The oxidation degree of a commercial silicon carbide (SiC) powder was studied by means of Fourier transform infrared spectroscopy, using the intensity of the (SiO2) band at 450 cm-1 for measurements. Results are related to data obtained by LECO and gravimetric measurements. The influence of water in oxygen on the rate of the oxidation process was particularly examined. It was found that water alone had an oxidizing efficiency and that its mixture with oxygen increased the effect of the latter. The presence of Rh particles on SiC promoted the formation of SiO2. However, as shown by the IR study of CO adsorption, this formation embedded the metal particles. This effect can be avoided by loading Rh on a precalcined SiC sample.
We introduce a flame based aerosol method to fabricate thin films consisting of binary TiO2/SiO2 nanoparticles deposited directly from the flame onto the paperboard. Nanocoatings were prepared with Liquid Flame Spray (LFS) in a roll-to-roll process with the line speed of 50 m/min. Surface wetting behavior of nanocoated paperboard was studied for different Ti/Si ratios in the precursor, affecting TiO2/SiO2 ratio in the coating. Wettability could be adjusted to practically any water contact angle between 10 and 160° by setting the Ti/Si ratio in the liquid precursor. Structure of the two component nanocoating was analysed with FE-SEM, TEM, EDS, XPS and XRD. The porous thin film coating was concluded to consist of ca. 10 nm sized mixed oxide nanoparticles with segregated TiO2 and SiO2 phases. Accumulation of carbonaceous compounds on the surface was seen to be almost linearly dependent on the Ti/Si ratio, indicating of each species being exposed in corresponding amount. However, wetting of the surface was observed to follow merely an S-shaped curve, caused by the roughness of the nanocoated surface. Reasons for the observed superhydrophobicity and superhydrophilicity of these binary nanocoatings on paperboard are discussed.