Search results for " Passive film"

Characterization of Thin Passive Film-Electrolyte Junctions. The Amorphous Semiconductor (a-SC) Schottky Barrier Approach.

2017

A detailed study of the electronic properties of thin (< 20 nm) anodic TiO2 potentiostatically grown on titanium in two different solutions is presented. The results show that the nature of the anodizing solution affects the electronic properties of the anodic film and in particular the density of electronic state (DOS) distribution. Different DOS were derived from the experimental data analyzed according to the theory of amorphous semiconductor (a-SC) Schottky barrier. It is shown that the usual non-linear and frequency dependent Mott-Schottky plots are in agreement with expected theoretical behaviour of a-SC Schottky barrier. It is shown the importance of the DOS distribution in determini…

Photoelectrochemical monitoring of rouging and de-rouging on AISI 316L

2017

Electrochemical conditions for inducing rouging on surface of AISI 316L in quasi neutral aqueous solution are studied. Potentiostatic polarization at 0.6 V vs. SSC at pH ∼ 7 allowed growth of colourless passive films with a band gap slightly lower than that estimated for the oxide grown on the SS surface by air exposure due to chromium dissolution. Under stronger anodic polarization (UE = 1.5 V vs. SSC) coloured passive films are formed, mainly constituted by iron oxide according to their band gap (Eg = 2.0 eV). Etching in citric acid at 60 °C results to be effective in removing rouging.

Effect of alloying elements on the electronic properties of thin passive films formed on carbon steel, ferritic and austenitic stainless steels in a …

2014

The influence of alloying elements on the electrochemical and semiconducting properties of thin passive films formed on several steels (carbon steel, ferritic and austenitic stainless steels) has been studied in a highly concentrated lithium bromide (LiBr) solution at 25 °C, by means of potentiodynamic tests and Mott Schottky analysis. The addition of Cr to carbon steel promoted the formation of a p-type semiconducting region in the passive film. A high Ni contentmodified the electronic behaviour of highly alloyed austenitic stainless steels.Mo did notmodify the electronic structure of the passive films, but reduced the concentration of defects.

Use of Mott-Schottky Plots to Characterise the Amorphous Passive Film/Electrolyte Junction

2010

A Critical Analysis on the Use of Mott-Schottky Plots to Characterise the Passive Film/Electrolyte Junction

2010

Effect of Composition on the Photoelectrochemical Behavior of Anodic Oxides on Binary Aluminum Alloys

2006

The photoelectrochemical behavior of anodic films on Al alloys, containing titanium, tantalum, and tungsten (valve metals), has been studied as a function of alloy composition and anodizing conditions. Photocurrent spectroscopy has been used to get information on bandgap and the flatband potential values of different mixed oxides. Both insulator-like and semiconducting behavior has been observed for anodic oxides grown on Al-W and Al-Ti alloys dependent on alloy initial composition. Optical bandgap values, E opt g , of different oxides are in accordance with predictions based on the correlation between E opt g and the difference of electronegativities of the oxide constituents, indicating p…

Influences of Structure and Composition on the Photoelectrochemical Behaviour of Anodic Films on Zr and Zr-20at.%Ti

2008

Abstract A photoelectrochemical investigation on anodic films of different thickness grown on sputter-deposited Zr and Zr–20 at.%Ti was carried out. The estimated optical band gap and flat band potential of thick ( U F  ≥ 50 V) anodic films were related to their crystalline structure and compared with those obtained for thinner ( U F  ≤ 8 V/SCE) anodic oxides having undetermined crystalline structure. The E g values obtained by photocurrent spectroscopy were also compared with the experimental band gap estimated by other optical ex situ techniques and with the available theoretical estimates of the zirconia electronic structures in an attempt to reconcile the wide range of band gap data rep…

Photoelectrochemical Techniques in Corrosion Studies

2005

Physico-chemical characterization of passive films on 316L stainless steel grown in high temperature water

2014

A Chemical Approach to the Modelling of Band Gap of Passive Films for Corrosion Studies

2015

Photocurrent Spectroscopy (PCS) has gained a large consideration in the last decades as in situ technique for the characterization of semiconductors and photoconducting passive film/electrolyte junctions being able to provide information on the location of characteristic energy levels like: flat band potential (Ufb), internal photoemission threshold (Eth) and band gap value (Eg)