Surface Features Changes and Corrosion Stability of Titanium Surfaces by Suitable Treatments

Abstract

Keywords: titanium, TiO 2 film, surface treatments, corrosion stability Titanium is the ninth of the most common elements in the Earth's crust, with a crustal abundance of 0.5% (or 0.8% as titanium dioxide) The exposed surface of the titanium is however attacked by corrosion in the first part of the exposure at environment, but the growth of a naturally protective oxide layer (less than 10 nm thick) can prevent its degradation. When titanium is in a fully passive state, the corrosion rates in aqueous media are typically below 40 μm/year, a value much lowered as compared to the value of 130 μm/ year that is generally accepted by designers as standard for general corrosion The oxide layer occurred in direct contact with the Ti surface consists of TiO; the intermediate layer is composed of Ti 2 O 3 and the outer layer is TiO 2 To improve the stability and other functional properties of the oxide protective layer, and to change the surface morphology for various applications, the oxide layer is grown by different techniques leading to different morphologies and surface characteristics. For Depending on the preparation method, experimental conditions, and target applications, TiO 2 has a large variety of presentation forms: nanoparticles, nanorods, nanowires, nanotubes, under columnar or compact films and can be obtained in amorphous form or in three crystalline phases: anatase, rutile, and brookite. For each type of application there are some important properties for TiO 2 that are essential. As the most promising photocatalyst, TiO 2 materials have already an important role in solving many serious environmental and pollution challenges In medical applications, TiO 2 is used firstly as coating for Ti and Ti alloys to assure the protection against corrosion and secondly, a tissue-friendly nanostructure is designed in order to facilitate the integration of material in body In this work, three different techniques will be presented that deal with the formation of a thin layer of TiO 2 , which beside the protective aspects will be followed by properties that are valuable in the context of today's self-renewing energy or that responding to modern biomedical needs. These techniques (Chemical Vapour Deposition, anodic oxidation and laser treatment) have some advantages in the growth stages, and produce films with different properties which recommend them for specific applications