Effect of porosity on thermal conductivity of Li2TiO3 ceramic compact

The thermal conductivity of the porous ceramic materials strongly depends on its temperature and porosity. Li2TiO3 ceramic is considered as a tritium breeder material for the Indian fusion blanket concept. Inside the blanket, higher lithium content is vital in terms of lithium burn up, whereas porosity is essential for the diffusion of tritium from its grains to the surface. As the helium gas will continuously pass through the ceramic breeder?s pores, all heat transfer modes, i.e. conduction, convection and radiation will appear within the breeder canister. For evaluation of the heat transfer behaviour inside the fusion blanket, it is substantial to determine the porosity dependent thermal conductivity of Li2TiO3 along with a good relationship. In this work, Li2TiO3 compacts of different porosity, i.e. 4?6 %, 11 %, 24 %, 26 % and 39 % are prepared by uni-axial hydraulic pressing. Compacts are sintered at 1073 K, 1173 K, 1273 K and 1423 K for desired porosity. Thermal diffusivity of Li2TiO3 compacts are measured by laser flash apparatus from room temperature to 973 K. Thermal conductivity of porous Li2TiO3 compacts is calculated by multiplication with respective density and specific heat to the measured thermal diffusivity. In this study, the mercury intrusion technique and Scanning Electron Microscopy technique was used for the density, porosity and surface morphology, respectively. The effect of the temperature and porosity on the thermal conductivity of Li2TiO3 are presented here. As the thermal conductivity changes with porosity by virtue of temperature, the correlations are presented by fitting various models such as Maxwell model, modified Maxwell-Eucken model, Loeb model, modified Loeb model, and EMT model. Among these models, the best-fitted model was evaluated. The geometrical factor (?, ?) and thermal conductivity at 0 % porosity (k0) for the modified Maxwell-Eucken model and modified Loeb model were calculated. The porosity and temperature-dependent thermal conductivities of Li2TiO3 were calculated with newly obtained coefficients and discussed in this paper.