WO2025222398A1

WO2025222398A1 - A glass with anti-abrasion coating and methods of making the same

Info

Publication number: WO2025222398A1
Application number: PCT/CN2024/089514
Authority: WO
Inventors: Xinyu Cao; Wanghui CHEN; Lingke Li; Zheng Liu; Chen SHEN; Haonan Wang; Jianqiang Zhu
Original assignee: Corning Inc
Current assignee: Corning Inc
Priority date: 2024-04-24
Filing date: 2024-04-24
Publication date: 2025-10-30
Anticipated expiration: 2026-10-24

Abstract

A glass article includes: a glass substrate comprising a first major surface, a second major surface opposite the first major surface; an anti-abrasion coating on the first major surface comprising alkali metal ions and SiO2; a mole ratio between the alkali metal ions and SiO2 ranges from 0.01 to 0.3. The anti-abrasion coating has a refractive index range from 1.43 to 1. 47 at the wavelength of 589 nm. The glass article is chemically strengthened, having a surface compressive stress of greater than 500 MPa.

Description

A GLASS WITH ANTI-ABRASION COATING AND METHODS OF MAKING THE SAME

BACKGROUND FIELD

The present disclosure generally relates to scratch-resistant glass article, more specifically, to glass with anti-abrasion coating and methods of making the same.

TECHNICAL BACKGROUND

Ion exchangeable glasses are commonly used as cover glasses and in electronic device bodies due to their enhanced surface strength. However, it remains susceptible to scratches caused by exposure to materials that are harder than glass.

Various attempts have been made to improve scratch and abrasion resistance, including manipulating the composition of the glass to increase hardness, or applying hard coatings to the glass surface. Physical or chemical vapor deposition (PVD or CVD) technologies have been preferred for making functional thin films on glass substrates due to their high film quality and consistency in thickness control. However, these technologies require heavy investment in equipment and materials. Sol-gel derived coating films are an alternative for glass functionalization, as they are versatile, cost-effective, and easy to combine with liquid deposition techniques that permit accurate control of the coating thickness. However, sol-gel coating technology has faced numerous problems, such as low fracture toughness of the layer, which is an essential property for wear performance.

In view of these considerations, there is a need for glass with protective coatings that have high hardness and toughness, as well as a method of making such glass.

SUMMARY

An aspect of this disclosure pertains to a glass article includes: a glass substrate comprising a first major surface, a second major surface opposite the first major surface; an anti-abrasion coating on the first major surface comprising alkali metal ions and SiO₂; a mole ratio between the alkali metal ions and SiO₂ ranges from 0.01 to 0.3. The anti-abrasion coating has a refractive index range from 1.43 to1.47 at the wavelength of 589 nm; the glass article is chemically strengthened, having a surface compressive stress of greater than 500 MPa.

In some embodiments, the alkali metal ions are sodium ions.

In some embodiments, a pencil hardness of the anti-abrasion coating pencil hardness of 9H or greater.

In some embodiments, a nano-indentation hardness of the anti-abrasion coating is equal or greater than 4 GPa at an indentation depth of 20%thickness of the anti-abrasion coating, as measured by a Berkovich nanoindenter.

In some embodiments, the glass article with easy-to-clean (ETC) coating comprises an average contact angle with water of 100 degrees or more after being subjected to 400,000 cycles cheesecloth testing under a load of 750 g.

In some embodiments, the anti-abrasion coating has a thickness from 10 nm to about 1000 nm, preferably from 15 to 500 nm, more preferably from 20 to 100 nm.

A further aspect of this disclosure pertains to a method for producing a glass article, comprising the following steps: (a) applying an anti-abrasion coating containing alkali metal ions and SiO₂ onto a glass substrate to create a coated glass substrate; (b) curing the coated glass substrate; (c) chemically strengthening the coated glass substrate.

In some embodiments, the anti-abrasion coating is applied to the glass substrate using one of the methods selected from spin coating, dip coating, spray coating, slot coating, or bar coating.

In some embodiments, the curing process involves heating the coating and glass article to a temperature greater than 300℃ in air, N₂ atmosphere, or vacuum.

In some embodiments, the chemical strengthening step involves immersing the coated glass substrate in molten KNO₃ or NaNO₃, or a mixture thereof, to achieve Na-K or Li-Na exchange, or both.

In some embodiments, the anti-abrasion coating is derived from a sol-gel formulation, comprising: 3 wt. %to 27 wt. %ester of orthosilicic acid based on the total weight of the sol-gel formulation; 0.03 wt. %to 3 wt. %of alkali metal salt based on the total weight of the sol-gel formulation; 0.08 wt. %to 21 wt. %of acidic solution based on the total weight of the sol-gel formulation; 60 wt. %to 93 wt. %of alcohols based on the total weight of the sol-gel formulation; 0 wt. %to 10 wt. % of H₂O based on the total weight of the sol-gel formulation.

In some embodiments, the sol-gel formulation, comprising 5 wt. %to 20 wt. %ester of orthosilicic acid based on the total weight of the sol-gel formulation.

In some embodiments, the sol-gel formulation, comprising 0.06 wt. %to 1.0 wt. %of alkali metal salt based on the total weight of the sol-gel formulation.

In some embodiments, the sol-gel formulation, comprising 0.25 wt. %to 11 wt. %of acidic solution based on the total weight of the sol-gel formulation.

In some embodiments, the sol-gel formulation comprising 72 wt. %to 85 wt. %of alcohols based on the total weight of the sol-gel formulation.

In some embodiments, the sol-gel formulation, comprising 0.5 to 5 wt. %of H₂O based on the total weight of the sol-gel formulation.

In some embodiments, the ester of orthosilicic acid is selected from at least one of tetraethyl orthosilicate, tetramethyl orthosilicate, tetrabutyl orthosilicate, and tetraisopropyl orthosilicate.

In some embodiments, the alkali metal salt solution is selected from at least one of CH3COONa, NaNO₃, Na₂SO₄, NaCl, HCOONa, CH3COOLi, LiNO₃, Li₂SO₄, LiCl, HCOOLi, CH3COOK, KNO₃, K₂SO₄, KCl, and HCOOK.

In some embodiments, the acid is selected from at least one of HNO₃, HCl, H₂SO₄, CH3COOH, and formic acid.

In some embodiments, the alcohols is selected from at least one of methanol, ethanol, isopropanol, and 1-buthanol.

In some embodiments, a method for preparing the sol-gel formulation of, includes the steps of: (a) dissolving alkali metal salt solution in deionized (DI) water; (b) adding acidic solution to the metal salt solution to form an acidic aqueous solution; (c) mixing alcohols with the acidic aqueous solution and stirring at room temperature to form a clear solution; (d) mixing ester of orthosilicic acid with alcohols and stirring at room temperature to form a clear solution; (e) blending the solution in step (c) and step (d) to form a clear and homogenous sol; and (f) stirring the sol at room temperature for over 24 hours to finish aging.

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

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

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional, schematic view of a glass article comprising a glass substrate with anti-abrasion coating disposed over the glass substrate, according to some embodiments of the disclosure.

FIG. 2 illustrates a method for producing a glass article in accordance with one or more embodiments shown and described herein.

FIG. 3 illustrates a method for preparing a sol-gel formulation, according to some embodiments of the disclosure.

FIG. 4 illustrates a dependence of the thickness of SiO₂ coating on the rotation rate of spin coating (a) , SiO₂ content in the Na-SiO₂ sol (b) , and the withdraw rate of dip coating (c) .

FIG. 5 are SEM images of anti-abrasion coating, according to some embodiments of the disclosure.

FIG. 6 illustrates results of abrasion test of an anti-abrasion coating on glass substrate.

FIG. 7 is a plot of hardness measurements of glass articles with different coatings, according to some embodiments of the disclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments, 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.

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.

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. Also, the word “or” when used without a preceding “either” (or other similar language indicating that “or” is unequivocally meant to be exclusive -e.g., only one of x or y, etc. ) shall be interpreted to be inclusive (e.g., “x or y” means one or both x or y) .

The term “and/or” shall also be interpreted to be inclusive (e.g., “x and/or y” means one or both x or y) . In situations where “and/or” or “or” are used as a conjunction for a group of three or more items, the group should be interpreted to include one item alone, all the items together, or any combination or number of the items. Moreover, terms used in the specification and claims such as have, having, include, and including should be construed to be synonymous with the terms comprise and comprising.

Unless otherwise indicated, all numbers or expressions, such as those expressing dimensions, physical characteristics, and the like, used in the specification (other than the claims) are understood to be modified in all instances by the term “approximately. ” At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the claims, each numerical parameter recited in the specification or claims which is modified by the term “approximately” should be construed in light of the number of recited significant digits and by applying ordinary rounding techniques.

All disclosed ranges are to be understood to encompass and provide support for claims that recite any and all subranges or any and all individual values subsumed by each range. For example, a stated range of 1 to 10 should be considered to include and provide support for claims that recite any and all subranges or individual values that are between and/or inclusive of the minimum value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more and ending with a maximum value of 10 or less (e.g., 5.5 to 10, 2.34 to 3.56, and so forth) or any values from 1 to 10 (e.g., 3, 5.8, 9.9994, and so forth) .

The drawings shall be interpreted as illustrating one or more embodiments that are drawn to scale and/or one or more embodiments that are not drawn to scale. This means the drawings can be interpreted, for example, as showing: (a) everything drawn to scale, (b) nothing drawn to scale, or (c) one or more features drawn to scale and one or more features not drawn to scale. Accordingly, the drawings can serve to provide support to recite the sizes, proportions, and/or other dimensions of any of the illustrated features either alone or relative to each other. Furthermore, all such sizes, proportions, and/or other dimensions are to be understood as being variable from 0-100%in either direction and thus provide support for claims that recite such values or any and all ranges or subranges that can be formed by such values.

The terms recited in the claims should be given their ordinary and customary meaning as determined by reference to relevant entries in widely used general dictionaries and/or relevant technical dictionaries, commonly understood meanings by those in the art, etc., with the understanding that the broadest meaning imparted by any one or combination of these sources should be given to the claim terms (e.g., two or more relevant dictionary entries should be combined to provide the broadest meaning of the combination of entries, etc. ) subject only to the following exceptions: (a) if a term is used in a manner that is more expansive than its ordinary and customary meaning, the term should be given its ordinary and customary meaning plus the additional expansive meaning, or (b) if a term has been explicitly defined to have a different meaning by reciting the term followed by the phrase “as used in this document shall mean” or similar language (e.g., “this term means, ” “this term is defined as, ” “for the purposes of this disclosure this term shall mean, ” etc. ) . References to specific examples, use of “i.e., ” use of the word “invention, ” etc., are not meant to invoke exception (b) or otherwise restrict the scope of the recited claim terms. Other than situations where exception (b) applies, nothing contained in this document should be considered a disclaimer or disavowal of claim scope.

Referring to FIG. 1, a glass article 100 is depicted that includes a substrate 102 comprising a first major surface 106 and a second major surface 108 opposite the first major surface 106. Further, the glass article 100 includes anti-abrasion coating 104 on the first major surface 106. As also shown in FIG. 1, the anti-abrasion coating 104 has a thickness 110. In some embodiments, the glass article 100 can include one or more anti-abrasion coating 104 disposed over the first major surface 106 and the second major surface 108 of the glass substrate 102.

The composition of the glass substrate 102 is not particularly limited and may be selected based on the desired end use. In some embodiments, the glass substrate 100 may be ion-exchangeable glasses, for example, manufactured by Corning, Inc. However, it should be understood that other glasses are contemplated and possible. For example, other types of ion-exchangeable glasses or glass-ceramics may be used to form the glass substrate 102. With respect to glass-ceramics, the material chosen for the glass substrate 102 can be any of a wide range of materials having both a glassy phase and a ceramic phase. Illustrative glass-ceramics include those materials where the glass phase is formed from a silicate, borosilicate, aluminosilicate, or boroaluminosilicate, and the ceramic phase is formed from β-spodumene, β-quartz, nepheline, kalsilite, or carnegieite. “Glass-ceramics” include materials produced through controlled crystallization of glass. In embodiments, glass-ceramics have about 30%to about 90%crystallinity. Examples of suitable glass-ceramics may include Li₂O-Al₂O₃-SiO₂ system (i.e. LAS-System) glass-ceramics, MgO-Al₂O₃-SiO₂ system (i.e. MAS-System) glass-ceramics, ZnO×Al₂O₃×nSiO₂ (i.e. ZAS system) , and/or glass-ceramics that include a predominant crystal phase including β-quartz solid solution, β-spodumene, cordierite, and lithium disilicate. The glass-ceramic substrates may be strengthened using the chemical strengthening processes disclosed herein. In one or more embodiments, MAS-System glass-ceramic substrates may be strengthened in Li₂SO₄ molten salt, whereby an exchange of 2Li⁺ for Mg²⁺ can occur.

The thickness of the glass substrate 102 may also vary depending on its end use, although in various embodiments, the thickness t of the glass substrate is greater than or equal to 30 μm and less than or equal to 2000 μm. For example, the glass substrate 100 may have a thickness of from greater than or equal to 200 μm and less than or equal to 400 μm. In various embodiments, the glass substrate 100 has a thickness of more than or equal to about 300 μm. However, it should be understood that glass substrates of any suitable thickness may be utilized. In some embodiments, the thickness of the glass substrate may be measured through interferometric methods at locations within the area of the substrate. Additionally, or alternatively, mechanical means (e.g., calipers) may be used to measure the thickness of the glass substrate. Unless otherwise specified, thickness of the glass substrate is measured by interferometric methods.

In some embodiments, the substrate 102 is selected from chemically strengthened aluminosilicate glass having a compressive stress extending from the first major surface 106 and the second major surface 108 to a selected depth of greater than 10 μm, with a compressive stress of greater than 100 MPa. In further embodiments, the substrate 102 is selected from a chemically strengthened aluminosilicate glass having a compressive stress to a depth of greater than 25 μm, with a maximum compressive stress of greater than 500 MPa. Compressive stress, including surface compressive stress (CS) levels, is measured by a surface stress meter using commercially available instruments such as the FSM-6000 (i.e., an FSM) , as manufactured by Orihara Industrial Co., Ltd. (Japan) . Surface stress measurements rely upon the accurate measurement of the stress optical coefficient (SOC) , which is related to the birefringence of the glass. SOC in turn is measured according to Procedure C (Glass Disc Method) described in ASTM standard C770-16, entitled “Standard Test Method for Measurement of Glass Stress-Optical Coefficient, ” the contents of which are incorporated herein by reference in their entirety.

In some embodiments of the glass article 100 depicted in FIG. 1, the anti-abrasion coating 104 comprises alkali metal ions and SiO₂. In some embodiments, the mole ratio between the alkali metal ions and SiO₂ can range from 0.01 to 0.3, for example, 0.02, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, and all values between these values. The source materials of the anti-abrasion coating 104 may be deposited as a single film or a multilayer coating or structure. More generally, the anti-abrasion coating 104, whether in a single film or a multilayer structure, can be characterized by a selected thickness, i.e., thickness 110 (see FIG. 1) . In some embodiments, the thickness 110 of the anti-abrasion coating 104 may be in a range of from 10 nm to about 1000 nm, preferably from 15 to 500 nm, more preferably from 20 to 100 nm.

In some embodiments, the average hardness of the anti-abrasion coating 104 at an indentation depth of 20%thickness can be about 4 GPa or more, 5 GPa or more, 6 GPa or more, 7 GPa or more, 8 GPa or more, 9 GPa or more, 10 GPa or more, 12 GPa or more, 15 GPa or more, 18 GPa or more, and all average hardness values between these values. As used herein, the “average hardness value” is reported as an average of a set of measurements on the outer surface of the anti-abrasion coating 104 using a nanoindentation apparatus. More particularly, hardness of thin film coatings as reported herein was determined using widely accepted nanoindentation practices. (See Fischer-Cripps, A.C., Critical Review of Analysis and Interpretation of Nanoindentation Test Data, Surface & Coatings Technology, 200, 4153-4165 (2006) (hereinafter “Fischer-Cripps” ) ; and Hay, J., Agee, P., and Herbert, E., Continuous Stiffness measurement During Instrumented Indentation Testing, Experimental Techniques, 34 (3) 86-94 (2010) (hereinafter “Hay” ) . ) For coatings, it is typical to measure hardness as a function of indentation depth. So long as the coating is of sufficient thickness, it is then possible to isolate the properties of the coating from the resulting response profiles. It should be recognized that if the coatings are too thin (for example, less than ～500 nm) , it may not be possible to completely isolate the coating properties as they can be influenced from the proximity of the substrate which may have different mechanical properties. (See Hay. ) The methods used to report the properties herein are representative of the coatings themselves. The process is to measure hardness and modulus versus indentation depth out to depths approaching 1000 nm. The elastic modulus and hardness values reported herein for such thin films were measured using known diamond nanoindentation methods, as described above, with a Berkovich diamond indenter tip.

In some implementations, the glass article 100 is further characterized by a pencil hardness of 9H or greater. Pencil hardness testing is conducted on the glass article 100 according to the ASTM D3363 test method. The pencil is placed in an angled holder and scratched across the surface of the glass article 100 on the side of the anti-abrasion film 104 with enough force to crush the graphite of the pencil. Accordingly, the maximum pencil hardness value in the ASTM D3363 test is associated with the hardest common pencil, a 9H pencil.

According to some embodiments of the glass article 100 depicted in FIG. 1, the anti-abrasion coating 104 is transparent or substantially transparent. In some embodiments, anti-abrasion coating has a refractive index range from 1.43 to1.47 at the wavelength of 589 nm, preferably in a range from 1.44 to 1.45.

The glass article 100 may be chemically strengthened. As used herein, chemically strengthened can be achieved through ion-exchange of larger ions for smaller ions in the surface of the substrate, where the ions in the surface layer of the substrate are replaced by-or exchanged with-larger ions having the same valence or oxidation state. Ion exchange processes are typically carried out by immersing a substrate in a molten salt bath containing the larger ions to be exchanged with the smaller ions in the substrate. It will be appreciated by those skilled in the art that parameters for the ion exchange process, including, but not limited to, bath composition and temperature, immersion time, the number of immersions of the substrate in a salt bath (or baths) , use of multiple salt baths, additional steps such as annealing, washing, and the like, are generally determined by the composition of the substrate and the desired compressive stress (CS) , depth of compressive stress layer (or depth of compression, DOC) of the substrate that result from the strengthening operation. By way of example, ion exchange of alkali metal-containing glass substrates may be achieved by immersion in at least one molten bath containing a salt such as, but not limited to, nitrates, sulfates, and chlorides of the larger alkali metal ion. The temperature of the molten salt bath typically is in a range from about 380° C. up to about 450° C., and any ranges and sub-ranges between the foregoing values, while immersion times range from about 15 minutes up to about 40 hours, and any ranges and sub-ranges between the foregoing values. However, temperatures and immersion times different from those described above may also be used.

In addition, non-limiting examples of ion exchange processes in which glass substrates are immersed in multiple ion exchange baths, with washing and/or annealing steps between immersions, are described in U.S. patent application Ser. No. 12/500,650, filed Jul. 10, 2009, by Douglas C. Allan et al., entitled “Glass with Compressive Surface for Consumer Applications” and claiming priority from U.S. Provisional Patent Application No. 61/079,995, filed Jul. 11, 2008, in which glass substrates are strengthened by immersion in multiple, successive, ion exchange treatments in salt baths of different concentrations; and U.S. Pat. No. 8,312,739, by Christopher M. Lee et al., issued on Nov. 20, 2012, and entitled “Dual Stage Ion Exchange for Chemical Strengthening of Glass, ” and claiming priority from U.S. Provisional Patent Application No. 61/084,398, filed Jul. 29, 2008, in which glass substrates are strengthened by ion exchange in a first bath is diluted with an effluent ion, followed by immersion in a second bath having a smaller concentration of the effluent ion than the first bath. The contents of U.S. patent application Ser. No. 12/500,650 and U.S. Pat. No. 8,312,739 are incorporated herein by reference in their entirety.

The degree of chemical strengthening achieved by ion exchange may be quantified based on the parameters of central tension (CT) , surface CS, and depth of compression (DOC) . Surface CS may be measured near the surface or within the strengthened glass at various depths. A maximum CS value may include the measured CS at the surface (CSs) of the strengthened substrate. Maximum CT values are measured using a scattered light polariscope (SCALP) technique known in the art.

Compressive stress (at the surface of the glass) is measured by surface stress meter (FSM) using commercially available instruments such as the FSM-6000, manufactured by Orihara Industrial Co., Ltd. (Japan) . Surface stress measurements rely upon the accurate measurement of the stress optical coefficient (SOC) , which is related to the birefringence of the glass. SOC in turn is measured according to Procedure C (Glass Disc Method) described in ASTM standard C770-16, entitled “Standard Test Method for Measurement of Glass Stress-Optical Coefficient, ” the contents of which are incorporated herein by reference in their entirety.

As used herein, depth of compression (DOC) means the depth at which the stress in the chemically strengthened alkali aluminosilicate glass article described herein changes from compressive to tensile. DOC may be measured by FSM or by SCALP depending on the ion exchange treatment. Where the stress in the glass article is generated by exchanging potassium ions into the glass article, FSM is used to measure DOC. Where the stress is generated by exchanging sodium ions into the glass article, SCALP is used to measure DOC. Where the stress in the glass article is generated by exchanging both potassium and sodium ions into the glass, the DOC is measured by SCALP, since it is believed the exchange depth of sodium indicates the DOC and the exchange depth of potassium ions indicates a change in the magnitude of the compressive stress (but not the change in stress from compressive to tensile) ; the exchange depth of potassium ions in such glass articles is measured by FSM.

In some embodiments, the strengthened glass article can have a surface CS of 500 MPa or greater, 550 MPa or greater, 600 MPa or greater, 650 MPa or greater, 700 MPa or greater, 750 MPa or greater or 800 MPa or greater, and any ranges and sub-ranges between the foregoing values. The strengthened substrate may have a DOC of 10 μm or greater, 15 μm or greater, 20 μm or greater (e.g., 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm or greater) , and any ranges and sub-ranges between the foregoing values, and/or a CT of 10 MPa or greater, 20 MPa or greater, 30 MPa or greater, 40 MPa or greater (e.g., 42 MPa, 45 MPa, or 50 MPa or greater) , and any ranges and sub-ranges between the foregoing values, but less than 100 MPa (e.g., 95, 90, 85, 80, 75, 70, 65, 60, 55 MPa or less) , and any ranges and sub-ranges between the foregoing values. In one or more specific embodiments, the strengthened substrate has one or more of the following: a surface CS greater than 500 MPa, a DOC greater than 15 μm, and a CT greater than 18 MPa.

The glass article 100 further includes an easy-to-clean (ETC) coating (not shown in FIG. 1) disposed over the anti-abrasion coating 104. As understood by those with ordinary skill in the field of the disclosure, various source materials can be used to form the ETC coating of the glass articles 100. ETC coating source materials may comprise perfluoropolyether (PFPE) silanes, perfluoropolyether (PFPEs) alkoxy silanes, copolymers of these PFPEs and mixtures of these PFPEs. The glass article 100 with ETC coating comprises an average contact angle with water of 100 degrees or more after being subjected to 400,000 cycles cheesecloth testing under a load of 750 g. As used herein, the “cheesecloth abrasion test” is a test employed to determine the durability of an easy-to-clean (ETC) coating deposited on a substrate of interest. The abrasion resistance is tested using a Linear Taber Abrader (Model 5750; Taber Industries, North Tonawanda, NY) with a cylindrical tip with a radius of 2 cm, affixed with 4 layers of cheesecloth wrap (Crockmeter Squares for American Standards, 200877; SDL Atlas USA, Rock Hill, SC) and with a constant load of 750 g. The pathlength of each swipe is 15 mm, with each cycle comprising a forward and backward swipe and returning the tip to its original position before proceeding with the next cycle. The speed was 30 cycles per minute, testing under ambient temperature (23℃) .

EXAMPLES

Various embodiments of the present disclosure can be better understood by reference to the following Examples which are offered by way of illustration. The present disclosure is not limited to the Examples given herein.

Example 1: Method for producing a glass article

FIG. 2 illustrates a method for producing a glass article in accordance with one or more embodiments disclosed herein. The method includes the following steps: (a) applying an anti-abrasion coating 104 containing alkali metal ions and SiO₂ onto chemically strengthened glass substrates 102, such as Gorilla 3 from Corning Inc. (abbreviated as GG3 glass or GG3) to create a coated glass substrate, using one of the following methods: spin coating, dip coating, spray coating, slot coating, or bar coating. The coating process can be repeated after step (b) for desired thickness. (b) The coated glass substrate is then cured by heating the coating and glass article to a temperature greater than 300℃ in air, N₂ atmosphere, or vacuum. (c) chemically strengthening the coated glass substrate for high mechanical properties to obtain the glass article 100. the chemical strengthening step involves immersing the coated glass substrate in molten KNO₃ or NaNO₃, or a mixture thereof, to achieve Na-K or Li-Na exchange, or both. In some embodiments, the chemically strengthening process is carried out the process in a 100%KNO₃ salt bath at 440℃ for 4 hours after the curing step; Then the coated glass substrate was slowly cooled to room temperature for an hour after the IOX process. Before step (a) , the glass substrate 102 may undergo cleaning and plasma irradiation to enhance wettability for coating.

Example 2: Method for producing a sol-gel formulation

The anti-abrasion coating 104 is derived from a sol-gel formulation, which includes an ester of orthosilicic acid ranging from 3 wt. %to 27 wt. %based on the total weight of the sol-gel mixture, an alkali metal salt in a concentration of 0.03 wt. %to 3 wt. %, an acidic solution varying from 0.08 wt. %to 21 wt. %, and alcohols ranging from 60 wt. %to 93 wt. %. The formulation can also include up to 10 wt. %of H₂O. Preferred formulations are identified within these ranges, such as the sol-gel mixture containing an ester of orthosilicic acid in the range of 5 wt. %to 20 wt. %. Additionally, preferred concentrations for the other components are as follows: alkali metal salt at 0.06 wt. %to 1.0 wt. %, acidic solution at 0.25 wt. %to 11 wt. %, alcohols at 72 wt. %to 85 wt. %, and H2O at 0.5 to 5 wt. %, all relative to the total weight of the sol-gel mixture. The ester of orthosilicic acid is selected from at least one of tetraethyl orthosilicate, tetramethyl orthosilicate, tetrabutyl orthosilicate, and tetraisopropyl orthosilicate. The alkali metal salt solution is selected from at least one of NaAc, NaNO₃, Na₂SO₄, NaCl, HCOONa, LiAc, LiNO₃, Li₂SO₄, LiCl, HCOOLi, KAc, NO₃, K₂SO₄, KCl, and HCOOK. The acid is selected from at least one of HNO₃, HCl, H₂SO₄, HAc, and formic acid. The alcohols is selected from at least one of methanol, ethanol, isopropanol, and 1-buthanol.

In some embodiments, the sol-gel formulation includes tetraethyl orthosilicate (TEOS) , anhydrous sodium acetate (NaAc) , nitric acid (HNO₃) , distilled water (H₂O) and ethanol (EtOH) . AR grade TEOS (98%) was purchased from Meryer (Shanghai) Chemical Technology Co., Ltd. AR grade NaAc (99%) was bought from Shanghai Aladdin Bio-chemical Technology Co., LTD. Nitric acid (67.2%) and EtOH (water ＜ 0.3%) was obtained from China National Pharmaceutical Group Corporation. Substrates employed in the experiments include glass coupons (50x50x1.1mm) and silicon wafers (50x50x0.7mm) . All glass coupons were ground by a CNC machine after cut to suitable sized pieces. Silicon wafers were single side polished.

FIG. 3 illustrates a method for preparing the Na-SiO₂ sol-gel used in the anti-abrasion coating 104 according to some embodiment. To prepare the hybrid Na solution, NaAc is first dissolved in distilled water with 200 RPM stirring. HNO₃ is then added, followed by some EtOH in sequence, and the stirring is continued until a clear solution is formed. To prepare the SiO₂ solution, TEOS is diluted with EtOH and stirred at 200 RPM for 10 minutes to form a clear solution. The hybrid Na solution is then mixed with the SiO₂ solution and stirred at 200 RPM for 2 hours to form a clear Na-SiO₂ sol. Before coating, the sol should be sealed and aged in ambient conditions for at least 20 hours. The sol recipe used in the experiments is listed in Table 1.

Table 1 describes recipe of Na-SiO₂ sol-gel in molar ratio.

The thickness of the anti-abrasion coating can be easily adjusted by varying the withdrawal rate (for dip coating) or rotation rate (for spin coating) , or by diluting the sol with EtOH. In some embodiments, the sol used in the coating process contains 1mol TEOS, 0.05mol NaAc, 0.11mol HNO₃, 20mol EtOH, and 7mol H₂O, with an equivalent SiO₂ content of about 4.82%. The relationship between the thickness of the coating and the rotation rate can be well-fitted by a 2-order polynomial, with the thickness decreasing from 92 nm to 64 nm as the rotation rate increases from 4000 RPM to 10000 RPM (FIG. 4A) . Diluting the coating sol is another effective method to obtain a thinner film, with the thickness ranging from 25 nm to 80 nm for equivalent SiO₂ content in the sol (FIG. 4B) . It is predictable that the thickness of the coating can reach 10 nm when the equivalent SiO₂ content is reduced to 0.7%in the sol. FIG. 4C represents the thickness of the coating made with the basic sol. The relationship between the thickness and withdrawal rate is also well-fitted by a 2-order polynomial, with the thickness increasing from 80 nm to 210 nm as the withdrawal rate increases from 1 mm/sto 6 mm/s.

Example 3: Characterization

The morphology and thickness analysis of the sol-gel coating were investigated by the SEM (Hitachi S4800) .

Compressive stress (CS) , depth of layer (DOL) , and center tension (CT) were measured by a surface stress meter (FSM-6000LE) .

Ring-on-Ring (RoR) strength was tested on Instron 5967. The glass coupon was laminated with a tape (3M 471) on one side, and a Teflon film on the other side (the tension side during the test) before the test.

The abrasion test was conducted by an abrasion tester (TABER INDUSRIES, 5900 RECIPROCATING ABRASER) . The 20 mm diameter of tester head was wrapped up with 5 layers of medical gauze (Oujie) . The speed was set at 60 single trips per min. The length of a single trip was 15mm. The load on the tester head was 750 g. Before the test, a layer of ETC coating was added on the surface by soaking in MFX 102 (Daikin) solution for 5 mins, subsequently heated at 120℃ for 30mins. Thus, the water contact angle (WCA) reached 115°. During the abrasion, the WCA was measured every 100k trips of abrasion, the medical gauze was replaced simultaneously. The WCA was measured at 5 positions in the abrasion area. The WCA was measured by a contact angle system (Dataphysics Instruments, OCA25) .

Pencil hardness was determined by a portable pencil scratch tester (Grow Instrument, QHQ-A) . Different hardness of pencils (MITSU-BISHI) were employed in the test.

The indent hardness was measured by a Nano Indenter (Keysight G200) .

The thickness of the coating on silicon wafer was determined by an ellipsometry solutions (J.A. Woollam Co. ) .

Table 2 shows the properties of samples after chemical strengthening.

Table 2 indicates that the Na-SiO₂ coatings (also referred to as Na doping coatings) have negligible effects on the chemical strengthening specifications of GG3 glass. The properties of GG3 glass with Na-SiO₂ coatings are similar to those of bare GG3 glass, indicating that the coating does not compromise the chemical strengthening performance of the glass. Furthermore, the Na-SiO₂ coating remains uniform on the substrate after undergoing the IOX process. This ensures consistent performance across the entire surface of the coated glass substrate. The IOX process does not affect the chemical composition or mechanical properties of the coating, making it an ideal choice for applications that require high durability and reliability.

The Na-SiO₂ coating prepared using the method described herein exhibits excellent morphology and adhesion properties. As shown in FIG. 5, the coating appears flat and displays fine texture when viewed from the top. The cross-sectional view of the coating reveals a dense structure that is well-bonded to the glass substrate, with no visible interface between the coating and the glass. After undergoing the IOX process, the top views of the coating remain similar to those before the process, indicating that the density of the Na-SiO₂ coating does not change significantly. However, the thickness of the coating increases by about 12%after the IOX process, as shown in FIG. 5b2. This expansion in thickness is likely due to the incorporation of larger ions into the coating during the IOX process. Overall, the Na-SiO₂ coating prepared using the method described herein exhibits excellent morphology and adhesion properties, even after undergoing the IOX process.

FIG. 6 shows the results of an abrasion test conducted on GG3 glass coated with the SiO₂ anti-abrasion coating 104 after undergoing the IOX process. The test was performed using cheese cloth at a load of 750 g, and the water contact angle (WCA) was measured every 100k single trips of abrasion. The data for the sample made with Na doping (Receipt #3 in Table 1) is shown in FIG. 6a (left) , while the data for the sample prepared without Na doping (Receipt #1 in Table 1) is exhibited in FIG. 6b (right) . Prior to the abrasion test, a layer of ETC (easy to clean) coating was applied to both samples, and the initial water contact angle exceeded 115°. The results demonstrate that the addition of NaAc to the SiO₂ coating significantly improves its anti-abrasion properties. The WCA of the coating prepared with NaAc remained above 100° even after 400,000 trips of abrasion, indicating that the coating is highly resistant to wear and tear. In contrast, the WCA of the sample made without NaAc fell below 100° after only 100k trips of abrasion, indicating that the coating is less durable compared to the Na-doped SiO₂ coating.

The mechanical performance of the Na-SiO₂ coating was evaluated using pencil hardness testing. The results are presented in Table 3, which shows that the pencil hardness of the SiO₂ coating made without NaAc is 6H, while all the coatings prepared with NaAc addition reach 9H. This indicates that the addition of NaAc significantly improves the mechanical performance of the coating. To obtain a thicker film, all the coatings were fabricated by two rounds of dipping. The thickness of the coating was measured using SEM.

Table 3 shows the pencil and indenter hardness of different samples

Nanoindentation tests were conducted to evaluate the mechanical performance of SiO₂ coatings with and without Na doping. The results, presented in FIG. 7, demonstrate that the addition of NaAc and HNO₃ significantly improves the indenter hardness of the coating. Specifically, the indenter hardness of coating3 with Na doping reaches about 2.1 GPa at 40 nm displacement into the surface, compared to 1.6 GPa for coating1 without Na doping. Furthermore, reducing the HNO₃/TEOS molar ratio to 0.11 further increases the hardness of the coating, with coating5 exhibiting a hardness of about 3.5 GPa. The post-IOX Na-SiO₂ coating exhibits even higher hardness, with coating4 and coating6 exhibiting hardness values of about 2.3 and 4.3 GPa, respectively, as shown in FIG. 7b. However, the hardness of post-IOX coating2 reduces to about 0.2 GPa. Overall, the Na-SiO₂ coating prepared with a NaAc/TEOS molar ratio of 0.05 and an HNO₃/TEOS molar ratio of 0.11 exhibits the highest indenter hardness. Additionally, the hardness of the coating is further improved after undergoing the IOX process.

The Na-SiO₂ coating prepared with a NaAc/TEOS molar ratio of 0.05 and an HNO₃/TEOS molar ratio of 0.11 exhibits superior mechanical performance compared to SiO₂ coatings without Na doping. The Na doping significantly improves the pencil hardness of the coating, making it more resistant to scratches and other forms of wear and tear. Additionally, the Na-SiO₂ coating exhibits higher indenter hardness, making it more durable and reliable. Furthermore, the hardness of the Na-SiO₂ coating is further improved after undergoing the IOX process. The porosity of SiO₂ coatings without Na doping increases after the IOX process, while this change cannot be observed in the strengthened Na-SiO₂ coating. Correspondingly, the indenter hardness of the strengthened Na-SiO₂ coating is much higher than that of SiO₂ coatings without any Na doping. The Na doping SiO₂ coating has several advantages over traditional SiO₂ coatings. It exhibits higher mechanical performance, making it more resistant to scratches and other forms of wear and tear. Additionally, it maintains its mechanical properties even after prolonged exposure to the IOX process, making it ideal for use in electronic devices, automotive windshields, and architectural glass. Overall, the Na doping SiO₂ coating provides superior mechanical performance, making it a highly desirable material for a wide range of applications.

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

Claims

A glass article comprising:

a glass substrate comprising a first major surface, a second major surface opposite the first major surface;

an anti-abrasion coating on the first major surface comprising alkali metal ions and SiO₂;

wherein a mole ratio between the alkali metal ions and SiO₂ ranges from 0.01 to 0.3.

wherein the anti-abrasion coating has a refractive index range from 1.43 to1.47 at the wavelength of 589 nm;

wherein the glass article is chemically strengthened, having a surface compressive stress of greater than 500 MPa.
The glass article of claim 1, wherein the alkali metal ions are sodium ions.
The glass article of claim 1, wherein a pencil hardness of the anti-abrasion coating pencil hardness of 9H or greater.
The glass article of claim 1, wherein a nano-indentation hardness of the anti-abrasion coating is equal or greater than 4 GPa at an indentation depth of 20%thickness of the anti-abrasion coating, as measured by a Berkovich nanoindenter.
The glass article of claim 1, wherein the glass article with easy-to-clean (ETC) coating comprises an average contact angle with water of 100 degrees or more after being subjected to 400,000 cycles cheesecloth testing under a load of 750g.
The glass article of claim 1, wherein the anti-abrasion coating has a thickness from 10 nm to about 1000 nm, preferably from 15 to 500 nm, more preferably from 20 to 100 nm.
A method for producing a glass article, comprising the following steps:

(a) applying an anti-abrasion coating containing alkali metal ions and SiO₂ onto a glass substrate to create a coated glass substrate;

(b) curing the coated glass substrate;

(c) chemically strengthening the coated glass substrate.
The method of claim 7, wherein the anti-abrasion coating is applied to the glass substrate using one of the methods selected from spin coating, dip coating, spray coating, slot coating, or bar coating.
The method of claim 7, wherein the curing process involves heating the coating and glass article to a temperature greater than 300℃ in air, N₂ atmosphere, or vacuum.
The method of claim 7, wherein the chemical strengthening step involves immersing the coated glass substrate in molten KNO₃ or NaNO₃, or a mixture thereof, to achieve Na-K or Li-Na exchange, or both.
The method of claim 7, wherein the anti-abrasion coating is derived from a sol-gel formulation, comprising:

3 wt. %to 27 wt. %ester of orthosilicic acid based on the total weight of the sol-gel formulation;

0.03 wt. %to 3 wt. %of alkali metal salt based on the total weight of the sol-gel formulation;

0.08 wt. %to 21 wt. %of acidic solution based on the total weight of the sol-gel formulation;

60 wt. %to 93 wt. %of alcohols based on the total weight of the sol-gel formulation;

0 wt. %to 10 wt. % of H₂O based on the total weight of the sol-gel formulation.
The method of claim 11, wherein the sol-gel formulation, comprising 5 wt. %to 20 wt. %ester of orthosilicic acid based on the total weight of the sol-gel formulation.
The method of claim 11, wherein the sol-gel formulation, comprising 0.06 wt. %to 1.0 wt. %of alkali metal salt based on the total weight of the sol-gel formulation.
The method of claim 11, wherein the sol-gel formulation, comprising 0.25 wt. %to 11 wt. %of acidic solution based on the total weight of the sol-gel formulation.
The method of claim 11, wherein the sol-gel formulation comprising 72 wt. %to 85 wt. %of alcohols based on the total weight of the sol-gel formulation.
The method of claim 11, wherein the sol-gel formulation, comprising 0.5 to 5 wt. %of H₂O based on the total weight of the sol-gel formulation.
The method of claim 11, wherein the ester of orthosilicic acid is selected from at least one of tetraethyl orthosilicate, tetramethyl orthosilicate, tetrabutyl orthosilicate, and tetraisopropyl orthosilicate.
The method of claim 11, wherein the alkali metal salt solution is selected from at least one of CH₃COONa, NaNO₃, Na₂SO₄, NaCl, HCOONa, CH₃COOLi, LiNO₃, Li₂SO₄, LiCl, HCOOLi, CH₃COOK, KNO₃, K₂SO₄, KCl, and HCOOK.
The method of claim 11, wherein the acid is selected from at least one of HNO₃, HCl, H₂SO₄, CH3COOH, and formic acid.
The method of claim 11, wherein the alcohols is selected from at least one of methanol, ethanol, isopropanol, and 1-buthanol.
A method for preparing the sol-gel formulation of claim 11, comprising the steps of:

(a) dissolving alkali metal salt solution in deionized (DI) water;

(b) adding acidic solution to the metal salt solution to form an acidic aqueous solution;

(c) mixing alcohols with the acidic aqueous solution and stirring at room temperature to form a clear solution;

(d) mixing ester of orthosilicic acid with alcohols and stirring at room temperature to form a clear solution;

(e) blending the solution in step (c) and step (d) to form a clear and homogenous sol; and

(f) stirring the sol at room temperature for over 24 hours to finish aging.