LAUSR

The kinetics of spinel (Al–Si) crystallization from Algerian halloysite (DD1) was investigated using differential thermal analysis. Experiments were carried out on samples between room temperature and 1400 ◦C with constant heating rate from 2 to 20 ◦C min−1. The activation energies measured from isothermal and non-isothermal treatments were 1054.85 and 1140 kJ mol−1, respectively, for the spinel (Al–Si) formation. The Avrami constant n obtained by the Ligero method and the m parameter obtained by the Matusita method were about 2 for spinel crystallization. This value indicates that the crystallization mechanism of Al–Si spinel phase proceeds by bulk nucleation of the phase formation with a constant number of nuclei and that the three-dimensional growth of crystals is controlled by diffusion.