Structure of combustion aerosols

Morphological Characterization of Fumed Silica Aggregates

“…These authors did not compensate for partial obscuration, resulting a modest underestimation of the fractal dimension. The value found here is also consistent with that determined by the majority of the scattering studies, where values typically range from 1.7-2.0 for Cab-OSil (Hurd et al 1987;Schaefer and Hurd 1990;Schaefer et al 1991) and 2.0-2.2 for Aerosil (Kammler et al 2004;Khan and Zoeller 1993;Saint-Michel et al 2002;) fumed silicas. This analysis further confirmed that the pre-factor is on the order of 1, as has often been assumed for fractal aggregates.…”

“…Fumed silica has been the subject of many studies, including early determinations of its fractal nature by microscopy (Forrest and Witten 1979;Forsman et al 1987) and by scattering (Hurd 1990;Hurd and Flower 1988;Martin et al 1986;Schaefer and Hurd 1990;Schaefer et al 1991). The details of the structure within the aggregate, however, are less well understood.…”

Generation and investigation of airborne silver nanoparticles with specific size and morphology by homogeneous nucleation, coagulation and sintering

“…Final morphology and structure of the generated agglomerates strongly depends on competition between collisional growth and sintering (Yang & Biswas, 1997), leading to either spherical or fractal-like particles. Schaefer and his colleagues have shown combustion aerosol morphologies of fumed silica to be fractal-like, with a fractal dimension of 1.8 (Schaefer & Hurd, 1990;Schaefer et al, 1991Schaefer et al, , 1994. Yang and Biswas (1997) observed that sintered nanosized titania agglomerates in flames were still agglomerated having fractal dimensions in the range of 1.7-1.8, even at higher sintering temperatures (sintering temperature ratio to the melting point of bulk titania (2123 K) was reported 0.73 (1544 K)).…”

Measurement of Fractal Aggregates of Polydisperse Particles Using Small-Angle Light Scattering

“…This technique is limited to characterizing aggregates of fractal dimension less than 2. Static scattering, such as smallangle X-ray scattering (SAXS) (13)(14)(15)(16)(17), small-angle neutron scattering (SANS) (18)(19)(20), static light scattering (21)(22)(23)(24)(25)(26), is the most popular tool for measuring the fractal dimension. The mass fractal dimension is obtained from the scaling of the aggregate scattered intensity with the wave vector (q, a function of scattering angle).…”