WO2021133535A1

WO2021133535A1 - Glass manufacturing apparatus and methods for processing a molten material

Info

Publication number: WO2021133535A1
Application number: PCT/US2020/063186
Authority: WO
Inventors: HyunMo HA; Yongseop HAN
Original assignee: Corning Incorporated
Priority date: 2019-12-24
Filing date: 2020-12-04
Publication date: 2021-07-01
Also published as: TW202134191A; KR20210081554A

Abstract

Glass manufacturing apparatus can include a ceramic body with a surface. A coating can be deposited on the surface. The coating can include alkali metal or alkali-earth metal in a range from about 1.3% to about 50% by weight on an oxide basis. Methods of processing a molten material can include heating a ceramic body from a first temperature in a range from about 0°C to about 100°C to a second temperature in a range from about 1400°C to about 1700°C. Methods can include a particulate coating deposited on the surface of the ceramic body, where the particular coating comprises alkali metal or alkali-earth metal in a range from about 1.3% to about 50% by weight on an oxide basis. Methods can also comprise the particulate coating forming a glass layer during the heating. Methods can also comprise contacting the glass layer with the molten material.

Description

GLASS MANUFACTURING APPARATUS AND METHODS FOR PROCESSING A

MOLTEN MATERIAL

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of priority under 35 U.S.C. § 119 of Korean Patent Application Serial No. 10-2019-0173643 filed on December 24, 2019 the content of which is relied upon and incorporated herein by reference in its entirety.

FIELD

[0001] The present disclosure relates generally to glass manufacturing apparatus and methods for processing a molten material and, more particularly, to glass manufacturing apparatus and methods for processing a molten material comprising a coating deposited on a ceramic body.

BACKGROUND

[0001] Glass articles are commonly used, for example, in display devices, such as, liquid crystal displays (LCDs), electrophoretic displays (EPD), organic light emitting diode displays (OLEDs), plasma display panels (PDPs), touch sensors, photovoltaics, or the like.

[0002] It is known to form glass articles from molten material. An example of a glass article is a separated glass ribbon, which is commonly separated from glass ribbons formed by flowing molten material to a forming body. The molten material is commonly generated by heating batch material within a melting vessel, for example a melting vessel comprising a ceramic body. Other vessels, including fining vessels and delivery vessels may also comprise a ceramic body and contact molten material.

[0003] It is known to heat vessels comprising a ceramic body to an operating temperature, which may be in excess of 1000°C. These vessels may crack if they are heated too quickly and/or non-uniformly. Additionally, these vessels may corrode as a result of contact with molten material. Further, the ceramic body may contaminate the molten material as a result of cracking and/or corrosion.

[0004] Consequently, there is a need for methods of processing molten material that reduce and/or prevent cracking of vessels during heating. Further, there is a need for methods of processing molten material that reduce and/or prevent corrosion of vessels. SUMMARY

[0005] Some example embodiments of the disclosure are described below with the understanding that any of the embodiments may be used alone or in combination with one another.

[0006] In some embodiments, a glass manufacturing apparatus can comprise a ceramic body comprising a surface. A coating can comprise an alkali metal or an alkali-earth metal in a range from about 1.3% to about 50% by weight on an oxide basis deposited on the surface.

[0007] In further embodiments, the ceramic body can comprise zirconia.

[0008] In even further embodiments, the zirconia can be in a range from about 50% to about 99% by weight of the ceramic body.

[0009] In even further embodiments, the zirconia can comprise zirconia grains. The ceramic body can further comprise an intergranular glass phase.

[0010] In further embodiments, the coating can comprise the following oxides in weight %: S1O2 in a range from about 30% to about 85%; AI2O3 in a range from 0% to about 30%; B2O3 in a range from 0% to about 10%; and Na₂0 in a range from about 6.5% to about 13%. The alkali metal or alkali-earth metal can comprise Na₂0.

[0011] In further embodiments, the coating can comprise a particulate coating.

[0012] In even further embodiments, the particulate coating can comprise particles comprising a median particle size in a range from about 5 micrometers to about 15 micrometers.

[0013] In further embodiments, the coating can comprise a glass layer.

[0014] In further embodiments, the surface of the ceramic body can define a containment region.

[0015] In further embodiments, the ceramic body can comprise a melting vessel.

[0016] In some embodiments, a method of processing molten material can comprise heating a ceramic body from a first temperature in a range from about 0°C to about 100°C to a second temperature in a range from about 1400°C to about 1700°C. The ceramic body can comprise a surface. A particulate coating can be deposited on the surface. The particulate coating can comprise an alkali metal or an alkali-earth metal in a range from about 1.3% to about 50% by weight on an oxide basis. The particulate coating can form a glass layer during the heating. The method can also comprise contacting the glass layer with the molten material. [0017] In further embodiments, prior to the heating the ceramic body, the method can further comprise depositing the particulate coating by depositing a slurry comprising water, a thickening agent, sodium oxide, and silica on the ceramic body.

[0018] In even further embodiments, the thickening agent can comprise methyl cellulose.

[0019] In even further embodiments, after the depositing the slurry, the method can further comprise drying the slurry from about 6 hours to about 168 hours to form the particulate coating before the heating the ceramic body.

[0020] In further embodiments, the particulate coating can comprise the following oxides in weight %: S1O2 in a range from about 30% to about 85%; AI2O3 in a range from 0% to about 30%; B2O3 in a range from 0% to about 10%; and Na₂0 in a range from about 6.5% to about 13%. The alkali metal or alkali-earth metal can comprise Na₂0.

[0021] In further embodiments, the particulate coating can comprise particles comprising a median particle size in a range from about 5 micrometers to about 15 micrometers.

[0022] In further embodiments, the ceramic body can comprise zirconia.

[0023] In even further embodiments, the zirconia can be in a range from about 50% to about 99% by weight of the ceramic body.

[0024] In even further embodiments, the zirconia can comprise zirconia grains. The ceramic body can further comprise an intergranular glass phase.

[0025] In still further embodiments, a concentration of alkali metal or alkali-earth metal in the intergranular glass phase between the surface and 900 micrometers from the surface in a bulk of the ceramic body can increase from a first concentration to a second concentration while the ceramic body is heated.

[0026] In yet further embodiments, the first concentration can be about 1.3% or less by weight on an oxide basis.

[0027] In yet further embodiments, the second concentration can be in a range from about 1.5% to about 3% by weight on an oxide basis.

[0028] In further embodiments, the molten material can be contained within a containment region defined by the surface of the ceramic body.

[0029] In further embodiments, the method can further comprise forming a glass article or a glass-ceramic article from the molten material.

[0030] Additional embodiments disclosed herein will be set forth in the detailed description that follows. It is to be understood that both the foregoing general description and the following detailed description present embodiments intended to provide an overview or framework for understanding the nature and character of the embodiments disclosed herein. The accompanying drawings are included to provide further understanding and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the disclosure, and together with the description explain the principles and operations thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] These and other embodiments are better understood when the following detailed description is read with reference to the accompanying drawings, in which:

[0032] FIG. 1 schematically illustrates an exemplary embodiment of a glass manufacturing apparatus in accordance with some embodiments of the disclosure;

[0033] FIG. 2 is an enlarged view 2 of FIG. 1 in accordance with some embodiments of the disclosure;

[0034] FIG. 3 schematically illustrates a step in a method of making a glass manufacturing apparatus in accordance with some embodiments of the disclosure;

[0035] FIG. 4 schematically illustrates another step in a method of making a glass manufacturing apparatus in accordance with some embodiments of the disclosure;

[0036] FIG. 5 schematically illustrates another step in a method of making a glass manufacturing apparatus in accordance with some embodiments of the disclosure;

[0037] FIG. 6 is a flow chart illustrating example methods making a foldable apparatus in accordance with the embodiments of the disclosure;

[0038] FIG. 7 is a schematic representation of a scanning electron microscope (SEM) image of a zirconia sample at 1400°C comprising less than 0.01 weight % (% wt) sodium;

[0039] FIG. 8 is a schematic representation of a scanning electron microscope (SEM) image of a zirconia sample at 1400°C comprising 0.1 % wt sodium;

[0040] FIG. 9 is a schematic representation of a scanning electron microscope (SEM) image of a zirconia sample at 1400°C comprising 0.2 % wt sodium;

[0041] FIG. 10 is a plot illustrating experimental results for zircon-forming depth as a function of sodium oxide concentration; and

[0042] FIG. 11 is a plot illustrating simulation results of normalized zircon formation as a function of sodium oxide concentration.

DETAILED DESCRIPTION

[0043] Embodiments will now be described more fully hereinafter with reference to the accompanying drawings in which example embodiments are shown. Whenever possible, the same reference numerals are used throughout the drawings to refer to the same or like parts. However, this disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[0044] The present disclosure relates to methods for processing molten material that may use manufacturing apparatuses and may be employed in methods for manufacturing a glass or glass-ceramic article (e.g., a glass ribbon) from a quantity of molten material. For example, FIGS. 1-2 illustrate a glass manufacturing apparatus comprising a down-draw apparatus (e.g., fusion down-draw apparatus). Unless otherwise noted, a discussion of features of embodiments of the glass manufacturing apparatus can apply equally to corresponding features of other forming apparatuses used in the production of glass or glass- ceramic articles. Examples of glass forming apparatuses include a slot draw apparatus, float bath apparatus, down-draw apparatus, up-draw apparatus, press-rolling apparatus or other glass article manufacturing apparatus that can be used to form a glass article (e.g., glass ribbon) from a quantity of molten material. In some embodiments, a glass article (e.g., glass ribbon) from any of these processes may then be divided to provide a plurality of glass articles (e.g., separated glass ribbons) suitable for further processing into a device (e.g., a display device). For example, separated glass ribbons can be used in a wide range of devices comprising liquid crystal displays (LCDs), electrophoretic displays (EPDs), organic light emitting diode displays (OLEDs), plasma display panels (PDPs), touch sensors, photovoltaics, appliances (e.g., stovetops), or the like.

[0045] FIGS. 1-2 illustrate a glass manufacturing apparatus with a coating and/or glass layer deposited on a melting vessel and molten material therein. Unless otherwise noted, a discussion of features of embodiments where the coating can apply equally to corresponding features of other vessels in the glass manufacturing apparatus. For example, the coating and/or glass layer can also be deposited on one or more of a fining vessel, a mixing vessel, or a delivery vessel, where the corresponding vessel comprises a ceramic body.

[0046] Embodiments of the disclosure can decrease (e.g., reduce, prevent) contamination of molten material with material from a ceramic body. For example, pieces of material from a ceramic body can separate from a bulk of the ceramic body resulting from cracking of the ceramic body. In some embodiments, cracking of a ceramic body can occur during heating, for example, heating from an ambient room temperature to a steady-state operating temperature. In some embodiments, applying a coating comprising an alkali metal and/or an alkali-earth metal (e.g., in a range from about 1.3% to about 50% by weight on an oxide basis) to a surface of the ceramic body can drive alkali metal ions and/or alkali-earth metal ions into the ceramic body. In further embodiments, the alkali metal and/or alkali-earth metal containing coating can increase a concentration of alkali metal ions and/or alkali-earth metal-containing ions near the surface of the ceramic body (e.g., in a silica-containing intergranular glass phase between the surface and 900 micrometers from the surface in a bulk of the ceramic body). An increased concentration of alkali-metal and/or alkali-earth metal (e.g., ions) within the ceramic body can suppress cracking by decreasing (e.g., reducing, preventing) crystal grain formation and/or growth. In some embodiments, zircon formation can be decreased (e.g., reduced, prevented) in zirconia-containing ceramic bodies (e.g., ceramic bodies comprising zirconia in a range from about 50% to about 99% by weight). In further embodiments, providing a coating comprising sodium (e.g., sodium oxide) can provide the benefits of quickly diffusing into the ceramic body, diffusing far into the ceramic body, and/or decreasing zircon formation compared to other potential alkali metals and/or alkali-earth metals, for example, because of its small ionic radius and low charge. Consequently, embodiments of the disclosure allow the ceramic body to be heated quickly with a decreased risk of cracking.

[0047] Additionally, material from a ceramic body can separate from a bulk of the ceramic body as a result of corrosion of the material (e.g., crystal grain) and/or corrosion of an intergranular phase surrounding a crystal grain. Providing a coating (e.g., slurry, particulate coating, glass layer) contacting a surface of the ceramic body can decrease (e.g., reduce, prevent) contact of the surface of the ceramic body by the molten material. In some embodiments, the coating (e.g., slurry, particulate coating, glass layer) can serve as a physical barrier to the molten material contacting the surface of the ceramic body. In some embodiments, the coating (e.g., slurry, particulate coating, glass layer) can fill imperfections (e.g., irregularities, voids, surface roughness) on the surface of the ceramic body. Providing such a coating can decrease (e.g., reduce, prevent) the surface area of the surface of the ceramic body accessible to the molten material. Also, providing such a coating can decrease (e.g., reduce, prevent) dissolution of an intergranular phase surrounding crystal grains in the ceramic body. Moreover, embodiments of the disclosure can decrease (e.g., reduce, prevent) corrosion of the ceramic body in contact with molten material. Decreasing (e.g., reducing, preventing) corrosion of the ceramic body can extend the lifetime of the ceramic body. Further, reduced corrosion of the ceramic body can decrease (e.g., reduce, prevent) contamination of the molten material with material from the ceramic body. [0048] As schematically illustrated in FIG. 1, in some embodiments, a glass manufacturing apparatus 100 can comprise a glass melting and delivery apparatus 102 and a forming apparatus 101 comprising a forming vessel 140 designed to produce a glass ribbon

103 from a quantity of molten material 121. As used herein, the term “glass ribbon” refers to material after it is drawn from the forming vessel 140 even when the material is not in a glassy state (i.e., above its glass transition temperature). In some embodiments, the glass ribbon 103 can comprise a central portion 152 positioned between opposite edge portions formed along a first outer edge 153 and a second outer edge 155 of the glass ribbon 103. Additionally, in some embodiments, a separated glass ribbon 104 can be separated from the glass ribbon 103 along a separation path 151 by a glass separator 149 (e.g., scribe, score wheel, laser). In some embodiments, before or after separation of a separated glass ribbon

104 from the glass ribbon 103, the edge beads formed along the first outer edge 153 and the second outer edge 155 can be removed to provide the central portion 152 as a separated glass ribbon 104 having a more uniform thickness.

[0049] In some embodiments, the glass manufacturing apparatus 100 can comprise a melting vessel 105 oriented to receive batch material 107 from a storage bin 109. The batch material 107 can be introduced by a batch delivery device 111 powered by a motor 113. In some embodiments, a controller 115 can optionally be operated to activate the motor 113 to introduce an amount of batch material 107 into the melting vessel 105, as indicated by arrow 117. The melting vessel 105 can heat the batch material 107 to provide molten material 121. In some embodiments, a glass melt probe 119 can be employed to measure a level of molten material 121 within a standpipe 123 and communicate the measured information to the controller 115 by a communication line 125. The controller 115 can then activate the motor 113 to introduce additional batch material 107 into the melting vessel 105.

[0050] Additionally, in some embodiments, the glass manufacturing apparatus 100 can comprise a first conditioning station comprising a fining vessel 127 located downstream from the melting vessel 105 and coupled to the melting vessel 105 by a first connecting conduit 129. In some embodiments, molten material 121 can be gravity-fed from the melting vessel 105 to the fining vessel 127 by the first connecting conduit 129. For example, in some embodiments, gravity can drive the molten material 121 through an interior pathway of the first connecting conduit 129 from the melting vessel 105 to the fining vessel 127. Additionally, in some embodiments, bubbles can be removed from the molten material 121 within the fining vessel 127 by various techniques. [0051] In some embodiments, the glass manufacturing apparatus 100 can further comprise a second conditioning station comprising a mixing vessel 131 that can be located downstream from the fining vessel 127. The mixing vessel 131 can provide a homogenous composition of molten material 121, thereby reducing or eliminating inhomogeneity that may otherwise exist within the molten material 121 exiting the fining vessel 127. As shown, the fining vessel 127 can be coupled to the mixing vessel 131 by a second connecting conduit 135. In some embodiments, molten material 121 can be gravity-fed from the fining vessel 127 to the mixing vessel 131 by the second connecting conduit 135. For example, in some embodiments, gravity can drive the molten material 121 through an interior pathway of the second connecting conduit 135 from the fining vessel 127 to the mixing vessel 131.

[0052] Additionally, in some embodiments, the glass melting and delivery apparatus 102 can comprise a third conditioning station comprising a delivery vessel 133 that can be located downstream from the mixing vessel 131. In some embodiments, the delivery vessel 133 can condition the molten material 121 to be fed into an inlet conduit 141. For example, the delivery vessel 133 can function as an accumulator and/or flow controller to adjust and provide a consistent flow of molten material 121 to the inlet conduit 141. As shown, the mixing vessel 131 can be coupled to the delivery vessel 133 by a third connecting conduit 137. In some embodiments, molten material 121 can be gravity fed from the mixing vessel 131 to the delivery vessel 133 by the third connecting conduit 137. For example, in some embodiments, gravity can drive the molten material 121 through an interior pathway of the third connecting conduit 137 from the mixing vessel 131 to the delivery vessel 133. As further illustrated, in some embodiments, a delivery pipe 139 can be positioned to deliver molten material 121 from the delivery vessel 133 to the inlet conduit 141 of the forming vessel 140.

[0053] As mentioned previously, embodiments of the methods of processing a molten material throughout the disclosure can be used with various embodiments of forming vessels. As shown in FIG. 1, the forming vessel 140 can be provided as a fusion down-draw apparatus to fusion draw the molten material 121 off a bottom edge (e.g., root 145) of a forming wedge 169. For example, in some embodiments, the molten material 121 can be delivered from the inlet conduit 141 of the forming vessel 140. The molten material 121 can then be formed into the glass ribbon 103 that can be based on the structure of the forming vessel 140. For example, as shown, the molten material 121 can be drawn off the root 145 of the forming vessel 140 along a draw path extending in a draw direction 154 of the glass manufacturing apparatus 100. In some embodiments, edge directors 163, 164 can direct the molten material 121 off the forming vessel 140 and define a width “W” of the glass ribbon 103. In some embodiments, the width “W” of the glass ribbon 103 can extend between the first outer edge 153 of the glass ribbon 103 and the second outer edge 155 of the glass ribbon

103

[0054] In some embodiments, the width “W” of the glass ribbon 103 can be about 20 millimeters (mm) or more, about 50 mm or more, about 100 mm or more, about 500 mm or more, about 1,000 mm or more, about 2,000 mm or more, about 3,000 mm or more, about 4,000 mm or more, although other widths can be provided in further embodiments. As used herein, the width W is defined in a direction orthogonal to the draw direction 154. In some embodiments, the width “W” of the glass ribbon 103 can be in a range from about 20 mm to about 4,000 mm, from about 50 mm to about 4,000 mm, from about 100 mm to about 4,000 mm, from about 500 mm to about 4,000 mm, from about 1,000 mm to about 4,000 mm, from about 2,000 mm to about 4,000 mm, from about 3,000 mm to about 4,000 mm, from about 2,000 mm to about 3,000 mm, from about 50 mm to about 3,000 mm, from about 100 mm to about 3,000 mm, from about 500 mm to about 3,000 mm, from about 1,000 mm to about 3,000 mm, from about 2,000 mm to about 3,000 mm, from about 2,000 mm to about 2,500 mm, or any range and subrange therebetween.

[0055] In some embodiments, the forming vessel 140 can receive the molten material 121 from the inlet conduit 141. The forming vessel 140 can comprise the forming wedge 169 comprising a pair of downwardly-inclined converging surface portions extending between opposed ends 165, 166 of the forming wedge 169. The pair of downwardly-inclined converging surface portions of the forming wedge 169 can converge along the draw direction 154 to intersect along a bottom edge of the forming wedge 169 to define the root 145 of the forming vessel 140.

[0056] Additionally, in some embodiments, the molten material 121 in the forming vessel 140 overflows the forming vessel 140 by simultaneously flowing over weirs and downward over the outer surfaces of the weirs. Respective streams of molten material 121 flow along the corresponding downwardly-inclined converging surface portions of the forming wedge 169 to be drawn off the root 145 of the forming vessel 140, where the flows converge and fuse into the ribbon of molten material 121 that can be drawn off the root 145 along the draw direction 154 and cooled into the glass ribbon 103. In some embodiments, the glass ribbon 103 can traverse along draw direction 154 at about 1 millimeter per second (mm/s) or more, about 10 mm/s or more, about 50 mm/s or more, about 100 mm/s or more, or about 500 mm/s or more, for example, in a range from about 1 mm/s to about 500 mm/s, from about 10 mm/s to about 500 mm/s, from about 50 mm/s to about 500 mm/s, from about 100 mm/s to about 500 mm/s, or any range and subrange therebetween.

[0057] The glass ribbon 103 comprises a first major surface and a second major surface opposite the first major surface defining a thickness (e.g., average thickness) of the glass ribbon 103 therebetween. As used herein, unless otherwise noted, thickness is defined in a direction normal to a major surface. In some embodiments, the thickness of the glass ribbon 103 can be about 2 millimeters (mm) or less, about 1 mm or less, about 0.5 mm or less, about 300 micrometers (pm) or less, about 200 pm or less, about 100 pm, although other thicknesses may be provided in further embodiments. For example, in some embodiments, the thickness of the glass ribbon 103 can be in a range from about 50 pm to about 750 pm, from about 100 pm to about 700 pm, from about 200 pm to about 600 pm, from about 300 pm to about 500 pm, from about 50 pm to about 500 pm, from about 50 pm to about 700 pm, from about 50 pm to about 600 pm, from about 50 pm to about 500 pm, from about 50 pm to about 400 pm, from about 50 pm to about 300 pm, from about 50 pm to about 200 pm, from about 50 pm to about 100 pm, or any range and subrange therebetween.

[0058] In some embodiments, the glass separator 149 can then separate a separated glass ribbon 104 from the glass ribbon 103 along the separation path 151 as the glass ribbon 103 is formed by the forming vessel 140. As illustrated, in some embodiments, the separation path 151 can extend along the width “W” of the glass ribbon 103 between the first outer edge 153 and the second outer edge 155. Additionally, in some embodiments, the separation path 151 can extend perpendicular to the draw direction 154 of the glass ribbon 103. The separated glass ribbon 104 can then be processed into a device. For example, the separated glass ribbon can be used in a wide range of devices comprising liquid crystal displays (LCDs), electrophoretic displays (EPD), organic light emitting diode (OLED) displays, plasma display panels (PDPs), touch sensors, photovoltaics, appliances (e.g., stovetops), or the like.

[0059] As shown in FIGS. 1-2, the melting vessel 105 can comprise a ceramic body 173. In some embodiments, the ceramic body 173 can comprise a refractory material. In some embodiments, the ceramic body 173 can comprise one or more of zirconia (ZrO?), zircon (ZrSiCL), alumina (AI2O3), magnesium oxide (MgO), silicon carbide (SiC), silicon nitride (S13N4), silicon oxynitride, aluminum nitride, aluminum oxynitride, a SiAlON (a combination of alumina and silicon nitride and can have a chemical formula, for example, Si 12-m-nAlm+nOnN i6-n, SL-nAlnOnNs-n, or Sb-nAlnOi+iJNri-n, where m, n, and the resulting subscripts are all non-negative integers), titania (TiCh), hafnium oxide (FfoO), yttrium oxide (Y2O3), aluminum nitride (AIN), fused quartz, graphite, mullite (a mineral comprising a combination of aluminum oxide and silicon dioxide), or spinel (MgAhCL). In further embodiments, the ceramic body 173 can comprise a combination of zircon and an amorphous phase (e.g., glass) or zirconia and amorphous phase (e.g., glass). In further embodiments, the ceramic body 173 can comprise a plurality of crystal grains that may be at least partially (e.g., entirely) surrounded by an intergranular glass phase (e.g., an amorphous phase). In further embodiments, the intergranular glass phase may comprise silica. In some embodiments the ceramic body may comprise one or more of the above materials in a weight % of about 50% or more, about 70% or more, about 80% or more, about 99% or less, about 95% or less, or about 90% or less. In some embodiments the ceramic body may comprise one or more of the above materials in a weight % in a range from about 50% to about 99%, from about 50% to about 95%, from about 50% to about 90%, from about 70% to about 99%, from about 70% to about 95%, from about 70% to about 90%, from about 80% to about 90%, or any range or subrange therebetween. In further embodiments, the ceramic body may comprise zirconia within the above-mentioned ranges. In some embodiments, the ceramic body may be fusion- cast or sintered to form the melting vessel 105. In some embodiments, the melting vessel 105 may comprise a ceramic body 173 comprising a plurality of bricks.

[0060] The ceramic body 173 can comprise a surface 205, as shown in FIG. 1-2. In some embodiments, as shown, the surface 205 of the ceramic body 173 can define a containment region 175. In further embodiments, the containment region 175 can be configured to receive molten material 121, as shown. In even further embodiments, as shown in FIG. 1, the ceramic body 173 can comprise a melting vessel 105. In even further embodiments, as discussed above, the ceramic body can comprise a fining vessel, a mixing vessel, or a delivery vessel.

[0061] A coating 207 can be deposited on the surface 205 of the ceramic body 173, as shown in FIG. 2. In some embodiments, the coating 207 can comprise one or more alkali metals and/or alkali-earth metals. As used herein, alkali metals comprise lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). As sued herein alkali- earth metals comprise beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). Alkali metals and/or alkali-earth metals can be elemental, an ion, in an oxide compound, or in another compound. In some embodiments, the coating can comprise an alkali metal oxide. In further embodiments, the coating can comprise sodium oxide (Na₂0). As used herein a weight % on an oxide basis refers to the weight % if the component were in an oxide form even when the component is not actually in an oxide form. For example, a weight% on an oxide basis of sodium in NaiCCh refers to the weight % as if the sodium was in Na?0. In some embodiments, the coating 207 can comprise a total weight % on an oxide basis of alkali metal(s) and/or alkali-earth metal(s) of about 1.3% or more, about 2% or more, about 5% or more, about 10% or more, about 50% or less, about 30% or less, or about 20% or less. In some embodiments, the coating 207 can comprise a total weight % on an oxide basis of alkali metal(s) and/or alkali-earth metal(s) in a range from about 1.3% to about 50%, from about 1.3% to about 30%, from about 1.3% to about 20%, from about 2% to about 50%, from about 2% to about 30%, from about 2% to about 20%, from about 5% to about 50%, from about 5% to about 30%, from about 5% to about 20%, from about 10% to about 50%, from about 10% to about 30%, from about 10% to about 20%, or any range or subrange therebetween.

[0062] Further, in some embodiments, providing a coating comprising alkali metal and/or alkali-earth metal on the surface of a ceramic body can minimally impact the resistivity of the ceramic body. Without wishing to be bound by theory, an increase in a concentration of alkali metal and/or alkali-earth metal compounds can be associated with a decreased resistivity. In some embodiments, the ceramic body can be part of a resistive heating system, for example, a melting vessel where an electrical current flows through the molten material contained therein to increase a temperature of the molten material. A decrease in resistivity can be associated with problems, for example, a short circuit through the ceramic body bypassing the molten material and/or melting a portion of the ceramic body. Consequently, providing a coating containing alkali metal and/or alkali-earth metal can provide the technical benefit of minimizing a decrease in resistivity while decreasing contamination of the molten material by the ceramic body.

[0063] In some embodiments, the coating 207 can comprise one or more of silicon dioxide (S1O2), alumina (AI2O3), boric oxide (e.g., B2O3), and sodium oxide (Na20). In further embodiments, the coating 207 can comprise silica of about 30% or more, about 50% or more, about 70% or more, about 85% or less, about 80% or less, or about 70% or less as a weight % of oxides in the coating 207. In further embodiments, the coating 207 can comprise silica of about in a range from about 30% to about 85%, from about 30% to about 80%, from about 30% to about 70%, from about 50% to about 85%, from about 50% to about 80%, from about 50% to about 75%, from about 50% to about 70%, from about 70% to about 85%, from about 70% to about 80%, or any range or subrange therebetween in weight % of oxides in the coating 207. In further embodiments, the coating 207 can comprise alumina of 0% or more, about 5% or more, about 10% or more, about 30% or less, about 20% or less, or about 10% or less of oxides in the coating 207. In further embodiments, the coating 207 can comprise alumina in a range from 0% to about 30%, from 0% to about 20%, from 0% to about 10%, from about 5% to about 30%, from 5% to about 20%, from about 5% to about 10%, from about 10% to about 30%, from about 10% to about 20%, or any range or subrange therebetween in weight % of oxides in the coating 207. In further embodiments, the coating 207 can comprise boric oxide of 0% of more, about 2% or more, about 5% or more, about 10% or less, about 8% or less, or about 5% or less in weight % of oxides in the coating 207. In further embodiments, the coating 207 can comprise boric oxide in a range from 0% to about 10%, from 0% to about 8%, from 0% to about 5%, from about 2% to about 10%, from about 2% to about 8%, from about 2% to about 5%, from about 5% to about 10%, from about 5% to about 8%, or any range or subrange therebetween in weight % of oxides in the coating 207. In further embodiments, the coating 207 can comprise sodium oxide of about 1.3% or more, about 3% or more, 6.5% or more, about 8% or more, about 10% or more, about 13% or less, about 11% or less, or about 10% or less in weight % of oxides in the coating 207. In further embodiments, the coating 207 can comprise sodium oxide in a range from about 1.3% to about 13%, from about 1.3% to about 11%, from about 1.3% to about 11%, from about 3% to about 13%, from about 3% to about 11%, from about 6.5% to about 13%, from about 6.5% to about 11%, from about 6.5% to about 10%, from about 8% to about 13%, from about 8% to about 11%, from about 8% to about 10%, from about 10% to about 13%, from about 10% to about 11%, or any range or subrange therebetween in weight % of oxides in the coating 207. In further embodiments, the coating can comprise a combination of silicon dioxide (S1O₂), alumina (AI₂O₃), boric oxide (e.g., B₂O₃), and sodium oxide (Na₂0), where each oxide is within the weight% ranges discussed above.

[0064] In some embodiments, the coating 207 can comprise a particulate coating 507 as shown in FIG. 5. As used herein, a particulate coating comprises a plurality of solid particles deposited over a surface. For example, with reference to FIG. 5, The particulate coating 507 comprises solid particles deposited over the surface 205 of the ceramic body 173. In some embodiments a median size of the solid particles can be in a range from about 10 micrometers to about 15 micrometers. In some embodiments, a solid particle of the solid particles can comprise one or more of the oxides described above. In further embodiments, a solid particle of the solid particles can comprise alkali-containing glass frit. In even further embodiments, the glass frit can comprise silica and sodium oxide. In even further embodiments, the glass frit can comprise all the oxides present in the particulate coating 507. In some embodiments, the particulate coating 507 can comprise an average thickness of about 20 micrometers (pm) or more, about 50 pm or more, about 200 pm or more, about 2 millimeters (mm) or less, about 1 mm or less, or about 500 mih or less. In some embodiments, the particulate coating 507 can comprise an average thickness in a range from about 20 pm to about 2 mm, from about 20 pm to about 1 mm, from about 20 pm to about 500 pm, from about 50 pm to about 2 mm, from about 50 pm to about 1 mm, from about 50 pm to about 500 pm, from about 200 pm to about 2 mm, from about 200 pm to about 1 mm, from about 200 pm to about 500 pm, or any range or subrange therebetween. In some embodiments, a particulate coating 507 may be formed by depositing a slurry on the surface 205 of the ceramic body 173.

[0065] In some embodiments, the coating 207 can comprise a glass layer 209, as shown in FIG. 2. As used herein, a glass layer comprises a continuous layer comprising an amorphous phase that covers at least a portion of a surface. For example, with reference to FIG. 2, the glass 209 comprises a continuous surface comprising an amorphous phase that covers the surface 205 of the ceramic body 173. In further embodiments, the glass layer 209 can be formed by heating a particulate coating 507. In further embodiments, the glass layer 209 can comprise an average thickness within the ranges discussed above with regards to the particulate coating 507. Depositing a coating 207 (e.g., particulate coating 507, glass layer 209) can reduce contamination of the molten material 121 because less surface area of the surface 205 of the ceramic body 173 may be in contact with the molten material 121, which means that less of the material of the ceramic body 173 may corrode and travel with the molten material 121 as a contaminant than if the coating 207 was not applied. Additionally, suppressing corrosion of the ceramic body 173 can increase the lifetime of the melting vessel 105 and thus the entire glass manufacturing apparatus 100. The lifetime of the melting vessel 105 comprising the ceramic body 173 may be increased because it will take longer to breach a wall of the melting vessel 105 since the rate of loss of a wall of the melting vessel 105 due to corrosion may be decreased (e.g., reduced) when the coating 207 is applied.

[0066] In some embodiments, as discussed above, the ceramic body 173 can comprise a plurality of bricks. In further embodiments, the coating (e.g., slurry 407, particulate coating 507) can be deposited on one side of a brick. In even further embodiments, the bricks can be assembled so that a surface 205 of the ceramic body 173 has a coating deposited on it. In further embodiments, the coating (e.g., slurry 407, particulate coating 507) can be deposited on more than one side of a brick. In even further embodiments, the bricks may be heated to form a glass layer 209 on the brick before assembling the ceramic body 173. In further embodiments, bricks can be assembled to form the ceramic body 173 before heating the ceramic body to form a glass layer 209. [0067] Exemplary molten materials, which may be free of lithia or not, can comprise soda lime molten material, aluminosilicate molten material, alkali-aluminosilicate molten material, borosilicate molten material, alkali-borosilicate molten material, alkali- alumni ophosphosilicate molten material, or alkali-aluminoborosilicate glass molten material. In one or more embodiments, a molten material 121 may comprise, in mole percent (mol %): S1O2 in a range from about 40 mol % to about 80%, AI2O3 in a range from about 10 mol % to about 30 mol %, B2O3 in a range from about 0 mol % to about 10 mol %, ZrCE in a range from about 0 mol% to about 5 mol %, P2O5 in a range from about 0 mol % to about 15 mol %, Ti0₂ in a range from about 0 mol % to about 2 mol %, R2O in a range from about 0 mol % to about 20 mol %, and RO in a range from 0 mol % to about 15 mol %. As used herein, R2O can refer to an alkali metal oxide, for example, LEO, Na₂0, K2O, Rb₂0, and CS2O. As used herein, RO can refer to MgO, CaO, SrO, BaO, and ZnO. In some embodiments, a molten material 121 may optionally further comprise in a range from about 0 mol % to about 2 mol %, any one or more of Na₂S0₄, NaCl, NaF, NaBr, K2SO4, KC1, KF, KBr, AS2O3, Sb₂0₃, Sn02, Fe20₃, MnO, Mhq2, Mhq₃, Mh2q₃, MmCri, MU2O7. In some embodiments, the glass ribbon 103 and/or glass sheets formed from the molten material 121 may be transparent, meaning that the glass ribbon 103 drawn from the molten material 121 can comprise an average light transmission over the optical wavelengths from 400 nanometers (nm) to 700 nm of about 85% or greater, about 86% or greater, about 87% or greater, about 88% or greater, about 89% or greater, about 90% or greater, about 91% or greater, or about 92% or greater.

[0068] The glass manufacturing apparatus 100 of the embodiments of the disclosure can be used in methods of processing a molten material 121. Methods of processing a molten material can be discussed with reference to the flow chart in FIG. 6 and example method steps illustrated in FIGS. 3-5.

[0069] In some embodiments, a first step 601 can comprise providing a ceramic body 173. The ceramic body 173 can comprise the materials discussed above (e.g., zirconia). For example, in some embodiments, the ceramic body 173 can comprise zirconia within the ranges discussed above (e.g., in a range from about 50% to about 99% by weight of the ceramic body 173). In some embodiments, the ceramic body can comprise zirconia grains and a silica-containing intergranular glass phase.

[0070] In some embodiments, a second step 603 can comprise depositing a slurry 407 on the surface 205 of the ceramic body, as shown in FIG. 4. In some embodiments, the slurry 407 can comprise water, a thickening agent, sodium oxide, and silica. In further embodiments, the slurry 407 can comprise the composition discussed above with regards to the particulate coating 507 in addition to water and a thickening agent. In some embodiments, the thickening agent can comprise methyl cellulose, starch, pectin, collagen, carrageenan, agar, alginin, guar gum, locust bean gum, xanthan gum, and/or soy lecithin. Providing a thickening agent can increase the viscosity of the slurry so that the slurry remains in place after it is deposited onto the surface 205 to produce a particulate coating 507 with a predetermined thickness. In some embodiments, as shown in FIG. 4, the slurry 407 can be deposited on the surface 205 using a nozzle 403. The nozzle can disperse droplets 405 of the slurry 407 that can help regulate the amount of slurry deposited. In some embodiments, the slurry 407 can be deposited by spreading the slurry using a tool (e.g., brush), by pouring the slurry, or other conventional means.

[0071] In some embodiments, a third step 605 can comprise drying the slurry to form the particulate coating 507 as shown in FIG. 5. In some embodiments, after depositing the slurry 407, the slurry 407 can be dried for about 6 hours or more, about 12 hours or more, about 24 hours or more, about 168 hours or less, about 72 hours or less, or about 48 hours or less. In some embodiments, after depositing the slurry 407, the slurry 407 can be dried for a time in a range from about 6 hours to about 168 hours, from about 6 hours to about 72 hours, from about 6 hours to about 48 hours, from about 12 hours to about 168 hours, from about 12 hours to about 72 hours, from about 12 hours to about 48 hours, from about 24 hours to about 168 hours, from about 24 hours to about 72 hours, from about 24 hours to about 48 hours, or any range or subrange therebetween. As described above, in some embodiments, the particulate coating 507 can comprise a mixture of oxides within the weight % ranges described above (e.g., silica in a range from about 30% to about 85%, alumina in a range from 0% to about 30%, boric oxide in a range from 0% to about 10%, and sodium oxide in a range from about 1.3% to about 13%).

[0072] In some embodiments, a fourth step 607 can comprise heating the ceramic body 173 over time to increase a temperature of the ceramic body 173 from a first temperature to second temperature. As described above, the coating (e.g., particulate coating 507) can comprise alkali metal and/or alkali-earth metal within the ranges discussed above (e.g., in a range from about 1.3% to about 50% by weight on an oxide basis). The particulate coating 507 can form a glass layer 209 during the heating.

[0073] In some embodiments, the first temperature of the ceramic body 173 can be about 0°C or more, about 10°C or more, about 20°C or more, about 100°C or less, about 50°C or less, or about 30°C or less. In some embodiments, the first temperature of the ceramic body 173 can be in a range from about 0°C to about 100°C, from about 0°C to about 50°C, from about 0°C to about 30°C, from about 10°C to about 100°C, from about 10°C to about 50°C, from about 20°C to about 100°C, from about 20°C to about 50°C, from about 20°C to about 30°C, or any range or subrange therebetween. In further embodiments, the first temperature of the ceramic body 173 may be about room temperature.

[0074] In some embodiments, the second temperature of the ceramic body 173 can be about 1400°C or more, about 1500°C or more, about 1600°C or more, about 1700°C or less, about 1650°C or less, or about 1600°C or less. In some embodiments, the second temperature of the ceramic body 173 can be in a range from about 1400°C to about 1700°C, from about 1400°C to about 1650°C, from about 1400°C to about 1600°C, from about 1500°C to about 1700°C, from about 1500°C to about 1650°C, from about 1500°C to about 1600°C, from about 1600°C to about 1700°C, from about 1600°C to about 1650°C, or any range or subrange therebetween.

[0075] In some embodiments, a fifth step 609 can comprise contacting the glass layer 209 with the molten material 121. In some embodiments, as shown in FIG. 1, the molten material 121 can be contained within a containment region 175 defined by the surface 205 of the ceramic body 173. For example, in various embodiments, batch material may be heated in the containment region to form the molten material. In some embodiments, a sixth step 611 can comprise forming a glass article or a glass-ceramic article from the molten material 121.

[0076] In some embodiments, as shown in FIG. 6, methods can proceed from the first step through the fifth step sequentially 601, 603, 605, 607, and 609. In some embodiments, as shown, methods can comprise the step 613 of providing a ceramic body comprising a coating (e.g., particulate coating). Methods can then proceed through steps 607 and 609. In some embodiments, the method can complete after step 609. In some embodiments, methods may comprise forming a glass article or a glass-ceramic article from the molten material 121.

[0077] In some embodiments, as shown in FIG. 2, ions can diffuse from the coating 207 in a direction 203 into the ceramic body 173. In further embodiments, the ions can comprise one or more types of alkali ions and/or alkali-earth ions. In even further embodiments, the ions can comprise sodium ions. In further embodiments, as shown, the coating 207 can comprise a glass layer 209. In further embodiments, ions diffusing from the coating 207 (e.g., glass layer 209) into the ceramic body 173 can increase a concentration of alkali metal and/or alkali-earth metal between the surface 205 and about 900 pm from the surface 205 in a bulk of the ceramic body 173 from a first concentration to a second concentration while the ceramic body 173 is heated. In some embodiments, the first concentration may be a trace (e.g., impurity, residual) level. In some embodiments, the first concentration by weight on an oxide basis can be about 1.3% or less, about 1% or less, about 0.7% or less, about 0.07% or more, about 0.1% or more, or about 0.5% or more. In some embodiments the first concentration by weight on an oxide basis may be in a range from about 0.07% to about 1.3%, from about 0.07% to about 1%, from about 0.07% to about 0.7%, from about 0.1% to about 1.3%, form about 0.1% to about 1%, from about 0.1% to about 0.7%, from about 0.5% to about 1.3%, from about 0.5% to about 1%, from about 0.5% to about 0.7%, or any range or subrange therebetween. In some embodiments, the second concentration by weight on an oxide basis can be greater than the first concentration by weight by about 0.1% or more, about 0.3% or more, about 0.5% or more, about 3% or less, about 2% or less, or about 1% or less. In some embodiments, the second concentration by weight on an oxide basis can be greater than the first concentration by weight in a range from about 0.1% to about 3%, from about 0.3% to about 3%, from about 0.5% to about 3%, from about 0.1% to about 2%, from about 0.3% to about 2%, from about 0.5% to about 2%, from about 0.1% to about 1%, from about 0.3% to about 1%, from about 0.5% to about 1%, or any range or subrange therebetween. In some embodiments, the second concentration by weight on an oxide basis can be about 1.5% or more, about 1.7% or more, about 2% or more, about 3% or less, about 2.5% or less, or about 2% or less. In some embodiments, the second concentration by weight on an oxide basis can be in a range from about 1.5% to about 3%, from about 1.5% to about 2.5%, from about 1.5% to about 2%, from about 1.7% to about 3%, from about 1.7% to about 2.5%, from about 1.7% to about 2%, from about 2% to about 3%, from about 2% to about 2.5%, or any range or subrange therebetween.

[0078] Suppressing phase transformations, crystal grain formation, and/or crystal grain growth (e.g., zircon formation) within the ceramic body 173 while heating the ceramic body 173 provides the technical benefits of decreased likelihood of cracking the ceramic body 173 during heating and faster heating of the ceramic body 173. Without wishing to be bound by theory, phase transformations, crystal grain growth, and/or crystal grain formation can be associated with changes in volume. Thus, a coating comprising alkali metal and/or alkali-earth metal (e.g., in a range from about 1.3% to about 50% by weight on an oxide basis), phase transformations, crystal grain formation, and/or crystal grain growth during heating of the ceramic body 173 can be associated with cracking of the ceramic body 173 because of the volume changes associated with phase transformation, crystal grain formation, and/or crystal grain growth that can occur unevenly throughout the material. However, in some embodiments, the coating can decrease (e.g., reduce, prevent) cracking of the ceramic body 173 during heating by suppressing phase transformations, crystal grain formation, and/or crystal grain growth. In some embodiments, the ceramic body 173 can be heated faster when the coating comprising alkali metal and/or alkali-metals is deposited on the surface 205 of the ceramic body 173 because the risk of cracking of the ceramic body 173 may be decreased.

[0079] Suppressing corrosion of the ceramic body 173 provides the technical benefits of decreased contamination of the molten material 121 and a longer lifetime for the melting vessel 105 comprising the ceramic body 173. Decreased corrosion of the ceramic body 173 through the application of the coating 207 can reduce contamination of the molten material 121 because, for example, less of a surface area of the surface 205 of the ceramic body 173 may be in contact with the molten material 121, which means that less of the material of the ceramic body 173 may corrode and/or travel with the molten material 121 as a contaminant than if the coating 207 was not applied. Additionally, suppressing corrosion of the ceramic body 173 can increase the lifetime of the melting vessel 105 and thus the entire glass manufacturing apparatus 100. The lifetime of the melting vessel 105 comprising the ceramic body 173 may be increased because it will take longer to breach a wall of the melting vessel 105 since the rate of loss of a wall of the melting vessel 105 due to corrosion may be decreased (e.g., reduced) when the coating 207 is applied.

[0080] EXAMPLES

[0081] Various embodiments will be further clarified by the following examples. FIGS. 7-9 demonstrate the ability of alkali metal and/or alkali-metal ions to decrease zircon formation by comparing examples of zirconia ceramic bodies with a range of sodium concentrations. FIGS. 10-11 demonstrate the decreasing zircon formation depth and zircon weight, respectively, as a concentration of sodium is increased, in accordance with embodiments of the disclosure. Although these examples use sodium as the alkali metal and/or alkali-earth metal, it is to be understood that similar trends are expected for other alkali metals and alkali-earth metals.

[0082] FIG. 7 is a schematic representation of an image from a scanning electron microscope (SEM) for a zirconia sample of a ceramic body at 1400°C comprising less than 0.01 weight % (% wt) sodium (Na). In FIG. 7, large zirconia grains 703 are shown surrounded by an amorphous phase 701 (e.g., interstitial glass) with large zircon grains 705. Although not shown, larger scale (e.g., millimeter scale) images of the zirconia sample of FIG. 7 showed extensive cracking within the sample.

[0083] FIG. 8 is a schematic representation of an image from a SEM for a zirconia sample of a ceramic body at 1400°C comprising 0.1% wt Na. In FIG. 8, zirconia grains 803 are shown surrounded by an amorphous phase 801 (e.g., interstitial glass phase) with zircon grains 805. The zircon grains 805 in FIG. 8 are smaller than the large zircon grains 705 in FIG. 7. This demonstrates that 0.1 w% alkali-metal ion (e.g., Na ion) is sufficient to begin suppressing the formation of zircon within a zirconia ceramic body. Although not shown, larger scale (e.g., millimeter scale) images of the zirconia sample of FIG. 8 showed some cracking that was less than the extensive cracking and formation of pores observed with the larger scale (e.g., millimeter scale) images of the zirconia sample of FIG. 7. As such, a decrease in zircon content and/or zircon grain size is associated with reduced cracking and/or pore formation in zirconia samples.

[0084] FIG. 9 is a schematic representation of an image from a SEM for a zirconia sample of a ceramic body at 1400°C comprising 0.2% wt Na. In FIG. 9, only zirconia grains 903 and an amorphous phase 901 are visible. In FIG. 9, no zircon is visible, demonstrating that 0.2% wt alkali-metal ion is sufficient to suppress zircon formation and further to eliminate zircon formation within a zirconia ceramic body. Although not shown, larger scale (e.g., millimeter scale) images of the zirconia sample of FIG. 9 did not show any extended crack formation. As such, eliminating zircon from a zirconia sample is associated with a further reduction in cracking and/or pore formation, as compared to merely decreasing zircon content and/or grain size without eliminating zircon entirely.

[0085] FIG. 10 is a plot illustrating zircon-forming depth as a function of sodium concentration based on experimental results. The horizonal axis 1001 (e.g., x-axis) is a sodium concentration in weight % on an oxide basis. With regards to FIG. 10, the sodium concentration is average weight % of sodium in a silica-containing intergranular glass phase between the surface 205 of the ceramic body and about 900 pm from the surface 205 in a bulk of the ceramic body 173. The vertical axis 1003 (e.g., y-axis) is a zircon-forming depth in micrometers (pm). As used herein, the zircon-forming depth to which zircon can form is based on analysis of SEM images of the samples with the corresponding sodium concentration. The zircon-forming depth is shown as extending from 0 pm to a corresponding maximum depth to indicate that zircon can form within that range. Samples were prepared by coating the zirconia ceramic body with a slurry. The slurry was generated by mixing a powder with 2% wt (of the powder) of methyl cellulose and water to obtain the desired viscosity. The powder comprised 62% wt silica, 20% wt alumina, 4% wt boric oxide, and a mixture of sodium-containing glass to obtain the predetermined sodium concentration with additional silica comprising the balance. The coated ceramic body was dried for 24 hours at room temperature before it was heated in a furnace at 1550°C for 7 days. The samples were then analyzed to determine the sodium concentration and the zircon-forming depth.

[0086] In FIG. 10, the first sample 1005 was generated by applying a sodium-free (e.g., 0% sodium) coating to the zirconia-containing ceramic body. For the first sample 1005, the measured zircon-forming depth was about 1700 pm and the sodium concentration was about 0.2% wt. The second sample 1007 was a zirconia-containing ceramic body without any coating applied. For the second sample 1007, the measured zircon-forming depth was about 600 pm and the sodium concentration was about 1.3% wt on an oxide basis. This demonstrates that application of a sodium-free coating (e.g., first sample 1005) can decrease the sodium concentration in the ceramic body (e.g., via diffusion of sodium from the ceramic body into the coating), which is associated with increased zircon formation (e.g., increased cracking). For this ceramic body, the intrinsic sodium concentration at the surface is about 1.3% wt on an oxide basis. To decrease the zircon-forming depth relative to the second sample 1007, the coating should comprise a sodium concentration greater than 1.3% wt or more on an oxide basis. Other ceramic bodies can contain different intrinsic amount of sodium and the amount of sodium in the coating needed to decrease the zircon-forming depth will also vary.

[0087] In FIG. 10, the third sample 1009 was generated by applying a coating comprising 6.5% wt sodium oxide. For the third sample 1009, the measured zircon-forming depth was about 300 pm and the sodium concentration was about 2% wt on an oxide basis. The fourth sample 1011 was generated by applying a coating comprising 13% wt sodium oxide. For the fourth sample 1011, the measured zircon-forming depth was 0 pm and the sodium concentration was about 2.9% wt. This demonstrates that increasing the sodium concentration in the coating (e.g., 6.5% wt sodium oxide, 13% wt sodium oxide) above the intrinsic concentration of sodium in the ceramic body (e.g., silica-containing intergranular glass phase) is associated with a decrease in the zircon-forming depth. Without wishing to be bound by theory, it is believed that sodium or other alkali metals can remove already-formed zircon in zirconia-containing ceramic bodies in addition to preventing additional zircon formation. Further increasing the sodium concentration (e.g., 13% wt sodium oxide) led to complete prevention and/or elimination of zircon.

[0088] FIG. 11 is a plot illustrating zircon formation as a function of intergranular sodium concentration based on simulation results. The horizonal axis 1101 (e.g., x-axis) is a sodium concentration in weight % on an oxide basis of the intergranular glass phase. The intergranular glass phase was modeled as comprising about 79% wt silica, about 9% wt alumina, about 8% wt boric oxide, and the corresponding amount of sodium oxide with additional silica comprising the balance. The vertical axis 1103 (e.g., y-axis) is a normalized zircon formation percentage. As shown, the reference for the vertical axis 1103 is for a sample comprising 0% sodium (or other alkali metal or alkali-earth metals) in the intergranular glass phase. As the concentration of sodium oxide in the intergranular glass phase increases from 0% to about 2%, the amount of zircon formed decreases. For example, about 0.5% wt sodium in the intergranular glass phase is associated with a normalized zircon formation of about 75%. Likewise, about 1% wt sodium oxide in the intergranular glass phase is association with a normalized zircon formation of about 45 %. Additionally, about 1.5% wt sodium oxide in the intergranular glass phase is associated with a normalized zircon formation of about 20%. Above about 2% wt sodium oxide in the intergranular glass phase, no zircon formation was observed. This demonstrates that increasing the concentration of sodium oxide in the intergranular glass phase from a first concentration of less than about 2% to a second concentration greater than the first concentration is associated with decreased zircon formation (e.g., decreased zircon formation). When the second concentration is about 2% or more, zircon formation may be entirely prevented (e.g., eliminated) based on these results.

[0089] As used herein, the terms “the,” “a,” or “an,” mean “at least one,” and should not be limited to “only one” unless explicitly indicated to the contrary. Thus, for example, reference to “a component” comprises embodiments having two or more such components unless the context clearly indicates otherwise.

[0090] As used herein, the term “about” means that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and/or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art. When the term “about” is used in describing a value or an endpoint of a range, the disclosure should be understood to comprise the specific value or endpoint referred to. If a numerical value or endpoint of a range in the specification recites “about,” the numerical value or endpoint of a range is intended to comprise two embodiments: one modified by “about,” and one not modified by “about.” It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint and independently of the other endpoint.

[0091] The terms “substantial,” “substantially,” and variations thereof as used herein are intended to note that a described feature is equal or approximately equal to a value or description. For example, a “substantially planar” surface is intended to denote a surface that is planar or approximately planar. Moreover, as defined above, “substantially similar” is intended to denote that two values are equal or approximately equal. In some embodiments, “substantially similar” may denote values within about 10% of each other, for example within about 5% of each other, or within about 2% of each other.

[0092] As used herein, the terms “comprising” and “including,” and variations thereof, shall be construed as synonymous and open ended, unless otherwise indicated. A list of elements following the transitional phrases comprising or including is a non-exclusive list, such that elements in addition to those specifically recited in the list may also be present.

[0093] While various embodiments have been described in detail with respect to certain illustrative and specific embodiments thereof, the present disclosure should not be considered limited to such, as numerous modifications and combinations of the disclosed features are possible without departing from the scope of the following claims.

Claims

What is claimed is:

1. A glass manufacturing apparatus comprising: a ceramic body comprising a surface; and a coating comprising an alkali metal or an alkali-earth metal in a range from about 1.3% to about 50% by weight on an oxide basis deposited on the surface.

2. The glass manufacturing apparatus of claim 1, wherein the ceramic body comprises zirconia.

3. The glass manufacturing apparatus of claim 2, wherein the zirconia is in a range from about 50% to about 99% by weight of the ceramic body.

4. The glass manufacturing apparatus of any one of claims 2-3, wherein the zirconia comprises zirconia grains and the ceramic body further comprises an intergranular glass phase.

5. The glass manufacturing apparatus of claim 1, wherein the coating comprises the following oxides in weight %:

Si0₂ 30 - 85,

AI2O3 0 - 30,

B2O3 0 - 10, and Na₂0 6.5 - 13, wherein the alkali metal or the alkali-earth metal comprises Na₂0.

6. The glass manufacturing apparatus of claim 1, wherein the coating comprises a particulate coating.

7. The glass manufacturing apparatus of claim 6, wherein the particulate coating comprises particles comprising a median particle size in a range from about 5 micrometers to about 15 micrometers.

8. The glass manufacturing apparatus of claim 1, wherein the coating comprises a glass layer.

9. The glass manufacturing apparatus of claim 1, wherein the surface of the ceramic body defines a containment region.

10. The glass manufacturing apparatus of claim 1, wherein the ceramic body comprises a melting vessel.

11. A method of processing a molten material : heating a ceramic body from a first temperature in a range from about 0°C to about 100°C to a second temperature in a range from about 1400°C to about 1700°C, the ceramic body comprising a surface and a particulate coating deposited on the surface comprising an alkali metal or an alkali-earth metal in a range from about 1.3% to about 50% by weight on an oxide basis, the particulate coating forming a glass layer during the heating; and contacting the glass layer with the molten material.

12. The method of claim 11, wherein, prior to the heating the ceramic body, further comprising depositing the particulate coating by depositing a slurry comprising water, a thickening agent, sodium oxide, and silica on the ceramic body.

13. The method of claim 12, wherein the thickening agent comprises methyl cellulose.

14. The method of any one of claims 12-13, wherein, after the depositing the slurry, further comprising drying the slurry from about 6 hours to about 168 hours to form the particulate coating before the heating the ceramic body.

15. The method of claim 11, wherein the particulate coating comprises the following oxides in weight %:

Si0₂ 30 - 85,

AI2O3 0 - 30,

16. The method of claim 11, wherein the particulate coating comprises particles comprising a median particle size in a range from about 5 micrometers to about 15 micrometers.

17. The method of claim 11, wherein the ceramic body comprises zirconia.

18. The method of claim 17, wherein the zirconia is in a range from about 50% to about 99% by weight of the ceramic body.

19. The method of any one of claims 17-18, wherein the zirconia comprises zirconia grains and the ceramic body further comprises an intergranular glass phase.

20. The method of claim 19, wherein a concentration of alkali metal or alkali-earth metal in the intergranular glass phase between the surface and 900 micrometers from the surface in a bulk of the ceramic body increases from a first concentration to a second concentration while the ceramic body is heated.

21. The method of claim 20, wherein the first concentration is about 1.3% or less by weight on an oxide basis.

22. The method of claim 20, wherein the second concentration is in a range from about 1.5% to about 3% by weight on an oxide basis.

23. The method of claim 11, wherein the molten material is contained within a containment region defined by the surface of the ceramic body.

24. The method of claim 11, further comprising forming a glass article or a glass-ceramic article from the molten material.