The corrosion behavior of MgO-Nd2Zr2O7 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 ∼39-41 kJ/mol. It is suggested that the mass loss of the MgO-Nd2Zr2O 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).
Degueldre, C. and Paratte, J.M. (1999). Concepts for an Inert Matrix Fuel: An Overview, Journal of Nuclear Materials, 274(1-2): 1-6.
2.
Kleykamp, H. ( 1999). Selection of Materials as Diluents for Burning of Plutonium Fuels in Nuclear Reactors, Journal of Nuclear Materials, 275(1): 1-11.
3.
Neeft, E.A.C. , Bakker, K., Schram , R.P.C., Conrad, R. and Konings, R.J.M. (2003). The Efttra-T3 Irradiation Experiment on Inert Matrix Fuels, Journal of Nuclear Materials , 320(1-2): 106-116.
4.
Chauvin, N. , Albiol, T., Mazoyer, R., Noirot, J., Lespiaux, D., Dumas, J.C., Weinberg, C., Menard, J.C. and Ottaviani , J.P. ( 1999). In-pile Studies of Inert Matrices with Emphasis on Magnesia and Magnesium Aluminate Spinel, Journal of Nuclear Materials , 274(1-2): 91-97.
5.
Medvedev, P.G. , Frank, S.M., O’Holleran , T.P. and Meyer, M.K. ( 2005). Dual Phase MgO-ZrO2 Ceramics for Use in LWR Inert Matrix Fuel, Journal of Nuclear Materials, 342(1-3): 48-62.
6.
David, R. and Clarke, S.R.P. ( 2005). Thermal Barrier Coating Materials, Materials Today, 8: 22-29.
7.
Yates, S.J., Xu, P., Wang, J., Tulenko, J.S. and Nino, J.C. ( 2007). Processing of Magnesia-Pyrochlore Composites for Inert Matrix Materials, Journal of Nuclear Materials, 362(2-3): 336-342.
8.
Xu, P., Holliday, K., Czerwinski, K.R. and Nino, J.C. ( 2009). Dissolution Behavior of MgO-Pyrochlore Composites in Acidic Solutions, Journal of Nuclear Materials, 394(1): 39-45.
9.
Yates, S.J., McClellan, K.J. and Nino, J.C. ( 2009). The Effect of Processing on the Thermal Diffusivity of MgO-Nd2Zr2O7 Composites for Inert Matrix Materials, Journal of Nuclear Materials, 393(2): 203-211.
10.
Lutique, S. , Konings, R.J.M., Rondinella , W., Somers, J. and Wiss, T. (2003). The Thermal Conductivity of Nd2Zr2O7 Pyrochlore and the Thermal Behaviour of Pyrochlore-based Inert Matrix Fuel, Journal of Alloys and Compounds, 352(1-2): 1-5.
11.
Lutique, S. , Staicu, D., Konings , R.J.M., Rondinella , V.V., Somers, J. and Wiss, T. ( 2003). Zirconate Pyrochlore as a Transmutation Target: Thermal Behaviour and Radiation Resistance against Fission Fragment Impact, Journal of Nuclear Materials, 319: 59-64.
12.
Sickafus, K.E. , Minervini, L., Grimes , R.W., Valdez, J.A., Ishimaru, M., Li , F., McClellan, K.J. and Hartmann, T. ( 2000). Radiation Tolerance of Complex Oxides, Science, 289(5480): 748-751.
13.
Dehoff, R.T. (1965). Estimation of Particle-size Distributions from Simple Counting Measurements Made on Random Plane Sections , Transactions of the Metallurgical Society of AIME, 233(1): 25-29.
Wurst, J.C. and Nelson, J.A. (1972). Linear Intercept Technique for Measuring Grain-size in 2-Phase Polycrystalline Ceramics , Journal of the American Ceramic Society, 55(2): 109-111.
17.
Heijman, M.J.G.W. , Benes, N.E., ten Elshof, J.E. and Verweij, H. ( 2002). Quantitative Analysis of the Microstructural Homogeneity of Zirconia-toughened Alumina Composites , Materials Research Bulletin, 37(1): 141-149.
18.
Hendriks, M.G.H.M. , Heijman, M.J.G.W., van Zyl, W.E., ten Elshof, J.E. and Verweij, H. ( 2002). Quantitative Analysis of Microstructural Homogeneity and Capacitance Correlations in Palladium/Yttria-Stabilized Zirconia Composites , Journal of the American Ceramic Society , 85(8): 2097-2101.
19.
Kitamura, A. , Onizuka, K. and Tanaka, K. (1996). Hydration Characteristics of Magnesia, Taikabutsu Overseas , 16(3): 112-122.
20.
Scamehorn, C.A. , Harrison, N.M. and Mccarthy, M.I. (1994). Water Chemistry on Surface Defect Sites - Chemidissociation Versus Physisorption on MgO(001) , Journal of Chemical Physics, 101(2): 1547-1554.
21.
Herrmann, M. , Seipel, B., Schilm, J., Nickel, K.G., Michael, G. and Krell, A. ( 2005). Hydrothermal Corrosion of Zirconia-toughened Alumina (ZTA) at 200 Degrees C, Journal of the European Ceramic Society , 25(10): 1805-1812.
22.
Rocha, S.D.F. , Mansur, M.B. and Ciminelli , V.S.T. (2004 ). Kinetics and Mechanistic Analysis of Caustic Magnesia Hydration , Journal of Chemical Technology and Biotechnology, 79(8): 816-821.
23.
Blaha, J. ( 1995). Kinetics of Hydration of Magnesium-oxide in Aqueous Suspension .1. Method of Measurement and Evaluation of Experimental Data, Ceramics-Silikaty, 39(2): 45-51.
24.
Alexander, K.B. , Becher, P.F., Waters, S.B. and Bleier, A. (1994). Grain-growth Kinetics in Alumina-Zirconia (Cezta) Composites, Journal of the American Ceramic Society, 77(4): 939-946.
25.
Chen, I.W. and Xue, L.A. ( 1990). Development of Superplastic Structural Ceramics , Journal of the American Ceramic Society, 73(9): 2585-2609.
26.
French, J.D. , Harmer, M.P., Chan, H.M. and Miller, G.A. (1990). Coarsening-resistant Dual-phase Interpenetrating Microstructures, Journal of the American Ceramic Society, 73(8): 2508-2510.
27.
Lange, F.F. and Hirlinger, M.M. (1987). Grain-growth in 2-Phase Ceramics - Al2O3 Inclusions in ZrO2, Journal of the American Ceramic Society, 70(11): 827-830.
28.
Smithson, G.L. and Bakhshi, N.N. (1969). Kinetics and Mechanism of Hydration of Magnesium Oxide in a Batch Reactor, Canadian Journal of Chemical Engineering, 47(5): 508-513.
29.
Maryska, M. and Blaha, J. (1997). Hydration Kinetics of Magnesium Oxide - Part 3- Hydration Rate of MgO in Terms of Temperature and Time of Its Firing, Ceramics-Silikaty, 41(4): 121-123.
30.
Yates, S.J. ( 2009). Processing-thermal Conductivity Relationships in MgO-Pyrochlore Composite Inert Matrix Materials, PhD Thesis, University of Florida.
31.
Hashin, Z. ( 1962). The Elastic-moduli of Heterogeneous Materials , Journal of Applied Mechanics, 29: 143-150.
