Influencia del tamaño de grano en la conductividad térmica a altas temperaturas en polvos aislantes de MgO

We report measurements about the thermal conductivity (K) in magnesium oxide (MgO) powders in a range of temperatures (T) between 250 oC and 1000 oC for samples with three different grain sizes. In order to obtain these results we did an improvement in the steady state flow technique ASTM2858-90. This improvement consists in the automatic capture of temperature which allows to decrease the error. Our results show a lineal increasing of K as a function of T in each case, up to 200% when T pass from 259 oC to 1012 oC. At fixed temperature, K is different for each sample, up to 100%, the less is the grain size the more is the increasing of K and in the inverse case