Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/71—Ceramic products containing macroscopic reinforcing agents
  • C04B35/78—Ceramic products containing macroscopic reinforcing agents containing non-metallic materials
  • C04B35/80—Fibres, filaments, whiskers, platelets, or the like
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C14/00—Glass compositions containing a non-glass component, e.g. compositions containing fibres, filaments, whiskers, platelets, or the like, dispersed in a glass matrix
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
  • C04B28/006—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing mineral polymers, e.g. geopolymers of the Davidovits type
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
  • C04B35/14—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on silica
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
  • C04B41/009—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone characterised by the material treated
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
  • C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
  • C04B41/50—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials
  • C04B41/5076—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials with masses bonded by inorganic cements
  • C04B41/5089—Silica sols, alkyl, ammonium or alkali metal silicate cements
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
  • C04B41/60—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only artificial stone
  • C04B41/61—Coating or impregnation
  • C04B41/65—Coating or impregnation with inorganic materials
  • C04B41/68—Silicic acid; Silicates
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
  • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
  • C04B2235/3201—Alkali metal oxides or oxide-forming salts thereof
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
  • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
  • C04B2235/3217—Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
  • C04B2235/34—Non-metal oxides, non-metal mixed oxides, or salts thereof that form the non-metal oxides upon heating, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
  • C04B2235/3427—Silicates other than clay, e.g. water glass
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
  • C04B2235/52—Constituents or additives characterised by their shapes
  • C04B2235/5208—Fibers
  • C04B2235/5216—Inorganic
  • C04B2235/524—Non-oxidic, e.g. borides, carbides, silicides or nitrides
  • C04B2235/5244—Silicon carbide
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
  • C04B2235/52—Constituents or additives characterised by their shapes
  • C04B2235/528—Spheres
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
  • C04B2235/96—Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
  • C04B2235/9607—Thermal properties, e.g. thermal expansion coefficient
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P40/00—Technologies relating to the processing of minerals
  • Y02P40/10—Production of cement, e.g. improving or optimising the production methods; Cement grinding

Definitions

• the invention relates to composite materials and processes for obtaining such materials, and more particularly to a thermostructural composite material comprising a fiber reinforcement and a matrix based on nano-crystalline cristobalite.
• Thermostructural composites retain their mechanical properties (tensile strength, flexion, modulus of elasticity, etc.) at a high
• thermostructural composite material according to the present invention is, by nature, also fire resistant.
• thermostructural those with a vitroceramic matrix, also called a glass matrix, and those with a CMC ceramic matrix, without oxide.
• the SiC, Si3N4 and C matrices are found.
• the material of the present invention is classified in the first category, that is to say that of the glass-ceramic matrix. But all this is just a convention. This does not imply that this matrix is made of glass.
• the thermostructural composite material comprises a matrix consisting essentially of a mineral based on nano-crystalline cristobalite as defined by its X-ray diffraction spectrum.
• the main object of the invention is the description of this matrix based on nano-crystalline cristobalite.
• a second object is the description of its method of obtaining which includes a geopolymeric synthesis of a binder of the type Potassium polysiloxonate K- (Si-O-Si-O) n
• a third object relates to the description of the composite materials thus obtained.
• the glass ceramic matrix composite materials are appreciated in the industry, in particular aeronautics and aerospace as well as in the automotive industry. These thermostructural materials would allow the realization of structures having good thermomechanical properties. Their development is envisaged for applications requiring a good behavior in continuous use (of several hundreds, or even thousands of hours) at temperatures of the order of 300 to 1000 ° C.
• this matrix must be the result of the hardening of a binder in which the size of the minerals is less than 2 microns, preferably less than 1 micron, to ensure perfect impregnation between the fibers.
• the matrix then contains a nano-crystalline cristobalite, the geopolymeric particles or micelles of which are smaller than 1 micron, preferably less than 500 nanometers. This is the main object of the present invention.
• the glass-ceramic matrix composite materials are generally referred to as silica-based.
• silica-based This does not mean that the glass-ceramic matrix is essentially composed of silica S1O2, as is the case for special composites containing vitreous silica, especially those used to manufacture radomes transparent to radar waves.
• these silica-based matrices indicate that they contain silicon Si, in the form of lithium aluminosilicate (LAS), LiO2.Al2O3.SiO2,
• magnesium aluminosilicate (MAS), MgO.Al2O3.SiO2, barium salt aluminosilicate (BAS), BaO.Al 2 O 3 .SiO 2 , calcium aluminosilicate (CAS),
• Table 1 SiO 2 % by weight in the vitroceramic matrices of the prior art (LAS), LiO2.Al2O3.SiO2 31, 2%
• patent EP 0404632 claims a glass-ceramic matrix in which this amount of silica S102 is between 25 and 70%, the glass-ceramic matrix consisting essentially of aluminosilicate containing alkaline earth oxides and rare earth oxides.
• the term glass ceramic matrix to Silica base is correct since the amount of SiO 2 is greater than 85% by weight of the matrix.
• the matrix according to the invention is based on nano-crystalline cristobalite containing essentially at least 85% by weight of silica.
• the method of manufacturing the thermostructural composite material requires densification at a temperature of at least 850 ° C, preferably between 900 ° C and 1100 ° C, all under one embodiment. isostatic pressure of at least 3 MPa, for several hours, followed by another heat treatment between 1100 ° C and 1200 ° C, or even 1350 ° C.
• patent application WO 2005/030662 describes a method for manufacturing a lithium aluminosilicate (LAS) glass-ceramic matrix in which the densification temperature is carried out at a significantly lower temperature, around 500 ° C. .
• the so-called sol-gel impregnation technique is used for this purpose.
• the manufacturing method follows the technology developed for the geopolymer matrices, that is to say by means of a densification (a polycondensation) carried out at a temperature below 200 ° C. under vacuum cover in autoclave.
• the potassium polysiloxonate K- (Si-O-Si-O) n type geopolymeric compound is used.
• a short heat treatment is applied to this geopolymeric matrix at a temperature of 700 ° C., without exerting pressure, it crystallizes in the form of a mineral based on nano-crystalline cristobalite as defined by its diffraction spectrum.
• a fluoroaluminosilicate geopolymeric binder described in patent FR 2,659,320 is also known.
• This binder can be used, inter alia, to impregnate fiber reinforcements. It comprises a poly (sialate-siloxo) fluoropolymer (MF) -PSDS type geopolymer accompanied by an alkaline aluminum fluoride, cryolite Na 3 AIF 6 or elpasolite K 2 NaAIF 6 , and a siliceous phase of Opal type.
• CT ie hydrated silica. The amount of this siliceous phase can vary between 10 and 95 parts by weight of the geopolymeric binder. As we can read in the
• this siliceous phase confers dilatometric properties in temperature, quite particular. For example, line 22-23 on page 4 states that it is not crystalline cristobalite, although this Opal CT silica phase has a characteristic dilatometric curve of SiO 2 in the cristobalite phase.
• crystalline cristobalite has this dilatometric behavior, namely, a high expansion of 0 to 210 ° C, of the order of 15. 0 6 / ° C and, after the offset to 200 -210 ° C, a small expansion of the order of 2 to 5.
• 10 "6 / ° C. This is the first dilatometric phase, the one with high expansion which is claimed in patent FR 2 659 320.
• This expansion is essentially depending on the amount of SiO 2 silica of the Opal CT type.
• the coefficient is less than ⁇ . ⁇ ⁇ ⁇ /.
• For 26 to 75 parts of Opal CT it is between 10.10 "6 and 20.10 " 6 / ° C and for 76 to 95 parts of Opal CT, it is greater than 20.10 "6 / ° C.
• the matrix is formed of a nano-crystalline cristobalite-based mineral as defined by its X-ray diffraction spectrum. It is not made entirely of Opal CT hydrated silica. X-ray amorphous, but on the contrary, its diffraction spectrum is extremely precise and well characterized crystalline cristobalite. In the context of the invention it is even nanocrystalline, that is to say composed of nanocrystals of dimensions less than 1 micron, preferably less than 500 nanometers.
• thermostructural composite material It is also known that the fiber-reinforced composite made using the geopolymeric matrix of (F, M) -PSDS type of the patent FR 2 659 320 does not meet the definition given above for the thermostructural composite material. Obviously, like all geopolymer matrices, it is fire resistant, but its use is limited to average temperatures, generally below 500 ° C.
• thermostructural composite material comprising a fiber reinforcement and a nano-crystalline cristobalite matrix according to the present invention does not contain cryolite or elpasolite.
• its X-ray diffraction spectrum only describes cristobalite with its main 2-theta crystallographic planes 21, 9 (hkl 101), 31, 4 (hkl 102), 36.4 (hkl 200), for CuKal radiation It can be used continuously, at temperatures above 500 ° C, up to 1000 ° C, without undergoing significant degradation or loss of mechanical strength throughout the duration of its operation.
• the operating temperatures are essentially determined by the nature of the reinforcing fibers containing at least one of the Si, B, O, N and C elements. Those skilled in the art know that in the case of carbon fiber , we avoid the
• the diatomaceous earth is composed of hydrated amorphous silica which is industrially heat treated at a temperature above 900 ° C., most often above 1000 ° C.
• Calcined diatomaceous earth used in the production of filters for the food industry, is obtained which contains between 40 and 60% by weight of crystalline cristobalite, the size of which is generally greater than 2 microns.
• This cristobalitic diatom could be used to manufacture a thermostructural composite material comprising a fiber reinforcement and a matrix based on nano-crystalline cristobalite, by impregnating the fibrous reinforcement with a mineral binder (for example a geopolymer binder) containing a size cristobalite. very small. For this, it should be grinded very finely, at least below 2 microns, preferably below 1 micron, or employ a manufacturing process that would avoid any agglomeration of siliceous skeletons smaller than 2 microns.
• WO 88/02741 indicates that in the case of a geopolymeric ceramic matrix composite material, the dimension of the charges must be less than 2 microns. Now it is very difficult and very expensive to achieve a grain size of this type by simple grinding, and therefore, to the knowledge of the applicant, we can not achieve the object of the invention by this method.
• EP 1996/0903002 describes the manufacture of a silica glass containing cristobalite particles of size between 0.1 microns and 1000 microns.
• the size of the cristobalite particles is never less than 40 microns.
• the final product is a solid silica glass that will have to be milled to a size of less than 2 microns, as in the case of the calcined diatom, mentioned above.
• the method of manufacturing cristobalite passes through the melting phase, that is to say involves temperatures between 1630 ° C and 1720 ° C.
• the nano-crystalline cristobalite-based mineral is crystallized at a much lower temperature, higher than 500 ° C, preferably between 600 and 800 ° C.
• cristobalite is produced starting from an amorphous silica gel to which doping products are added: Al, Na, Sr, K, Ca.
• the temperature of the transformation into cristobalite is at least 1000 ° C, for 24 hours.
• Si: AI.Ca system it is 8 hours at 1100 ° C.
• Si: AI: K system it takes at least 24 hours at 1100 ° C.
• the Si: Al: K system is the preferred one in the examples of the present invention which, unlike the prior art, produces nano-crystalline cristobalite at a temperature well below 1100 ° C, only between 500 ° C. and 800 ° C.
• the crystallization time is very short since at 700 ° C it is only 10 to 15 minutes.
• the aluminosilicate matrix requires extremely long crystallization times, at least 24 hours and contains less than 80% by weight silica oxide S102.
• the matrix is present in the form of micelles and / or microspheres of dimensions less than 1 micron, preferably less than 500 nanometers.
• the said micelles and / or microspheres are interconnected by an amorphous alveolated phase consisting of closed cells.
• the scientific article by Zhu et al. sets forth the rules for obtaining a nano-crystalline cristobalite (see Y. Zhu, K. Yanagisawa, A. Onda and K. Kajiyoshi, "The preparation of nano-crystallized cristobalite under hydrothermal conditions" Journal of Materials Science, 40, 3829
• the starting material is a colloidal silica, a silica gel, whose micelle size (particles) is of the order of 18-20 nanometers.
• Nano-crystalline cristobalite is carried out at average temperatures between 200 ° C and 400 ° C, but it depends solely on the nature of the alkaline salts and the alkaline solutions used during the experiment. It reveals that cristobalite is only formed with the alkaline salts NaF and KF (with a preference for NaF), but that, on the other hand, the action of NaOH always leads to the formation of quartz. However, the presence of the NaF and KF alkaline salts prevents this nano-crystalline cristobalite from forming a matrix having thermostructural properties. In fact, these alkaline salts act as fluxing agents which, at higher temperatures, will transform the matrix into glass. We then find us in the same unfavorable practical conditions at high temperature as those encountered for geopolymer binders of (M, F) -PSDS type, mentioned above in the patent FR 2 659 320.
• the method according to the invention is characterized in that the matrix nano-crystalline cristobalite base results from the crystallization of a geopolymeric micelle of potassium polysiloxonate K- (Si-O-Si-O) n , by action of potassium hydroxide KOH, which seems contrary to the teaching provided by the prior art.
• the geopolymeric synthesis of the matrix is carried out at a temperature below 200 ° C., followed by a heat treatment at a temperature above 500 ° C. preferably between 600 ° C and 800 ° C.
• quartz is always formed.
• the nano-crystalline cristobalite matrix is in the form of micelles and / or microspheres of dimensions less than 1 micron, preferably less than 500 nanometers.
• This nano-crystalline cristobalite matrix of the present invention enables the manufacture of a thermostructural composite material comprising a fiber reinforcement. It contains, apart from oxygen and carbon, the following principal elements: Si, K, Al, Zr, of which at least 75 per cent by weight of Si atom. These principal elements are those which, in the elemental analysis of the matrix under an electron microscope are present at more than 0.2% by weight of atom.
• the chemical composition of said matrix contains at least 85% by weight of oxide SiO 2 , at most 3% by weight of Al 2 O 3 , at most 10% by weight of K 2 O, at most 4% by weight of ZrO 2 .
• the absence of formative agents or glass modifiers is found as claimed in the WO application.
• thermostructural composite material contains at least one of the elements Si, B, O, N and C.
• amount of nano-crystalline cristobalite matrix is between 40 and 70, preferably between 45 and 55 percent of the total weight of said composite material.
• Geopolymer matrices of the K-nano-poly (siloxo) or K-nano-poly (sialate) type are already known in the prior art. They are described in the book Geopolymer, Green Chemistry and Sustainable Development Solutions, Proceedings of the World Geopolymer Congress 2005, edited by Joseph Davidovits, Institute
• Geopolymer (Geopolymer Institute) ISBN 2-9514820-0-0 (2005), pages 1-12, as well as in the book already cited above, Geopolymer Chemistry & Applications, in Chapter 1 1, Section 1 1.6, entitled Poly ( siloxo) and poly (sialate) cross-links, nacocomposite geopolymer.
• the nano-composite geopolymer is defined in that it comprises two phases:
• a nodular phase of silica fume composed of nanospheres of diameter less than 1 micron, preferably less than 500 nanometers.
• optical microscope consisting of poly (silanol) linear chains more or less crosslinked by a siloxo bridge (-Si-O-Si-O-), or a sialate bridge (Si-O-AI-O-).
• the method for manufacturing the glass-ceramic matrix of the nano-crystalline cristobalite type first comprises the synthesis, according to the methods already described above, of a compound based on nano-poly (siloxo) type geopolymeric micelles.
• this compound in its more precise form of potassium polysiloxonate, K- (Si-O-Si-O) n . It contains at least 85% by weight of amorphous silica S1O2 with not more than 15%, preferably not more than 10% by weight, of potassium oxide K 2 O. As can be seen, even after treatment at 500 ° C.
• the matrix presents at least one of the
• the spectrum 29SINMR is different since it is essentially that of cristobalite, consisting of SiO 2 Si (Q 4 ), with a single major resonance at -109 ppm (see in the book: High Resolution Solid-State NMR of Silicates and Zeolites, by G. Engelhardt and D. Michel, John Willey & Sons, 1987, page 170 Silica
• the matrix according to the invention is characterized in that it contains a mineral based on nano-crystalline cristobalite which results from the crystallization of geopolymeric micelles of potassium polysiloxonate. These are obtained by geopolymeric synthesis at a temperature below 200 ° C.
• the matrix is then subjected to a heat treatment at a temperature above 500 ° C., preferably between 600 ° C. and 800 ° C.
• the nano-crystalline cristobalite is in the form of micelles and / or microspheres of dimensions less than 1 micron, preferably less than 500 nanometers, interconnected by an amorphous phase. This amorphous phase may also be weakly cellular, consisting mainly of closed cells.
• the whole forms the matrix based on nano-crystalline cristobalite as defined by its X-ray diffraction spectrum with the three main lines with 2 theta 21, 9 (hkl 101), 31, 4 (hkl 102), 36, 4 (hkl 200), for CuKal radiation.
• the X-ray diffraction spectrum is also accompanied by a 21-degree 2-theta line that can be attributed to tridymite (hkl 100).
• the nano-crystalline cristobalite matrices according to the present invention are generally employed in the manufacture of fibrous reinforcing composites for use at high temperature, in the range of 300 ° C to 1000 ° C, continuously, during hundreds or thousands of hours.
• the temperatures of use are essentially determined by the nature of the reinforcing fibers containing at least one of Si, B, O, N and C. Those skilled in the art know that in the case of carbon fiber, avoids the degradation thereof by working in a non-oxidizing atmosphere.
• the amount of nano-crystalline cristobalite matrix is from 40 to 70, preferably from 45 to 55 percent of the total weight of said composite material. Its linear expansion coefficient is ⁇ > W 0 / ° C from 0 ° C to 210 ° C and then ⁇ ⁇ 6.10 "6 / ° ⁇ above 210 ° C
• these matrices can also be used in the manufacture of ceramic objects containing well-referenced mineral fillers.
• the fiber is first impregnated with a potassium polysiloxonate K- (Si-O-Si-O) n geopolymer binder, and the geopolymeric synthesis is then carried out. autoclaving at 200 ° C. Finally, the composite material thus produced is subjected to a heat treatment at a temperature above 500 ° C, preferably between 600 ° C and 800 ° C, for a relatively short time between 10 minutes and 30 minutes.
• the composite material contains the thermostructural matrix consisting essentially of a mineral based on nano-crystalline cristobalite as defined by its X-ray diffraction spectrum, namely the three main lines with 2 theta 21, 9 (hkl 101), 31, 4 (hkl 102), 36.4 (hkl 200), for CuKa radiation
• the starting raw material is amorphous silica consisting of amorphous particles smaller than 1 micron, preferably less than 500 nanometers.
• amorphous silica consisting of amorphous particles smaller than 1 micron, preferably less than 500 nanometers.
• nano-crystalline cristobalite matrix for thermostructural fibrous composite material of the present invention is illustrated by the following examples. They do not have a limiting character on the overall scope of the invention as presented in the claims.
• K 2 O comes from potassium silicate. The ratio between the oxides is:
• nano-poly (siloxo) geopolymer as a function of temperature up to 500 ° C.
• the oven temperature increases by 10 ° C per minute and a plateau is set at 500 ° C for 30 minutes before allowing to cool.
• the X-ray pattern is amorphous. There is no crystallization of quartz as should have been the case according to the article by Zhu et al. described above. There is also no cristobalite. However, accidentally, the heat treatment was continued up to 750 ° C, with a plateau at 750 ° C for 15 minutes. The X-ray diffraction pattern then shows the lines very
• the geopolymeric synthesis of a potassium polysiloxonate K- (Si-O-Si-O) n is carried out by reacting silica fume from the electrofusion at 2000 ° C of a natural silicate with carbon dioxide.
• SiO 2 comes from silica fume
• K 2 O and H 2 O come from an aqueous solution of KOH.
• the ratio between the oxides is:
• geopolymer potassium polysiloxonate as a function of temperature, up to 750 ° C, as in Example 1. It is confirmed that at 500 ° C, the X-ray pattern is amorphous. But after the heat treatment at 750 ° C. for 15 minutes, the X-ray diffraction pattern then shows the very characteristic lines of cristobalite with three main lines with 2 theta 21, 9 (hkl 101), 31, 4 (hkl 102), 36.4 (hkl 200), for the CuKal radiation In addition, the
• the geopolymer has undergone a very small expansion of less than 3% by volume.
• the geopolymeric synthesis is repeated according to Example 2, but replacing the potassium hydroxide with sodium hydroxide NaOH. After the heat treatment at 750 ° C, the X-ray diffraction pattern remains amorphous. The nano-crystalline cristobalite phase did not develop.
• the geopolymeric synthesis is repeated according to Example 2, but replacing the silica fume by colloidal silica type Ludox or equivalent.
• the evolution of the potassium polysiloxonate geopolymer as a function of temperature is followed, up to 750 ° C., as in Example 1. It is confirmed that, at 500 ° C., the X-ray is amorphous.
• the X-ray diffraction pattern shows the very characteristic lines of cristobalite with three main lines with 2 theta 21, 9 (hkl 101), 31, 4 (hkl 102), 36.4 (hkl 200),
• the geopolymer has undergone very little expansion, less than 3% by volume.
• a geopolymeric mixture is carried out according to Example 2 to serve as a matrix for a thermostable composite material.
• various ingredients known in the prior art are added to the geopolymeric mixture to facilitate the impregnation and to modify the rheology of the binders resulting from geopolymeric synthesis and traditional alkaline silicates.
• examples include wetting agents and surface tension modifiers, usable in strongly alkaline medium; also other organic products such as polyols and polyglycols (soluble in alkaline medium), generally used as adjuvants in very small amounts, generally less than 2% by weight of the matrix.
• SiC silicon carbide fiber
• the mixture is evacuated for 1 hour at ambient temperature, and the complex is then placed in an autoclave at 120 ° C. under 6 bars of pressure for 3 hours.
• the plates are removed and subjected to heat treatment at 750 ° C. for 15 minutes.
• the sample is placed in the oven at 20 ° C. and the temperature is raised at a rate of 10 ° per minute, and then, when the 750 ° C. are reached, a plateau of 15 minutes is reached. Then, let cool in the oven.
• the examination of the X-ray diffraction spectrum of the matrix shows the three main lines with 2 theta 21, 9 (hkl 101), 31, 4 (hkl 102), 36.4 (hkl 200), for the CuKal radiation.
• the X-ray diffraction spectrum is also accompanied by a 2-theta 21-degree line attributed to tridymite (hkl 100).
• the nano-crystalline cristobalite matrix weight ratio and SiC fiber weight is 49/51.
• a sample of this composite material is subjected to various analyzes, namely: a) elementary chemical analysis of the matrix, by electron microscopy, in% by weight of the matrix:
• the composite material thus produced has a flexural strength of 158 MPa at 20 ° C; this is maintained at 142 MPa after 100 hours at 700 ° C. and is still at 124 MPa after 1000 hours at 700 ° C.
• a composite material is produced according to Example 5, but the source of SiO 2 consists of silica fume (see Example 2) and colloidal silica (see Example 4) in a 50/50 ratio by weight of SiO 2 .
• the nanocrystalline cristobalite matrix is obtained and the weight ratio of matrix and weight of SiC fiber is 48/52.
• a sample of this composite material is subjected to elemental chemical analysis of the matrix, by electron microscopy, in% by weight of the matrix:

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Structural Engineering (AREA)
• Inorganic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Manufacturing & Machinery (AREA)
• Geochemistry & Mineralogy (AREA)
• Life Sciences & Earth Sciences (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geology (AREA)
• Environmental & Geological Engineering (AREA)
• Dispersion Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Silicon Compounds (AREA)
• Glass Compositions (AREA)
• Inorganic Fibers (AREA)
• Civil Engineering (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=43033429

Family Applications (1)

Country Status (4)

Families Citing this family (2)

Family Cites Families (17)

• 2010
  • 2010-04-14 FR FR1001582A patent/FR2958934A1/fr not_active Withdrawn
• 2011
  • 2011-03-28 EP EP11732501A patent/EP2558430A1/de not_active Ceased
  • 2011-03-28 US US13/640,365 patent/US8975201B2/en active Active
  • 2011-03-28 WO PCT/FR2011/000185 patent/WO2011128521A1/fr active Application Filing

Non-Patent Citations (2)

Also Published As

Similar Documents

Legal Events