Zirconia-toughened glass ceramics
ZrO 2 -toughened glass ceramics having high molar fractions of tetragonal ZrO 2 and fracture toughness value of greater than 1.8 MPa·m 1/2 . The glass ceramic may also include also contain other secondary phases, including lithium silicates, that may be beneficial for toughening or for strengthening through an ion exchange process. Additional second phases may also decrease the coefficient of thermal expansion of the glass ceramic. A method of making such glass ceramics is also provided.
1 . A glass-ceramic, comprising:
a crystalline phase comprising:
crystals of tetragonal zirconia, and
crystals of lithium disilicate; and
a glass phase;
wherein the glass-ceramic comprises a fracture toughness of from 1.8 to 10 MPa.m 1/2 , as measured by Chevron notch short bar method; and
wherein the crystals of tetragonal zirconia and lithium disilicate comprise 60-95 wt % of the total glass-ceramic.
2 . The glass-ceramic of claim 1 , wherein the tetragonal zirconia comprises a weight percent (wt %) of the total zirconia in the glass-ceramic, measured as the (((weight of the tetragonal zirconia)/(total weight of zirconia in the glass-ceramic))*100), and wherein the tetragonal zirconia comprises 40-95 wt % of zirconia in the glass-ceramic.
3 . The glass-ceramic of claim 1 , wherein the lithium disilicate comprises a weight percent (wt %) of the total glass-ceramic, measured as the (((weight of the lithium disilicate)/(total weight the glass-ceramic))*100), and wherein the lithium disilicate comprises from 25-60 wt % of the total glass-ceramic.
4 . The glass-ceramic of claim 1 , wherein the crystalline phase further comprises crystals selected from the group consisting of lithium aluminosilicate, cristobalite, β-spodumene, lithiophosphate, lithium orthophosphate, β-quartz solid solution, baddeleyite, lithium metasilicate, monoclinic zirconia, cubic zirconia, zekzerite, (Na,Li)ZrSi 6 O 18 , and combinations thereof.
5 . The glass-ceramic of claim 1 , wherein the crystalline phase further comprises crystals of monoclinic zirconia and crystals selected from the group consisting of lithium aluminosilicate, β-spodumene solid solution, β-quartz solid solution, or α-quartz.
6 . The glass-ceramic of claim 1 , wherein the glass-ceramic comprises >0-14 mol % of a sum of alkali metal oxides Na 2 O, K 2 O, and Cs 2 O.
7 . The glass-ceramic of claim 1 , wherein the glass-ceramic comprises >0-10 mol % of a sum of alkaline earth metal oxides MgO, CaO, SrO, and BaO.
8 . The glass-ceramic of claim 1 , wherein the glass-ceramic comprises >0-5 mol % of a sum of oxides Sc 2 O 3 , Y 2 O 3 , La 2 O 3 , Ce 2 O 3 , Pr 2 O 3 , Nd 2 O 3 , Pm 2 O 3 , Sm 2 O 3 , Eu 2 O 3 , Gd 2 O 3 , Tb 2 O 3 , Dy 2 O 3 , Ho 2 O 3 , Er 2 O 3 , Tm 2 O 3 , Yb 2 O 3 , and Lu 2 O 3 .