Inherent heating instability of direct microwave sintering process: Sample analysis for porous 3Y-ZrO2

International audienceDirect microwave heating of 3Y-ZrO 2 is studied at frequency of 2.45 GHz. Different conditions of input power, sample position and size are tested. For the first time, the experimentally known instability of microwave sintering is explained coupling the effective medium approximation and finite-element method. We show how the material dielectric permittivity imaginary part which increases with temperature and relative density encourages high hot spot phenomena. It is shown that the sample location has a great impact on th

Microwave sintering and characterization of polypropylene/multi-walled carbon nanotube/hydroxyapatite composites

Low dielectric property of polypropylene (PP) is the main barrier to microwave sintering of PP. In this study, 1 wt% of multi-walled carbon nanotubes (MWCNTs) were incorporated into the PP as the microwave susceptors, together with different amounts (0, 5, 15, and 30 wt%) of hydroxyapatite (HA) to produce PP/MWCNT/HA biocomposites for bone tissue engineering by microwave sintering. A reduction of fabrication time (within 1 min) was achieved and the sintering time decreased with an increase of the HA content. The existence and homogeneous distribution of the HA in the sintered composites were confirmed by X-ray diffraction and back scattered scanning electron microscopy, respectively. Microstructures of these composites were examined and thermal analyses were carried out. The microwave sintering technique developed in this study can be used as an alternative to conventional polymer processing methods for fabrication of microwave transparent PP based composites