Magnesite is a free M g O crystal. Magnesium-zirconium brick M g O has little chemical affinity with S I O 2 and FeO 3. Magnesium brick manufacturers generally do not take part in chemical reactions during clinker calcination. It exists in clinker in the following forms:
It dissolves in C3A and C3S to form solid solution.
(2) Soluble in vitreous body.
(3) It exists in the form of free periclase. Researchers believe that the content of M g O in the first two forms is about 2% of clinker, and they have no destructive effect on hardened cement paste. However, in the form of periclase, because of its slow hydration rate, hydration will begin after half a year to one year, and the volume expansion of magnesium hydroxide will be 148%, which will lead to poor stability. The severity of expansion of periclase is related to the size and content of crystal. The bigger the size and the higher the content, the greater the harm. In production, quick cooling measures should be taken to reduce the crystal size of periclase.
Use of periclase
Periclase can be used as high quality raw materials for refractories (such as magnesia-alumina bricks, periclase-spinel bricks), glass-ceramics, thermocouples, high-temperature cables and insulation materials of electrical resistors.