On the base of Zircon Powder amount (%) of 3,6, 9 and 12; and the Aluminum Powder amount (%) of 5, 10 and 15, the sample after 3h burning at 1600 ℃, then heating 1100 ℃ and air-cooled,and after 3 cycles the greater flexural strength value, the better the thermal shock resistance.

With the increase powder was added, the flexural strength retention rate gradually improve, indicating that thermal shock resistance is getting better. Because magnesium zirconium refractory castable is added with zircon powder at a high temperature to form a forsterite and ZrO2, ZrO2 has toughening effect and improved thermal shock resistance; In magnesium aluminum refractory castable, adding alumina powder, MA formed at high temperatures, because of the linear expansion coefficient differences between the MA and periclase, the two formed around the thermal stress generated when the micro-cracks and micro-contractile ring, which can prevent the spread of cracks and thermal shock absorbing material, thus improving the thermal shock resistance of the material.