Reference : Interfacial phenomena in carbon fibre reinforced magnesium alloys processed by squeeze c...
Scientific congresses and symposiums : Unpublished conference
Engineering, computing & technology : Materials science & engineering
Interfacial phenomena in carbon fibre reinforced magnesium alloys processed by squeeze casting and thixomolding
[fr] Phénomènes interfaciaux dans les alliages de magnésium renforcés par des fibres de carbone élaborés par forgeage liquide et thixoformage
Montrieux, Henri-Michel mailto [Université de Liège - ULg > Département d'aérospatiale et mécanique > Science des matériaux métalliques >]
Mertens, Anne mailto [Université Catholique de Louvain (UCL) > Institute of Mechanics, Materials and Civil Engineering > > >]
Halleux, Jacques mailto [> >]
Delannay, Francis mailto [> >]
Lecomte-Beckers, Jacqueline mailto [Université de Liège - ULg > Département d'aérospatiale et mécanique > Science des matériaux métalliques >]
Euromat 2011: European Congress and Exhibition on Advanced Materials and Processes
du 12 au 15 septembre 2011
Société Française de Métallurgie et de Matériaux
Associazione Italiana di Metallurgia
[en] carbon ; metal matrix composites ; interfaces ; magnesium ; squeeze casting ; thixomolding ; AZ91 ; reactive wetting ; contact angle
[en] Composite materials are known to combine interesting properties of different materials. This research concerns magnesium alloys reinforced by carbon fibre weaves. Such a material can theoretically exhibit a high yield strength/density ratio. This composite is thought to be especially promising for aeronautics. A pre-treatment of carbon weaves ensure two fundamental functions. The first is to provide stiffness and cohesion. It helps keeping fibres aligned and well placed in the mould during casting to ensure optimal
properties of the final part in the main load directions. This is imperative when the composite is
formed with thixomolding for which semi liquid metal is injected with a very high speed. Nevertheless the problem of geometrical carbon weaves stability is also encountered with squeeze casting. The second objective of the pre-treatment is to provide a porous network in the weaves to enhance infiltration by the capillary action. The two functions can be assumed by coating fibres with Al(H2PO4)3, SiO2 combined with starch, or some other oxide containing mixtures. The general process is to assemble carbon weaves, infiltrate them in an aqueous solution or dispersion of oxides and lastly heat them at high temperature to promote covalent bonds with fibres and vaporize or crack carbonaceous agents to let a porous medium.
Further the chemical interaction between the coated fibres and the liquid metal during infiltration
can influence the species which are present at the interfaces. As magnesium oxide is stable magnesium can react with oxides. This could lead to better wettability of treated weave. However such chemical reactions seem to be thermally activated and take many seconds to initiate, whereas solidification of magnesium is achieved faster. Furthermore the addition of some carbide former elements (Si, Ti, Zr) to a
magnesium based alloy can also influence chemical affinity. In conclusion CMg-MMC research concerns composites with low density, high potential mechanical properties and possibility of processing through thixomolding. Firstly the reach of the theoretical performance of the composite includes the ability of dealing with the interaction between fibres and liquid metal. Secondly primary treatment could help to form bonds between matrix and fibres, make rigid weaves and promote a further infiltration. Thirdly chemical affinity between the fibres, magnesium alloy and coating can influence the infiltration.
Science des matériaux métalliques (MMS Unit)
Région wallonne : Direction générale des Technologies, de la Recherche et de l'Energie - DGTRE
Développement d'une ailette d'obus en magnésium renforcée de fibres de carbone
Researchers ; Professionals ; Students

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