Hydrothermal Corrosion of Magnesia-Pyrochlore Composites for Inert Matrix Materials

Abstract

The corrosion behavior of MgONd 2 Zr 2 O 7 cercer composites was investigated under hydrothermal conditions at 300 C and saturation pressure. It was found that corrosion resistance was microstructure dependent in terms of MgO contiguity and homogeneity. The inhomogeneous composites completely dissolved in less than 1 h showing poor hydration resistance similar to MgO. The homogeneous composites exhibited an improved hydration resistance and the corrosion was primarily limited to the surface. The normalized mass loss (NML) was proportional to the corrosion time and the NML rate increased with MgO volume fraction. The corrosion process followed an Arrhenius relationship and the apparent activation energy was calculated to be $3941 kJ/mol. It is suggested that the mass loss of the MgONd 2 Zr 2 O 7 composites is mainly governed by hydration of MgO and the NML rate is enhanced by contiguity of MgO. A desirable microstructure with enhanced corrosion resistance is viewed to have minimum contiguity of MgO, good homogeneity, and large MgO grain size (minimizing grain boundaries).

Experiment and Modelling of Triangular Holes Array by Non-traditional Machining Process

“…Grilles with special-shaped holes have been developed as lightweight and efficient structures, these have advantages in the improvement of shielding and radar absorbing properties. Consequently, these structures are considered perfect structures for intake and outlet design [14][15][16]. Some other surface texturing, like regular well-defined micro/nanopatterns on the surface, is greatly applied to medical, chemicals, telecommunication, data storage, optics, and microelectronics [17].…”