Browsing by Author "Castro, M. C."
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Item Microstructure-properties relationship of AS9U3/SiCp composites formed by sand and permanent mold casting(1997) Goñi, J.; Coleto, J.; García, A.; Palacios, J. K.; Castro, M. C.; Coupard, D.; Arriaran, J.; Centros PRE-FUSION TECNALIA - (FORMER); MercadoThe present work deals with the mechanical behaviour of a commercial AS9U3/SiCp composite formed by sand and permanent mold casting. The corresponding unreinforced matrix was also formed in the same conditions. As cast and heat treated (T6) tensile test specimens were machined and tested at room and 300° temperatures. The results showed a finer microstructure for both materials formed by permanent mold casting, with improved properties for the composite over those obtained for the unreinforced matrix, although this improvement was more clearly shown at 300°. The highest mechanical properties were obtained with the T6 heat treatment for both materials formed by permanent mold casting.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.