Effect of Sintering and Cordierite Additives on the Physical and Mechanical Properties of Mullite Based Ceramics Prepared From Iraqi Raw Materials

Abstract

Mullite and cordierite are produced in the laboratory from Iraqi raw materials, have been crushed individually to obtain dense ceramic bodies to a particle size smaller than 45µ. Five mixtures of cordierite and mullite have been prepared in which cordierite has been added to mullite with the percentages of 30, 40, 50, 60, and 70 %. One hundred and twenty disk samples have been prepared using the semi-dry pressing method, with the pressure of 1000kg/cm2. The samples were dried and fired at different temperatures of 1300, 1350, 1400, and 1450 oC, with a soaking time of 2h. Physical evaluation tests (volume shrinkage, water absorption, apparent porosity, and bulk density) in addition to mechanical evaluation tests (compressive strength) have been performed. Samples fired at 1400 oC showed the best rates for the evaluation tests in general, in which the apparent porosity and water absorption for the samples were very low while the rates of density and compressive strength were high. The characteristics of samples fired at 1450 oC were overall poor while samples containing 60 and 70 % cordierite were melted. The best samples in this investigation were proven to be the ones containing 30% cordierite and 70% mullite while samples made out of 40% cordierite and 60% mullite show good mechanical and physical characteristics. The best ideal sample was the one fired at 1400 oC and contained 30% cordierite and 70% mullite.