Detailed studies on microstructural evolution during the high temperature corrosion of SiC-containing andalusite refractories in the cement kiln preheater

Abstract The corrosion chemistry of SiC-modified andalusite refractories has been studied using a post-mortem approach that considers both K + and Ca 2+ ions as the main corrosive agents existing in the cyclone preheater applied in the cement production line. The transient progress of corrosion reactions was investigated as the function of distance from the face exposed to the corrosive media (hot face) to the relatively little altered middle zone of Al 2 SiO 5 -SiC brick. Chemical alteration of the Al 2 SiO 5 and SiC grains was examined and discussed on the basis of phase equilibria in binary (CaO-SiO 2 , K 2 O-SiO 2 ) and ternary (K 2 O-Al 2 O 3 -SiO 2 , CaO-Al 2 O 3 -SiO 2 ) systems. Ca and K-Si-oxide phases along with Ca-aluminosilicate – gehlenite Ca 2 Al 2 SiO 7 and K-aluminosilicates – kalsilite KAlSiO 4 and leucite KAlSi 2 O 6 were formed as a consequence of the reactions between both SiO 2 and Al 2 SiO 5 with CaO and K 2 O. The heating microscopy thermal analysis was used to evaluate the behavior of SiC-/ZrSiO 4 -andalusite refractory bricks in contact with a partly decarbonized material.