WO2020123226A1

WO2020123226A1 - Glass sheets with improved edge strength and methods of producing the same

Info

Publication number: WO2020123226A1
Application number: PCT/US2019/064430
Authority: WO
Inventors: Kaveh Adib; Robert Alan Bellman; Ya-Huei Chang; Jiangwei Feng; James Joseph Price
Original assignee: Corning Incorporated
Priority date: 2018-12-13
Filing date: 2019-12-04
Publication date: 2020-06-18

Abstract

A method of manufacturing and treating a glass article wherein the treatment of the article includes directing a flow of plasma, such as a flow of plasma comprising an atmospheric pressure plasma jet comprising at least one high thermal conductivity component, toward an edge surface of the article. Such treatment can increase the edge strength of the article. Such treatment can also increase the edge impact strength of the article. Such treatment can further reduce a density of particles on an edge surface of the article.

Description

GLASS SHEETS WITH IMPROVED EDGE STRENGTH AND METHODS OF

PRODUCING THE SAME

[0001] This application claims the benefit of priority under 35 U.S.C. § 119 of U.S.

Provisional Application Serial No. 62/778, 984 filed on December 13, 2018, the content of which is relied upon and incorporated herein by reference in its entirety.

Field

[0002] The present disclosure relates generally to glass sheets with improved edge quality and methods for producing the same and more particularly to glass sheets with greater edge strength and methods for producing the same.

Background

[0003] In the production of glass articles, such as glass sheets for display applications, including televisions and hand held devices, such as telephones and tablets, there are typically multiple processing steps that can involve glass particle generation, such as when glass sheets are separated from a glass ribbon as well as when the glass sheets are subject to finishing processes, such as edge grinding and polishing. Such processing steps, can also introduce surface flaws and defects along edges of the glass articles. Such flaws and defects can, among other things, adversely affect the mechanical strength and failure resistance of the glass articles. Given that there is a trend for thinner displays, it is desirable to produce thin glass articles, such as glass sheets, having sufficient mechanical failure resistance. Given that there is also a trend for higher resolution displays, it also is desirable to minimize the amount of particles present on such articles.

SUMMARY

[0004] Embodiments disclosed herein include a method for manufacturing a glass article. The method includes forming the glass article, wherein the glass article includes a first major surface, a second major surface parallel to the first major surface, and an edge surface extending between the first major surface and the second major surface in a perpendicular direction to the first and second major surfaces. A distance of the extension direction of the edge between the first and second major surfaces is less than or equal to about 0.5 millimeters. The method also includes directing a flow of plasma toward the edge surface. The plasma includes at least one high thermal conductivity component. An edge strength of the glass article subsequent to directing a flow of plasma toward the edge surface, as measured by the four point bend test, is at least about 250 MPa.

[0005] Embodiments disclosed herein also include a method for treating a glass article.

The glass article includes a first major surface, a second major surface parallel to the first major surface, and an edge surface extending between the first major surface and the second major surface in a perpendicular direction to the first and second major surfaces. A distance of the extension direction of the edge between the first and second major surfaces is less than or equal to about 0.5 millimeters. The method also includes directing a flow of plasma toward the edge surface. The plasma includes at least one high thermal conductivity component. An edge strength of the glass article subsequent to directing a flow of plasma toward the edge surface, as measured by the four point bend test, is at least about 250 MPa.

[0006] Embodiments disclosed herein also include a glass article. The glass article includes a first major surface, a second major surface parallel to the first major surface, and an edge surface extending between the first major surface and the second major surface in a perpendicular direction to the first and second major surfaces. A distance of the extension direction of the edge between the first and second major surfaces is less than or equal to about 0.5 millimeters. An edge strength of the glass article, as measured by the four point bend test, is at least about 250 MPa.

[0007] Additional features and advantages of the embodiments disclosed herein 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 disclosed embodiments as described herein, including the detailed description which follows, the claims, as well as the appended drawings.

[0008] 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 claimed embodiments. 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 serve to explain the principles and operations thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is a schematic view of an example fusion down draw glass making apparatus and process;

[0010] FIG. 2 is a schematic side view of a stage of an example glass sheet separation process;

[0011] FIG. 3 is a schematic side view of another stage of an example glass sheet separation process;

[0012] FIG. 4 is a schematic side view of yet another stage of an example glass sheet separation process;

[0013] FIG. 5 is a schematic side view of still yet another stage of an example glass sheet separation process;

[0014] FIG. 6 is an perspective view of a glass sheet;

[0015] FIG. 7 is a perspective view of at least a portion of a beveling process of an edge surface of a glass sheet;

[0016] FIG. 8 is a perspective view of at least a portion of an edge treatment process with a plasma jet;

[0017] FIGS. 9A and 9B are, respectively, charts showing edge strength and edge impact strength of glass samples tested according to methods disclosed herein;

[0018] FIG. 10 is a chart showing edge strength of glass samples tested according to methods disclosed herein;

[0019] FIGS. 11A and 1 IB are, respectively, charts showing edge strength and edge impact strength of glass samples tested according to methods disclosed herein; and

[0020] FIG. 12 is a chart showing edge strength of glass samples tested according to methods disclosed herein.

DETAILED DESCRIPTION

[0021] Reference will now be made in detail to the present preferred embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings.

Whenever possible, the same reference numerals will be 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.

[0022] Ranges can be expressed herein as from“about” one particular value, and/or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, for example by use of the antecedent“about,” it will be understood that the particular value forms another embodiment 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.

[0023] Directional terms as used herein - for example up, down, right, left, front, back, top, bottom - are made only with reference to the figures as drawn and are not intended to imply absolute orientation.

[0024] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order, nor that with any apparatus specific orientations be required. Accordingly, where a method claim does not actually recite an order to be followed by its steps, or that any apparatus claim does not actually recite an order or orientation to individual components, or it is not otherwise specifically stated in the claims or description that the steps are to be limited to a specific order, or that a specific order or orientation to components of an apparatus is not recited, it is in no way intended that an order or orientation be inferred, in any respect. This holds for any possible non-express basis for interpretation, including: matters of logic with respect to arrangement of steps, operational flow, order of components, or orientation of components; plain meaning derived from grammatical organization or punctuation, and; the number or type of embodiments described in the specification.

[0025] As used herein, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to“a” component includes aspects having two or more such components, unless the context clearly indicates otherwise.

[0026] As used herein, the term“high thermal conductivity component” refers to a component having a thermal conductivity at 25°C of at least 0.1 W/m-K.

[0027] As used herein, the term“plasma” refers to an electrically neutral ionized gas comprising positive ions and unbound electrons.

[0028] As used herein, the term“atmospheric pressure plasma jet” refers to a flow of plasma discharged from an aperture, wherein the plasma pressure approximately matches that of the surrounding atmosphere, including conditions wherein the plasma pressure is between 90% and 110% of 101.325 kilopascals (standard atmospheric pressure).

[0029] As used herein, the term“particles” refers to any type of particles that can be present on a surface, such as glass particles and dust particles. [0030] As used herein, the term“edge strength, as measured by the four point bend test”, refers to edge strength at which 10% of samples would be expected to fail using the glass flexure fixture four point test set forth in Suresh T. Gulati and John D. Helfinstine,“Edge Strength Testing of Thin Glasses”, International Journal of Applied Glass Science 2 [1] 39— 46 (2011).

[0031] As used herein, the term“two point bend test” refers to the edge strength test method set forth in Suresh T. Gulati, Jamie Westbrook, Stephen Carley, Hemanth Vepakomma and Toshihiko Ono,“45.2: Two point bending of thin glass substrates”, SID Conf, 652-654 (201 1)

[0032] As used herein, the term“edge impact strength, as measured by the pendulum drop test”, refers to the greatest height at which a 172 gram pendulum can be dropped on an edge of a glass sample with an observed impact diameter of less than 1 millimeter.

[0033] Shown in FIG. 1 is an exemplary glass manufacturing apparatus 10. In some examples, the glass manufacturing apparatus 10 can comprise a glass melting furnace 12 that can include a melting vessel 14. In addition to melting vessel 14, glass melting furnace 12 can optionally include one or more additional components such as heating elements (e.g., combustion burners or electrodes) that heat raw materials and convert the raw materials into molten glass. In further examples, glass melting furnace 12 may include thermal management devices (e g., insulation components) that reduce heat lost from a vicinity of the melting vessel. In still further examples, glass melting furnace 12 may include electronic devices and/or electromechanical devices that facilitate melting of the raw materials into a glass melt. Still further, glass melting furnace 12 may include support structures (e.g., support chassis, support member, etc.) or other components.

[0034] Glass melting vessel 14 is typically comprised of refractory material, such as a refractory ceramic material, for example a refractory ceramic material comprising alumina or zirconia. In some examples glass melting vessel 14 may be constructed from refractory ceramic bricks. Specific embodiments of glass melting vessel 14 will be described in more detail below.

[0035] In some examples, the glass melting furnace may be incorporated as a component of a glass manufacturing apparatus to fabricate a glass substrate, for example a glass ribbon of a continuous length. In some examples, the glass melting furnace of the disclosure may be incorporated as a component of a glass manufacturing apparatus comprising a slot draw apparatus, a float bath apparatus, a down-draw apparatus such as a fusion process, an up- draw apparatus, a press-rolling apparatus, a tube drawing apparatus or any other glass manufacturing apparatus that would benefit from the aspects disclosed herein. By way of example, FIG. 1 schematically illustrates glass melting furnace 12 as a component of a fusion down-draw glass manufacturing apparatus 10 for fusion drawing a glass ribbon for subsequent processing into individual glass sheets.

[0036] The glass manufacturing apparatus 10 (e.g., fusion down-draw apparatus 10) can optionally include an upstream glass manufacturing apparatus 16 that is positioned upstream relative to glass melting vessel 14. In some examples, a portion of, or the entire upstream glass manufacturing apparatus 16, may be incorporated as part of the glass melting furnace 12

[0037] As shown in the illustrated example, the upstream glass manufacturing apparatus 16 can include a storage bin 18, a raw material delivery device 20 and a motor 22 connected to the raw material delivery device. Storage bin 18 may be configured to store a quantity of raw materials 24 that can be fed into melting vessel 14 of glass melting furnace 12, as indicated by arrow 26. Raw materials 24 typically comprise one or more glass forming metal oxides and one or more modifying agents. In some examples, raw material delivery device 20 can be powered by motor 22 such that raw material delivery device 20 delivers a predetermined amount of raw materials 24 from the storage bin 18 to melting vessel 14. In further examples, motor 22 can power raw material delivery device 20 to introduce raw materials 24 at a controlled rate based on a level of molten glass sensed downstream from melting vessel 14. Raw materials 24 within melting vessel 14 can thereafter be heated to form molten glass 28.

[0038] Glass manufacturing apparatus 10 can also optionally include a downstream glass manufacturing apparatus 30 positioned downstream relative to glass melting furnace 12. In some examples, a portion of downstream glass manufacturing apparatus 30 may be incorporated as part of glass melting furnace 12. In some instances, first connecting conduit 32 discussed below, or other portions of the downstream glass manufacturing apparatus 30, may be incorporated as part of glass melting furnace 12. Elements of the downstream glass manufacturing apparatus, including first connecting conduit 32, may be formed from a precious metal. Suitable precious metals include platinum group metals selected from the group of metals consisting of platinum, iridium, rhodium, osmium, ruthenium and palladium, or alloys thereof. For example, downstream components of the glass manufacturing apparatus may be formed from a platinum -rhodium alloy including from about 70 to about 90% by weight platinum and about 10% to about 30% by weight rhodium. However, other suitable metals can include molybdenum, palladium, rhenium, tantalum, titanium, tungsten and alloys thereof.

[0039] Downstream glass manufacturing apparatus 30 can include a first conditioning (i.e., processing) vessel, such as fining vessel 34, located downstream from melting vessel 14 and coupled to melting vessel 14 by way of the above-referenced first connecting conduit 32. In some examples, molten glass 28 may be gravity fed from melting vessel 14 to fining vessel 34 by way of first connecting conduit 32. For instance, gravity may cause molten glass 28 to pass through an interior pathway of first connecting conduit 32 from melting vessel 14 to fining vessel 34. It should be understood, however, that other conditioning vessels may be positioned downstream of melting vessel 14, for example between melting vessel 14 and fining vessel 34. In some embodiments, a conditioning vessel may be employed between the melting vessel and the fining vessel wherein molten glass from a primary melting vessel is further heated to continue the melting process, or cooled to a temperature lower than the temperature of the molten glass in the melting vessel before entering the fining vessel.

[0040] Bubbles may be removed from molten glass 28 within fining vessel 34 by various techniques. For example, raw materials 24 may include multivalent compounds (i.e. fining agents) such as tin oxide that, when heated, undergo a chemical reduction reaction and release oxygen. Other suitable fining agents include without limitation arsenic, antimony, iron and cerium. Fining vessel 34 is heated to a temperature greater than the melting vessel temperature, thereby heating the molten glass and the fining agent. Oxygen bubbles produced by the temperature-induced chemical reduction of the fining agent(s) rise through the molten glass within the fining vessel, wherein gases in the molten glass produced in the melting furnace can diffuse or coalesce into the oxygen bubbles produced by the fining agent. The enlarged gas bubbles can then rise to a free surface of the molten glass in the fining vessel and thereafter be vented out of the fining vessel. The oxygen bubbles can further induce mechanical mixing of the molten glass in the fining vessel.

[0041] Downstream glass manufacturing apparatus 30 can further include another conditioning vessel such as a mixing vessel 36 for mixing the molten glass. Mixing vessel 36 may be located downstream from the fining vessel 34. Mixing vessel 36 can be used to provide a homogenous glass melt composition, thereby reducing cords of chemical or thermal inhomogeneity that may otherwise exist within the fined molten glass exiting the fining vessel. As shown, fining vessel 34 may be coupled to mixing vessel 36 by way of a second connecting conduit 38. In some examples, molten glass 28 may be gravity fed from the fining vessel 34 to mixing vessel 36 by way of second connecting conduit 38. For instance, gravity may cause molten glass 28 to pass through an interior pathway of second connecting conduit 38 from fining vessel 34 to mixing vessel 36. It should be noted that while mixing vessel 36 is shown downstream of fining vessel 34, mixing vessel 36 may be positioned upstream from fining vessel 34. In some embodiments, downstream glass manufacturing apparatus 30 may include multiple mixing vessels, for example a mixing vessel upstream from fining vessel 34 and a mixing vessel downstream from fining vessel 34. These multiple mixing vessels may be of the same design, or they may be of different designs.

[0042] Downstream glass manufacturing apparatus 30 can further include another conditioning vessel such as delivery vessel 40 that may be located downstream from mixing vessel 36. Delivery vessel 40 may condition molten glass 28 to be fed into a downstream forming device. For instance, delivery vessel 40 can act as an accumulator and/or flow controller to adjust and/or provide a consistent flow of molten glass 28 to forming body 42 by way of exit conduit 44. As shown, mixing vessel 36 may be coupled to delivery vessel 40 by way of third connecting conduit 46. In some examples, molten glass 28 may be gravity fed from mixing vessel 36 to delivery vessel 40 by way of third connecting conduit 46. For instance, gravity may drive molten glass 28 through an interior pathway of third connecting conduit 46 from mixing vessel 36 to delivery vessel 40.

[0043] Downstream glass manufacturing apparatus 30 can further include forming apparatus 48 comprising the above-referenced forming body 42 and inlet conduit 50. Exit conduit 44 can be positioned to deliver molten glass 28 from delivery vessel 40 to inlet conduit 50 of forming apparatus 48. For example in examples, exit conduit 44 may be nested within and spaced apart from an inner surface of inlet conduit 50, thereby providing a free surface of molten glass positioned between the outer surface of exit conduit 44 and the inner surface of inlet conduit 50. Forming body 42 in a fusion down draw glass making apparatus can comprise a trough 52 positioned in an upper surface of the forming body and converging forming surfaces 54 that converge in a draw direction along a bottom edge 56 of the forming body. Molten glass delivered to the forming body trough via delivery vessel 40, exit conduit 44 and inlet conduit 50 overflows side walls of the trough and descends along the converging forming surfaces 54 as separate flows of molten glass. The separate flows of molten glass join below and along bottom edge 56 to produce a single ribbon of glass 58 that is drawn in a draw or flow direction 60 from bottom edge 56 by applying tension to the glass ribbon, such as by gravity, edge rolls 72 and pulling rolls 82, to control the dimensions of the glass ribbon as the glass cools and a viscosity of the glass increases. Accordingly, glass ribbon 58 goes through a visco-elastic transition and acquires mechanical properties that give the glass ribbon 58 stable dimensional characteristics. Glass ribbon 58 may, in some embodiments, be separated into individual glass sheets 62 by a glass separation apparatus 100 in an elastic region of the glass ribbon. A robot 64 may then transfer the individual glass sheets 62 to a conveyor system using gripping tool 65, whereupon the individual glass sheets may be further processed.

[0044] FIG 2 shows a schematic side view of a stage of an example glass sheet separation process. As shown in FIG. 2, glass separation apparatus 100 includes scoring mechanism 102 and nosing 104, wherein scoring mechanism 102 and nosing 104 are positioned on opposite sides of glass ribbon 58. In the stage shown in FIG. 2, scoring mechanism 102 moves across the glass ribbon 58 in the widthwise direction (in a direction into and out of the plane of FIG. 2 as shown) and imparts a widthwise score line across the glass ribbon 58. In addition, in the stage shown in FIG. 2, gripping tool 65 has not yet engaged glass ribbon 58, although engagement while scoring is also known in the art and commonly practiced.

[0045] While scoring mechanism 102 is shown in FIG.2 as a mechanical scoring mechanism, such as a mechanism comprising a score wheel, it is to be understood that embodiments herein include other types of scoring mechanism, such as, for example, laser scoring mechanisms. When scoring mechanism 102 comprises a score wheel, the score wheel may be mounted on a ball bearing pivot which is secured to a shaft which is in turn mounted on a linear actuator (air cylinder) that moves the score wheel towards the glass ribbon 58 so it can be drawn across and score a side of the ribbon.

[0046] Nosing 104 may comprise a resilient material, such as silicon mbber. In certain exemplary embodiments, nosing 104 may be a conformable nosing that has a bowed shape of the glass ribbon 58 as disclosed, for example, in U.S. patent no. 8,051,681, the entire disclosure of which is incorporated by reference. Nosing 104 may also be in fluid communication with a vacuum source (not shown) to enhance engagement between the glass ribbon 58 and the nosing, as disclosed, for example, in U.S. patent no. 8,245,539, the entire disclosure of which is incorporated herein by reference.

[0047] FIG. 3 shows a schematic side view of another stage of an example glass sheet separation process wherein scoring mechanism 102 has disengaged glass ribbon 58 and gripping tool 65, including gripping elements 66, is actuated by robot 64 to engage glass ribbon 58. Gripping elements 66 may, for example, comprise a resilient material, such as silicone rubber, and may, in certain exemplary embodiments, comprise a cup-shaped resilient material that may be in fluid communication with a vacuum source (not shown) to enhance engagement between the glass ribbon 58 and the gripping elements 66 (gripping elements comprising cup-shaped material in fluid communication with a vacuum source are hereinafter referred to as vacuum cups).

[0048] As shown in FIG. 3, while the gripping tool 64, including gripping elements 66, imparts a pulling force on glass ribbon 58, the pulling force is not sufficient to substantially bend the glass ribbon 58 away from the draw or flow direction 60. FIG. 4, however, shows a schematic side view of yet another stage of an example glass sheet separation process wherein gripping tool 65 has been further actuated by robot 64, thereby imparting a pulling force that is sufficient to begin to bend the portion of glass ribbon 58 extending below nosing 104 away from the draw or flow direction 60. However, as shown in FIG. 4, the pulling force is not yet sufficient to substantially separate the portion of the glass ribbon 58 extending below nosing 104 from the rest of the glass ribbon 58.

[0049] FIG. 5 shows a schematic side view of still yet another stage of an example glass sheet separation process wherein gripping tool 65 has been further actuated by robot 65, thereby imparting a pulling force that is sufficient to separate the portion of the glass ribbon 58 extending below nosing 104 (i.e., glass sheet) from the rest of the glass ribbon 58. The glass sheet may then be transferred to, for example, a conveyor system for further processing.

[0050] FIG. 6 shows a perspective view of a glass sheet 62 having a first major surface 162, a second major surface 164 extending in a generally parallel direction to the first major surface 162 (on the opposite side of the glass sheet 62 as the first major surface) and an edge surface 166 extending between the first major surface 162 and the second major surface 164 and extending in a generally perpendicular direction to the first and second major surfaces 162, 164.

[0051] FIG. 7 shows a perspective view of at least a portion of a beveling process of an edge surface 166 of a glass sheet 62. As shown in FIG. 7, beveling process includes applying a grinding wheel 200 to edge surface 166, wherein the grinding wheel 200 moves relative to edge surface 166 in the direction indicated by arrow 300. Beveling process may further include applying at least one polishing wheel (not shown) to edge surface 166. Such beveling process can lead to the presence of numerous glass particles, as well as surface and sub surface damage (i.e., irregular topography), on edge surface 166.

[0052] Downstream processing of glass sheet 62 may involve application of mechanical or chemical treatments on edge surfaces 166, which can result in additional particle generation due to the presence of irregular edge surface topography. Such particles may migrate to at least one surface of glass sheets 62. Accordingly, embodiments disclosed herein include those in which irregular edge surface topography is removed, while at the same time removing and/or reducing particles present on the edge surfaces 166 (i.e.,“edge particles”) as well as removing reaction by-products that may be formed upon removal of the irregular edge surface topography.

[0053] FIG. 8 shows a perspective view of at least a portion of a treatment process of an edge surface 166 of a glass sheet 62 with a plasma jet 402. As shown in FIG. 8, treatment process includes directing a flow of plasma, via plasma jet 402, toward edge surface 166, wherein plasma jet head 400 moves relative to edge surface 166 in the direction indicated by arrow 500. In certain exemplary embodiments, plasma jet 402 comprises an atmospheric pressure plasma jet.

[0054] Embodiments disclosed herein include those in which the plasma comprises at least one high thermal conductivity component. For example, embodiments disclosed herein include those in which the plasma comprises at least one component selected from hydrogen and helium.

[0055] Plasma jet 402 can be directed toward edge surface 166 under a variety of processing parameters. In certain exemplary embodiments, plasma jet 402 can be generated at a power of at least about 300 watts, such as a power of at least about 500 watts, including a power of from about 300 watts to about 800 watts and further including a power of from about 500 watts to about 800 watts.

[0056] In certain exemplary embodiments, plasma jet 402 is generated via a direct current high voltage discharge that generates a pulsed electric arc, such as a voltage discharge of at least about 5 kV, such as from about 5 kV to about 15 kV. In certain exemplary

embodiments, plasma jet 402 is generated at a frequency of at least about 10 kHz, such as from about 10 kHz to about 1,000 kHz. In certain exemplary embodiments, plasma jet can have a beam length of from about 5 millimeters to about 40 millimeters and a widest beam width of from about 0.5 millimeters to about 15 millimeters.

[0057] In certain exemplary embodiments, the distance between the portion of plasma jet head 400 that is closest to edge surface 166 (referred to herein as“gap distance”), is at least about 1 millimeter, such as at least about 2 millimeters, and further such as at least about 4 millimeters, and yet further such as at least about 5 millimeters, such as from about 1 millimeter to about 10 millimeters, including from about 5 millimeters to about 10 millimeters.

[0058] In certain exemplary embodiments, the number of times that the plasma jet head 400 moves relative to the entire length of edge surface 166 (referred to herein as“scan pass”) can be at least 1 pass, such as at least 2 passes, and further such as at least 3 passes, and yet further such as at least 4 passes, including from 1 pass to 10 passes, and further including from 2 passes to 6 passes.

[0059] In certain exemplary embodiments, the speed of relative movement between plasma jet head 400 and edge surface 166 (referred to herein as“scan speed”) can be a function of the thickness of edge surface 166 (i.e., the distance of the extension direction of the edge surface 166 between the first major surface 162 and the second major surface 164). For example, embodiments disclosed herein include those in which a scan speed of the flow of plasma along the edge surface 166 in millimeters per second is from about 1 to about 50, such as from about 2 to about 20, of the inverse of the thickness of the edge surface 166 in millimeters.

[0060] For example, if the thickness of the edge surface is about 0.5 millimeters, a scan speed of the flow of plasma along the edge surface 166 in millimeters per second can be from about 2 to about 100 millimeters per second, such as from about 4 to about 40 millimeters per second. Similarly, if the thickness of the edge surface is about 0.1 millimeter, a scan speed of the flow of plasma along the edge surface 166 in millimeters per second can be from about 10 to about 500 millimeters per second, such as from about 20 to about 200 millimeters per second.

[0061] Applicants have specifically found that when a flow of plasma comprising at least one high thermal conductivity component, such as a flow of plasma comprising an atmospheric pressure plasma jet comprising at least one high thermal conductivity component is directed toward a glass edge surface, an edge strength of the edge surface may be improved. In addition, when a flow of plasma comprising at least one high thermal conductivity component, such as a flow of plasma comprising an atmospheric pressure plasma jet comprising at least one high thermal conductivity component is directed toward a glass edge surface, an edge impact strength of the edge surface may be improved. Such edge strength and/or edge impact strength may be further improved when the scan speed is controlled as a function of the thickness of the edge surface as described herein.

[0062] For example, embodiments disclosed herein include directing a flow of plasma toward the edge surface of a glass article, such as glass sheet 62, wherein a thickness (i.e., distance of the extension direction) of the edge surface 166 between the first major surface 162 and the second major surface 164 is less than or equal to about 0.5 millimeters, such as from about 0.1 millimeters to about 0.5 millimeters, and further such as from about 0.2 millimeters to about 0.4 millimeters, and wherein the plasma comprises at least one high thermal conductivity component, such as at least one of hydrogen and helium, and an edge strength of the glass article subsequent to directing a flow of plasma toward the edge surface 166, as measured by the four point bend test, is at least about 250 MPa, such as at least about 300 MPa, and further such as at least about 350 MPa, and yet further such as at least about 400 MPa, and still yet further such as at least about 450 MPa, including from about 250 MPa to about 500 MPa, such as from about 300 MPa to about 450 MPa. Such embodiments can include those in which a scan speed of the flow of plasma along the edge surface 166 in millimeters per second is from about 1 to about 50, such as from about 2 to about 20, of the inverse of the thickness of the edge surface 166.

[0063] Embodiments disclosed herein also include directing a flow of plasma toward the edge surface of a glass article, such as glass sheet 62, wherein a thickness (i.e., distance of the extension direction) of the edge surface 166 between the first major surface 162 and the second major surface 164 is less than or equal to about 0.5 millimeters and wherein the plasma comprises at least one high thermal conductivity component, such as at least one of hydrogen and helium, and an edge impact strength of the glass article subsequent to directing a flow of plasma toward the edge surface 166 as measured by the pendulum drop test, is at least about 20 millimeters, such as at least about 25 millimeters, and further such as at least about 30 millimeters, and yet further such as at least about 35 millimeters, and still yet further such as at least about 40 millimeters, including from about 20 millimeters to about 50 millimeters, such as from about 25 millimeters to about 45 millimeters. Such embodiments can include those in which a scan speed of the flow of plasma along the edge surface 166 in millimeters per second is from about 1 to about 50, such as from about 2 to about 20, of the inverse of the thickness of the edge surface 166.

[0064] Applicants have found including at least one high thermal conductivity component in the plasma can be particularly beneficial, for example, in generating a compressive stress in the edge surface of glasses having a coefficient of thermal expansion (CTE) of at least about 3 ppm/K in the range between about 25°C and about 300°C. Embodiments disclosed herein can also be used to generate a compressive stress in the edge surface of glasses having a CTE of less than about 3 ppm/K in the range between about 25°C and about 300°C.

[0065] In addition to comprising at least one high thermal conductivity component, such as at least one of hydrogen and helium, the plasma may, for example, comprise at least one component selected from nitrogen, argon, oxygen, and neon that is excited and at least partially converted to the plasma state. In certain exemplary embodiments, the plasma comprises hydrogen and at least one of nitrogen, argon, oxygen, and neon. In certain exemplary embodiments, the plasma comprises helium and at least one of nitrogen, argon, oxygen, and neon. In certain exemplary embodiments, the plasma comprises hydrogen and at least two of nitrogen, argon, oxygen, and neon. In certain exemplary embodiments, the plasma comprises at helium and at least two of nitrogen, argon, oxygen, and neon. In certain exemplary embodiments, the plasma comprises hydrogen, nitrogen, and at least one of argon, oxygen, and neon. In certain exemplary embodiments, the plasma comprises helium, nitrogen, and at least one of argon, oxygen, and neon. In certain exemplary embodiments, the plasma comprises hydrogen and nitrogen. In certain exemplary embodiments, the plasma comprises helium and nitrogen.

[0066] In certain exemplary embodiments, the plasma comprises at least about 1 mol%, such as at least about 3 mol%, and further such as at least about 5 mol% of at least one high thermal conductivity component, such as at least one of hydrogen and helium. In certain exemplary embodiments, plasma comprises from about 1 mol% to about 10%, such as from about 2 mol% to about 8 mol%, and further such as from about 3 mol% to about 6 mol% of at least one high thermal conductivity component, such as at least one of hydrogen and helium. When the plasma comprises at least one of nitrogen, argon, oxygen, and neon, the nitrogen content can, for example, range from about 50 mol% to about 99 mol%, the argon content can, for example, range from about 0 mol% to about 25 mol%, the oxygen content can, for example, range from about 0 mol% to about 25 mol%, and the neon content can, for example, range from about 0 mol% to about 25 mol%.

[0067] In certain exemplary embodiments, the plasma comprises from about 1 mol% to about 10%, such as from about 2 mol% to about 8 mol%, and further such as from about 3 mol% to about 6 mol% of hydrogen and from about 50 mol% to about 99 mol% of nitrogen, from about 0 mol% to about 25 mol% of argon, from about 0 mol% to about 25 mol% of oxygen, and from about 0 mol% to about 10 mol% of neon.

[0068] In certain exemplary embodiments, the plasma comprises from about 1 mol% to about 10%, such as from about 2 mol% to about 8 mol%, and further such as from about 3 mol% to about 6 mol% of helium and from about 50 mol% to about 99 mol% of nitrogen, from about 0 mol% to about 25 mol% of argon, from about 0 mol% to about 25 mol% of oxygen, and from about 0 mol% to about 10 mol% of neon.

[0069] In certain exemplary embodiments, the plasma comprises from about 1 mol% to about 10%, such as from about 2 mol% to about 8 mol%, and further such as from about 3 mol% to about 6 mol% of hydrogen, from about 75 mol% to about 99 mol% of nitrogen, and from about 0 mol% to about 25 mol% of argon. [0070] In certain exemplary embodiments, the plasma comprises from about 1 mol% to about 10%, such as from about 2 mol% to about 8 mol%, and further such as from about 3 mol% to about 6 mol% of helium, from about 75 mol% to about 99 mol% of nitrogen, and from about 0 mol% to about 25 mol% of argon.

[0071] In certain exemplary embodiments, treatment process comprising directing a flow of plasma, via plasma jet 402, toward edge surface 166, can result in a substantial reduction of particle density on edge surface 166, such as a particle density reduction of at least 1 order of magnitude, and further such as a particle density reduction of at least 2 orders of magnitude, and yet further such as a particle density reduction of at least 3 orders of magnitude. For example, directing a flow of plasma toward edge surface 166, according to embodiments disclosed herein, can reduce a density of particles on edge surface 166 to less than about 10 per 0.1 square millimeter, such as less than about 8 per 0.1 square millimeter, and further such as less than about 5 per 0.1 square millimeter, and yet further such as less than about 2 per 0.1 square millimeter, including from about 0 to about 10 particles per 0.1 square millimeter, and further including from about 1 to about 8 particles per 0.1 square millimeter, and yet further from about 2 to about 5 particles per 0.1 square millimeter.

[0072] In certain exemplary embodiments, a compressive stress can be generated in edge surface 166 subsequent to directing a flow of plasma toward the edge surface. For example, stress in edge surface 166 can be determined by the de Senarmont and Friedel optical birefringence method described in Schott AG,“TIE-27: Stress in Optical Glass”, Technical Information: Advanced Optics July 2004. When a negative stress value (in MPa) is observed in a sample using this method, then the stress in the edge surface 166 is said to be compressive.

[0073] Accordingly, embodiments disclosed herein include those having a compressive stress in edge surface 166 subsequent to directing a flow of plasma toward the edge surface, wherein the measured stress value, according to the above referenced optical birefringence method is less than about -1 MPa, such as less than about -5 MPa, and further such as less than about -10 MPa, and further such as less than about -20 MPa, and yet further such as less than about -30 MPa, such as from about -1 MPa to about -100 MPa, and further such as from about -10 MPa to about -60 MPa, and yet further such as from about -20 MPa to about -40 MPa.

[0074] Without wishing to be bound by theory, methods disclosed herein, including directing a flow of plasma toward edge surface 166, wherein the plasma comprises at least one high thermal conductivity component, can enable temperature of edge surface 166 at a time of at least one second subsequent to directing a flow of plasma toward edge surface 166 to be less than a temperature of a portion of the glass article that is at least about 5 millimeters away from edge surface 166 This can, in turn, generate a compressive stress in edge surface 166. Generation of a compressive stress in edge surface 166 can contribute to higher edge strength of glass articles, such as an edge strength of at least about 250 MPa, as measured by the four point bend test. Generation of a compressive stress in edge surface 166 can also contribute to higher edge impact strength of glass articles, such as an edge impact strength of at least about 20 millimeters, as measured by the pendulum drop test.

[0075] In certain exemplary embodiments, directing a flow of plasma toward the edge surface can result in a composition of the edge surface 166 differing from that of the glass that is at least about 5 millimeters away from the edge surface. For example, embodiments disclosed herein include those in which directing a flow of plasma toward the edge surface 166 results in an edge surface 166 comprising a silica content that is at least about 10 mol% higher, such as at least about 20 mol% higher, including from about 10 mol% higher to about 40 mol% higher than a silica content of the glass that is at least about 5 millimeters away from the edge surface 166. Embodiments disclosed herein can also include those in which directing a flow of plasma toward the edge surface 166 results in an edge surface 166 comprising an alumina content that is at least about 25 mol% lower, such as at least about 50 mol% lower, including from about 25 mol% lower to about 75 mol% lower than an alumina content of the glass that is at least about 5 millimeters away from the edge surface 166. If the glass composition comprises one or more alkali metal oxides, such as sodium oxide or potassium oxide, directing a flow of plasma toward an edge surface 166 can result in an edge surface 166 comprising an alkali metal oxide content that is at least about 25 mol% lower, such as at least about 50 mol% lower, including from about 25 mol% lower to about 75 mol% lower than an alkali metal oxide content of the glass that is at least about 5 millimeters away from the edge surface 166.

[0076] Embodiments disclosed herein include those in which plasma jet 402 is applied toward edge surface 166 after or in lieu of an edge beveling process, such as the exemplary edge beveling process shown in FIG. 7. For example, in certain exemplary embodiments, plasma jet 402 may be applied toward edge surface 166 of glass sheet 62 immediately following separation of glass sheet 62 from glass ribbon 58, as shown, for example, in FIG. 5. Alternatively, subsequent processing steps, such as the exemplary edge beveling process shown in FIG. 7, may be applied to glass sheet 62, prior to application of plasma jet 402 toward edge surface 166 of glass sheet 62. [0077] In certain exemplary embodiments, edge surface 166 may be heated, for example, by an electrical resistance heater or an induction heater, to a temperature of at least about 100°C, such as at least about 200°C, and further such as at least about 300°C, and yet further such as at least about 400°C, and still yet further such as at least about 500°C, including a temperature ranging from about 100°C to about 600°C prior to directing the flow of plasma toward the edge surface 166. Exemplary embodiments also include those in which temperature of edge surface 166 is maintained in the above-referenced ranges for a period of time subsequent to directing a flow of plasma toward the edge surface 166. Such heat treatment can potentially reduce any edge tensile stress.

[0078] Examples

[0079] Embodiments herein are further illustrated with reference to the following non limiting examples:

[0080] Example 1

[0081] Two samples of high purity fused silica glass strips having dimensions of about 150 millimeters by about 200 millimeters by about 20 millimeters were subjected to treatment with an atmospheric pressure plasma jet using a gas composition of clean dry air (CD A) according to the treatment parameters set forth in Table 1. Stress was measured by the optical birefringence method referenced above.

[0082] The treated samples and an untreated reference (i.e., comparative) sample were tested for edge strength, as measured by the four point bend test with the results set forth in FIG. 9A. The treated samples and the untreated reference sample were also tested for edge impact strength, as measured by the pendulum drop test with the results set forth in FIG. 9B. As can be seen from FIGS. 9A and 9B, treatment with the atmospheric pressure plasma jet in accordance with the treatment parameters set forth in Table 1 resulted in a substantial improvement in both edge strength and edge impact strength of the samples as compared to the untreated reference sample.

[0083] Table 1

[0084] Example 2

[0085] Eight samples of Corning Eagle XG® each having a thickness of about 0.5 millimeters, a length of about 150 millimeters, and a width of about 20 millimeters were subjected to treatment with an atmospheric pressure plasma jet according to the treatment parameters set forth in Table 2. Stress was measured by the optical birefringence method referenced above.

[0086] The treated samples and an untreated reference (i.e., comparative) sample were tested for edge strength, as measured by the four point bend test with the results set forth in FIG. 10. As can be seen from FIG. 10, treatment with the atmospheric pressure plasma jet in accordance with the treatment parameters set forth in Table 2 resulted in a substantial improvement in edge strength as compared to the untreated reference sample.

[0087] Table 2

[0088] Example 3

[0089] Two samples of Coming Eagle XG® each having a thickness of about 0.3 millimeters, a length of about 150 millimeters, and a width of about 20 millimeters were subjected to treatment with an atmospheric pressure plasma jet according to the treatment parameters set forth in Table 3. Stress was measured by the optical birefringence method referenced above.

[0090] The treated samples and an untreated reference (i.e., comparative) sample were tested for edge strength, as measured by the four point bend test with the results set forth in FIG. 11 A. The treated samples and the untreated reference sample were also tested for edge impact strength, according to the Pendulum Drop Test with the results set forth in FIG. 1 IB. As can be seen from FIGS. 11 A and 1 IB, treatment with the atmospheric pressure plasma jet in accordance with the treatment parameters set forth in Table 3 resulted in a substantial improvement in both edge strength and edge impact strength of the samples as compared to the untreated reference sample.

[0091] Table 3

[0092] Example 4

[0093] Four samples of Corning Willow® glass each having a thickness of about 0.1 millimeter, a length of about 100 millimeters, and a width of about 20 millimeters were subjected to treatment with an atmospheric pressure plasma jet according to the treatment parameters set forth in Table 4. Stress was not measured for these samples.

[0094] The treated samples and an untreated reference (i.e., comparative) sample were tested for edge strength, as measured by the two point bend test with the results set forth in FIG. 12. As can be seen from FIG. 12, treatment with the atmospheric pressure plasma jet in accordance with the treatment parameters set forth in Table 4 resulted in a substantial improvement in edge strength as compared to the untreated reference sample.

[0095] Table 4

[0096] While the above embodiments have been described with reference to a fusion down draw process, it is to be understood that such embodiments are also applicable to other glass forming processes, such as float processes, slot draw processes, up-draw processes, tube drawing processes, and press-rolling processes.

[0097] It will be apparent to those skilled in the art that various modifications and variations can be made to embodiment of the present disclosure without departing from the spirit and scope of the disclosure. Thus it is intended that the present disclosure cover such modifications and variations provided they come within the scope of the appended claims and their equivalents.

Claims

What is claimed is:

1. A method for manufacturing a glass article comprising:

forming the glass article, wherein the glass article comprises a first major surface, a second major surface parallel to the first major surface, and an edge surface extending between the first major surface and the second major surface in a perpendicular direction to the first and second major surfaces, wherein a distance of the extension direction of the edge between the first and second major surfaces is less than or equal to about 0.5 millimeters; and

directing a flow of plasma toward the edge surface, wherein the plasma comprises at least one high thermal conductivity component and an edge strength of the glass article subsequent to directing a flow of plasma toward the edge surface, as measured by the four point bend test, is at least about 250 MPa.

2. The method of claim 1, wherein the flow of plasma comprises an atmospheric pressure plasma jet.

3. The method of claim 1, wherein the at least one high thermal conductivity component comprises at least one of hydrogen and helium.

4. The method of claim 1, wherein an edge impact strength of the glass article subsequent to directing the flow of plasma toward the edge surface, as measured by the pendulum drop test, is at least about 20 millimeters

5. The method of claim 1, wherein direction of the flow of plasma toward the edge surface reduces a density of particles on the edge surface to less than about 10 per 0.1 square millimeter.

6. The method of claim 1, wherein a scan speed of the flow of plasma along the edge surface in millimeters per second is from about 1 to about 50 of the inverse of a distance of the extension direction of the edge between the first and second maj or surfaces in millimeters.

7. The method of claim 1, wherein the plasma is generated at a power of at least about 300 watts.

8. The method of claim 1, wherein subsequent to directing the flow of plasma toward the edge surface, a compressive stress is generated in the edge surface.

9. The method of claim 1, wherein subsequent to directing a flow of plasma toward the edge surface, the edge surface comprises at least one of: a silica content that is at least about 10 mol% higher than a silica content of the glass that is at least about 5 millimeters away from the edge surface; and an alumina content that is at least about 25 mol% lower than an alumina content of the glass that is at least about 5 millimeters away from the edge surface.

10. A method for treating a treating a glass article, the glass article comprising:

a first major surface, a second major surface parallel to the first major surface, and an edge surface extending between the first major surface and the second major surface in a perpendicular direction to the first and second major surfaces, wherein a distance of the extension direction of the edge between the first and second major surfaces is less than or equal to about 0.5 millimeters;

wherein the method comprises directing a flow of plasma toward the edge surface, wherein the plasma comprises at least one high thermal conductivity component and an edge strength of the glass article subsequent to directing a flow of plasma toward the edge surface, as measured by the four point bend test, is at least about 250 MPa.

11. The method of claim 10, wherein the flow of plasma comprises an

atmospheric pressure plasma jet.

12. The method of claim 10, wherein the at least one high thermal conductivity component comprises at least one of hydrogen and helium.

13. The method of claim 10, wherein an edge impact strength of the glass article subsequent to directing the flow of plasma toward the edge surface, as measured by the pendulum drop test, is at least about 20 millimeters

14. The method of claim 10, wherein direction of the flow of plasma toward the edge surface reduces a density of particles on the edge surface to less than about 10 per 0.1 square millimeter.

15. The method of claim 10, wherein a scan speed of the flow of plasma along the edge surface in millimeters per second is from about 1 to about 50 of the inverse of a distance of the extension direction of the edge between the first and second maj or surfaces in millimeters.

16. The method of claim 10, wherein the plasma is generated at a power of at least about 300 watts.

17. The method of claim 10, wherein subsequent to directing the flow of plasma toward the edge surface, a compressive stress is generated in the edge surface.

18. The method of claim 10, wherein subsequent to directing a flow of plasma toward the edge surface, the edge surface comprises at least one of: a silica content that is at least about 10 mol% higher than a silica content of the glass that is at least about 5 millimeters away from the edge surface; and an alumina content that is at least about 25 mol% lower than an alumina content of the glass that is at least about 5 millimeters away from the edge surface.

19. A glass article comprising a first major surface, a second major surface

parallel to the first major surface, and an edge surface extending between the first major surface and the second major surface in a perpendicular direction to the first and second major surfaces, wherein a distance of the extension direction of the edge between the first and second major surfaces is less than or equal to about 0.5 millimeters and an edge strength of the glass article, as measured by the four point bend test, is at least about 250 MPa

20. The glass article of claim 19, wherein a density of particles on the edge

surface is less than about 10 per 0.1 square millimeter.

21. The glass article of claim 19, wherein an edge impact strength of the glass article, as measured by the pendulum drop test, is at least about 20 millimeters.

22. The glass article of claim 19, wherein the edge surface comprises at least one of: a silica content that is at least about 10 mol% higher than a silica content of the glass that is at least about 5 millimeters away from the edge surface; and an alumina content that is at least about 25 mol% lower than an alumina content of the glass that is at least about 5 millimeters away from the edge surface.

23. The glass article of claim 19, wherein a flow of plasma has been directed toward the edge surface.

24. An electronic device comprising the glass article of claim 19.