Speaker
Description
Fabrication of technical ceramics involves three matin steps: synthesis of powder, shaping and sintering. This last step is generally defined as a transformation of compacted powder into a solid with progressive removal of porosity using heat [1]. The driving force of sintering is the reduction of interfaces. It can occur by densification (replacement of solid/vapour interfaces by solid/solid interfaces) and by grain coarsening, as illustrated in Figure 1. The formation of necks during solid state sintering is attributed to differences in the curvature of grains and necks. The latter is the driving force for mass transport. Movement of matter occurs by diffusion of species. Different paths of diffusion are possible ; some of them are considered as densifying diffusion mechanisms when they contribute to the densification of materials.
Different parameters related to the material and the process have an influence on the final density and microstructures of a sample. The parameters related to the material are chemical composition, powder’s characteristics (particle size, shape and size distribution). The parameters related to the process are temperature, heating and cooling rates, duration, atmosphere and presence of pressure. Minimization of material, time and energy waste is mandatory in all production processes due to environmental concerns. To this aim, different non-conventional sintering processes have been developped and studied as an alternative to conventional sintering (i.e., sintering in a resistive furnace) to decrease the environmental impact of sintering [2].
This presentation will be divided in two main parts:
• a general overview about sintering, densification and evolution of microstructures
• a focus about some projects carried out in LGF about non-conventional sintering by microwave heating and sintering of recycled powders.