Polycrystalline porous Al
The present invention relates to temperature-treated polycrystalline porous Al 2 O 3 bodies comprising an amount of α aluminum oxide of more than 97% by weight, an amount of other oxide alloying components of a total of less than 3% by weight, a macroporosity of between 5 and 30% by volume, wherein the Al 2 O 3 bodies are composed of a plurality of Al 2 O 3 primary crystals comprising a crystallite size of between 20 and 100 μm.
1. Polycrystalline porous Al 2 O 3 bodies of molten aluminum oxide comprising
an amount of a aluminum oxide of more than 97% by weight: and
an amount of other oxide alloying components of a total of less than 3% by weight, wherein
the Al 2 O 3 bodies comprise a plurality of Al 2 O 3 primary crystals having a crystalline size of between 20 and 100 μm,
the Al 2 O 3 bodies exhibit a macroporosity comprising a pore volume of between 5and 30% by volume, an average diameter of the pores of between 5 and 30% by volume, an average diameter of the pores of between 20 and 60 μm and a maximum pore diameter in the range of approx. 100 μm, and
at the boundaries of the primary crystals, the polycrystalline Al 2 O 3 bodies comprise concentrations of individual TiO 2 comprising extrinsic phases, the extrinsic phases have a diameter of less than 7 μm and are distributed individually either in a punctiform manner or in lines along the primary crystal boundaries.
2. The Al 2 O 3 bodies according to claim 1 ,
wherein the extrinsic phases have a diameter of less than 5 μm.
3. The Al 2 O 3 bodies according to claim 1 ,
wherein the extrinsic phases comprise beside TiO 2 other oxide alloying components selected from the group consisting of Cr 2 O 3 , Fe 2 O 3 , MgO, Na 2 O, NiO, ZnO, CoO, ZrO 2 , SiO 2 , MnO 2 , or oxides of rare earths.
4. The Al 2 O 3 bodies according to claim 1 , wherein the amount of other oxide alloying components is less than 1% by weight.
5. The Al 2 O 3 bodies according to claim 1 , wherein the Al 2 O 3 bodies are abrasive grains, which are treated and sized into defined grit sizes.
6. The Al 2 O 3 bodies according to claim 5 , wherein the abrasive grains have a bulk density of less than 175 g/cm 3 in the grit sizes F24-F80according to FEPA.
7. The Al 2 O 3 bodies according to claim 5 , wherein the abrasive grains have a bulk density of less than 1.70 g/cm3 in the grit sizes F24-F80 according to FEPA.
8. The Al 2 O 3 bodies according to claim 5 , wherein the abrasive grains have a bulk density of less than 1.65 g/cm3 in the grit sizes F24-F80according to FEPA.