On-line tools for microscopic and macroscopic monitoring of microwave processing

Abstract

Direct monitoring of temperature, chemistry and microstructure is required to understand microwave heating in more detail, in order to fully exploit the unique features this non-equilibrium processing method can offer. In this paper, we show first that microwave radiometry can be used to follow volumetrically the thermal trajectory of microwave-heated aluminium powder. In-situ Raman spectroscopy is then shown to evidence thermal gradients between diamond and silicon grains in a binary powder mixture. Finally, perspectives and preliminary results of microstructural analysis obtained from X-ray microtomography are presented. r

PCA reduced Gaussian mixture models with applications in superresolution

“…Corollary 2. Let (U (r) ) r be generated by (29) with τ (r) ≥ γL, where L is the Lipschitz constant of ∇H and γ > 1. Consider the sequence generated by PALM with (29).…”

Raman Spectroscopy

“…Vaucher et al solved this problem by making interesting use of the temperature dependence of Raman spectra to deliberately turn their fi ber -optic Raman probe into a specialized thermometer by monitoring the changes in the phonons of a silicon and diamond powder mixture as it was heated up to approximately 750 ° C [140,141] . It would be useful to know the temperature in each phase of a heterogeneous mixture, instead of the average temperature, since different materials respond differently to microwave heating.…”

Mechanism of SiC crystals growth on {100} and {111} diamond surfaces upon microwave heating

“…The diamond-SiC composites can be fabricated via hightemperature high-pressure sintering of diamond and Si [6-9], infiltration of diamond compacts with precursor gas [10] and more recently by microwave reactive sintering of diamondsilicon powders mixtures [11,12]. In contrast to the conventional processes, microwave sintering has the advantage of internal and phase-selective heat generation which offers high sintering rates [13].…”

“…Numerous investigations have been carried out on the structure of SiCdiamond interfaces [5][6][7][8][9]. However, to the best knowledge of the authors, the growth mechanism of SiC crystals grown on differently oriented diamond surfaces has not been studied and experimentally verified.The diamond-SiC composites can be fabricated via hightemperature high-pressure sintering of diamond and Si [6-9], infiltration of diamond compacts with precursor gas [10] and more recently by microwave reactive sintering of diamondsilicon powders mixtures [11,12]. In contrast to the conventional processes, microwave sintering has the advantage of internal and phase-selective heat generation which offers high sintering rates [13].…”