Yawei; Yang, Jianhong; Sang, Shaobai; Wang, Qinghu

    2017-06-01

    The application of ledge-free sidewalls in the Hall-Héroult cells can potentially reduce the energy requirement of aluminum production by about 30 pct (Nightingale et al. in J Eur Ceram, 33:2761-2765, 2013). However, this approach poses great material challenges since such sidewalls are in direct contact with corrosive electrolyte. In the present paper, (Ni,Mg)(Al,Fe)2O4 materials were prepared using fused magnesia, reactive alumina, nickel oxide, and iron oxide powders as the starting materials. The sintering behaviors of specimens as well as their corrosion resistance to molten electrolyte have been investigated by means of X-ray diffraction and scanning electron microscope. The results show that after firing at temperature ranging from 1673 K (1400 °C) up to 1873 K (1600 °C), all the specimens prepared are composed of single-phase (Ni,Mg)(Al,Fe)2O4 composite spinel, the lattice parameter of which increases with increasing Fe3+ ion concentration. Increasing the iron oxide content enhances densification of the specimens, which is accompanied by the formation of homogeneously distributed smaller pores in the matrix. The corrosion tests show that corrosion layers consist of fluoride and Ni(Al,Fe)2O4 composite spinel grains are produced in specimens with Fe/Al mole ratio no more than 1, whereas dense Ni(Al,Fe)2O4 composite spinel layers are formed on the surface of the specimens with Fe/Al mole ratio more than 1. The dense Ni(Al,Fe)2O4 composite spinel layers formed improve the corrosion resistance of the specimens by inhibiting the infiltration of electrolyte and hindering the chemical reaction between the specimen and electrolyte.

  3. Synthesis of Al(OH3 Nanostructures from Al(OH3 Microagglomerates via Dissolution-Precipitation Route

    Directory of Open Access Journals (Sweden)

    Bo Yu

    2013-01-01

    Full Text Available A facile method was developed to synthesize Al(OH3 nanostructures from Al(OH3 microagglomerates by dissolution in 9.0 mol·L−1 NaOH at 115°C followed by dilution and aging of the solution at room temperature. The influence of Al(OH3 nanoseed and surfactants as sodium dodecyl sulfate (SDS, polyethylene glycol 6000 (PEG6000, and cetyltrimethylammonium bromide (CTAB on the formation of the Al(OH3 nano-structures was investigated. The experimental results indicated that the Al(OH3 microspheres composed of nanoparticles were prepared in the blank experiment, while dispersive Al(OH3 nano-particles with a diameter of 80–100 nm were produced in the presence of Al(OH3 nano-seed and CTAB.

  4. Effects of Al content on structure and mechanical properties of hot-rolled ZrTiAlV alloys

    International Nuclear Information System (INIS)

    Liang, S.X.; Yin, L.X.; Che, H.W.; Jing, R.; Zhou, Y.K.; Ma, M.Z.; Liu, R.P.

    2013-01-01

    Highlights: • Phase structure is greatly dependent on the Al content. • Intermetallic compound will precipitates while Al content is over 6.9 wt%. • Equiaxed α-phase grains present in the hot-rolled alloy with 6.9 wt% Al. • Alloys with Al content from 3.3 wt% to 5.6 wt% have good mechanical properties. - Abstract: Zirconium alloys show attractive properties for astronautic applications where the most important factors are anti-irradiation, corrosion resistance, anti-oxidant, very good strength-to-weight ratio. The effects of Al content (2.2–6.9 wt%) on structure and mechanical properties of the hot-rolled ZrTiAlV alloy samples were investigated in this study. Each sample of the hot-rolled ZrTiAlV alloys with Al contents from 2.2 wt% to 5.6 wt% is composed of the α phase and β phase, meanwhile, the relative content of the α phase increased with the Al content. However, the (ZrTi) 3 Al intermetallic compound was observed as the Al content increased to 6.9 wt%. Changes of phase compositions and structure with Al content distinctly affected mechanical properties of ZrTiAlV alloys. Yield strength of the alloy with 2.2 wt% Al is below 200 MPa. As Al content increased to 5.6 wt%, the yield strength, tensile strength and elongation of the examined alloy are 1088 MPa, 1256 MPa and 8%, respectively. As Al content further increased to 6.9 wt%, a rapid decrease in ductility was observed as soon as the (ZrTi) 3 Al intermetallic compound precipitated. Results show that the ZrTiAlV alloys with Al contents between 3.3 wt% and 5.6 wt% have excellent mechanical properties

  5. Relationship between Al content and substitution mechanism of Al-bearing anhydrous bridgmanites

    Science.gov (United States)

    Noda, M.; Inoue, T.; Kakizawa, S.

    2017-12-01

    It is considered that two substitution mechanisms, Tschermak substitution and oxygen vacancy substitution, exist in MgSiO3 bridgmanite for the incorporation of Al in anhydrous condition. Kubo and Akaogi (2000) has conducted the phase equilibrium experiment in the system MgSiO3-Al2O3, and established the phase diagram up to 28 GPa. However the careful observation in the bridgmanite shows that the chemical compositions are slightly deviated from Tschermak substitution join. The same tendency can be also observed in the run products by Irifune et al. (1996). This result indicates that pure Tschermak substitution bridgmanite cannot be stable even in the MgSiO3-Al2O3 join experiment. However, the previous studies used powder samples as the starting materials, so the absorbed water may affect the results. Therefore, we tried to conduct the experiment in the join MgSiO3-Al2O3 in extremely anhydrous condition to clarify whether the pure Tschermak substitution bridgmanite can be stable or not. In addition, we also examined the stability of oxygen vacancy bridgmanite in the extremely anhydrous condition for the comparison. The high pressure synthesis experiments were conducted at 28 GPa and 1600-1700° for 1hour using a Kawai-type multi-anvil apparatus. Four different Al content samples were prepared as the starting materials along the ideal substitution line of Tschermak (Al=0.025, 0.05, 0.1, 0.15 mol) and oxygen-vacancy (Al=0.025, 0.05, 0.075, 0.1 mol) substitutions, respectively (when total cation of 2). The glass rods were used as the starting materials to eliminate the absorbed water on the sample surface. The chemical compositions of the synthesized bridgmanite could not be measured by EPMA because of small grain size less than submicron. Therefore the chemical compositions were estimated from the result of the XRD pattern by subtracting the amount of the other phases. The estimated chemical compositions of Tschermak substitution bridgmanites were consistent with the

  6. Seis nuevas inscripciones latinas de la Muralla de Segovia

    Directory of Open Access Journals (Sweden)

    Juan SANTOS YANGUAS

    2009-10-01

    Full Text Available RESUMEN: En este artículo damos a conocer seis nuevas inscripciones latinas de la mutalla de Segovia. Se trata de cuatro estelas de granito y dos bloques de caliza. Estas inscripciones están muy deterioradas y hemos utilizado para leerlas papel-aluminio, en el cual, al contacto con la piedra, quedan impresas las letras. Unicamente está completa, aunque borrada en parte, una de ellas, de la cual ofrecemos el testimonio de dos fotografías.ABSTRACT: In this article are published six new roman inscriptions from the wall at Segovia. They are four granite stellae and two limestone blocks. As all they are very damaged it was necessary to use a sheet of aluminium-paper; when the sheet is pressed over the stone-surface, the few traces of the letters are more easier to be read. Two fotogtaphs illustrate on the only inscription which is wholy conserved, being its icxt unfortunately partly disappeared.

  7. Burden of rare variants in ALS genes influences survival in familial and sporadic ALS.

    Science.gov (United States)

    Pang, Shirley Yin-Yu; Hsu, Jacob Shujui; Teo, Kay-Cheong; Li, Yan; Kung, Michelle H W; Cheah, Kathryn S E; Chan, Danny; Cheung, Kenneth M C; Li, Miaoxin; Sham, Pak-Chung; Ho, Shu-Leong

    2017-10-01

    Genetic variants are implicated in the development of amyotrophic lateral sclerosis (ALS), but it is unclear whether the burden of rare variants in ALS genes has an effect on survival. We performed whole genome sequencing on 8 familial ALS (FALS) patients with superoxide dismutase 1 (SOD1) mutation and whole exome sequencing on 46 sporadic ALS (SALS) patients living in Hong Kong and found that 67% had at least 1 rare variant in the exons of 40 ALS genes; 22% had 2 or more. Patients with 2 or more rare variants had lower probability of survival than patients with 0 or 1 variant (p = 0.001). After adjusting for other factors, each additional rare variant increased the risk of respiratory failure or death by 60% (p = 0.0098). The presence of the rare variant was associated with the risk of ALS (Odds ratio 1.91, 95% confidence interval 1.03-3.61, p = 0.03), and ALS patients had higher rare variant burden than controls (MB, p = 0.004). Our findings support an oligogenic basis with the burden of rare variants affecting the development and survival of ALS. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  8. Influence of Al grain boundaries segregations and La-doping on embrittlement of intermetallic NiAl

    Energy Technology Data Exchange (ETDEWEB)

    Kovalev, Anatoly I., E-mail: a_kovalev@sprg.ru; Wainstein, Dmitry L.; Rashkovskiy, Alexander Yu.

    2015-11-01

    Highlights: • We investigated Al grain boundaries segregations in ordered pure and La-doped NiAl. • Structural segregation of Al decreases critical strain for brittle cracks nucleation. • La alloying sharply improves plasticity of NiAl intermetallic. • Metallicity of interatomic bonds on grain boundaries increases at La alloying. • We have experimentally measured by EELFS that La atoms are located in Al sublattice. - Abstract: The microscopic nature of intergranular fracture of NiAl was experimentally investigated by the set of electron spectroscopy techniques. The paper demonstrates that embrittlement of NiAl intermetallic compound is caused by ordering of atomic structure that leads to formation of structural aluminum segregations at grain boundaries (GB). Such segregations contain high number of brittle covalent interatomic bonds. The alloying by La increases the ductility of material avoiding Al GB enrichment and disordering GB atomic structure. The influence of La alloying on NiAl mechanical properties was investigated. GB chemical composition, atomic and electronic structure transformations after La doping were investigated by AES, XPS and EELFS techniques. To qualify the interatomic bonds metallicity the Fermi level (E{sub F}) position and electrons density (n{sub eff}) in conduction band were determined in both undoped and doped NiAl. Basing on experimental results the physical model of GB brittleness formation was proposed.

  9. Heterogeneous nucleation of solid Al from the melt by Al 3 Ti : Molecular dynamics simulations

    KAUST Repository

    Wang, Junsheng; Horsfield, Andrew; Lee, Peter D.; Brommer, Peter

    2010-01-01

    It has been known experimentally for some time that Al3 Ti is a powerful nucleant for the solidification of aluminum from the melt; however, a full microscopic understanding is still lacking. To develop this understanding, we have performed molecular dynamics simulations of the nucleation and early stages of growth using published embedded atom method potentials for Al-Ti, but modified by us to stabilize the D 022 structure. We discover that Al3 Ti can indeed be very effective in promoting the growth of solid Al but the manner in which growth takes place depends sensitively on the surface on which the Al nucleates. In particular, complete growth of solid Al from the liquid on the (001) and (110) surfaces of Al3 Ti occurs at a lower temperature than on the (112) surface. This anisotropy agrees with observations in previous experiments. We explain this observation in terms of interfacial energies. On the preferential (111) surface of Al the solid-liquid interfacial energy is highest while the solid-vacuum energy is lowest. Our simulations also show that the extent of ordering taking place in liquid Al close to the Al 3 Ti substrate above the melting point correlates well with the effectiveness of the substrate as a nucleant below the melting temperature: this could provide a computationally efficient scheme to identify good nucleants. © 2010 The American Physical Society.

  10. Heterogeneous nucleation of solid Al from the melt by Al 3 Ti : Molecular dynamics simulations

    KAUST Repository

    Wang, Junsheng

    2010-10-27

    It has been known experimentally for some time that Al3 Ti is a powerful nucleant for the solidification of aluminum from the melt; however, a full microscopic understanding is still lacking. To develop this understanding, we have performed molecular dynamics simulations of the nucleation and early stages of growth using published embedded atom method potentials for Al-Ti, but modified by us to stabilize the D 022 structure. We discover that Al3 Ti can indeed be very effective in promoting the growth of solid Al but the manner in which growth takes place depends sensitively on the surface on which the Al nucleates. In particular, complete growth of solid Al from the liquid on the (001) and (110) surfaces of Al3 Ti occurs at a lower temperature than on the (112) surface. This anisotropy agrees with observations in previous experiments. We explain this observation in terms of interfacial energies. On the preferential (111) surface of Al the solid-liquid interfacial energy is highest while the solid-vacuum energy is lowest. Our simulations also show that the extent of ordering taking place in liquid Al close to the Al 3 Ti substrate above the melting point correlates well with the effectiveness of the substrate as a nucleant below the melting temperature: this could provide a computationally efficient scheme to identify good nucleants. © 2010 The American Physical Society.

  11. Strength of Al and Al-Mg/alumina bonds prepared using ultrahigh vacuum diffusion bonding

    International Nuclear Information System (INIS)

    King, W.E.; Campbell, G.H.; Wien, W.L.; Stoner, S.L.

    1994-01-01

    The authors have measured the cross-breaking strength of Al and Al-Mg alloys bonded with alumina. Diffusion bonding of Al and Al-Mg alloys requires significantly more bonding time than previously thought to obtain complete bonding. In contrast to previous diffusion bonding studies, fracture morphologies are similar to those obtained in bonds formed by liquid phase reaction; i.e., bonds are as strong or stronger than the ceramic; and fracture tends to propagate in the metal for pure Al and near the interface in the ceramic for the alloys. There are indications that the fracture morphology depends on Mg content and therefore on plasticity in the metal

  12. Wear protection in cutting tool applications by PACVD (Ti,Al)N and Al2O3 coatings

    International Nuclear Information System (INIS)

    Kathrein, M.; Heiss, M.; Rofner, R.; Schleinkofer, U.; Schintlmeister, W.; Schatte, J.; Mitterer, C.

    2001-01-01

    Various (Ti,Al)N-, Al 2 O 3 -, and (Ti,Al)N/Al 2 O 3 multilayer coatings were deposited onto cemented carbide cutting tool inserts by a plasma assisted chemical vapor deposition (PACVD) technique. Al 2 O 3 coatings were deposited using the gaseous mixture AlCl 3 , Ar, H 2 , and O 2 . (Ti,Al)N intermediate layers were deposited in the same device using the process mentioned and the gases AICl 3 , Ar, H 2 , TiCl 4 and N 2 . The unique properties of (Ti,Al)N/Al 2 O 3 multilayer coatings result in superior wear protection for cutting inserts applied in severe multifunction cutting processes. The influence of different deposition temperatures an structure and properties of the coatings like crystallographic phases, chemical composition, mechanical and technological properties is shown. PACVD (Ti,Al)N/Al 2 O 3 coated cutting inserts with fine grained crystalline α/κ-Al 2 O 3 offer performance advantages which are superior with respect to coatings deposited by chemical vapor deposition (CVD) due to the low deposition temperature applied. (author)

  13. Current transport mechanism in graphene/AlGaN/GaN heterostructures with various Al mole fractions

    Science.gov (United States)

    Pandit, Bhishma; Seo, Tae Hoon; Ryu, Beo Deul; Cho, Jaehee

    2016-06-01

    The current transport mechanism of graphene formed on AlxGa1-xN/GaN heterostructures with various Al mole fractions (x = 0.15, 0.20, 0.30, and 0.40) is investigated. The current-voltage measurement from graphene to AlGaN/GaN shows an excellent rectifying property. The extracted Schottky barrier height of the graphene/AlGaN/GaN contacts increases with the Al mole fraction in AlGaN. However, the current transport mechanism deviates from the Schottky-Mott theory owing to the deterioration of AlGaN crystal quality at high Al mole fractions confirmed by reverse leakage current measurement.

  14. Current transport mechanism in graphene/AlGaN/GaN heterostructures with various Al mole fractions

    Directory of Open Access Journals (Sweden)

    Bhishma Pandit

    2016-06-01

    Full Text Available The current transport mechanism of graphene formed on AlxGa1−xN/GaN heterostructures with various Al mole fractions (x = 0.15, 0.20, 0.30, and 0.40 is investigated. The current–voltage measurement from graphene to AlGaN/GaN shows an excellent rectifying property. The extracted Schottky barrier height of the graphene/AlGaN/GaN contacts increases with the Al mole fraction in AlGaN. However, the current transport mechanism deviates from the Schottky-Mott theory owing to the deterioration of AlGaN crystal quality at high Al mole fractions confirmed by reverse leakage current measurement.

  15. Assessment of phase constitution on the Al-rich region of rapidly solidified Al-Co-Fe-Cr alloys

    International Nuclear Information System (INIS)

    Wolf, W.; Bolfarini, C.; Kiminami, C.S.; Botta, W.J.

    2016-01-01

    The formation of quasicrystalline approximants in rapidly solidified Al-Co-Fe-Cr alloys was investigated. Alloys of atomic composition Al 71 Co 13 Fe 8 Cr 8 , Al 77 Co 11 Fe 6 Cr 6 and Al 76 Co 19 Fe 4 Cr 1 were produced using melt spinning and arc melting methods and their microstructural characterization was carried out by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Up to the present there is no consensus in the literature regarding the formation of quasicrystalline phase or quasicrystalline approximants in the Al 71 Co 13 Fe 8 Cr 8 alloy. This work presents, for the first time, a detailed structural characterization of selected alloys in the Al-Co-Fe-Cr system close to the atomic composition Al 71 Co 13 Fe 8 Cr 8 . The results indicated the samples to be composed, mostly, by two intermetallic phases, which are quaternary extensions of Al 5 Co 2 and Al 13 Co 4 and are quasicrystalline approximants. Although the Al 5 Co 2 phase has already been reported in the Al 71 Co 13 Fe 8 Cr 8 alloy, the presence of the monoclinic Al 13 Co 4 is now identified for the first time in the as cast state. In the binary Al-Co system a quasicrystalline phase is known to form in a rapidly solidified alloy with composition close to the monoclinic and orthorhombic Al 13 Co 4 phases. This binary quasicrystalline phase presents an average valence electron per atom (e/a) between 1.7 and 1.9; thus, in addition to the Al 71 Co 13 Fe 8 Cr 8 alloy, the compositions Al 77 Co 11 Fe 6 Cr 6 and Al 76 Co 19 Fe 4 Cr 1 were chosen to be within the region of formation of the quaternary extension of the Al 13 Co 4 phase and also within the (e/a) of 1.7 to 1.9. However, no quasicrystalline phase is present in any of the studied alloys. The Al-Co-Fe-Cr system, around the compositions studied, is composed of quaternary extensions of Al-Co intermetallic phases, which present solubility of Fe and Cr at Co atomic sites. - Highlights: •The Al rich region of the Al

  16. Comparison of ALS functionality and plant growth in ALS-inhibitor susceptible and resistant Myosoton aquaticum L.

    Science.gov (United States)

    Liu, Weitang; Bai, Shuang; Jia, Sisi; Guo, Wenlei; Zhang, Lele; Li, Wei; Wang, Jinxin

    2017-10-01

    Herbicide target-site resistance mutations may cause pleiotropic effects on plant ecology and physiology. The effect of several known (Pro197Ser, Pro197Leu Pro197Ala, and Pro197Glu) target-site resistance mutations of the ALS gene on both ALS functionality and plant vegetative growth of weed Myosoton aquaticum L. (water chickweed) have been investigated here. The enzyme kinetics of ALS from four purified water chickweed populations that each homozygous for the specific target-site resistance-endowing mutations were characterized and the effect of these mutations on plant growth was assessed via relative growth rate (RGR) analysis. Plants homozygous for Pro197Ser and Pro197Leu exhibited higher extractable ALS activity than susceptible (S) plants, while all ALS mutations with no negative change in ALS kinetics. The Pro197Leu mutation increased ALS sensitivity to isoleucine and valine, and Pro197Glu mutation slightly increased ALS sensitivity to isoleucine. RGR results indicated that none of these ALS resistance mutations impose negative pleiotropic effects on relative growth rate. However, resistant (R) seeds had a lowed germination rate than S seeds. This study provides baseline information on ALS functionality and plant growth characteristics associated with ALS inhibitor resistance-endowing mutations in water chickweed. Copyright © 2017. Published by Elsevier Inc.

  17. AL FIKR AL BALAGHI FI AL MA’ĂNI ‘INDA AS SAKĂKI FI KITABIHI MIFTAHUL ULUM DIRĂSAH BALAGHIYYAH

    Directory of Open Access Journals (Sweden)

    Talqis Nurdianto

    2018-02-01

    Full Text Available Miftāhul ‘Ulūm, written by al-Sakākī, especially the third part, was the beginning of a new phase in the development of Arabic rhetoric. Al-Sakākī divided the rhetoric into three fields of study, which are  (1 Ma’ānī, (2 Bayān, (3 Badī’. However, his style is influenced by philosophers, theologians and their verbal lexicon, which are difficult to take, especially for the ordinary recipient. Al-Sakākī described that his book containing several types of literature, namely, ‘ilm ṣarf in complete version and its conclusion, derivation science, and the grammatical study in the completeness of Ma’ānī and Bayān. The meaning of Makna is the study of completeness and conclusion. Therefore, books and prose, and poem require al-‘Arūḍ and al-Qawāfī include Ṣarf, Grammar, Ma’ānī, Bayān, limitation, reasoning, al’Arūḍ, and al-Qawāfī. He argued that the fields of study were influential in delivering knowledge to the student in order to reach the goal of the author towards his book.This research was an analytical descriptive study of al-Sakākī rhetoric that focused on the normative aspect represented by rhetorical rule and aesthetic aspects. Those aspects were shown by the feeling. Al-Sakākī rhetoric thought is a method based on mental division and has conducted in the construction of many factors, which the most important of them are philosophy and logic. Keywords: thought, rhetoric, meanings, sakkaki, study

  18. A study on wear resistance and microcrack of the Ti3Al/TiAl + TiC ceramic layer deposited by laser cladding on Ti-6Al-4V alloy

    International Nuclear Information System (INIS)

    Li Jianing; Chen Chuanzhong; Squartini, Tiziano; He Qingshan

    2010-01-01

    Laser cladding of the Al + TiC alloy powder on Ti-6Al-4V alloy can form the Ti 3 Al/TiAl + TiC ceramic layer. In this study, TiC particle-dispersed Ti 3 Al/TiAl matrix ceramic layer on the Ti-6Al-4V alloy by laser cladding has been researched by means of X-ray diffraction, scanning electron microscope, electron probe micro-analyzer, energy dispersive spectrometer. The main difference from the earlier reports is that Ti 3 Al/TiAl has been chosen as the matrix of the composite coating. The wear resistance of the Al + 30 wt.% TiC and the Al + 40 wt.% TiC cladding layer was approximately 2 times greater than that of the Ti-6Al-4V substrate due to the reinforcement of the Ti 3 Al/TiAl + TiC hard phases. However, when the TiC mass percent was above 40 wt.%, the thermal stress value was greater than the materials yield strength limit in the ceramic layer, the microcrack was present and its wear resistance decreased.

  19. Study of the 27Al(n,2,)26Al reaction via accelerator mass spectrometry

    International Nuclear Information System (INIS)

    Wallner, A.

    2000-06-01

    The excitation function for the 27 Al(n,2n) 26 Al reaction is expected to show a strongly non-linear behavior in the neutron-energy region around 14 MeV, the neutron energy in D-T plasmas; thus the production rate of 26 Al (t 1/2 =7.2*10 5 a) in D-T fusion environments can in principle be used to measure the temperature of such plasmas. Existing measurements, however, are strongly discordant. Therefore, a new accurate measurement of the 27 Al(n,2n) 26 Al cross sections in the near threshold region (E n =13.5-14.8 MeV) was performed with the goal to achieve relative cross sections with the highest accuracy possible. In addition, the measurements were also designed to provide good absolute cross-section values, as absolute cross sections are important for radioactive waste predictions. Samples of Al metal were irradiated with neutrons in the energy range near threshold (E th =13.55 MeV) at the Radiuminstitutes of both Vienna and St. Petersburg, and in Tokai-mura, Japan. In Tuebingen irradiations with neutrons of higher energies (17 and 19 MeV) were performed. The amount of 26 Al produced during the irradiations was measured via accelerator mass spectrometry (AMS) at the Vienna Environmental Research Accelerator (VERA). This work represents the first 26 Al measurements for this new facility. With this system, a background as low as 3*10 -15 for 26 Al/ 27 Al isotope ratios was obtained, corresponding to a (n,2n) cross section of 0.04 mb. Utilizing AMS, cross sections with much higher precision and considerably closer to the threshold than in previous investigations could be measured. The prerequisite for its application as a temperature monitor, namely a very well known shape of the excitation function was met. A quantitative prediction of the sensitivity of this method for monitoring the temperature in a D-T fusion plasma was therefore possible. For thermal plasmas temperature changes in the order of 5 to 15 % should be detectable. An even higher sensitivity was found

  20. Magnetostrictive properties of FeAl/polyester and FeAl/silicone composites

    Energy Technology Data Exchange (ETDEWEB)

    Riesgo, G. [Dpto. de Ciencias y Técnicas de la Navegación, Universidad de Oviedo, Campus universitario de Gijón, 33203 Gijón (Spain); Carrizo, J. [Dpto. de Física de la Universidad de Oviedo, c/ Calvo Sotelo s/n, 33007 Oviedo (Spain); Elbaile, L., E-mail: elbaile@uniovi.es [Dpto. de Física de la Universidad de Oviedo, c/ Calvo Sotelo s/n, 33007 Oviedo (Spain); Crespo, R.D. [Dpto. de Física de la Universidad de Oviedo, c/ Calvo Sotelo s/n, 33007 Oviedo (Spain); Sepúlveda, R. [Dpto. de Ingeniería Mecánica y de los Materiales, Universidad de Sevilla, Isla Cartuja, 41092 Sevilla (Spain); García, J.A. [Dpto. de Física de la Universidad de Oviedo, c/ Calvo Sotelo s/n, 33007 Oviedo (Spain)

    2017-01-15

    Highlights: • Nanocrystalline powders of FeAl have been obtained from the Fe{sub 81}Al{sub 19} ribbon produced by melt spinning. • The method allows the obtainment of a FeAl solid solution from the starting process. • The microstructure and magnetic properties of the powders were investigated. • Composites with a magnetostriction of 45 ppm have been obtained. - Abstract: Ribbons of composition Fe{sub 81}Al{sub 19} obtained by the melt spinning method have been used to yield powder by mechanical milling. Using this method, a rapid nanocrystallization and a FeAl solid solution phase was obtained from the start of the process. The microstructural and magnetic properties as well as the XRD patterns of the powders were studied in function of the milling time. Grain refinement and an increase of the coercive field were the main transformations resulting from increasing the milling time. Two sets of magnetostrictive composites were produced from the 100 h-milled powder. In one of them polyester was used as matrix and in the other one silicone. In the case of the silicone composites cured in a magnetic field of 140 mT in the longitudinal direction a saturation magnetostriction as high as 45 ppm was obtained.

  1. Construcción de celdas calorimétricas metálicas con escudos adiabáticos

    Directory of Open Access Journals (Sweden)

    Carlos A. Ruiz

    2010-07-01

    Full Text Available Se discuten los criterios de diseño y la caracterización térmica de ccldiis calorimétricas construidas en cobre dorado y aluminio, que son acopladas a un calorímetro de inmersión para el estudio de mojado de sólidos porosos. Los resultados muestran que las celdas metálicas presentan constantes fugas térmicas y tiempos de equilibrio menores que los hallados en las celdas de vidrios tradicionales tipo Dewar. Los mejores resultados se obtiene con la celda de aluminio provista de escudos adiabáticos flotantes, construidos en lámina del mismo material, con valores de constantes de fugas tcrinicas del orden de 3,5 * 10 ' min" ' y tiempos de equilibrio de solamente 8 minutos. La instalación calorimétrica completa se calibra secundariamente, con la determinación del calor de mezcla del sistema benccnociclohcxano; los resultados están en buen acuerdo con los registrados en la literatura.

  2. Thermodynamic calculation of Al-Gd and Al-Gd-Mg phase equilibria checked by key experiments

    International Nuclear Information System (INIS)

    Groebner, J.; Kevorkov, D.; Schmid-Fetzer, R.

    2001-01-01

    The binary Al-Gd and the ternary Al-Gd-Mg systems were calculated using the Calphad method. It is demonstrated that previous interpretation of ternary liquidus temperatures below 700 C must be related to other phase equilibria. The actual ternary liquidus temperatures are much higher, up to some 600 C above the previous interpretation in literature. They are widely governed by the high-melting compounds Al 2 Gd and Al 3 Gd with liquidus surfaces stretching far into the ternary system. A small number of key experiments in this work confirmed the calculated liquidus temperature and the phase relations. The available experimental data in literature fit excellently with the calculation in the binary Al-Gd system. In the ternary Al-Gd-Mg system, which is shown in several sections of the phase diagram, a good agreement can be observed too, considering the necessary reinterpretation of the liquidus temperatures suggested by Rokhlin et al. Ternary solubilities were not found experimentally. The ternary compound Al 4 GdMg (τ) forms in a ternary peritectic reaction at 761 C. (orig.)

  3. Forged HITEMAL: Al-based MMCs strengthened with nanometric thick Al{sub 2}O{sub 3} skeleton

    Energy Technology Data Exchange (ETDEWEB)

    Balog, Martin, E-mail: ummsbama@savba.sk [Institute of Materials and Machine Mechanics, Slovak Academy of Sciences, Racianska 75, 83102 Bratislava (Slovakia); Krizik, Peter; Nosko, Martin; Hajovska, Zuzana [Institute of Materials and Machine Mechanics, Slovak Academy of Sciences, Racianska 75, 83102 Bratislava (Slovakia); Victoria Castro Riglos, Maria [Centro Atómico Bariloche, Av. Bustillo 9.500, 8400 Bariloche, Río Negro (Argentina); Rajner, Walter [New Materials Development GmbH, Römerstrasse 28, 83410 Laufen, Leobendorf (Germany); Liu, De-Shin [National Chung Cheng University, 168 University Rd., Min-Hsiung, 62102 Chia-Yi, Taiwan (China); Simancik, Frantisek [Institute of Materials and Machine Mechanics, Slovak Academy of Sciences, Racianska 75, 83102 Bratislava (Slovakia)

    2014-09-08

    Bulk Al–Al{sub 2}O{sub 3} metal matrix composites (MMCs) named HITEMAL (high temperature aluminum) were fabricated in situ by forging compaction of five different types of gas-atomized commercial purity Al powders with a mean particle size in the range of 1–9 µm. As-forged HITEMAL consisted of (sub)micrometric Al grains (matrix) decorated with nanometric thick amorphous Al{sub 2}O{sub 3} (a-Al{sub 2}O{sub 3}) skeleton. Low-angle grain boundaries (LAGBs) free of Al{sub 2}O{sub 3} were located in the Al grain interior. The Al grain size and the portion of LAGBs increased with the increase in the relative powder surface area. As-forged HITEMAL shows excellent thermal stability up to 400 °C for 24 h. Annealing at temperatures ≥450 °C led to crystallization and morphological transformation from a-Al{sub 2}O{sub 3} skeleton to nanometric γ-Al{sub 2}O{sub 3} particles. Owing to the pinning effect of Al{sub 2}O{sub 3} phase, no Al grain growth took place during annealing up to 500 °C. HITEMAL showed attractive mechanical properties especially when tested at 300 °C (yield strength up to 220 MPa, Young's modulus up to 58 GPa). Despite the presence of a nearly continuous a-Al{sub 2}O{sub 3} skeleton along adjacent Al grains, forged HITEMAL materials had reasonable room temperature elongation of 7–26%. HITEMAL's elongation decreased as the Al grain size decreased and with increased testing temperature. The loss in elongation (uniform and total) was attributed to the inhomogeneous flow, which occurred due to high densities of high angle grain boundaries (dislocation sinks) and small content of LAGBs. The strength of HITEMAL stemmed from grain boundary mediated strengthening mechanisms. The results showed a positive deviation from the Hall–Petch plot, which is typical behavior of ultrafine-grained metals. Transformation of a-Al{sub 2}O{sub 3} skeleton to γ-Al{sub 2}O{sub 3} particles led to deterioration of the HITEMAL strength and Young's modulus.

  4. Determination of Al concentration in Al doped ZnO using Auger spectra excited by Mo X-rays

    International Nuclear Information System (INIS)

    Toth, J.; Koever, L.; Cserny, I.; Varga, D.

    2006-01-01

    Complete text of publication follows. A good conductor with excellent transparency is of crucial importance for the window layer of CIGS solar cells. Al doped ZnO is a good candidate for this purpose, its conductivity depends on the concentration and chemical state of the Al dopant atoms. It was demonstrated that the non-conventional XPS using Mo X-rays for excitation is a very sensitive tool for the detection of Al, P, Si [1, 2, 3]. The present paper compares the experimental ratios for Zn/Al photoinduced peak intensity ratios obtained using both Al and Mo X-ray excitations. The Mo excited Zn/Al intensity ratios can be determined with higher selectivity and sensitivity than the Zn/Al intensity ratios excited by Al X-rays. The experiments were performed with a hemispherical deflector electron spectrometer [4]. The chemical state of the Al was identified to be close to that in Al 2 O 3 . The atomic concentrations were determined using a calibration curve based on ZnO/Al samples with known composition of Al. The energy dependent efficiency of the electron spectrometer was determined comparing REELS spectra of Cu specimen to standard spectra measured by K. Goto (Nagoya Institute of Technology, Japan). For evaluation of the Al atomic concentrations from the measured photoelectron intensities the photoionisation cross-sections of Band et al [5] and the IMFP data of S. Tanuma et al [6] and C.J. Powell and A. Jablonski [7] were used. (author)

  5. Experimental evidences for reducing Mg activation energy in high Al-content AlGaN alloy by MgGa δ doping in (AlN)m/(GaN)n superlattice

    Science.gov (United States)

    Wang, Xiao; Wang, Wei; Wang, Jingli; Wu, Hao; Liu, Chang

    2017-03-01

    P-type doping in high Al-content AlGaN alloys is a main challenge for realizing AlGaN-based deep ultraviolet optoelectronics devices. According to the first-principles calculations, Mg activation energy may be reduced so that a high hole concentration can be obtained by introducing nanoscale (AlN)5/(GaN)1 superlattice (SL) in Al0.83Ga0.17N disorder alloy. In this work, experimental evidences were achieved by analyzing Mg doped high Al-content AlGaN alloys and Mg doped AlGaN SLs as well as MgGa δ doped AlGaN SLs. Mg acceptor activation energy was significantly reduced from 0.378 to 0.331 eV by using MgGa δ doping in SLs instead of traditional doping in alloys. This new process was confirmed to be able to realize high p-type doping in high Al-content AlGaN.

  6. Al-Shebab: An Al-Qaeda Affiliate Case Study (2Rev)

    Science.gov (United States)

    2017-10-01

    deputies responsible for finance , administration, and security. Coordination among regional groups is common.10 The deputy leader of al-Shebab, Mukhtar...Maaliya (Ministry of Finance ) controlled taxation. A complex court system also emerged. Multiple training camps were built that focused on hand-to-hand...Nathan Chandler, Counterterrorism and Counterinsurgency in Somalia: Assessing the Campaign Against Al Shabaab, Rand Corporation , 2016, accessed 6/5

  7. Experimental evidences for reducing Mg activation energy in high Al-content AlGaN alloy by MgGa δ doping in (AlN)m/(GaN)n superlattice

    OpenAIRE

    Xiao Wang; Wei Wang; Jingli Wang; Hao Wu; Chang Liu

    2017-01-01

    P-type doping in high Al-content AlGaN alloys is a main challenge for realizing AlGaN-based deep ultraviolet optoelectronics devices. According to the first-principles calculations, Mg activation energy may be reduced so that a high hole concentration can be obtained by introducing nanoscale (AlN)5/(GaN)1 superlattice (SL) in Al0.83Ga0.17N disorder alloy. In this work, experimental evidences were achieved by analyzing Mg doped high Al-content AlGaN alloys and Mg doped AlGaN SLs as well as MgG...

  8. Tadris Al Mufradat Li Tathbiq Maharah Al Kalam Fi Madrasah Al Muallimin Al Islamiyyah Li Mahad Bait Al Arqam Balong Jember

    Directory of Open Access Journals (Sweden)

    Muhammad Ardy Zaini

    2017-06-01

    Full Text Available There are four  skills in teaching Arabic. Ie listening, speaking, reading, and writing. Among these four, speaking considered one of the most important objectives of learning foreign language. In order to speak properly, one must know the vocabulary and apply it in a sentence. The aims of this research is to describe the teaching of vocabulary to apply the speaking skill in the school of Islamic teachers in the Institute of Bait al Arqom Balong Jember. This study used qualitative approach. The data collection was taken trough observation, personal interview, history and documentation. The teaching of vocabulary to apply the speaking skill at the Islamic Teachers' School at the Institute of Bait Al Arqam Balong Jember has gone well in terms of planning (general objectives and specific objectives, implementation (materials, use of the teaching method and teaching aids, and evaluation (assessment and evaluation. This teaching is to apply the speaking skill in terms of conversation or dialogue and lecture.

  9. NEK1 genetic variability in a Belgian cohort of ALS and ALS-FTD patients.

    Science.gov (United States)

    Nguyen, Hung Phuoc; Van Mossevelde, Sara; Dillen, Lubina; De Bleecker, Jan L; Moisse, Matthieu; Van Damme, Philip; Van Broeckhoven, Christine; van der Zee, Julie

    2018-01-01

    We evaluated the genetic impact of the amyotrophic lateral sclerosis (ALS) risk gene never in mitosis gene a-related kinase 1 (NEK1) in a Belgian cohort of 278 patients with ALS (n = 245) or ALS with frontotemporal dementia (ALS-FTD, n = 33) and 609 control individuals. We identified 2 ALS patients carrying a loss-of-function (LOF) mutation, p.Leu854Tyrfs*2 and p.Tyr871Valfs*17, that was absent in the control group. A third LOF variant p.Ser1036* was present in 2 sibs with familial ALS but also in an unrelated control person. Missense variants were common in both patients (3.6%) and controls (3.0%). The missense variant, p.Arg261His, which was previously associated with ALS risk, was detected with a minor allele frequency of 0.90% in patients compared to 0.33% in controls. Taken together, NEK1 LOF variants accounted for 1.1% of patients, although interpretation of pathogenicity and penetrance is complicated by the observation of occasional LOF variants in unaffected individuals (0.16%). Furthermore, enrichment of additional ALS gene mutations was observed in NEK1 carriers, suggestive of a "second hit" model were NEK1 variants may modify disease presentation of driving mutations. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  10. The effect of ammonia flow in the AlN spacer on the electrical properties of InAlN/AlN/GaN HEMT structures

    International Nuclear Information System (INIS)

    Gamarra, Piero; Lacam, Cedric; Magis, Michelle; Tordjman, Maurice; Di Forte Poisson, Marie-Antoinette

    2012-01-01

    During the past few years it has been reported that a thin AlN spacer of few nanometers needs to be inserted in InAlN/GaN high electron mobility transistors (HEMTs) to obtain high 2DEG carrier mobility. This work presents a systematic study of the effects of varying the ammonia flow in the AlN spacer of InAlN/AlN/GaN HEMTs grown by low pressure metalorganic vapour phase epitaxy (LP-MOVPE). The strain state, the surface roughness and the growth rate of AlN were found to be dependent on the V/III ratio. In addition the ammonia flow in the interlayer has a strong impact on the structural properties of the subsequent InAlN barrier layer and on the electrical properties of the structure. A sheet resistance as low as 327 Ω/□ with a sheet carrier density of 1.5 x 10 13 cm -2 has been obtained at room temperature. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. The effect of ammonia flow in the AlN spacer on the electrical properties of InAlN/AlN/GaN HEMT structures

    Energy Technology Data Exchange (ETDEWEB)

    Gamarra, Piero; Lacam, Cedric; Magis, Michelle; Tordjman, Maurice; Di Forte Poisson, Marie-Antoinette [III-V Lab., Marcussis (France)

    2012-01-15

    During the past few years it has been reported that a thin AlN spacer of few nanometers needs to be inserted in InAlN/GaN high electron mobility transistors (HEMTs) to obtain high 2DEG carrier mobility. This work presents a systematic study of the effects of varying the ammonia flow in the AlN spacer of InAlN/AlN/GaN HEMTs grown by low pressure metalorganic vapour phase epitaxy (LP-MOVPE). The strain state, the surface roughness and the growth rate of AlN were found to be dependent on the V/III ratio. In addition the ammonia flow in the interlayer has a strong impact on the structural properties of the subsequent InAlN barrier layer and on the electrical properties of the structure.istance as low as 327 {omega}/{open_square} with a sheet carrier density of 1.5 x 10{sup 13} cm{sup -2} has been obtained at room temperature. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Assessment of phase constitution on the Al-rich region of rapidly solidified Al-Co-Fe-Cr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, W., E-mail: witorw@gmail.com [Programa de Pós-Graduação em Ciência e Engenharia de Materiais, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, 13565-905 São Carlos, SP (Brazil); Bolfarini, C., E-mail: cbolfa@ufscar.br [Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, 13565-905 São Carlos, SP (Brazil); Kiminami, C.S., E-mail: kiminami@ufscar.br [Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, 13565-905 São Carlos, SP (Brazil); Botta, W.J., E-mail: wjbotta@ufscar.br [Departamento de Engenharia de Materiais, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, 13565-905 São Carlos, SP (Brazil)

    2016-12-15

    The formation of quasicrystalline approximants in rapidly solidified Al-Co-Fe-Cr alloys was investigated. Alloys of atomic composition Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8}, Al{sub 77}Co{sub 11}Fe{sub 6}Cr{sub 6} and Al{sub 76}Co{sub 19}Fe{sub 4}Cr{sub 1} were produced using melt spinning and arc melting methods and their microstructural characterization was carried out by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Up to the present there is no consensus in the literature regarding the formation of quasicrystalline phase or quasicrystalline approximants in the Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8} alloy. This work presents, for the first time, a detailed structural characterization of selected alloys in the Al-Co-Fe-Cr system close to the atomic composition Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8}. The results indicated the samples to be composed, mostly, by two intermetallic phases, which are quaternary extensions of Al{sub 5}Co{sub 2} and Al{sub 13}Co{sub 4} and are quasicrystalline approximants. Although the Al{sub 5}Co{sub 2} phase has already been reported in the Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8} alloy, the presence of the monoclinic Al{sub 13}Co{sub 4} is now identified for the first time in the as cast state. In the binary Al-Co system a quasicrystalline phase is known to form in a rapidly solidified alloy with composition close to the monoclinic and orthorhombic Al{sub 13}Co{sub 4} phases. This binary quasicrystalline phase presents an average valence electron per atom (e/a) between 1.7 and 1.9; thus, in addition to the Al{sub 71}Co{sub 13}Fe{sub 8}Cr{sub 8} alloy, the compositions Al{sub 77}Co{sub 11}Fe{sub 6}Cr{sub 6} and Al{sub 76}Co{sub 19}Fe{sub 4}Cr{sub 1} were chosen to be within the region of formation of the quaternary extension of the Al{sub 13}Co{sub 4} phase and also within the (e/a) of 1.7 to 1.9. However, no quasicrystalline phase is present in any of the studied alloys. The Al-Co-Fe-Cr system

  13. Corrosion analysis of AlMg2 and AlMgSi using electrochemical method

    International Nuclear Information System (INIS)

    Dian A; Maman Kartaman; Rosika K; Yanlinastuti

    2014-01-01

    Corrosion test of cladding materials and structures of research reactor fuel, AlMgSi and AlMg2 have been performed in demineralized water of pH 2 and 6.7 using an electrochemical method. Corrosion phenomenon is affected by several factor such as composition and condition of solution. The purpose of this activity is to investigate the corrosion phenomena through the determination of the parameters of corrosion and polarization curve. The materials used are AlMg2 and AlMgSi alloy in circular dish shape with an area of 1 Cm"2. Preparation of the test sample is performed through several stages polishing, cleaning and drying procedures followed ASTM G3. The electrochemical method is done by measuring the open circuit potential (OCP), polarization resistance and potentiodynamic in demineralized water of pH 2 and pH 6.7 at temperature of 25°C. The results of the OCP is the corrosion potential (Ecorr) of AlMg2 and AlMgSi each of -906.1 mV and -619.8 mV at pH 2 and -868.6 and -756.7 mV at pH 6.7 mV. The results of measurements by polarization resistance technique showed that the corrosion rate of AlMg2 and AlMgSi in safe category (<2 mpy) at pH 6.7 and at pH 2 corrosion rate increased significantly, but still in the lightweight category (<20 mpy). Potentiodynamic curves showed that the passivation at pH 6.7 is very low while the passivation at pH 2 occurs within a relatively short range potential and followed events corroded. (author)

  14. Aluminium polychloride in the groundwater potabilization process. Its performance as a coagulant in the aluminium chemistry domain; Policloruro de aluminio en el proceso de potabilizacion de aguas superficiales. Su comportamiento como coagulante dentro del ambito de la quimica del aluminio

    Energy Technology Data Exchange (ETDEWEB)

    Torra, A.; Valero, F. [Aigues Ter Llobregat. ATLL. Barcelona (Spain); Bisbal, J.L.; Tous, J.F. [Kemira Iberica. Barcelona (Spain)

    1998-12-01

    The development of prepolymerized coagulants of metallic salts, such as aluminium polychloride, has led to an improvement in the coagulation of drinking water and sewage, in front of the so-called hydrolyzed coagulants, such alum or ferric chloride. This paper describes the chemical properties and the advantages of the aforementioned coagulants: purification efficiency, working pH range, sensitivity to low temperatures, sludge filterability and residual Al. As a practical case it is described its application in the purification of surface waters of Llobregat river in Abrera (Barcelona). (Author) 32 refs.

  15. Catalytic effect of Al and AlN interlayer on the growth and properties of containing carbon films

    International Nuclear Information System (INIS)

    Zhou, Bing; Liu, Zhubo; Tang, Bin; Rogachev, A.V.

    2015-01-01

    Highlights: • DLC and CN x bilayers with Al (AlN) interlayer were fabricated by cathode arc technique. • Complete diffusion of Al and C atoms occurs at the interface of Al/DLC (CN x ) bilayer. • Al/CN x bilayer presents a higher content of Csp 3 /Csp 2 bonds. • The hardness of Al/DLC bilayer decreases but increases for the other bilayers. • Morphology of the bilayers was explained by growth mechanism of DLC and surface state of substrate. - Abstract: Diamond-like carbon (DLC) and carbon nitride (CN x ) bilayer films with Al and AlN interlayer were fabricated by pulse cathode arc technique. The structure, composition, morphology and mechanical properties of the films were investigated by Raman, Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), Knoop sclerometer and surface profilometer. The results indicated that the complete diffusion between C and Al atoms occurs in the Al/DLC and Al/CN x bilayer. Al interlayer induces the increase of the size and ordering of Csp 2 clusters in the films but AlN interlayer increases the disordering degree of Csp 2 clusters. XPS results showed that a higher content of Csp 3 /Csp 2 bonds presents in the Al/CN x bilayer, and Al and AlN interlayer decreases the atomic ratio of N/C. AFM with phase contrast mode illustrated the morphologic characteristics of the bilayer films. All the bilayers show a nano-structural surface. The morphology changes of the bilayer were well explained by the surface state of the substrate and the growth mechanism of DLC films. The hardness of Al/DLC bilayer decreases but it increases for the other bilayers compared to the corresponding DLC (CN x ) monolayer. The internal stress of the bilayer is significantly lower than that of the monolayer except for the AlN/CN x bilayer. These studies could make the difference at the time of choosing a suitable functional film for certain application

  16. Characteristics in AlN/AlGaN/GaN Multilayer-Structured High-Electron-Mobility Transistors

    International Nuclear Information System (INIS)

    Gui-Zhou, Hu; Ling, Yang; Li-Yuan, Yang; Si, Quan; Shou-Gao, Jiang; Ji-Gang, Ma; Xiao-Hua, Ma; Yue, Hao

    2010-01-01

    A new multilayer-structured AlN/AlGaN/GaN heterostructure high-electron-mobility transistor (HEMT) is demonstrated. The AlN/AlGaN/GaN HEMT exhibits the maximum drain current density of 800 mA/mm and the maximum extrinsic transconductance of 170 mS/mm. Due to the increase of the distance between the gate and the two-dimensional electron-gas channel, the threshold voltage shifts slightly to the negative. The reduced drain current collapse and higher breakdown voltage are observed on this AlN/AlGaN/GaN HEMT. The current gain cut-off frequency and the maximum frequency of oscillation are 18.5 GHz and 29.0 GHz, respectively. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  17. 60Co gamma radiation effect on AlGaN//AlN/GaN HEMT devices

    International Nuclear Information System (INIS)

    Wang Yanping; Luo Yinhong; Wang Wei; Zhang Keying; Guo Hongxia; Guo Xiaoqiang; Wang Yuanming

    2013-01-01

    The testing techniques and experimental methods of the 60 Co gamma irradiation effect on AlGaN/AlN/GaN high electron mobility transistors (HEMTs) are established. The degradation of the electrical properties of the device under the actual radiation environment are analyzed theoretically, and studies of the total dose effects of gamma radiation on AlGaN/AlN/GaN HEMTs at three different radiation bias conditions are carried out. The degradation patterns of the main parameters of the AlGaN/AlN/GaN HEMTs at different doses are then investigated, and the device parameters that were sensitive to the gamma radiation induced damage and the total dose level induced device damage are obtained. (authors)

  18. Cu-segregation at the Q'/α-Al interface in Al-Mg-Si-Cu alloy

    International Nuclear Information System (INIS)

    Matsuda, Kenji; Teguri, Daisuke; Uetani, Yasuhiro; Sato, Tatsuo; Ikeno, Susumu

    2002-01-01

    Cu segregation was detected at the Q ' /α-Al interface in an Al-Mg-Si-Cu alloy by energy-filtered transmission electron microscopy. By contrast, in a Cu-free Al-Mg-Si alloy no segregation was observed at the interface between the matrix and Type-C precipitate

  19. Effect of Al-5Ti-0.62C-0.2Ce Master Alloy on the Microstructure and Tensile Properties of Commercial Pure Al and Hypoeutectic Al-8Si Alloy

    Directory of Open Access Journals (Sweden)

    Wanwu Ding

    2017-06-01

    Full Text Available Al-5Ti-0.62C-0.2Ce master alloy was synthesized by a method of thermal explosion reaction in pure molten aluminum and used to modify commercial pure Al and hypoeutectic Al-8Si alloy. The microstructure and tensile properties of commercial pure Al and hypoeutectic Al-8Si alloy with different additions of Al-5Ti-0.62C-0.2Ce master alloy were investigated. The results show that the Al-5Ti-0.62C-0.2Ce alloy was composed of α-Al, granular TiC, lump-like TiAl3 and block-like Ti2Al20Ce. Al-5Ti-0.62C-0.2Ce master alloy (0.3 wt %, 5 min can significantly refine macro grains of commercial pure Al into tiny equiaxed grains. The Al-5Ti-0.62C-0.2Ce master alloy (0.3 wt %, 30 min still has a good refinement effect. The tensile strength and elongation of commercial pure Al modified by the Al-5Ti-0.62C-0.2Ce master alloy (0.3 wt %, 5 min increased by roughly 19.26% and 61.83%, respectively. Al-5Ti-0.62C-0.2Ce master alloy (1.5 wt %, 10 min can significantly refine both α-Al grains and eutectic Si of hypoeutectic Al-8Si alloy. The dendritic α-Al grains were significantly refined to tiny equiaxed grains. The morphology of the eutectic Si crystals was significantly refined from coarse needle-shape or lath-shape to short rod-like or grain-like eutectic Si. The tensile strength and elongation of hypoeutectic Al-8Si alloy modified by the Al-5Ti-0.62C-0.2Ce master alloy (1.5 wt %, 10 min increased by roughly 20.53% and 50%, respectively. The change in mechanical properties corresponds to evolution of the microstructure.

  20. Tailoring ultrafine grained and dispersion-strengthened Ti2AlC/TiAl ...

    Indian Academy of Sciences (India)

    and Ti-Al pre-alloyed powders at low temperature of 1150◦C. The composite mainly consisted ... Metal–matrix composites; mechanical properties; microstructures; sintering. 1. Introduction γ-TiAl-based intermetallic alloys have been extensively.

  1. Stagnation of the exploitation of Al ores and the depression of world prices of Al

    Directory of Open Access Journals (Sweden)

    Slavkovský Jozef

    1999-03-01

    Full Text Available In the contribution, data on Al – a metal of the 20th century are compiled together with the problems of genesis of the Al mineral raw ma-terials as well as types of bauxite and Al-laterite deposits. Furthermore, an overview of the world exploitation of bauxite during 1935-1980 is given along with the prognoses to 2000 and present situation (1992-1996. Overviews of the production of Al follows, providing its rela-tion to the bauxite exploitation. Contrary to the prognoses, a stabilization or stagnation has been observed in the exploitation of bauxite and production of Al during nineties, which a tendency is directly reflected in the world price of this commodity. When analyzing the Al prices for a longer period, some serious deviations can be noticed, that however presently represent a long-term minimum. We hope the stagnation of the production and the price decline are only temporary and new possibilities of the utilization of Al will be found soon.

  2. A study on preparation and hydriding of β-Mg2Al3 and γ-Mg17Al12

    International Nuclear Information System (INIS)

    Hadi Suwarno

    2009-01-01

    The mechanism of the synthetic formation of β-Mg 2 Al 3 and γ-Mg 17 Al 12 has been studied. Mechanical alloying of Mg and Al powders with the atomic ratio of Mg:Al = 2:3 in toluene solution yields β-Mg 2 Al 3 compound after milling for 30 h. The γ-Mg 17 Al 12 can be formed by heating the β-Mg 2 Al 3 at 430°C under high vacuum. The measured hydrogen capacities of β-Mg 2 Al 3 and γ-Mg 17 Al 12 as hydride at 300°C are 3.2 and 4.9 wt%, respectively. Microstructure of the Mg-Al specimen shows that on hydriding at 300°C the polygonal shape of the γ-Mg 17 Al 12 changes into irregular shapes which are composed of γ-MgH 2 and Al. (author)

  3. Marinbiologisk optegnelse i NUḪBAT AL-DAHR FĪ ʿAǦ ʾIB AL-BARR WA-AL-BAḤR

    OpenAIRE

    Provencal, Philippe

    2014-01-01

    I det arabiske geografiske værk NUḪBAT AL-DAHR FĪ ʿAǦ ʾIB AL-BARR WA-AL-BAḤR (færdigskrevet mellem 1324 og 1327) fra omtales seks dyr fra Adenbugten. Det dreje sig om savrokke, kuglefisk, pilrokke, pindsvinefisk og hvalhaj. Det sidste dyr har ikke kunnet bestemmes. Artiklen bringer en oversættelse af optegnelsen til engelsk samt både en filologisk som en biologisk kommentar. The aim of this article is to present a medieval Arabic report regarding sixanimals from the Gulf of Aden, to provid...

  4. MOSQUE ARCHITECTURE AS A SUSTAINABLE BUILDING IN URBAN (Case Study: Al Markas Al Islamic Mosque Makassar

    Directory of Open Access Journals (Sweden)

    Imriyanti Imriyanti

    2014-02-01

    Full Text Available Abstract Mosque Architecture is a part of Islamic architecture. Mosque should be fused with elements of nature because its function as a place to pray to God who created the universe. Al Markas Al Islamic Makassar mosque is used as a center of Islamic aspirations of the people and the government to accommodate all the activities of moslems in Makassar. Through this function, the provision of Al Markas Al Islamic mosque began from the desire of Islamic societies in Makassar, which wants the Islamic center to be equipped with facilities and infrastructure as well as architectural, monumental buildings and structures that can be last for hundreds of years (continuous, blend with the environment, and also can be used by the public. Having regard to the function of a mosque especially at the Al Markas Al Islamic Makassar mosque, then the problem that arise is how the Al Markas Al Islamic mosque can be survived/sustainable  in order  to function  as a place  of worship  and  as a center  of Islam.  This research  is a descriptive qualitative research that is trying to generate data in the form of systematic and accurate picture of the object of study. The sustaiprophetlity  of Al Markas AL Islamic mosque can be known through the concept of Islam  in accordance with the view of Islam as well as the sustaiprophetlity of the buildings that seen in the spatial pattern of the mosque, appearance, natural lighting, natural ventilation, and user behavior of the mosque. Keywords: mosque architecture, sustaiprophetlity, view of Islam     Abstrak Arsitektur masjid merupakan bagian dari arsitektur Islam. Bangunan masjid sebaiknya dapat menyatu dengan unsur alam karena masjid difungsikan sebagai wadah dalam bersujud/sembahyang  kepada Allah SWT yang menciptakan alam semesta ini. Masjid Al Markas Al Islamic Makassar merupakan kompleks kegiatan Islam yang digunakan sebagai pusat aspirasi masyarakat  dan pemerintahan  yang dapat menampung

  5. Adhesive and tribocorrosive behavior of TiAlPtN/TiAlN/TiAl multilayers sputtered coatings over CoCrMo

    Science.gov (United States)

    Canto, C. E.; Andrade, E.; Rocha, M. F.; Alemón, B.; Flores, M.

    2017-09-01

    The tribocorrosion resistance and adherence of multilayer coatings of TiAlPtN/TiAlN/TiAl synthesized by PVD reactive magnetron sputtering over a CoCrMo alloy substrate in 10 periods of 30 min each were analyzed and compared to those of the substrate alone and to that of a TiAlPtN single layer coating of the same thickness. The objective of the present work was to create multilayers with different amounts of Pt in order to enhance the tribocorrosion resistance of a biomedical alloy of CoCrMo. Tribocorrosion tests were performed using Simulated Body Fluid (SBF) at typical body temperature with a tribometer in a pin on disk test. The elemental composition and thickness of the coating which behave better at the tribocorrosion tests were evaluated by means of RBS (Rutherford Backscattering Spectroscopy) IBA (Ion Beam Analysis) technique, using an alpha particles beam of 1.8 MeV, before and after the reciprocating motion in the tribocorrosion test. In order to simulate the elemental profile of the samples, the SIMNRA simulation computer code was used. Measurements of the adhesion of the coatings to the substrate were carried on by means of a scratch test using a tribometer. By taking micrographs of the produced tracks, the critical loads at which the coatings are fully separated from the substrate were determined. From these tests it was observed that a coating with 10 min of TiAlPtN in a TiAlPtN/TiAl period of 30 min in multilayers of 10 periods and with an average thickness of 145 nm for the TiAlPtN nanolayers had the best tribocorrosion resistance behavior, compared to that of the CoCrMo alloy. The RBS experiments showed a reduction of the thickness of the films along with some loss of the multilayer structure after the reciprocating motion. The adhesion tests indicated that the multilayer with the average TiAlPtN thickness of 145 nm displayed the highest critical load. These results indicate a high correlation between the adherence and the tribocorrosion behavior.

  6. Microstructure of Reaction Zone Formed During Diffusion Bonding of TiAl with Ni/Al Multilayer

    Science.gov (United States)

    Simões, Sónia; Viana, Filomena; Koçak, Mustafa; Ramos, A. Sofia; Vieira, M. Teresa; Vieira, Manuel F.

    2012-05-01

    In this article, the characterization of the interfacial structure of diffusion bonding a TiAl alloy is presented. The joining surfaces were modified by Ni/Al reactive multilayer deposition as an alternative approach to conventional diffusion bonding. TiAl substrates were coated with alternated Ni and Al nanolayers. The nanolayers were deposited by dc magnetron sputtering with 14 nm of period (bilayer thickness). Joining experiments were performed at 900 °C for 30 and 60 min with a pressure of 5 MPa. Cross sections of the joints were prepared for characterization of their interfaces by scanning electron microscopy (SEM), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), high resolution TEM (HRTEM), energy dispersive x-ray spectroscopy (EDS), and electron backscatter diffraction (EBSD). Several intermetallic compounds form at the interface, assuring the bonding of the TiAl. The interface can be divided into three distinct zones: zone 1 exhibits elongated nanograins, very small equiaxed grains are observed in zone 2, while zone 3 has larger equiaxed grains. EBSD analysis reveals that zone 1 corresponds to the intermetallic Al2NiTi and AlNiTi, and zones 2 and 3 to NiAl.

  7. Al-quran dalam Perspektif Budaya

    OpenAIRE

    Sudrajat, Ajat

    2009-01-01

    Al-Quran merupakan kitab suci terakhir yang diturunkan kepada manusia. Tujuan utama diturunkannya al-Quran adalah sebagai kitab petunjuk yang meliputi bidang akidah, syariah, dan akhlak. Akan tetapi di luar ketiga petunjuk tersebut, al-Quran telah memberikan motivasi dan inspirasi kepada umat Islam dalam berbagai bidang kehidupan sehingga melahirkan jenis budaya tertentu. Dialog intelektual yang dilakukan secara kreatif oleh umat Islam terhadap al-Quran ternyata telah menghasilkan lahirnya ge...

  8. ITIJAHAT KAUN AL-NABI WA AL-RASUL FI SYAKHSIYAH MUHAMMAD FI NATSR MAULID AL-BARZANJI

    Directory of Open Access Journals (Sweden)

    Himmah Istomah

    2017-08-01

    Full Text Available One of human personalities is humanist. Based on the understanding of Maslow’s theory of motivation, researcher seeks to uncover kinds of motivational needs of Muhammad Saw contained in Maulid Al-Barzanjiy (the work of Ja 'far bin Hasan al-Barzanji (d. 1763 M. The goal is realized through a descriptive qualitative approach with  text analysis  about Psycholiterature of Endraswara. The results of this study indicate that in Maulid Al-Barzanji there are Muhammad Saw’s five needs and how their satisfying perfectly,  namely: physiological needs, safety, social, esteem, and self-actualization. Thus, it can be interpreted that Muhammad SAW as an ordinary human having motivational needs. His prophetic and apostleship honor is not a direct blessing from Allah, but he had been through some complicated processes in life. This can be applied by his followers, so they can complete their motivational needs to reach the satiation as a caliph and to be useful person in this world.

  9. Microstructure and bonding mechanism of Al/Ti bonded joint using Al-10Si-1Mg filler metal

    International Nuclear Information System (INIS)

    Sohn, Woong H.; Bong, Ha H.; Hong, Soon H.

    2003-01-01

    The microstructures and liquid state diffusion bonding mechanism of cp-Ti to 1050 Al using an Al-10.0wt.%Si-1.0wt.%Mg filler metal with 100 μm in thickness have been investigated at 620 deg. C under 1x10 -4 Torr. The effects of bonding process parameters on microstructure of bonded joint have been analyzed by using an optical microscope, AES, scanning electron microscopy and EDS. The interfacial bond strength of Al/Ti bonded joints was measured by the single lap shear test. The results show that the bonding at the interface between Al and filler metal proceeds by wetting the Al with molten filler metal, and followed by removal of oxide layer on surface of Al. The interface between Al and filler metal moved during the isothermal solidification of filler metal by the diffusion of Si from filler metal into Al layer. The interface between Al and filler metal became curved in shape with increasing bonding time due to capillary force at grain boundaries. The bonding at the interface between Ti and filler metal proceeds by the formation of two different intermetallic compound layers, identified as Al 5 Si 12 Ti 7 and Al 12 Si 3 Ti 5 , followed by the growth of the intermetallic compound layers. The interfacial bond strength at Al/Ti joint increased with increasing bonding time up to 25 min at 620 deg. C. However, the interfacial bond strength of Al/Ti joint decreased after bonding time of 25 min at 620 deg. C due to formation of cavities in Al near Al/intermetallic interfaces

  10. Micromechanisms of fracture and fatigue in Ti3Al based and TiAl based intermetallics

    International Nuclear Information System (INIS)

    James, A.W.; Chave, R.A.; Hippsley, C.A.; Bowen, P.

    1993-01-01

    Micromechanisms of fracture and fatigue crack growth resistance in specific Ti 3 Al based and TiAl based intermetallics are reviewed. Effects of test temperature, environment and microstructure on crack growth resistance are considered in detail for several Ti 3 Al and Ti'Al based intermetallic systems under development. The implications of these studies for the structural reliability of these materials is also addressed briefly. (orig.)

  11. Core electron binding energy shifts of AlBr3 and Al2Br6 vapor

    International Nuclear Information System (INIS)

    Mueller, Astrid M.; Plenge, Juergen; Leone, Stephen R.; Canton, Sophie E.; Rude, Bruce S.; Bozek, John D.

    2006-01-01

    The Al 2p and Br 3d inner-shell photoelectron spectra of aluminum tribromide monomer and dimer vapor were measured at 90 and 95 eV photon energy, respectively, to determine the core electron binding energies of the atoms in the two molecular species. While AlBr 3 has three identical Br atoms, Al 2 Br 6 exhibits four terminal and two bridging Br atoms. The species are identified by their distinct valence photoelectron spectra. Comparison of the observed Al 2p 1/2 and Al 2p 3/2 electron binding energies of AlBr 3 with those of Al 2 Br 6 shows that there is a chemical shift of (0.15 ± 0.03) eV to lower energy in the dimer. In Al 2 Br 6 , an assignment is proposed in which the Br 3d 3/2 and Br 3d 5/2 binding energies of terminal Br atoms are (1.18 ± 0.03) eV lower than those of bridging Br atoms. This assignment assumes that both types of Br atoms have similar cross-sections for ionization. With this result, the Br 3d 3/2 and Br 3d 5/2 binding energies of Br atoms in AlBr 3 are (0.81 ± 0.03) eV lower than those of bridging Br atoms of the dimer but (0.37 ± 0.03) eV higher than those of terminal Br atoms of the dimer. The obtained chemical shifts are considered in terms of the binding relations and electron density distributions in both molecules. Chemical shifts that are larger than a few hundred millielectron volts, as observed in the Al 2 Br 6 /AlBr 3 system, offer potential to study the dissociation dynamics of the dimer in a femtosecond visible or ultraviolet-pump/XUV-probe experiment

  12. PENDEKATAN HERMENEUTIK DALAM PEMAHAMAN HADIS (Kajian Kitab Fath al-Bari Karya Ibn Hajar Al-‘Asqalani

    Directory of Open Access Journals (Sweden)

    Agusni Yahya

    2014-12-01

    Full Text Available The hadith explanation book of Sahih al-Bukhari written by Ibn Hajar Al-‘Asqalani, Fath al-Bari, is one of the most pupular books in Moslem ummah. Is widely used by Moslem scholars to meet the meanings of hadiths compiled by the imam al-Bukhari in his Sahih al-Bukhari. Fath al-Bari is considered significant to do the research on it in order to develop the science of hadith, mainly through the hermeneutic method. By using this method, the research questions are: 1. How does Ibn Hajar Al-‘Asqalani explain the matans (hadith texts of Sahih al Bukhari in connection with hermeneutic method? 2. What are the hermeneutic principles used by Ibn Hajar Al-‘Asqalani in his explanations of hadith? This research is expected to respond the research questions above so that it can be implimented the field of hadith in relation to develop hadith methodology. Finally, the research uncover that in his explanations of hadiths,  Ibn Hajar Al-‘Asqalani is oriented his world views to the classical Islam, the era of Prophet’s companions and their successors, the Salaf al-Salih. He does not express the Islamic world issues available in his time in his explanations of the hadiths. He is considered a normative ‘ulama since he is not influenced by the emerging cases situated his time in Egypt, Mecca and Madina. He tends to be textual to explain the matans of hadiths although to some extent he uncovers the historical contexts of the hadiths he explains. This is common for a muhadith  whose main jobs is to collect and narrate the whole data on Prophet's sayings, acts and permissions either on sanads (narrators or matans (texts.Keywords:  Fath al-Bari; sharh al-hadith; hermeneutik.

  13. Thermophysical properties of αAl2O3, MgAl2O4 and AlN at low tempertures

    International Nuclear Information System (INIS)

    Burghartz, S.

    1995-12-01

    A possibility for producing energy in future might be the nuclear fusion. The process of nuclear fusion is characterized by melting nuclei of hydrogen atoms (deuterium and tritium) which yield to the production of helium atom nuclei. For this process extremely high temperatures of the deuterium-tritium-gas plasma are necessary. The additional heating of the plasma by microwaves requires materials with low diaelectric losses and high thermal conductivity. The thermal conductivity can be increased by cooling the windows which lead to the plasma chambre. Experimental investigations with the aim to check the influence of liquid nitrogen (T=70 K) on the cooling of the windows were performed in the temperature region 70 K 2 O 3 , MgAl 2 O 4 and AlN were measured. The thermal conductivity can be calculated using the equation λ=αc p ρ λ=thermal conductivity α=thermal diffusivity c p =specific heat (at constant pressure) ρ=density. Furthermore a theoretical method to calculate the thermal conductivity at low temperatures is presented; this is done by using a model modification of heat transport in electric insulators. As result the influence of intrinsic parameters (crystal structure, interatomar binding, anharmonicity) and extrinsic parameters (point defects, dislocations, boundary areas) upon thermal conductivity of α-Al 2 O 3 , MgAl 2 O 4 and AlN are achieved. (orig.)

  14. Grain refinement of Al wrought alloys with newly developed AlTiC master alloys; Kornfeinung von Al-Knetlegierungen mit neu entwickelten AlTiC-Vorlegierungen

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, W. [Vereinigte Aluminium-Werke AG, Bonn (Germany). Forschung und Entwicklung

    2000-10-01

    AlTiC master alloys are a new grain refiner type to produce an equiaxed grain structure of cast extrusion and rolling ingots. These master alloys contain Ti carbides which act as nucleants of the {alpha} solid solution during solidification. The TiC content is lower than the TiB{sub 2} content of the industrial proved AlTiB master alloys. Benefits of the AlTiC master alloys are the low agglomeration tendency of the Ti carbides in the melt and that no Zr poisoning takes place. Despite of the low Ti carbide content the grain refinement performance can be very efficient, if low melt temperatures during casting will be used and as result of this a sufficient constitutional supercooling at the solidification front is achieved. (orig.)

  15. Advanced life support (ALS) instructors experience of ALS education in Western Australia: a qualitative exploratory research study.

    Science.gov (United States)

    Taplin, John; McConigley, Ruth

    2015-04-01

    When cardiac arrest occurs, timely competent advanced life support (ALS) interventions by nursing staff can influence patient outcomes. Ongoing ALS education influences maintenance of competency and avoids skill decay. To explore the methods of ALS education delivery for nurses in the workplace; describe the issues relating to maintaining ALS competency; explore ALS competency decay for nurses and develop recommendations for the provision of continuing ALS education. A qualitative exploratory design was used to study ALS education provision in the workplace. Data were collected from ALS nurse experts in Western Australia by face-to-face and phone interviews. Semi-structured interviews were conducted and organised around a set of predetermined questions. Two major themes were identified; the first theme Demand and Supply describes the increasing demand for ALS education for nurses and the challenges with providing timely cost effective traditional face-to-face ALS education. The second theme, Choosing The Best Education Options describes new ways to provide ALS education using emerging technologies. The study suggested that using e-learning methods would assist with educating the maximum amount of nurses in a timely manner and e-learning and teleconferencing offer opportunities to reach nurses in distant locations. Delivering ALS education more frequently than annually would increase skills maintenance and lessen skill decay. Further research is required to explore which blended e-learning model is best suited to ALS education. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Al-Qaeda-Syria (AQS): An Al-Qaeda Affiliate Case Study

    Science.gov (United States)

    2017-10-01

    Special Operations/Low Intensity Conflict CT Counterterrorism FF Foreign Fighter FSA Free Syrian Army GEC Global Engagement Center HTS Hay’at...war as an opportunity for the global jihadist movement, an opportunity that paralleled the one Iraq had offered a decade earlier.11 He was initially...Zawahiri’s vision of Al-Qaeda franchises oriented toward winning popular support. When al-Zawahiri published his “General Guidelines for Jihad” in

  17. Mechanochemical synthesis of Cu-Al and methyl orange intercalated Cu-Al layered double hydroxides

    International Nuclear Information System (INIS)

    Qu, Jun; He, Xiaoman; Chen, Min; Hu, Huimin; Zhang, Qiwu; Liu, Xinzhong

    2017-01-01

    In this study, a mechanochemical route to synthesize a Cu-Al layered double hydroxide (LDH) and a methyl orange (MO) intercalated one (MO-LDH) was introduced, in which basic cupric carbonate (Cu_2(OH)_2CO_3) and aluminum hydroxide (Al(OH)_3) with Cu/Al molar ratio at 2/1 was first dry ground for 2 h and then agitated in water or methyl orange solution for another 4 h to obtain the LDH and MO-LDH products without any heating operation. The prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Thermogravimetry (TG), Differential scanning calorimetry (DSC) and Scanning electron microscopy (SEM). The products showed high crystallinity phase of Cu-Al and MO intercalated Cu-Al LDH with no evident impurities, proving that the craft introduced here was facile and effective. The new idea can be applied in other fields to produce organic-inorganic composites. - Highlights: • A facile mechanochemical route to synthesize Cu-Al and MO intercalated Cu-Al LDH. • The products possesses high crystalline of LDH phase with no impure phases. • The dry milling process induces the element substitution between the raw materials. • The agitation operation helps the grain growth of LDH.

  18. Mechanochemical synthesis of Cu-Al and methyl orange intercalated Cu-Al layered double hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Jun, E-mail: forsjun@whut.edu.cn [School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei 430070 (China); He, Xiaoman; Chen, Min; Hu, Huimin [School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei 430070 (China); Zhang, Qiwu, E-mail: zhangqw@whut.edu.cn [School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei 430070 (China); Liu, Xinzhong [College of Ecological Environment and Urban Construction, Fujian University of Technology, Fuzhou 350118 China (China)

    2017-04-15

    In this study, a mechanochemical route to synthesize a Cu-Al layered double hydroxide (LDH) and a methyl orange (MO) intercalated one (MO-LDH) was introduced, in which basic cupric carbonate (Cu{sub 2}(OH){sub 2}CO{sub 3}) and aluminum hydroxide (Al(OH){sub 3}) with Cu/Al molar ratio at 2/1 was first dry ground for 2 h and then agitated in water or methyl orange solution for another 4 h to obtain the LDH and MO-LDH products without any heating operation. The prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Thermogravimetry (TG), Differential scanning calorimetry (DSC) and Scanning electron microscopy (SEM). The products showed high crystallinity phase of Cu-Al and MO intercalated Cu-Al LDH with no evident impurities, proving that the craft introduced here was facile and effective. The new idea can be applied in other fields to produce organic-inorganic composites. - Highlights: • A facile mechanochemical route to synthesize Cu-Al and MO intercalated Cu-Al LDH. • The products possesses high crystalline of LDH phase with no impure phases. • The dry milling process induces the element substitution between the raw materials. • The agitation operation helps the grain growth of LDH.

  19. Superstructure formation in PrNi_2Al_3 and ErPd_2Al_3

    International Nuclear Information System (INIS)

    Eustermann, Fabian; Hoffmann, Rolf-Dieter; Janka, Oliver; Oldenburg Univ.

    2017-01-01

    The intermetallic phase ErPd_2Al_3 was obtained by arc-melting of the elements and subsequent annealing for crystal growth. The sample was studied by X-ray diffraction on powders and single crystals. The structure of ErPd_2Al_3 was refined from X-ray diffraction data and revealed a superstructure of PrNi_2Al_3 - a CaCu_5 derivative (P6/m, a=1414.3(1), c=418.87(3) pm wR=0.0820, 1060 F"2 values, 48 variables). The same superstructure was subsequently found for PrNi_2Al_3 (P6/m, a=1407.87(4), c=406.19(2) pm, wR=0.0499, 904 F"2 values, 47 variables). In the crystal structure, the aluminium and transition metal atoms form a polyanionic network according to [T_2Al_3]"δ"-, while rare earth atoms fill cavities within the networks. They are coordinated by six transition metal and twelve aluminum atoms. In contrast to the PrNi_2Al_3 type structure reported so far, two crystallographic independent rare-earth sites are found of which one (1b) is shifted by 1/2 z, causing a distortion in the structure along with a recoloring of the T and Al atoms in the network.

  20. Derecho humano al agua y al saneamiento: derechos estrechamente vinculados al derecho a la vida

    OpenAIRE

    Fernández Aller, Maria Celia; Luis Romero, Elena de; Guzmán Acha, Cristina

    2013-01-01

    Los derechos humanos al agua y al saneamiento están íntimamente relacionados con otros derechos esenciales para la vida, como la alimentación o la salud. Su reconocimiento como derechos humanos en 2010 marca un hito importante en el respeto, protección y realización de estos derechos, que se encuentran seriamente vulnerados para una mayoría de población más vulnerable y empobrecida, sobre todo en el ámbito rural. Mucho camino queda aún para conseguir no sólo la disponibilidad de agua y saneam...

  1. Deformation mechanisms of nanotwinned Al

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xinghang [Texas A & M Univ., College Station, TX (United States)

    2016-11-10

    The objective of this project is to investigate the role of different types of layer interfaces on the formation of high density stacking fault (SF) in Al in Al/fcc multilayers, and understand the corresponding deformation mechanisms of the films. Stacking faults or twins can be intentionally introduced (via growth) into certain fcc metals with low stacking fault energy (such as Cu, Ag and 330 stainless steels) to achieve high strength, high ductility, superior thermal stability and good electrical conductivity. However it is still a major challenge to synthesize these types of defects into metals with high stacking fault energy, such as Al. Although deformation twins have been observed in some nanocrystalline Al powders by low temperature, high strain rate cryomilling or in Al at the edge of crack tip or indentation (with the assistance of high stress intensity factor), these deformation techniques typically introduce twins sporadically and the control of deformation twin density in Al is still not feasible. This project is designed to test the following hypotheses: (1) Certain type of layer interfaces may assist the formation of SF in Al, (2) Al with high density SF may have deformation mechanisms drastically different from those of coarse-grained Al and nanotwinned Cu. To test these hypotheses, we have performed the following tasks: (i) Investigate the influence of layer interfaces, stresses and deposition parameters on the formation and density of SF in Al. (ii) Understand the role of SF on the deformation behavior of Al. In situ nanoindentation experiments will be performed to probe deformation mechanisms in Al. The major findings related to the formation mechanism of twins and mechanical behavior of nanotwinned metals include the followings: 1) Our studies show that nanotwins can be introduced into metals with high stacking fault energy, in drastic contrast to the general anticipation. 2) We show two strategies that can effectively introduce growth twins in

  2. Deformation mechanisms of nanotwinned Al

    International Nuclear Information System (INIS)

    Zhang, Xinghang

    2016-01-01

    The objective of this project is to investigate the role of different types of layer interfaces on the formation of high density stacking fault (SF) in Al in Al/fcc multilayers, and understand the corresponding deformation mechanisms of the films. Stacking faults or twins can be intentionally introduced (via growth) into certain fcc metals with low stacking fault energy (such as Cu, Ag and 330 stainless steels) to achieve high strength, high ductility, superior thermal stability and good electrical conductivity. However it is still a major challenge to synthesize these types of defects into metals with high stacking fault energy, such as Al. Although deformation twins have been observed in some nanocrystalline Al powders by low temperature, high strain rate cryomilling or in Al at the edge of crack tip or indentation (with the assistance of high stress intensity factor), these deformation techniques typically introduce twins sporadically and the control of deformation twin density in Al is still not feasible. This project is designed to test the following hypotheses: (1) Certain type of layer interfaces may assist the formation of SF in Al, (2) Al with high density SF may have deformation mechanisms drastically different from those of coarse-grained Al and nanotwinned Cu. To test these hypotheses, we have performed the following tasks: (i) Investigate the influence of layer interfaces, stresses and deposition parameters on the formation and density of SF in Al. (ii) Understand the role of SF on the deformation behavior of Al. In situ nanoindentation experiments will be performed to probe deformation mechanisms in Al. The major findings related to the formation mechanism of twins and mechanical behavior of nanotwinned metals include the followings: 1) Our studies show that nanotwins can be introduced into metals with high stacking fault energy, in drastic contrast to the general anticipation. 2) We show two strategies that can effectively introduce growth twins in

  3. Study on Microstructure and Mechanical Properties of Hypereutectic Al-18Si Alloy Modified with Al-3B.

    Science.gov (United States)

    Gong, Chunjie; Tu, Hao; Wu, Changjun; Wang, Jianhua; Su, Xuping

    2018-03-20

    An hypereutectic Al-18Si alloy was modified via an Al-3B master alloy. The effect of the added Al-3B and the modification temperature on the microstructure, tensile fracture morphologies, and mechanical properties of the alloy were investigated using an optical microscope, Image-Pro Plus 6.0, a scanning electron microscope, and a universal testing machine. The results show that the size of the primary Si and its fraction decreased at first, and then increased as an additional amount of Al-3B was added. When the added Al-3B reached 0.2 wt %, the fraction of the primary Si in the Al-18Si alloy decreased with an increase in temperature. Compared with the unmodified Al-18Si alloy, the tensile strength and elongation of the alloy modified at 850 °C with 0.2 wt % Al-3B increased by 25% and 81%, respectively. The tensile fracture of the modified Al-18Si alloy exhibited partial ductile fracture characteristics, but there were more areas with ductile characteristics compared with that of the unmodified Al-18Si alloy.

  4. 26Mg(p,n)26Al and 23Na(α,n)26Al reactions

    International Nuclear Information System (INIS)

    Skelton, R.T.

    1985-01-01

    Cross sections for the 26 Mg(p,n) 26 Al reaction were measured from threshold at 4.988 MeV to 5.820 MeV. Cross sections for the 23 Na(α,n) 26 Al reaction were measured from threshold at 3.483 MeV to 4.597 MeV. In each case, separate measurements were to the ground state and to the first and second excited states of 26 Al. Cross sections for the inverse reactions were calculated and reaction rate factors relating to the destruction of 26 Al in a supernova environment were determined. Astrophysical implications relating to the observation of live and extinct 26 Al are discussed. Excitation functions for several additional exit channels for the 26 Mg + rho and 23 Na + α reactions are reported

  5. effect of the parameters of AlN/GaN/AlGaN and AlN/GaN/InAlN heterostructures with a two-dimensional electron gas on their electrical properties and the characteristics of transistors on their basis

    Energy Technology Data Exchange (ETDEWEB)

    Tsatsulnikov, A. F., E-mail: andrew@beam.ioffe.ru [Russian Academy of Sciences, Submicron Heterostructures for Microelectronics Research and Engineering Center (Russian Federation); Lundin, V. W.; Zavarin, E. E.; Yagovkina, M. A.; Sakharov, A. V. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation); Usov, S. O. [Russian Academy of Sciences, Submicron Heterostructures for Microelectronics Research and Engineering Center (Russian Federation); Zemlyakov, V. E.; Egorkin, V. I. [National Research University of Electronic Technology (MIET) (Russian Federation); Bulashevich, K. A.; Karpov, S. Yu. [“Soft-Impact” Ltd. (Russian Federation); Ustinov, V. M. [Russian Academy of Sciences, Submicron Heterostructures for Microelectronics Research and Engineering Center (Russian Federation)

    2016-10-15

    The effect of the layer thickness and composition in AlGaN/AlN/GaN and InAlN/AlN/GaN transistor heterostructures with a two-dimensional electron gas on their electrical and the static parameters of test transistors fabricated from such heterostructures are experimentally and theoretically studied. It is shown that the use of an InAlN barrier layer instead of AlGaN results in a more than twofold increase in the carrier concentration in the channel, which leads to a corresponding increase in the saturation current. In situ dielectric-coating deposition on the InAlN/AlN/GaN heterostructure surface during growth process allows an increase in the maximum saturation current and breakdown voltages while retaining high transconductance.

  6. Fabrication and thermal characterization of amorphous and nanocrystalline Al{sub 9}FeNi/Al{sub 3}Ti compound

    Energy Technology Data Exchange (ETDEWEB)

    Tavoosi, Majid, E-mail: ma.tavoosi@gmail.com

    2017-01-15

    In this study, the fabrication and structural characterization of amorphous/nanocrystalline Al{sub 9}FeNi/Al{sub 3}Ti phase has been performed. In this regards, milling and annealing processes were applied on Al{sub 80}Fe{sub 10}Ti{sub 5}Ni{sub 5} (at. %) powder mixture for different periods of time. The prepared samples were characterized using X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM) and differential scanning calorimetery (DSC). According to the results, supersaturated solid solution, nanocrystalline Al{sub 9}FeNi/Al{sub 3}Ti (with average crystallite size of about 7 nm) and amorphous phases indicated three different microstructures which can be formed in Al{sub 80}Fe{sub 10}Ti{sub 5}Ni{sub 5} system during milling process. The formed supersaturated solid solution and amorphous phases were unstable and transformed to Al{sub 9}FeNi/Al{sub 3}Ti intermetallic compound during annealing process. It is shown that, Al{sub 9}FeNi phase in Al{sub 9}FeNi/Al{sub 3}Ti intermetallic compound can decompose into Al{sub 3}Ni, Al{sub 13}Fe{sub 4} and liquid phases during a reversible peritectic reaction at 809 °C. - Highlights: • We study the effect of milling process on Al{sub 80}Fe{sub 10}Ti{sub 5}Ni{sub 5} alloy. • We study the effect of annealing on Al{sub 80}Fe{sub 10}Ti{sub 5}Ni{sub 5} supersaturated solid solution phase. • We study the effect of annealing on Al{sub 80}Fe{sub 10}Ti{sub 5}Ni{sub 5} amorphous phase. • We study the thermal behaviour of Al{sub 9}FeNi/Al{sub 3}Ti compound.

  7. Computer aided cooling curve analysis for Al-5Si and Al-11Si alloys ...

    African Journals Online (AJOL)

    The effect of grain refiner, modifier, and combination of grain refiner cum modifier was studied on Al-5Si and Al-11Si alloys using computer aided cooling curve analysis. For combined grain refinement and modification effect, Al-Ti-B-Sr single master alloy was developed that acted as both grain refiner and modifier.

  8. AL-USRCRN Station Information

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Documentation of United States Alabama Regional Climate Reference Network (AL-USRCRN) installations in 2006. Installations documented are for AL-USRCRN pilot project...

  9. Gd3+-ESR and magnetic susceptibility of GdCu4Al8 and GdMn4Al8

    International Nuclear Information System (INIS)

    Coldea, R.; Coldea, M.; Pop, I.

    1994-01-01

    Gd ESR of GdCu 4 Al 8 and GdMn 4 Al 8 and magnetic susceptibility of GdCu 4 Al 8 , GdMn 4 Al 8 , and YMn 4 Al 8 were measured in the temperature range of 290K--460K and 90K--1050K, respectively. The occurrence of the Mn moment in YMn 4 Al 8 and GdMn 4 Al 8 is strongly correlated with the critical value of d∼2.6 angstrom of the Mn-Mn distance below which the Mn moment is not stable. The experimental data for GdMn 4 Al 8 , compared with the data for the isostructural compounds GdCu 4 Al 8 and YMn 4 Al 8 , show that near the critical value of d, the existence of Mn moment depends not only on the value of d, but also on the local magnetic surroundings. It has been revealed that the magnetic character of Mn moment in YMn 4 Al 8 and GdMn 4 Al 8 changes from an itinerant electron type to a local-moment type with increasing temperature

  10. Effect of AlB2-Mg interaction on the mechanical properties of Al-based composites

    International Nuclear Information System (INIS)

    Calderon, Hermes E.; Hidalgo, Ruth G.I.; Melgarejo, Z. Humberto; Suarez, O. Marcelo

    2010-01-01

    A series of Al-based composites with a matrix containing 2.5 wt.%Cu and 1 wt.%Mg, and reinforced with Al diborides was manufactured and characterized via microscopy and mechanical testing. The impact resistance of the composites revealed interaction between AlB 2 dispersoids and Mg originally present in the Al matrix. An unexpected increase in the absorbed impact energy of composites with diborides prompted complementary experiments leading to this finding. Hardness tests were correlated to those results and provided further evidence of the interaction between Mg and the dispersoids. Additional energy dispersive spectroscopy (EDS) analysis and X-ray diffraction tests supported with crystal modeling demonstrated that Mg effectively diffused into the AlB 2 crystal producing a doped structure with an Al 1-x Mg x B 2 formula where x lies between 0.08 and 0.15.

  11. Potential skin involvement in ALS: revisiting Charcot's observation - a review of skin abnormalities in ALS.

    Science.gov (United States)

    Paré, Bastien; Gros-Louis, François

    2017-07-26

    Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease affecting motor neurons of the brain and spinal cord, leading to progressive paralysis and death. Interestingly, many skin changes have been reported in ALS patients, but never as yet fully explained. These observations could be due to the common embryonic origin of the skin and neural tissue known as the ectodermal germ layer. Following the first observation in ALS patients' skin by Dr Charcot in the 19th century, in the absence of bedsores unlike other bedridden patients, other morphological and molecular changes have been observed. Thus, the skin could be of interest in the study of ALS and other neurodegenerative diseases. This review summarizes skin changes reported in the literature over the years and discusses about a novel in vitro ALS tissue-engineered skin model, derived from patients, for the study of ALS.

  12. Effects of O in a binary-phase TiAl-Ti3Al alloy: from site occupancy to interfacial energetics

    International Nuclear Information System (INIS)

    Wei Ye; Xu Huibin; Zhou Hongbo; Zhang Ying; Lu Guanghong

    2011-01-01

    We have investigated site occupancy and interfacial energetics of a TiAl-Ti 3 Al binary-phase system with O using a first-principles method. Oxygen is shown to energetically occupy the Ti-rich octahedral interstitial site, because O prefers to bond with Ti rather than Al. The occupancy tendency of O in TiAl alloy from high to low is α 2 -Ti 3 Al to the γ-α 2 interface and γ-TiAl. We demonstrate that O can largely affect the mechanical properties of the TiAl-Ti 3 Al system. Oxygen at the TiAl-Ti 3 Al interface reduces both the cleavage energy and the interface energy, and thus weakens the interface strength but strongly stabilizes the TiAl/Ti 3 Al interface with the O 2 molecule as a reference. Consequently, the mechanical property variation of TiAl alloy due to the presence of O not only depends on the number of TiAl/Ti 3 Al interfaces but also is related to the O concentration in the alloy.

  13. A study on wear resistance and microcrack of the Ti{sub 3}Al/TiAl + TiC ceramic layer deposited by laser cladding on Ti-6Al-4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Li Jianing, E-mail: ljnljn1022@163.com [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), Department of Materials Science, Shandong University, Jing Shi Road 17923, Jinan 250061, Shandong (China); Chen Chuanzhong [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Department of Materials Science, Shandong University, Jing Shi Road 17923, Jinan 250061, Shandong (China); Squartini, Tiziano [INFM-Department of Physics, Siena University, Siena 53100 (Italy); He Qingshan [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Department of Materials Science, Shandong University, Jing Shi Road 17923, Jinan 250061, Shandong (China)

    2010-12-15

    Laser cladding of the Al + TiC alloy powder on Ti-6Al-4V alloy can form the Ti{sub 3}Al/TiAl + TiC ceramic layer. In this study, TiC particle-dispersed Ti{sub 3}Al/TiAl matrix ceramic layer on the Ti-6Al-4V alloy by laser cladding has been researched by means of X-ray diffraction, scanning electron microscope, electron probe micro-analyzer, energy dispersive spectrometer. The main difference from the earlier reports is that Ti{sub 3}Al/TiAl has been chosen as the matrix of the composite coating. The wear resistance of the Al + 30 wt.% TiC and the Al + 40 wt.% TiC cladding layer was approximately 2 times greater than that of the Ti-6Al-4V substrate due to the reinforcement of the Ti{sub 3}Al/TiAl + TiC hard phases. However, when the TiC mass percent was above 40 wt.%, the thermal stress value was greater than the materials yield strength limit in the ceramic layer, the microcrack was present and its wear resistance decreased.

  14. Synthesis behavior of nanocrystalline Al-Al2O3 composite during low time mechanical milling process

    International Nuclear Information System (INIS)

    Alizadeh, Mostafa; Aliabadi, Morteza Mirzaei

    2011-01-01

    Research highlights: → In the low time milling the effect of Al 2 O 3 amount is investigated → Al 2 O 3 particles are distributed uniformly in the Al matrix → In the low time milling it is possible to produce nanostructured composite powder → Median size and bulk density measurements demonstrate reaching the steady state. - Abstract: In this work, four different volume fractions of Al 2 O 3 (10, 20, 30 and 40 vol.%) were mixed with the fine Al powder and the powder blends were milled for 5 h. Scanning electron microscopy analysis, particle size analysis and bulk density measurements were used to investigate the morphological changes and achieving the steady state conditions. The results showed that increasing the Al 2 O 3 content can provide the steady state particle size in 5 h milling process. It was found that increasing the volume fraction of Al 2 O 3 leads to increasing the uniformity of Al 2 O 3 . Standard deviations of microhardness measurements confirmed this result. The XRD pattern and XRF investigations depicted that increasing the Al 2 O 3 content causes an increase in the crystal defects, micro-strain and Fe contamination during 5 h milling process of nanocrystalline composite powders while the grain size is decreased. To investigate the effect of milling time, Al-30 vol.% Al 2 O 3 (which achieved steady state during 5 h milling process) was milled for 1-4 h. The results depicted that the milling time lower than 5 h, do not achieve to steady state conditions.

  15. Study of the ternary alloy systems Al-Ni-Fe and Al-Cu-Ru with special regard to quasicrystalline phases

    International Nuclear Information System (INIS)

    Lemmerz, U.

    1996-07-01

    Two ternary alloy-systems, the Al-Ni-Fe system and the Al-Cu-Ru system were studied with special regard to quasicrystalline phases. Isothermal sections were established in both systems in the stoichiometric area of the quasicrystalline phase. In the Al-Ni-Fe system a new stable decagonal phase was found. Its stoichiometric range is very small around Al 71.6 Ni 23.0 Fe 5.4 . The temperature range in which it is stable lies between 847 and 930 C. The decagonal phase undergoes a eutectoid reaction to the three crystalline phases Al 3 Ni 2 , Al 3 Ni and Al 13 Fe 4 at 847 C. It melts peritectically at 930 C forming Al 13 Fe 4 , Al 3 Ni 2 and a liquid. The investigations in the Al-Cu-Ru system concentrated on the phase equilibria between the icosahedral phase and its neighbouring phases in a temperature range between 600 and 1000 C. The icosahedral phase was observed in the whole temperature range. The investigated stoichiometric area extends down to Al contents of 45%, which allows the fields of existence to be determined for the ternary phases α-AlCuRu, the icosahedral phase and Al 7 Cu 2 Ru. Binary phases were determined down to the upper (high Al content) border of AlRu. No hitherto unknown phase was observed in the investigated area. Rietveld analyses were carried out on α-AlCuRu and Al 7 Cu 2 Ru showing some discrepancies from the α-AlMnSi structure taken as a base for α-AlCuRu and confirming the Al 7 Cu 2 Fe structure for Al 7 Cu 2 Ru. (orig.)

  16. Al-Cu-Li and Al-Mg-Li alloys: Phase composition, texture, and anisotropy of mechanical properties (Review)

    Science.gov (United States)

    Betsofen, S. Ya.; Antipov, V. V.; Knyazev, M. I.

    2016-04-01

    The results of studying the phase transformations, the texture formation, and the anisotropy of the mechanical properties in Al-Cu-Li and Al-Mg-Li alloys are generalized. A technique and equations are developed to calculate the amounts of the S1 (Al2MgLi), T1 (Al2CuLi), and δ' (Al3Li) phases. The fraction of the δ' phase in Al-Cu-Li alloys is shown to be significantly higher than in Al-Mg-Li alloys. Therefore, the role of the T1 phase in the hardening of Al-Cu-Li alloys is thought to be overestimated, especially in alloys with more than 1.5% Li. A new model is proposed to describe the hardening of Al-Cu-Li alloys upon aging, and the results obtained with this model agree well with the experimental data. A texture, which is analogous to that in aluminum alloys, is shown to form in sheets semiproducts made of Al-Cu-Li and Al-Mg-Li alloys. The more pronounced anisotropy of the properties of lithium-containing aluminum alloys is caused by a significant fraction of the ordered coherent δ' phase, the deformation mechanism in which differs radically from that in the solid solution.

  17. Pornographie als Metapher

    Directory of Open Access Journals (Sweden)

    Caroline Schubarth

    2010-03-01

    Full Text Available In diesem Artikel werden unterschiedliche metaphorische Verwendungen des Pornografiebegriffs und deren Implikationen untersucht. Während die Existenz von Pornografie der feministischen Anti-Porno-Bewegung als Erklärung für die anhaltende Diskriminierung von Frauen in westlichen Gesellschaften dient, nutzen rechtskonservative Kräfte den Pornografievorwurf als Rechtfertigung für die Zensur von als deviant empfundenen Identitäten und sexuellen Praktiken.This article examines different metaphorical uses of the term pornography and the resulting implications. While the existence of pornography for the feminist anti-porno movement serves as factor in the continuing discrimination of women in western societies, conservative powers on the right use the allegation of pornography as a justification for censorship of those identities and sexual practices deemed deviant.

  18. An optimal high thermal conductive graphite microchannel for electronic device cooling

    Directory of Open Access Journals (Sweden)

    Jorge Mario Cruz-Duarte

    2015-01-01

    Full Text Available Este artículo describe el diseño de un microcanal rectangular óptimo, construido con grafi to de alta conductividad térmica (HTCG. Para simular el disipador de microcanales propuesto se utilizó el modelo de resistencia térmica total y el criterio de minimización de la generación de entropía. Para solucionar el problema de optimización, se utilizó el algoritmo de enjambre de partículas unifi cado (UPSO. Los resultados mostraron un efecto marcado al utilizar este conductor térmico, en comparación con materiales tradicionales (tales como aluminio, y utilizando aire y amoniaco gaseoso como fl uidos de trabajo. También se reporta el efecto relativo de las resistencias térmicas de constricción, de convección y del fl uido, sobre la resistencia térmica equivalente total. Como un ejemplo demostrativo del efecto causado al cambiar la naturaleza del refrigerante, se seleccionó un nanofl uido de dióxido de titanio. Se encontró que el número de Nusselt es perceptiblemente menor, cuando se utiliza un nanofl uido como refrigerante y cuando el material con que está construido el microcanal es HTCG.

  19. Contribución a la modelación de la distribución fraccional magnética de la mena oxidada niquelífera de Cuba

    Directory of Open Access Journals (Sweden)

    George Agyei

    2011-12-01

    Full Text Available Con el propósito de ahondar en el conocimiento de las regularidades de distribución de la mena ferroniquelífera oxidada que se suministra al proceso Caron en Moa, Cuba, la mena se fraccionó en clases de tamaño según distintas intensidades de inducción magnética para determinar la distribución másica y del contenido. Se caracterizaron las propiedades físicas más contrastantes (tamaño de partículas y susceptibilidad magnética mediante métodos de distribución fraccional y técnicas de Fluorescencia de Rayos–X y Absorción Atómica. Como resultado se describen las regularidades de la distribución másica y del contenido de níquel, cobalto, hierro, aluminio y SiO2 por intervalos de tamaño de las partículas e intensidades de corriente. Además, se determinan las funciones de distribución másica del contenido y sus combinaciones bidimensionales, herramientas que aportan nuevos conocimientos sobre las potencialidades de preconcentración de los componentes, lo que contribuiría a regular la calidad de mena niquelífera suministrada al proceso extractivo Caron

  20. Strain Balanced AlGaN/GaN/AlGaN nanomembrane HEMTs.

    Science.gov (United States)

    Chang, Tzu-Hsuan; Xiong, Kanglin; Park, Sung Hyun; Yuan, Ge; Ma, Zhenqiang; Han, Jung

    2017-07-25

    Single crystal semiconductor nanomembranes (NM) are important in various applications such as heterogeneous integration and flexible devices. This paper reports the fabrication of AlGaN/GaN NMs and NM high electron mobility transistors (HEMT). Electrochemical etching is used to slice off single-crystalline AlGaN/GaN layers while preserving their microstructural quality. A double heterostructure design with a symmetric strain profile is employed to ensure minimal residual strain in freestanding NMs after release. The mobility of the two-dimensional electron gas (2DEG), formed by the AlGaN/GaN heterostructure, is noticeably superior to previously reported values of many other NMs. AlGaN/GaN nanomembrane HEMTs are fabricated on SiO 2 and flexible polymeric substrates. Excellent electrical characteristics, including a high ON/OFF ratio and transconductance, suggest that III-Nitrides nanomembranes are capable of supporting high performance applications.

  1. Validated thermodynamic prediction of AlP and eutectic (Si) solidification sequence in Al-Si cast alloys

    International Nuclear Information System (INIS)

    Liang, S M; Schmid-Fetzer, R

    2016-01-01

    The eutectic microstructure in hypoeutectic Al-Si cast alloys is strongly influenced by AlP particles which are potent nuclei for the eutectic (Si) phase. The solidification sequence of AlP and (Si) phases is, thus, crucial for the nucleation of eutectic silicon with marked impact on its morphology. This study presents this interdependence between Si- and P-compositions, relevant for Al-Si cast alloys, on the solidification sequence of AlP and (Si). These data are predicted from a series of thermodynamic calculations. The predictions are based on a self-consistent thermodynamic description of the Al-Si-P ternary alloy system developed recently. They are validated by independent experimental studies on microstructure and undercooling in hypoeutectic Al-Si alloys. A constrained Scheil solidification simulation technique is applied to predict the undercooling under clean heterogeneous nucleation conditions, validated by dedicated experimental observations on entrained droplets. These specific undercooling values may be very large and their quantitative dependence on Si and P content of the Al alloy is presented. (paper)

  2. Phase diagrams of aluminium alloys of Al-Cu-Mg, Al-Mg-Si-Cu, and Al-Mg-Li system

    International Nuclear Information System (INIS)

    Ber, L.B.; Kaputkin, E.Ya.

    2001-01-01

    Isothermal diagrams of phase transformations (DPT) and temperature-time charts (TTC) of variation of electric conductivity and of mechanical features at tension were plotted following thermal treatment according to the pattern of direct hardening and ageing and according to the pattern of normal aging for D16 commercial alloy, Al-Cu-Mg model alloy of the same system, AD37 commercial alloys of Al-Mg-Si-Cu and 1424 one of Al-Li-Mg system. Phase transformations were studied by means of fluorescence electron microscopy, micro-X-ray spectral analysis, X-ray phase analysis of single crystals and polycrystals and differential scanning calorimetry. For every alloy comparison of TTC and DPT enables to clarity the mechanism of phase composition effect on features and to optimize conditions of hardening cooling and ageing [ru

  3. Superhydrophobic ZnAl double hydroxide nanostructures and ZnO films on Al and glass substrates

    Energy Technology Data Exchange (ETDEWEB)

    De, Debasis, E-mail: debasis.de@bcrec.ac.in [Electronics and Instrumentation Engineering Department, Dr. B C Roy Engineering College, Durgapur, West Bengal 713206 (India); Sarkar, D.K. [Centre Universitaire de Recherche sur l' Aluminium (CURAL), L' Université du Québec à Chicoutimi, 555 Blvd. Université, Chicoutimi, Saguenay, Québec G7H 2B1 (Canada)

    2017-01-01

    Superhydrophobic nanostructured ZnAl: layered double hydroxides (LDHs) and ZnO films have been fabricated on Al and glass substrates, respectively, by a simple and cost effective chemical bath deposition technique. Randomly oriented hexagonal patterned of ZnAl: LDHs thin nanoplates are clearly observed on Al-substrate in the scanning electron microscopic images. The average size of these hexagonal plates is ∼4 μm side and ∼30 nm of thickness. While on the glass substrate, a oriented hexagonal patterned ZnO nanorods (height ∼5 μm and 1 μm diameter) are observed and each rod is further decorated throughout the top few nanometers with several nanosteps. At the top of the nanorod, a perfectly hexagonal patterned ZnO surface with ∼250 nm sides is observed. The tendency to form hexagonal morphological features is due to the hexagonal crystal structure of ZnO confirmed from X-ray diffraction patterns and transmission electron microscopy image. The ZnAl: LDHs and/or ZnO coated substrates have been passivated by using stearic acid (SA) molecules. Infrared spectra of passivated ZnAl: LDHs coated substrates confirm the presence of SA. X-ray diffraction pattern also corroborates the results of infrared spectrum. The contact angle of the as prepared samples is zero. The superhydrophobicity is achieved by observing contact angle of ∼161° with a hysteresis of ∼4° for Al-substrate. On the glass substrate, a higher contact angle of ∼168° with a lower hysteresis of ∼3° is observed. A lower surface roughness of ∼4.93 μm is measured on ZnAl: LDHs surface layer on the Al substrate as compare to a higher surface roughness of 6.87 μm measured on ZnO layer on glass substrate. The superhydrophobicity of passivated nanostructured films on two different substrates is observed due to high surface roughness and low surface energy. - Highlights: • ZnAl: layered double hydroxides (LDHs) nanoplates are fabricated on Al substrate. • ZnO nanorods are fabricated on

  4. Formation of Nb3Al in powder processed Nb-Al superconductors

    International Nuclear Information System (INIS)

    Johnson, P.E.

    1987-05-01

    In high magnetic fields, the critical current density is strongly dependent on the upper critical field, which is determined primarily by the stoichiometry of the Nb 3 Al. The critical temperature (T/sub c/), like the upper critical field, is considered to be a measure of the ''intrinsic'' quality of the superconductor, indicating the stoichiometry, order, and strain. If the A15 phase is stoichiometric and well ordered, a high T/sub c/ (and high H/sub C 2 /) is expected, regardless of the volume fraction of superconductor. On the other hand, if sigma phase is present with the A15, the resultant composition gradient across the sigma-A15 interface(s) requires that some of the A15 be off-stoichiometric, and therefore that the T/sub c/ (and H/sub C 2 /) be low. Thus the extent of the A15 (Nb 3 Al) reaction and the quality of the A15 formed are interdependent. This work focuses on the factors that control the extent of Nb 3 Al formation in Nb/Al powder wires. The morphology and content of the reacted and unreacted wires are studied in optical, SEM, and TEM micrographs. Critical current density data and its dependence on processing are explained in terms of the unreacted microstructure and its effect on the extent of Nb 3 Al formation. As a method of improving the critical current density, a new variation of the conventional powder process for wire manufacturing is developed and tested

  5. Al-Si/B{sub 4}C composite coatings on Al-Si substrate by plasma spray technique

    Energy Technology Data Exchange (ETDEWEB)

    Sarikaya, Ozkan [Sakarya University, Faculty of Engineering, Department of Mechanical Engineering, Esentepe Campus, Sakarya 54187 (Turkey); Anik, Selahaddin [Sakarya University, Faculty of Engineering, Department of Mechanical Engineering, Esentepe Campus, Sakarya 54187 (Turkey); Aslanlar, Salim [Sakarya University, Faculty of Technical Education, Department of Mechanical Engineering, Esentepe Campus, Sakarya 54187 (Turkey); Cem Okumus, S. [Sakarya University, Faculty of Engineering, Department of Metallurgical and Materials Engineering, Esentepe Campus, Sakarya 54187 (Turkey); Celik, Erdal [Dokuz Eylul University, Engineering Faculty, Department of Metallurgical and Materials Engineering, Buca, Izmir 35160 (Turkey)]. E-mail: erdal.celik@deu.edu.tr

    2007-07-01

    Plasma-sprayed coatings of Al-Si/B{sub 4}C have been prepared on Al-Si piston alloys for diesel engine motors. The Al-Si/B{sub 4}C composite powders including 5-25 wt% B{sub 4}C were prepared by mixing and ball-milling processes. These powders were deposited on Al-Si substrate using an atmospheric plasma spray technique. The coatings have been characterised with respect to phase composition, microstructure, microhardness, bond strength and thermal expansion. It was found that Al, Si, B{sub 4}C and Al{sub 2}O{sub 3} phases were determined in the coatings with approximately 600 {mu}m thick by using X-ray diffraction analysis. Scanning electron microscope observation revealed that boron carbide particles were uniformly distributed in composite coatings and B{sub 4}C particles were fully wetted by Al-Si alloy. Also, no reaction products were observed in Al-Si/B{sub 4}C composite coatings. It was found that surface roughness, porosity, bond strength and thermal expansion coefficient of composite coatings decreased with increasing fraction of the boron carbide particle. It was demonstrated that the higher the B{sub 4}C content, the higher the hardness of coatings because the hardness of B{sub 4}C is higher than that of Al-Si.

  6. Fluctuations of charge variance and interaction time for dissipative processes in 27 Al + 27 Al collision

    International Nuclear Information System (INIS)

    Berceanu, I.; Andronic, A.; Duma, M.

    1999-01-01

    The systematic studies of dissipative processes in light systems were completed with experiments dedicated to the measurement of the excitation functions in 19 F + 27 Al and 27 Al + 27 Al systems in order to obtain deeper insight on DNS configuration and its time evolution. The excitation function for 19 F + 27 Al system evidenced fluctuations larger than the statistical errors. Large Z and angular cross correlation coefficients supported their non-statistical nature. The energy dependence of second order observables, namely the second moment of the charge distribution and the product ω·τ (ω - the angular velocity of the DNS and τ its mean lifetime) extracted from the angular distributions were studied for 19 F + 27 Al case. In this contribution we are reporting the preliminary results of similar studies performed for 27 Al + 27 Al case. The variance of the charge distribution were obtained fitting the experimental charge distribution with a Gaussian centered on Z = 13 and the product ω·τ was extracted from the angular distributions. The results for 19 F + 27 Al case are confirmed by a preliminary analysis of the data for 27 Al + 27 Al system. The charge variance and ω·τ excitation functions for Z = 11 fragment are represented together with the excitation function of the cross section. One has to mention that the data for 27 Al + 27 Al system were not corrected for particle evaporation processes. The effect of the evaporation corrections on the excitation function was studied using a Monte Carlo simulation. The α particle evaporation was also included and the evaluation of the particle separation energies was made using experimental masses of the fragments. The excitation functions for 27 Al + 27 Al system for primary and secondary fragments were simulated. No structure due to particle evaporation was observed. The correlated fluctuations in σ Z and ω·τ excitation functions support a stochastic exchange of nucleons as the main mechanism for

  7. Unprecedented Al supersaturation in single-phase rock salt structure VAlN films by Al+ subplantation

    Science.gov (United States)

    Greczynski, G.; Mráz, S.; Hans, M.; Primetzhofer, D.; Lu, J.; Hultman, L.; Schneider, J. M.

    2017-05-01

    Modern applications of refractory ceramic thin films, predominantly as wear-protective coatings on cutting tools and on components utilized in automotive engines, require a combination of excellent mechanical properties, thermal stability, and oxidation resistance. Conventional design approaches for transition metal nitride coatings with improved thermal and chemical stability are based on alloying with Al. It is well known that the solubility of Al in NaCl-structure transition metal nitrides is limited. Hence, the great challenge is to increase the Al concentration substantially while avoiding precipitation of the thermodynamically favored wurtzite-AlN phase, which is detrimental to mechanical properties. Here, we use VAlN as a model system to illustrate a new concept for the synthesis of metastable single-phase NaCl-structure thin films with the Al content far beyond solubility limits obtained with conventional plasma processes. This supersaturation is achieved by separating the film-forming species in time and energy domains through synchronization of the 70-μs-long pulsed substrate bias with intense periodic fluxes of energetic Al+ metal ions during reactive hybrid high power impulse magnetron sputtering of the Al target and direct current magnetron sputtering of the V target in the Ar/N2 gas mixture. Hereby, Al is subplanted into the cubic VN grains formed by the continuous flux of low-energy V neutrals. We show that Al subplantation enables an unprecedented 42% increase in metastable Al solubility limit in V1-xAlxN, from x = 0.52 obtained with the conventional method to 0.75. The elastic modulus is 325 ± 5 GPa, in excellent agreement with density functional theory calculations, and approximately 50% higher than for corresponding films grown by dc magnetron sputtering. The extension of the presented strategy to other Al-ion-assisted vapor deposition methods or materials systems is straightforward, which opens up the way for producing supersaturated single

  8. Erudición y nostalgia. Al-Hanīn ilà l-awtān en el editor de al-Faraŷ ba,d al-šidda de al-Tanūjī

    Directory of Open Access Journals (Sweden)

    Garulo, Teresa

    2012-06-01

    Full Text Available If you want to read a book, a medieval Arabic book, that talks to you about man and his relation with power (God’s power or any kind of worldly power, or about daily life in 10th century Basra or Baghdad, you will probably choose al-Tanūkhī’s works. His Nishwār al-muhādara wa-l-mudhākara or al-Faraj ba,d al-shidda are so widely and so well provided with stories, anecdotes, historical narratives, etc., that you won’t be able to drop it and probably will forget to read the many comments and marginal notes by, Abbūd al-Shāljī, its editor. But if you are wise enough, you will read everything he writes, because you will find in his remarks not only a sustained scholarliness but a fascinating evocation of his life in Irak, mostly in the thirties, with its cooking, manners and customs, and a pang of nostalgia that deserves, I think, at least a note or a friendly comment. In this paper I try to analyse some of his nostalgic memories of Baghdad and its people and places.Uno de los temas clásicos de la literatura árabe, casi desde sus comienzos, es la nostalgia de la tierra natal (al-hanīn ilà l-awtān. Experiencia dolorosa de extrañamiento, que se nutre de las crisis políticas, la nostalgia ha dado lugar a obras que buscan recrear un pasado o unos lugares amados, que sólo la memoria es capaz de recuperar. En este artículo trato de mostrar cómo se articula la nostalgia de Iraq, y, más concretamente, de Bagdad, dentro del aparato crítico de al-Faraŷ ba,da l-šidda de al-Tanūjī (329-384/941-994 (con el apoyo de Nišwār al-muhādara, también de dicho autor en la edición de, Abbūd al-Šālŷī, publicada en los años setenta. La representación que hace al-Tanūjī de la vida cotidiana de la capital abbasí, expresada a través de un lenguaje claro y natural, en el que tienen cabida expresiones populares, suscita en al-Šālŷī toda una serie de remembranzas, sobre todo de sus años juveniles, que se desbordan en sus notas, e

  9. Lou Gehrig's Disease (ALS)

    Science.gov (United States)

    ... disease. Who Gets ALS? Although this disease can strike anyone, ALS is extremely rare in kids. According ... home to provide care that the family cannot handle alone. Living With Lou Gehrig's Disease Living with ...

  10. Difficulties on study of ISM 26Al and a possible new way to nucleosynthesize 26Al-SNIa

    International Nuclear Information System (INIS)

    Peng Qiuhe

    1995-01-01

    Some observational results of the 1.809 MeV gamma-ray emitted by decay of the interstellar medium (ISM) 26 Al, which are obtained by spacecraft during (1979-1992) are firstly introduced. Secondly, both Mg-Al chain and Ne-Na cycle of nuclear reactions are discussed. Thirdly, some new experiments of nuclear physics, which are related with the question of the ISM 26 Al(e.g. measurements of the cross section of the nuclear reactions in the MgAl chain and in the NeNa cycle) are introduced. Then, comparing some experiments of nuclear physics, some difficulties confronted on various models responsible for the ISM 26 Al are discussed. The conclusions are: 1) all of hydrostatic H-burning models and all current nova models are hard to provide enough ISM 26 Al to be detected; 2) SN II + SN I b models are promising on responsibility for the half of ISM 26 Al, although current SN II + SN I b models should be improved, besides. Proposal of a new way to nucleosynthesizse 26 Al, 14 N + 16 O→ 26 Al + α, is suggested. SNI a as a possible source of the ISM 26 Al is discussed (63 refs.)

  11. Effect of the interface in laminated composites of Al-1100 and Al-2024

    International Nuclear Information System (INIS)

    Godefroid, L.B.

    1983-01-01

    Laminated composites consisting of alternating layers of Al-1100 and Al-2024 were produced by hot rolling, with 45% Al-2024 volume fraction. These composites were subjected to cyclic thermal treatment (various numbers of cycles) and to isothermal treatment (various numbers of cycles) and to isothermal treatment (at peak temperature and for times equivalent to those of the thermal cycles. Microhardness, tensile and fatigue crack arrester modes) were studied in the initial state and after treatments. (E.G.) [pt

  12. AlGaN-Based Deep-Ultraviolet Light Emitting Diodes Fabricated on AlN/sapphire Template

    International Nuclear Information System (INIS)

    Li-Wen, Sang; Zhi-Xin, Qin; Hao, Fang; Yan-Zhao, Zhang; Tao, Li; Zheng-Yu, Xu; Zhi-Jian, Yang; Bo, Shen; Guo-Yi, Zhang; Shu-Ping, Li; Wei-Huang, Yang; Hang-Yang, Chen; Da-Yi, Liu; Jun-Yong, Kang

    2009-01-01

    We report on the growth and fabrication of deep ultraviolet (DUV) light emitting diodes (LEDs) on an AlN template which was grown on a pulsed atomic-layer epitaxial buffer layer. Threading dislocation densities in the AlN layer are greatly decreased with the introduction of this buffer layer. The crystalline quality of the AlGaN epilayer is further improved by using a low-temperature GaN interlayer between AlGaN and AlN. Electroluminescences of different DUV-LED devices at a wavelength of between 262 and 317 nm are demonstrated. To improve the hole concentration of p-type AlGaN, Mg-doping with trimethylindium assistance approach is performed. It is found that the serial resistance of DUV-LED decreases and the performance of DUV-LED such as EL properties is improved. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  13. Surface study and thickness control of thin Al2O3 film on Cu-9%Al(111) single crystal

    International Nuclear Information System (INIS)

    Yamauchi, Yasuhiro; Yoshitake, Michiko; Song Weijie

    2004-01-01

    We were successful in growing a uniform flat Al 2 O 3 film on the Cu-9%Al(111) surface using the improved cleaning process, low ion energy and short time sputtering. The growth of ultra-thin film of Al 2 O 3 on Cu-9%Al was investigated using Auger electron spectroscopy (AES) and a scanning electron microscope (SEM). The Al 2 O 3 film whose maximum thickness was about 4.0 nm grew uniformly on the Cu-9%Al surface. The Al and O KLL Auger peaks of Al 2 O 3 film shifted toward low kinetic energy, and the shifts were related to Schottky barrier formation and band bending at the Al 2 O 3 /Cu-9%Al interface. The thickness of Al 2 O 3 film on the Cu-9%Al surface was controlled by the oxygen exposure

  14. Dissolution of aluminium; Disolucion de aluminio

    Energy Technology Data Exchange (ETDEWEB)

    Uriarte Hueda, A; Berberana Eizmendi, M; Pereira Sanchez, G

    1968-07-01

    The dissolution of aluminum with acid solutions ( nitric acid-mercuric nitrate) and alkaline solutions (sodium hydroxide-sodium nitrate) has been studied. The instantaneous dissolution rate (IDR) has been studied in function of the concentration of the used reagents and the dissolution temperature. The complete dissolution has been included in the second part of this report, to know the total dissolution time, the consume of reagents and the stability of the resultant solutions. (Author)

  15. Microstructural and mechanical properties of Al-Mg/Al{sub 2}O{sub 3} nanocomposite prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Safari, J., E-mail: safari.jam@gmail.com [Department of Material Science and Engineering, Shahid Bahonar University of Kerman, P.O. Box No. 76135-133, Kerman (Iran, Islamic Republic of); Akbari, G.H. [Department of Material Science and Engineeri