Glass ceramic substrate made of a transparent, colored LAS glass ceramic and method for producing it
A glass ceramic substrate made of a transparent, colored LAS glass ceramic is provided. The glass ceramic has a gradient layer with keatite solid solution and an underlying core with high-quartz solid solution as predominant crystal phase. The keatite solid solution in a depth of 10 μm or greater exceeds 50% of the sum of the high-quartz solid solution proportion and keatite solid solution proportion. The ceramization includes a crystal transformation step, in which the high-quartz solid solution is transformed at a maximum temperature in the range of 910° to 980° and a time period of between 1 and 25 minutes in part into the keatite solid solution.
1. A glass ceramic substrate made of a transparent, colored LAS glass ceramic comprising a composition (in wt %):
Al 2 O 3 18-23,
Li 2 O 3.0-4.2,
SiO 2 60-69,
ZnO 0-2,
Na 2 O+K 2 O 0.2-1.5,
MgO 0-1.5,
CaO+SrO+BaO 0-4,
B 2 O 3 0-2,
TiO 2 2.3-4,
ZrO 2 0.5-2,
P 2 O 5 0-3,
SnO 2 0-<0.6,
Sb 2 O 3 0-1.5,
As 2 O 3 0-1.5,
TiO 2 +ZrO 2 +SnO 2 3.8-6,
V 2 O 5 0.01-0.06, and
Fe 2 O 3 0.03-0.2,
wherein the LAS glass ceramic has a gradient layer and an underlying core, and
wherein the LAS glass ceramic has keatite solid solution (KSS) as a predominant crystal phase in the underlying core and has high-quartz solid solution (HQSS) as a predominant crystal phase in the gradient layer,
further comprising a depth profile of the HQSS and KSS crystal phase proportions, wherein the KSS crystal phase has a proportion in any depth ≥20 μm that exceeds 50% of a sum of the HQSS and KSS crystal phase proportions.
2. The glass ceramic substrate according to claim 1 , further comprising coloring oxides in sum total to a maximum of 1.0 wt %.
3. The glass ceramic substrate according to claim 1 , wherein the LAS glass ceramic has a fracture strength, expressed in a CIL value, of at least 0.8 N in the case of an ambient humidity of 10% and/or a CIL value of at least 0.98 N in the case of an ambient humidity of 1%.
4. The glass ceramic substrate according to claim 1 , wherein the depth profile of the HQSS and KSS crystal phase proportions is achieved by phase transformation of HQSS crystals to KSS crystals during ceramization with a maximum temperature T max and over a residence time t(T max ) of this maximum temperature in a temperature-time region that is delimited by four straight lines, which connect the four corner points with the value pairs (T max =910° C.; t(T max )=25 minutes), (T max =960° C.; t(T max )=1 minute), (T max =980° C.; t(T max )=1 minute), and (T max =965° C.; t(T max )=25 minutes),
wherein the ceramization method, including the time period for cooling to a temperature of 780° C., requires overall less than 60 min.
5. A glass ceramic substrate made of a transparent, colored LAS glass ceramic comprising a composition (in wt %):
Al 2 O 3
18-23,
Li 2 O
3.0-4.2,
SiO 2
60-69,
ZnO
0-2,
Na 2 O + K 2 O
0.2-1.5,
MgO
0-1.5,
CaO + SrO + BaO
0-4,
B 2 O 3
0-2,
TiO 2
2.3-4,
ZrO 2
0.5-2,
P 2 O 5
0-3,
SnO 2
0-<0.6,
Sb 2 O 3
0-1.5,
As 2 O 3
0-1.5,
TiO 2 + ZrO 2 + SnO 2
3.8-6,
V 2 O 5
0.01-0.06, and
Fe 2 O 3
0.03-0.2,
wherein the LAS glass ceramic has a gradient layer and an underlying core,
wherein the LAS glass ceramic has keatite solid solution (KSS) as a predominant crystal phase in the underlying core and has high-quartz solid solution (HQSS) as a predominant crystal phase in the gradient layer, and
wherein the LAS glass ceramic has a fracture strength, expressed in a CIL value, of at least 0.8 N at an ambient humidity of 10% and/or a CIL value of at least 0.98 N at an ambient humidity of 1%.
6. The glass ceramic substrate according to claim 5 , further comprising coloring oxides in sum total to a maximum of 1.0 wt %.
7. The glass ceramic substrate according to claim 5 , wherein the fracture strength is achieved by phase transformation of HQSS crystals to KSS crystals during ceramization with a maximum temperature T max and over a residence time t(T max ) of this maximum temperature in a temperature-time region that is delimited by four straight lines, which connect the four corner points with the value pairs (T max =910° C.; t(T max )=25 minutes), (T max =960° C.; t(T max )=1 minute), (T max =980° C.; t(T max )=1 minute), and (T max =965° C.; t(T max )=25 minutes)
wherein the ceramization method, including the time period for cooling to a temperature of 780° C., requires overall less than 60 in.
8. The glass ceramic substrate according to claim 5 , wherein the LAS glass ceramic has a maximum scattered proportion, standardized to a glass ceramic with a thickness of 4 mm, is at most 15% at a wavelength of 470 nm.
9. The glass ceramic substrate according to claim 8 , wherein the maximum scattered proportion does not exceed 20% in a wavelength range from 400 nm to 500 nm.
10. The glass ceramic substrate according to claim 5 , wherein the LAS glass ceramic
is free of arsenic and antimony, apart from unavoidable traces, and contains at least 0.1 wt % SnO 2 .
11. The glass ceramic substrate according to claim 5 , wherein the composition meets a condition 1<Fe 2 O 3 /V 2 O 5 <8.
12. The glass ceramic substrate according to claim 6 , wherein the coloring oxides comprise at least one substance selected from the group consisting of Cr, Mn, Co, Ni, Cu, Se, Mo, W, oxides thereof, and metal oxides of rare earths.
13. The glass ceramic substrate according to claim 5 , wherein the LAS glass ceramic has an integral visual transmission in the visible range, standardized to a glass ceramic with a thickness of 4 mm, of τ vis, 4 mm <=5%.
14. The glass ceramic substrate according to claim 5 , wherein the LAS glass ceramic has a spectral transmission, standardized to a glass ceramic with a thickness of 4 mm, of >0.1% at a wavelength of 470 nm and/or of >0.25% at a wavelength of 550 nm.
15. The glass ceramic substrate according to claim 5 , further comprising a glassy surface zone on the gradient layer, the glassy surface zone has a thickness of 300-1000 nm.
16. The glass ceramic substrate according to claim 5 , wherein the underlying core has a crystal proportion that is at most 82%.
17. The glass ceramic substrate according to claim 5 , wherein the substrate is configured for a use selected from the group consisting of a covering for a heating element, whiteware, a grill top, a fireplace panel, a support plate, an oven lining, chemically resistant laboratory fixtures, a high-temperature article, an extremely low-temperature article, a furnace window for combustion furnaces, a heat shield for shielding of hot surroundings, a cover for reflectors, floodlights, projectors, beamers, photocopiers, an article exposed to thermomechanical loads, night vision device, wafer substrate, translucent articles with UV protection, material for housing components, electronic devices, glass cover screens for IT, cell phone, laptop, scanner glass plate, facade plate, fire-resistant glazing, and ballistic protection.
18. A glass ceramic substrate made of a transparent, colored LAS glass ceramic comprising a composition (in wt %):
Al 2 O 3
18-23,
Li 2 O
3.0-4.2,
SiO 2
60-69,
ZnO
0-2,
Na 2 O + K 2 O
0.2-1.5,
MgO
0-1.5,
CaO + SrO + BaO
0-4,
B 2 O 3
0-2,
TiO 2
2.5-4,
ZrO 2
0.5-2,
P 2 O 5
0-3,
SnO 2
0-<0.6,
Sb 2 O 3
0-1.5,
As 2 O 3
0-1.5,
TiO 2 + ZrO 2 + SnO 2
3.8-6,
V 2 O 5
0.01-0.06, and
Fe 2 O 3
0.03-0.2,
wherein the LAS glass ceramic has a gradient layer and an underlying core, and
wherein the LAS glass ceramic has keatite solid solution (KSS) as a predominant crystal phase in the underlying core and has high-quartz solid solution (HQSS) as a predominant crystal phase in the gradient layer,
further comprising a depth profile of the HQSS and KSS crystal phase proportions, wherein the KSS crystal phase has a proportion in any depth ≥20 μm that exceeds 50% of a sum of the HQSS and KSS crystal phase proportions,
wherein the depth profile of the HQSS and KSS crystal phase proportions is achieved by phase transformation of HQSS crystals to KSS crystals during ceramization with a maximum temperature T max and over a residence time t(T max ) of this maximum temperature in a temperature-time region that is delimited by four straight lines, which connect the four corner points with the value pairs (T max =910° C.; t(T max )=25 minutes), (T max =960° C.; t(T max )=1 minute), (T max =980° C.; t(T max )=1 minute), and (T max =965° C.; t(T max )=25 minutes), and
wherein the ceramization method, including the time period for cooling to a temperature of 780° C., requires overall less than 60 min.
19. A glass ceramic substrate made of a transparent, colored LAS glass ceramic comprising a composition (in wt %):
Al 2 O 3
18-23,
Li 2 O
3.0-4.2,
SiO 2
60-69,
ZnO
0-2,
Na 2 O + K 2 O
0.2-1.5,
MgO
0-1.5,
CaO + SrO + BaO
0-4,
B 2 O 3
0-2,
TiO 2
2.3-4,
ZrO 2
0.5-2,
P 2 O 5
0-3,
SnO 2
0-<0.6,
Sb 2 O 3
0-1.5,
As 2 O 3
0-1.5,
TiO 2 + ZrO 2 + SnO 2
3.8-6,
V 2 O 5
0.01-0.06, and
Fe 2 O 3
0.03-0.2; and
wherein the LAS glass ceramic has a gradient layer and an underlying core,
wherein the LAS glass ceramic has keatite solid solution (KSS) as a predominant crystal phase in the underlying core and has high-quartz solid solution (HQSS) as a predominant crystal phase in the gradient layer,
wherein the LAS glass ceramic has a fracture strength, expressed in a CIL value, of at least 0.8 N at an ambient humidity of 10% and/or a CIL value of at least 0.98 N at an ambient humidity of 1%,
wherein the fracture strength is achieved by phase transformation of HQSS crystals to KSS crystals during ceramization with a maximum temperature T max and over a residence time t(T max ) of this maximum temperature in a temperature-time region that is delimited by four straight lines, which connect the four corner points with the value pairs (T max =910° C.; t(T max )=25 minutes), (T max =960° C.; t(T max )=1 minute), (T max =980° C.; t(T max )=1 minute), and (T max =965° C.; t(T max )=25 minutes), and
wherein the ceramization method, including the time period for cooling to a temperature of 780° C., requires overall less than 60 min.