SPS titania coatings, with applications in water purification, were formed using continuous hydrothermally produced feedstocks for the first time. Coating photoactivity was compared with CVD and P25 analogues.

The photocatalytic capabilities of titanium dioxide are widely published. Reported applications of titania coatings include air purification, water purification and self-cleaning. Suspension spray has been highlighted as a possible route for the deposition of highly active nanostructured TiO2 coatings. Published work has demonstrated the capabilities of suspension plasma spray (SPS) and high velocity suspension flame spray (HVSFS), however, little work exists for suspension flame spray (SFS). Herein, these three suspension spray processes are compared as regards their capability to produce photocatalytic TiO2 coatings and their potential for industrial scale up. A range of coatings were produced for each process, manipulating coating parameters in order to vary phase composition and other coating characteristics to effect activity. Coatings produced were found to vary significantly between the processes with SFS highlighted as the most effective technique with regards to future scale-up and coating photoactivity. SFS coatings were found to be up to 5 times more active than analogous coating produced by CVD.

In this study, suspension HVOF spraying is used to deposit TiO2 nanoparticles on 304 stainless steel substrates. Spray parameters are varied, including spray distance and number of passes, to determine their effect on friction and wear properties as well as surface topography, microstructure, and phase composition. The spray parameters used, the microstructures observed, and the wear mechanisms of the nanostructured TiO2 coatings are described in the paper.

The photocatalytic properties of titania are widely known with applications including solar water disinfection, solar hydrogen production and as anti-bacterial surfaces. Herein, we report the use of suspension flame spraying for the deposition of conformal TiO2 coatings. This process is carried out using aqueous titania suspension (ca. 5 wt%) injected into an acetylene flame (ca. 3100 °C), via an atomiser. Coatings deposited were adherent, majority anatase phase and retained their nanostructure after coating. In this study the acetylene/oxygen ratio was altered to determine the effect on the photoactivity of titania coatings produced, with photoactivity determined by photocurrent generation under illumination. All coatings produced were shown to be photoactive with a marked difference in photocurrent observed between coatings produced in the varying flame conditions. Photocurrent generation increased by up to 3.7 times with decreasing fuel ratio. This difference was attributed to the build-up of reduced titania species in the coating.