Glass-ceramic with specific thermal expansion behavior

Claim 2

A transparent self-supporting, substantially homogeneous glass-ceramic body containing h-quartz solid solution crystals throughout, wherein a. the expression based on the difference between the maximal Δl/l value and the minimal value Δl/l, ##EQU4## within the temperature range between -50° C. and +100° C., is ≦1×10 -5 , b. the linear thermal expansion coefficient within the temperature range between 0° C. and +50° C. α0/50 has an absolute value ≦0.1×10 -6 /K, and c. ##EQU5## has a value ≦0.1×10 -5 , wherein l is the length, rate 1 is 6° C./hr from 350° C. to 20° C. and rate 2 is that of air quenching from 350° C. to 20° C., consisting essentially of in weight %: SiO 2 : 50.0-65.0 Al 2 O 3 : 18.0-27.0 B 2 O 3 : 0-1.0 P 2 O 5 : 0-10.0 Li 2 O: 2.5-4.0 Na 2 O: 0-2.0 K 2 O: 0-2.0 MgO: 0-0.5 ZnO: 1.0-5.0 CaO: 0-4.0 BaO: 1.0-5.0 TiO 2 : 0-5.0 ZrO 2 : 0-3.0 As 2 O 3 : 0-1.5 or Sb 2 O 3 : and having sufficient nucleating agents to form crystallites throughout the body.

Claim 3

A glass-ceramic of claim 1 essentially free of MgO.

Claim 4

A glass-ceramic of claim 1 consisting essentially of 0-0.10 wt. % MgO.

Claim 5

A glass-ceramic of claim 1 wherein V A is ≦1310° C.

Claim 6

A glass-ceramic of claim 1 wherein the total amount of SiO 2 +Al 2 O 3 +P 2 O 5 is about 83-87 Wt. %.

Claim 7

A glass-ceramic of claim 5 wherein V A is ≦1310° C.

Claim 8

A glass-ceramic of claim 1 essentially free of K 2 O.

Claim 9

A glass-ceramic of claim 1 prepared by heat treating the base glass composition at a rate of about 4° C./min up to about 730° C., maintaining it at about that temperature for about 1 hr, further heating it at a rate of about 4° C./hr up to about 850° C., maintaining it at about 1.5 h at that temperature and cooling to room temperature by turning off the source of heat.

Claim 10

A glass-ceramic of claim 2 essentially free of K 2 O.

Claim 11

A glass-ceramic of claim 1 wherein the amount of TiO 2 is at least 1.9 wt.% and of ZrO 2 at least 1.4 wt.%.

Claim 12

A glass ceramic of claim 9 wherein the amount of TiO 2 is at least 1.9 wt.% and of ZrO 2 at least 1.4 wt.%.

Claim 13

A glass ceramic of claim 10 wherein the amount of TiO 2 is at least 2.3 wt.%.

Claim 14

A glass ceramic of claim 11 wherein the amount of TiO 2 is at least 2.3 wt.%.

Claim 15

A glass-ceramic according to claim 1, consisting essentially of, in weight %: SiO 2 : 53.0-63.0 Al 2 O 3 : 20.0-24.0 P 2 O 5 : 0-8.0 SiO 2 +Al 2 O 3 +P 2 O 5 : 83.0-87.0 Li 2 O: 2.5-4.0 K 2 O+Na 2 O: 0-1.5 ZnO: 1.5-3.5 CaO: 0-2.0 BaO: 1.0-3.0 TiO 2 : 0-3.0 ZrO 2 : 0-2.0 As 2 O 3 : 0-1.0.

Claim 16

A transparent glass-ceramic containing h-quartz solid solution crystals, wherein a. the expression based on the difference between the maximal Δ1/1 value and the minimal value Δ1/1, ##EQU6## within the temperature range between -50° C. and +100° C., is ≦1×10 -5 , b. the linear thermal expansion coefficient within the temperature range between 0° C. and +50° C. α0/50, has an absolute value ≦0.1×10 -6 /K, and c. ##EQU7## has a value ≦0.1×10 -5 , wherein l is the length, rate 1 is 6° C./hr from 350° C. to 20° C. and rate 2 is that of air quenching from 350° C. to 20° C., consisting essentially of in weight %: SiO 2 : 50.0-65.0 Al 2 O 3 : 18.0-27.0 B 2 O 3 : 0-1.0 P 2 O 5 : 0-10.0 Li 2 O: 2.5-4.0 Na 2 O: 0-2.0 K 2 O: 0-2.0 MgO: 0-0.5 ZnO: 1.0-5.0 CaO: 0-4.0 BaO: 1.0-5.0 TiO 2 : 1.9-5.0 ZrO 2 : 1.4-3.0 As 2 O 3 : 0-1.5 or Sb 2 O 3 .

Claim 17

A transparent glass-ceramic containing h-quartz solid solution crystals, wherein a. the expression based on the difference between the maximal Δ1/1 value and the minimal value Δ1/1, ##EQU6## within the temperature range between -50° C. and +100° C., is ≦1×10 -5 , b. the linear thermal expansion coefficient within the temperature range between 0° C. and +50° C. α0/50, has an absolute value ≦0.1×10 -6 /K, and c. ##EQU7## has a value ≦0.1×10 -5 , wherein l is the length, rate 1 is 6° C./hr from 350° C. to 20° C. and rate 2 is that of air quenching from 350° C. to 20° C., consisting essentially of in weight %: SiO 2 : 50.0-65.0 Al 2 O 3 : 18.0-27.0 B 2 O 3 : 0-1.0 P 2 O 5 : 0-10.0 Li 2 O: 2.5-4.0 Na 2 O: 0-2.0 K 2 O: 0-2.0 MgO: 0-0.5 ZnO: 1.0-5.0 CaO: 0-4.0 BaO: 1.0-5.0 TiO 2 : 1.9-5.0 ZrO 2 : 1.4-3.0 As 2 O 3 : 0-1.5 or Sb 2 O 3 .

Claim 18

A transparent glass-ceramic containing h-quartz solid solution crystals, wherein a. the expression based on the difference between the maximal Δ1/1 value and the minimal value Δ1/1, ##EQU8## within the temperature range between -50° C. and +100° C., is ≦1×10 -5 , b. the linear thermal expansion coefficient within the temperature range between 0° C. and +50° C. α0/50, has an absolute value ≦0.1×10 -6 /K, and c. ##EQU9## has a value ≦0.1×10 -5 , wherein l is the length, rate 1 is 6° C./hr from 350° C. to 20° C. and rate 2 is that of air quenching from 350° C. to 20° C., consisting essentially of in weight %: SiO 2 : 50.0-65.0 Al 2 O 3 : 18.0-27.0 B 2 O 3 : 0-1.0 P 2 O 5 : 0-10.0 Li 2 O: 2.5-4.0 Na 2 O: 0-2.0 K 2 O: 0-2.0 MgO: 0-0.5 ZnO: 1.0-5.0 CaO: 0-4.0 BaO: 1.0-5.0 TiO 2 : 0-5.0 ZrO 2 : 0-3.0 As 2 O 3 : 0-1.5 or Sb 2 O 3 and wherein the minimum total of TiO 2 and ZrO 2 is 3.0 weight %.

Claim 19

A transparent glass-ceramic containing h-quartz solid solution crystals, wherein a. the expression based on the difference between the maximal Δ1/1 value and the minimal value Δ1/1, ##EQU8## within the temperature range between -50° C. and +100° C., is ≦1×10 -5 , b. the linear thermal expansion coefficient within the temperature range between 0° C. and +50° C. α0/50, has an absolute value ≦0.1×10 -6 /K, and c. ##EQU9## has a value ≦0.1×10 -5 , wherein l is the length, rate 1 is 6° C./hr from 350° C. to 20° C. and rate 2 is that of air quenching from 350° C. to 20° C., consisting essentially of in weight %: SiO 2 : 50.0-65.0 Al 2 O 3 : 18.0-27.0 B 2 O 3 : 0-1.0 P 2 O 5 : 0-10.0 Li 2 O: 2.5-4.0 Na 2 O: 0-2.0 K 2 O: 0-2.0 MgO: 0-0.5 ZnO: 1.0-5.0 CaO: 0-4.0 BaO: 1.0-5.0 TiO 2 : 0-5.0 ZrO 2 : 0-3.0 As 2 O 3 : 0-1.5 or Sb 2 O 3 and wherein the minimum total of TiO 2 and ZrO 2 is 3.0 weight %.

Claim 20

A glass-ceramic according to claim 16 wherein the minimum total of TiO 2 and ZrO 2 is 3.3 weight %.

Claim 21

A glass ceramic according to claim 16, which is a glass-ceramic body containing h-quartz solid solution crystals throughout.

Claim 22

A glass-ceramic according to claim 16, consisting essentially of, in weight %: SiO 2 : 53.0-63.0 Al 2 O 3 : 20.0-24.0 P 2 O 5 : 0-8.0 SiO 2 +Al 2 O 3 +P 2 O 5 : 83.0-87.0 Li 2 O: 2.5-4.0 K 2 O+Na 2 O: 0-1.5 ZnO: 1.5-3.5 CaO: 0-2.0 BaO: 1.0-3.0 TiO 2 : 0-3.0 ZrO 2 : 0-2.0 As 2 O 3 : 0-1.0.

Claim 23

A glass according to claim 16, a species of which being produced by the following steps: (i) Selecting a composition from the state ranges of SiO 2 , Al 2 O 3 and P 2 O 5 (ii) Varying the amount of at least one component from the group Li 2 O, ZnO, CaO, BaO to adjust the α 0/50 -value to a value lower than 0.1×10 -6 /K; (iii) Exchanging Al 2 O 3 against P 2 O 5 so as to obtain a linearization of the Δ1/1-curve.; (iv) If necessary, slightly varying other components of the composition thus obtained to compensate for an undesirable minor increase of the absolute value of α 0/50 .

Claim 24

A transparent glass-ceramic containing h-quartz solid solution crystals, wherein a. the expression based on the difference between the maximal Δ1/1 value and the minimal value Δ1/1 ##EQU10## within the temperature range between -50° C. and +100° C., is ≦0.1×10 -5 , b. the linear thermal expansion coefficient within the temperature range between 0° C. and +50°, α 0/50 , has an absolute value ≦0.1×10 -6 /K, and c. ##EQU11## has a value ≦0.1×10 -5 , wherein l is the length, rate 1 is 6°/hr. from 350° C. to 20° C. and rate 2 is that of air quenching from 350° C. to 20° C., consisting essentially of in weight %: SiO 2 : 57.0-59.0 Al 2 O 3 : 21.5-23.5 P 2 O 5 : 4.5-5.5 Li 2 O: 3.3-3.7 Na 2 O: 0.80-1.0 ZnO: 1.7-2.1 CaO: 1.8-2.0 BaO: 2.4-2.6 TiO 2 : 1.8-2.2 ZrO 2 : 1.5-1.9 As 2 O 3 : 0.40-0.80 and wherein the minimum total of TiO 2 and ZrO 2 is 3.0 wt. %.

Claim 25

A transparent glass-ceramic containing h-quartz solid solution crystals, wherein a. the expression based on the difference between the maximal Δ1/1 value and the minimal value Δ1/1 ##EQU10## within the temperature range between -50° C. and +100° C., is ≦0.1×10 -5 , b. the linear thermal expansion coefficient within the temperature range between 0° C. and +50°, α 0/50 , has an absolute value ≦0.1×10 -6 /K, and c. ##EQU11## has a value ≦0.1×10 -5 , wherein l is the length, rate 1 is 6°/hr. from 350° C. to 20° C. and rate 2 is that of air quenching from 350° C. to 20° C., consisting essentially of in weight %: SiO 2 : 57.0-59.0 Al 2 O 3 : 21.5-23.5 P 2 O 5 : 4.5-5.5 Li 2 O: 3.3-3.7 Na 2 O: 0.80-1.0 ZnO: 1.7-2.1 CaO: 1.8-2.0 BaO: 2.4-2.6 TiO 2 : 1.8-2.2 ZrO 2 : 1.5-1.9 As 2 O 3 : 0.40-0.80 and wherein the minimum total of TiO 2 and ZrO 2 is 3.0 wt. %.

Claim 26

A transparent, self-supporting, substantially homogenous glass-ceramic body containing h-quartz solid solution crystals throughout, wherein a. the expression based on the difference between the maximal Δ1/1 value and the minimal value Δ1/1, ##EQU12## within the temperature range between -50° C. and +100° C., is ≦0.1×10 -5 , b. the linear thermal expansion coefficient within the temperature range between 0° C. and +50°, α 0/50 , has an absolute value ≦0.1×10 -6 /K, and c. ##EQU13## has a value ≦1.0×10 -5 , wherein l is the length, rate 1 is 6°/hr from 350° C. to 20° C. and rate 2 is that of air quenching from 350° C. to 20° C., consisting essentially of in weight %: SiO 2 : 50.0-65.0 Al 2 O 3 : 18.0-27.0 B 2 O 3 : 0-1.0 Li 2 O: 2.5-4.0 Na 2 O: 0-2.0 K 2 O: 0-2.0 MgO: 0-0.5 ZnO: 1.0-5.0 CaO: 0-4.0 BaO: 1.0-5.0 TiO 2 : 0-5.0 ZrO 2 : 0-3.0 As 2 O 3 : 0-1.5 or Sb 2 O 3 and having sufficient nucleating agents to form crystallites throughout the body and P 2 O 5 is present.

Claim 27

A transparent, self-supporting, substantially homogenous glass-ceramic body containing h-quartz solid solution crystals throughout, wherein a. the expression based on the difference between the maximal Δ1/1 value and the minimal value Δ1/1, ##EQU12## within the temperature range between -50° C. and +100° C., is ≦0.1×10 -5 , b. the linear thermal expansion coefficient within the temperature range between 0° C. and +50°, α 0/50 , has an absolute value ≦0.1×10 -6 /K, and c. ##EQU13## has a value ≦1.0×10 -5 , wherein l is the length, rate 1 is 6°/hr from 350° C. to 20° C. and rate 2 is that of air quenching from 350° C. to 20° C., consisting essentially of in weight %: SiO 2 : 50.0-65.0 Al 2 O 3 : 18.0-27.0 B 2 O 3 : 0-1.0 Li 2 O: 2.5-4.0 Na 2 O: 0-2.0 K 2 O: 0-2.0 MgO: 0-0.5 ZnO: 1.0-5.0 CaO: 0-4.0 BaO: 1.0-5.0 TiO 2 : 0-5.0 ZrO 2 : 0-3.0 As 2 O 3 : 0-1.5 or Sb 2 O 3 and having sufficient nucleating agents to form crystallites throughout the body and P 2 O 5 is present.

Claim 28

A glass-ceramic according to claim 22, wherein the P 2 O 5 is present in an amount of 1 to 8% by weight.