Glass compositions having high thermal and chemical stability and methods of making thereof
AssigneeCorning Incorporated
InventorsPaul S. Danielson, Adam J.G. Ellison, Natesan Venkataraman
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Abstract
Described herein are alkali-free, boroalumino silicate glasses exhibiting desirable physical and chemical properties for use as substrates in flat panel display devices, such as, active matrix liquid crystal displays (AMLCDs). In accordance with certain of its aspects, the glasses possess good dimensional stability as a function of temperature.
Claims20
An alkali-free glass comprising in mole percent on an oxide basis:
- SiO2
- 64.0–72.0
- Al2O3
- 9.0–16.0
- B2O3
- 1.0–5.0
- MgO + La2O3
- 1.0–7.5
- CaO
- 2.0–7.5
- SrO
- 0.0–4.5
- BaO
- 1.0–7.0
- wherein Σ(MgO+CaO+SrO+BaO+3La2O3)/(Al2O3)≧1.15, where Al2O3, MgO, CaO, SrO, BaO, and La2O3 represent the mole percents of the respective oxide components.
An alkali-free glass comprising in mole percent on an oxide basis:
- SiO2
- 65.0–71.0
- Al2O3
- 9.0–16.0
- B2O3
- 1.5–4.0
- MgO + La2O3
- 0.5–7.5
- CaO
- 2.0–6.0
- SrO
- 0.0–4.5
- BaO
- 1.0–7.0
- La2O3
- >0.0 and less than or equal to 4.0
- wherein Σ(MgO+CaO+SrO+BaO+3La2O3)/(Al2O3)≧1.2, where Al2O3, MgO, CaO, SrO, BaO, and La2O3 represent the mole percents of the respective oxide components.
An alkali-free glass comprising SiO2, Al2O3, B2O3, MgO, CaO, and at least one of SrO and BaO, wherein the glass' composition satisfies the relationship:
- [MgO]:[CaO]:[SrO+BaO]=1±0.15:1±0.15:1±0.15
- where [MgO], [CaO], and [SrO+BaO] are the concentrations of the indicated components of the glass in mole percent on an oxide basis.
A method for producing alkali-free glass sheets by a downdraw process comprising selecting, melting, and fining batch materials so that the glass making up the sheets comprises SiO2, Al2O3, B2O3, MgO, CaO and BaO, and, on an oxide basis, comprises:
- (i) a MgO content greater than or equal to 2.0 mole percent;
- (ii) a CaO content greater than or equal to 3.0 mole percent;
- and
- (iii) a BaO content greater than or equal to 1.0 mole percent, wherein:
- (a) the glass has a Σ(MgO+CaO+SrO+BaO)/(Al2O3) ratio greater than or equal to 1.15, where Al2O3, MgO, CaO, SrO, and BaO represent the mole percents of the respective oxide components;
- (b) the fining is performed without the use of substantial amounts of arsenic;
- and
- (c) a population of 50 sequential glass sheets produced by the downdraw process from the melted and fined batch materials has an average gaseous inclusion level of less than 0.10 gaseous inclusions/cubic centimeter, where each sheet in the population has a volume of at least 500 cubic centimeters.
Dependencies are inferred from the claim text.