Beta-quartz glass ceramics with controlled transmission and methods of making same

Abstract

Beta-quartz glass-ceramics containing in their composition neither arsenic oxide nor antimony oxide and having a controlled transmission curve, articles made using the glass-ceramics, including cooktops, and precursor glasses of such glass-ceramics.

1 .- 16 . (canceled) 
     
     
         17 . A glass-ceramic of the lithium aluminosilicate type, containing a beta-quartz solid solution as the predominant crystalline phase and having for a thickness of 4 mm:
 an integrated optical transmission, T v , in the visible range, between 0.8 and 2%,   an optical transmission at 625 nm of more than 3.5%,   an optical transmission at 950 nm from about 50% to about 70%, and   an optical transmission at 1,600 nm from about 65% to about 75%, wherein the optical transmissions are measured after a ceramming that comprises (in sequence): (a) heating to 650° C., (b) heating from 650° C. to 820° C. at a heating rate of 5° C./min, (c) heating from 820° C. to T max  at a heating rate of 15° C./min and holding, at T max  for about 7 to 10 minutes; and d) cooling from T max  at an oven cooling rate, wherein T max  is between about 920° C. and about 970° C.   wherein the composition of the glass-ceramic, expressed as percentages by weight of oxides, contains:   SnO 2  0.3-0.6   V 2 O 5  0.025-0.060   Cr 2 O 3  0.01-0.04   Fe 2 O 3  0.05-0.15   As 2 O 3 +Sb 2 O 3 <0.1, and   wherein the composition further comprises as base oxides expressed as percentages by weight of oxides:   SiO 2  60-72   Al 2 O 3  18-23   Li 2 O 2.5-4.5   MgO 0-3   ZnO 1-3   TiO 2  1.5-4   ZrO 2  0-2.5   BaO 0-5   CaO 0-2   Na 2 O 0-1.5   K 2 O 0-1.5, and   further wherein the composition contains less than 200 ppm of CoO.   
     
     
         18 . The glass-ceramic according to  claim 17 , the composition of which contains:
 SnO 2 >0.36-0.6   V 2 O 5  0.025-0.045.   
     
     
         19 . The glass-ceramic according to  claim 18 , the composition of which contains:
 As 2 O 3 +Sb 2 O 3 <0.05.   
     
     
         20 . The glass-ceramic according to  claim 17 , the composition of which contains:
 SnO 2  0.34-0.39   V 2 O 5  0.028-0.041   Cr 2 O 3  0.013-0.016.   
     
     
         21 . The article glass-ceramic according to  claim 17 , the composition of which is free of F and of Br, except for inevitable traces. 
     
     
         22 . The glass-ceramic according to  claim 17 , wherein the integrated optical transmission, T v , in the visible range, ranges from about 1% to about 1.7%. 
     
     
         23 . A glass-ceramic of the lithium aluminosilicate type, containing a beta-quartz solid solution as the predominant crystalline phase and having for a thickness of 4 mm:
 an integrated optical transmission, T v , in the visible range, between 0.8 and 2%,   an optical transmission at 625 nm of more than 3.5%,   an optical transmission at 950 nm from about 50% to about 70%, and   an optical transmission at 1,600 nm from about 65 to about 75%, wherein the optical transmissions are measured after a ceramming treatment,   wherein the composition of the glass-ceramic, expressed as percentages by weight of oxides, contains:   SnO 2  0.3-0.6   V 2 O 5  0.025-0.060   Cr 2 O 3  0.01-0.04   Fe 2 O 3  0.05-0.15   As 2 O 3 +Sb 2 O 3 <0.1, and   wherein the composition further comprises as base oxides expressed as percentages by weight of oxides:   SiO 2  60-72   Al 2 O 3  18-23   Li 2 O 2.5-4.5   MgO 0-3   ZnO 1-3   TiO 2  1.5-4   ZrO 2  0-2.5   BaO 0-5   SrO 0-5   with BaO+SrO 0-5   CaO 0-2   Na 2 O 0-1.5   K 2 O 0-1.5   P 2 O 5  0-5   B 2 O 3  0-2, and   further wherein the composition contains less than 200 ppm of CoO.   
     
     
         24 . The glass-ceramic according to  claim 23 , the composition of which contains:
 SnO 2 >0.36-0.6   V 2 O 5  0.025-0.045.   
     
     
         25 . The glass-ceramic according to  claim 24 , the composition of which contains:
 As 2 O 3 +Sb 2 O 3 <0.05.   
     
     
         26 . The glass-ceramic according to  claim 23 , the composition of which contains:
 SnO 2  0.34-0.39   V 2 O 5  0.028-0.041   Cr 2 O 3  0.013-0.016.   
     
     
         27 . The article glass-ceramic according to  claim 23 , the composition of which is free of F and of Br, except for inevitable traces. 
     
     
         28 . The glass-ceramic according to  claim 23 , wherein the integrated optical transmission, T v , in the visible range, ranges from about 1% to about 1.7%. 
     
     
         29 . The glass-ceramic according to  claim 23 , wherein the ceramming treatment comprises a maximum temperature held between about 920° C. and about 970° C. for about 7 to 10 minutes. 
     
     
         30 . A glass-ceramic of the lithium aluminosilicate type, containing a beta-quartz solid solution as the predominant crystalline phase and having for a thickness of 4 mm:
 an integrated optical transmission, T v , in the visible range, between 0.8 and 2%,   an optical transmission at 625 nm of more than 3.5%,   an optical transmission at 950 nm from about 50% to about 70%, and   an optical transmission at 1,600 nm from about 65% to about 75%, wherein the optical transmissions are measured after a ceramming treatment,   wherein the composition of the glass-ceramic, expressed as percentages by weight of oxides, contains:   SnO 2  0.3-0.6   V 2 O 5  0.025-0.060   Cr 2 O 3  0.01-0.04   Fe 2 O 3  0.05-0.15   As 2 O 3 +Sb 2 O 3 <0.1, and   wherein the composition further comprises as base oxides expressed as percentages by weight of oxides:   SiO 2  60-72   Al 2 O 3  18-23   Li 2 O 2.5-4.5   MgO 0-3   ZnO 1-3   TiO 2  1.5-4   ZrO 2  0-2.5   BaO 0-5   CaO 0-2   Na 2 O 0-1.5   K 2 O 0-1.5, and   further wherein the composition contains less than 200 ppm of CoO.   
     
     
         31 . The glass-ceramic according to  claim 30 , the composition of which contains:
 SnO 2 >0.36-0.6   V 2 O 5  0.025-0.045.   
     
     
         32 . The glass ceramic according to  claim 31 , the composition of which contains:
 As 2 O 3 +Sb 2 O 3 <0.05.   
     
     
         33 . The glass-ceramic according to  claim 30 , the composition of which contains:
 SnO 2  0.34-0.39   V 2 O 5  0.028-0.041   Cr 2 O 3  0.013-0.016.   
     
     
         34 . The glass-ceramic according to  claim 30 , the composition of which is free of F and of Br, except for inevitable traces. 
     
     
         35 . The glass-ceramic according to  claim 30 , wherein the integrated optical transmission, T v , in the visible range, ranges from about 1% to about 1.7%. 
     
     
         36 . The glass-ceramic according to  claim 30 , wherein the optical transmission at 62.5 nm is greater than 4%. 
     
     
         37 . The glass-ceramic according to  claim 30 , wherein an optical transmission at 450 nm is less than 0.1%. 
     
     
         38 . The glass-ceramic according to  claim 30 , wherein the ceramming treatment comprises a maximum temperature held between about 920° C. and about 970° C. for about 7 to 10 minutes.