KR102420253B1 - Glass components with custom-tailored composition profiles and methods for preparing same - Google Patents

Abstract

According to one embodiment, a method comprises forming a structure by printing an ink comprising a glass-forming material and heat-treating the formed structure to convert the glass-forming material to glass.

Description

GLASS COMPONENTS WITH CUSTOM-TAILORED COMPOSITION PROFILES AND METHODS FOR PREPARING SAME

The U.S. Government has issued the present invention under contract number DE-AC52-07NA27344 between the United States Department of Energy and Lawrence Livermore National Security, LLC for the operation of Lawrence Livermore National Laboratory. have the right to

FIELD OF THE INVENTION The present invention relates to glass members, and more particularly to optical and non-optical glass members having user-customizable composition profiles and methods of making the same.

Typically, a gradient in material composition is introduced axially by either (1) fusing together multiple layers of uniform composition, or (2) adding species (typically small, rapidly diffusing ions) to rod-shaped silica sols at elevated temperatures. It is introduced radially by diffusing into or from the gel or solid. Unfortunately, purely diffusion-based gradients are limited to symmetrical parabolic profiles, with a maximum achievable diameter of ∼20 mm (for radial gradient refractive index lenses), with most commercial forms having a diameter of 2 less than mm. It turns out that introducing larger and slower diffusing species is a challenge.

Some attempts have been made to form single-composition glasses through additive manufacturing. Single composition silica glass has been produced through additive prototyping using selective laser melting (SLM), which is the melting and fusing of silica particles in a bed of silica powder. In addition, single composition glass has been produced via the additive manufacturing method (G3DP), in which silica is melted in a high-temperature vessel similar to a kiln and a molten glass ribbon is laminated through a nozzle. In this way, selectively molten regions are obtained that are susceptible to thermally induced stresses upon cooling or filaments, so that, for example, an unwanted refractive index gradient is formed across the thickness of the part, whereby the part does not achieve optical quality. . Moreover, selectively molten regions can also result in resistance to coalescence of the segments by leaving trapped pores between the segments. In addition, these methods are not in favor of the tightly controlled introduction of various compositions. It would be desirable to be able to print and completely form structures without high temperatures.

Various embodiments described herein use direct ink writing (DIW) layered molding to introduce a compositional gradient into an amorphous low density form (LDF). After complete formation, the LDF is heat treated to become transparent as a whole structure, thus reducing edge effects.

Current methods of forming gradient composition glasses have also been found to be challenging. In a slurry-based 3D printing (S-3DP) system, after the LDF is built up from the slurry and dried, the dopant is added. This process requires structural integrity within the LDF. In addition, introduction of a dopant in a low-viscosity droplet on a dried object causes the species of interest to diffuse radially and axially, potentially filling the pores of the underlying dried structure through capillary forces, which Control over the composition gradient may be poor. Compositional gradients can also be limited to materials (eg small molecules, ions) that can be readily incorporated into the LDF by diffusion. Accordingly, it would be desirable to develop a process for forming a glass of a gradient composition wherein the dopant is a component of the mixture during formation of the LDF and prior to drying of the LDF.

The various embodiments described herein allow (1) the formation of optical or non-optical glasses with custom composition profiles not achievable by conventional glass processing techniques, and (2) species that cannot be readily introduced by diffusion methods. and (3) the formation of glass optical bodies with tailored patterned material properties that are much greater than those achievable by diffusion methods.

Some embodiments described herein, with or without dopants, introduce a gradient via DIW layered prototyping and use continuous-line mixing of glass-forming species to achieve the desired compositional change. The LDF is fully formed before drying. The dopant itself may be ions, molecules and/or particles and may be premixed with the glass-forming species into a highly viscous suspension, thereby limiting its diffusion in the LDF at low temperatures.

According to one embodiment, a method comprises forming a structure by printing an ink comprising a glass-forming material and heat-treating the formed structure to convert the glass-forming material to glass.

According to another embodiment, the product comprises a monolithic glass structure having the physical characteristics of formation by three-dimensional printing of an ink comprising a glass-forming material. Other aspects and advantages of the present invention will become apparent from the following detailed description, which, taken in conjunction with the drawings, illustrates the principles of the invention.

1 is a flow diagram of a method for making a glass member having a user-customizable composition profile, according to one embodiment.
2A is a schematic diagram of a method for making a single composition glass member, according to one embodiment.
2B is a schematic diagram of a method for making a multi-component glass member, according to one embodiment.
3A is an image of an extrudate of glass-forming ink on a substrate, according to one embodiment.
3B is an image of a printed low-density object, according to one embodiment.
3C is an image of a glass body after heat treatment of a printed low-density body, according to one embodiment.
4A is a schematic diagram of a low-density object comprising a material property gradient of the low-density object along an axial direction, according to one embodiment.
4B is a schematic diagram of a low-density object including a material property gradient of the low-density object along a radial direction, according to one embodiment.
5A is an image of a low-density shaped body having a gradient in the axial direction, after printing of multiple components, according to one embodiment.
5B is an image of a glass body having a gradient in the axial direction after heat treatment of a printed low density body according to one embodiment.
5C is an image of a low-density shaped body having a gradient in a radial direction, after printing of multiple components, according to one embodiment.
4B is an image of a glass object having a gradient in a radial direction after heat treatment of a printed low-density object according to one embodiment.
6A-6C are images of printed parts formed with a silica composition, according to one embodiment.
6D-6E are images of printed parts formed to have a silica-titania composition, according to one embodiment.
7A is a plot of the refractive index profile versus titania concentration of a glass formed in accordance with one embodiment.
7B is an image of resultant glass structures formed with various titania concentrations, according to one embodiment.
8 is a plot of a heat treatment profile of formation of a consolidated structure according to one embodiment. Images of each step are included as insets on the profile plot.
9A is an image of a gradient refractive index silica-titania glass lens made by direct ink writing, according to one embodiment.
9B is a surface-corrected interferogram of the glass lens of FIG. 9A.
9C is an image at 300-μm focus from the lens of FIG. 9A.
10A is an image of a composite glass composed of a gold-doped silica glass core, according to one embodiment.
10B is a plot of absorbance as a function of wavelength of light of the composite glass of FIG. 10A.
10C is a plot of absorbance at 525 nm of the composite glass of FIG. 10A versus positions along the glass surface.

The following description is made for the purpose of illustrating the general principles of the invention and is not intended to limit the inventive concept as claimed herein. Additionally, certain traits described herein may be used in each of the various possible combinations and permutations of the other described traits.

Unless specifically defined otherwise herein, all terms have their broadest possible meaning, including not only the meaning implied from the specification, but also the meaning as understood by one of ordinary skill in the art and/or as defined in dictionaries, articles, etc. should have an interpretation.

It should also be noted that, as used in the specification and appended claims, the singular forms "a, an" and "the" include plural referents unless otherwise specified.

The following description discloses several preferred embodiments of the manufacture of optical and non-optical glass members having user-customizable composition profiles, and/or related systems and methods.

In one general embodiment, a method comprises forming a structure by printing an ink comprising a glass-forming material and heat-treating the formed structure to convert the glass-forming material to glass.

In another general embodiment, the product comprises a monolithic glass structure having the physical characteristics of formation by three-dimensional printing of an ink comprising a glass-forming material.

A list of acronyms used in the description is provided below.

3D three-dimensional

DIW direct ink recording

FDM fusion stacking modeling

IR Infrared

G3DP Glass 3D Printing

GRIN gradient index glass

LDF low density compact

Si silicon

S-3DP slurry-based three-dimensional printing

SLM Selective Laser Melting

Ti titanium

UV UV rays

Various embodiments described herein provide methods for fabricating active or passive optical or non-optical glass members and/or glass sensors with custom material composition profiles in 1-, 2-, or 3-dimensional. The various embodiments described herein enable three-dimensional (3D) printing of various inorganic glasses with or without compositional changes. Depending on the glass composition and processing conditions, the glass may appear transparent or opaque to the human eye. However, the term “optical glass” not only refers to glasses useful in the visible portion of the spectrum, but can also be extended to UV, visible, near-IR, mid-IR, and far-IR.

1 shows a method 100 for making an optical glass member having a user-customizable composition profile according to one embodiment. Optionally, the method 100 may be implemented with an apparatus such as shown in other figures described herein. However, of course, this method 100 and others presented herein may be used to form structures for a wide variety of devices and/or purposes that may or may not be relevant to the exemplary embodiments listed herein. Additionally, the methods presented herein can be performed in any desired environment. Moreover, more or less work than shown in FIG. 1 may be included in method 100 , according to various embodiments. It should also be noted that any of the features mentioned above may be used in any of the embodiments described according to various methods.

In one embodiment as shown in FIG. 1 , method 100 begins with operation 102 comprising forming a structure by printing ink. According to various embodiments, the printing of the inks may include one of the following additive prototyping techniques that may have ink miscibility: direct ink writing (DIW), stereolithography in 3D systems, projection microstereolithography (projection microstereolithography), fusion deposition modeling, electrophoretic deposition, PolyJet processing, direct deposition, inkjet printing, inkjet powder bed printing, aerosol jet printing, etc. Combining these methods is also contemplated.

According to various embodiments, method 100 can be used to form filaments, films, and/or 3D monolithic or spanning free-forms.

According to one embodiment, the ink comprises a glass-forming material. According to another embodiment, the glass-forming material comprises a prepared particle dispersion, wherein the particles range in size from nanometers to micrometers. In some approaches, the particles may be monodisperse. In another approach, the particles may be polydisperse. In another approach, the particles may be agglomerated.

In another embodiment, the glass-forming material is, for example, fumed silica, colloidal silica, LUDOX colloidal silica dispersion, titania particles, zirconia particles, alumina particles, metal chalcogenide particles (eg, For example, CdS, CdSe, ZnS, PbS), etc., but is not limited thereto, may be inorganic particles of a single composition. In other embodiments, the glass-forming material may be inorganic-containing particles of a single composition.

In one embodiment, the glass-forming material can be a plurality of mixed composition particles, for example, but not limited to, bicomponent silica-titania particles, silica-germanium oxide particles, and/or have an inorganic or organic chemically modified surface. (ie titania-modified silica particles; silica-modified titania particles; 3-aminopropyltriethoxysilane modified silica particles).

In some embodiments, the glass-forming material may be, for example, but not limited to, a mixture of particles of different composition, such as, but not limited to, mixtures of silica particles and titania particles that are fused together to form silica-titania glass.

According to one embodiment, the glass-forming material may be a single composition glass-forming material that may not be in the form of particles. In some embodiments, dopants can be incorporated directly into polymers, such as, but not limited to, for example, but not limited to, silica, silica-titania containing polymers, silica-germanium oxide polymers, silica-aluminum oxide polymers, silica-boron trioxide polymers, etc. have.

The glass-forming material of the ink according to some embodiments may comprise larger molecules and/or polymers (linear or branched) prepared from small metal-containing organic precursors. Examples of the polymer include poly(dimethylsiloxane), silicone, diethoxysiloxane-ethyltitanate copolymer, polyhedral oligomeric silsesquioxane polymers and copolymers. Examples of large molecules include polyoxometalate clusters, oxoaloxometalate clusters. Designer Si/Ti containing polymers are prepared by acid-catalyzed hydrolysis of organosilicates and organotitanates such as tetraethylorthosilicate and titanium isopropoxide and additional transesterification steps if necessary. can be synthesized through Modifications of this process include the use of organometallic chemical components containing non-metal-oxygen bonds, such as (3-aminopropyl)triethoxysilane; doping by adding salts such as NaF, Cu(NO ₃ ) ₂ , Li ₂ CO ₃ directly to the polymer solution; doping by incorporation of metal species into polymer chains during acid-catalyzed hydrolysis; Replacing the major glass component (e.g., silicon (Si)), and the minor glass component (e.g., titanium (Ti)) with an alternative capable of linear polymerization, e.g., Ge, Zr, V, Fe include

According to some embodiments, the glass-forming material of the ink may include small metal-containing organic and/or inorganic precursors such as metal alkoxides, siloxanes, silicates, phosphates, chalcogenides, metal-hydroxides, metal salts, and the like. have. Examples may include silicon alkoxide, boron alkoxide, titanium alkoxide, germanium alkoxide. In some approaches, the glass-forming material of the ink may include titanium isopropoxide, titanium diisopropoxide bis(acetylacetonate), tetraethyl orthosilicate, zinc chloride, titanium chloride.

In one embodiment, the glass-forming material may be suspended in a solvent. In one embodiment wherein the glass-forming material is a polar and/or hydrophilic glass-forming material, the solvent is preferably a polar aprotic solvent. In one approach, the solvent may be the following pure components or mixtures thereof: propylene carbonate, dimethyl ether (eg tetra(ethylene glycol) dimethyl ether), and/or dimethylformamide. In another approach, the solvent may be a polar protic solvent such as alcohol and/or water. In one embodiment where the glass-forming material is hydrophobic, the solvent can be, but is not limited to, a non-polar solvent such as xylene, alkane.

According to one embodiment, the ink may be a combination of a glass-forming material and at least one second component that alters the properties of the heat treated glass structure. In some embodiments, the second component may be a dopant that alters properties. In other embodiments, more than one material property may be affected by the addition of a second component. In various embodiments, the second component may affect the material properties (eg, characteristics) of the resulting structure in terms of one or more of the following: optical, mechanical, magnetic, thermal, electrical, chemical characteristics, and the like.

In one approach, the second component may be in ionic form. In another approach, the second component may be a molecule. In yet another approach, the second component may be a particle.

In some embodiments, the ink may contain an effective amount of one or more second components capable of altering the properties of the heat treated glass structure. An effective amount of the second component is an amount that alters the properties of the heat treated glass structure, which, as will become apparent to one of ordinary skill in the art upon reading this description, is the concentration of the additive in accordance with the teachings herein without undue experimentation. It can be easily determined by varying the .

In one embodiment, the color of the resulting structure can be affected by the addition of one or more second components selected from the group: metal nanoparticles of various sizes (gold, silver), sulfur, metal sulfide (cadmium sulfide), Metal chlorides (gold chloride), metal oxides (copper oxides, iron oxides).

In one embodiment, the absorbance (linear or non-linear) of the resulting structure can be affected by the addition of one or more second components selected from the group: cerium oxide, iron, copper, chromium, silver, and gold.

In one embodiment, the refractive index of the resulting structure may be affected by the addition of one or more second components selected from the group: titanium, zirconium, aluminum, lead, thorium, barium.

In one embodiment, the dispersion of the resulting structure may be affected by the addition of one or more second components selected from the group: barium, thorium.

In one embodiment, the attenuation/optical density of the resulting structure may be affected by the addition of one or more second components selected from the group: alkali metals and alkaline earth metals.

In one embodiment, the photosensitivity of the resulting structure can be affected by the addition of one or more second components selected from the group: silver, cerium, fluorine.

In one embodiment, the electrical conductivity of the resulting structure can be affected by the addition of one or more second components selected from the group: alkali metal ions, fluorine, carbon nanotubes.

In one embodiment, the birefringence of the resulting structure, such as a birefringence with an index of refraction dependent on the polarization and propagation direction of the light imparted by the crystalline phase formed from the second component, is determined by the addition of at least one second component selected from the group can be affected by: titanium, zirconium, zinc, niobium, strontium, lithium, in combination with silicon and oxygen.

In one embodiment, the thermal conductivity of the resulting structure may be affected by the addition of one or more second components selected from the group: carbon nanotubes, metals.

In one embodiment, the thermal emissivity of the resulting structure may be affected by the addition of one or more second components selected from the group: tin oxide, iron.

In one embodiment, the coefficient of thermal expansion of the resulting structure may be affected by the addition of one or more second components selected from the group: boron oxide, titanium oxide.

In one embodiment, the glass transition temperature of the resulting structure can be affected by the addition of sodium carbonate as a second component.

In one embodiment, the melting point of the resulting structure may be affected by the addition of one or more second components selected from the group: sodium, aluminum, lead.

In one embodiment, the gain coefficient of the resulting structure can be affected by the addition of one or more second components selected from the group: rare earth ions (eg neodymium, erbium, ytterbium); transition metal ions (eg chromium).

In one embodiment, the light emission of the resulting structure can be affected by the addition of a second component. In another embodiment, the luminescence of the resulting construct may be affected by the addition of a second component. In yet another embodiment, the fluorescence of the resulting construct may be affected by the addition of a second component.

In one embodiment, the chemical reactivity of the resulting structure may be affected by the addition of one or more second components selected from the group: alkali metals, alkaline earth metals, silver.

In one embodiment, the density of the resulting structure may be affected by the addition of one or more second components selected from the group: titanium, zirconium, aluminum, lead, thorium, barium.

In one embodiment, the concentration of the second component in the ink can be changed during printing to form a composition gradient in the printed structure. In some approaches, the second component in the ink may form a compositional gradient in the final heat treated structure.

In some embodiments, the concentration of the second component in the ink may form a compositional change (eg, gradient, pattern, etc.) that may not be symmetric about any axis, eg, the pattern may form around the structure. may vary radially, the pattern may be formed as a complete 3D structure, etc., but is not limited thereto.

In some embodiments, the ink may contain an effective amount of one or more additional additives capable of performing a particular function. For example, additives may improve dispersion, phase stability, and/or network strength; be able to control and/or change the pH; can modify rheology; reduce crack formation during drying; may assist in sintering or the like, but is not limited thereto. An effective amount of an additive is an amount that imparts a desired function or result, and as will become apparent to one of ordinary skill in the art upon reading this description, various concentrations of the additive may be varied in accordance with the teachings herein without undue experimentation. This can be easily determined.

In some embodiments, the ink may include one or more of the following additives to improve dispersion: a surfactant (eg 2-[2-(2-methoxyethoxy)ethoxy]acetic acid (MEEAA)) , polyelectrolytes (eg polyacrylic acid), inorganic acids (eg citric acid, ascorbic acid).

In one embodiment, the ink contains additives (eg boric anhydride (B ₂ O ₃ )) to improve phase stabilization (ie to prevent phase/composition separation, which may or may not be crystalline phase separation). may include Another example is ZnO, which can act as a phase stabilizer for alkali silicates.

In one embodiment, the ink may include additives (eg boric anhydride B ₂ O ₃ ) to inhibit crystallization. Other crystallization inhibitors include Al ₂ O ₃ and Ga ₂ O ₃ .

In one embodiment, the ink may include additives (eg polydimethylsiloxane) to strengthen the network.

In one embodiment, the ink may include one or more of the following additives to control the pH: organic acids, inorganic acids, bases (eg acetic acid, HCl, KOH, NH ₄ OH).

In one embodiment, the ink may include one or more of the following additives to modify the rheology: a polymer (eg cellulose, polyethylene glycol, polyvinyl alcohol); surfactants (eg MEEAA, sodium dodecyl sulfate, glycerol, ethylene glycol); metal alkoxides (eg titanium diisopropoxide bis(acetylacetonate)).

In one embodiment, the ink may include one or more of the following additives as drying aids to enhance crack resistance and/or reduce crack formation during drying: polymer (eg polyethylene glycol, polyacrylate), crosslinking monomers or polymers and crosslinking reagents (eg polyethylene glycol diacrylate (PEGDA)).

In one embodiment, the ink may include additives as sintering aids. The sintering aid improves the sintering/densification process. In the case of glass, sintering aids can lower the viscosity of the material that is sintered into glass. For example, boric anhydride (B ₂ O ₃ ) may be included as a sintering aid.

In various embodiments, formulations of glass-forming inks (ie, glass-forming materials) are optimized for a combination of the following factors: printability (depending on the 3D printing method), crack resistance, and sintering to transparency . In some approaches, the volumetric loading of the formulation of the glass-forming ink is optimized. In some approaches, the characteristics of the composition gradient of the glass-forming material can be optimized.

According to one embodiment, the blend of glass-forming materials comprises a glass-forming inorganic species in the range of from about 5 vol % to about 50 vol % of the total volume; solvent in the range of about 30 vol % to about 95 vol %; a second component(s) (ie a dopant) in the range of 0 wt % to about 20 wt %; and 0 wt % to about 10 wt % of additive(s).

Example Formulation 1 of Ink

5 to 15 vol% fumed silica (Cabosil EH-5 or Cabosil OX-50)

30 to 95 vol% tetraethylene glycol dimethyl ether

0-20 wt% titanium diisopropoxide bis(acetylacetonate)

0 to 6 wt % ethylene glycol

0 to 2 wt % poly(dimethylsiloxane)

Example formulation 2 of ink

75-95 vol % silica-titania-containing polymer

10 to 25 vol% tetraethylene glycol dimethyl ether

0 to 10 vol% H ₂ O for prehydrolysis

Example formulation 3 of ink

5-20 vol % 25-nm titania-coated silica particles

25 to 45 vol % propylene carbonate

25 to 45 vol% tetraethylene glycol dimethyl ether

0 to 5 wt % MEEAA

According to one embodiment, the concentration of the second component in the ink can be varied during printing to form a compositional gradient in the structure and thus the final heat treated structure.

In one embodiment, the temperature of the ink may be less than about 200° C. during printing.

In one embodiment, method 100 includes drying the formed structure to remove sacrificial material, wherein drying is performed prior to heat treatment of the formed structure. Ideally, the fully formed structure is dried in a single process.

According to one embodiment as shown in FIG. 1 , method 100 includes operation 104 comprising heat-treating the formed structure to convert the glass-forming material to glass.

In one embodiment, the method comprises additional processing of the heat treated glass structure. In one approach, a method includes grinding a heat treated glass structure. In another approach, a method includes polishing a heat treated glass structure. In yet another approach, the method includes grinding and polishing a heat treated glass structure.

In one embodiment, the heat treated glass structure may be in the form of fibers.

In another embodiment, the heat treated glass structure may be in the form of a sheet.

In one embodiment, the heat treated glass structure may be a three-dimensional monolith.

In another embodiment, the heat treated glass structure may be in the form of a coating on a substrate such as a part, tool, or the like.

2A and 2B show methods 200 and 250 for making an optical glass member having a user-customizable composition profile according to one embodiment. Optionally, methods 200 and 250 may be implemented in connection with features from any of the other embodiments listed herein, such as those described with respect to the other figures. However, of course, these methods 200 and 250 and others presented herein may be used in a variety of applications and/or permutations that may or may not be specifically described in the exemplary embodiments listed herein. Additionally, methods 200 and 250 presented herein may be used in any desired environment.

An exemplary embodiment of a method 200 for making a single component silica glass is shown in FIG. 2A. According to one embodiment, the method for printing the ink comprises DIW printing as shown in steps 222 and 224 . DIW is a 3D printing process based on the extrusion of viscoelastic materials. Pneumatic or positive displacement forces the ink 202 through a small nozzle 208 . In some approaches, the nozzle 208 is computer controlled and has three degrees of freedom (x, y and z). In another approach, the nozzle 208 can be enlarged to have six axes for printing. Nozzles 208 may be arranged to extrude ink in a controlled spatial pattern.

In steps 222 and 224, filaments 212 of rheologically tuned glass-forming DIW ink 202, containing glass-forming species, are deposited into a predetermined geometry by DIW, weakly bonded and A porous amorphous low-density shaped body (LDF) 214 having a mesh-like shape is formed. In some approaches, the extruded filaments 212 set quickly to become the LDF 214 . In some approaches, LDF 214 may be referred to as a green body, a glass-forming species, or the like. Glass-forming species may be introduced as precursors and/or colloids/particles. In some approaches, the glass-forming DIW ink 202 may be a colloidal silica ink.

According to one embodiment, the formulation of glass-forming DIW inks is optimized for printability, drying/bakeout, and sintering. Formulations of glass-forming DIW inks can be optimized for printability in terms of shear thinning, flow (rectification) ability, shape retention (shape retention) ability, low agglomeration, long print time, stable pot life (stability), etc. . Formulations of glass-forming DIW inks can be optimized for drying in terms of handling resistance, crack resistance, low/uniform shrinkage, porosity suitable for organic removal, and the like. Formulations of glass-forming DIW inks can be optimized for sintering in terms of crack resistance, low/uniform shrinkage, densification/translucency capability, low tendency to phase separation, and the like.

According to one embodiment, step 222 includes a glass-forming DIW ink 202 that is extruded through a nozzle 208 that deposits the filaments 212 as a single layer on the substrate 210 .

Step 224 of method 200 includes building a layer on top of a layer of glass-forming DIW ink 202 to form LDF 214 . 3A shows an image of colloidal silica ink being extruded onto a substrate.

The LDF 214 may be processed through a number of steps to solidify the LDF 214 and convert it to a heat treated glass body 216 .

Optionally, the LDF 214 may be further machined, either before or after drying, to further change the composition of the part. In some approaches, additional processing may include diffusion, leaching, etching, and the like. In another approach, the additive processing may include light, sound, vibration, or a combination thereof to alter the characteristics of the printed object. In other approaches, chemical treatment prior to closing the pores of the LDF through heat treatment may limit the optical quality of the resulting glass body.

In step 226, the LDF may be treated by drying, calcining (ie removal of residual solvent/organic at elevated temperature), or the like. During drying, the liquid/solvent phase may be removed. The LDF 214 may be separated from the substrate 210 on which the LDF 214 is printed. In some approaches, drying step 226 may include standing at a temperature below the boiling point of the solvent for hours to weeks.

In some embodiments, processing step 226 may include a heating step (ie, burnout) at a lower temperature to remove organics as well as any residual and/or adsorbed water/solvent phase. In some approaches, the incineration step may include standing at 250 to 600° C. for 0.5 to 24 hours.

In some embodiments, processing step 226 may include heating the LDF 214 under an alternate gas atmosphere to chemically convert the surface (eg, to convert free surface hydroxyls to dehydrated siloxane). have. In some approaches, processing step 226 may include heating LDF 214 under an oxidizing gas atmosphere (eg, O ₂ gas). In another approach, processing step 226 may include heating the LDF 214 under a reducing gas atmosphere (eg, H ₂ gas). In other approaches, processing step 226 may include heating LDF 214 under a non-reactive gas atmosphere (eg Ar, He). In other approaches, processing step 226 may include heating LDF 214 under a reactive gas atmosphere (eg, N ₂ , Cl ₂ ). In other approaches, processing step 226 may include heating LDF 214 under vacuum.

In some embodiments, processing step 226 may also include compacting the parts of LDF 214 using uniaxial pressure or isotropic pressure (ie, reducing porosity) to create a compact body. In some approaches, machining step 226 may also include compressing the part of LDF 214 under vacuum (ie, reducing porosity).

3B shows an image of the dried LDF.

According to one embodiment, the method includes heat treating the dried LDF 214 to close the remaining pores to form a consolidated transparent glass part, as shown in step 228 of FIG. 2A . In some approaches, the compact body of LDF can be heat treated.

The thermal treatment step 228 may include sintering, which completely densifies the LDF 214 (ie, glass-forming inorganic species) at an elevated temperature into a condensed solid glass body 216 . In some approaches, sintering the LDF may include standing at 500-1600° C. for minutes to hours. The temperature for sintering depends on the material composition and the initial inorganic loading and the porosity of the LDF. In some approaches, sintering of the LDF may involve the simultaneous use of applied pressure. In some approaches, the thermally treating step 228 may be performed at various ambient conditions. In another approach, the thermal treatment step 228 may be performed under vacuum.

In some embodiments, the heat treated glass body 216 may be a monolithic glass structure. 3C shows an image of the monolithic glass structure after heat treatment of the LDF shown in FIG. 3B. In some embodiments, the resulting consolidated glass body 216 may retain the characteristics of the ink 202 that may have been imparted during DIW printing (steps 222 and 224).

In one embodiment, the consolidated glass body 216 will have the physical characteristics of the LDF 214 including spiral, arcuate, and/or straight ridges along one surface of the glass body 216 . can

In one embodiment, the glass body 216 is post-processed in a post-processing step 230 to obtain the desired result of the final optical body 218 polished through techniques such as, for example, grinding and/or polishing. Appearance and/or surface finish may be achieved. In one embodiment, since the polished optical body 218 is a polished object by 3D printing and heat treatment, the properties of the LDF 214 are maintained and not lost by polishing. In one embodiment, the polished optical body 218 is a polished monolithic glass structure.

In some approaches, the glass body 216 may be treated as bolted glass, allowing it to eliminate any traces of the printing process by conventional techniques known in the art. In another approach, the glass body 216 retains properties that can only be achieved by the printing process described herein, even after post-processing.

A schematic representation of a method 250 for forming gradients and/or spatial patterns in a glass product, in accordance with one embodiment, is shown in FIG. 2B . In other embodiments, compositional changes (e.g., gradients, patterns, etc.) that may not be symmetric about any axis may be formed by the method, e.g., the pattern changes radially around the structure. or the pattern may be formed as a complete 3D structure, etc., but is not limited thereto.

In one approach, gradient index (GRIN) glasses can be formed by the method. Printing of GRIN glass involves printing porous monoliths, where the features of the formation of LDFs result in space filling, high aspect ratios, and advantageous modulus/viscosities as revealed by spanning. The method may also include matching the rheology of the two DIW inks desired to form the gradient. In some embodiments, two, three, four, etc. inks may be combined via mixing prior to extruding the filaments onto the substrate.

According to one embodiment, during the DIW printing steps 232 , 234 , the filament composition 213 can be adjusted during printing by adjusting the flow rates of the individual streams to introduce a desired composition change at desired sites within the LDF 214 . have.

In some approaches, different inks 203 , 204 may be introduced separately to form LDF 215 . As shown in the schematic depiction of the side view in FIG. 4A, in one approach, a monolithic glass structure 400 (LDF 215 in FIG. 2B) having the physical characteristics of forming by 3D printing is a monolithic glass structure. It may include a refractive index gradient of the monolithic glass structure 400 along the axial direction of 400 . The axis 408 direction is perpendicular to the stacking plane 410 .

Referring again to FIG. 2B , the glass structure is formed as an LDF (LDF 215 in FIG. 2B ), which may be an extruded second glass-forming ink 204 after a first glass-forming ink 203 has been extruded. do. The resulting glass structure 400 in FIG. 4A has a first glass 403 and a second glass 404 from a first glass-forming ink 203 and a second glass-forming ink 204, respectively.

Moreover, the resulting glass structure 400 in FIG. 4A is formed between a first glass 403 formed from a glass-forming material and a second glass 404 formed from a second glass-forming material having a different composition from the glass-forming material. may include an interface 406 of In some approaches, the first glass 403 and the second glass 404 may be immiscible with each other because the second glass-forming material may not migrate across the interface to the first glass-forming material or vice versa. Because.

In one embodiment, the interface 406 is oriented substantially along the lamination plane 410 of the monolithic glass structure 400 such that the monolithic glass structure is immediately adjacent to the interface, the first glass 403 being two parts having different compositions. ) and the second glass 404 can be divided.

As shown in Figures 5A-5D, two different inks, silica and silica with 20 nm gold nanoparticles, were used to form compositional changes that resulted in changes in material properties in the heat treated final structures. 5A and 5B show the formation of an axial step in absorption in the heat treated final structure. As shown in FIG. 5A , the LDF was formed to have a texture change, where a first ink silica was used to form a portion of the LDF (bottom of the LDF in FIG. 5A ), and then the ink was used to form a second ink, silica/ was replaced with gold nanoparticle ink (top of LDF in FIG. 5A). The LDF was then sintered during heat treatment (step 238 in FIG. 2B ) to solidify into glass. The resulting monolithic glass structure with an absorbance gradient along the axial direction is shown in FIG. 5B , where the silica/gold nanoparticle portion of the glass is at the top in FIG. 5B .

The physical characteristics of the monolithic glass structure 217 in one embodiment include a gradient comprising two or more glass-forming materials such that the interface between the first glass-forming material and the second glass-forming material is uniform. . As shown in Figure 5A, an interface exists between the upper glass-forming material (silica/gold nanoparticles) and the lower material (silica). Moreover, the first glass-forming material (silica) does not migrate to the second glass-forming material (silica/gold nanoparticles), conversely, the second glass-forming material (silica/gold nanoparticles) does not migrate to the first glass-forming material ( silica).

The embodiments described herein could not be achieved using prior art methods for 3D printing optical glass because in prior art methods it is difficult to control the thermal gradient during 3D printing, and/or the interfaces between the filaments are non-uniform and or because it is not possible to incorporate a large number of materials into the green body or LDF.

In another approach, a smooth composition change can be formed by blending ink streams from different inks 203 , 204 inline through active mixing using a mixing paddle 206 near the tip of the nozzle 208 . . As shown in the schematic depiction of the top view of FIG. 4B , in one approach, a monolithic glass structure 420 (LDF 215 of FIG. 2B ) having the physical characteristics of formation by 3D printing has a refractive index, or another material. A characteristic, such as a gradient in absorbance, may include along the radial direction of the monolithic glass structure 420 . The radial 412 direction is in any direction along the stacking plane 410 . Referring again to FIG. 2B, the glass structure is formed as an LDF with a radial refractive index step (LDF 215 in FIG. 2B), where the two inks 203 and 204 in FIG. 2B were blended in-line as an ink stream. The resulting glass structure 420 in FIG. 4B has first glass 414 and second glass 413 from first glass-forming ink 203 and second glass-forming ink 204, respectively.

Moreover, the resulting glass structure 420 in FIG. 4B is formed between a first glass 414 formed from a glass-forming material and a second glass 413 formed from a second glass-forming material having a composition different from the glass-forming material. an interface 416 of In some approaches, the first glass 414 and the second glass 413 may not be miscible with each other because the second glass-forming material may not migrate across the interface to the first glass-forming material or vice versa. Because.

In one embodiment, the interface 416 is oriented substantially perpendicular to the stacking plane 410 of the monolithic glass structure 420 , thereby rendering the monolithic glass structure 420 into two groups of different compositions in the immediate vicinity of the interface 416 . It can be divided into a first glass 413 and a second glass 414 that are parts.

According to one embodiment, two different inks can be used to print the texture change of the LDF that results in a material property called a radial absorbance step on the heat treated final structure. As shown in Figures 5C and 5D, a radial absorbance step was printed using a first ink, silica, and a second ink, silica/gold nanoparticles, where the two inks were blended in-line as an ink stream. FIG. 5C shows an LDF object having silica/gold nanoparticle ink in the center of the LDF and silica ink in the outer part of the LDF. The resulting monolithic glass structure with an absorbance gradient along the radial direction is shown in FIG. 5D .

Compositional variations may not be limited to axial and/or radial gradients (such as those achieved by diffusion techniques), but rather may be used to form arbitrary profiles in the LDF.

Composition changes in the LDF 215 may result in various material properties within the formed glass 217 . Examples of material properties that may be affected by compositional changes in LDF 215 are described in greater detail above and may include, but are not limited to: absorbance, transmittance, refractive index, Dispersion, scattering, electrical conductivity, thermal conductivity, coefficient of thermal expansion, gain factor, glass transition temperature (Tg) melting point, light emission, fluorescence, chemical reactivity (eg etch rate), density/porosity.

As shown in FIG. 2B , the DIW printing in steps 232 , 234 may include forming the LDF 215 , according to one embodiment. The LDF begins as a single layer on the substrate 210 in a first step 232 of DIW printing. As DIW printing continues at step 234, the LDF 215 may be formed layer by layer until the desired LDF 215 (ie, the green body) is formed.

In some embodiments, the formation of LDFs with a single composition (method 200) or formation of LDFs with multiple compositions (eg, gradients) (method 250) may comprise fused layered modeling (FDM). . FDM uses a thermoplastic filament, which can be a composite mixture of several materials joined using a mixing paddle, similar to a DIW ink mixture (see steps 232-234 in Figure 2B). The resulting filament can be extruded through a heated nozzle to form an LDF on the substrate as shown in steps 222-224 or 232-234 of FIGS. 2A and 2B, respectively. The heated nozzle partially heats the filament for extrusion at a temperature in the range of about 150°C to 200°C. In some approaches, the sacrificial support material may be extruded using a second nozzle to provide support for the glass-forming material to be extruded by the mixing nozzle. In some approaches, the polymer and/or support material of the extruded filaments may be removed after formation of the LDF.

In various embodiments, the LDF can be formed into complex shapes, such as, but not limited to, cones, corkscrew patterns, cylinders, and the like.

To solidify the LDF 215 and convert it to a heat treated glass body 217 , the LDF 215 may be processed in multiple steps.

Once the LDF 215 is formed, the LDF 215 may be dried and/or further processed, as described above with respect to step 226 of the method 200 in FIG. 2A .

2B, according to one embodiment, step 238 of method 250 includes heat treating dried LDF 215 to close the remaining pores and form a consolidated transparent glass part. The resulting solidified glass body 217 may retain compositional variations that may have been imparted during DIW printing (steps 232 and 234 ).

In one embodiment, the consolidated glass body 217 may have the physical characteristics of the LDF 215 including helical, arcuate, and/or straight curvatures along one surface of the glass body 217 .

According to one embodiment, the glass body 217 is further processed in a post-processing step 240 to obtain the desired final optical body 220 polished through techniques such as, for example, grinding and/or polishing. Appearance and/or surface finish may be achieved. In one embodiment, since the polished optical body 220 is a polished object by 3D printing and heat treatment, the properties of the LDF 215 are maintained and not lost by polishing. In one embodiment, the polished optic 220 is a polished monolithic glass structure.

The various embodiments described herein, in addition to silica-based glasses, include a variety of (mainly) phosphate-based glasses, borate glasses, germanium oxide glasses, fluoride glasses, aluminosilicate glasses, and chalcogenide glasses. ) can be extended to amorphous inorganic organic materials.

Heat Treatment Example 1

The printed monolithic silica or silica-titania green body (25 mm diameter, 5 mm thickness) is placed on a 100° C. hot-plate. After 3 hours, the printed green body is separated from the substrate. The green body is then dried in a box furnace at 100° C. for 110 hours. Then, the liquid-free green body was heated to 600 DEG C at a heating rate of 10 DEG C/min and left still for 1 hour to incinerate the remaining organic components. The green body is then heated from 100° C./hr to 1000° C. and held under vacuum for 1 hour. Finally, the parts are sintered in a furnace preheated to 1500° C. for 3 to 10 minutes. The parts are then withdrawn and rapidly cooled to room temperature. All non-vacuum processing steps are performed in air.

Heat Treatment Example 2

A printed monolithic silica green body, composed of 25-nm diameter silica or silica-titania particles (25 mm diameter, 5 mm thickness), is heated in a box furnace at 3° C./h to 75° C. When the oven reaches 75° C., the printed green is separated from the substrate. The green body is then dried in a drying oven at 75° C. for 120 hours. Then, the liquid-free green body was heated to 600 DEG C at a heating rate of 1 DEG C/min and left still for 1 hour to incinerate the remaining organic components. Finally, the parts are sintered in a furnace preheated to 1150° C. for 1 hour. The parts are then withdrawn and rapidly cooled to room temperature. All non-vacuum processing steps are performed in air.

Experiment

6A-6F are images of printed parts made with Ink Formulation 3 (as described above). 6A-6C are images of printed parts formed to have a silica-only composition. 6A is an image of a green body formed after printing. Fig. 6B is an image of the green body of Fig. 6A after drying. Fig. 6C is an image of the dried green body of Fig. 6B after consolidation.

6D-6F are images of printed parts formed to have a silica-titania composition. 6D is an image of a green body formed after printing. Fig. 6E is an image of the green body of Fig. 6D after drying. FIG. 6F is an image of the dried green body of FIG. 6E after setting.

7A is a plot of refractive index profile (y-axis) versus titania (TiO ₂ ) concentration in glass as a result (wt%, x-axis). The glass made with Ink Formulation 1 (as described above) is shown on the plot as diamond (♦, solid line) and comparable to commercial silica (▲) and silica-titanate glass (○, □) (dotted line). It has refractive index fluctuations. FIG. 7B is represented by diamonds (♦) in FIG. 7A at various wt% concentrations of TiO ₂ (2 wt%, 4 wt%, 5 wt%, 6 wt%, 8 wt%, 9 wt%, 10 wt%). It is an image of the resulting glass structure formed from an ink formulation.

8 is a plot of a heat treatment profile of a process for forming a cured, printed part using Ink Formulation 1 (as described above). The volumetric shrinkage (V _ink ) of the structure at each step during the heat treatment process is indicated next to the image of the structure.

9A is an optical image of a gradient refractive index silica-titania glass lens prepared by direct ink writing of an LDF while blending the two inks inline at the printhead at the ratio required to stack a radial gradient of TiO ₂ concentration. Two inks from Ink Formulation 1 (described above) were used, Ink A contained 0% titanium alkoxide and Ink B sufficient titanium alkoxy to result in 1.6 wt% TiO ₂ in the condensed final glass. contains de. The glass was set using the heat treatment profile shown in FIG. 8 and then polished using ceria pad polishing. FIG. 9B is a surface-corrected interferogram showing how the refractive index changes in the mass of material shown in the image of FIG. 9A. The refractive index is highest at the center where the TiO ₂ composition is highest, and the lowest at the edge where the TiO ₂ concentration is lowest. The line across the center is a parabolic curve of the refractive index change across the center, as shown by the inset plot of FIG. 9B (y-axis is δn/(n ₀ −1), x-axis is distance (mm)). , suggesting that the part can function as a lens. 9C is an image at 300-μm focus from the lens, with a focal length of 62 cm.

FIG. 10A is an optical image of a composite glass composed of a gold-doped silica glass core and an undoped silica glass cladding, prepared by ink recording composition changes directly onto an LDF. Two silica inks were used, with one ink containing gold nanoparticles. 10B is a plot of absorbance as a function of wavelength of light, with each spectrum corresponding to a marked location across the glass. The peak at 525 nm was due to absorbance from the gold nanoparticles. 10C is a plot of absorbance (y-axis) at 525 nm versus positions along the glass surface (x-axis, where position 0 is the center of the glass). The plot in FIG. 10C shows that the absorbance at 525 nm was tuned in this glass. The measured spot size exceeded the average ˜1 mm diameter spot.

purpose

The various embodiments described herein provide active or passive optical glass members (eg lenses, corrector plates, windows, screens, collectors) with specialized composition and material properties for both commercial or government applications. , waveguides, mirror blanks, sensors, etc.). These methods include absorbance, transmittance, refractive index, dispersion, scattering, electrical conductivity, thermal conductivity, coefficient of thermal expansion, gain coefficient, glass transition temperature (Tg), melting point, light emission, fluorescence, chemical reactivity (e.g. etch rate), or to introduce ions, molecules, or particles at any (i.e. tailored) site within a glass member (monolith, film, or amorphous-shaped body) to achieve spatially varying material properties, including density/porosity, within the glass. can be used

Various embodiments described herein provide methods for making complex 3D and controlled colored glass artworks, ornaments, and the like. Control of the dopant of silver and gold nanoparticles allows control of the reflective and transmissive properties of the artwork.

Additional embodiments include active or passive optical glass members useful for lenses, calibration plates, windows, screens, collectors, waveguides, mirror blanks, sensors, and the like, as well as non-optical glass members useful in conventional applications.

The inventive concepts disclosed herein have been presented to illustrate their numerous features in a plurality of illustrative scenarios, embodiments, and/or implementations. In general, it is to be understood that the disclosed concepts are to be regarded as modular and may be implemented as any combination, permutation, or integration thereof. In addition, any modifications, changes, or equivalents of the features, functions, and concepts disclosed herein that those skilled in the relevant art will come to upon reading this description should also be considered to fall within the scope of the present disclosure.

While various embodiments have been described above, it is to be understood that they have been presented by way of example only and not limitation. Accordingly, the scope and scope of the embodiments of the present invention should not be limited by any of the exemplary embodiments described above, but should be limited only in accordance with the claims that follow and their equivalents.

Claims (36)

particles of glass-forming material, which are glass precursors;
a second component for forming a compositional gradient of the second component within the glass-forming material; and
menstruum
An ink composition for an extrusion-based additive manufacturing method comprising: The ink composition of claim 1 , wherein the glass-forming material comprises a single composition of inorganic particles. 3. The ink composition of claim 2, wherein the single composition is selected from the group consisting of fumed silica, colloidal silica, rudox colloidal silica dispersion, titania particles, zirconia particles, alumina particles, metal chalcogenide particles. The ink composition of claim 1 , wherein the glass-forming material comprises particles of mixed composition. 5. The ink composition of claim 4, wherein the particles of the mixed composition comprise particles selected from the group consisting of silica-titania particles, silica-germanium oxide particles, and particles having an inorganic or organic chemically modified surface. The ink composition of claim 1 , wherein the glass-forming material comprises silica-germanium oxide particles. The method of claim 1 , wherein the glass-forming material comprises a polymer selected from the group consisting of silica polymers, silica-titania containing polymers, silica-germanium oxide polymers, silica-aluminum oxide polymers, and silica-boron trioxide polymers. ink composition. The ink composition of claim 1 , wherein the glass-forming material comprises a silica-germanium oxide polymer. The ink composition of claim 1 , wherein the glass-forming material of the ink comprises a metal-containing organic precursor and/or a metal-containing inorganic precursor. 10. The ink composition of claim 9, wherein the precursor is selected from the group consisting of metal alkoxides, siloxanes, silicates, phosphates, chalcogenides, metal-hydroxides, and metal salts. The ink composition of claim 1 , wherein the second component is used in an effective amount to alter the properties of a glass structure formed using the ink. 12. The ink composition of claim 11, wherein the second component affects a property selected from the group consisting of optical properties, mechanical properties, magnetic properties, thermal properties, electrical properties, and chemical properties. 12. The ink composition of claim 11, wherein the second component is a color-altering component selected from the group consisting of metal nanoparticles, sulfur, metal sulfides, metal chlorides, and metal oxides. 12. The ink composition of claim 11, wherein the second component is an absorbance modifying component selected from the group consisting of cerium oxide, iron, copper, chromium, silver, and gold. 12. The ink composition according to claim 11, wherein the second component is a refractive index modifying component selected from the group consisting of titanium, zirconium, aluminum, lead, thorium, and barium. 12. The ink composition of claim 11, wherein the second component is a dispersion modifying component selected from the group consisting of barium and thorium. 12. The ink composition of claim 11, wherein the second component is an attenuating and/or optical density modifying component selected from the group consisting of alkali metals and alkaline earth metals. 12. The ink composition of claim 11, wherein the second component is a photosensitivity modifying component selected from the group consisting of silver, cerium, and fluorine. 12. The ink composition of claim 11, wherein the second component is an electrical conductivity modifying component selected from the group consisting of alkali metal ions, fluorine, and carbon nanotubes. 12. The ink composition of claim 11, wherein the second component is a birefringence modifying component selected from the group consisting of titanium, zirconium, zinc, niobium, strontium, lithium in combination with silicon and oxygen. 12. The ink composition of claim 11, wherein the second component is a thermal conductivity modifying component selected from the group consisting of metals and carbon nanotubes. 12. The ink composition of claim 11, wherein the second component is a thermal emissivity modifying component selected from the group consisting of tin oxide and iron. 12. The ink composition according to claim 11, wherein the second component is a thermal expansion coefficient modifying component selected from the group consisting of boron oxide and titanium oxide. 12. The ink composition of claim 11, wherein the second component is sodium carbonate for changing the glass transition temperature of the structure. 12. The ink composition of claim 11, wherein the second component is a melting point modifying component selected from the group consisting of sodium, aluminum, and lead. 12. The ink composition of claim 11, wherein the second component is a gain factor modifying component selected from the group consisting of rare earth ions and transition metal ions. 12. The ink composition of claim 11, wherein the second component affects a property selected from the group consisting of light emission, luminescence, and fluorescence. 12. The ink composition of claim 11, wherein the second component is a chemical reactivity modifying component selected from the group consisting of alkali metals, alkaline earth metals, and silver. 12. The ink composition of claim 11, wherein the second component is a density modifying component selected from the group consisting of titanium, zirconium, aluminum, lead, thorium, and barium. The method of claim 1 , for causing an effect selected from the group consisting of improving dispersion, improving phase stability, improving network strength, controlling pH, changing pH, modifying rheology, reducing crack formation during drying, inhibiting crystallization, and assisting sintering. An ink composition further comprising an effective amount of an additive. The ink composition of claim 1 , further comprising an effective amount of an additive to improve dispersion selected from the group consisting of surfactants, polyelectrolytes, and inorganic acids. The ink composition of claim 1 , further comprising an effective amount of an additive to improve phase stabilization. The ink composition according to claim 1, further comprising an additive in an effective amount for inhibiting crystallization selected from the group consisting of B ₂ O ₃ , Al ₂ O ₃ and Ga ₂ O ₃ . 2. The method of claim 1, wherein the glass-forming material is present in a range from 5 vol% to 50 vol%, based on the total volume of the ink composition, and the solvent is present in a range from 30 vol% to 95 vol%, based on the total volume of the ink composition. one or more second components present in a range of 0 wt% to 20 wt% based on the total volume of the ink composition, and present in a range of 0 wt% to 10 wt% based on the total volume of the ink composition An ink composition further comprising one or more additives. a glass-forming material comprising a single composition of inorganic particles;
a second component for forming a compositional gradient of the second component within the glass-forming material; and
menstruum
includes,
wherein the single composition is selected from the group consisting of fumed silica, colloidal silica, rudox colloidal silica dispersion, titania particles, zirconia particles, alumina particles, and metal chalcogenide particles,
An ink composition for an extrusion-based additive manufacturing method. delete

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