Sintered alumina-zirconia balls

A sintered bead exhibiting:

• the following crystalline composition, as percentages by weight based on the total weight of the crystalline phases and for a total of 100%:
• zircon<25%;
• 50%≤cubic zirconia+tetragonal zirconia≤95%, the cubic zirconia content being greater than 50%, the cubic zirconia content being the (cubic zirconia/(cubic zirconia+tetragonal zirconia) ratio by weight);
• 0≤monoclinic zirconia≤(10−0.2*tetragonal zirconia) %;
• 5%≤corundum≤50%;
• crystalline phases other than zircon, cubic zirconia, tetragonal zirconia, monoclinic zirconia and corundum<10%;
• the following chemical composition, as percentages by weight based on the oxides:
• 34%≤ZrO2+HfO2, ZrO2+HfO2 being the remainder to 100%;
• HfO2≤4.0%;
• 0.5%≤SiO2≤14.1%;
• 4.5%≤Al2O3≤49.6%;
• 2.75%≤Y2O3≤22.8%;
• MgO≤5%;
• CaO≤2%;
• oxides other than ZrO2, HfO2, SiO2, Al2O3, MgO, CaO and Y2O3<5.0%,
• “stabilized zirconia” meaning an assembly consisting of said tetragonal zirconia and said cubic zirconia.