Refractory object and process of forming a glass sheet using the refractory object
A refractory object can include at least approximately 10 wt % Al 2 O 3 and at least approximately 1 wt % SiO 2 . In an embodiment, the refractory object can include an additive. In a particular embodiment, the additive can include TiO 2 , Y 2 O 3 , SrO, BaO, CaO, Ta 2 O 5 , Fe 2 O 3 , ZnO, or MgO. The refractory object can include at least approximately 3 wt % of the additive. In an additional embodiment, the refractory object can include no greater than approximately 8 wt % of the additive. In a further embodiment, the creep rate of the refractory object can be at least approximately 1×10 −6 h −1 . In another embodiment, the creep rate of the refractory object can be no greater than approximately 5×10 −5 h −1 . In an illustrative embodiment, the refractory object can include a glass overflow trough or a forming block.
1. A refractory object comprising:
Al 2 O 3 at a content in a range of 10 wt % Al 2 O 3 to 94 wt % Al 2 O 3 ;
SiO 2 at a content of at least 1.1 wt % and no greater than 4 wt % SiO 2 ;
Y 2 O 3 at a content of at least 3 wt % and no greater than 8 wt % Y 2 O 3 .
2. The refractory object as recited in claim 1 , wherein the refractory object includes no greater than 1 wt % of an alkali metal oxide.
3. The refractory object as recited in claim 1 , wherein the refractory object comprises no greater than 0.3 wt % ZrO 2 .
4. The refractory object as recited in claim 1 , wherein the refractory object comprises at least 70 wt % Al 2 O 3 .
5. The refractory object as recited in claim 1 , wherein a fracture toughness of the refractory object is at least 2.1 MPa-m 1/2 .
6. The refractory object as recited in claim 1 , wherein the refractory object further comprises a silica phase.
7. The refractory object as recited in claim 6 , wherein a melting point of the silica phase is at least 1300° C.
8. The refractory object as recited in claim 7 , wherein the melting point of the silica phase is at least a sintering temperature used in forming the refractory object.
9. The refractory object as recited in claim 1 , wherein the refractory object includes a peripheral region disposed between an edge of the refractory object and the body portion and outside of the body portion.
10. The refractory object as recited in claim 1 , wherein the SiO 2 is provided as amorphous SiO 2 , crystalline SiO 2 , or a combination thereof.
11. The refractory object as recited in claim 1 , wherein the apparent porosity of the refractory object is no greater than 0.8 vol %.
12. The refractory object as recited in claim 1 , wherein the percentage of theoretical density of the refractory object is at least 91%.
13. The refractory object of recited claim 1 , wherein the creep rate of the refractory object is no greater than 5.0×10 −5 h −1 .
14. The refractory object as recited in claim 1 , comprising grains having an average size of at least 10 micrometers.
15. The refractory object as recited in claim 1 , comprising grains having an average size no greater than 500 micrometers.