Origin of preferential orientation of rutile phase in thermally sprayed TiO₂ coatings

In order to elucidate the origin of the (101) preferential orientation of rutile phase in thermally sprayed TiO₂, both plasma spraying and high velocity oxy-fuel spraying of TiO₂ were conducted. The rutile phase in plasma-sprayed TiO₂ presented a much more significant preferential orientation than that in high velocity oxy-fuel sprayed TiO₂. The significant difference in the surface morphologies of both deposits suggests that the orientation factor is significantly influenced by the tensile stress in the individual splats. (101) planes may change their orientations parallel to the coating surface under tensile stress at high temperature during splat cooling. The crystalline plane rotation leads to the preferential orientation of the rutile phase in thermally sprayed TiO₂ deposit.