Patent ID: 7687422

Claim:
A fused and cast refractory product with a high zirconia content comprising, as percentages by weight relative to the oxides and for a total of more than 98.5%: ZrO 2 + Hf 2 O: >85% SiO 2 : 1% to 10% Al 2 O 3 : 0.1% to 2.4% B 2 O 3 : >1.5%; and a dopant selected from the group consisting of CrO 3 , Nb 2 O 5 , MoO 3 , Ta 2 O 5 , WO 3 , and mixtures thereof, in a weighted quantity such that: 0.2%≦(8.84)CrO 3 +(1.66)Nb 2 O 5 +(6.14)MoO 3 +Ta 2 O 5 +(3.81)WO 3 .