GLASS ARTICLES AND METHOD FOR MAKING THEREOF
A glass composition is characterized by having little batch-to-batch variations in the properties of the glass products made thereof. The glass composition contains 40 to 99 wt. % SiO 2 with a softening temperature ranging from 600° C. to 1650° C., and wherein the standard deviation of softening temperature measurements obtained from 10 or more randomly selected samples of glass articles produced from the lot is 10° C. or less.
1 . A glass composition comprising a lot of glass articles, the glass composition containing 40 to 99 wt. % SiO 2 , wherein the glass composition has a softening temperature ranging from 600° C. to 1650° C. and a standard deviation σ of less 10° C. when the softening temperature is measured from 10 or more randomly selected samples of glass articles in the lot.
2 . The glass composition of claim 1 , wherein the standard deviation σ of the softening temperature is 5° C. or less, as measured from 10 or more randomly selected samples of glass articles in the lot.
3 . The glass composition of claim 1 , wherein the glass composition contains 90 to 95 wt. % SiO2, wherein the glass composition has an annealing temperature in the range of 1000-1250° C. and a standard deviation σ of less than 10° C. when the annealing temperature is measured from 10 or more randomly selected samples of glass articles in the lot.
4 . The glass composition of claim 1 , wherein the standard deviation σ of the annealing temperature is 5° C. or less, as measured from 10 or more randomly selected samples of glass articles in the lot.
5 . The glass composition of claim 1 , wherein the glass composition has an OH— concentration of less than 100 ppm, and a standard deviation σ of less than 10 ppm when the OH concentration is measured from 10 or more randomly selected samples of glass articles in the lot.
6 . The glass composition of claim 1 , wherein the glass composition has an OH— concentration of less than 50 ppm, and a standard deviation σ of less than 5 ppm when the OH concentration is measured from 10 or more randomly selected samples of glass articles in the lot.
7 . The glass composition of claim 6 , wherein the glass composition has an OH— concentration of less than 30 ppm, and a standard deviation σ of less than 5 ppm when the OH concentration is measured from 10 or more randomly selected samples of glass articles in the lot.
8 . The glass composition of claim 7 , wherein the glass composition has an OH— concentration of less than 20 ppm, and a standard deviation σ of less than 3 ppm when the OH concentration is measured from 10 or more randomly selected samples of glass articles in the lot.
9 . The glass composition of claim 1 , wherein the glass articles are processed from a standardized process having a process capability CpK of >1.33.
10 . The glass composition of claim 9 , wherein the glass articles are processed from a standardized process having a process capability CpK of >1.50.
11 . The glass composition of claim 1 , wherein the composition comprises 40 to 99 wt. % of SiO 2 , 0.1-25 wt. % of at least a dopant selected from the metal oxide group of Al 2 O 3 , CeO 2 , TiO 2 , Nd 2 O 3 , B 2 O 3 , CeO 2 , BaO, SrO, CaO, MgO, Na 2 O, K 2 O, Li 2 O, Sb 2 O 3 , and mixtures thereof, and 0.02 to 0.50 wt. % of a fumed metal oxide having a BET of 50-400 m 2 /g and a mean particle size of <1 μm, and wherein the fumed metal oxide is SiO 2 or a metal oxide present in the dopant.
12 . The glass composition of claim 11 , wherein the composition comprises 0.04 to 0.30 wt. % of the fumed metal oxide.
13 . The glass composition of claim 12 , wherein the composition comprises 0.05 to 0.15 wt. % of the fumed metal oxide.
14 . The glass composition of claim 11 , wherein the fumed metal oxide is first mixed with 20 to 100% of the at least a dopant forming a master batch, which is subsequently added to the SiO 2 of the glass composition.
15 . The glass composition of claim 1 , wherein the composition comprises 90 to 99 wt. % of SiO 2 and 0.1-8 wt. % of a dopant selected from the metal oxide group of Al 2 O 3 , CeO 2 , TiO 2 , Nd 2 O 3 , B 2 O 3 , CeO 2 , BaO, SrO, CaO, MgO, Na 2 O, K 2 O, Li 2 O, Sb 2 O 3 , and mixtures thereof
16 . A process for making a glass product with reduced variations in its properties, the process comprises the steps of:
providing 40 to 99 wt. % of SiO 2 and 0.1-25 wt. % of at least a dopant selected from the metal oxide group of Al 2 O 3 , CeO 2 , Nd 2 O 3 , B 2 O 3 , CeO 2 , TiO 2 , BaO, SrO, CaO, MgO, Na 2 O, K 2 O, Li 2 O, Sb 2 O 3 , and mixtures thereof, wherein the dispersant is a fumed metal oxide having a BET of 50-400 m 2 /g and a mean particle size of <1 μm, and wherein the fumed metal oxide is SiO 2 or a metal oxide present in the dopant;
forming a first blend of 0.02 to 0.50 wt. % of a dispersant with 20% to 100% of the at least a dopant;
blending the first blend into the SiO 2 and any remainder of the at least a dopant forming a mixture;
producing a melt of molten glass from the mixture;
passing the molten glass along a tool to form a glass product, wherein the quartz product is in the form of a tubing, a rod, a blank, a strand, and wherein the wt. % is based on the total weight of the final mixture.
17 . The process of claim 16 , wherein the first blend is formed by mixing 0.04 to 0.30 wt. % of the dispersant with 0.1-8 wt. % of a dopant selected from the metal oxide group of Al 2 O 3 , CeO 2 , Nd 2 O 3 , B 2 O 3 , CeO 2 , BaO, SrO, CaO, MgO, TiO 2 , Na 2 O, K 2 O, Li 2 O, Sb 2 O 3 , and mixtures thereof,
18 . The process of claim 17 , wherein the first blend is formed by mixing 0.05 to 0.15 wt. % of the dispersant with 0.1-8 wt. % of a dopant selected from the metal oxide group of Al 2 O 3 , CeO 2 , Nd 2 O 3 , B 2 O 3 , CeO 2 , BaO, SrO, CaO, MgO, TiO 2 , Na 2 O, K 2 O, Li 2 O, Sb 2 O 3 , and mixtures thereof,
19 . The process of claim 16 , wherein the step of blending the first blend into 40 to 99 wt. % of SiO 2 forming a mixture further includes blending the first blend and the 40 to 99 wt. % of SiO 2 with 0.1-8 wt. % of a dopant selected from the metal oxide group of Al 2 O 3 , CeO 2 , Nd 2 O 3 , B 2 O 3 , CeO 2 , BaO, SrO, CaO, MgO, TiO 2 , Na 2 O, K 2 O, Li 2 O, Sb 2 O 3 , and mixtures thereof.
20 . A quartz glass product, comprising 40 to 99 wt. % of SiO 2 , 0.1-25 wt. % of at least a dopant selected from the metal oxide group of Al 2 O 3 , CeO 2 , Nd 2 O 3 , B 2 O 3 , CeO 2 , BaO, TiO 2 , SrO, CaO, MgO, Na 2 O, K 2 O, Li 2 O, Sb 2 O 3 , and mixtures thereof, and 0.04 to 0.30 wt. % of a fumed metal oxide having a BET of 50-400 m 2 /g and a mean particle size of <1 μm, and wherein the fumed metal oxide is SiO 2 or a metal oxide present in the dopant, and wherein the fumed metal oxide is first blended with 20-100% of the at least a dopant forming a master batch prior to blending with 40 to 99 wt. % of SiO 2 and any remainder of the at least a dopant.