Fig. 6

Heating procedure: t1 – time of heating of furnace to T = X °C @ rate 300 °C/h; t2 = t1 + 60 min @ stable T = X °C; t3 – time of cooling of furnace to room temperature (non-linear); X = 300, 650, 1000 °C.

Heating procedure: t1 – time of heating of furnace to T = X °C @ rate 300 °C/h; t2 = t1 + 60 min @ stable T = X °C; t3 – time of cooling of furnace to room temperature (non-linear); X = 300, 650, 1000 °C.