A practical route for the characterization of zinc powder compacts with the aid of instrumented indentation and scratch tests

Abstract

In the current investigation the microstructural and mechanical properties of zinc compacted pallets were investigated. The pallets were compacted to different normalized densities (81–93%) under different pressures of 150, 200 and 450 MPa, respectively. The effect of sintering the samples under inert environment at 378 °C was also studied. Instrumented nanoindentation tests were utilized to deduce the mechanical properties of the compacted pallets. Nanoscratch tests were employed to qualitatively measure the sample resistance to plastic deformation. It was observed that there are two mechanisms driving the improvement of the mechanical properties. One mechanism is due to recrystallization driven by the increasing dislocation density and the other mechanism is due to consolidation of the particles into a continuous network due to diffusion and grain growth under high temperature sintering. The results also reveal that the mechanical properties and densities of the tablets are not linearly proportional to the compaction pressure. Higher compaction pressures resulted in denser tablets with higher elastic modulus and hardness. Upon sintering the compacts soften but also form a solid network due to the neighboring particles diffusion. Therefore, the hardness value drops but the reduced modulus increases. Furthermore, the nanoscratch tests revealed that higher compaction pressure produce not only a more compacted tablet, but also a more homogeneous one.