China Professional Fused Rebonded Magnesite Chrome Brick manufacturers and suppliers
Since direct bonded magnesia chromium bricks and rebonded (semi-rebonded) magnesia chrome bricks have the characteristics of low impurity content and high temperature (ultra-high temperature) firing, such products are also called high-temperature fired magnesia chromium bricks.
The use of synthetic magnesia-chromium sand is the technological basis for producing rebonded and semi-rebonded magnesia-chrome bricks. Direct bonding and secondary spinelization are the theoretical basis of the production process of magnesia-chromium refractory materials.
The so-called secondary spinel is spinel formed by high temperature treatment or chemical reaction and has a different composition from the original chromium ore. There are three main types:
(1) Spinel-liquid phase crystallization.
The silicate phase in magnesia chrome bricks mainly comes from gangue in chromium ore.
The distribution of gangue in chromium ore is uneven. Therefore, the liquid phase formed after melting is also difficult to distribute uniformly and will be locally enriched. After the chromium ore surface is dissolved in the liquid phase, most of the re-precipitated euhedral secondary spinels are euhedral.
(2) Transitional composition spinel.
Transitional composition spinel refers to the reaction zone formed between chromium ore or spinel and periclase. It is a transition zone with a gradual composition. Such a reaction layer zone contributes the most to direct bonding, and some parts achieve "welding" between phases. ”, some exhibit microcracks.
(3) Solvent spinel.
The desolvated phase in the periclase crystal is the third form of spinel. It has no effect on the direct bonding between phases, but it plays an important role in changing the properties of the periclase solid solution, which can improve the erosion resistance of acidic media; improve the resistance to corrosion. Thermal shock resistance and toughness.
