The silica-base core for directionally solidified air-cooled blade and vane is composed of 30% zirconia and 70% quartz. Not only its refractoriness and strength are high as well as its chemistry stability and size precision are excellent, but also it can be removed easily. The high temperature deformation, bending strength, contraction and corroision rate of the core specimens were measured in the temperature range of 1200-1600 ℃, that were studied in detail by means of x-ray diffraction, scanning electron microscope, electron microprobe analysis and metallographic analysis. The results show that with the rise of temperature the contraction rate increases but the corrosion rate decreases mainly due to the variation of the viscous flow of core. The gap between the particles of core decreases, that makes the contraction rate increase. Because of the drop of microporosity, the contact area between core and corrosive liquid decreases. Therefore, corrosion rate becomes slower gradually. The dramatic increases of high temperature deformation around 1550 ℃ is mainly resulted from the formation of liquid phase (compound of Al_2O_3 and SiO_2). The remarkable impairment of bending strength between 1350-1400 ℃ is mainly due to a great deal of quartz transferring into crystalline state. Besides, the change of properties of core was studied in the condition of prolonged soaking at high temperature.
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