Strengthening Binders for Porous Permeable Ceramic with Electromelted Corundum Filler

Abstract

Strong porous permeable ceramic is studied, prepared by selection of grain size compositions with filler of electromelted corundum grades F600 (100 – 200 μm), F360 (40 – 60 μm), and F120 (10 – 20 μm). The strengthening binders used are very fine corundum powder (~2 μm), alloyed with 0.25 wt.% MgO; a mixture of SiC (particle size 3 – 4 μm) and MgO (particle size 1 – 2 μm) in a ratio of 2:1. Specimens in the form of bars 60 × 15 × 5.5 mm are prepared by uniaxial semidry compaction under a pressure of 50 MPa (for single fraction compositions) and 25 MPa (for three-fraction compositions). Specimens are fired in air at temperatures from 1350 to 1550°C. Specimen open porosity varies from 28 to 43%, and ultimate strength in bending from 1 to 36 MPa. The best strength is obtained using a binder in the system SiC–MgO (5 wt.% binder above 100% of filler, σ_ben = 36 MPa, and open porosity is 30%).