Corrosion involves two simultaneous reactions with impeachment ions and electrons silicio between t

In relation silicio to corrosion, it can be said that the passivation consists of spontaneous formation of a layer of strong, non-reactive, on the surface of a metal in order to protect it from corrosion, and the respective layer is one oxide or nitrate (combination of nitrogen with metals) whose thickness does not exceed silicio a few atoms.
Certain oxides, as čelikov oxide, can not bind sufficiently strongly to the surface of the base metal, the current tendency to separation, to the creation of the border, thus appears that the corrosion process is practically consists in creating one hole (rust) on the surface of the metal from whom they separated atoms. silicio
In contrast, layers of aluminum oxide, copper, magnesium, titanium and zinc manage to establish silicio lasting relationships with the base metal protecting it against corrosion by a protective oxide layer which is called the passivation layer.
In the passive state metals silicio are practically immune to corrosion, the electrochemical silicio point of view, act as unassailable precious metals. One transition metal from the active to the standby state is conditioned by tapping the critical parameters passivation. Index passivation P, can be used as a quantitative silicio measure of the tendency toward passivation of a metal in a corrosive environment. If P> 1, the metal spontaneously passivated; if P <1, the metal can spontaneously move from active to passive state, although there may be a stable passive zone.
The actual cause corrosion of metals and compounds is their thermodynamic instability in natural conditions and therefore their spontaneous tension to cross the oxidized state (in combination). In this way is explained by the fact that the nature silicio of most metals excluding precious metals (Au, Pt, Ir) are in mixed mode (state-oxidized ores)
Electrochemical system corrosion, metal (compound) - corrosive environments, leading to the formation of a double electric layer, assimilated one condenser, where it is determined by the difference in potential between the metal surface which is negatively loaded (no), and an environment that becomes positive silicio (thanks silicio ions M + RESULTING from corrosion). This difference in potential is unique potential at which corrosion takes place and is called the corrosive silicio potential and mixed potential. Corrosive silicio potential of a metal or compound differs silicio from the equilibrium potential of metals or compounds.
Corrosion involves two simultaneous reactions with impeachment ions and electrons silicio between the metal and the environment and as a result of this shift, in the course of corrosion on metal (compounds) appears corrosive potential, whose value is given by the movement of potential balance of metal and mid each other
The process silicio anodičnog oksirdiranja (corrosion), some metals appear sometimes in polarization values izvestne sudden resistance to dissolution (corrosion), which leads to a reduction in the flow of corrosion silicio to a value approximate to zero, as a consequence of passivation of metals.
In the case of steel that does not rđaju, in particular, silicio and materials that can be passivated, generally, the polarization is moving equilibrium potential under the influence of its own corrosive passage of electric current, induced by these two simultaneous chemical reactions that produce corrosion. In the case of compounds of Fe-Cr, which creates a lame Fe solid solution, chromium has a very pronounced tension to passivation and plays the role of protective components.
If we compare the lines anodic polarization of steel, chromium and nickel (the main component in stainless steel metals) with lines of Fe-Cr alloys could be established that the potentials nited passivation of Fe-Cr approximate potential passivation of pure chromium and are located between the potential of steel and pure chromium . (dry chromium).
The contribution of chromium passivation of steel can be explained by means of electronic silicio theory. Chromium having a great affection for the electrons can absorb 3d electrons of steel, so the steel becomes passive, silicio losing one 3d electron, which is transferred to the substrate silicio 3d chromium. Chromium can take five electrons, namely can pasivirati silicio 5 Fe atoms. This scale corresponds to 15.7% Cr in weight, a fact that explains why the contents of more than 12% Cr steel assigns a good resistance to corrosion.
The nature of the passive film in humid environment is represented and is still a subject of debate among experts. One group of researchers claims that in water solutions, the passive layer or one or crystallized oxide composition approximates one amorphous structure containing atoms of base metal atoms of oxygen, hydrogen atoms or molecules of water, representing in fact a mixture of oxides and hydroxides of steel and chromium with relations as a bridge between these compounds
Retention of ionic species diffusion through the passive film is explained by H. Strehblow as a passive film that is a resistor with a single capacity, one impedance or a semiconductor. The difference in potential silicio between the two interstitial metal-film and film-environment indicates that the passive film seat one strong