Heat treatment and surface modification with a layer of titania (TiO₂) and TiO₂-SiO₂ composite coating with varying compositions (from 0 to 40 mol% SiO₂) by sol gel dip coating technique on 2205 duplex stainless steel. As a precucer for titania, titanium isopropoxide, for silica, tetraethyl orthosilicate were used and hydrochloric acide as a catalyst, ethanol as solvent and diethanolemaine as dispersant microstructure analysis after heat treatment was studied SEM, XRD. The FESEM was used to analyses the coating’s morphology microscopically and EDS. Also surface roughness and contact angle were evaluated. The corrosion resistance of DSS in Ringer’s solution was investigated by photodynamic polarization. The study aims to assess DSS’s capabilities for bio applications to replace austenitic grades. The heat treatment gives a balanced microstructure and no precipitation of secondary phases. The sol-gel approach proved effective in producing a homogenous and dense layer of titania and composite coatings, increased roughness after coating therefore reducing the contact angle and making it more hydrophilic, making it suitable for bio application with the nano composite coating producing the best results. It is due to its smooth surface increase film thickness and results showed that sol-gel composite coatings greater bioactivity and enhanced the corrosion resistance of DSS substrates, with the highest improvement percentage (91.95%) at C2 specimen.

Keywords: Duplex stainless steel, Heat treatment, TiO₂-SiO₂, Sol gel, Coating.