Study On Cordierite Matrix Composites Reinforced By Al₂O₃Fibers

Cordierite composites have many excellent properties such as low thermal expansioncoefficient, high resistivity, good thermal shock resistance. They have been widely used inthe field of refractory materials, thermal shock resistance material and catalystcarrier materials, etc. However, the brittleness, is a big problem for its further application.In this thesis, the cordierite ceramics were prepared with steatite, Al₂O₃, SiO₂as rawmaterials.Al₂O₃f/cordierite ceramics were prepared using the alumina fiber （1%¹2%）, silica,alumina, and soapstone by the powder dispersion, mixing, pressing, sintering process; Theeffects of the content of various alumina fibers, preparation process and microstructure onlinear shrinkage, open porosity, bulk density, bending strength were studied, as well as thesintering mechanism of cordierite and the strengthening mechanism of Al₂O₃f/cordieriteceramics were studied.Test results indicate that with the increase in sintering temperature, the bulk density andbending strength of cordierite are gradually increased, especially over1325℃. When thetemperature reaches1400℃, the two indicators have reached the maximum（2.27g/cm3,4.75MPa）. Volume density and flexural strength of Al₂O₃f/cordierite composite at differentsintering temperature first are increased and then decreased with the increase in the content ofAl₂O₃fiber. The two indexes reaches the maximum when the content of Al₂O₃fiber is5%（When the temperature reached1400℃the two indexes reach2.65g/cm3and8.63MPa, increased by16.7%and81.6%compared with the matrix）. With the increase of thesintering temperature, these two indicators of the composite are improved as a whole.With the increase of the sintering temperature, the sintering neck is formed, the bulkdensity is increased, a new phase is formed by a reaction then a solid solution is formed withthe sintering process. Because Al₂O₃fiber and matrix have a good connection, the strength ofthe composites is improved depending on the energy consumption mechanisms such as fiberbridging, crack deflection, fiber breakage, fiber draw.In summary, the strengthening mechanisms of Al₂O₃f/cordierite composites have beenstudied in the present research. Based on the present research, a new approach to improve themicrostructure and mechanical properties of cordierite composites can be offered.