Recession Behaviour of Oxides under High Velocity Steam Jet | Chapter 7 | New Horizons of Science, Technology and Culture Vol. 6

 

This review summarises the results of a collaborative research project between the Advanced Manufacturing Research Institute (AIST) and Oak Ridge National Laboratory (ORNL) from 2002 to 2005, conducted as part of the “US-Japan High-Level Consultation on Climate Change Science and Technology Working Group.” The focus was on water vapour as a corrosion species. The oxide was exposed to the same temperature and high-velocity steam jet conditions as those in gas turbines, and its corrosion behaviour was evaluated. The investigation targeted oxides with good corrosion resistance in preliminary tests and low coefficients of thermal expansion. Specifically, rare earth silicates, eutectic materials, and zircon were examined. The polycrystalline rare earth silicate phase developed a porous surface due to selective corrosion of the intergranular glass phase. The crystalline phase is also partially decomposed, resulting in a silica-deficient phase. In the corrosion of rare earth silicate phases, the presence of grain boundary glass phases significantly affected the stability of the crystalline phase itself. The Lu2Si2O7/Al6Si2O13 eutectic material, prepared through solidification, lacked glass phases at the grain boundaries, which prevented the formation of porous structures due to corrosion. The Al6Si2O13 phase was fully corroded. Tests on the zircon phase showed that the silica component leached from the crystalline structure. Generally, when double oxides containing silica are exposed to gas turbine conditions, phase decomposition occurs, leading to corrosion of the silica components. This results in the formation of a silica-deficient phase at the bulk surface. For many oxides, exposure tests conducted under gas turbine conditions have demonstrated that Lu2Si2O7 exhibits the highest corrosion resistance. Therefore, controlling the microstructure of the EBC layer containing this phase or the overall structure of the coating is significant for further enhancing corrosion resistance.

 

 

Author(s) Details

Shunkichi Ueno
College of Engineering, Nihon University, Koriyama, Fukushima 963-8642, Japan.

 

Hua Tay Lin
School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou 510006, China.

 

Please see the book here :- https://doi.org/10.9734/bpi/nhstc/v6/6762