BACKGROUND

[0001] This application claims the benefit of priority of U.S. Provisional Application Serial No. 62/632,226 filed on February 19, 2018 the contents of which are relied upon and incorporated herein by reference in their entirety as if fully set forth below.

BACKGROUND

[0002] This disclosure relates to glass articles, and more particularly to laminated glass articles comprising a plurality of glass layers and methods for forming the same. Glass articles can be used in a wide variety of products including, for example, auto-glazing, architectural panels, appliances, and cover glass (e.g., for sensors, cameras, etc.). Depending on the particular use, the glass articles require specific mechanical, optical, and aesthetic qualities. For example, the glass article may need to withstand certain environmental conditions based on a particular application. Further, the glass article may need to transmit light at certain wavelengths while blocking the transmission of light at other wavelengths.

Still further, the glass article may be a prominent feature of an overall design such that the glass article must be able to aesthetically blend with the overall design.

SUMMARY

[0003] In one aspect, embodiments of a laminated glass article are provided. The article has a core layer, a first cladding layer, and a second cladding layer. The core layer includes a core glass composition having a core coefficient of thermal expansion (CTE). The first cladding layer has a first interface with the core layer and has a first surface opposing the first interface. The second cladding layer has a second interface with the core layer and has a second surface opposing the second interface. The core layer is disposed between the first cladding layer and the second cladding layer such that the first surface and the second surface form opposing outer surfaces of the laminated glass article. Each of the first cladding layer and the second cladding layer are made of a clad glass composition having a clad CTE. The clad CTE is less than the core CTE such that each of the first cladding layer and the second cladding layer is under a compressive stress and the core layer is under a tensile stress. The laminated glass article is substantially infrared transparent such that at least 70% of light having a wavelength of from 1000 nm to 2400 nm that is incident on the first surface is transmitted through the second surface. The laminated glass article substantially absorbs visible light such that no more than 10% of light having a wavelength of from 380 nm to 750 nm that is incident on the first surface is transmitted through the second surface.

[0004] In another aspect, embodiments of the disclosure relate to a method of forming a laminated glass article. In the method, a core glass composition that is substantially infrared transparent such that at least 80% of light having a wavelength of from 1000 nm to 2400 nm is transmitted through the core glass composition is selected. Further, the core glass composition also substantially absorbs visible light such that no more than 10% of light having a wavelength of from 380 nm to 750 nm is transmitted through the core glass composition. The core glass composition is fed in a viscous state into a first trough, and the core glass composition has a core coefficient of thermal expansion (CTE). A clad glass composition is fed in a viscous state into a second trough. The second trough is arranged above the first trough, and the clad glass composition having a clad CTE that is less than the core CTE. The first trough is overflowed with the core glass composition such that the core glass composition flows down opposing forming surfaces and converges at a draw line to form a core layer. The second trough is overflowed with the clad glass composition such that the clad glass composition flows over the core glass composition to form a first cladding layer and a second cladding layer in which the core layer is disposed between and fused to the first cladding layer and the second cladding layer. A ribbon of the core layer, the first cladding layer, and the second cladding layer is drawn and severed to form the laminated glass article.

[0005] In still another aspect, embodiments of a LiDAR cover for a LiDAR sensor are provided. The LiDAR cover is configured to transmit infrared light having a wavelength from 1000 nm to 2400 nm. In the LiDAR cover, a core layer is disposed between a first glass cladding layer and a second glass cladding layer. The core layer is made of a core glass composition having a core coefficient of thermal expansion (CTE). Each of the first glass cladding layer and the second glass cladding layer are made of a clad glass composition having a clad CTE. The clad CTE is less than the core CTE such that each of the first glass cladding layer and the second glass cladding layer is under a compressive stress and the core layer is under a tensile stress. The core layer substantially absorbs visible light such that no more than 10% of light having a wavelength of from 380 nm to 750 nm that is incident on a first outer surface is transmitted through a second outer surface.

[0006] Additional features and advantages will be set forth in the detailed description that follows, and, in part, will be readily apparent to those skilled in the art from the description or recognized by practicing the embodiments as described in the written description and claims hereof, as well as the appended drawings.

[0007] It is to be understood that both the foregoing general description and the following detailed description are merely exemplary, and are intended to provide an overview or framework to understand the nature and character of the claims.

[0008] The accompanying drawings are included to provide a further understanding and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiment s), and together with the description serve to explain principles and the operation of the various embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. l is a LiDAR sensor including a LiDAR cover, according to an exemplary embodiment.

[0010] FIG. 2 is a vehicle including the LiDAR sensor of FIG. 1, according to an exemplary embodiment.

[0011] FIG. 3 is a cross-sectional schematic view of a glass article usable as a LiDAR cover, according to an exemplary embodiment.

[0012] FIG. 4 is a cross-sectional schematic view of an overflow distributor that can be used to form a glass article, according to an exemplary embodiment.

[0013] FIG. 5 is a graph of visible and infrared light transmittance for a core material of a glass article, according to an exemplary embodiment.

[0014] FIG. 6 is a graph of visible and infrared light transmittance for three core materials usable in a glass article, according to an exemplary embodiment. [0015] FIG. 7 is a boxplot of the fail stress for a glass article as described herein as compared to a chemically strengthened glass article, according to an exemplary embodiment.

[0016] FIG. 8 is a graph comparing the level of surface defect formation for a glass article as described herein as compared to a chemically strengthened article, according to an exemplary embodiment.

DETAILED DESCRIPTION

[0017] Referring generally to the figures, embodiments of laminated glass articles suitable for use in light detection and ranging (LiDAR) applications are provided. More particular, the laminated glass articles are suitable for LiDAR applications on vehicles. The suitability of the laminated glass articles for LiDAR relates to the layered construction of the laminated glass articles in which cladding layers provide mechanical robustness while at least an internal core layer absorbs visible light and transmits infrared light. Accordingly, the laminated glass articles are able to resist scratching and cracking when exposed to

environmental abrasives. Further, in embodiments, the core layer absorbs visible light to provide the laminated glass article with an aesthetically-pleasing deadfront while also transmitting infrared light for the sending and receiving of LiDAR signals. Embodiments of the laminated glass articles disclosed herein are produced through an overflow distribution technique including two troughs, one for the cladding layers and one for the core layer.

Using this technique, the laminated glass articles have compressive layers as thick as the cladding layers, leading to enhanced toughening and improved mechanical reliability. These and other embodiments are presented herein by way of example and not by way of limitation.

[0018] Referring now to FIG. 1, an exemplary embodiment of a LiDAR sensor 10 is provided. The LiDAR sensor 10 generally includes a housing 12 and a base 14. The housing 12 rotates on the base 14 via shaft 16. Within the housing 12, the LiDAR sensor 10 may have several lasers (not shown) that are arranged to direct light onto objects around the LiDAR sensor 10. Additionally, the LiDAR sensor 10 may include multiple detectors (not shown) for receiving reflections of the laser light off of objects. The housing 12 may rotate 360° on the shaft 16 in order to develop a rendering of the surroundings around the LiDAR sensor 10. In order to protect the lasers and detectors, a LiDAR cover 18 is installed on the housing 12. While protecting the lasers and detectors, the LiDAR cover 18 must also be able to transmit the laser light that is sent from the laser and reflected from the surrounding objects. The LiDAR cover 18 disclosed herein is specifically designed for use with infrared lasers, such as lasers providing light at a wavelength between 1000 nm and 2000 nm. In a particular embodiment, the LiDAR cover 18 is designed to transmit light at 1550 nm.

[0019] As shown in FIG. 2, the LiDAR sensor 10 is mounted to a vehicle 20. While the vehicle depicted is an automobile, the LiDAR sensor 10 could also be mounted to another vehicle, such as a train, boat, plane, motorcycle, semi-trailer truck, etc. Further, while the LiDAR sensor 10 is mounted to the vehicle 20 in the sense of an aftermarket-style addition, the LiDAR sensor 10 could also be integrated into the design of the vehicle 20, such as by providing a series of LiDAR sensors 10 around the body of the vehicle. In each of these cases, the LiDAR sensors 10 are provided with a LiDAR cover 18 that is made from a laminated glass article 100 shown schematically in FIG. 3.

[0020] FIG. 3 is a cross-sectional view of one exemplary embodiment of a laminated glass article 100. In some embodiments, glass article 100 comprises a laminated sheet comprising a plurality of glass layers. The laminated sheet can be substantially planar as shown in FIG. 3 or non-planar. Glass article 100 comprises a core layer 102 disposed between a first cladding layer 104 and a second cladding layer 106. In some embodiments, first cladding layer 104 and second cladding layer 106 are exterior layers as shown in FIG. 3. For example, an outer surface 108 of first cladding layer 104 serves as an outermost surface on one side of glass article 100 and/or an outer surface 110 of second cladding layer 106 serves as an outermost surface of the glass article 100 on the other side of glass article 100. In the embodiment shown in FIG. 3, surfaces 108 and 110 are opposing, planar, and parallel exterior surfaces of glass article 100. In other embodiments, the first cladding layer 104 and/or the second cladding layer 106 are intermediate layers disposed between the core layer 102 and one or more additional exterior layers.

[0021] Core layer 102 comprises a first major surface and a second major surface opposite the first major surface. In some embodiments, first cladding layer 104 is fused to the first major surface of core layer 102. Additionally, or alternatively, second cladding layer 106 is fused to the second major surface of core layer 102. In such embodiments, an interface 112 between first cladding layer 104 and core layer 102 and/or an interface 114 between second cladding layer 106 and core layer 102 are free of any bonding material such as, for example, an adhesive, a coating layer, or any non-glass material added or configured to adhere the respective cladding layers to the core layer. Thus, first cladding layer 104 and/or second cladding layer 106 are fused directly to core layer 102 or are directly adjacent to core layer 102. In some embodiments, the glass article 100 comprises one or more intermediate layers disposed between the core layer 102 and the first cladding layer 104 and/or between the core layer 102 and the second cladding layer 106. For example, the intermediate layers comprise intermediate glass layers and/or diffusion layers formed at the interface of the core layer 102 and the cladding layer. The diffusion layer can comprise a blended region comprising components of each layer adjacent to the diffusion layer (e.g., a blended region between two directly adjacent glass layers). In some embodiments, glass article 100 comprises a glass-glass laminate (e.g., an in situ fused multilayer glass-glass laminate) in which the interfaces between directly adjacent glass layers are glass-glass interfaces.

[0022] In some embodiments, core layer 102 comprises a core glass composition, and first and/or second cladding layers 104 and 106 comprise a clad glass composition that is different than the core glass composition. The core glass composition and the clad glass composition are different from each other prior to subjecting the glass article to any type of chemical strengthening treatment as described herein. For example, in the embodiment shown in FIG. 3, core layer 102 comprises or is formed from a first glass composition, and each of first cladding layer 104 and second cladding layer 106 comprises or is formed from a second glass composition. In other embodiments, the first cladding layer 104 comprises or is formed from the second glass composition, and the second cladding layer 106 comprises or is formed from a third glass composition that is different than the first glass composition and the second glass composition.

[0023] The glass article 100 can be formed using a suitable process such as, for example, a fusion draw, down draw, slot draw, up draw, or float process. In some embodiments, the glass article 100 is formed using a fusion draw process. FIG. 4 is a cross-sectional view of one exemplary embodiment of an overflow distributor 200 that can be used to form a glass article such as, for example, glass article 100. Overflow distributor 200 can be configured as described in U.S. Patent No. 4,214,886, which is incorporated herein by reference in its entirety. For example, overflow distributor 200 comprises a lower overflow distributor 220 and an upper overflow distributor 240 positioned above the lower overflow distributor 220. Lower overflow distributor 220 comprises a trough 222. A first glass composition 224 is melted and fed into trough 222 in a viscous state. First glass composition 224 forms core layer 102 of glass article 100 as further described below. Upper overflow distributor 240 comprises a trough 242. A second glass composition 244 is melted and fed into trough 242 in a viscous state. Second glass composition 244 forms first and second cladding layers 104 and 106 of glass article 100 as further described below.

[0024] First glass composition 224 overflows trough 222 and flows down opposing outer forming surfaces 226 and 228 of lower overflow distributor 220. Outer forming surfaces 226 and 228 converge at a draw line 230. The separate streams of first glass composition 224 flowing down respective outer forming surfaces 226 and 228 of lower overflow distributor 220 converge at draw line 230 where they are fused together to form core layer 102 of glass article 100.

[0025] Second glass composition 244 overflows trough 242 and flows down opposing outer forming surfaces 246 and 248 of upper overflow distributor 240. Second glass composition 244 is deflected outward by upper overflow distributor 240 such that the second glass composition flows around lower overflow distributor 220 and contacts first glass composition 224 flowing over outer forming surfaces 226 and 228 of the lower overflow distributor. The separate streams of second glass composition 244 are fused to the respective separate streams of first glass composition 224 flowing down respective outer forming surfaces 226 and 228 of lower overflow distributor 220. Upon convergence of the streams of first glass composition 224 at draw line 230, second glass composition 244 forms first and second cladding layers 104 and 106 of glass article 100.

[0026] In some embodiments, a method comprises contacting first glass composition 224 of core layer 102 in the viscous state with second glass composition 244 of first and second cladding layers 104 and 106 in the viscous state to form the laminated sheet. In some of such embodiments, the laminated sheet is part of a glass ribbon traveling away from draw line 230 of lower overflow distributor 220 as shown in FIG. 4. The glass ribbon can be drawn away from lower overflow distributor 220 by a suitable means including, for example, gravity and/or pulling rollers. The glass ribbon cools as it travels away from lower overflow distributor 220. The glass ribbon is severed to separate the laminated sheet therefrom. Thus, the laminated sheet is cut from the glass ribbon. The glass ribbon can be severed using a suitable technique such as, for example, scoring, bending, thermally shocking, and/or laser cutting. In some embodiments, glass article 100 comprises the laminated sheet as shown in FIG. 3. In other embodiments, the laminated sheet can be processed further (e.g., by cutting or molding) to form glass article 100. [0027] Although glass article 100 shown in FIG. 3 comprises three layers, other embodiments are included in this disclosure. In other embodiments, a glass article can have a determined number of layers, such as four, five, or more layers. For example, a glass article comprising four layers can be formed using a lower overflow distributor with a divided trough so that two glass compositions flow over opposing outer forming surfaces of the lower overflow distributor and converge at the draw line. A glass article comprising five or more layers can be formed using additional overflow distributors and/or using overflow distributors with divided troughs. Thus, a glass article having a determined number of layers can be formed by modifying the overflow distributor accordingly.

[0028] Although glass article 100 shown in FIG. 3 comprises a laminated sheet, other embodiments are included in this disclosure. In other embodiments, a glass article comprises a laminated tube comprising multiple tubular layers (e.g., formed by one or more annular orifices). For example, a partial cross-section of the laminated tube comprises a laminate structure similar to that shown in FIG. 3. In other embodiments, a glass article comprises a shaped glass article (e.g., formed by shaping or molding a laminated sheet).

[0029] A thickness of glass article 100 can be measured as the distance between opposing outer surfaces (e.g., outer surfaces 108 and 110) of the glass article 100 as shown in FIG. 3.

In some embodiments, glass article 100 comprises a thickness of at least about 0.05 mm, at least about 0.1 mm, at least about 0.2 mm, or at least about 0.3 mm. Additionally, or alternatively, glass article 100 comprises a thickness of at most about 2 mm, at most about 1.5 mm, at most about 1 mm, at most about 0.7 mm, or at most about 0.5 mm. In some embodiments, a ratio of a thickness of core layer 102 to a thickness of glass article 100 is at least about 0.7, at least about 0.8, at least about 0.85, at least about 0.9, or at least about 0.95. Additionally, or alternatively, the ratio of the thickness of core layer 102 to the thickness of glass article 100 is at most about 0.95, at most about 0.93, at most about 0.9, at most about 0.87, or at most about 0.85. In some embodiments, a thickness of each of first cladding layer 104 and second cladding layer 106 is from about 0.01 mm to about 0.3 mm.

[0030] In some embodiments, the first glass composition of core layer 102 and/or the second glass composition of first cladding layer 104 and/or second cladding layer 106 comprise a liquidus viscosity of at least about 30 kiloPoise (kP), at least about 50 kP, at least about 100 kP, at least about 200 kP, or at least about 300 kP. In some embodiments, the first glass composition and/or the second glass composition comprise a liquidus viscosity suitable for forming glass article 100 using a fusion draw process as described herein. For example, the first glass composition of core layer 102 comprises a liquidus viscosity of at least about 60 kP, at least about 100 kP, at least about 200 kP, or at least about 300 kP. Additionally, or alternatively, the first glass composition comprises a liquidus viscosity of at most about 3500 kP at most about 3000 kP, at most about 2500 kP, at most about 1000 kP, or at most about 800 kP. Additionally, or alternatively, the second glass composition of first cladding layer 104 and/or second cladding layer 106 comprises a liquidus viscosity of at least about 50 kP, at least about 100 kP, or at least about 200 kP. Additionally, or alternatively, the second glass composition comprises a liquidus viscosity of at most about 3500 kP, at most about 3000 kP, at most about 2500 kP, at most about 1000 kP, or at most about 800 kP. The first glass composition can aid in carrying the second glass composition over the overflow distributor to form the second layer. Thus, the second glass composition can comprise a liquidus viscosity that is lower than generally considered suitable for forming a single layer sheet using a fusion draw process.

[0031] In some embodiments, glass article 100 is mechanically strengthened. For example, the second glass composition of first cladding layer 104 and/or second cladding layer 106 comprises a different coefficient of thermal expansion (CTE) than the first glass composition of core layer 102. As used herein, the term“coefficient of thermal expansion,” or“CTE,” refers to the average coefficient of thermal expansion unless otherwise indicated. Further, as used herein, the term“average coefficient of thermal expansion,” or“average CTE,” refers to the average coefficient of linear thermal expansion of a given material or layer between 0 °C and 300 °C. The measurement of CTE as given herein is in units of 1 O ⁷ / °C ¹ . The CTE can be determined, for example, using the procedure described in ASTM E228“Standard Test Method for Linear Thermal Expansion of Solid Materials With a Push-Rod Dilatometer” or ISO 7991 : 1987“Glass— Determination of coefficient of mean linear thermal expansion.”

[0032] Providing a CTE contrast between directly adjacent layers of glass article 100 can result in mechanical strengthening of the glass article. For example, first and second cladding layers 104 and 106 are formed from a glass composition (e.g., the second glass composition) having a lower CTE than a glass composition (e.g., the first glass composition) of core layer 102. Thus, glass article 100 comprises a CTE contrast CTEcore - CTEciad that is greater than zero. The relatively lower CTE of first and second cladding layers 104 and 106 compared to core layer 102 results in formation of compressive stress in the cladding layers and tensile stress in the core layer upon cooling of glass article 100. Thus, the difference between the CTE CTEcore of core layer 102 and the CTE CTEdad of first cladding layer 104 and/or second cladding layer 106, or CTE contrast CTEcore - CTEdad, produces compressive stress in the cladding layers, whereby glass article 100 is mechanically strengthened. In embodiments in which the cladding layers are exterior layers of the glass article, such compressive stress in the cladding layers can be beneficial for the strength of the glass article by resisting propagation of flaws present at the outer surface of the glass article. In various embodiments, each of the first and second cladding layers, independently, can have a higher CTE, a lower CTE, or substantially the same CTE as the core layer.

[0033] In some embodiments, the CTE of core layer 102 and the CTE of first cladding layer 104 and/or second cladding layer 106 differ by at least about lxlO^C ¹ , at least about 2xlO ^7o C ¹ , at least about SxlO^C ¹ , at least about dxlO^C ¹ , at least about SxlO^C ¹ , at least about lOxlO^C ¹ , at least about l5xlO ^7o C ¹ , at least about 20xl0 ^7o C ¹ , at least about 25x10^C ¹ , at least about SOxlO^C ¹ , at least about SSxlO^C ¹ , at least about 40x10^C ¹ , or at least about 45x10^C ¹ . Additionally, or alternatively, the CTE of core layer 102 and the CTE of first cladding layer 104 and/or second cladding layer 106 differ by at most about lOOxlO^C ¹ , at most about 75xlO ^7o C ¹ , at most about SOxlO^C ¹ , at most about dOxlO^C ¹ , at most about SOxlO^C ¹ , at most about 20xl0 ^7o C ¹ , at most about lOxlO^C ¹ , at most about at most about 8xlO ^7o C ¹ , at most about 7xlO ^7o C ¹ , at most about 6x10^C ¹ , or at most about 5xlO ^7o C ¹ . For example, in some embodiments, the CTE of core layer 102 and the CTE of first cladding layer 104 and/or second cladding layer 106 differ by about 1x10 ^C ¹ to about lOxlO^C ¹ or about lxlO^C ¹ to about SxlO^C ¹ . In some embodiments, the second glass composition of first cladding layer and/or second cladding layer comprises a CTE of at most about at most about 89xlO ^7o C ¹ , at most about ddcΐq ⁷ ^ ¹ , at most about 80xl0 ^7o C ¹ , at most about 70x 10 ^7o C ', at most about 60x 10 ^7o C ', at most about SOxlO^C ¹ , at most about dOxlO^C ¹ , or at most about SSxlO^C ¹ . Additionally, or alternatively, the second glass composition of first cladding layer 104 and/or second cladding layer 106 comprises a CTE of at least about lOxlO^C ¹ , at least about lSxlO^C ¹ , at least about 25x10^C ¹ , at least about 30xl0 ^7o C ¹ , at least about 40x10^C ¹ , at least about SOxlO^C ¹ , at least about όqcΐq ⁷ ^ ¹ , at least about 70xl0 ^7o C ¹ , at least about SOxlO^C ¹ , or at least about 85xlO ^o C' Additionally, or alternatively, the first glass composition of core layer 102 comprises a CTE of at least about dOxlO^C ¹ , at least about SOxlO^C ¹ , at least about at least about 65xlO ^7o C ¹ , at least about 70xl0 ^7o C ¹ , at least about dqcΐq ⁷ ^ ¹ , or at least about 90x l O ^C ¹ . Additionally, or alternatively, the first glass composition of core layer 102 comprises a CTE of at most about 120x 10 ^7o C ¹ , at most about 1 lOxlO ^C ¹ , at most about lOOxlO ^C ¹ , at most about 90x10 ^C ¹ , at most about 75xlO ^7o C ^l , or at most about TOxlO ^C ¹ .

[0034] In some embodiments, glass article 100 is chemically strengthened. For example, glass article 100 is subjected to an ion-exchange treatment to increase the compressive stress in a region of the glass article near exposed surfaces of the glass article. In some

embodiments, the ion-exchange treatment comprises applying an ion-exchange medium to one or more exposed surfaces of glass article 100. The ion-exchange medium comprises a solution, a paste, a gel, a liquid, a vapor, a plasma, or another suitable medium comprising larger ions to be exchanged with smaller ions in the glass matrix (e.g., the glass matrix of first cladding layer 104 and/or the second cladding layer 106). The terms“larger ions” and “smaller ions” are relative terms, meaning that the larger ions are relatively large compared to the smaller ions, and the smaller ions are relatively small compared to the larger ions. Thus, the larger ions have a larger ionic radius than the smaller ions, and the smaller ions have a smaller ionic radius than the larger ions. In some embodiments, core layer 102, first cladding layer 104, and/or second cladding layer 106 of glass article 100 comprise an alkali aluminosilicate glass. Thus, the smaller ions in glass article 100 and the larger ions in the ion exchange medium may be monovalent alkali metal cations (e.g., Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ , and/or Cs ⁺ ). Alternatively, monovalent cations in glass article 100 may be replaced with

monovalent cations other than alkali metal cations (e.g., Ag ⁺ or the like). In some

embodiments, core layer 102, first cladding layer 104, and/or second cladding layer 106 of glass article 100 comprise an alkaline earth aluminosilicate glass. Thus, the smaller ions in glass article 100 and the larger ions in the ion exchange medium may be divalent alkaline earth cations (e.g., Be ²⁺ , Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , and/or Ba ²⁺ ). In some embodiments, the ion-exchange medium comprises a molten salt solution, and the ion-exchange treatment comprises immersing the laminated glass article in a molten salt bath comprising larger ions (e.g., K ⁺ , Na ⁺ , Ba ²⁺ , Sr ²⁺ , and/or Ca ²⁺ ) to be exchanged with smaller ions (e.g., Na ⁺ , Li ⁺ , Ca ²⁺ , and/or Mg ²⁺ ) in the glass matrix. In some embodiments, the molten salt bath comprises a salt (e.g., a nitrate, a sulfate, and/or a chloride) of the larger ions. For example, the molten salt bath comprises molten KNCh, molten NaNCh, or a combination thereof. Additionally, or alternatively, the temperature of the molten salt bath is from about 380°C to about 450°C, and an immersion time is from about 2 hours to about 16 hours. [0035] By replacing smaller ions in the glass matrix with larger ions at exposed surfaces of glass article 100, the tensile stress of core layer 102 is reduced or eliminated or a compressive stress is formed near the exposed surface of the glass article. Additionally, or alternatively, the compressive stress of first cladding layer 104 and/or second cladding layer 106 is increased or generated near the exposed surface of glass article 100. For example, during the ion-exchange treatment, the larger ions from the ion-exchange medium diffuse into an outer portion of core layer 102 near the exposed surface of glass article 100, and the smaller ions from the glass matrix diffuse out of the outer portion of the core layer. Thus, the outer portion of core layer 102 comprises an ion-exchanged region of glass article 100. The increased concentration of the larger ions in the ion-exchanged region causes crowding of the glass matrix and decreases the tensile stress and/or generates compressive stress in the ion-exchanged region. Thus, the ion-exchanged region comprises a reduced tensile stress relative to the remainder (e.g., the non-ion-exchanged region) of core layer 102.

Additionally, or alternatively, during the ion-exchange treatment, the larger ions from the ion-exchange medium diffuse into an outer portion of first cladding layer 104 and/or second cladding layer 106 near the exposed surface of glass article 100, and the smaller ions from the glass matrix diffuse out of the outer portion of the first cladding layer and/or the second cladding layer. Thus, the outer portion of first cladding layer 104 and/or second cladding layer 106 comprises an ion-exchanged region of glass article 100. The increased

concentration of the larger ions in the ion-exchanged region causes crowding of the glass matrix and increases the compressive stress of glass article 100 in the ion-exchanged region. Thus, the ion-exchanged region comprises an increased compressive stress relative to the compressive stress of the remainder (e.g., the non-ion-exchanged region) of first cladding layer 104 and/or second cladding layer 106.

[0036] In some embodiments, glass article is mechanically strengthened as described herein (e.g., the CTE of first cladding layer 104 and/or second cladding layer 106 is lower than the CTE of core layer 102). In such embodiments, subjecting glass article 100 to the

ion-exchange treatment increases a surface compressive stress at the outer surface of the glass article (e.g., from an initial surface compressive stress generated by the CTE mismatch) to a final surface compressive stress. For example, the final compressive stress is at least about 200 MPa, at least about 300 MPa, at least about 400 MPa, at least about 500 MPa, at least about 600 MPa, at least about 700 MPa, at least about 800 MPa, at least about 900 MPa, or at least about 1000 MPa. Additionally, or alternatively, the final compressive stress value is at most about 1300 MPa, at most about 1200 MPa, at most about 1100 MPa, at most about 1000 MPa, at most about 900 MPa, or at most about 800 MPa.

[0037] Specifically, laminated glass articles generally comprise relatively high core tensile stresses due to the mismatch between CTEs of the core versus clad glass layers. For example, such laminated glass articles may have a maximum core tensile stress of about 57 MPa.

[0038] A laminated glass article 100 as described above provides the requisite mechanical properties for use as a LiDAR cover 18. In embodiments, each of the first cladding layer 104 and the second cladding layer 106 of the laminated glass article 100 has a thickness of greater than 40 pm, and in some embodiments, the thickness is up to 125 pm. In embodiments, the first cladding layer 104 and second cladding layer 106 provide compressive stresses throughout their depth by virtue of their lower CTEciad than the CTEcore of the core layer 102. The thickness of the first cladding layer 104 and the second cladding layer 106 provides enhanced scratch and abrasion resistance as will be demonstrated in the exemplary embodiments provided further below, especially as compared to conventional chemically and/or thermally strengthened glasses.

[0039] In other embodiments, the first cladding layer 104 and the second cladding layer 106 provide compressive stresses through at least a substantial portion of their thickness (e.g., at least 40 pm) by virtue of chemical or thermal tempering. In such embodiments, the CTEciad can be selected to further enhance the compressive properties of the first cladding layer 104 and the second cladding layer 106, e.g., by selecting a CTEciad that is lower than the CTEcore. However, in other such embodiments, the compressive properties of the first cladding layer 104 and the second cladding layer 106 are primarily derived from chemical and/or thermal tempering, not the difference in CTEciad and CTEcore, and the cladding composition of the first cladding layer 104 and the second cladding layer 106 are selected for another particular property, such as a particular optical or aesthetic property.

[0040] In the various embodiments described herein, the laminated glass article 100 comprises a compressive stress or a tensile stress at a given depth within or in a specific layer of the laminated glass article 100. Compressive stress and/or tensile stress values can be determined using, any suitable technique including, for example, a birefringence based measurement technique, a refracted near-field (RNF) technique, or a photoelastic measurement technique (e.g., using a polarimeter). Exemplary standards for stress measurement include, for example, ASTM C1422/C1422M - 10“Standard Specification for Chemically Strengthened Flat Glass” and ASTM F218“Standard Method for Analyzing Stress in Glass.”

[0041] Besides the mechanical properties, the laminated glass article 100 absorbs light in the visible spectrum (380 nm to 750 nm). In embodiments, at least the core composition of core layer 102 is chosen and/or configured to absorb light in the visible spectrum. In such embodiments, the first cladding layer 104 and/or the second cladding layer 106 may transmit light in the visible spectrum as long as it also transmits light in the infrared spectrum. The overall intended effect is that the laminated glass article 100 is configured to transmit light in the infrared spectrum. For example, in embodiments, the laminated glass article 100 transmits infrared light, e.g., between the wavelengths of 1000 nm to 2400 nm, between the wavelengths of 1200 nm to 2000 nm, or between the wavelengths of 1400 nm to 1600 nm. In specific embodiments, the core composition of core layer 102 is chose and/or configured to absorb light in the visible spectrum and to transmit light in the infrared spectrum, and the first cladding layer 104 and the second cladding layer 106 are chosen and/or configured to transmit both visible spectrum light and infrared spectrum light.

[0042] As used herein, to absorb light in a particular spectrum means to transmit less than 10% of such incident light through the thickness of a layer or article from a first surface to a second, opposing surface. In other embodiments, absorbing light in a particular spectrum means to transmit less than 5% of such incident light through the thickness of a layer or article from the first surface to the second, opposing surface. Further, as used herein, to transmit light in a particular spectrum means to transmit at least 70% of such incident light through the thickness of the layer or article from the first surface to the second, opposing surface. In other embodiments, to transmit light in a particular spectrum means to transmit at least 80% of such incident light through the thickness of the layer or article from the first surface to the second, opposing surface. In still other embodiments, to transmit light in a particular spectrum means to transmit at least 90% of such incident light through the thickness of the layer or article from the first surface to the second, opposing surface.

[0043] The ability of a glass layer to absorb or transmit light of a particular spectrum depends, for example, on the composition of the glass, the oxidation-reduction equilibria, etc. In embodiments, the inclusion of a transition metal in the glass composition will allow the glass composition to absorb light in the visible spectrum. In embodiments, the transition metal comprises up to 5 wt% of the glass composition. In a particular embodiment, the glass composition is a silicate glass composition, such as soda-lime glass, phosphosilicate glass, borosilicate glass, borophosphosilicate glass, aluminosilicate glass, barium-sodium-silicate glass, etc. Exemplary transition metals that can be added up to 5 wt% include Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, W, Rh, Ag, and Cd. Other elements that may be used to absorb visible light include S, Se, Pb, Bi, Ce, Pt, and U. Additionally, blends of certain elements can be used to absorb light in the visible spectrum. Exemplary blends include Cr and Mn, ZnSe, ZnS, Au halides (e.g., A CU), Bi and Sn, Ce02 and Ti02, UO3, Ni ²⁺ compounds (e.g., NiO), Ag halides (e.g., AgCl), FeO, and Cd-S-Se strike-in glasses. In embodiments, these elements and blends are added in an amount of up to 15 wt%.

[0044] Certain elements modify the oxidation states of the glass, resulting in the property of absorbing light in the visible spectrum. Such elements include As, Sn, Sb, and C. Further, reducing agents can be added to cause the glass to absorb visible light. Exemplary reducing agents include sulfides, phosphorous, ferro-phosphorous, metal phosphides, carbon, and halogens (e.g., F, Cl, Br, and I). In embodiments, each of the foregoing elements and reducing agents are present in amount of at most 5 wt%.

[0045] Exemplary glass compositions that are capable of transmitting light in the infrared spectrum and absorbing light in the visible spectrum are provided in Table 1.

Table 1. Composition of Exemplary Core Glass Materials

[0046] FIG. 5 provides a transmittance spectra for Core 1 for light between the wavelengths of 200 nm and 2400 nm. As can be seen, transmission of light in the visible spectrum is below 5%, and transmission of light above 1000 nm is greater than 80%. Further, from 1500 nm to 1600 nm, infrared light is transmitted at over 90%, which encompasses the wavelength of a 1550 nm LiDAR laser. FIG. 6 provides a transmittance spectra for Core 1, Core 2, and Core 3. As can be seen, the internal transmittance for each of Core 1, Core 2, and Core 3 is less than 0.1 over the visible spectrum. Further, above 1100 nm (i.e., in the infrared spectrum), the internal transmittance for each of Core 1, Core 2, and Core 3 is above 0.8.

[0047] Laminated glass articles 100 were made using a core layer 102 of an aluminosilicate glass and a first cladding layer 104 and a second cladding layer 106 of borosilicate glass. Table 2, below, provides the base glass compositions of core layer 102 and the cladding layers 104, 106. The base composition for the core layer 102 would be modified to include one of the aforementioned visible light absorbers or swapped for one of Cores 1-4; however, for the purposes of the mechanical surface testing of the cladding layers 104, 106 discussed below, the base glass compositions were used.

Table 2. Base Composition of Glass used in Exemplary Laminate Article

[0048] The glass laminated articles 100 were tested using abraded ring-on-ring (ARoR) testing. During ARoR testing, each sample was subjected to abrasion, and then the stress to failure (i.e., crack formation originating at the indent impression) was determined using ring- on-ring testing for each sample. Specifically, ARoR failure stresses obtained for glass samples were determined by first blasting the surface of the sample to be studied (dimensions are 50 mm x 50 mm x 0.6 mm thick) with 90 grit silicon carbide (SiC) at a pressure of from 5 psi to 25 psi for five seconds. The samples were masked so that the abrasion was limited to a 6 mm diameter circle located at the center of the 50 mm ^c 50 mm faces of the sample.

Abrasion of the samples was followed by ring-on-ring load to failure testing (as defined in ASTM C 1499-03) with a 1 inch diameter support ring and a ½ inch diameter loading ring. Each sample was placed on the support ring with the abraded side face down, so as to put the abraded region in tension during testing. The load was applied at a rate of 1.2 mm/min. Testing was performed at room temperature in 50% relative humidity. The radius of curvature on the rings was 1/16 inch.

[0049] FIG. 7 provides the results of the testing. As can be seen, the laminated glass articles 100 have a substantially constant fail stress of greater than 300 MPa and more specifically of about 380 MPa. The chemically strengthened glass initially has a higher ARoR fail stress, but as the abrasion pressure was increased, the fail stress dropped steeply. At 10 psi of abrasion pressure, the ARoR fail stress for the chemically strengthened glass was about 200 MPa, and at 25 psi of abrasion pressure, the ARoR fail stress fell below 100 MPa.

[0050] The parabolic change in the properties of the chemically strengthened glass in response to increasing abrasion pressure can also be seen with respect to surface defect analysis as shown in FIG. 8. During surface defect analysis, the glass test samples were subjected to the same abrasion procedure as described above, and then the surfaces of the samples were analyzed using image analysis software to determine the ratio of damaged surface to the total surface area of the sampled image. In FIG. 8, it can be seen that the chemically strengthened glass exhibits a parabolic increase in the amount of damaged surface area as the abrasion pressure increases from 4 psi to 20 psi. By comparison, the laminated glass articles 100 as described herein exhibit a substantially flatter curve in damaged surface area after exposure to abrasion pressure from 4 psi to 20 psi.

[0051] The better resistance of the laminated glass articles 100 to abrasion pressure indicates a better suitability for use as a LiDAR cover 18, especially on a vehicle where dust particles and other airborne abrasives contact the LiDAR cover 18 at high speed either from the vehicle’s travel speed or from being kicked up by another vehicle. Additionally, as demonstrated above, the laminated glass articles 100 provide the requisite infrared transmittance for sending and receiving LiDAR signals while also absorbing visible light for an aesthetically-pleasing deadfront to conceal the lasers and detectors.

[0052] 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. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is in no way intended that any particular order be inferred. In addition, as used herein, the article“a” is intended to include one or more than one component or element, and is not intended to be construed as meaning only one.

[0053] It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the disclosed embodiments. Since modifications, combinations, sub-combinations and variations of the disclosed embodiments incorporating the spirit and substance of the embodiments may occur to persons skilled in the art, the disclosed embodiments should be construed to include everything within the scope of the appended claims and their equivalents.