Browsing by Author "Guridi, J. R."
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Item L'Al-TiB 2, un matériau pour les applications du secteur des transports nécessitant résistances aux températures élevées et à l'usure(2002-12) Goñi, J.; Egizabal, P.; Coleto, J.; Poutier, M. A.; Guridi, J. R.; Centros PRE-FUSION TECNALIA - (FORMER); Tecnalia Research & Innovation; MercadoThe transport industry is continuously seeking new light materials to comply with the low fuel consumption policies and enhanced technical requirements. The use of Metal Matrix Composites (MMCs) is seen as a feasible alternative to substitute several grey cast iron steel and non reinforced aluminium alloys components as they present outstanding specific properties, high wear resistance as well as low Coefficient of Thermal Expansion (CTE). The results obtained during a research project that studied the actual possibilities, processing optimisation and mechanical properties of an aluminium matrix composite reinforced with in-situ produced TiB 2 ceramic particles are presented. Railway and automotive components were produced by Gravity Casting, High Pressure Die Casting (HPDC) and a variant of the Sand Casting process called "Multipouring" and the melt behaviour and obtained mechanical properties were analysed and evaluated. The material presented a remarkable improvement of properties when compared with the corresponding non-reinforced alloys. Furthermore, the presence of the TiB 2 particles conferred a thixotropic nature to the melt whose positive effects during the filling step could also be noticed during the production of prototypes.Item Al-TiB2: Un materiau alternatif pour des applications resistant a l'usure et aux hautes temperatures dans l'industrie du transfert(2002-08) Goni, J.; Egizabal, P.; Coleto, J.; Poutier, M. A.; Guridi, J. R.; Centros PRE-FUSION TECNALIA - (FORMER); Tecnalia Research & Innovation; MercadoResults obtained in a study of real-life possibilities, process optimization and mechanical properties of aluminum metal matrix composites reinforced by particles of ceramic TiB2 are presented and discussed. Vehicle and train components have been made of those materials by gravity molding, high-pressure casting and the so-called Pultipouring process. The results have been analyzed and evaluated from the standpoint of casting and mechanical properties. Reinforcement resulted in a significant improvement and the presence of TiB2 made the alloy thixotropic, which had a positive effect on the process.Item Development of automotive components locally reinforced with metal matrix composite inserts(2000-09) Goñi, J.; Fernández, R.; Mitxelena, I.; Coleto, J.; Guridi, J. R.; Centros PRE-FUSION TECNALIA - (FORMER); Biomateriales; Tecnalia Research & Innovation; MercadoMetal Matrix Composites (MMC) based on aluminum alloys are currently one of the most interesting alternatives, due to their high performance level, for different commercial applications. The main objective of this work is the development of locally reinforced automotive components where the MMC insert is located in the areas where the level of performance needed is higher than that offered by conventional materials. In this way, the production of competitive products with a high performance level will be possible in which only concrete areas, mainly those in need of a high wear resistance, of the part are reinforced. Two conventional foundry technologies have been previously selected (High Pressure Die Casting and Low Pressure Casting), that are known to be largely competitive. Likewise, two different kinds of MMC inserts have been initially considered, inserts made of AllSiCp commercial MMCs and inserts mode of porous preforms, for the fabrication of two different automotive components: a clutch disc and a ventilated brake disc.Item High performance automotive and railway components made from novel competitive aluminium composites(2003-07-01) Goñi, J.; Egizabal, P.; Coleto, J.; Mitxelena, I.; Leunda, I.; Guridi, J. R.; Centros PRE-FUSION TECNALIA - (FORMER); Tecnalia Research & Innovation; MercadoThe traditional materials encounter difficulties to comply with all the properties required by new components under service conditions. The automotive and the railway industries require low cost solutions to improve the final performance of components made from steel, cast iron, or even conventional aluminium alloys (e.g. clutch discs, brake discs, or pistons). Weight reduction, improvement in wear behaviour, high thermal conductivity, low coefficient of thermal expansion, and easy recycling are sought, among other characteristics, in order to obtain more efficient products leading to a reduction of pollutant emissions. The range of materials that can meet these requirements is presently very narrow and their final price is more expensive (e.g. aluminium matrix composites) than currently used materials. In this paper a new low cost metal matrix composite that has been used to produce pistons, clutch discs, and train brake discs is presented.Item High pressure die casting (HPDC) of advanced reinforced aluminium alloys(2004-06) Goñi, J.; Eguizabal, P.; Coleto, J.; Guridi, J. R.; Garitagoitia, I.; Garitagoitia, E.; Barbarias, E.; Centros PRE-FUSION TECNALIA - (FORMER); Tecnalia Research & Innovation; MercadoAn advanced material based on a AlSi8Cu3Fe alloy reinforced with 6%wt. of Titanium Diboride (TiB2) particles was employed to produce demonstrator clutch discs and to compare the obtained properties with those of the corresponding non reinforced alloy. The new material was produced through an in-situ reaction in which two salts were incorporated into the aluminium alloy melt to produce the reinforcing particles through an exothermal chemical reaction. The material so formed was first used to obtain samples through the direct Squeeze Casting technology at lab scale. Afterwards, it was also employed to produce some demonstrator prototypes with a conventional industrial High Pressure Die Casting (HPDC) equipment. Results obtained with the reinforced material with the Squeeze Casting and HPDC technologies are presented and compared to those obtained with the corresponding non reinforced equivalent. The effect of the TiB2 particles was analysed in terms of enhancement of mechanical properties at high temperatures, thermal properties, processing, etc. Minor changes had to be implemented in the moulds and equipments used to produce the final samples and components. The melt was stirred in order to avoid the settling phenomenon that might have taken place due to the difference of the density of the particles and the alloy. The processing parameters had to be fixed in order to take into account the different viscosity, castability and solidification pattern of the new material. Information on the optimization of the casting processes and properties of the Squeeze Casting and HPDC samples obtained are shown.