Fig. 7. (a) SEM-EDS images of the reaction products after 2 h exposure of KCl to a mixed gas of SO2:0.9 vol%–O2:5 vol%–H2O:10 vol%–N2:balance at 723 and1023 K. (b) SEM-EDS images of the reaction products after 2 h exposure of CaCl2 to a mixed gas of SO2:0.9 vol%–O2:5 vol%–H2O:10 vol%–N2:balance at 723 and1023 K. (c) SEM-EDS images of the reaction products after 2 h exposure of NaCl to a mixed gas of SO2:0.9 vol%–O2:5 vol%–H2O:10 vol%–N2:balance at 723 and1023 K.