In situ investigation of ceramic sintering by synchrotron radiation X-ray computed tomography

In this study, microstructure evolution of ceramic materials during sintering is investigated by synchrotron radiation X-ray computed tomography technique. Two kinds of specimens, including loose ceramic powder and compacted bulk material, are studied. The reconstructed 2D and 3D structures are obtained by analyzing the projection images with filtered backprojection algorithm. Sintering phenomena during three sintering stages, including grain contact, grain growth, sintering neck growth, and pore spheroidization, are clearly observed in both the reconstructed images of ceramic powder and the compacted bulk samples. For powder samples in the second sintering stage, the mean grain radius shows linear relationship with sintering time in double logarithmic coordinates obtained from the reconstructed images. The grain growth exponent of 0.34 is extracted from linear fitting of the curve. For compacted bulk materials, the change in porosity is obtained as a function of logarithmic sintering time, showing different densification characteristics in three sintering stages, and linear relationship between porosity and logarithmic time in the middle stage of sintering. The experimental results are in accordance with traditional sintering theory.