Titanium is a strong, low-density, corrosion-resistant transition metal used in aerospace, medical implants, and high-performance alloys. Its surface forms a stable oxide film that protects it from many chemicals.
The ground-state configuration is \([Ar]3d^2\,4s^2\). In compounds, Ti commonly exhibits +4 (e.g., TiO2, TiCl4) and +3 (e.g., Ti3+ violet solutions). Ti(IV) is d^0 (often colorless), while Ti(III) is d^1 and shows characteristic colors due to d–d transitions.
Titanium spontaneously forms an ultrathin, adherent layer of TiO2 that passivates the surface and heals rapidly if scratched. This passive film resists many chlorides and oxidizing acids. Simplified oxidation:
\(\mathrm{Ti(s) + O_2(g) \rightarrow TiO_2(s)}\)
In strongly reducing or fluoride-containing media, the film can be compromised.
Ore (ilmenite/rutile) is chlorinated to volatile TiCl4, purified by distillation, then reduced with molten magnesium:
The porous product is called titanium sponge, which is melted and alloyed.
They combine high specific strength (strength/weight), excellent fatigue and crack resistance, and outstanding corrosion resistance. Ti-6Al-4V (≈90% Ti, 6% Al, 4% V) is the workhorse alloy for airframes, turbine components (non-hot sections), and implants due to biocompatibility and modulus closer to bone than steel.
The stable TiO2 surface supports osseointegration (bone growth onto the implant), is chemically inert in body fluids, and resists corrosion. Surface treatments (sand-blasting, anodizing) can enhance roughness and bioactivity for better tissue attachment.
Titanium dioxide is a bright white, high-refractive-index pigment used in paints, plastics, and cosmetics. As a photocatalyst, anatase TiO2 (band gap \(E_g\approx 3.2\,\text{eV}\)) generates electron–hole pairs under UV light to drive redox reactions (e.g., self-cleaning coatings, pollutant degradation). Photon energy relates to wavelength by \(E=\tfrac{hc}{\lambda}\).
Yes. Anodizing in electrolytes grows TiO2 of controlled thickness. Light interference in the transparent film produces vivid colors without dyes; the perceived color depends on oxide thickness, which is set by the applied voltage.
Although Ti has great strength up to ~500–600 °C, at higher temperatures it suffers from creep and accelerated oxidation (\(\mathrm{TiO_2}\) scale growth). Nickel-based superalloys with strengthening precipitates (\(\gamma'\)) are used in the hottest turbine sections; Ti alloys are favored in cooler stages to save weight.
Titanium carbide and titanium nitride are hard, wear-resistant ceramic coatings (often gold-colored TiN) applied by PVD/CVD to cutting tools, dies, and biomedical devices. They reduce friction and extend tool life while adding corrosion resistance.
Titanium reacts with halogens on heating to give tetrahalides:
\(\mathrm{Ti(s) + 2\,Cl_2(g) \rightarrow TiCl_4(l)}\)
In air/water, the passive film protects Ti from many acids; however, HF (fluoride) and hot concentrated reducing acids can dissolve the oxide and attack the metal. Complexing fluorides form species like \([\mathrm{TiF_6}]^{2-}\).