Quartz crystal chemical stability, free from strong acid corrosion, in general, does not dissolve in water, does not produce deliquescence, but the quartz crystal in hydrofluoric acid and water glass can be dissolved, therefore, in the process we often use hydrogen fluoride Acid (HF) as a quartz crystal corrosion agent, the chemical reaction is as follows:

    (1) Si02 + 6HF = SiF4 + 2H20 + 2HF = H2SiF6 + 2H20

    (2) Si02 + 4HF = SiF4 + 2H20 3SiF4 + 3H20 = H2Si02 + 2H2SiF6

    The dissolution characteristics described above are also anisotropic to quartz, and the dissolution rate in the direction of the optical axis is 100 times faster than in the direction perpendicular to the optical axis; the axial direction is slower and the negative end of the axis is slower than the positive etch rate.