Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C1/00—Making non-ferrous alloys
  • C22C1/10—Alloys containing non-metals
  • C22C1/1036—Alloys containing non-metals starting from a melt
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C1/00—Making non-ferrous alloys
  • C22C1/10—Alloys containing non-metals
  • C22C1/1036—Alloys containing non-metals starting from a melt
  • C22C1/1047—Alloys containing non-metals starting from a melt by mixing and casting liquid metal matrix composites
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
  • C22C29/02—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides
  • C22C29/06—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds
  • C22C29/062—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds based on B4C
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C32/00—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ
  • C22C32/0047—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with carbides, nitrides, borides or silicides as the main non-metallic constituents
  • C22C32/0052—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with carbides, nitrides, borides or silicides as the main non-metallic constituents only carbides
  • C22C32/0057—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with carbides, nitrides, borides or silicides as the main non-metallic constituents only carbides based on B4C
• • C22C2001/1047—

Definitions

• the present invention relates to the field of the synthesis of composite materials having a metal matrix and ceramic particulate reinforcements.
• the invention relates to a method for producing a composite material having an aluminium matrix in which Al 3 B 48 C 2 reinforcements are dispersed.
• This method may in particular find an application in the aeronautical and automobile fields.
• CMMs metal matrix
• metallic matrix metal or metallic alloy
• metallic or ceramic reinforcements particles, fibres or the like
• any synthesis based on the mixing of powders of precursors of Al and B 4 C and carried out at a temperature below 1400° C. therefore leads to the decomposition of the B 4 C reinforcement by Al and to the formation of the carbide Al 3 BC 3 .
• the latter although much less sensitive to hydrolysis in the presence of moisture than the Al 4 C 3 carbide, all the same remains subject to this phenomenon, which leads to the release of large quantities of gaseous CH 4 .
• the gas produced at the core of the composite material then causes stresses that lead to the ruin of the composite material (return to the powder state).
• other phases such as the borides AlB 2 and AlB 12 may also be formed during the interaction between Al and B 4 C. The fragility of these phases then causes weakening of the composite material.
• the second solution consists of minimising the duration of the hot consolidation step in order to limit as far as possible the progress of the reaction between Al and B 4 C.
• the main difficulty lies there also in the quantity of material that can be used. This is because hot formation requires the Al matrix to be raised to a sufficient temperature to be subject to plastic deformation by creep. However, in the case of a large volume of material, making the temperature uniform throughout the whole of the volume requires also a long temperature-maintenance time.
• the inventors therefore set out to design a method for producing a composite material alternative to the Al/B 4 C composite that has properties similar to those of the Al/B 4 C composite, while being able to be carried out industrially.
• step b) when the powder is placed in the crucible in powdery form, step b) further comprises the compression of the powder.
• the compression of the powder and the closure of the cavity of the crucible are obtained by using a graphite piston.
• the piston is sized so as to be able to slide in the opening in the crucible in order to compress the powder and close off this opening.
• the crucible is heated to a temperature ranging from 1000° C. to 1400° C. for a period ranging from 5 minutes to 30 minutes.
• the temperature drop at step d) is rapid. This makes it possible to limit the decomposition reactions of the phases formed at high temperature.
• the cooling at step d) comprises a temperature drop with a rate greater than or equal to 10° C./second until 600° C. is reached.
• the removal of the crucible at step e) may be obtained by separating the ingot of composite material obtained at the end of step d) (and which forms the composite material part to be obtained) from the crucible or by carrying out a turning operation that will destroy the crucible.
• the Al/Al 3 B 48 C 2 composite material produced according to the method that is the subject matter of the invention is a good alternative to the Al/B 4 C composite material. This is because the ternary compound ⁇ 3 -Al 3 B 48 C 2 , which forms the reinforcement, is in equilibrium with the Al matrix according to the literature. Furthermore, it has properties similar to those of B 4 C, as can be noted by consulting the following table, and therefore constitutes a credible alternative to B 4 C for producing a composite with ceramic matrix and reinforcement of the boron-rich carbide type.
• the matrix and the reinforcement are formed at high temperature and in situ, which has several advantages.
• the reinforcements of the composite are obtained during the decomposition of the AlB 2 particles by germination/growth in the liquid phase.
• the matrix/reinforcement interface is therefore chemically clean (no impurities, oxides or the like) and therefore leads to optimum strength of the interface.
• the reinforcements are formed in situ and have not had to undergo a grinding cycle, a grinding that is often liable to cause defects that are then initiation points for cracking of the composite material.
• the method that is the subject matter of the invention also has the advantage of simplicity of implementation. It makes it possible in particular to obtain directly a dense ingot having the internal geometry of the graphite crucible, since the formation of the ingot is done in the liquid state in the graphite crucible.
• the single FIGURE is an image obtained by scanning electron microscopy of an ingot obtained according to a first embodiment according to the method that is the subject matter of the invention.
• the method that is the subject matter of the invention is based on a so-called reactive synthesis method. This is because the matrix and the reinforcement of the composite material are obtained in situ by a reaction between two precursors.
• the precursors chosen are aluminium diboride (AlB 2 ) and graphite (C).
• AlB 2 is in the form of a powder and is placed in a crucible that is made from graphite.
• the same graphite element preferably a graphite piston, is used for compacting the powder and for hermetically closing the cavity of the crucible.
• the whole is then raised to high temperature.
• the heating is carried out at a temperature higher than the decomposition temperature of AlB 2 , that is to say the temperature as from which there begins to be a liquid phase.
• the decomposition temperature of AlB 2 that is to say 960° C.
• the heating is carried out at a temperature of between 1000° C. and 1400° C., preferentially between 1200° C. and 1400° C., for a period which may be variable but which will generally be between 5 and 30 minutes.
• the duration of the heating at a given temperature is adjusted according to the microstructure that it is wished to obtain: the longer the heating period, the larger the size of the reinforcement particles.
• the temperature rises and falls are rapid, for the purpose of limiting both the size of the reinforcement particles and decomposition thereof during cooling.
• the graphite crucible can be eliminated by simple machining, then releasing the ingot of CMM composite material contained inside. Since the latter was obtained at a temperature higher than the melting point of Al, the presence of the matrix in the liquid state makes it possible to directly obtain a composite with a relative density greater than 99.5%.
• the microstructure of the Al/Al 3 B 48 C 2 composite thus obtained is observed under SEM (single figure).
• the white phase corresponds to the aluminium matrix and the black particles correspond to the reinforcement phase Al 3 B 48 C 2 . It can be seen that the reinforcements are dispersed in the matrix homogeneously and have a size of between 200 nm and 5 ⁇ m (mean size approximately 700 nm).
• the method that is the subject matter of the invention makes it possible to create an interface between a matrix and a reinforcement that is mechanically strong, but without leading to the decomposition of the reinforcement and to the creation of secondary phases that are detrimental to the properties of the composite. This is because, during the reactive synthesis between AlB 2 and the graphite (C), there are very few minor phases that are created and the composite therefore behaves essentially as a phase of Al (forming the matrix) and the phase of Al 3 B 48 C 2 (reinforcement), the minor phases being present in minimal quantities.
• the method according to the invention provides a novel synthesis method for producing, in a simple manner and in quantity, composite materials with an Al matrix reinforced by particles of a mixed carbide of boron (B) and aluminium (Al), the properties of which are similar to those of a B 4 C reinforcement.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Composite Materials (AREA)
• Manufacture Of Alloys Or Alloy Compounds (AREA)

Applications Claiming Priority (3)

Publications (1)

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• 2015
  • 2015-07-20 FR FR1556859A patent/FR3039169B1/fr not_active Expired - Fee Related
• 2016
  • 2016-07-19 WO PCT/EP2016/067116 patent/WO2017013087A1/fr active Application Filing
  • 2016-07-19 EP EP16741604.9A patent/EP3325681B1/fr not_active Not-in-force
  • 2016-07-19 RU RU2018106104A patent/RU2018106104A/ru not_active Application Discontinuation
  • 2016-07-19 US US15/745,927 patent/US20180209016A1/en not_active Abandoned

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