Effective Thermal and Electrical Conductivities of AgSnO2 During Sintering. Part I: Experimental Characterization and Mechanisms

Abstract

The effective thermal and electrical conductivities of porous materials have a major influence on the temperature field inside the sample during resistance sintering (RS). Thermal and electrical effective conductivities of AgSnO2 can be calculated during sintering by using numerical modeling with constitutive equations, which consider microstructural transformations. In Part I of this investigation, the emphasis is on the development of an understanding of the microstructure–conductivity relationship starting from the “green” state to the fully sintered state during RS of AgSnO2. This work focuses on the characterization of the electrical and thermal effective conductivities of the porous composite material (AgSnO2), and on highlighting the mechanisms, which drive the evolutions of the effective conductivities and the microstructure. Measurements were achieved under different loadings (cold compaction, free sintering, Hot Pressing (HP), and RS). Results show that conductivities evolutions are mainly driven by the contact conditions between particles. Bonding diffusion between particles and grain deformation was identified as the main mechanism, which can enhance the contact area between particles. This work will provide all the essential information to define the constitutive equations, presented in details in Part II, to describe the evolutions of the effective conductivities during sintering processes, such as RS or HP.