Elaboration et caractérisation microstructurale et mécanique des réfractaires à base de kaolin DD3 et de dolomite (5-20%poids)

Abstract

The east Algerian kaolin DD3 is characterized by its wealth of alumina and its physical and mechanical properties after calcination. The aim of this work is to improve these properties by addition of dolomite to calcined kaolin DD3 (Grog) and to reduce the rate of vitreous phase. The latter is presented in the form of cristobalite between 1100°C and 1400°C and an amorphous phase above 1400°C. An excess of the amorphous phase reduce the creep strength and decrease the thermomechanical properties of the refractory. The mixtures between 5 and 20% weight of dolomite were treated and sintered under the same conditions between 1200°C and 1550°C. The samples are analyzed by XRI), SEM and physical and mechanical measurements. XRD Spectra show that the addition from 5 to 20% weight of dolomite led, after sintering, to form ceramic composite composed mainly of phases: mullite, anorthite, spinel and indialite (cx-cordierite). 1 he addition of dolomite more than 10% reduces the rate of the amorphous phase to 9.6% after sintering in the temperature range 1200°C and 1500°C. Ceramics obtained is characterized by: an apparent density in the range 2,88 to 3,21 g/cm3, a very low porosity, a module of rupture between 67 and 112 MPa and a Vickers microhardness from 9,1 to 10,67 GPa. © Lavoisier, Paris Refractaires a base de kaolin DD3.