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Stable and uniform crystal structure is the premise of good mechanical properties of glass ceramics, so strict control of hot die casting parameters is an important means to ensure the performance of glass ceramic products:

1. Die-casting temperature is too low --- incomplete die-casting: glass-ceramics are not softened enough and the viscosity is too high, which can easily cause incomplete glass-ceramic die-casting;

2. The die-casting temperature is too high --- the bending strength decreases: ① The viscosity of the glass ceramic is significantly reduced, and the fluidity is enhanced. The non-pressure injection can introduce bubbles into the material, causing the mechanical properties to decrease; ②Hot die-casting temperature much higher than the crystallization temperature may be accompanied by crystal growth or crystal transformation. After the crystal is abnormally increased, the difference in thermal expansion coefficient between the crystal and the matrix glass will cause the internal stress to increase, and even the result of micro cracks in the material.

——Effect of dental hot-press casting technology on microstructure and properties of new dental glass ceramics[J]. Functional materials, 2010, 5(41): 767-770