Synthesis of anodized films of TiO2, chromium-doped TiO2 and cobalt-doped TiO2 for structural, hardness and friction coefficient analysis

Titanium sheets were anodized using a solution composed of HCl, ethylene glycol, and deionized water. To incorporate the doping elements, the salts K2Cr2O7 and Co(NO3)2<middle dot>6H2O were added individually. The anodized sheets were heated to 600 degrees C, leading to a combination of anatase and rutile. A decrease in the intensity of the Raman spectra in the anatase/rutile vibrational modes indicated a reduction in crystallite size, which was corroborated by the Scherrer approximation. X-Ray Photoelectron Spectroscopy demonstrated the presence of 2p titanium and 1s oxygen in all samples, 2p chromium for the doped sample, and lower energies in the titanium and oxygen bands for the cobalt-doped sample. The calculation of the residual stresses revealed that the doped films presented higher compressive stresses, which led to higher Vickers microhardness values. It was possible to observe a decrease in the coefficient of friction of 50% for the doped samples compared to the undoped one.Graphical AbstractEffect of dopants on the TiO2 lattice