B20 = 600 – 850 µm B30 = 425 – 600 µm B40 = 250 – 425 µm B60 = 125 – 250 µm B120 = 70 – 125 µm B170 = 45 – 90 µm B205 = 0 – 63 µm
ZrO2: 60–70 %,
SiO2: 28–33 %,
Al2O3: < 10 %
HV 1.0 ~ 700 = HRC 60–65