Neck growth kinetics during microwave sintering of copper

Effect of sintering on the reactivity of copper-based oxygen carriers synthesized by impregnation

“…From the measurements at different temperatures shown in Figure 9, an activation energy value of 199 ±15 kJ/mol for Ƙሺܶሻ was calculated, which belongs to the range of activation energies for lattice diffusion of metallic copper found by other authors (180 to 222 kJ/mol [5]). Furthermore, the best fit with the experimental data was obtained with ݉ = 3.3, which is very close to what has been reported in the literature for the lattice diffusion mechanism (݉ =3 [37]).…”

“…Nevertheless, García-Labiano [4] and Maya & Chjene [3] modeled the redox reactions of OCs particles and they calculated temperature increases within the OC particle to be less than 10 K during oxidation. Hence, De Diego et al [1] ruled out the possibility of copper sintering due to OC particle temperature increase, although at the bulk temperature at which these authors performed their experiments (T=800 °C), metallic copper has a significant sintering rate [5].…”

Initial stage sintering of binderless tungsten carbide powder under microwave radiation

“…A series of classical neck growth kinetics experiments was conducted using sphere-to-sphere approach [13], in order to investigate diffusion mechanism that controls initial stage of microwave sintering. A monolayer of free packed tungsten carbide particles was placed on microwave transparent mullite substrate, which was then placed inside the insulation package.…”

“…Sintering experiments were carried out using a 6 kW, 2.45 GHz multimode microwave cavity. No additional susceptors were used in the experimental setup, so that the heating was pure microwave heating, detailed information of the experimental set-up is presented elsewhere [13]. Inert atmosphere was maintained during sintering process by first creating a vacuum of 8-10 Torr inside the furnace by back filling ultra high purity (UHP) nitrogen.…”

“…Some theoretical work was made by using classic flat-ball model for initial stage of conventional sintering and comparing it with data for microwave sintering [12]. Application of sphere-to-sphere model during microwave sintering of copper powder [13] was made, revealing some anomalous neck growth rate during microwave sintering process. These works indicate that experiments for initial stage of microwave sintering could be a missing link to explain the nature of entire microwave sintering process.…”