A simple method for the preparation of cordierite ceramics with high strength and low thermal expansion coefficient

Cordierite ceramics have great application prospects due to their very low coefficient of thermal expansion. However, the low purity of ceramics leads to their unsatisfactory fracture strength, which has always been a research focus. Herein, by applying external pressure to the green body of mixed raw materials and optimizing the synthesis temperature, high-purity cordierite powder was prepared, and then it was used as the starting material for the fabrication of high-strength cordierite ceramics. The optimal sample exhibited a flexural strength of 146 MPa, which is about 1.4 times that of the cordierite ceramics reported in the literature. This is attributed to applied external pressure increasing the contact area of raw materials, leading to a more thorough reaction, and the content of the alpha-cordierite phase is 98.4 wt% in the sample synthesized at 1275 degrees C. Concurrently, the samples possessed a thermal expansion coefficient of only 1.9 x 10-6 degrees C-1 (room temperature to 800 degrees C). In addition, the increase in columnar crystal volume fraction is also one of the reasons for the high strength and low thermal expansion coefficient of cordierite ceramics.