The Toughness of Brown Aluminum Oxide
The quality of brown corundum has differences of good or bad , when selecting brown corundum , we mainly depends on its toughness. The higher toughness, the better quality , in fact, brown corundum toughness has a direct relationship with materials used for producing of corundum , In general, the better the quality of raw materials to produce the higher quality brown fused alumina toughness is also particularly good, of course,corundum toughness also has a certain relationship with production equipment and the level of the technical staff.
The toughness of corundum mainly decided by the following three factors:
First, the aluminum content of raw materials, aluminum content of raw materials directly determines the aluminum content of finished products, the higher the toughness of aluminum content the better, which is important reason why brown corundum raw materials must be high-quality bauxite.
Second, the corundum carbon content, brown corundum carbon content and the role of aluminum content on the contrary, the higher the carbon content of the lower the toughness of brown fused, low carbon content of brown jade does not generally burst, and particularly high agglomeration .
Third, brown corundum later processing, the brown jade finished into the furnace re-forging, to prevent changes in the color of brown jade, brown corundum at this time will show a clear blue-black.
Some BFA manufacturers add about 0.25% MgO in brown fused alumina to control the color of the brown fused alumina after calcination. The brown fused alumina containing this magnesium oxide additive tends to have a deeper, more consistent calcined blue color. This is presumably because MgO suppresses the growth of TiO2 grains and keeps the size within the range that makes blue light scattering.
The toughness of brown fused alumina increases with the growth of TiO2 nuclei. The TiO2 particles homogeneously dispersed in the α-alumina grains toughen the particles. A second phase which is well-dispersed in a ceramic material is a well-known mechanism of toughening of the material. The point of greatest ductility enhancement is before the blue corundum emits blue. Blue is not only important for the commercialization of consumers of corundum, but it also shows that brown fused alumina has been sufficiently calcined to increase its toughness.