DSpace Collection:

Friction coefficients and wear rates of different orthodontic archwires in artificial saliva

Thu, 09 May 2013 14:46:28 GMT

Title: Friction coefficients and wear rates of different orthodontic archwires in artificial saliva Authors: Alfonso, M.V.; Espinar, Eduardo; Llamas, José María; Rupérez de Gracia, Elisa; Manero Planella, José María; Barrera, J.M; Solano, E.; Gil Mur, Francisco Javier Abstract: The aim of this paper is to analyze the influence of the nature of the orthodontic archwires on the friction coefficient and wear rate against materials used commonly as brackets (Ti–6Al–4V and 316L Stainless Steel). The mate- rials selected as orthodontic archwires were ASI304 stainless steel, NiTi, Ti, TiMo and NiTiCu. The array archwire’s materials selected presented very similar roughness but different hardness. Materials were chosen from lower and higher hardness degrees than that of the brackets. Wear tests were carried out at in artificial saliva at 37 C. Results show a linear relationship between the hardness of the materials and the friction coefficients. The material that showed lower wear rate was the ASI304 stainless steel. To prevent wear, the wire and the brackets have high hardness values and in the same order of magnitude.

Aplicación de tratamientos térmicos T5 y T6 a la aleación L2630 conformada por SSR

Mon, 11 Feb 2013 12:26:21 GMT

Title: Aplicación de tratamientos térmicos T5 y T6 a la aleación L2630 conformada por SSR Authors: Campillo Betbese, Manel; Baile Puig, Maria Teresa; Martín Fuentes, Enrique; Forn Alonso, Antonio Abstract: En este trabajo se muestran los resultados obtenidos al aplicar tratamientos térmicos T5 y T6, a componentes de aluminio L-2630, conformados por Semi-Solid Rheocasting (SSR). El estudio de los efectos de la temperatura y el tiempo de puesta en solución, y de las condiciones de temple y envejecimiento artificial, ha permitido optimizar las propiedades mecánicas del componente. La experimentación se ha realizado mediante ensayos de dureza Brinell, ensayos de tracción y microscopía óptica y electrónica. Las propiedades mecánicas de los componentes producidos por SRR alcanzan valores análogos a los obtenidos por colada en coquilla y sometidos a los mismos tratamientos térmicos.

Teaching engineering with autonomous learning tools: good practices in GRAPAU-RIMA

Fri, 04 Jan 2013 11:39:40 GMT

Title: Teaching engineering with autonomous learning tools: good practices in GRAPAU-RIMA Authors: Marcé Nogué, Jordi; Salán Ballesteros, Maria Núria; Aragoneses Aguado, Andrés; Bernat Masó, Ernest; Escrig Pérez, Christian; Otero Calviño, Beatriz; Rupérez de Gracia, Elisa; Illescas Fernandez, Silvia

A low elastic modulus Ti-Nb-Hf alloy bioactivated with an elastin-like

Thu, 13 Dec 2012 10:32:19 GMT

Title: A low elastic modulus Ti-Nb-Hf alloy bioactivated with an elastin-like Authors: González, Marta; Salvagni, Emiliano; Rodríguez Cabello, J.C.; Rupérez de Gracia, Elisa; Gil Mur, Francisco Javier; Manero Planella, José María; Peña, Javier Abstract: b-type titanium alloys with low Young’s modulus are desirable to reduce stress shielding effect and enhance bone remodeling for implants used to substitute failed hard tissue. For biomaterials application, the surface bioactivity is necessary to achieve optimal osseointegration. In the previous work, the low elastic modulus (43 GPa) Ti-25Nb-16Hf (wt %) alloy was mechanically and microstructurally characterized. In the present work, the biological behavior of Ti-25Nb- 16Hf was studied. The biological response was improved by surface modification. The metal surface was modified by oxygen plasma and subsequently silanized with 3-chloropropyl (triethoxy)silane for covalent immobilization of the elastin-like polymer. The elastin-like polymer employed exhibits RGD bioactive motives inspired to the extracellular matrix in order to improve cell adhesion and spreading. Upon modification, the achieved surface presented different physical and chemical properties, such as surface energy and chemical composition. Subsequently, osteoblast adhesion, cell numbers, and differentiation studies were performed to correlate surface properties and cell response. The general tendency was that the higher surface energy the higher cell adhesion. Furthermore, cell culture and immunofluorescence microscopy images demonstrated that RGD-modified surfaces improved adhesion and spreading of the osteoblast cell type.

Simulación del Proceso de Semisólidos Rheocasting (SSR®) en un componente de automoción con PROCAST

Thu, 07 Jun 2012 09:45:38 GMT

Title: Simulación del Proceso de Semisólidos Rheocasting (SSR®) en un componente de automoción con PROCAST Authors: Menargues Muñoz, Sergi; Baile Puig, Maria Teresa; Campillo Betbese, Manel; Picas Barrachina, Josep Anton; Forn Alonso, Antonio Abstract: La técnica Semi-Solid Rheocasting es una alternativa a los procesos de fundición tradicionales. La simulación numérica de estos métodos resulta muy útil para definir el proceso real. Se presenta un nuevo ensayo de campo para determinar parámetros tales como la temperatura, la velocidad, el llenado del molde y la solidificación. Las herramientas de simulación permiten comprender mejor los procesos, y de ese modo es posible predecir y eliminar los defectos potenciales antes de que ocurran. El componente objeto de este estudio es una cubierta de una pieza de automóvil elaborada con una aleación de aluminio de segunda fusión A380. El software utilizado para simular el proceso ha sido ProCAST de ESI Group. Las características de la microestructura se han analizado mediante microscopia óptica y electrónica. Todo ello ha procedido al desarrollo de un modelo basado en datos experimentales. Para el modelizado el estado semisólido se considera homogéneo, con propiedades thixotrópicas y su microestructura se define como un parámetro estructural. Se han comparado los resultados obtenidos con las pruebas reales.

Aplicación de tratamientos T5 y T6 a la aleación de aluminio L-2630 conformada por SSR.

Wed, 05 Oct 2011 14:24:41 GMT

Title: Aplicación de tratamientos T5 y T6 a la aleación de aluminio L-2630 conformada por SSR. Authors: Campillo Betbese, Manel; Baile Puig, Maria Teresa; Martín Fuentes, Enrique; Forn Alonso, Antonio Abstract: En este trabajo se muestran los resultados obtenidos al aplicar tratamientos térmicos T5 y T6, a componentes de aluminio L-2630, conformados por Semi-Solid Rheocasting (SSR). El estudio de los efectos de la temperatura y el tiempo de puesta en solución, y de las condiciones de temple y envejecimiento artificial, ha permitido optimizar las propiedades mecánicas del componente. La experimentación se ha realizado mediante ensayos de dureza Brinell, ensayos de tracción y microscopía óptica y electrónica. Las propiedades mecánicas de los componentes producidos por SRR alcanzan valores análogos a los obtenidos por colada en coquilla y sometidos a los mismos tratamientos térmicos.Ponencia presentada en el XI Congreso Tratermat (Marzo 2008). [Ponencia presentada en el XI Congreso Tratermat.]

Thixoextrusion of A357 aluminium alloy

Fri, 26 Nov 2010 14:55:55 GMT

Title: Thixoextrusion of A357 aluminium alloy Authors: Forn Alonso, Antonio; Vaneetveld, Gregory; Pierret, Jean-Christophe; Menargues Muñoz, Sergi; Baile Puig, Maria Teresa; Campillo Betbese, Manel; Rassili, Ahmed Abstract: The aim of this work is to attempt the application of A357 Al-Si-Mg cast alloy in the thixoextrusion process, evaluating the different forming parameters effect. Thixoextrusion offers several advantages compared with traditional hot-extrusion such as lower pressure, minor friction forces, higher material fluidity and longer tool life. This type of semi-solid process requires high solid fraction (0.70.85) is less sensitive to temperature drops and allows more stable material flow at higher speeds. To know the forming parameters that improve the mechanical properties of thixoextruded parts, some extrusion tests were carried out. The results were used as the main criteria for assessing the thixoforming viability of the A357 alloy.

The effect of injection conditions on the structural integrity of the components produced by semi-solid Rheocasting.

Mon, 21 Jun 2010 09:23:47 GMT

Title: The effect of injection conditions on the structural integrity of the components produced by semi-solid Rheocasting. Authors: Campillo Betbese, Manel; Baile Puig, Maria Teresa; Menargues Muñoz, Sergi; Forn Alonso, Antonio Abstract: This work is a contribution to improve understanding about the behaviour of components produced by semi-solid processes. The present study shows the effect of different conformation parameters on automotive cranking cover production obtained by Semi-Solid Rheocasting Process (SSR®). The components were produced using EN AC-46500 alloy, by an industrial plant with a 700 Ton HPDC machine and an IDRA SSR Station. The process parameters studied were slurry temperature, agitation time, speed injection and lubrication system. The characterization was carried out by microstructural analysis, X-rays and mechanical tests. The components show good mechanical properties, similar to those obtained by die cast. The process was simulated using the PROCAST program.

Surface finish effect on the anodizing behaviour of Al-Si components obtained by sub-liquidus casting process.

Mon, 21 Jun 2010 09:12:19 GMT

Title: Surface finish effect on the anodizing behaviour of Al-Si components obtained by sub-liquidus casting process. Authors: Menargues Muñoz, Sergi; Picas Barrachina, Josep Anton; Martín Fuentes, Enrique; Baile Puig, Maria Teresa; Campillo Betbese, Manel; Forn Alonso, Antonio Abstract: The aim of this study was to investigate the hard decorative anodizing components of A357 aluminium alloy, obtained in semisolid state by Sub Liquidus Casting® process, to improve its tribological properties and corrosion resistance. Components were heat treated in order to modify the shape and distribution of the eutectic silicon phase. The influence of shot peening pre-treatment on anodizing process was evaluated. Surface modifications were investigated as they might have beneficial effects on the wear and corrosion behaviour. Furthermore, the influence of surface condition on the anodization colouring behaviour of aluminium was studied. The microstructure and the surface finish influence on the anodic oxide film growth were studied by optical and scanning electron microscopy. Experiments using a tribometer (ball on disc configuration) were performed in order to evaluate the tribological properties of the material. Salt spray corrosion tests were used to study the corrosion properties before and after the anodizing process.

Heat treatments effect on the EN AC-46500 alloy produced by SSR

Tue, 02 Mar 2010 10:16:35 GMT

Title: Heat treatments effect on the EN AC-46500 alloy produced by SSR Authors: Campillo Betbese, Manel; Baile Puig, Maria Teresa; Martín Fuentes, Enrique; Forn Alonso, Antonio Abstract: This work demonstrates the possibility to apply T5 and T6 heat treatments to EN AC-46500 aluminium components conformed by Semi-Solid Rheocasting (SSR). The study of temperature and time effect in annealing, tempering and artificial aging conditions has permitted to optimize the component mechanical properties. The experimentation has been accomplished by means of hardness Brinell tests, tensile tests, optic and electronic microscopy. The mechanical properties obtained in SSR components, reach analogous values to the ones obtained by die cast components and submitted to the same heat treatments.

Decorartive PVD coatings as an environmentally clean alternative to chrome plating

Wed, 30 Dec 2009 16:24:03 GMT

Title: Decorartive PVD coatings as an environmentally clean alternative to chrome plating Authors: Picas Barrachina, Josep Anton; Baile Puig, Maria Teresa; Menargues Muñoz, Sergi; Martín Fuentes, Enrique; Forn Alonso, Antonio