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outline essentially higher corrosion rates for the initiation stage of corrosive process, in the case of unprocessed steel 45 without a graphite pellicle (Figure 10, curve 2). Afterwards, with the passing of time, the process of corrosion is attenuated; the

Corrosion speed variation depending on the time of immersion [28]: (1) steel С45 covered with graphite and

Similarly, with the passing of time, the nature of the corrosion product is modified; oxides are most likely formed, having a low oxygen content and being more

Simultaneously, it is acceptable that corrosion products form films on the metal surface that insulate the metal from corrosive agents. For this reason, the curves

These films are adherent and also compact enough so that the corrosion process

It should be noted that the determinations were made in a static regime. In dynamic conditions, the formed oxide film can probably detach from the metal surface, and, in this case, the corrosion process is conducted with higher corrosion

In the case of steel coated with graphite film, lower corrosion rates are found; afterwards, they begin to rise due to degradation of graphite film, as a result of its

Experimentation established that in acid solution of 30% HNO3, after 3 min, the amount of uncovered graphite steel electrochemically dissolved 1.4 times greater than graphite-coated steel—1.3 times greater in 10 min. In salt solution of 1% NaCl, the amount of uncovered graphite steel electrochemically dissolved was 1.2–1.4

Analysing the results of the experimental researches, we can conclude the

• Thermal treatment, in the absence of liquid phase formation on the processed surface, can be performed only in the regime of maintenance of the electrical

• Under superficial processing conditions, with the maintenance of electric spell released on "cold" electrode spots, the mass transfer in the solid phase can

determined corrosion rate is smaller, when the time of immersion is longer.

showing the variation of corrosion rate time show a trend of flattening.

times greater than graphite-coated steel deposited by PEDM.

discharge in impulse on "cold" electrode spots.

stable (Fe3O4) (FeOFe2O3).

rates.

Figure 10.

(2) unprocessed steel С45.

Corrosion Inhibitors

destruction.

4. Conclusions

following:

114

diminishes in time, but does not annihilate.

Pavel Topala\*, Alexandr Ojegov and Vitalie Besliu Alecu Russo Balti State University, Balti, Republic of Moldova

\*Address all correspondence to: pavel.topala@gmail.com

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
