Method of making flexible ceramic fibers and polymer composite
AssigneeEurekite Holding B.V.
InventorsGerard Cadafalch Gazquez, Roger Brunet Espinosa, Johan Evert Ten Elshof
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Abstract
The present application discloses and claims a method to make a flexible ceramic fibers (Flexiramics™) and polymer composites. The resulting composite has an improved mechanical strength (tensile) when compared with the Flexiramics™ respective the nanofibers alone. Additionally a composite has better properties than the polymer alone such as lower fire retardancy, higher thermal conductivity and lower thermal expansion. Several different polymers can be used, both thermosets and thermoplastics. Flexiramics™ has unique physical characteristic and the composite materials can be used for numerous industrial and laboratory applications.
Claims10
A process for making a flexible composite material comprising flexible ceramic nanofibers and a polymer, the process of making flexible ceramic nanofibers comprising the steps of:
- a) preparing a ceramic fiber precursor solution comprising
- (i) a dissolved metal precursor for ceramic selected from the group consisting of metallic ions and metal containing polymer and selected from the group consisting of Si4+, Zr4+, Ti4+, Y3+, Al3+, Zn2+, Mg2+, Pb4+, Ni2+, Sr2+, Ca2+, La3+;
- (ii) a polymer to increase the precursor solution viscosity, with the solid content of the precursor solution being above 5% by weight in order to obtain the required deposition, and
- (iii) solvent capable of providing the precursor solution a sufficiently high evaporation rate;
- b) allowing the dissolved metal precursors for ceramic to form a final ceramic metal oxide;
- c) maintaining the precursor solution viscosity between 0.01 and 1000 Pascal-second at a shear rate of 0.01 to 1 s−1 in order to spin usable fibers;
- d) blow spinning the precursor solution while setting the spinning parameters so that the spinning results in polymeric fibers and adapting the spinning parameters to the precursor solution;
- e) annealing the polymeric fibers comprising the metallic precursors comprising the metal precursors for ceramic obtained from the spinning process until all organic content is burned out and the metallic ion oxidizes to form a ceramic;
- f) tuning and calibrating annealing parameters comprising heating and cooling rates, annealing temperature and dwell time consistent with a trapezium shaped thermal profile so a crystallinity comprising a crystal size of 1 to 100 nm and a smoothness of 0.05 to 5 nm of root mean square roughness of the resulting 20 to 10000 nm thick fibers is obtained, the annealing parameters being distinct and specific with respect to material composition;
- g) setting the annealing temperature above a crystallization point of the ceramic fiber to form ceramic material;
- and
- h) rendering the composite dense with no porosity by the steps of either
- a′) casting non-diluted or little diluted polymeric solution on the ceramic nanofibers on flat and rigid surfaces with thickness between 0.1 to 5.0 millimeters;
- b′) depositing the ceramic nanofiber on top of the cast solution thus allowing the solution to permeate through the entire sample via capillary forces;
- and
- c′) thermally curing the resulting solution permeated sample by placing the sample into an oven at temperatures between 20° C. and 300° C. over a pre-determined curing time, and the cured sample comprising a polymer layer on one or on both sides of the composite with a thickness ranging from 1 μm to 5 mm;
- or
- a″) melting the polymer on top or bottom of the ceramic nanofibers;
- b″) applying pressure and/or temperature for better infiltration of the polymer in the ceramic nanofiber matrix, and
- c″) decreasing the temperature to solidify the polymer.
Dependencies are inferred from the claim text.