Preparation, characterisation and corrosion behaviour of protective coatings on stainless steel samples deposited by plasma detonation techniques

Plasma-detonation techniques have been used to modify the surface of austenitic stainless steel samples in order to improve their corrosion resistance. Deposition of Al2O3 coatings in combination with high current electron beam treatment and deposition of titanium nitride (TIN) were applied for this purpose. The characterisation of the samples was performed using nuclear reaction analysis and Rutherford backscattering spectroscopy. The corrosion behaviour of the samples was investigated in H2SO4 using electrochemical techniques (cyclo-voltammetry and potentiodynamic polarisation). The values of the critical and passivation current density as well as of the corrosion, passivation and re-passivation potentials, showed a considerable increase of the corrosion resistance of the coated steel samples. This improvement is connected with the properties of the modified region (thickness, adhesion). The surface morphology and microstructure of the specimens before and after the corrosion experiments were investigated by X-ray diffraction, scanning and transmission electron microscopy