Corrosion properties of plasma electrolytic coated samples

Abstract

Purpose -Plasma electrolytic saturation (PES) treatments were applied on the surface of AISI H13 steel and corrosion resistance of the treated samples was investigated using electrochemical test methods. The aim was to obtain optimal corrosion resistance of the differently treated samples. Design/methodology/approach -Nitrocarburized and boride layers were produced on AISI H13 steel by the means of the PES technique. Different experimental parameters during each treatment provided different microstructural and electrochemical properties. The techniques used in the present investigation included X-ray diffraction, SEM, potentiodynamic polarization measurements and electrochemical impedance spectroscopy (EIS). Findings -The plasma electrolytic nitrocarburising coating was characterized by lower integrity than a PEB coating. All PES coated steels had a noble electrochemical behavior compared to the untreated steel. Different nano-structures and morphologies obtained by different experimental parameters produced different electrochemical behaviors. Practical implications -The results obtained in this research into PES techniques can be used wherever good corrosion resistance with the highest efficiency is required. Originality/value -The speed of treatment by plasma electrolytic saturation techniques makes this method very suitable for industrial production of components.

Evaluation of morphological and tribological properties of nanocrystalline nitrocarburised coating produced on AISI H13 carbon steel by pulsed plasma electrolytic saturation (PPES) technique

“…Moreover, their surface is significantly smoother than that of the conventionally treated samples. 3 The formation of nanocrystalline coatings depends on the time off t off period in which the current is interrupted. 3 During this period, desorption of impurities and renucleation make new and finer grains to form.…”

“…3 The formation of nanocrystalline coatings depends on the time off t off period in which the current is interrupted. 3 During this period, desorption of impurities and renucleation make new and finer grains to form. Consequently, the smaller grain sizes lead to more uniformity in the grain distributions.…”

“…Consequently, the smaller grain sizes lead to more uniformity in the grain distributions. 3 On the other hand, according to the Hall-Petch relationship, a larger average grain size attributes to more grain dislocation pile-up at the grain boundaries. In addition, it indicates that an increase in hardness is mainly obtained due to the nanocrystalline grain refinement.…”

“…The plasma electrolytic processes have been successfully used for nitrocarburising low alloy ferrous materials, such as mild steels 2. The authors’ previous studies3 have indicated that the experimental parameters play a considerable role in the obtained surface properties. Consequently, different morphologies of the nanocrystalline coatings were obtained from different experimental parameters.…”

“…Consequently, different morphologies of the nanocrystalline coatings were obtained from different experimental parameters. Variables such as pulse currents and duty cycles are the most important factors in providing desirable surface characteristics 4…”