PARTICULATE COMPOSITE CERAMIC MATERIAL, PART COMPRISING SAID MATERIAL, AND METHOD FOR THE PREPARATION OF SAID PART

Abstract

A particulate composite ceramic material comprising: particles of at least one first ultra-high-temperature ceramic UHTC, the outer surface of said particles being at least partially covered by a porous layer made of at least one second ultra-high-temperature ceramic in amorphous form; and the particles defining a space therebetween; optionally, porous clusters of said at least one second ultra-high-temperature ceramic in amorphous form, distributed in said space; a dense matrix and at least one third ultra-high-temperature ceramic in crystallized form at least partially filling said space; optionally, a dense coating made of at least said third ultra-high-temperature ceramic in crystallized form, covering the outer surface of said matrix, said matrix and said coating representing 5% to 90% by mass with respect to the total mass of the material.

Part comprising said particulate ceramic composite material.

Method for manufacturing said part.

Claims

1-21. (canceled)

22: A particulate composite ceramic material, comprising: particles comprising at least one first ultra-high-temperature ceramic (UHTC) in crystallised form, the outer surface of said particles being at least partially covered by a porous layer comprising at least one second ultra-high-temperature ceramic in amorphous form, said first ultra-high-temperature ceramic (UHTC) in crystallised form representing 25% to 90% by mass with respect to the mass of the material and said second ultra-high-temperature ceramic in amorphous form representing 2% to 15% by mass with respect to the total mass of the material, and the particles defining a space therebetween; optionally, porous clusters of said at least one second ultra-high-temperature ceramic in amorphous form, distributed in said space; a dense matrix comprising at least one third ultra-high-temperature ceramic in crystallised form at least partially filling said space; optionally, a dense coating comprising at least said third ultra-high-temperature ceramic in crystallised form, covering the outer surface of said matrix, said matrix and said coating representing 5% to 90% by mass with respect to the total mass of the material, the porosity of said porous layer comprising at least one second ultra-high-temperature ceramic in amorphous form being 15% to 30%.

23: The material according to claim 22, which has an overall porosity greater than or equal to 5%.

24: The material according to claim 22, wherein the porous layer comprising at least one second ultra-high-temperature ceramic in amorphous form has a thickness of 0.1 to 1 micron.

25: The material according to claim 22, wherein said first, second and third ceramics are selected from the group consisting of boride ceramics, carbide ceramics, nitride ceramics, silicide ceramics, carbon, and mixtures thereof.

26: The material according to claim 25, wherein said first, second and third ceramics are selected from the group consisting of SiC, MoSi.sub.2, TiC, TaC, ZrC, ZrB.sub.2, HfC, HfB.sub.2, BN, AlN, TiN, carbon, and mixtures thereof.

27: The material according to claim 22, wherein said first, second and third ceramics are identical.

28: The material according to claim 27, wherein said first, second and third ceramics are SiC.

29: The material according to claim 28, wherein the first ultra-high-temperature ceramic is SiC in a crystallised form, the second ceramic is amorphous porous SiC, and the third ceramic is SiC in crystallised form.

30: A part, comprising the particulate composite ceramic material according to claim 22.

31: The part according to claim 30, which constitutes all or part of a heat exchanger, of a catalysts support, of a filter operating in a corrosive atmosphere and/or at a high temperature, of a furnace part or of a furnace, of a heating resistor, of a combustion chamber, of a varistor, of a substrate for power components, of a shielding, of a rolling component, or of an abrasive coating.

32: A method for manufacturing a part according to claim 30, comprising the following successive steps: a) preparing a raw or green part, comprising a mixture of a powder of particles of the first ceramic and of a powder of particles of a refractory pore-forming material capable of being eliminated by a chemical attack, a precursor polymer of the second ceramic, and a solvent of said polymer; b) evaporating the solvent and crosslinking the precursor polymer of the second ceramic; c) performing a heat treatment to transform the polymer into the second ceramic, which is in the form of a porous layer that at least partially covers the outer surface of the particles of the first ceramic, and optionally of porous clusters; d) eliminating the refractory pore-forming material by a chemical attack, whereby a part is obtained comprising the particles of the first ceramic, the second porous ceramic that is in the form of a porous layer that at least partially covers the outer surface of said particles and optionally of porous clusters, and an internal porosity between said particles; e) treating the part obtained at the end of step d) by a chemical vapour infiltration (CVI) technique in order to deposit the third ceramic in the internal porosity of the part; and f) optionally, depositing the third ceramic on the outer surface of the part obtained at the end of step e) by a chemical vapour deposition (CVD) technique.

33: The method according to claim 32, wherein step a) during which a raw or green part is prepared comprises a step of preparing the mixture of a powder of particles of the first ceramic and of a powder of particles of the refractory pore-forming material capable of being eliminated by a chemical attack; and a step of forming, shaping the mixture of a powder of particles of the first ceramic, and of a powder of particles of the refractory pore-forming material capable of being eliminated by a chemical attack, in the form shape, of the raw or green part.

34: The method according to claim 32, wherein the refractory pore-forming material is selected from materials capable of withstanding a temperature greater than 300 C.

35: The method according to claim 34, wherein the refractory pore-forming material is selected from the group consisting of plaster, potassium carbonate, calcium carbonate, and potassium sulphate (K.sub.2SO.sub.4).

36: The method according to claim 32, wherein the preparation of the mixture of the powder of particles of the first ceramic, and of the powder of particles of the refractory pore-forming material capable of being eliminated by a chemical attack is carried out by a dry process or by a wet process.

37: The method according to claim 32, wherein the forming, shaping of the mixture of a powder of particles of the first ceramic, and of a powder of particles of the refractory pore-forming material capable of being eliminated by a chemical attack is carried out by moulding, by slip casting, with a filter press, or by an addictive manufacturing technique.

38: The method according to claim 32, wherein the precursor polymer of the second ceramic, is added during the step of preparing the mixture of a powder of particles of the first ceramic, and of a powder of the refractory pore-forming material capable of being eliminated by a chemical attack; or during the step of forming, shaping the mixture of a powder of particles of the first ceramic, and of a powder of particles of the refractory pore-forming material capable of being eliminated by a chemical attack; or after the step of forming, shaping the mixture of a powder of particles of the first ceramic and of a powder of particles of the refractory pore-forming material capable of being eliminated by a chemical attack, in the form, shape of a raw or green part.

39: The method according to claim 32, wherein the precursor polymer (pre-ceramic polymer) of the second ceramic is selected from the group consisting of polycarbosilanes, poly silazanes, polyborosilanes and mixtures thereof.

40: The method according to claim 32, wherein steps b) and c) are grouped.

41: The method according to claim 32, wherein during step c) the heat treatment is carried out at a temperature of 600 C. to 1600 C.

42: The method according to claim 32, wherein, during step d), the chemical attack is performed with a solution of an acid.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0188] FIG. 1 shows the raw, green, part, with lattice structure prepared in Example 1.

[0189] FIG. 2 shows the digital model of the lattice structure of FIG. 1. Said digital model has been created with CAD software.

[0190] FIG. 3 shows the final part made of SiC obtained in Example 1.

[0191] FIG. 4 is a photograph taken in optical microscopy that shows the microstructure of the material constituting the part obtained after the souring step in Example 1.

[0192] The scale shown in FIG. 4 represents 20 m.

[0193] FIG. 5 is a photograph taken in scanning electron microscopy (SEM) that shows the microstructure of the material constituting the part obtained after the souring step in Example 1.

[0194] The scale shown in FIG. 5 represents 10 m.

[0195] FIG. 6 is a photograph taken in optical microscopy that shows the microstructure of the material constituting the final part obtained in Example 1.

[0196] The scale shown in FIG. 6 represents 20 m.

[0197] FIG. 7 is a photograph taken in scanning electron microscopy (SEM) that shows the microstructure of the material constituting the final part obtained in Example 1.

[0198] The scale shown in FIG. 7 represents 10 m.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

[0199] The invention will now be described with reference to the following examples, given for illustrative and non-limiting purposes.

Example 1

[0200] Production of a Part with Lattice Structure Made of SiC, Formed, Shaped by Additive Manufacturing.

[0201] In this example, a lattice structure made of SiC, which is formed by additive manufacturing, is manufactured by the method according to the invention.

[0202] First of all, a mixture of a plaster powder and of a SiC powder is prepared.

[0203] The SiC powder is mixed with the plaster powder, in the proportions of 70% by mass of SiC, and of 30% mass of plaster.

[0204] The SiC powder is available from Sigma Aldrich, under the reference 357391, the SiC powder has a particle size of 400 mesh.

[0205] The plaster powder is available from 3D System, under the reference ZP 151. It is in fact according to the technical data sheet a High Performance Composite that is to say plaster with a few additives.

[0206] The mixture is performed by dry process, in a plastic bottle of 1 L, shaken using a so-called turbulat powder mixer available from Bioengineering of 80 W power. The mixture is performed at 20 revolutions/min.

[0207] A raw green part with lattice structure is printed by additive manufacturing, using a Z-Printer 310 printer available from Z Corporation.

[0208] In order to imprint said part with lattice structure, the powder mixture previously prepared is used, placed in suspension in the Pro-1 colourless binder available from 3D Systems, in the printhead of the printer.

[0209] The digital model of the lattice structure is shown in FIG. 2, it has been created with CAD software.

[0210] The printing is performed with standard printing parameters, namely with a layer thickness of 100 microns, a printing speed of 20 mm/h along the z-axis (that is to say the vertical axis with respect to the building tray). The part is recovered after drying at 120 C. in the oven.

[0211] FIG. 1 shows the raw, green, part, with lattice structure obtained. Said part consists of a mixture of plaster, of SiC and of binder.

[0212] The lattice has ligaments of 1.3 mm of diameter, the dimension of the cells is 5 mm5 mm5 mm, and the number of cells is 216 (666).

[0213] The raw, green, part is then placed on a support, and the part is immerged into a mixture of 65% by mass of polycarbosilane (compound available from Starfire Systems under the name StarPCS SMP-10) and of 35% by mass of toluene, in an enclosure under vacuum.

[0214] The part is then removed from the enclosure and dried in an oven at 250 C., then treated at 1000 C. for 1 h under inert gas.

[0215] The part obtained consists of 45% by mass of SiC from the polycarbosilane polymer.

[0216] The part is then placed in a solution of concentrated hydrochloric acid (37%), at 60 C., for 2 hours, in order to eliminate the plaster by decomposition and dissolution. Said step is called souring step.

[0217] The part is subsequently washed with water then dried.

[0218] FIG. 4 is a photograph taken in optical microscopy that shows the microstructure of the material constituting the part obtained after the souring step, the washing with water, and the drying.

[0219] FIG. 5 is a photograph taken in scanning electron microscopy (SEM) that shows the microstructure of the material constituting the part obtained after the souring step, the washing with water, and the drying.

[0220] FIGS. 4 and 5 show: [0221] [1] SiC grains; [0222] [2] amorphous SiC from the polymer; [0223] [3] a porosity.

[0224] Finally, the part is placed in a CVI furnace with the following infiltration conditions: temperature approximately 1050 C., pressure 10 kPa, ratio of the [H.sub.2]/[CH.sub.3SiCl.sub.3] gas flow rates=5, duration 24 h.

[0225] After the densification, the part consists of 17% by mass of SiC from the polymer, of 21% by mass of particulate SiC and of 62% by mass of SiC deposited by CVI. The average density of the ligaments is 2.5 g/cm.sup.3.

[0226] FIG. 3 shows the final part made of SiC obtained in this example.

[0227] FIG. 6 is a photograph taken in optical microscopy that shows the microstructure of the final material constituting the part obtained.

[0228] FIG. 7 is a photograph taken in scanning electron microscopy (SEM) that shows the microstructure of the final material constituting the part obtained.

[0229] FIGS. 6 and 7 show: [0230] [1] SiC grains; [0231] [2] amorphous SiC from the polymer; [0232] [3] a porosity; [0233] [4] SiC deposited by CVI; [0234] [5] SiC deposited by CVD.

Example 2

Production of a Plate Made of MoSi.SUB.2.SiC.

[0235] In this example, a plate made of MoSi.sub.2SiC is manufactured, by the method according to the invention.

[0236] The procedure is the same as in Example 1, but with the following differences: [0237] a base powder of MoSi.sub.2, available from H.C. Starck under the name Amperit 920-054 (particle size 15-45 microns), instead of a SiC powder, is mixed with the plaster powder, in the mass proportions of 80% MoSi.sub.2 and of 20% plaster. [0238] a plate of 10 cm2 cm3 mm is obtained by mixing the preceding powder with a solution of 65% of polycarbosilane and 35% of toluene (% by mass), then casting in a mould. [0239] the part is subsequently placed in a CVI furnace with the following infiltration conditions: temperature 950 C., pressure 4 kPa, ratio of the [H.sub.2]/[CH.sub.3SiCl.sub.3] gas flow rates=4, duration 40 h.

[0240] The other steps, impregnation, pyrolysis, heat treatments and elimination of the plaster are carried out in the same conditions as in Example 1.

[0241] The part obtained consists, by mass, of 78% of MoSi.sub.2, of 17% of SiC obtained by CVI, and of 5% of SiC from the polymer.

[0242] The part has a density of 4.4 g/cm.sup.3.

REFERENCES

[0243] [1] UHT Ceramics: densification, properties and thermal stability, J. F. Justin, Journal Aerospace Lab, Issue 3, p 1-11, November 2011. [0244] [2] Ultrahigh temperature ceramic-based composites, Y. Kawaga, p 273-292, in Ceramic Matrix Composites, Wiley and Sons, 2015. [0245] [3] Sintering additives for SiC based on the reactivity: a review, K. Raju, Ceramics International 42, p 17947-17962, 2016. [0246] [4] Volumetric receivers in Solar Thermal Power Plants with Central Receiver System technology: A review, A. Avila Marin, Solar Energy, vol. 85, pp. 891-910, 2011. [0247] [5] Pressureless sintering of HfB.sub.2-SiC ceramics, D. W Ni, Journal of the European Ceramic Society 32 (2012) 3627-3635. [0248] [6] Additive free hot-pressed SiC ceramicsA material with exceptional mechanical properties, P. Sagjgalik, Journal of European Ceramic Society 36, 1333-1341, 2016. [0249] [7] Procd de fabrication de matriau composite matrice carbure, S. Jacques, FR-A1-3 004 712, of 19 Apr. 2013. [0250] [8] Polymer-Derived Ceramics: 40 years of research and innovation in Advanced Ceramics, P. Colombo, J. Am. Ceram. Soc., 93, [7], 1805-1837, 2010. [0251] [9] C/SiC and C/C-SiC composites, B. Heidenreich, p 147-216, in Ceramic Matrix Composites, Wiley and Sons, 2015. [0252] [10] Chemical vapor deposited silicon carbides articles, Lais Kevin D., patent, EP 1 970 358 A1 of 17 Sep. 2008. [0253] [11] Manufacturing SiC-fiber-reinforced SiC matrix composites by improved CVI/slurry/Infiltration/Polymer impregnation and pyrolysis, C. A Nannetti, J. Am. Ceram. Soc. 87 [7] 1205-1209, 2004. [0254] [12] JP-A-2003-238249. [0255] [13] US-A1-2003/162647.