Short-term (1–2 s) hot bulk plastic deformation of commercially pure titanium VT1-0 was studied at 25, 500, 600 and 700 °C without post-deformation annealing. Optical metallography, XRD line-profile analysis and Vickers micro-hardness testing were used to characterize the as-deformed structural state. The α-Ti single-phase structure was retained across the entire temperature range. Both microhardness and grain size evolved non-monotonically: hardness ranged from 161.7 ± 11.2 HV at 600 °C to 184.5 ± 10.8 HV at 700 °C, while grain size varied between 21.5 and 24.9 μm against 36.5 μm in the initial material. Such non-monotonic hardness evolution with deformation temperature is consistent with the interplay between deformation strengthening and thermally activated softening reported for CP-Ti processed under other conditions. The fitted FWHM of the α-Ti (101) reflection ranged from 0.463° to 0.738° in the deformed specimens, compared with 0.24° in the as-received reference. Size-related and strain-related broadening were not separated, precluding a unique interpretation of these differences in terms of coherent-domain size or defect structure. Hardness evolution cannot be attributed to grain refinement alone. Thermally activated restoration processes may contribute to the observed differences; however, the present measurements do not establish the underlying mechanisms. Among the investigated specimens, the specimen processed at 700 °C exhibited the highest mean microhardness. This observation does not establish an optimal processing temperature or an optimum across other material properties.

Commercially pure titanium is widely used for load-bearing implants but its low surface hardness and high friction coefficient limit durability. In this work, calcium- and silicon-bearing coatings were deposited on CP-Ti (VT1-0/ASTM Grade 2) by micro-arc oxidation (MAO) in an aqueous electrolyte of 30 wt.% H₃PO₄, 60 g/L hydroxyapatite and 75 g/L wollastonite, at a fixed filling-parameter setting of 8% and two voltages, 200 and 300 V. The coatings were characterised by SEM, EDS, FIB cross-sectioning, progressive-load scratch testing, instrumented indentation (ISO 14577-1) and single-pass ball-on-flat sliding with 3D profilometry. Raising the voltage from 200 to 300 V thickened the layer from about 28 to 37 µm but rendered the cross-section coarsely porous and the coating–substrate interface markedly rougher. The first cohesive critical load fell from 6.15 N at 200 V to 3.73 N at 300 V, and the kinetic friction coefficient rose from 0.41 to 0.75. Instrumented indentation gave comparable properties for both coatings (Martens hardness 2254 versus 2169 N/mm²; modulus 103 versus 102 GPa), indicating that the higher-voltage penalty lies in coating architecture and interface quality rather than in intrinsic hardness. The lower voltage is therefore preferable for tribologically loaded coatings of this type.