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US 12,577,171 B2Granted
Process for obtaining composite, ultra-refractory, fibre-reinforced ceramic materials
AssigneeConsiglio Nazionale Delle Ricerche
InventorsLuca Zoli, Diletta Sciti, Laura Silvestroni, Antonio Vinci
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Abstract
The present invention relates to a process for preparing a composite, ultra-refractory, fibre-reinforced ceramic material obtained through the infiltration of carbon and/or silicon carbide fibres with a ceramic suspension comprising yttrium, lanthanum and/or scandium compounds, and the subsequent densification of the composite. The fibre-reinforced UHTC compounds obtained by the process can be used for making items intended for use in extreme temperature and pressure conditions.
Claims17
A process for preparing a composite, ultra-refractory, fibre-reinforced ceramic material (UHTC) comprising:
- (i) infiltrating a plurality of fibres selected from carbon fibres, silicon carbide fibres and combinations thereof, wherein said plurality of fibres are covered by a protective carbon coating, with a ceramic suspension, thereby obtaining an infiltrated composite material, and drying the infiltrated composite material, wherein the ceramic suspension comprises:
- (A) a mixture of solid ceramic phases comprising:
- (a) an amount greater than or equal to 55 vol. % of an ultra-refractory ceramic component selected from the group consisting of ZrB2, HfB2, TaB2, TiB2, NbB2, ZrC, HfC, TiC, NbC, TaC and mixtures thereof;
- (b) 0-30 vol. % of SiC;
- (c) 0.1-15 vol. % of a scandium compound;
- and
- (B) a dispersant selected from the group consisting of water, organic solvents, liquid organic precursors of SiC, liquid organic precursors of carbon and mixtures thereof;
- (ii) consolidating the dried composite material at a temperature comprised in the range 1400°-2000° C.,
- wherein the ultra-refractory, fibre-reinforced ceramic material UHTC so obtained is characterized by
- a density less than or equal to 4 g/cm3, and/or
- a fracture toughness greater than or equal to 4 MPa·m1/2.
8 more elements
A process for obtaining UHTC composites reinforced with short fibres, said process comprising:
- (i.a1) dispersing a plurality of fibres having a length of about 25-6000 μm, wherein said plurality of fibres are covered by a protective carbon coating, in a ceramic suspension and grinding the dispersion, obtaining an infiltrated composite material;
- and
- (i.b1) shaping and drying the infiltrated composite material with a shaping method selected from the group consisting of spray application, slip casting, tape casting and pressing, wherein the ceramic suspension comprises
- (A) a mixture of solid ceramic phases comprising:
- (a) an amount greater than or equal to 55 vol. % of an ultra-refractory ceramic component selected from the group consisting of ZrB2, HfB2, TaB2, TiB2, NbB2, ZrC, HfC, TiC, NbC, TaC and mixtures thereof;
- (b) 0-30 vol. % of SiC;
- (c) 0.1-15 vol. % of a scandium compound;
- and
- (B) a dispersant selected from the group consisting of water, organic solvents, liquid organic precursors of SiC, liquid organic precursors of carbon and mixtures thereof;
- (ii) consolidating the dried composite material at a temperature comprised in the range 1400°-2000° C.,
- wherein said UHTC composites reinforced with short fibres are characterized by flexural strength at 25°±2° C. greater than 150 MPa;
- flexural strength at 1500° C. in a reducing atmosphere greater than 200 MPa;
- and
- thermal shock resistance greater than 1000° C.
11 more elements
A process for obtaining UHTC composites reinforced with long fibres, said process comprising:
- (i.a2) infiltrating at least one preform comprising a plurality of fibres having a length that is greater than 6000 μm, wherein said plurality of fibres are covered by a protective carbon coating, with a ceramic suspension with a method selected from hand lay-up, dip coating and filament winding, obtaining an infiltrated composite material;
- and
- (i.b2) drying the infiltrated composite material, wherein the ceramic suspension comprises (A) a mixture of solid ceramic phases comprising:
- (a) an amount greater than or equal to 55 vol. % of an ultra-refractory ceramic component selected from the group consisting of ZrB2, HfB2, TaB2, TiB2, NbB2, ZrC, HfC, TiC, NbC, TaC and mixtures thereof;
- (b) 0-30 vol. % of SiC;
- (c) 0.1-15 vol. % of a scandium compound;
- and
- (B) a dispersant selected from the group consisting of water, organic solvents, liquid organic precursors of SiC, liquid organic precursors of carbon and mixtures thereof;
- (ii) consolidating the dried composite material at a temperature comprised in the range 1400°-2000° C.,
- wherein said UHTC composites reinforced with long fibres are characterized by flexural strength at 25°±2° C. greater than 400 MPa for composite with 0°/0° orientations of the preforms;
- flexural strength at 1500° C. in reducing atmosphere greater than 500 MPa for composites with 0°/0° orientations of the preforms;
- and
- thermal shock resistance greater than 1000° C. for composite with 0°/0° orientations or 0°/90° orientations of the preforms.
10 more elements
Dependencies are inferred from the claim text.