Hydration properties of vermiculite in phenolic resin friction composites

The dehydration and rehydration properties of the Mg-vermiculite are strongly affected by their crystal structure. Changes in the structure of Mg-vermiculite after dehydration and rehydration were used for evaluation of dehydration properties of composite materials containing vermiculite and phenol formaldehyde resin during friction process and for estimation of temperature on the surface of composite. From XRD patterns follows that d-spacing of the first basal diffraction varies as a function of applied annealing temperature and Mg-vermiculite alone rehydrates if the heating temperature does not exceed 700 °C. If embedded in a phenolic resin matrix, rehydration ability of vermiculite is limited and depends on vermiculite/resin content ratio. The maximum detected temperature on the friction surface of investigated composite samples after friction test was 900 °C.