Titanium dioxide (TiO2) is an attractive material for numerous technological applications such
as photocatalytical applications. These materials can in some conditions have the ability to allow the environmental
purification of air and water by the decomposition and removal of harmful substances, such as
volatile organic compounds (VOC), benzene compounds, NOx, SO2, etc. Our work was focused on the elaboration
and the evaluation of the environmental properties of titanium dioxide coatings by plasma spray
techniques. The principle of plasma spraying consists by the injection in an enthalpic source (plasma) of the
powder of one material to be sprayed. The molten powder is transported and accelerated by the plasmaproducing
gas flow and crushed on the target substrate, where the particles of material solidify with high
speeds, thus forming the coating. The advantages of thermal spraying consist in the fact that the coating has
stability, durability, adherence and cohesion. For this study, the initial powder material was an anatase TiO2.
The photocatalyst coating was realized by a few kinds of thermal spray method: gas flame, APS (atmospheric
plasma), VPS (vacuum plasma) and HVOF (high velocity oxygen fuel). The microstructures of the deposits, as
a function of the coating process, are analysed by optical microscopy, scanning electronic microscopy, and
the X-rays diffraction. To carry out the step of validation of these surfaces for their environmental functionalities,
we used a control test process for the photocatalytic effectiveness with respect to nitrogen oxides.
For that an original test chamber has been developed. Ultraviolet rays irradiated the coating specimens and
the efficiency of NOx elimination has been controlled using a gas analyser. We studied the photocatalytical
properties of different obtained coatings as a function of various parameters (porosity, thickness, ratio
anatase/rutile).
