Francesco Casari

SPS, binderless WC powders, and the problem of sub carbide

Binderless tungsten carbide powders can be sintered to full density using spark plasma sintering through a combination of high heating rates and pressure. But although the pathway looks promising, there can be problems…

Microstructure and Mechanical Properties of Nanostructured Aluminum Consolidated by SPS

Nanostructured aluminum powders were obtained by means of planetary ball milling with methanol as the Process Control Agent (PCA). The behavior, during milling, was considered measuring the microhardness and grain size at different milling times. Bulk near-full density samples were sintered using the Spark Plasma Sintering technology with different schedules: temperature of 500°C and 550°C, pressure of 30 MPa and 60 MPa and different modes of applying the pressure were changed in order to understand the behavior during sintering. The samples sintered at 500°C showed a density of about 2.4-2.61 g/cm3 while for that sintered at 550°C it was 2.65-2.67 g/cm3 depending on the applied pressure. All the samples retained their nanostructure with an increase of the grain size from about 46 up to 70-90 nm. Using X-ray diffraction and metallography the formation of Al4C3 carbides was detected for samples sintered at highest temperatures.

Design of Layered Metal‐Ceramic FGMs Produced by Spark Plasma Sintering

The production of layered Nickel‐Alumina FGMs by means of Spark Plasma Sintering is studied by investigating the effect of sintering under temperature gradient on final properties, i.e. density, hardness and fracture toughness. Results demonstrate that alumina powder can be fully densified at 1400 °C, whilst a temperature of 1050 °C is sufficient to consolidate nickel powder. The temperature gradient, obtained with the proper design of the die configuration, is useful for reduction of thermal stresses, but does not permit the full consolidation of the intermediate layers.