Gradient tinted articles and methods of making the same

Abstract

A glass-ceramic, includes a silicate-containing glass comprising a first portion and a second portion. A plurality of crystalline precipitates comprising at least one of W and Mo. The crystalline precipitates are distributed within at least one of the first and second portions of the silicate-containing glass. The glass-ceramic comprises a difference in absorbance between the first and second portions of 0.04 optical density (OD)/mm or greater over a wavelength range of from 400 nm to 1500 nm.

What is claimed is: 
     
         1 . A method of forming a glass-ceramic article, comprising:
 forming a substrate having a substantially homogenous glass composition, wherein the substrate comprises a first portion and a second portion; and   variably crystallizing at least one of the first and second portions of the substrate to form a plurality of crystalline precipitates within the at least one of the first and second portions,   wherein the variably crystallizing of the at least one of the first and second portions results in at least one of: (a) a difference in absorbance between the first and second portions of 0.04 OD/mm to 49 OD/mm over a wavelength range of from 400 nm to 750 nm, and (b) a difference in absorbance between the first and second portions of 0.03 OD/mm to 0.69 OD/mm over a wavelength range of from 750 nm to 1500 nm.   
     
     
         2 . The method of  claim 1 , wherein the step of variably crystallizing further comprises thermally processing the first and second portions of the substrate at different temperatures. 
     
     
         3 . The method of  claim 1 , wherein the step of variably crystallizing further comprises thermally processing the first and second portions of the substrate at the same temperature and cooling the first and second portions at different cooling rates. 
     
     
         4 . The method of  claim 1 , wherein the step of variably crystallizing further comprises increasing the temperature of the first and second portions at different heating rates. 
     
     
         5 . A method of forming a glass-ceramic article, comprising:
 forming a substrate having a substantially homogenous glass composition, wherein the substrate comprises a first portion and a second portion; and   thermally processing the first and second portions of the substrate at one or more of (a) different temperatures, (b) different heating rates and (c) different times,   wherein the thermally processing step is conducted to generate a plurality of crystalline precipitates in at least one of the first and second portions of the substrate such that (i) a difference in absorbance exists between the first and second portions of 0.04 OD/mm to 49 OD/mm over a wavelength range of from 400 nm to 750 nm and (ii) a Contrast Ratio between the first portion and the second portion is from 1.4 to 165 over a wavelength range of from 400 nm to 700 nm.   
     
     
         6 . The method of  claim 5 , wherein the glass-ceramic article further comprises WO 3  from 0 mol % to 15 mol %. 
     
     
         7 . The method of  claim 6 , wherein the WO 3  is from 0 mol % to 7 mol %. 
     
     
         8 . The method of  claim 5 , wherein the glass-ceramic article further comprises MoO 3  from 0 mol % to 15 mol %. 
     
     
         9 . The method of  claim 8 , wherein the MoO 3  is from 0 mol % to 7 mol %. 
     
     
         10 . The method of  claim 5 , wherein the step of thermally processing the first and second portions of the substrate is conducted such that the first and second portions are subjected to a temperature greater than 400° C. for different times.