Texture coefficients for the simulation of cordierite thermal expansion: A comparison of different approaches

The dependence of the coefficient of thermal expansion (CTE) from the texture description in porous ceramics is presented, in the example of cordierite. The texture description usually adopted for industrial ceramics, the I-ratio, is compared with the more rigorous approach of neutron diffraction (ND) pole figures. It is shown that the use of the I-ratio represents a coarse approximation of the complete materials texture and it yields different values of the texture coefficients used to model the CTE from lattice expansion data (according to the integrity function). For extruded and fired samples, it is shown that if for the transverse direction all approximations are equivalent, for the axial CTE the usual I-ratio values bring contradictory simulation results. On the contrary, the use of ND pole figures and of the Popa–Bruno method allows predicting sensible CTE values, consistent with other physical properties, such as Young's modulus.