Browsing by Author "Goni, J."
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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 Fabrication and characterisation of graphite/alumina reinforced copper composites(2000-12) Coupard, D.; Goni, J.; Silvain, J. F.; Centros PRE-FUSION TECNALIA - (FORMER)The infiltration of graphite/alumina preforms with a bronze alloy has been investigated taking into account the influence of the binder type, the graphite/alumina content in the preform and the percentage of binder in water. The preforms showing an acceptable rigidity have been infiltrated with a CuSn12 bronze alloy by squeeze casting considering two different pouring temperatures. The composite produced has been characterised in terms of density, Brinell hardness, coefficient of thermal expansion, as well as friction and wear behaviour. The coefficient of friction for the bronze matrix composite is around 0.17, being three times lower than that shown by the unreinforced copper alloy. Given the contact geometry (ball of steel against a planar sample) and testing conditions (20°C, dry sliding, 40% humidity), the composite wear rate is around twenty times lower that of the bronze, being 10-6mm2/kg for the composite and 2 × 10-5 mm22/kg for the bronze.Item Fabrication and squeeze casting infiltration of graphite/alumina preforms(1999-11-01) Coupard, D.; Goni, J.; Sylvain, J. F.; Centros PRE-FUSION TECNALIA - (FORMER)The manufacturing of a suitable rigid porous graphite/alumina preform has been investigated taking into account the influence of the binder type, the graphite/alumina content in the preform and the percentage of binder in water. The preforms showing an acceptable rigidity have been infiltrated with a CuSn12 bronze alloy by squeeze casting considering two different pouring temperatures. The composite quality is strongly influenced by both the graphite/alumina volume fractions and the binder type. The optimal quality has been obtained by infiltrating a Carsil 2000 binded preform containing 30 vol% graphite flakes and 70 vol% alumina fibres.Item Magnetic molding foundry process of non ferrous and ferrous alloys(2005) Geffroy, P. M.; Goni, J.; Lakehal, M.; Beaugnon, E.; Silvain, J. F.; Centros PRE-FUSION TECNALIA - (FORMER)Magnetic molding technology, is a good alternative process in order to improve the metallurgical quality and dimensional tolerances of the final components that are presently produced through Lost Foam process. The first development of the magnetic molding process was performed at the same time of the lost foam process more than thirty years ago but it has never reached the same industrial development. The purpose of this study is to introduce the magnetic molding process, and to define the advantages and the characteristics of this process. Particular attention is given to the comparative results obtained with the lost foam and the magnetic molding processes with aluminum and grey cast iron. Eventually, the main factors involved in the magnetic molding process are discussed.Item Study of the thermal treatment of an alumina short fibre reinforced aluminium composite(1997) Garcia-Romero, A.; Goni, J.; Coleto, J.; Castro, M. C.; Coupard, D.; Palacios, J. K.; Centros PRE-FUSION TECNALIA - (FORMER); MercadoThe present paper deals with the problems found in the determination of peak hardness ageing conditions by means of Vickers microhardness measurement, in a Squeeze Cast Al-12Si-1Cu-1Mg-1Ni alloy partially reinforced with 15% δ-Alumina short fibre. Vickers measurement demonstrated to be not representative from the ageing process due to the large percentage of hard intermetallic phases plus fibres, which made not possible to perform reliable and reproducible measurements. The alternative method selected for the determination of peak hardness due to the ageing treatment is the measurements of the Brinnell macrohardness. This method, however, has poor sensitivity, and the final determination of the optimum ageing conditions should be performed by tensile testing.Item Wear behaviour of copper matrix composites(1997) Coupard, D.; Castro, M. C.; Coleto, J.; Garcia, A.; Goni, J.; Palacios, J. K.; Mercado; Centros PRE-FUSION TECNALIA - (FORMER)Wear and friction behavior of CuSnl2 bronze and CuSnl2 bronze/graphite-alumina composites have been investigated. The CuSnl2 composite shows excellent wear resistance and a lower coefficient of friction with respect to its matrix alloy. The tribological properties of the composite are mainly attributed to the thin layer of graphite at the surface of the wear track impeding the metal-to-metal contact. Thus, the coefficient of friction of the CuSnl2 composite is three times lower than that of the CuSnl2 bronze and the composite wear loss could not be detected after a 30 minutes wear test under a load and velocity of respectively 30 Kgs and 166 mm/s.