The influence of titanium sub-oxides in thermal sprayed coatings

Plasma spray and High Velocity Oxygen Fuel thermal spray processes have been used for achieving titanium oxide coatings under the current stoichiometry of titania. Reduced powders based in magnéli phases Ti_nO_2n-1 and slightly oxidized TiO_2-x were employed. A factorial design of experiments is included in this study for a better understanding of the influence in the operational parameters on the oxidation degree of titanium oxide during the spraying. In order to determine how the hardness of the coating is affected by the amount of the different sub-oxides, several matrices of nanoindentations have been made with the aim of correlate the dependence of the nanohardness values with the oxidation degree.