Collection of liquid flame spray generated TiO2 nanoparticles on stainless steel surface

Nanosized titania (TiO2) powder has been generated using a turbulent H2–O2 flame with a spray of liquid Ti-precursor (TEOT). The collection was performed on a polished stainless steel surface inside the flame or outside the flame very close to the flame tip. According to the XRD-analysis, a large fraction of the titania was found to consist of anatase when collected further away from the flame but, when collected inside the luminous part of the flame, the material layer was seen to be gradually transforming into rutile. Also sintering of the sub 10 nm particles into larger particles on the collection plate was observed, mostly within the flame where the temperature zone was 1100–1500 °C. When utilising the process, formation of rutile can be avoided by performing the collection sufficiently far away from the flame tip. As a result of the study, an estimate of particle size on the collection substrate, crystal size and anatase/rutile fraction on different material production rates and as a function of collection distance can be given. Also an estimate for the rate of transformation from anatase into rutile can be given.