Incidence of porosity on the thermal properties of a sample sieved and compacted at constant pressure

Abstract

The knowledge of the thermal properties of materials in granular form plays an important role both in industry and in materials science, due to their applications and risks that can bring people into different industrial production processes. In the ceramics industry very little work is done on the knowledge of thermal properties - thermal conductivity (K), thermal diffusivity (α), thermal effusivity () and specific heat per unit ε volume (C)- depending on porosity or grain size. The present work is located within the type of applied exploratory research, which aims to determine the thermophysical properties (k, α, ε, C) at room temperature, of samples of red clay powders manufactured by spray dried processes, depending on variables such as the distribution of particle size, porosity and compaction pressure. To determine the granulometric distribution was used the vibrotamiz mark Gabrielli®, which was left vibrating for a time of five minutes, in order to know the clay powder through in each mesh and retained in the next. The compaction process was carried out through a manual equipment, where the sample is applied a constant load or pressure of 200 kg / cm2 . The properties -thermal conductivity (K) and thermal diffusivity (α)- were measured through the sh-1 dual sensor belonging to the KD2 Pro device, the other two properties -thermal effusivity () and the specific heat per unit volume ε(C)- were calculated using the values of K and α, and the expressions y respectively. The thermal properties (k, α, ε and C) of the sieved sample, compacted at constant pressure of 200 kg/cm2 depending on the size of the grain or the relative porosity, decrease with increasing the grain size and its relative porosity; the reduction in the vacuum index is observed.