SYSTEM AND METHOD FOR FOUR-DIMENSIONAL PRINTING OF CERAMIC ORIGAMI STRUCTURES

Abstract

A system and method of constructing a 4D-printed ceramic object includes extruding inks including particles and polymeric ceramic precursors through a nozzle to deposit the inks on a heating plate, whereby a 3D-printed elastomeric object is formed on the heating plate, folding the 3D-printed elastomeric object into a complex structure to form a 4D-printed pre-strained elastomeric object, and converting the 4D-printed elastomeric object into the 4D-printed ceramic object.

Claims

1. A method of constructing a 4D-printed ceramic object, the method comprising: extruding inks including particles and polymeric ceramic precursors through a nozzle to deposit the inks on a heating plate, whereby a 3D-printed elastomeric object is formed on the heating plate, folding the 3D-printed elastomeric object into a complex structure to form a 4D-printed pre-strained elastomeric object, and converting the 4D-printed elastomeric object into the 4D-printed ceramic object.

2. The method of claim 1, wherein the particles are zirconium dioxide nanoparticles.

3. The method of claim 1, wherein the polymeric ceramic precursors are poly(dimethylsiloxane).

4. The method of claim 1, wherein the temperature of the heating plate is in the range of from about 30 C. to about 400 C.

5. The method of claim 1, wherein the folding of elastomeric object is achieved by metal wires.

6. The method of claim 1, wherein the polymer-to-ceramic transformation occurs via pyrolysis in a vacuum or under an inert atmosphere.

7. The method of claim 1, wherein the 4D-printed ceramic object has a Gaussian curvature.

8. The method of claim 1, wherein the 4D-printed ceramic object has a dimension of 100 m or more.

9. The method of claim 1, wherein the inks are formed from a homogenous distribution of the particles in the polymeric ceramic precursors and wherein the weight percentage of the particles in the inks is in the range of from about 1% to about 90% and the weight percentage of the polymeric ceramic precursors in the inks is in the range of from about 10% to about 99%.

10. The method of claim 6, wherein the heating temperature of polymer-to-ceramic transformation is 400 C. to 2000 C.

11. The method of claim 6, wherein the polymer structures undergo limited and uniform shrinkage during the polymer-to-ceramic transformation and wherein the 4D-printed ceramic object has substantially the same shape as the 4D-printed elastomeric object.

12. The method of claim 1, wherein the particles are characterized by an average diameter of about 100 m or less.

13. The method of claim 1, wherein the particles are uniformly distributed powders.

14. The method of claim 1, wherein the elastomer object is locally or partially heated in order to achieve the ceramic-organic structure.

15. The method of claim 1, wherein the folding of elastomeric object is achieved by use of at least one of metal wires, prestretch devices, metal plates, polymer wires, polymer plates, carbon wires, carbon plates, silicon wires, silicon plates, shape memory alloys and shape memory polymers.

16. The method of claim 1, wherein the polymeric ceramic precursors include at least one of polysiloxanes, polysilsesquioxanes, polycarbosiloxanes, polycarbosilanes, polysilylcarbodiimides, polysilsesquicarbodiimides, polysilazanes and polysilsesquiazanes.

17. The method of claim 1, wherein the particles include at least one of zirconium dioxide particles, calcium oxide particles, aluminium oxide particles, titanium dioxide particles, indium oxide particles, zinc oxide particles, silicon dioxide particles, aluminium nitride particles, calcium silicate particles, silicon carbide particles, polymeric particles, metallic particles, carbon black particles, graphene particles, graphite particles, diamond particles and refractory materials.

18. The method of claim 15, wherein during the polymer-to-ceramic transformation the pre-strain is programmed by robotics or shape memory alloy or thermal expansion or relaxation of residual stress or laser cutting of ligaments or combinations thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Notwithstanding any other forms which may fall within the scope of the present invention, a preferred embodiment will now be described, by way of example only, with reference to the accompanying drawings in which:

[0029] FIG. 1 illustrates the DIW-origami-SCOP method in accordance with an embodiment of the invention, wherein part a illustrates 3D-printed elastomeric lattices for origami; part b illustrates a schematic of the DIW method; part c illustrates the step of metal wire-assisted origami converting 3D-printed elastomer into pre-strained precursors; part d illustrates the step of pyrolysis converting pre-strained precursors into 4D-printed ceramics; part e illustrates the first PDCs obtained after etching of the metal wire; and part f illustrates the step of oxidation converting the first PDCs into second PDCs:

[0030] FIG. 2 shows an example of a 3D-printed large-scale elastomeric honeycomb:

[0031] FIG. 3 shows an example of a 3D-printed microlattice (part (a)) and honeycomb (part (b)) of PDMS NCs, first PDCs and second PDCs (left to right);

[0032] FIG. 4 shows an example of hierarchical nanostructures of second PDCs illustrated by digital photo (part a; scale bar, 5 mm), SEM image of the microlattice (part b; scale bar, 200 m), SEM image of the cross-section (part c; scale bar, 100 nm), and pore size distribution (part d), with part e showing schematic representation of the relevant dimensions of such hierarchical ceramic nanostructures;

[0033] FIG. 5 shows an example of the porosity of PDCs (part a), N.sub.2 adsorption/desorption isotherm of first and second PDCs (part b), wherein the inset shown in part b provides cumulative pore volume and pore size distribution of first and second PDCs;

[0034] FIG. 6 shows the flexibility and stretchability of printed elastomer presented by bending, twisting and stretching:

[0035] FIG. 7 shows representative ceramic origami objects mimicking a butterfly, the Sydney Opera House, a rose and a dress:

[0036] FIG. 8 shows a large-scale 4D-printed ceramic;

[0037] FIG. 9 shows complex 4D-printed ceramics with mixed Gaussian curvature (K) generated by DIW-origami-SCOP method, wherein parts a and d shows positive K (spherical caps) and zero K (cylinders) in 4D-printed ceramics, part b shows, Positive K (the outer region of the torus) and negative K (the inner region of the torus) in 4D-printed ceramics, and part c shows Zero K (cones and cylinders) in 4D-printed ceramics:

[0038] FIG. 10 shows compressive strength-density Ashby Chart. SiOC matrix NCs architectures with high specific compressive strength in this work (red stars), are compared with other ceramic structures as reported in the reference and commercial available SiC foam and AlSiO foam;

[0039] FIG. 11 shows strength-scalability synergy. Architectured PDCs with simultaneous high strength and large area; and

[0040] FIG. 12A, FIG. 12B, FIG. 12C and FIG. 12D is an illustration of an example geometric representation of the associated entries in Table 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0041] In the ensuing description, certain terms, once introduced, will be abbreviated for the sake of brevity and to improve readability. It will be understood that the use of such abbreviations should not be construed as being limiting or otherwise placing a gloss on the meanings of such terms beyond the meanings that would be placed on the terms when construed by a skilled addressee.

[0042] The present invention, in at least one embodiment, provides a method of constructing a 4D-printed ceramic object, the method comprising extruding inks comprising particles; and polymeric ceramic precursors, through a nozzle to deposit the inks on a heating plate, whereby a 3D-printed elastomeric object is formed on the heating plate, folding 3D-printed elastomeric object into complex origami or kirigami structures, whereby a 4D-printed pre-strained elastomeric object is formed; and converting the 4D-printed elastomeric object into the 4D-printed ceramic object, whereby a 4D-printed ceramic object is formed.

[0043] In more detail, the silicone rubber NanoComposites (NCs) utilised are ZrO.sub.2 nanoparticles (NPs) reinforced with Poly(DiMethylSiloxane) (PDMS).

[0044] PDMS is a dominant elastomer in silicone systems and is useful as a ceramic precursor, while providing inherent flexibility to construct a material that is suitable for origami folding. Furthermore, the stretchability of PDMS allows for the creation of delicate origami structures with mixed Gaussian curvatures. The structure can have positive Gaussian curvatures, negative Gaussian curvatures, zero Gaussian curvature or combinations thereof.

[0045] In the example given with reference to the Figures, crystalline ZrO.sub.2 NPs with a primary average size of 20-50 nm in diameter were incorporated into a PDMS matrix, forming a jammed network within the polymer matrix while serving as barriers to mass and heat transfer in the polymer matrix, to thereby eliminate shrinkage upon ceramization.

[0046] The polymer-to-ceramic transformation is preferably achieved by pyrolysis in inert atmosphere, oxidation in oxidative atmosphere or a combination of the techniques.

[0047] It will be understood that the particles (NPs) may also be calcium oxide particles, aluminium oxide particles, titanium dioxide particles, indium oxide particles, zinc oxide particles, silicon dioxide particles, aluminium nitride particles, calcium silicate particles, silicon carbide particles, polymeric particles, metallic particles, carbon black particles, graphene particles, graphite particles, diamond particles, other refractory materials or any combination of the particles listed above.

[0048] The particles, in the embodiment, are characterized by an average diameter of about 100 m or less and may be uniformly or non-uniformly distributed powders or fibers or tubes or any other regular shapes or any other combination of the above.

[0049] In the embodiment described herein, a known cost efficient 4D printing method is used. The method combines Direct Ink Writing (DIW) with synchronous thermal crosslinking of extruded pre-polymer inks, as shown in FIG. 1b. The inks are formed, in the embodiment, from a homogenous distribution of the particles in the polymeric ceramic precursors. In one preferred example, the weight percentage of the particles in the inks is in the range of from about 1% to about 90% and the weight percentage of the polymeric ceramic precursors in the inks is in the range of from about 10% to about 99%.

[0050] The heating plate is preferably in the range from about 30 C. to about 400 C.

[0051] 3D-printed elastomer (see FIG. 1a), together with metal wire are prepared. While wires are used in the embodiment described herein, it will be understood that other pre-stretched devices may also be utilised. This can include metal plates, polymer wires, polymer plates, carbon wires, carbon plates, silicon wires, silicon plates, shape memory alloys, shape memory polymers or any combination of the above.

[0052] Taking the simplest folding as an example, the elastomeric ceramic precursors were buckled as a function of the pre-strain (see FIG. 1c).

[0053] It will be understood that the polymeric ceramic precursors may be polysiloxanes, polysilsesquioxanes, polycarbosiloxanes, polycarbosilanes, polysilylcarbodiimides, polysilsesquicarbodiimides, polysilazanes, polysilsesquiazanes or any combination of the above.

[0054] In addition, a method was developed to produce PDCs that have been termed Synthetic Ceramics by Oxidation after Pyrolysis (SCOP). This method converted PDMS NCs into SiOC matrix NCs (first PDCs) via pyrolysis in argon or under vacuum (see FIG. 1d), followed by oxidation in air, yielding second PDCs (see FIG. 10f).

[0055] The metal wire was etched in HNO.sub.3 after the polymer-to-ceramic transformation (see FIG. 1e), and the chemical resistance of ceramics to corrosion guarantees structural stability during the process.

[0056] The first PDCs, as precursors of second PDCs, assisted in the formation of a dense SiOC framework. The dense framework allowed for the production of a 4D-printed ceramic origami with complex curvatures as shown in FIG. 1.

[0057] Representative periodic structures, including lattices and honeycombs, are fabricated using the DIW-SCOP method described above. The scalability of the DIW method is demonstrated by the production of a large-area elastomeric honeycomb (FIG. 2). As can be seen from FIG. 3, isotropic shrinkage in the transformations causes good shape retention. Oxidation of the 1st PDCs at 1,000 C. is accompanied by a 2.4% mass loss and a 2.5% linear shrinkage, while 35% mass loss and 20% linear shrinkage occurring for pyrolysis of the PDMS NCs at 1,000 C.

[0058] Use of a Scanning Electron Microscopy (SEM) technique reveals that the spatial resolution of the printed microstructures (FIG. 4a) for the samples are 200 m (as seen in FIG. 4b), which is determined by a combination of the nozzle diameter and shrinkage during transformation.

[0059] In the cross section of resultant ceramic lattices, NPs with the diameter of 20-50 nm are observed (see FIG. 4c). The degradation of the PDMS matrix with well-distributed NPs yields porous ceramics with Brunauer-Emmett-Teller (BET) surface areas of 184 m.sup.2g.sup.1 and 138 m.sup.2g.sup.1 for the first and second PDCs, respectively (see FIG. 5).

[0060] The pore size distribution of PDCs indicated suprananopores with a diameter of 2-10 nm (see FIG. 4d and FIG. 5). The suprananoporous ceramics, integrated with printed microstructures, can provide high flux and desired pore accessibility, for example, in ceramic catalyst support.

[0061] The programmable structural hierarchy of the abovementioned ceramic nanostructures spans three orders of magnitude, from 200 m to 10 cm (see FIG. 4e).

[0062] The flexibility and stretchability of printed elastomer, demonstrated by some fundamental loading modes like bending, twisting and stretching, suggested possibilities for origami assembly (see FIG. 6).

[0063] Representative ceramic origami structures with complex curvatures, mimicking a butterfly, the Sydney Opera House, a rose and a dress, were built from 3D-printed cuboid or cubic pre-strained precursors (FIG. 7). The 3D-printed elastomeric lattices undergo morphological transformation and are deterministically constrained by the metal wire, yielding 4D-printed ceramics.

[0064] The printed periodic local patterns in elastomeric lattices improve the foldability of global structures and guaranteed the programmability in locating constraints.

[0065] The scalability of this method is demonstrated by the curved ceramic honeycombs with a maximum dimension of nearly ten centimeters (FIG. 8). The equilibrium morphologies are determined by balancing bending and stretching energies, and such competition results in a thickness-dependent equilibrium state.

[0066] Based on Gauss's Theorema Egregium, the stretchability of the elastomer offers opportunities to building sophisticated structures with mixed Gaussian curvature by changing distances between the points on the surface. Typical zero Gaussian curvature, such as cylinders and cones, and positive Gaussian curvature like spherical caps were generated in resultant 4D-printed ceramics, as well as negative Gaussian curvature exhibited in the saddle-shaped inner region of the torus (see FIG. 9).

[0067] While prior art solutions have had difficulty printing complex structures directly with overhanging unsupported features and mixed Gaussian curvatures, the DIW-origami-SCOP method of the embodiment overcomes such limitations.

[0068] Moreover, the use of kirigami assembly techniques can be integrated into the DIW-SCOP method as another powerful and customizable approach for 4D-printed ceramics. To characterize the mechanical robustness of these ceramic architectures, compression tests were performed on printed ceramic lattices and honeycombs, for both the first and second PDCs. The results are summarized in FIG. 10, FIG. 11, and in the compression test samples of Table 1 (below).

TABLE-US-00001 Dimensions Mass Dimensions Mass Com- Atmosphere of the of the of the of the pressive in d a b precursor* precursor sample sample Density strength Material pyrolysis Architecture Geometry (m) (mm) (mm) (mm) (g) (mm) (g) (g cm.sup.3) (MPa) 1.sup.st Vacuum Lattice See 210 0.64 0.64 10.40 10.38 0.162 8.40 8.40 0.108 1.177 205.8 PDCs FIG. 12A 1.59 1.30 1.sup.st Vacuum Lattice 210 0.64 0.64 10.32 10.32 0.151 8.33 8.33 0.099 1.141 160.4 PDCs 1.52 1.25 1.sup.st Vacuum Lattice 210 0.64 0.64 10.50 10.50 0.136 8.44 8.42 0.089 1.035 150.2 PDCs 1.54 1.21 1.sup.st Argon Lattice 210 0.64 0.64 10.72 10.61 0.173 8.62 8.52 0.112 1.164 207.0 PDCs 1.60 1.31 1.sup.st Argon Lattice 210 0.64 0.64 10.72 10.59 0.155 8.57 8.49 0.100 1.135 211.2 PDCs 1.51 1.21 1.sup.st Argon Lattice 210 0.64 0.64 10.70 10.58 0.148 8.62 8.42 0.094 1.079 174.0 PDCs 1.46 1.20 1.sup.st Argon Honeycomb See 210 2.25 1.30 11.02 10.25 0.086 8.96 8.30 0.057 0.494 34.2 PDCs FIG. 12B 1.93 1.55 1.sup.st Argon Honeycomb 210 2.25 1.30 11.06 10.21 0.088 8.85 8.28 0.057 0.572 53.9 PDCs 1.66 1.36 1.sup.st Argon Honeycomb 210 2.25 1.30 11.20 10.49 0.080 8.98 8.54 0.052 0.542 58.8 PDCs 1.58 1.25 1.sup.st Argon Honeycomb 210 2.25 1.30 10.95 10.29 0.135 8.90 8.39 0.087 0.637 41.6 PDCs 2.30 1.83 1.sup.st Argon Honeycomb 210 2.25 1.30 11.13 10.02 0.116 8.92 8.10 0.075 0.618 46.8 PDCs 2.12 1.68 1.sup.st Argon Honeycomb 210 2.25 1.30 10.86 10.07 0.145 8.74 8.18 0.095 0.688 42.9 PDCs 2.38 1.93 2.sup.nd Vacuum Lattice See 205 0.63 0.63 8.25 8.25 0.095 8.01 8.01 0.092 1.185 172.2 PDCs FIG. 12C 1.26 1.21 2.sup.nd Vacuum Lattice 205 0.63 0.63 8.40 8.34 0.093 8.11 8.24 0.090 1.141 150.7 PDCs 1.23 1.18 2.sup.nd Vacuum Lattice 205 0.63 0.63 8.38 8.42 0.097 8.20 8.18 0.095 1.164 175.2 PDCs 1.27 1.22 2.sup.nd Argon Lattice 205 0.63 0.63 8.64 8.51 0.099 8.43 8.31 0.098 1.137 169.3 PDCs 1.26 1.23 2.sup.nd Argon Lattice 205 0.63 0.63 8.59 8.51 0.101 8.40 8.30 0.100 1.176 182.9 PDCs 1.24 1.22 2.sup.nd Argon Lattice 205 0.63 0.63 8.57 8.53 0.091 8.40 8.34 0.090 1.117 169.2 PDCs 1.16 1.15 2.sup.nd Argon Honeycomb See 205 2.20 1.27 8.89 8.24 0.056 8.71 8.15 0.054 0.609 74.3 PDCs FIG. 12D 1.29 1.25 2.sup.nd Argon Honeycomb 205 2.20 1.27 9.05 8.53 0.053 8.90 8.31 0.051 0.518 57.7 PDCs 1.35 1.33 2.sup.nd Argon Honeycomb 205 2.20 1.27 9.02 8.52 0.060 8.60 8.30 0.057 0.587 57.3 PDCs 1.34 1.33 2.sup.nd Argon Honeycomb 205 2.20 1.27 8.84 8.14 0.078 8.61 7.92 0.076 0.671 55.9 PDCs 1.71 1.66 2.sup.nd Argon Honeycomb 205 2.20 1.27 8.84 8.36 0.095 8.56 8.12 0.094 0.791 75.1 PDCs 1.76 1.71 2.sup.nd Argon Honeycomb 205 2.20 1.27 8.88 8.31 0.093 8.60 8.05 0.092 0.764 70.7 PDCs 1.79 1.74 *Precursor: PDMS NCs for 1.sup.st PDCs; 1.sup.st PDCs for 2.sup.nd PDCs

[0069] The lattice exhibits a higher strength-to-density ratio than the honey comb, and a compressive strength of 211 MPa was achieved on first PDCs of the lattice structure at 1.1 gcm.sup.3.

ADVANTAGES AND INDUSTRIAL APPLICABILITY

[0070] The embodiments and broader invention described herein provide a number of advantages and have broad industrial applicability.

[0071] Firstly, the techniques and materials utilised and developed as part of the embodiments described herein allow for the creation of objects with a high geometrical complexity, including mixed Gaussian curvature.

[0072] Secondly, the objects produced have a high mechanical robustness, approximately 10 times higher than conventional SiOC foam in specific compressive strength tests.

[0073] Thirdly, there is a strength-scalability synergy demonstrated, meaning that the techniques and materials described herein have great potential for industrial scale production.

[0074] Fourthly, the techniques and materials utilised and developed as part of the embodiments are cost effective and can be printed in a cost efficient manner.

[0075] Fifthly, all the materials and techniques used in the embodiments are based on commercially available and open-end feedstock systems, further showing that the embodiments described herein have commercial potential and industrial applicability.

[0076] Lastly, in a more general sense, the abovementioned advantages provide the possibility that the materials and techniques of the embodiments can be utilized in many structural applications including autonomous morphing ceramic composites, aerospace propulsion components, and high-temperature microelectromechanical systems.

[0077] In more detail, and by way of example, the suprananoporous ceramics, integrated with printed microstructures, can provide high flux and desired pore accessibility in, for example, ceramic catalyst support.

[0078] In addition, the added use of programmable local heating on 4D-printed elastomers provides a way to fabricate globally tough ceramic-organic architectures. Such pre-strained elastomer-derived ceramic origami based on additive manufacturing technique find use in aerospace propulsion, shape memory ceramics and bio-inspired tough ceramic-organic hybrid materials.