Effect of mixture composition, nanoparticle density and sound intensity on mixing quality of nanopowders

The present work is focused on the characterization of nanoparticles mixing under sound assisted fluidization. In particular, the effects of mixture composition, primary particles density and sound intensity on the mixing quality have been pointed out. The effect of the relative amount of the two powders has been investigated using Al2O3 and Fe2O3 nanopowders and carrying out tests at fixed acoustic field (130 dB–120 Hz) and varying the mixture composition (17, 50 and 77 wt% of Fe2O3). Whereas, the effect of nanoparticles density has been studied performing mixing tests between two denser powders, ZrO2 and CuO, at fixed mixture composition (50 wt% of ZrO2) and acoustic field (130 dB–120 Hz), and comparing the results with those obtained with the two lighter powders (Al2O3 and Fe2O3). Moreover, tests between ZrO2 and CuO have also been carried out at different sound intensities (130 and 140 dB), at a fixed frequency and mixture composition, in order to highlight the influence of SPL. Both the “global” and the “local” mixing between two different powders have been investigated by means of the Scanning Electron Microscopy with X-ray microanalysis (SEM/EDS) analysis of captured samples, in order to obtain the time dependence of the mixing degree, its asymptotic value and the mixing characteristic time.

The investigation on the sound efficiency to promote the mixing of two nano-sized powders, Al2O3 and Fe2O3, having a primary density of about 4000 kg/m3, has been carried out. In particular, the effect of the binary mixture composition has been highlighted by performing three tests with the application of a fixed acoustic field (130 dB–120 Hz) and varying the relative amount of the two powders (17, 50 and 77 wt% of Fe2O3). The influence of the nanoparticles density has also been pointed out by carrying out mixing tests between two denser powders, ZrO2 and CuO, having a primary density of about 6000 kg/m3.Figure optionsDownload as PowerPoint slideHighlights
► A suitable acoustic field was able to promote both “global and “local” mixing.
► The “global” and the “local” mixing occurred in different times.
► The “local” mixing was affected by the relative amounts of two nanopowders.
► The sound effectiveness was hindered by higher bed densities.
► The sound intensity had a beneficial effect on mixing quality.