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AssigneeFreni Brembo S.p.A.
InventorsRalf Siegfried Goller, Giovanni Paolo Pacchiana
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A shaped composite material for braking applications can be produced by a method comprising the steps of: a) providing a mixture comprising bundles of filaments constituted substantially by carbon and having lengths no greater than 30 mm and an organic binder in a mould of the said shape and, at the same time, incorporating in the mixture a plurality of reinforcing fibres which extend along the shape in a manner such as to prevent the propagation of cracks, b) forming the mixture comprising the reinforcing fibres to produce a semi-finished product, c) subjecting the semi-finished product to a first firing at a temperature such as substantially to bring about pyrolysis of the organic binder and to a second firing in the presence of silicon.
A method of producing a shaped composite material, comprising the steps of:
A method according to any one of the preceding claims, in which the bundles of filaments and/or the reinforcing fibres are coated with a resin.
A method according to any one of the preceding claims, in which the quantity of bundles of filaments in the mixture is within the range of 50-80% by volume, relative to the volume of the mixture.
A method according to any one of the preceding claims, in which the quantity of organic binder in the mixture is within the range of 5-30% by volume, relative to the volume of the mixture.
A method according to any one of the preceding claims, in which the mixture further comprises from 0.7% to 23% by volume, relative to the volume of the mixture, of additives selected from the group comprising graphite, silicon carbide and metal carbides and nitrides, in powder form.
A method according to any one of the preceding claims, in which the reinforcing fibres are selected from the group comprising carbon fibres and metal fibres.
A method according to any one of the preceding claims, in which the forming step is performed at a temperature of 80-180° C. with the application of a pressure of 0.1-5N/cm2 to the mixture comprising the reinforcing fibres.
A method according to any one of the preceding claims, in which the first firing of the semi-finished product is performed at a temperature of 900-1200° C., in the presence of an inert gas.
A method according to any one of the preceding claims, in which the second firing of the semi-finished product is performed in the presence of an inert gas, at a temperature of 1400-1700° C. and under partial vacuum with a reduced pressure of from 300 to 900 mbars.
A method according to any one of the preceding claims, further comprising a step for dry finishing of the semi-finished product, performed after the first firing of step d) and before the second firing of step e).
A method according to any one of the preceding claims, further comprising a step for dry or wet finishing of the semi-finished product, performed after the second firing of step e).
A shaped composite material obtainable by providing a mixture comprising bundles of filaments, arranged randomly and having dimension no greater than 30 mm, a plurality of reinforcing fibres which extends along the shape of the material in a manner such as to prevent the propagation of cracks, and an organic binder, said binder made porous by pyrolysis of the mixture, and causing said mixture to interact with molten silicon, wherein said bundles of filaments and said reinforcing fibres in said composite material as obtained by said step of interaction with silicon are constituted substantially by carbon.
Dependencies are inferred from the claim text.