WO2019046650A1

WO2019046650A1 - Glass ceramic composites with metal network and manufacturing methods for glass ceramic composites

Info

Publication number: WO2019046650A1
Application number: PCT/US2018/048962
Authority: WO
Inventors: Monika Backhaus-Ricoult; Melisande Isabelle CHEVAUCHERIE; Marie Jacqueline Monique Comte
Original assignee: Corning Incorporated
Priority date: 2017-08-31
Filing date: 2018-08-30
Publication date: 2019-03-07

Abstract

A glass ceramic composite includes a plurality of cells forming a glass ceramic microstructure and a ghost network surrounding and separating individual cells of the plurality of cells, wherein the ghost network is a discontinuity in the microstructure, and wherein metal decorates at least a portion of the ghost network. A method for manufacturing the glass ceramic composite includes forming a glass powder comprising at least one oxide of a metal selected from Groups VI-XII of the periodic table into a green body of desired shape, ceramming the green body by firing at a heating rate from 100 °C/ hour to 350 °C/hour to a hold temperature from 600 °C to 1200 °C and holding the green body at the hold temperature for a duration from 1 hour to 20 hours.

Description

GLASS CERAMIC COMPOSITES WITH METAL NETWORK AND

MANUFACTURING METHODS FOR GLASS CERAMIC COMPOSITES

[0001] This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application Serial Nos. 62/552,622, filed on August 31 , 2017 and 62/577,455 filed on October 26, 2017, the contents of both are relied upon and incorporated herein by reference in their entirety.

BACKGROUND

FIELD

[0002] The present specification generally relates to glass ceramics and, more specifically, to glass ceramics having metal network structures.

TECHNICAL BACKGROUND

[0003] Glass ceramics have previously been produced from many different bulk glasses by subjecting them to partial or full crystallization in a ceram cycle. Products made from those glass ceramics include, for example, cooking ware, radomes, machinable materials, white or black smart phone platelets, cook tops, and fire-resistant windows. Glass ceramics cannot only be formed by a homogeneous nucleation and crystallization across the entire body of the bulk glass, but also may be formed by surface nucleation and crystal growth from the surface into the bulk glass. The latter typically leads to formation of crystalline surface scales and lacks uniformity when applied to large parts. However, uniform crystallization can be obtained when starting with a green-formed glass powder (frit).

[0004] While cordierite glass ceramics have been used as substrates and via fill components for electronic packaging, cordierite glass ceramics do not meet the future needs of very thin sheet, small via size, and small via interspacing. And, evolving technology drives needs for glass-ceramic substrate materials that contain a large number of conductive paths in an insulating material that allow one to make substrate plates with conductive paths between the two plate surfaces. Currently boards with electrical through-vias are processed by drilling (mechanical, laser, etching and other processes) holes and filling them with metal (such as, for example, copper by electrodeposition, mechanical plugging, vapor deposition, tape casting mixed pastes of metallic copper and cordierite glass ceramic precursor glass beads). However, these processes are limited in achievable via interspacing. Namely, desirable via interspaces of less than 10 μm seem not to be achievable. In addition the process requires many processing steps and is therefore inefficient and expensive.

SUMMARY

[0005] According to one embodiment a glass ceramic composite comprises a plurality of cells forming a glass ceramic microstructure and a ghost network surrounding and separating individual cells of the plurality of cells, wherein the ghost network is a discontinuity in the microstructure, and wherein metal decorates at least a portion of the ghost network.

[0006] In another embodiment, a method for manufacturing a glass ceramic composite comprises: forming a glass powder comprising at least one oxide of a metal selected from Groups Vl-Xll of the periodic table into a green body of desired shape; ceramming the green body by firing the green body using a heating rate from greater than or equal to 100 °C/ hour to less than or equal to 350 °C/hour to a hold temperature from greater than or equal to 600 °C to less than or equal to 1200 °C and holding the green body at the hold temperature for a duration from greater than or equal to 1 hour to less than or equal to 20 hours. The glass ceramic composite comprises: a plurality of cells forming a glass ceramic microstructure and a ghost network surrounding and separating individual cells of the plurality of cells, wherein the ghost network is a discontinuity in the microstructure, and wherein metal decorates at least a portion of the ghost network.

[0007] In one or more embodiments, an electronic device, comprises: electrical components; and a glass ceramic composite component electrically connected to the electrical components. The glass ceramic composite comprises: a plurality of cells forming a glass ceramic microstructure and a ghost network surrounding and separating individual cells of the plurality of cells, wherein the ghost network is a discontinuity in the microstructure, and wherein metal decorates at least a portion of the ghost network.

[0008] Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description which follows, the claims, as well as the appended drawings.

[0009] It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate the various embodiments described herein, and together with the description serve to explain the principles and operations of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1A is a schematic illustration of green compacted/pressed glass frit particles before the sintering/densification step according to one or more embodiments disclosed and described herein;

[0011] FIG. IB is a schematic illustration of a glass ceramic after the sintering/densification step, showing boundary lines according to one or more embodiments disclosed and described herein;

[0012] FIG. 2A is a schematic illustration of a green-compact of metal-precursor or metal-decorated/coated glass frit particles before the sintering/densification step according to one or more embodiments disclosed and described herein;

[0013] FIG. 2B is a schematic illustration of a glass ceramic after the sintering/densification step, having a metal decoration along the ghost network according to one or more embodiments disclosed and described herein; [0014] FIG. 2C is a schematic illustration of a glass ceramic after the sintering/densification step, containing larger amount of metal in the metal network that also fills large interstices between cells of the glass ceramic, such as present at the triple points according to one or more embodiments disclosed and described herein;

[0015] FIGS. 3A - 3D graphically illustrate particle size distributions of coarse frit of lithium aluminum silicate and fine frit of cordierite, lithium aluminum silicate, and calcium aluminum silicate according to one or more embodiments disclosed and described herein;

[0016] FIGS. 4A - 4E graphically illustrate DSC and TMA analysis of cordierite bulk glass and glass frits according to one or more embodiments disclosed and described herein;

[0017] FIG. 5 graphically illustrates in-situ XRD/Rietveld qualification cordierite bulk glass according to embodiments disclosed and described herein

[0018] FIGS. 6A and 6B are SEM images of cordierite glass bulk and glass frit according to one or more embodiments is closed and described herein;

[0019] FIGS. 7A - 7D are SEM images of cordierite glass frit according to one or more embodiments disclosed and described herein;

[0020] FIGS. 8A - 8D graphically illustrate DSC and TMA analysis of lithium aluminum silicate bulk glass and glass frit according to one or more embodiments disclosed and described herein;

[0021] FIGS. 9 A - 9D are SEM and Cu elemental images of lithium aluminum silicate glass frit according to one or more embodiments disclosed and described herein;

[0022] FIGS. 10A and 10B are SEM images of lithium aluminum silicate glass frit according to one or more embodiments disclosed and described herein;

[0023] FIGS. 11A and 11B are SEM images of lithium aluminum silicate glass frit according to one or more embodiments disclosed and described herein; [0024] FIGS. 12A - 12D are SEM and Cu elemental images of lithium aluminum silicate glass frit according to one or more embodiments disclosed and described herein;

[0025] FIG. 13 is an SEM of a Yoshiokaite glass ceramic according to one or more embodiments disclosed and described herein;

[0026] FIGS. 14A and 14B graphically illustrate DSC and TMA analysis of calcium aluminum silicate frit according to one or more embodiments disclosed and described herein;

[0027] FIGS. 15A and 15B are SEM and Cu elemental images of calcium aluminum silicate frit according to one or more embodiments disclosed and described herein;

[0028] FIGS. 16A - 161 are SEM images, EDX spectra, and Cu elemental images of calcium aluminum silicate frit according to one or more embodiments disclosed and described herein;

[0029] FIGS. 17A - 17C graphically illustrate x-ray diffraction results of calcium aluminum silicate frit according to one or more embodiments disclosed and described herein;

[0030] FIG. 18 is SEM images of lithium silicate glasses decorated with Cu according to one or more embodiments disclosed and described herein; and

[0031] FIGS. 19A and 19B are SEM images of a polished cross section of lithium silicate according to one or more embodiments disclosed and described herein.

DETAILED DESCRIPTION

[0032] Reference will now be made in detail to embodiments of glass ceramic composites having metal networks and methods for manufacturing glass ceramic composites. In some embodiments, a glass ceramic composite comprises a plurality of cells forming a glass ceramic microstructure and a ghost network surrounding and separating individual cells of the plurality of cells, wherein the ghost network is a discontinuity in the microstructure, and wherein metal decorates at least a portion of the ghost network. In one or more embodiments, a method for manufacturing a glass ceramic composite comprises: forming a glass powder comprising at least one oxide of a metal selected from Groups Vl-Xll of the periodic table into a green body of desired shape; ceramming the green body by firing the green body using a heating rate from greater than or equal to 100 °C/ hour to less than or equal to 350 °C/hour to a hold temperature from greater than or equal to 600 °C to less than or equal to 1200 °C and holding the green body at the hold temperature for a duration from greater than or equal to 1 hour to less than or equal to 20 hours. The glass ceramic composite comprises: a plurality of cells forming a glass ceramic microstructure and a ghost network surrounding and separating individual cells of the plurality of cells, wherein the ghost network is a discontinuity in the microstructure and wherein metal decorates at least a portion of the ghost network.

[0033] Glass ceramic composites having metal networks according to embodiments are engineered to have an additional phase in the glass ceramic composites that is metallic and, when formed with an adequate distribution, will provide improved electrical conductivity and thermal conductivity of the glass ceramic composite. In addition, a fine metal dispersion in the glass ceramic composite of embodiments is expected to toughen the glass ceramic.

[0034] The amount and distribution of the additional phase will, in embodiments, control the final physical properties of the glass ceramic composite. For instance, in some embodiments, it is possible to engineer properties in the bulk material of the glass ceramic composite or along/in the network of the frit particle contact surfaces that remain visible even after sintering and densification in many glass ceramics due to discontinuities in crystal structure or microstructure. The discontinuities can be observed using a scanning electron microscope (SEM). Therefore, even after the frit particles are sintered or cerammed and are no longer present in the glass ceramic article, a three dimensional (3D) network of discontinuities exist where the individual frit particles contacted one another before the sintering or ceramming. Without being bound by any particular theory, it is believed that these boundaries form due to segregation and exsolution processes during crystallization and ceramming, so that they form the 3D network of discontinuities, which is referred to herein as a "ghost network." The ghost network has similarities to a grain boundary network, but scales at the level of the frit particles used to form the green body before sintering or ceramming. Accordingly, in one or more embodiments, the glass ceramic composite includes a plurality of that form a glass ceramic micro structure. As used herein, "glass ceramic microstructure" means the arrangement of phases in the glass ceramic including the quantity, shape, and size of the phases, as well as the chemical composition of the glass ceramic. The cells exist limited by the ghost network such that the ghost network surrounds and separates individual cells and the sizes of the cells roughly approximate the size of the frit particles in the green body before they were sintered or cerammed. Accordingly, a ghost network can, for example, separate and surround, adjacent cells formed which have formed by crystallization and sintering in the ceram process from two frit particles. In embodiments comprising a sintered frit compact, the ghost networks constitute a 3D continuous network. In embodiments of glass ceramic composites, the ghost network is "filled" or "decorated" with a continuous film or discontinuous precipitates of the metal that was added as superaddition to the glass composition or formed from a superaddition precursor noble metal oxide or salt during the reducing ceram process. In other words, metal decorates at least a portion of the ghost network. As used herein, the phrase "metal decorates" or " metal decoration" means that a metal has been formed, filled, or otherwise disposed at location, for example in the ghost network. Thus, some new, engineered functionality of the bulk material (electric conductivity, ion conductivity, magnetic response, etc.) may be obtained.

[0035] With reference now to FIGS. 1A and I B, glass ceramic materials made from glass frit will be described. FIG. 1 A depicts glass frit particles 1 10 packed together, such as, for example, cold-pressed or green-compacted, before a sintering/densification step. As can be seen in the embodiments depicted in FIG. 1A, the glass powder or frit particles 1 10 are a powder and are physically packed together with open spaces 1 12 between the glass frit particles 1 10. Each glass frit particle 1 10 has a surface 1 1 1. Portions of the surfaces 1 1 1 of the glass frit particles 1 10 contact portions of surfaces 1 11 of one or more other neighboring glass frit particles 1 10. These packed glass frit particles 1 10 can then be formed into a dense glass ceramic by conducting a ceram cycle. [0036] For instance, the packed glass frit particles shown in FIG. 1A may be sintered or otherwise densified— such as by, for example, natural sintering or sintering under applied stress: uniaxial hot-pressing, isostatic hot pressing, or spark plasma sintering— to form the glass ceramic depicted in FIG. IB. As shown in FIG. IB, sintering of the packed glass frit particles 1 10 leads to shape changes of the frit particles, neck formation, neck enlargement, overall densification of the packed glass frit particles 1 10 to fill in the open spaces 112 (shown in FIG. 1A). The surfaces 111 of the glass frit particles 110 (shown in FIG. 1 A) sinter together during the ceram cycle forming a plurality of cells 110' from the frit particles and forming a ghost network 120, which separates and surrounds the individuals cells 110'. Even after the sintering/ceram cycle, the ghost networks still exist as discontinuities in the cerammed glass ceramic micro structure, separating the clusters of glass ceramic that were originally a frit particle and forming a three dimensional network with the typical cell dimension of the median frit particle diameter. If glass compositions do not contain any exsolutable components in their glass composition, such as, for example, the oxide of a metal or its precursor that reduces to insoluble metal or, for example, small amounts of mobile precursors of an insoluble oxide, carbide, nitride, alloy or the like that forms into either glass or crystalline phase of the glass ceramic, then the chemical discontinuity at the ghost networks can be small and only consists of minor segregation. In the extreme case of presence of noble metal precursors in the glass composition and realization of the ceram cycle under reducing environment, the noble metal will be exsoluted during the crystallization of the glass and will preferentially locate in the ghost networks. In this case, the ghost network chemistry will be very different from the bulk glass ceramic in the frit particles, showing a new metallic phase. The amount of that metal depends on its solubility in the glass the possible superaddition of one or more metal precursors in the glass. Its distribution depends on the glass composition and the ceram cycle and the reducing environment.

[0037] FIGS. 2A - 2C show a similar effect of ceramming glass frit particles as shown in FIGS. 1A and IB, but the embodiments shown in FIGS. 2A - 2C include coating the glass frit particles with a thin layer of metal or metal-forming precursor component 21 1, so that the powder compact transforms again in a reducing ceram cycle under sintering and crystallization into a glass ceramic with a metal network 220. For instance, as shown in the embodiments of FIG. 2A the metal-containing component 211, which may be, for example, a copper salt or mixture of copper and other transition metal salts, is present at the surfaces of the glass frit particles 210. Initially, before the sintering/densification step, the glass frit particles 210 are a glass powder and open spaces 212 are present between the glass frit particles 210. Although, FIG. 2A shows the metal-containing component 21 1 covering the entire surface of powdered glass frit particles 210, it should be understood that in some embodiments, the metal-containing component 211 may only cover a portion of the surface of one or more glass frit particles 210. In one or more embodiments, the metal-containing component 211 is selected to be one or more metal-containing components, such as, for example metal oxides, that can easily be reduced by conducting a sintering/densification step under a reducing atmosphere, such as, for example an atmosphere comprising low oxygen partial pressure, argon, nitrogen, hydrogen, CO, CO₂ or mixtures thereof, carbon/CO, H2/H₂O or solid state buffers, such as, for example, AI/AI₂O3, etc. Thereby, the easily reducible metal-containing component is reduced to a metal, remains in its original location in the ghost network and produces a decoration of the ghost network.

[0038] FIG. 2B illustrates the resulting glass ceramic composite after ceramming. Adequate ceram cycles enable crystallization of the glass, sintering of the powder particles, and reduction of the metal precursor to metal. In this configuration, the metal-precursor coated glass frit particles 210 transform into a dense glass ceramic having a plurality of cells 210', a ghost newtwork is formed (not shown) which separates and surrounds the individuals cells 210', and the frit particle coating transforms into a metal network 220 at the ghost networks. In the embodiment of FIG. 2B, the metal network 220 decorates the entire ghost network so the ghost network and metal network 220 are located at the same position. In other embodiments, the metal network 220 may only decorate a portion (or less than the entirety) of the ghost network. Embodiments of the glass ceramic composite shown in FIG. 2B is formed by ceramming— including sintering/densifying— the structure shown in FIG. 2 A. As shown in the embodiments illustrated in FIG. 2B, after a successful ceram cycle, the glass frit particles 210 are sintered together into a dense body under filling the open spaces 212 (shown in FIG. 2A) to form cells 210'. After the sintering process is complete, the glass ceramic composite reaches almost full density. For instance, in embodiments, the residual porosity of the glass ceramic after the ceram process is less than or equal to 5%, such as less than or equal to 4%, less than or equal to 3%, less than or equal to 2%, or less than or equal to 1%. During the ceram cycle, crystallization of the glass particles takes place under formation of crystalline phases and formation of the final glass ceramic.

[0039] As shown in the embodiments depicted in FIG. 2B, the glass ceramic preserves the ghost networks in the sintering and crystallization process. In this configuration, the metal oxide or metal precursor coating layer on the glass particles is reduced to a metal during the ceramming process and forms a metal network 220 along the ghost networks in the resulting glass ceramic. The presence of metal in the bulk of the glass, at the ghost network illustrated in FIGS. 2B and 2C is also referred to herein as "metal decoration" or "metal decorating." As illustrated in FIG. 2C, after ceramming in a reducing environment a metal network 220 is obtained that can also fill triple points and glass particle interstices, resulting into a glass ceramic, where the cells 210' maintain a shape and dimensions similar to the shape and dimensions of the glass frit powder particles 210 shown in FIG. 2A even after the sintering/densification process. The metal network, according to embodiments, is positioned within the ghost networks and is in physical contact with the ceramic network. In configuration 2C, metal film width are much larger than in configurations 2B and IB

[0040] In some embodiments, the metal network 220 is present substantially at the ghost network, such as, for example, at least 80% of the metal in the glass ceramic composite is present at the ghost network, such as at least 90% of the metal in the glass ceramic composite is present at the ghost network, at least 95% of the metal in the glass ceramic composite is present at the ghost network, at least 98% of the metal in the glass ceramic composite is present at the ghost network, at least 99% of the metal in the glass ceramic composite is present at the ghost network.

[0041] Small metal precipitates and metal films are also able to, in embodiments, interact with propagating cracks and stop crack propagation by plastic deformation, thus increasing the toughness of the glass ceramic compared to a glass ceramic without metal dispersion. However, small metal particle dispersions are not expected to alter (degrade) the hardness of the glass ceramic.

[0042] In embodiments, metal decoration can be present at the ghost networks forming a discontinuous or continuous three dimensional metal network along the ghost network. As referred to herein, a continuous three dimensional metal network indicates that the interconnectivity of all copper is perfect (referred to as an interconnectivity of 1). With a continuous three dimensional metal network all ghost networks are covered by a copper film that is present along all ghost networks. A discontinuous three dimensional metal network, as referred to herein does not have perfect interconnectivity (interconnectivity is less than 1). If there is no interconnectivity (interconnectivity is 0), there may be individual copper particles in the ghost networks, but they are not interconnected. A discontinuous three dimensional metal network may have an interconnectivity between 0 and less than 1, where a fraction of the copper particles is interconnected. It is desirable to have the highest possible interconnectivity. Since upon ceramming, a frit particle of the green body transforms into cerammed material cell having the size of the initial frit particle and is limited by the surrounding ghost networks, the cell size of the three dimensional metal network is determined by the median frit particle size, and the regularity of the three dimensional metal network is determined by the frit particle size distribution. Thus, the cell size may be measured in the same manner as the dso, dio, and dc>o, etc. of the frit particles used to form the glass ceramic material. Metal ghost networks can be engineered with cell sizes ranging from greater than or equal to 1 μm to less than or equal to 100 μm, such as from greater than or equal to 5 μm to less than or equal to 95 μm, from greater than or equal to 10 μm to less than or equal to 90 μm, from greater than or equal to 15 μm to less than or equal to 85 μm, from greater than or equal to 20 μm to less than or equal to 80 μm, from greater than or equal to 25 μm to less than or equal to 75 μm, from greater than or equal to 30 μm to less than or equal to 70 μm, from greater than or equal to 35 μm to less than or equal to 65 μm, from greater than or equal to 40 μm to less than or equal to 60 μm, or from greater than or equal to 45 μm to less than or equal to 55 μm. In other embodiments, the cell sizes range from greater than or equal to 10 μm to less than or equal to 50 μηι, such as from greater than or equal to 15 μηι to less than or equal to 45 μηι, greater than or equal to 20 μηι to less than or equal to 40 μηι, or greater than or equal to 25 μηι to less than or equal to 35 μηι. The dispersion of the cell size depends on the breadth of the particle size distribution of the used glass powder.

[0043] In the reducing ceram/sintering process, metal precursors will be reduced to metal and form at locations that are most favorable from a point of view of an energy balance. The energy balance is often more favorable at intersections of ghost networks, referred to herein as "triple points," and when the metals form in the ghost network, the metal may first form at the triple points. For low metal concentrations, only triple points may be decorated and not all the ghost networks will be decorated, creating a discontinuous three dimensional metal network. In such embodiments, metal can form at the triple points of the frit particle packing, forming small individual precipitates throughout the resulting material, which lack interconnectivity, would not contribute to good metallic conductivity, but would contribute to the toughening of the material.

[0044] As mentioned above, the geometry of the ghost network is primarily determined by the shape and dimensions of the glass frit particles. Although the shape of the glass frit particles evolves during crystallization and sintering/densification, there is a correlation between the shape and dimensions of the glass frit particles in the initial green powder packing before ceramming and the shape and dimensions of the cerammed particles after sintering/densification/crystallization. Therefore, in embodiments, the ghost network cellular structure in the glass ceramic can be controlled by the median particle size and particle size distribution of the initial green glass powder. It should be understood that the median particle size and particle size distribution ranges— as well as other ranges recited in this disclosure— include all numerical values encompassed by the recited ranges as though they were each listed individually.

[0045] In some embodiments, the frit contains fine glass particles having a median particle size from greater than or equal to 5 μηι to less than or equal to 15 μηι, such as from greater than or equal to 6 μηι to less than or equal to 14 μηι, from greater than or equal to 7 μm to less than or equal to 13 μm, from greater than or equal to 8 μm to less than or equal to 12 μm, or from greater than or equal to 9 μm to less than or equal to 11 μm. In other embodiments, the median particle size of the fine glass frit is from greater than or equal to 7 μm to less than or equal to 10 μm, such as from greater than or equal to 8 μm to less than or equal to 9 μm. In one or more embodiments, the fine glass frit particles have a dio particle size distribution less than or equal to 3.0 μm, such as less than or equal to 2.5 μm, less than or equal to 2.0 μm, less than or equal to 1.5 μm, less than or equal to 1.0 μm or less than or equal to 0.5 μm. According to embodiments disclosed and described herein, dio is defined as the particle diameter at which 10% of the sample's volume is comprised of particles with a diameter less than this dio value. In one or more embodiments, the fine glass frit particles have a d₉₀ particle size distribution from greater than or equal to 10 μm to less than or equal to 30 μm, such as from greater than or equal to 12 μm to less than or equal to 28 μm, from greater than or equal to 14 μm to less than or equal to 26 μm, from greater than or equal to 16 μm to less than or equal to 24 μm, from greater than or equal to 18 μm to less than or equal to 22 μm, or about 20 μm. According to embodiments disclosed and described herein, dc>o is defined as the particle diameter at which 90% of the sample's volume is comprised of particles with a diameter less than this d₉₀ value. The particle sizes may be measure, for example, by conventional laser measurement techniques.

[0046] In some embodiments, frits contain coarse glass particles, having a median particle size from greater than or equal to 10 μm to less than or equal to 20 μm, such as from greater than or equal to 1 1 μm to less than or equal to 19 μm, from greater than or equal to 12 μm to less than or equal to 18 μm, from greater than or equal to 13 μm to less than or equal to 17 μm, or from greater than or equal to 14 μm to less than or equal to 6 μm. In other embodiments, the median particle size of the coarse glass frit is from greater than or equal to 12 μm to less than or equal to 16 μm, such as from greater than or equal to 13 μm to less than or equal to 15 μm. In one or more embodiments, the coarse glass frit particles have a dio particle size distribution from greater than or equal to 6 μm to less than or equal to 12 μm, such as from greater than or equal to 8 μm to less than or equal to 10 μm. In one or more embodiments, the coarse glass frit particles have a dw particle size distribution from greater than or equal to 10 μm to less than or equal to 30 μm, such as from greater than or equal to 12 μm to less than or equal to 28 μm, from greater than or equal to 14 μm to less than or equal to 26 μm, from greater than or equal to 16 μm to less than or equal to 24 μm, from greater than or equal to 18 μm to less than or equal to 22 μm, or about 20 μm.

[0047] The glass frit may have any composition that is capable of forming a glass ceramic having a ghost network, and where the additional metal phase material is soluble in the glass composition. The metal decoration described above and illustrated in FIGS. 2A - 2C is demonstrated for several glass families in one or more embodiments; on the families of glass compositions include glasses that undergo easily bulk nucleation and crystallization, glasses that exclusively undergo surface nucleation and crystallization, and glass compositions with mixed behavior depending on the exact glass composition and ceram cycle. In some embodiments, the glass compositions are such that the onset of sintering and crystallization are in the same temperature range within 20 °C. If sintering occurs much earlier than crystallization, then the green powder compact will transform in the ceram cycle first into a dense glass and then that bulk glass will crystallize. This configuration can be found for glass compositions with high alkali content and low alumina content. This case is not interesting for this application, because it mimics ceramming of bulk glass.

[0048] Metal decoration may be present in embodiments where the levels of residual glass in the glass ceramic is from greater than or equal to 2 mass% to less than or equal to 20 mass%, such as from greater than or equal to 4 mass% to less than or equal to 18 mass%, from greater than or equal to 6 mass% to less than or equal to 16 mass%, from greater than or equal to 8 mass% to less than or equal to 14 mass%, or from greater than or equal to 10 mass% to less than or equal to 12 mass%. The mass% may be measure, for example, by X-ray diffraction (XRD) analysis.

[0049] In one or more embodiments the glass frit particles are comprised of a composition selected from the group consisting of alkali aluminum silicates, and alkaline earth aluminum silicates, mixed alkali alkaline earth aluminum silicates and their derivatives including rare earth metals. Glass compositions can include additional oxides that serve as softening elements that substitute the glass network formers and modifiers or just help to adjust melting temperature, refining of the glasses, etc. In some embodiments, the glass frit particles are comprised of a composition selected from the group consisting of magnesium aluminum silicate, lithium aluminum silicate, and calcium aluminum silicate.

[0050] In embodiments, the glass frit particles are comprised of a magnesium aluminum silicate glass that comprises from greater than or equal to 45.0 mass% to less than or equal to 57.0 mass% S1O₂, such as from greater than or equal to 50.0 mass% to less than or equal to 55.0 mass% S1O₂; from greater than or equal to 18.0 mass% to less than or equal to 30.0 mass% AI₂O₃, such as from greater than or equal to 20.0 mass% to less than or equal to 28.0 mass% AI₂O₃, or from greater than or equal to 20.0 mass% to less than or equal to 25.0 mass% AI₂O₃; from greater than or equal to 0.0 mass% to 2.0 mass% B₂O₃; such as from greater than 0.0 mass% to less than or equal to 1.5 mass% B₂O₃; from greater than or equal to 11.0 mass% to less than or equal to 23.0 mass% MgO, such as from greater than or equal to 13.0 mass% to less than or equal to 15 mass% MgO; from greater than or equal to 0.0 mass% to less than or equal to 7.0 mass% ZnO, such as from greater than 0.0 mass% to less than or equal to 6.5 mass% ZnO; from greater than or equal to 0.0 mass% to less than or equal to 4.0 mass% BaO, such as from greater than 0.0 mass% to less than or equal to 3.0 mass% BaO; from greater than or equal to 0.0 mass% T1O2 to less than or equal to 10.0 mass% T1O2, such as from greater than 0.0 mass% to less than or equal to 8.0 mass% T1O₂; and from greater than or equal to 0.0 mass% to less than or equal to 5.0 mass% CaO, such as from greater 0.0 mass% to less than or equal to 1.0 mass% CaO.

[0051] In some embodiments, the glass frit particles are comprised of a lithium aluminum silicate glass that comprises from greater than or equal to 75.0 mass% to less than or equal to 85.0 mass% S1O₂, such as from greater than or equal to 80.0 mass% to less than or equal to 83.0 mass% S1O2; from greater than or equal to 2.0 mass% to less than or equal to 6.0 mass% AI₂O₃, such as from greater than or equal to 3.0 mass% to less than or equal to 5.0 mass% AI₂O₃; from greater than or equal to 1.0 mass% to less than or equal to 3.0 mass% MgO, such as from greater than or equal to 1.5 mass% to less than or equal to 2.5 mass% MgO; from greater than or equal to 8.0 mass% to less than or equal to 12.0 mass% Li₂0, such as from greater than 9.0 mass% to less than or equal to 11.0 mass% Li₂0; from greater than or equal to 0.0 mass% to less than or equal to 4.0 mass% P₂O₅, such as from greater than 0.0 mass% to less than or equal to 3.0 mass% P₂O₅.

[0052] In some embodiments, the glass frit particles are comprised of a calcium aluminum silicate glass that comprises from greater than or equal to 20.0 mass% to less than or equal to 30.0 mass% S1O₂, such as from greater than or equal to 25.0 mass% to less than or equal to 28.0 mass% S1O₂; from greater than or equal to 40.0 mass% to less than or equal to 50.0 mass% AI₂O₃, such as from greater than or equal to 43.0 mass% to less than or equal to 47.0 mass% AI₂O₃; and from greater than or equal to 20.0 mass% to less than or equal to 30.0 mass% CaO, such as from greater than or equal to 25.0 mass% to less than or equal to 28.0 mass% CaO.

[0053] In addition to the glass compositions discussed above, to form the metal network within the glass ceramic, a metal-containing component is added to any of the glass compositions disclosed herein. The metal-containing component may be any suitable metal-containing precursor, such as metal oxides. In some embodiments the metal-containing component comprises at least one oxide of metal of Groups Vl-Xll of the periodic table. In one or more embodiments, the metal-containing component comprises at least one oxide of a metal of Group IX- XII of the periodic table. In embodiments, the metal-containing component is at least one oxide of a metal oxide selected from the group consisting of copper, zinc, silver, cobalt, nickel, tin, and mixtures thereof.

[0054] In the embodiments disclosed herein, the metal-containing component is added to the glass forming raw materials before mixing and melting— such as those listed in the preceding paragraphs— as a superaddition. As used herein, the term "superaddition" is defined as a component that is added to the composition in addition to 100% of the glass components. Accordingly, a superaddition of 3 mass% CuO, for example, means that 3 mass% of CuO is added to 100 mass% of the glass components (i.e., if the mass of the glass components equals 100 kg, a 3 mass% superaddition of CuO would add 3 kg of CuO for a total of 103 kg). In one or more embodiments, the metal-containing component is added as a superaddition to the glass components in amounts from greater than or equal to 5.0 mass% to less than or equal to 80.0 mass%, such as from greater than or equal to 10.0 mass% to less than or equal to 75.0 mass%, from greater than or equal to 15.0 mass% to less than or equal to 70.0 mass%, from greater than or equal to 20.0 mass% to less than or equal to 65.0 mass%, from greater than or equal to 25.0 mass% to less than or equal to 60.0 mass%, from greater than or equal to 30.0 mass% to less than or equal to 55.0 mass%, or from greater than or equal to 35.0 mass% to less than or equal to 50.0 mass%. In other embodiments, the metal- containing component is added as a superaddition to the glass components in amounts from greater than or equal to 5.0 mass% to less than or equal to 25.0 mass%, such as from greater than or equal to 10.0 mass% to less than or equal to 20.0 mass%, from greater than or equal to 12.5 mass% to less than or equal to 18.5 mass%, or from greater than or equal to 15.0 mass% to less than or equal to 17.0 mass.

[0055] Providing metal decoration in the glass ceramic composite will, in embodiments, allow one to tune electrical conductivity, thermal conductivity, thermal expansion and mechanical properties— such as toughness and thermal shock resistance— of the glass ceramic composite.

[0056] Manufacturing glass ceramics is more complex when starting from a glass powder than a glass melt. Manufacturing glass ceramics from glass powders requires not only melting and milling the glass into powder, but also pre-forming a shaped green body of the powder and densifying and crystallizing it. Accordingly, in one or more embodiments, successful processing of glass ceramics from a frit requires an engineered ceram cycle with tuned sintering and crystallization. For example, in embodiments, if the sintering step occurs much earlier than the crystallization step, then the behavior is close to the traditional ceramming of a dense bulk glass, which may be undesirable in embodiments, because no ghost network forms or only a very weak imprint of such ghost networks will appear with very small chemical discontinuity due to rapid diffusion and sintering. However, in other embodiments, if the crystallization step occurs much earlier than the sintering step, then the crystallized body may not sinter to full density and may remain porous. Accordingly, in one or more embodiments, sintering and crystallization occur in the same temperature window to allow successful ceramming of frit-based articles.

[0057] Compacted pellets of reactive glass frit can be used to produce glass- ceramic composites in a complex ceram cycle that combines crystallization, densification, and reduction. The resulting glass ceramic contains reaction products of the reduction distributed either homogeneously across the entire bulk glass ceramic, along grain boundaries of the glass ceramic (between glass and the formed crystals) or along the ghost networks. In embodiments, the reduction reaction is initiated by conducting a ceram cycle in a reducing atmosphere, such as, for example, an atmosphere comprising low oxygen partial pressure, argon, nitrogen, hydrogen, carbon monoxide, carbon dioxide, or mixtures thereof. In some embodiments, the copper-containing precursor that is added as a superaddition in the glass forms metallic copper in the reductive ceram cycle. This metallic copper can be exsoluted from the crystallizing glass ceramic and could form within a former frit particle either in the remaining glass, at interfaces between glass and new-formed crystal, or at the ghost network. If the densification is not fully completed, formation of metallic copper is the most favorable at the ghost networks (minimum in stress strain energy and surface energies). Thus, metallic copper forms preferentially in the ghost networks during the reductive ceram process forming a continuous or semi-continuous metal film along the ghost networks. This metal formation along the ghost networks can create a copper continuous conductive network if the copper quantity is sufficient and the interconnectivity of copper is good. The interdistance of the copper lines in the continuous conductive network is determined by the frit particle size and its regularity is determined by the frit particle size distribution. Although the above reduction is described using copper as the exemplary metal, it should be understood that the same process may be conducted with other metal-containing components, such as, for example, oxides of silver, zinc, nickel, cobalt and tin or other noble transition or heavy metals.

[0058] In one or more embodiments, a glass melt is prepared by melting the raw glass materials and the additional metal phased component into a homogeneous melt. In some embodiments, the melt may be formed into glass pellets by pouring the melt into a cold, small frame. In some embodiments, the small bulk glass pallets may be post-annealed for relaxation of residual stresses. In other embodiments, the glass may be formed into a glass frit by pouring the melt into water, so that glass shards may be obtained. These glass shards may be milled to be either coarse frit or fine frit, as described hereinabove. For instance, in some embodiments, to form coarse glass frit the glass shards may be ball-milled for a duration of from greater than or equal to 6 hours to less than or equal to 10 hours, such as about 8 hours and then sieved through an appropriate sieve. In other embodiments, to form fine frit, the coarse frit is additionally attrition milled at a rate from greater than or equal to 8000 turns/min to less than or equal to 12000 turns/min, such as about 10000 turns/min for a duration from greater than or equal to 6 hours to less than or equal to 10 hours, such as about 8 hours. After the attrition milling, the frit may be sieved in an appropriate sieve for the fine frit.

[0059] To prepare for the ceram cycle of bulk glasses, in embodiments, the glass pellets formed as described above were cut into slices and polished. Similarly, in embodiments, the frits (glass powders) formed as described above were cold- pressed under pressures from greater than or equal to 0.5 bar to less than or equal to 2.0 bar, such as from greater than or equal to 0.5 bar to less than or equal to 1.5 bar, or about 1.0 bar. This pressing of the glass frit forms pellets having diameters from greater than or equal to 2 mm to less than or equal to 40 mm, such as from greater than or equal to 3 mm to less than or equal to 35 mm, from greater than or equal to 5 mm to less than or equal to 30 mm, from greater than or equal to 7 mm to less than or equal to 25 mm, from greater than or equal to 10 mm to less than or equal to 20 mm, or from greater than or equal to 12 mm to less than or equal to 18 mm. The glass frit pellets have, in embodiments, a thickness from greater than or equal to 1 mm to less than or equal to 7 mm, such as from greater than or equal to 2 mm to less than or equal to 5 mm, or from greater than or equal to 3 mm to less than or equal to 4 mm. It should be understood that, according to one or more embodiments, the pellets may have dimensions different than those disclosed above.

[0060] Although the ceram process will vary depending on the composition being treated, in embodiments, the ceram process are conducted in a reducing atmosphere comprising argon, nitrogen, hydrogen, and mixtures thereof or a carbon envelop and argon gas. The duration of the ceram process may, in some embodiments, be from greater than or equal to 1 hour to less than or equal to 24 hours, such as from greater than or equal to 2 hour to less than or equal to 22 hours, from greater than or equal to 3 hour to less than or equal to 20 hours, from greater than or equal to 4 hour to less than or equal to 18 hours, from greater than or equal to 6 hour to less than or equal to 16 hours, from greater than or equal to 7 hour to less than or equal to 14 hours, from greater than or equal to 8 hour to less than or equal to 12 hours, or from greater than or equal to 9 hour to less than or equal to 11 hours. The temperature of the ceram process is from greater than or equal to 600 °C to less than or equal to 1200 °C, such as from greater than or equal to 650 °C to less than or equal to 1150 °C, from greater than or equal to 700 °C to less than or equal to 1100 °C, from greater than or equal to 750 °C to less than or equal to 1050 °C, from greater than or equal to 800 °C to less than or equal to 1000 °C, or from greater than or equal to 850 °C to less than or equal to 950 °C.

[0061] According to embodiments, during the ceram process, the reduction of copper oxide contained in the glass composition of the glass frit occurs for most glass compositions before the glass frit sinters to full density. If sintering occurs before reduction, then a simple reduction of a copper oxide containing bulk glass is obtained, and ghost networks do not exist once the reduction occurs. Such frits can only produce fine copper metallic dispersions in the bulk glass, but they do not produce ghost network decoration by metallic copper. Typical examples of the latter case are alkali glasses with high alkali level and low copper level.

[0062] Glass ceramic composites according to embodiments disclosed herein have a ghost network decorated with metal that can increase the electric conductivity of the glass ceramic beyond the electric conductivity that can be realized in glass ceramics that do not have ghost networks decorated with metals. Similarly, glass ceramic composites according to embodiments disclosed or described herein have thermal conductivity, thermal expansion, hardness, and other thermal and mechanical properties that are equal to or greater than the same properties in glass ceramics having the same composition but do not have ghost networks decorated with metal. [0063] Ceramic glass composites as disclosed and described in embodiments herein may be used in many different applications. For example, evolving technology drives a need for glass, glass-ceramic, or ceramic substrate materials that contain a large number of conductive paths in an insulating material that allow manufacture of substrate plates with conductive paths between the two plate surfaces. Ceramic substrates are preferred over substrates of other materials for reasons including, but not limited to, the fact that ceramics are chemically inert and can be tuned to have high strength and toughness. Further, glass ceramics can be formed into substrates using a number of processes, such as, for example, rolling, pulling, and drawing. In addition, glass ceramics typically have improved mechanical properties compared to glass. In some embodiments, glass ceramics can be tuned to have very low thermal expansion and are suited to operate well through temperature changes.

[0064] In addition to the above, embodiments where the glass ceramics are made from frit, processes such as, for example, rolling, pressing, molding, additive manufacturing, casting, tape casting, and printing allow the glass ceramic to be formed into complex shapes.

[0065] The conductive glass ceramic composites disclosed and described herein can be used for power switching in electronic and non-electronic applications, and in touch applications. Additional uses of glass ceramic composites disclosed and described herein include use as electronic circuit boards, such as by acting as the conductive through-board via. In some embodiments, an electronic device, comprises: electrical components; and a glass ceramic composite component electrically connected to the electrical components. The glass ceramic composite comprises: a plurality of cells defined by a ghost network in the crystalline structure, wherein metal decorates at least a portion of the ghost network.

[0066] A first clause includes a glass ceramic composite comprising: a plurality of cells forming a glass ceramic microstructure and a ghost network surrounding and separating individual cells of the plurality of cells, wherein the ghost network is a discontinuity in the microstructure, and wherein metal decorates at least a portion of the ghost network. [0067] A second clause includes the glass ceramic composite of the first clause, wherein a porosity of the glass ceramic composite is less than or equal to 5%.

[0068] A third clause included the glass ceramic composite of any one of the first and second clauses, wherein the metal that decorates at least a portion of the ghost network comprises at least one metal of Groups Vl-Xll of the periodic table.

[0069] A fourth clause includes the glass ceramic composite of any one of the first through third clauses, wherein the metal that decorates at least a portion of the ghost network comprises at least one metal of Group 1X-X11 of the periodic table.

[0070] A fifth clause includes the glass ceramic composite of any one of the first through fourth clauses, wherein the metal that decorates at least a portion of the ghost network comprises a metal selected from the group consisting of copper, nickel, silver, zinc, tin, cobalt, and mixtures thereof.

[0071] A sixth clause includes the glass ceramic composite of any one of the first through fifth clauses, wherein at least 95% of all metals present in the glass ceramic composite are located in the ghost network.

[0072] A seventh clause includes the glass ceramic composite of any one of the first through sixth clauses, wherein the glass ceramic composite comprises Yoshiokaite as a crystalline phase.

[0073] An eighth clause includes the glass ceramic composite of any one of the first through seventh clauses, wherein the glass ceramic composite comprises Cordierite as a crystalline phase.

[0074] A ninth clause includes the glass ceramic composite of any one of the first through eighth clauses, wherein the glass ceramic composite comprises at least one of lithium meta silicate, lithium disilicate, and beta-quartz as a crystalline phase.

[0075] A tenth clause includes the glass ceramic composite of any one of the first through ninth clauses, wherein the metal that decorates at least a portion of the ghost network forms a continuous metal network. [0076] An eleventh clause includes the glass ceramic composite of any one of the first through tenth clauses, wherein the metal that decorates at least a portion of the ghost network forms a discontinuous metal network.

[0077] A twelfth clause includes the glass ceramic composite of any one of the first through eleventh clauses, wherein the plurality of cells have a size greater than or equal to 1 μm to less than or equal to 100 μm.

[0078] A thirteenth clause includes the glass ceramic composite of any one of the first through twelfth clauses, wherein the plurality of cells have a size greater than or equal to 10 μm to less than or equal to 50 μm.

[0079] A fourteenth clause includes the glass ceramic composite of any one of the first through thirteenth clauses, wherein the glass ceramic composite comprises residual glass in amounts from greater than or equal to 2 mass% to less than or equal to 30 mass%.

[0080] A fifteenth clause includes the glass ceramic composite of any one of the first through fourteenth clauses, further comprising a first surface and an opposing second surface, wherein the ghost network provides at least one conductive pathway from the first surface to the second surface.

[0081] A sixteenth clause includes the glass ceramic composite of any one of the first through fifteenth clauses, wherein a conductive pathway is electrically conductive.

[0082] A seventeenth clause includes the glass ceramic composite of any one of the first through sixteenth clauses, wherein the discontinuity in the micro structure comprises a difference in a quantity, shape, or size of crystalline phases of the glass ceramic micro structure.

[0083] An eighteenth clause includes the glass ceramic composite of any one of the first through seventeenth clauses, wherein the discontinuity in the micro structure comprises a difference in a chemical composition of the glass ceramic microstructure. [0084] A nineteenth clause includes a method for manufacturing a glass ceramic composite comprising: forming a glass powder comprising at least one metal selected from Groups Vl-Xll of the periodic table into a green body of desired shape; ceramming the green body by firing the green body using a heating rate from greater than or equal to 100 °C/ hour to less than or equal to 350 °C/hour to a hold temperature from greater than or equal to 600 °C to less than or equal to 1200 °C and holding the green body at the hold temperature for a duration from greater than or equal to 1 hour to less than or equal to 20 hours, wherein the glass ceramic composite comprises: a plurality of cells forming a glass ceramic micro structure and a ghost network surrounding and separating individual cells of the plurality of cells, wherein the ghost network is a discontinuity in the micro structure, and wherein metal decorates at least a portion of the ghost network.

[0085] A twentieth clause includes the method of the nineteenth clause, wherein a porosity of the glass ceramic composite is less than or equal to 5%.

[0086] A twenty first clause includes the method of any of the ninteenth and twentieth clauses, wherein the at least one metal comprises at least one metal selected from Group 1X-X11 of the periodic table.

[0087] A twenty second clause includes the method of any of the ninteenth to twenty first clauses, wherein the at least one metal is selected from the group consisting of copper, nickel, silver, zinc, tin, cobalt, and mixtures thereof.

[0088] A twenty third clause includes the method of any of the ninteenth to twenty second clauses, wherein the at least one metal is batched as superaddition to a glass composition in an amount from greater than or equal to 5 mass% to less than or equal to 80 mass%.

[0089] A twenty fourth clause includes the method of any of the ninteenth to twenty third clauses, wherein the ceramming is conducted in a reducing atmosphere comprising oxygen at low partial pressure, argon, nitrogen, hydrogen, carbon monoxide, carbon dioxide and mixtures thereof. [0090] A twenty fifth clause includes the method of any of the ninteenth to twenty fourth clauses, wherein the ceramming is conducted in a reducing atmosphere comprising from greater than or equal to 2.0 vol% to less than or equal to 5.0 vol% H₂ and a remainder being argon.

[0091] A twenty sixth clause includes the method of any of the ninteenth to twenty fifth clauses, wherein the glass powder has a median particle size from greater than or equal to 5 μm to less than or equal to 50 μm, a dio particle size distribution less than or equal to 3.0 μm, and a d₉₀ particle size distribution from greater than or equal to 10 μm to less than or equal to 100 μm.

[0092] A twenty seventh clause includes the method of any of the ninteenth to twenty sixth clauses, wherein the glass powder has a median particle size from greater than or equal to 10 μm to less than or equal to 30 μm, a dio particle size distribution from greater than or equal to 6 μm to less than or equal to 12 μm, and a d₉₀ particle size distribution from greater than or equal to 10 μm to less than or equal to 80 μm.

[0093] A twenty eighth clause includes an electronic device, comprising: electrical components; and a glass ceramic composite component of any one of the first through eighteenth clauses electrically connected to the electrical components.

EXAMPLES

[0094] Embodiments will be further clarified by the following examples.

PREPARING GLASS FOR EXAMPLES 1 - 3

[0095] Glass compositions that were used in the following examples are described below.

[0096] For the examples used herein, Magnesium-aluminum-silicate, Li- aluminum silicate, and Ca-aluminum silicate glass compositions were used, and copper oxide was added at different levels as a superaddition. The three families of glasses that were chosen to demonstrate the general applicability of the forming a metal network in a glass ceramic composite. The examples include glasses that undergo only surface nucleation and no bulk nucleation (i.e., calcium aluminum silicates (CASOl, CAS02, CAS03, CAS04)), glasses that show bulk nucleation (i.e., lithium aluminum silicates containing phosphorous as nucleation agent, (L1S01 - L1S04)) and glasses that, depending on the ceram cycle, show or do not show bulk nucleation besides surface nucleation (i.e., cordierite glasses (CORD)). The chosen examples cover glass frits with early onset of crystallization compared to the onset of sintering (L1S01 -L1S04) and frits with similar onset temperatures for crystallization and sintering (CASOl, CAS 02, CAS03, CAS04). The examples also include cases where partial melting occurs before the onset of sintering of the frit (LlS01 -LlS04).

[0097] All glass compositions used in the examples were able to contain substantial level of copper oxide and could be formed into homogeneous glasses. It shall be noted that the compositions are given in mass%. All glass compositions used in the examples can contain copper oxide in their glass composition and, in reducing environment, undergo reduction and exsolute metallic copper. The glass compositions used in the following examples are provided in Tables 1 - 3 below.

[0098] Table 1 - Cordierite Glass Ceramics in wt% and mol% with CuO as superaddition and in mol % normalized on 100%.

[0099] Table 1 - continued

[00100] Table 1 - continued

[00101] Table 1 - continued

[00102] Table 2 - Lithium Aluminum Silicate Glass compositions in wt% and in mol% and with CuO as superaddition and in mol % normalized on 100%.

[00103] Table 2— continued

[00104] Table 3 - Calcium Aluminum Silicate Glass compositions in wt% with CuO as superaddition and in mol % normalized on 100%.

[00105] Table 3 - continued

[00106] Table 3 - continued

[00107] Table 3 - continued

[00108] The bulk glass was prepared by melting the compositions provided in Tables 1 - 3 into a homogeneous melt and quenching the melt rapidly to form a glass. Raw materials were sand, calcined alumina, magnesia, lithium carbonate, aluminum meta phosphate, zinc oxide, boron anhydrate, barium carbonate, titania, calcium oxide, cobalt oxide, nickel oxide, tin oxide and CuO. About 1 kg of the raw material mixtures of the desired glass composition was weighed, mixed in a tubular mixer, filled into a silica or platinum crucible, introduced into a preheated furnace, heated to the desired temperature in 2 hours, held at that temperature for 6 hours, and, if necessary, slightly cooled before pouring the melt. The exact melting conditions for the compositions of Tables 1 - 3 are summarized in Tables 4 - 6 below.

[00109] Table 4 - Melting Processes For Cordierite Glass Ceramics

Table 5 - Melting Processes For Lithium Aluminum Silicate

Table 6 - Melting Processes For Calcium Aluminum Silicate Glass

[00112] For forming a pellet of bulk glass, the melt crucible with the melt was taken out of the hot furnace and poured directly (with help of tongs) from the Pt or silica crucible into a cooled metal square frame with bottom plate. In this frame, the melt cooled immediately and adopted the shape of the frame, forming a small square pellet, for example 4 cm x 6 cm x 3 cm in height. From the rapid cooling, the frit pellets contained high levels of internal stresses. The glass pellets were post-annealed for several hours at temperatures at about 100 °C below the glass transition temperature. The pellet quality was then checked under polarized light. The absence of stress contours under an optical microscope with a polarizing light typically showed that a stress-free glass or glass with low stress level was obtained.

[00113] For making frit, the melt was poured into water, so that glass shards were obtained. These glass shards were milled to two types of frit, coarse frit and fine frit. For making coarse frit, the shards were ball-milled in a medium scale ball mill with media for 8 hours and sieved through a 50 μm sieve. The fraction that passed through the 50 μm sieve was captured as coarse frit. For the preparation of the fine frit, the ball-milled and sieved powder was placed together with fine media into an attrition mill and milled at 10000 turns/min for 8 hours.

[00114] The resulting powder was passed through a 25 μm sieve. The powder that passed the sieve is the fine frit. Typically, a fine frit was characterized by a median particle size <10 μm often < 5 μm, dio < 1 μηι, and a coarse frit was characterized by a median diameter of > 10 μm, such as, for example, 13 - 15 μm, dio from 8 - 10 μm, and d₉₀ around 20 μm. The particle size distribution of the resulting powders was measured by a Microtrac S3500 laser diffractometer. Representative particle size distributions of four samples are shown in the graphs of FIGS. 3A - 3D. FIG. 3A is a graphical representation of the particle size distribution of a coarse frit formed from L1S01, and FIG. 3B is a graphical representation of the particle size distribution of an attrition-milled fine frit formed from L1S01. FIG. 3C is a graphical representation of the particle size distribution of a coarse frit formed from CORD03, and FIG. 3D is a graphical representation of the particle size distribution of a frit formed from CASOl .

[00115] Most of the prepared glass samples were transparent. The copper- free glass samples were typically colorless, while glass samples containing low copper-levels were tinted in blue-green with color levels increasing with the level of copper in the composition. For further processing, the glass pellets were cut into slices and polished. Frits were cold-pressed under 1 bar into pellets, a particular shape of a formed green body, having diameters from 5 mm to 30 mm and thicknesses from 2 mm to 5 mm.

[00116] The crystallization behavior of bulk glass, coarse frit and fine frit was studied by differential scanning calorimetry (DSC). Differential scanning calorimetry (DSC) is a thermal analysis which permits to measure the temperature difference between a sample and a reference sample with known thermal properties (standard). Under input of heat energy, the sample temperature varies differently compared a known reference sample, so that a temperature difference can be measured between the two samples. This temperature difference is measured by a thermocouple and can be transformed into a heat flow (W/g). We used DCS to measure endothermic and exothermic events, while heating our glass samples at 20 K/min to 30 K/min in a NETZSCH 4040 Cell DSC. Thermal events include glass transition, melting (endothermic), crystallization (exothermic), and phase transformations or reactions. Frequently weight loss of the sample was also monitored during heating (TGA-thermogravimetric analysis) on the same instrument, providing the corresponding weight loss for each thermal events.

[00117] Heating rates of 10 °C/min or 20 °C/min or 30 K/min were used. Densification/shrinkage of the cold-pressed frit pellets (5 mm diameter rods) was studied by thermomechanical analysis (TMA) in a temperature range from room temperature to 1000 °C. A Q400TMA thermomechanical analyzer (TMA) was used to measure changes in sample length, such as growth or shrinkage as a function of temperature, time and applied force. TMA can be used to characterize linear expansion, glass transitions, and softening points of materials by applying a constant force to a specimen while varying temperature. For expansion measurements, a sample is mounted on a stage with minimal spring-load. For our measurements of shrinkage as function of temperature, samples of 4 - 7 mm diameter and at least 10 mm length were mounted into the sample holder in a sample furnace and heated to the desired top temperature while measuring the displacement of the top side. Our equipment operated in air.

[00118] Bulk glass slices and pressed pellets of the frits with different particle sizes were then cerammed on alumina setters in an open tube furnaces in air or in a closed alumina tube furnace in a th/Ar atmosphere comprising from greater than or equal to 2.0 vol% to less than or equal to 5.0 vol% H₂, or in a closed graphite crucible in Ar gas. The furnace temperature was measured by a thermocouple located close to the sample in the furnace. Ceram annealing cycles were conducted at durations from 1 hour to 20 hours at temperatures from greater than or equal to 600 °C to less than or equal to 1200 °C in air or in an H₂/Ar atmosphere comprising from greater than or equal to 2.0 vol% to less than or equal to 5.0 vol% H₂ at a heating rate from greater than or equal to 100 °C/hour to less than or equal to 350 °C/ hour, such as from greater than or equal to 150 °C/hour to less than or equal to 300 °C/hour. Representative ceram cycles for glass compositions are provided in Tables 7 - 9 below.

[00119] Table 7 - Ceram Process For Cordierite Glass Ceramics

Table 8 - Ceram Process For Lithium Aluminum Silicate Glass

Table 9 - Ceram Process For Calcium Aluminum Silicate Glass

[00122] After ceramming, scanning electron microscopy (SEM) and x-ray diffraction (XRD) were performed. The phases present in the fired (partially or fully cerammed) parts were identified by X-ray diffraction (XRD). A Philips PW1830 diffractometer (Co Ka radiation) or a Philips X'Pert Pro were used for X-ray diffraction. Spectra were typically acquired from 20 to 100° (2Θ). Rietveld refinement was used for quantification of the (crystalline) phase contributions. It shall be mentioned that amorphous, liquid and glass phases are not easily visible in the spectra; they provide no narrow lines, but a broad hump. Thus contributions from glass, amorphous etc. can only be derived indirectly from the Rietveld analysis and an assumption of phase compositions of the crystalline phases. SEM observations were conducted on sample surfaces, fracture surfaces, and polished cross-sections. Density, mechanical stability and coloration of cerammed samples were roughly estimated without any precision measurements.

[00123] A Phenom table top instrument and Jeol and Gemini SEM were used for the characterization of samples. Standard scanning electron microscopy, SEM, characterization was conducted on fracture surfaces and polished cross sections. For the observation of polished sections, samples were embedded in epoxy, sliced and polished. Secondary and backscattered imaging allowed assessing topography and phase contrast. In our glass ceramics, the metallic copper phase appeared in backscattered mode as a particularly bright phase. Chemical composition of the different phases and elemental distributions were obtained from (qualitative) analysis and elemental mapping by energy dispersive X-ray spectroscopy on the SEM.

[00124] Samples turned red or brown under annealing in reducing environment and occasionally even showed a metallic copper tint. Phase analysis was conducted by X-ray diffraction on powdered samples and Rietveld quantification. SEM (Phenom and Jeol) analysis was conducted on surfaces, fracture surfaces, and polished cross sections. In addition to SEM analysis, energy dispersive x-ray analysis (EDX) was used to identify level of crystallization, phase distribution and other micro structure features.

EXAMPLE 1

[00125] Bulk glasses and pressed compacts of coarse frit or fine frit of compositions CORD from Table 1 were used for making cordierite glass ceramics using different ceram cycles. The goal was to decorate the ghost networks in pressed frit pellets with metallic copper, densify the pellet, crystallize the glass and achieve substantial conductivity along the copper ghost network.

[00126] The example of cordierite glass ceramics was chosen, because MgAl- silicate glasses undergo mixed surface and bulk crystallization, with ceram temperature, frit particle size and copper content determining the contributions of the two mechanisms. Thus compositions with predominant surface nucleation can be chosen for our goal. In addition, the glass composition can be tuned by addition of nucleation agents and glass fluxes so that sintering, crystallization and reduction all occur in a common temperature window. That window is located for Cu-free composition CORDO l around 950 °C and is shifted to lower temperature with increasing CuO-content in the original glass. Thus, that window is located around 850 °C for CORD04 with 5% CuO in the glass composition.

[00127] According to DSC and TMA analysis, crystallization and sintering start at similar temperatures for cordierite glasses CORDOl - CORD04 and frit pellets. It was shown that copper starts to precipitate in glasses in reducing environment at temperatures as low as 750 °C. Thus, these MgAl-silicate glasses support the engineering of a continuous copper decoration along the ghost networks in a reduction-ceram process.

[00128] FIG. 4A graphically depicts DSC data for MgAl-silicate bulk glasses having the compositions of CORDOl - CORD04, and FIG. 4B graphically depicts DSC data for MgAl-silicate frit glasses having the compositions of CORDOl - CORD04 during heating in air. Further, FIG. 4C graphically depicts DSC data for MgAl-silicate bulk glasses having the compositions of CORD05 - CORD08, and FIG. 4D graphically depicts DSC data for MgAl-silicate frit glasses having the compositions of CORD05 - CORD08 during heating in air. For both, the bulk glasses and the frits, crystallization is promoted in copper-doped systems. Copper oxide acts as a nucleation agent, similarly to many transition metals (such as, for example, T1O₂) and introduces more homogeneous nucleation that is visible in substantial narrower crystallization peaks for the Cu-containing material. DSC comparison also shows a much sharper peak for the crystallization together with a significant shift to lower temperatures for the frit glasses compared to the corresponding bulk glasses. This indicates a strong contribution of surface crystallization and its progress towards the bulk, which is visible as earlier and faster crystallization in frit compacts and even more in compacts of fine frit. For the frit compact, the main crystallization peak is preceded by a minor second crystallization peak that cannot be distinguished in DSC of bulk glasses and may be attributed to surface crystallization. [00129] Undoped frit compacts exhibit strong shrinkage due to sintering above 900 °C, as shown graphically in FIG. 4E, which is a TMA in air analysis of compositions CORDOl - CORD04. Frit pellets doped with 3% copper oxide show a 50 °C lower sintering onset. Coarse frits show about 16% shrinkage above 900 °C. Pure bulk glass shows only 1% length change from room temperature to 1000 °C, and Cu-containing bulk glasses show about 1.3% - 2% shrinkage in air due to Cu-oxide exsolution and migration to the bulk surface. Shrinkage (TMA values) in air is only indicative for the behavior in reducing environment. It is expected that the material is softening during the reduction.

[00130] Ceram conditions in air were also derived from in-situ XRD of frit powder during heating in air with Rietveld quantification of the phases. FIG. 5 graphically depicts an in-situ XRD/Rietveld quantification of the phases forming in a 3% Cu-doped cordierite-type frit during heating in air. As shown in FIG. 5, crystallization starts at 800 °C with the formation of μ-cordierite that transforms into indialite at higher temperatures. Indialite/cordierite is the main crystalline phase in the glass ceramic with about 30% residual glass. Minor levels of gahnite, enstatite, osumilite BaMg₂Al₆Si903o and β-quartz form in a later stage of the reaction, β-quartz is a transient phase; it disappears at 1150 °C. Cu is integrated in solid solutions of enstatite, indialite, gahnite, and also is present in the residual glass. The in-situ XRD results suggest that long ceram cycles at 900 °C could provide sufficient crystallization or short cycles at 950 - 1000 °C; DSC indicates need of 1000 °C to 1050 °C, depending on the Cu content. Compared to Cu-free cordierite frit; crystallization is shifted by more than 50 °C to lower temperature in the presence of 5 wt% copper, β-quartz-free glass ceramics can be obtained above 1150 °C.

[00131] Bulk glasses and pellets of coarse and fine frits were then exposed to various ceram cycles in air. A 2 hour ceram cycle at 950 °C produced minor crystallization in a bulk glass only (shown by XRD) with small levels of quartz, indialite, and osumilite (Bao.1Mg2Al4.2Si10.8O30); crystallization is more advanced in Cu-containing bulk glasses. SEM studies on cross sections showed that crystallization occurred mainly at the surface of the bulk glass. The thickness of the crystallized surface scale increased with the Cu-content in the glass, indicating that copper promotes not only bulk crystallization, but also surface crystallization. For Cu-free glass, the crystallized surface scale thickness is only 10-20 μm, while in presence of 5% copper the scale thickness on bulk glass is 700 μm and thus extends completely over individual frit particles of the coarse frit. Thus cordierite frits exhibit mainly surface crystallization at 950 °C.

[00132] At higher temperature, 1000 °C/20 hours, cerammization was observed in the bulk glasses, and only 20 - 30 wt% residual glass were detected by XRD. Crystalline cordierite/indialite had formed as main phase together with beta-quartz. SEM together with elemental imaging of polished cross section of 5% Cu-doped bulk glass and 3% Cu-doped frit compact after ceramming at 1000 °C for 10 hours in air. FIGS. 6A and 6B are SEM analysis of polished cross section of 5% Cu-doped bulk glass and 3% Cu-doped frit, respectively, compact after ceramming in air at 1000 °C for 10 hours. The bulk-glass-derived glass ceramic contains indialite/cordierite main crystalline phase with minor crystalline phases of gahnite, enstatite,

quartz and about 30% residual glass. The glass ceramic obtained from bulk glass (FIG. 6A) contains randomly distributed copper oxide particles and other Cu-containing oxide compounds. SEM cross section images of compacts of Cu-doped frit pellets show successful sintering of the frit compact into a dense glass ceramic pellet with the same phases, but show an alignment of CuO-containing phases along the ghost networks (FIG. 6B). The inset in FIG. 6B is an enlargement that shows the Cu-0 rich phases as bright areas or bright dots.

[00133] The example demonstrates that decoration of the ghost networks with copper oxide can be obtained in a suited ceram/densification cycle. Concentrations of 5 mass% CuO or 3 mol% CuO provide decoration of ghost networks, but not a continuous decoration line. Higher Cu-concentrations in the initial glass promote continuity of the decoration.

[00134] Reductive sinter-ceramming was realized in a direct ceram-sintering cycle in reducing environment or in a 2-step process with a ceram-sintering cycle for decoration of the first boundaries with CuO in a first step and a reduction in a second step under reducing environment. FIGS. 7A - 7D present SEM images of polished cross sections of CORD03 and CORD04 frit compacts containing copper in the glass composition after ceramming in 5% H₂/Ar. FIG. 7A is an SEM image of a coarse frit of CORD03 containing 3% copper oxide cerammed at 950 °C/1 hour, and FIG. 7B is an SEM image of a fine frit of CORD03 containing 3% copper oxide cerammed at 1000 °C/1 hour. FIG. 7C is an SEM image of a coarse frit of CORD04 containing 5% copper oxide cerammed at 950 °C/1 hour, and FIG. 7D is an SEM image of a fine frit of CORD04 containing 5% copper oxide cerammed at 1000 °C/1 hour. The glass ceramic contains indialite/cordierite as main crystalline phase, about 30% glass, metallic copper, and minor phases of gahnite, enstatite, BaMg2Al6Si9(¾o and quartz. In the material made from fine frits, copper network cells are not well defined, while, in coarse frits, copper decorates the border of the frit particles and forms a clearly defined cell structure with copper. Fine frits sinter more easily than coarse frits and produce dense material at 1000 °C/1 hour, while at similar conditions; the coarse frit is not densified.

EXAMPLE 2

[00135] Bulk glasses, coarse and fine frits of compositions L1S01 - L1S04 in Table 1 , were used for making Li-silicate glass ceramics using different ceram cycles. The goal was again to decorate ghost networks in pressed frit pellets with metallic copper and achieve substantial conductivity along the copper ghost network. Cu-free and Cu-containing bulk glasses were used as a reference for the corresponding bulk glass-derived glass ceramics.

[00136] The Li-silicate compositions were chosen as a second example, since in these frits crystallization occurs much earlier than sintering and the ceram-sinter-reduction process cannot be realized above the sintering threshold because of partial melting and rearrangement of the microstructure at these temperatures. Thus it is already a first challenge to reach full densification of the frits and then a second to decorate the ghost networks in material that undergoes early and easy bulk crystallization.

[00137] DSC and TMA analysis conducted in air for bulk glasses, coarse frits, and fine frits having the compositions of L1S01 - L1S04 are shown in FIGS. 8A - 8D. The DSC analysis of bulk glass is shown in FIG. 8A, the DSC analysis of coarse frit is shown in FIG. 8B, and the DSC analysis of fine frit is shown in FIG. 8C. The TMA analysis is shown in FIG. 8D. The DSC analysis in FIGS. 8A - 8C are very similar for each of the glass types, suggesting that surface nucleation and crystal growth do not play a dominant role and that bulk nucleation and crystallization occur easily. Initial crystallization seems to be unaffected by copper and, according to XRD analysis, seems to relate to the induction of nucleation by phosphorous and crystallization and crystal growth around 600 °C. The DSC analysis shows that for both, bulk glasses and frits, the crystallization of the main phases is promoted by Cu-doping and shifted to increasingly lower temperature with increasing Cu-level. DSC comparison also shows a much sharper peak for the crystallization in presence of copper doping. Cu-doped glasses show in addition to the main crystallization peaks a small broad peak around 800 °C. Partial melting onset is also earlier for Cu-doped glasses and shows a more pronounced split of different melting events. While undoped glass shows first melting events at 900 °C, glass frit with 5% Cu-doping level shows first melting events around 820 °C in air. Melting occurs in several partial melting events with stabilization by rearrangement and/or recrystallization.

[00138] The TMA analysis in air, as shown in FIG. 8C, reveals several shrinkage events, each associated with crystallization, reaction, dissolution or melting. Strong shrinkage starts at 870 °C for 3% Cu or 920 °C for 0% Cu, but shows a plateau and stabilization at 900 °C for Cu-doped frit or 970 °C for undoped frit, which then leads at about 30 °C higher temperature to rapid shrinkage due to extensive melting.

[00139] Onset of shrinkage and sintering for these frits are occurring in very different temperature regions, suggesting that it will be difficult to crystallize/densify/reduce simultaneously. Effectively sintering occurs once crystallization is completed. This example was chosen as illustration for a glass with lacking overlap of sintering with crystallization and illustrates the impact on continuous copper decoration along the ghost networks in a reduction-ceram process.

[00140] XRD of frit pellets that were cerammed at different temperatures in reducing environment (5% H₂/Ar) reveals a minor initial crystallization at 580 °C. Again crystallization is more advanced in the Cu-containing frits. In Cu-free frit pellets, some not very well defined α/β-quartz and several mixed LiAl-silicates or Li-phosphosilicates are found. In frit formed from L1S03 with 3% Cu Li phyllo- disilicate L1₂S1₂O₅, ot-quartz and metallic copper are found. At 720 °C, crystallization is well advanced in all compositions of L1S01 - L1S04 with L1₂S1₂O5 and β-quartz being the main phases. In Cu-free compositions, small crystallites of L1₃PO₄ are also present. Metallic copper is present in all compositions containing copper. Upon high temperature ceramming above 850 °C, where DSC suggests partial melting, L1₂S1₂O5, stuffed β-quartz and Cu (for Cu-containing compositions) remain the main phases, but at 880 °C and even more at 920 °C, additional crystallized phases are observed in the cooled samples, including β-spodumene (at 920 °C it is present up to 19%), enstatite (5%), L1₃PO₄ (5% - 6%).

[00141] Compacts of Cu-free frit do not exhibit any sintering at temperatures as high as 850 °C, while high copper level frit pellets show some initial sintering between frit particles after ceramming at 850 °C/2 hours. FIGS. 9A - 9D are SEM cross sectional images of cerammed compacts of 5 wt% Cu-LiSi frits after annealing in air at 850 °C/2 hours. FIGS. 9A - 9B show complete crystallization into L1₂S1₂O₅ and β-quartz and only a slightest onset of sintering, so that a very porous compact is obtained. FIG. 9 A is a back-scatter detector (BSE) image at low magnification that shows the individual frit particles in the cerammed pellet and demonstrates insufficient sintering. FIG. 9B is Cu elemental image of a frit particle surface that shows strong copper segregation to the surface. FIG. 9C is an SEM image and FIG. 9D is a Cu elemental image that together show crystallization across the entire bulk of the frit particles of CuO, Li₂Si205 and β- quartz phases.

[00142] Occasional large streaks of MgCu enstatite are observed growing from the frit particle surfaces into the bulk. A more homogeneous glass ceramic micro structure of L1₂S1₂O5 and β-quartz with decoration of the frit particle boundaries by CuO or its compounds is obtained at higher temperature.

[00143] FIGS. 10A and 10B present SEM cross sectional images of cerammed compacts of 3% Cu-LiSi frit after annealing in air at 1000 °C. A decoration of the ghost networks by CuO-containing phases is noticed as discontinuous white lines in FIG. 10A. The resulting glass ceramic is highly porous (black or dark grey contrast). Higher magnification SEM image in FIG. 1 OB shows the discrete nature of the CuO decoration. It also reveals a very regular micro structure of the two phase glass ceramic of stuffed beta quartz and Li- silicate. At the high temperatures, meta-silicate and spodumene form from the disilicate of lithium. Ceramming at temperatures above the partial melting temperature allow making denser glass ceramic but the partial melting induces also phase changes. In air decoration of ghost networks by Cu-oxide compounds is observed but the decoration is still discontinuous. Higher Cu-levels may be needed in the glass or optimized pO/T cycles.

[00144] FIGS. 11 A and 11B are SEM fracture surface images of cerammed 5 wt% Cu-LiSi frit compacts after annealing in 5% H₂/Ar at 835 °C/2 hours and after annealing at 900 °C/10 hours, respectively. FIGS. 1 1A and 11B show that that crystallization occurs under both conditions. At the lower temperature, reduction to metallic copper preferentially occurs on large frit particle surfaces, but at higher temperature, reduction to metallic copper occurs across all frit particle sizes. For both annealing temperatures, sintering and densification remain insufficient in these ceram cycles.

[00145] FIGS. 12A and 12B are SEM polish cross section images and Cu elemental maps, respectively, of cerammed frit compacts after ceramming in 5% H2/Ar for glass composition L1S03 containing 3% copper after annealing at 920 °C for 8 hours. FIGS. 12C and 12D are SEM polish cross section images and Cu elemental maps, respectively, of cerammed frit compacts after ceramming in 5% H₂/Ar for glass composition L1S04 containing 5% copper in the glass after annealing at 920 °C for 5 hours. In both cases, decoration of the ghost networks by metallic copper (white contrast in the SEM image and high artificial color contrast in the Cu elemental map) is seen. The resulting glass ceramic is dense and crystallization of Li-silicate and β-quartz is completed; there is no partial melting and decomposition, and recrystallization in the desired phases has occurred.

EXAMPLE 3 [00146] For this example on calcium alumino silicates, the glass used without copper was CAS01. In particular the crystalline phase of the glass ceramic is yoshiokaite, which is a phase with a structure derived from tridymite and a composition close to CasjAli

For instance, the yoshiokaite used in this example may be made in the same manner as the yoshiokaite disclosed in concurrently filed application US 62/552,657 entitled "Yoshiokaite Glass Ceramics Obtained From Glass Frits", filed 8/31/2017, which is incorporated herein by reference in its entirety Crystallization in the precursor glass of same composition is limited to the surface. Therefore, glass ceramics cannot be made from bulk glass. Glass ceramics can only be made from frit.

[00147] FIG. 13 is an SEM micrograph of a Yoshiokaite glass-ceramic after ceramming CASOl pellets for 5 hours at 1010 °C in air. A fully dense glass ceramic is obtained despite the fact that crystalline phase can only be formed in this system by surface nucleation. In the frit pellet, crystallization occurs at the surface of each frit particle. The crystallization of the Yoshiokaite precursor glass is relatively unusual, since it is almost congruent with nucleation. The resulting glass-ceramic contains only a very low amount of residual glass, as shown in FIG. 13, that is not visible in the XRD trace, which are discussed below and provided in FIGS. 17A - 17C. The boundaries between the crystals show brighter contrast in the SEM image of FIG. 13 because of CaO enrichment at the grain boundaries.

[00148] The DSC analysis provided in FIG. 14A shows a significant temperature difference between Tg and crystallization. The DSC analysis shown in FIG. 14A was conducted in an Ar atmosphere at a heating rate 10 °C/min. The TMA analysis shown in FIG. 14B was conducted in an Ar atmosphere at a heating rate 10 °C/min on frit pellets having the compositions of CASOl - CAS04. The DSC analysis in FIG. 14A shows one main exothermal sharp peak that corresponds to the crystallization of Yoshiokaite. For the Cu-free frit, crystallization starts around 1000 °C, while for Cu-containing glasses, the crystallization onset is shifted to a temperature about 100 °C lower. Crystallization occurs earlier in the compositions having higher copper content in the glass. Substantial sintering starts in the same temperature range as crystallization. The TMA analysis shown in FIG. 14B for the different frit pellets shows a single shrinkage event with a sintering event around about 960 °C for Cu-free frit and around 900 °C for Cu-containing frit. Again densification occurs at lower temperature when copper oxide is present in the glass and densification occurs earlier in the glasses having higher copper oxide content in the glass.

[00149] The temperature difference between Tg and crystallization shown in FIG. 14A suggests that minor sintering already occurs before crystallization can take place, which allows bulk glass ceramic parts with very low porosity to be obtained. FIGS. 15A and 15B are SEM and Cu elemental images, respectively, of frit pellet CAS02 (5% copper oxide) after ceramming for 5 hours at 960 °C in air, and show a dense Yoshiokaite glass ceramic with a decoration of the ghost networks by copper oxide. Energy dispersive analysis in the SEM reveals some segregation of calcium to the ghost networks, visible as bright lines in the SEM image of FIG. 15 A.

[00150] FIGS. 16A - 161 are SEM images, EDX spectrum, and Cu elemental images of polished cross-sections of copper oxide-containing Ca-Al-silicate glass frit pellets after ceramming in reducing environment. In the SEM images shown in FIGS. 16A, 16D, and 16G, Yoshiokaite appears with grey contrast, metallic copper with bright contrast and pores are dark. The Cu-elemental images of FIGS. 16C, 16F, and 161 highlight the ghost network decoration by copper, showing copper rich areas in high contrast in the chosen artificial color. FIGS. 16A - 16C are an SEM image, an EDX spectrum, and a Cu elemental image, respectively, of a Pellet of CAS02 coarse frit (CAS02 is a Yoshiokaite composition containing 5% copper oxide in the glass) that was cerammed for 5 hours at 960 °C in 5% H₂/Ar, showing the resulting Yoshiokaite glass ceramic with a decoration of its frit grain boundaries by metallic copper (the representative EDX spectrum of a grain is shown, revealing the absence of copper within the crystallized grains). FIGS. 16D - 16F are an SEM image, an EDX spectrum, and a Cu elemental image, respectively, of a Pellet of CAS03 coarse frit (CAS03 is a Yoshiokaite containing 7% copper oxide in the glass) that was cerammed for 5 hours at 930 °C in 5% H₂/Ar and show the resulting Yoshiokaite glass ceramic with a decoration of its frit grain boundaries by metallic copper. FIGS. 16G - 16H are an SEM image, an EDX spectrum, and a Cu elemental image, respectively, of a Pellet of CAS04 coarse frit (CAS04 is a Yoshiokaite containing 10% copper oxide in the glass) that was cerammed for 5 hours at 960 °C in 5% H₂/Ar, and show the resulting Yoshiokaite glass ceramic with a decoration of its frit grain boundaries by metallic copper.

[00151] FIG. 17A is x-ray diffraction results of a Cu-free CASOl frit pellet after ceramming for 5 hours at 950 °C in air. FIG. 17A reveals Yoshiokaite as the main phase (97.6 wt% according to Rietveld quantification), ot-quartz, and gehlenite as minor phases (0.5 wt% and 1.9 wt%, respectively). There is no visible residual glass. FIG. 17B is x-ray diffraction results of a Cu-containing CAS02 (5% copper oxide) frit pellet after ceramming for 5 hours at 960 °C in air, and shows Yoshiokaite as main phase together with several minor phases, including gehlenite, cristobalite and β-quartz; copper oxide is not identified in the spectrum and assumed to be contained in solid solution. FIG. 17C is x-ray diffraction results of a Cu-containing CAS02 (5% copper oxide) frit pellet after ceramming for 5 hours at 960 °C in 5% t^/Ar, and shows Yoshiokaite as main phase together with metallic copper; no residual glass is detected.

EXAMPLE 4

[00152] In example 4, copper-free glass frits were mixed with fine powder of metallic copper or cuprous oxide. The mixtures covered a range from 0 to 75 vol% copper. Glass and copper powders were mixed in a tubular mixer and then cold-pressed into pellets of 10-35 mm diameter and several millimeter in height. Powder mixtures were made from fine and coarse lithium silicate glass powders, L1S01 and L1S07 without any copper in their glass compositions, and 10 wt%, 20 wt%, 12.5 vol%, 18.75 vol%, 25 vol%, 50 vol%, 75 vol% of nanometric metallic copper powder. Powder mixtures were also made from calcium aluminum silicate glass powders, CASOl containing no copper in its glass compositions and 7 wt%, 10 wt%, 12.5 vol%, 18.75 vol%, 25 vol%, 50 vol%, 75 vol% of nanometric metallic copper powder. Another powder mixture was made from CAS02 that contains in its glass composition already 5.5 wt% CuO and 3 wt% nanometric copper powder, The pellets were then exposed to reducing ceram cycles. The annealing conditions and different mixtures are listed in Table 9. The annealed pellets with high copper content showed the aspect of metallic copper at their surface and in the bulk. Around 50 vol%, the pellets adopted a more brownish tint.

[00153] Glass powders were also mixed with copper oxide powders in a tubular mixer, cold-pressed into pellets of 10-35 mm diameter and several millimeters in height and then exposed to reducing ceram cycles. Coarse and fine frits of L1S01 and L1S07 were mixed with 10 wt% CuO and cerammed in a reducing ceram cycle. The aspect of the sample, their microstructure and phase combination were identical to those of the corresponding samples made with metallic copper in the powder mixture. No advantage or disadvantage was observed. Powder mixtures and annealing conditions are listed in Table 10 together with the mixtures and annealing conditions of frit-metallic copper mixtures.

[00154] Table 10 - Powder Mixtures and Annealing Conditions

[00155] The surfaces of the reduced samples of example 4 were measured with a multimeter at room temperature between two spots on the surface across a distance of 10 mm. Those values are listed in Table 10 as "surface conductivity" in ohm/cm. The conductivity across the sample was also measured at room temperature after removing the outer surface layer from the sample. The resistance for a sample of surface area A and sample thickness D were measured and normalized to specific resistivity at room temperature Rspec(RT)= R(RT) x A/D. Specific resistivity at room temperature was added in the table. For some samples the conductivity at high temperature in Ar/3% H₂ environment was measured in a closed tube furnace with gas flow. Data from those measurement are also tabulated in Table 10 as specific resistivity at given temperature T=xxxC as Rspec(T=xxxC).

[00156] Green bulk glasses, green Cu-free frit pellets, cerammed Cu-free bulk glass and cerammed Cu-free frit pellets showed very high resistance at room temperature that was beyond the measurement range of the test equipment. Cerammed compacts made with low levels of Cu or CU2O powder also showed no substantial room temperature electrical conductivity; their resistance was generally beyond the measurable range of the test equipment (10⁶ ohm).

[00157] Cerammed compacts made from mixtures of glass powder and Cu powder showed increasing room temperature electrical conductivity with increasing copper content. Compacted, annealed LISOl+Cu mixtures with 29 and more vol% Cu all showed room temperature specific bulk resistivity < 1 ohm cm, while for mixtures with 15 vol% Cu high resistivity was found. No major differences were observed when using coarse or fine frit. Coarse frit has a better distribution of copper than the fine, due to the lower specific specific area of coarse frit. Similar observations were made for compacted, annealed mixtures of CASOl with Cu powder. The threshold for reaching good conductivity was shifted to lower copper addition. CASOl -Cu composites reached room temperature bulk resistivity < 1 ohm cm at for >24 vol% Cu. Composites made with 15.5 vol% Cu exhibited 6.5 10⁴ ohm cm specific room temperature bulk resistivity after the compacting annealing; their resistivity decreased during further temperature cycling in reducing environment to 850 ohm cm. Measurements were realized on core drilled samples of the annealed compacts (eliminating all top, bottom and side surfaces, which could exhibit higher surface conductivity and falsify the measurements)

[00158] Electrical conductivities are shown in Table 11 , thermal conductivities are shown in Table 12, and mechanical properties are given in Table 13. The table includes bulk glasses, frit compacts with copper and without copper in their glass composition cerammed in air and in 3% H₂/Ar and cerammed powder mixtures of glass frits (containing no copper in their glass composition) with nanopowder of metallic copper.

Table 1 1 - Electrical Conductivity Data.

Table 12 - Thermal Conductivity Data.

Table 13 - Mechanical Data

[00159] As can be seen from the measurements in Table 10 that all bulk glasses are insulators at room temperature, their electrical conductivity cannot be measured at room temperature, or is extremely low. Lithium silicate bulk glasses exhibit some ionic conductivity, so that their overall bulk conductivity becomes measurable once the lithium ions gain sufficient mobility in the glass. Thus resistivity for the bulk glass becomes measurable at high temperatures.

[00160] Glass ceramics made from CAS bulk glass, CAS glass frit of glasses with 8 wt% or less CuO in the starting glass by various ceram cycles in air or reducing environment do not show any surface or bulk conductivity at room temperature.

[00161] For powder mixtures of CuO-free CASOl frit and nanometric metallic copper powder at Cu volume fractions from 8 to 80 vol%, these materials were pressed into pellets and cerammed in a reducing ceram cycle (listed in Table 9). Glass ceramics as shown in FIG. 18 were obtained that covered a wide range of surface and bulk conductivities. FIG. 18 shows SEM views of sample surfaces and polished cross sections after ceramming in reducing environment pressed pellets of powder mixtures of CASOl frit and metallic copper. Copper powder fractions cover 17-80 vol% as indicated. In all images, the metallic copper phase appears in bright contrast and the yoshiokaite Ca-Al-silicate crystalline phase in darker grey. The cerammed materials with 80.4 vol%, 58.7 vol%, and 24.7 vol% metallic copper looked metallic and showed metallic bulk resistivity < 1 ohm cm, respectively. The cerammed material made with 15.5 vol% Cu powder showed an intermediate bulk resistivity of 170 ohm cm after thermal cycling or 2400 ohm cm after processing.

[00162] Powder mixtures of CuO-free L1S01 coarse or fine frit and nanometric metallic copper powder at Cu volume fractions from 15 to 79 vol% were pressed into pellets and cerammed in a reducing ceram cycle (listed in Table 9). The resulting glass ceramics covered a wide range of surface and bulk conductivities. No differences were observed for use of fine and coarse frit of L1S01. The cerammed materials with 79 vol%, 56 vol%, and 30 vol% metallic copper looked metallic and showed all a metallic room temperature bulk resistivity < 1 ohm cm (including the contact resistances). The cerammed material made with 15.5 vol% Cu powder shows high room temperature bulk resistivity.

EXAMPLE 5

[00163] Glass powders were surface coated in these examples with a solution of a metal salt, the coated powders were then dried, pressed into a powder pellet and cerammed in a reducing ceram cycle, in which the metal salt was reduced to metal. We used as example the calcium aluminum silicate glass powder CAS03 that obtained 8.3 wt% CuO in its glass composition. The glass powder particles were coated with Cu, Fe, Ni-salts, simple salts or solutions of several salts at levels of 0.5 - 3 wt% compared to the glass powder. The compressed compacts were cerammed at an exemplary temperature of 920 °C for 5h in 97%Ar/3%H2. The resulting glass ceramics show an improved interconnectivity of the metal network compared to glass ceramics made for the uncoated glass powder. The results are shown in Table 14 below.

[00164] Table 14 - Ceram cycles for pellets of Ca- Al-silicate -type frit coated with salts

EXAMPLE 6 [00165] Difficulties related to the densification of frits due to early crystallization can be overcome by applying a stress during the ceram cycle. Controlled stress can be applied in a uniaxial hot press, SPS or isostatic hot press, less controlled stress by placing a heavy weight on the sample. Various frit pellets were cerammed, including the compositions of L1S01 - L1S04, CASOl - CAS04, and CORDOl - CORD04 in SPS in graphite dies under vacuum, using various heating rates and top temperatures and hold times. Effectively, under stresses of 2 - 10 kPa, it was possible to fully densify all frits and at significantly lower temperature.

[00166] FIG. 19A and FIG. 19B show an SEM polished cross section of 5wt%Cu-LiSi frit compacts after pressure-ceramming in reducing environment (vacuum, graphite die) at 800 °C/7KN/45min. FIGS. 19A and 19B show that a dense glass ceramic was made with decoration of the ghost networks by metallic copper (white contrast); the ghost network is discontinuous under this condition. The example shows that full densification of the frit pellet can be achieved under stress or high pressure. The pressure ceramming under reducing environment allows a bridging of the gap between early crystallization and melting and sluggish sintering and thus overcome the problems of ceramming in natural sintering cycles.

[00167] It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Thus it is intended that the specification cover the modifications and variations of the various embodiments described herein provided such modification and variations come within the scope of the appended claims and their equivalents.

Claims

What is claimed is:

1. A glass ceramic composite comprising:

a plurality of cells forming a glass ceramic microstructure; and

a ghost network surrounding and separating individual cells of the plurality of cells,

wherein the ghost network is a discontinuity in the microstructure, and wherein a metal decorates at least a portion of the ghost network.

2. The glass ceramic composite of claim 1, wherein a porosity of the glass ceramic composite is less than or equal to 5%.

3. The glass ceramic composite of any of claims 1 and 2, wherein the metal that decorates at least a portion of the ghost network comprises at least one metal of Groups Vl-Xll of the periodic table.

4. The glass ceramic composite of any of claims 1 through 3, wherein the metal that decorates at least a portion of the ghost network comprises at least one metal of Group 1X-X11 of the periodic table.

5. The glass ceramic composite of any of claims 1 through 4, wherein the metal that decorates at least a portion of the ghost network comprises a metal selected from the group consisting of copper, nickel, silver, zinc, tin, cobalt, and mixtures thereof.

6. The glass ceramic composite of any of claims 1 through 5, wherein at least 95% of all metals present in the glass ceramic composite are located in the ghost network.

7. The glass ceramic composite of any of claims 1 through 6, wherein the glass ceramic composite comprises yoshiokaite as a crystalline phase.

8. The glass ceramic composite of any of claims 1 through 7, wherein the glass ceramic composite comprises cordierite as a crystalline phase.

9. The glass ceramic composite of any of claims 1 through 8, wherein the glass ceramic composite comprises at least one of lithium meta silicate, lithium disilicate, and beta-quartz as a crystalline phase.

10. The glass ceramic composite of any of claims 1 through 9, wherein the metal that decorates at least a portion of the ghost network forms a continuous metal network.

11. The glass ceramic composite of any of claims 1 through 10, wherein the metal that decorates at least a portion of the ghost network forms a discontinuous metal network.

12. The glass ceramic composite of any of claims 1 through 1 1, wherein the plurality of cells have a size greater than or equal to 1 μm to less than or equal to 100 μm.

13. The glass ceramic composite of any of claims 1 through 12, wherein the plurality of cells have a size greater than or equal to 10 μm to less than or equal to 50 μm.

14. The glass ceramic composite of any of claims 1 through 13, wherein the glass ceramic composite comprises residual glass in amounts from greater than or equal to 2 mass% to less than or equal to 30 mass%.

15. The glass ceramic composite of any of claims 1 through 14, further comprising a first surface and an opposing second surface, wherein the ghost network provides at least one conductive pathway from the first surface to the second surface.

16. The glass ceramic composite of claim 15, wherein the conductive pathway is electrically conductive.

17. The glass ceramic composite of any of claims 1 through 16, wherein the discontinuity in the micro structure comprises a difference in a chemical composition of the glass ceramic micro structure.

18. The glass ceramic composite of any of claims 1 through 17, wherein the discontinuity in the micro structure comprises a difference in a quantity, shape, or size of crystalline phases of the glass ceramic microstructure.

19. A method for manufacturing a glass ceramic composite comprising:

forming a glass powder comprising at least one oxide of a metal selected from Groups Vl-Xll of the periodic table into a green body of desired shape;

ceramming the green body by firing the green body using a heating rate from greater than or equal to 100 °C/ hour to less than or equal to 350 °C/hour to a hold temperature from greater than or equal to 600 °C to less than or equal to 1200 °C and holding the green body at the hold temperature for a duration from greater than or equal to 1 hour to less than or equal to 20 hours, wherein

the glass ceramic composite comprises:

a plurality of cells forming a glass ceramic microstructure; and a ghost network surrounding and separating individual cells of the plurality of cells, wherein the ghost network is a discontinuity in the microstructure, and wherein a metal decorates at least a portion of the ghost network.

20. The method of claim 19, wherein a porosity of the glass ceramic composite is less than or equal to 5%.

21. The method of any of claims 19 and 20, wherein the at least one oxide of a metal comprises at least one oxide of a metal selected from Group 1X-X11 of the periodic table.

22. The method of any of claims 19 through 21, wherein the at least one oxide of a metal is selected from the group consisting of oxides of copper, nickel, silver, zinc, tin, cobalt, and mixtures thereof.

23. The method of any of claims 19 through 22, wherein the at least one metal is batched as superaddition to a glass composition in an amount from greater than or equal to 5 mass% to less than or equal to 80 mass%.

24. The method of any of claims 19 through 23, wherein the ceramming is conducted in a reducing atmosphere comprising oxygen at low partial pressure, argon, nitrogen, hydrogen, carbon monoxide, carbon dioxide and mixtures thereof.

25. The method of any of claims 19 through 24, wherein the ceramming is conducted in a reducing atmosphere comprising from greater than or equal to 2.0 vol% to less than or equal to 5.0 vol% H₂ and a remainder being argon.

26. The method of any of claims 19 through 25, wherein the glass powder has a median particle size from greater than or equal to 5 μm to less than or equal to 50 μm, a dio particle size distribution less than or equal to 3.0 μηι, and a d₉₀ particle size distribution from greater than or equal to 10 μm to less than or equal to 100 μm.

27. The method of any of claims 19 through 26, wherein the glass powder has a median particle size from greater than or equal to 10 μm to less than or equal to 30 μm, a dio particle size distribution from greater than or equal to 6 μm to less than or equal to 12 μm, and a d₉₀ particle size distribution from greater than or equal to 10 μm to less than or equal to 80 μm.

28. An electronic device, comprising:

electrical components; and

a glass ceramic composite component comprising the glass ceramic composite of any of claims 1 through 18 electrically connected to the electrical components.