Computer-implemented methods and apparatus are provided for predicting/estimating (i) a non-equilibrium viscosity for at least one given time point in a given temperature profile for a given glass composition, (ii) at least one temperature profile that will provide a given non-equilibrium viscosity for a given glass composition, or (iii) at least one glass composition that will provide a given non-equilibrium viscosity for a given time point in a given temperature profile. The methods and apparatus can be used to predict/estimate stress relaxation in a glass article during forming as well as compaction, stress relaxation, and/or thermal sag or thermal creep of a glass article when the article is subjected to one or more post-forming thermal treatments.

Embodiments disclosed therein generally pertain to selectively strengthening glass. More particularly, techniques are described for selectively strengthening cover glass, which tends to be thin, for electronic devices, namely, portable electronic devices.

A glass plate strengthening device includes: a work furnace including a preheating furnace, and a strengthening furnace below the preheating furnace; a transport module configured to transport a glass plate between the preheating furnace and the strengthening furnace in the work furnace; a separator between the preheating furnace and the strengthening furnace, configured to enter and exit the work furnace, and configured to separate or integrate the preheating furnace and the strengthening furnace during entering and exiting; a door module including a door part on a side wall of the work furnace, and configured to provide an entrance space through the door part during the entering and exiting of the separator; and a shield coupled to an outer wall of the work furnace to be adjacent to the door module, and configured to block the entrance space from an external space.

A cover glass of the present invention is characterized by including in a glass composition at least three or more components selected from SiO.sub.2, Al.sub.2O.sub.3, B.sub.2O.sub.3, Li.sub.2O, Na.sub.2O, K.sub.2O, MgO, CaO, BaO, TiC.sub.2, Y.sub.2O.sub.3, ZrO.sub.2, and P.sub.2O.sub.5, and having an X value of 7, 400 or more calculated by the following equation. The X value is a value calculated by the equation

X=61.1×[SiO.sub.2]+174.3×[Al.sub.2O.sub.3]+11.3×[B.sub.2O.sub.3]+124.7×[Li.sub.2O]−5.2×[Na.sub.2O]+226.7×[K.sub.2O]+139.4×[MgO]+117.5×[CaO]+89.6×[BaO]+191.8×[TiO.sub.2]+226.7×[Y.sub.2O.sub.3]+157.9×[ZrO.sub.2]−42.2×[P.sub.2O.sub.5].

A method of etching a substrate comprises: contacting a substrate having a thickness with an etchant disposed in a vessel for a period of time until the thickness has reduced by at least 2 μm and at an average rate of 1 μm per minute to 6.7 μm per minute, the etchant having a temperature of 170° C. to 300° C. and comprising a molten mixture of two or more alkali hydroxides; and ceasing contacting the substrate with the etchant. The etchant in some instances comprises a molten mixture of NaOH and KOH. For example, the etchant in some instances includes a molten mixture of 24 wt. % to 72 wt. % NaOH, and 76 wt. % to 28 wt. % KOH. In some instances, the method alters the weight percentage of Na.sup.+, K.sup.+ and Li.sup.+ in the composition of the surface of the substrate by less than 1%.

Embodiments disclosed therein generally pertain to selectively strengthening glass. More particularly, techniques are described for selectively strengthening cover glass, which tends to be thin, for electronic devices, namely, portable electronic devices.

An ion exchange tank is provided. The ion exchange tank includes a processing chamber and an additive chamber separated by a weir system, the weir system having a flow channel fluidly connecting the processing chamber to the additive chamber, wherein the flow is divided from the additive chamber by a first partition and divided from the processing chamber by a second partition, wherein the additive chamber comprises a solids-absorbing material disposed therein.

A glass-ceramic includes glass and crystalline phases, where the crystalline phase includes non-stoichiometric suboxides of titanium, forming ‘bronze’-type solid state defect structures in which vacancies are occupied with dopant cations.

Methods are provided for measuring the asymmetry of glass-sheet manufacturing processes. The methods include subjecting glass sheets or test samples taken from glass sheets to an ion-exchange process and measuring warp values. Metrics for the asymmetry of the glass-sheet manufacturing process are then obtained from the warp values. In one embodiment, the metric is independent of the geometry of the glass sheets or the test samples (the BM.sub.1 metric); in another embodiment, the metric is independent of the geometry of the glass sheets or the test samples and substantially independent of the ion-exchange process used in the testing (the ASYM metric).

A stress-engineered frangible structure includes multiple discrete glass members interconnected by inter-structure bonds to form a complex structural shape. Each glass member includes strengthened (i.e., by way of stress-engineering) glass material portions that are configured to transmit propagating fracture forces throughout the glass member. Each inter-structure bond includes a bonding member (e.g., glass-frit or adhesive) connected to weaker (e.g., untreated, unstrengthened, etched, or thinner) glass member region(s) disposed on one or both interconnected glass members that function to reliably transfer propagating fracture forces from one glass member to other glass member. An optional trigger mechanism generates an initial fracture force in a first (most-upstream) glass member, and the resulting propagating fracture forces are transferred by way of inter-structure bonds to all downstream glass members. One-way crack propagation is achieved by providing a weaker member region only on the downstream side of each inter-structure bond.