Microstructure of Ceramic Layer in Composite Pipe Made by SHS-Gravitational Process
SHS-gravitational process was developed to synthesize the ceramic lined steel pipe, especially for elbow, conical pipe, three-way and four-way pipe and pipe with a small diameter. In SHS-gravitational process, the molten ceramic, which separated out from the reaction products due to their density difference, solidified to form the ceramic lined layer in the steel pipe when contacted with the steel pipe wall. With an X-ray diffractometer and a scanning electron microscope, it can be found that the ceramic layer is composed of α-Al2O3 and FeAl2O4. A small amount of iron also remains in the ceramic layer. There is a thin equiaxed grain area of alumina near the steel pipe wall, and then alumina was grown in form of dentrite to the surface of ceramic layer. FeAl2O4 distributes among alumina dentrite. Although the ceramic layer was solidified from one end to another end of a pipe, the microstructure of ceramic layer was almost uniform throughout the whole length of the pipe.
Wei Pan and Jianghong Gong
T. Lin et al., "Microstructure of Ceramic Layer in Composite Pipe Made by SHS-Gravitational Process", Key Engineering Materials, Vols. 336-338, pp. 1722-1724, 2007