Glasses and glass ceramics including a metal oxide concentration gradient

#The disclosure relates to glass-based articles exhibiting improved damage resistance, including improved fracture resistance, and more particularly to glass and glass ceramic articles exhibiting a non-zero metal oxide concentration gradient or concentration that varies along a substantial portion of the thickness.

#Glass-based articles often experience severe impacts that can introduce large flaws into a surface of such articles. Such flaws may extend to depths of up to about 200 micrometers from the surface. Traditionally, thermally tempered glass has been used to prevent failures where such flaws may be introduced to the glass because thermally tempered glass often exhibits large compressive stress (CS) layers (e.g., approximately 21% of the total thickness of the glass), which can prevent flaws from propagating and thus, failure. An example of a stress profile generated by thermal tempering is shown in FIG. 1. In FIG. 1, the thermally treated glass-based article 100 includes a first surface 101, a thickness t1, and a surface CS 110. The glass-based article 100 exhibits a CS that decreases from the first surface 101 to a depth of layer (DOL) 130, as defined herein, at which depth the stress changes from compressive to tensile stress and reaches a maximum central tension (CT) 120.

#Thermal tempering is currently limited to thick glass-based articles (i.e., glass-based articles having a thickness t1 of about 3 millimeters or greater) because, to achieve the thermal strengthening and the desired residual stresses, a sufficient thermal gradient must be formed between the core of such articles and the surface. Such thick articles are undesirable or not practical in many applications such as displays (e.g., consumer electronics, including mobile phones, tablets, computers, navigation systems, and the like), architecture (e.g., windows, shower panels, countertops etc.), transportation (e.g., automotive, trains, aircraft, sea craft, etc.), appliances, or any application that requires superior fracture resistance but thin and light-weight articles.

#FIG. 1 is a cross-sectional view across a thickness of a known thermally tempered glass-based article;

#FIG. 2 is a cross-sectional view across a thickness of a known chemically strengthened glass-based article;

#FIG. 3 is a cross-sectional view across a thickness of a chemically strengthened glass-based article according to one or more embodiments of this disclosure;

#Reference will now be made in detail to various embodiments, examples of which are illustrated in the accompanying examples and drawings.

#In the following description, like reference characters designate like or corresponding parts throughout the several views shown in the figures. It is also understood that, unless otherwise specified, terms such as “top,” “bottom,” “outward,” “inward,” and the like are words of convenience and are not to be construed as limiting terms. In addition, whenever a group is described as comprising at least one of a group of elements and combinations thereof, it is understood that the group may comprise, consist essentially of, or consist of any number of those elements recited, either individually or in combination with each other. Similarly, whenever a group is described as consisting of at least one of a group of elements or combinations thereof, it is understood that the group may consist of any number of those elements recited, either individually or in combination with each other. Unless otherwise specified, a range of values, when recited, includes both the upper and lower limits of the range as well as any ranges therebetween. As used herein, the indefinite articles “a,” “an,” and the corresponding definite article “the” mean “at least one” or “one or more,” unless otherwise specified. It also is understood that the various features disclosed in the specification and the drawings can be used in any and all combinations.

#As used herein, the terms “glass-based article” and “glass-based substrates” are used in their broadest sense to include any object made wholly or partly of glass. Glass-based articles include laminates of glass and non-glass materials, laminates of glass and crystalline materials, and glass-ceramics (including an amorphous phase and a crystalline phase). Unless otherwise specified, all compositions are expressed in terms of mole percent (mol %).