Analysis of anti-spalling mechanism of anti-stripping high alumina bricks
2018-06-21
The use of high alumina bauxite as the main raw material, the introduction of a small amount of ZrO2 (because ZrO2 is monoclinic and tetragonal phase transformation, can improve the product's thermal shock stability), adding a certain amount of composite binder and additives, through the control of mud The particle size distribution of the materials, and the refractory products obtained by molding and high-temperature firing become anti-stripping high alumina bricks.
The anti-stripping mechanism is due to the fact that the microstructure characteristics of ZrO2 have been determined to have anti-stripping properties.
1 There are obvious micro-cracks around the ZrO2 aggregates. The aggregates have obvious clearance and peeling from the surrounding corundum and mullite.
2 The well-developed ZrO2 aggregates are columnar and form a layered distribution in space. There are small slits between ZrO2. The size of the ZrO2 is only 1 to 5 μm, forming a channel structure. This kind of structure is superimposed on one another, with twists and turns, which is conducive to stress transmission and dispersion.
3 Mullite is well developed and fibrous. It interlaces with ZrO2 and corundum to form a composite reinforced structure. Obviously, ZrSiO4 reacts with surrounding Al2O3 when decomposed at high temperature to form ZrO2 and mullite. The presence of ZrO2 crystals prevents the growth of fibrous mullite crystals and plate-shaped corundum and is wrapped by it. Therefore, it is present around ZrO2. Chaotic state.
4 The petrographic analysis showed that the structures of corundum and mullite were staggered and ZrO2 intercalated. Among them, there were micro-cracks in the surroundings, and there were radial micro-cracks in the larger ZrO2 crystal itself and around it.
The above-mentioned structure of the anti-stripping high-alumina brick will have energy dissipation when subjected to stress, and improve the effect of thermal stability and high-temperature strength.
