PRODUCTION AND CHARACTERIZATION OF AN ALUMINUM MATRIX COMPOSITE REINFORCED WITH SILICA

ARES A.E.; GREGOLIN, E.N.; SCHVEZOV, C.E.

Buenos Aires, Argentina.

Congreso; XXII INTERAMERICAN CHEMICAL ENGINEERING CONGRESS; 2006

Asociación Argentina de Ingenieros Químicos

Discontinuously reinforced MMC´s have been particularlyattractive due to the availability and cost of raw materials. The compatibilityof the reinforcement with the aluminum matrix is critical when choosingappropriate reinforcements for aluminum matrix composites, Reactionsbetween the reinforcement and the matrix can lead to a loss of mechanicalproperties of the composite during processing or after a long service time,and when the parts are exposed to high temperatures, through the formationof new phases at the interface. Another problem often found is the decreasein corrosion resistance caused by chemical interactions between thereinforcement and the matrix. In this work we analyze the production of analuminum matrix composite reinforced with silica, using commercialaluminum powder and fossil silica fibers by mixing and hot extruding thecomponents to promote an efficient metallurgical interaction between thephases and good alignment of the fibers. Also, the bars obtained were heattreated below the solidus temperature of the matrix but above the Al-Sieutectic temperature, thus inducing the formation of a metaestable siliconenriched liquid layer at the interface, increasing considerably the kinetics ofthe reaction. The liquid layer disappears at the end of the reaction or during cooling, through a difusional solidification mechanism similar to the IDF ?Infiltration Difusional Solidification process. This transformation can beaccurately controlled and used to eliminate the original discrete interfaceand to obtain a new suitable interface between the matrix and the fibers.