جستجوی مقالات مرتبط با کلیدواژه « اکسیداسیون پلاسمایی الکترولیتی » در نشریات گروه « فنی و مهندسی »

In recent years the Plasma electrolytic oxidation (PEO) coatings on Mg, Ti and Al substrates are widely investigated. One of the important parameters which affects these coatings properties is the electrical current which used in the process. However, in this study the effect of frequencies over 1000Hz on corrosion behavior and microstructure of PEO coated samples of Mg AZ31 was investigated. The samples have been coated in a basic bath with 10g/l Na3PO4 and 2g/l KOH under DC pulsed unipolar current with 12% duty cycle in 1000, 2000, 3000Hz frequency. Microscopy investigations of surface and cross sections of samples showed no significant difference between three samples. Also, the X-Ray Diffraction studies showed Mg and MgO as dominant phases of all coatings and there were no phosphate containing phases in the coatings. The electrochemical tests including OCP, Potentiodynamic polarization and EIS showed superior corrosion resistance for 2000Hz sample and it concluded that this sample may be the optimum specimen.

Nanocomposite coating was applied on commercial pure titanium using plasma electrolytic oxidation (PEO) process in suspension containing sodium phosphate and alumina nanopowder with environmentally friendly penicillin G benzathine inhibitor. This process was conducted by direct current and at constant current density. Effect of penicillin concentration on coating growth, absorption of alumina nanoparticles (suspended in the electrolyte), morphology, corrosion behavior of coating by energy dispersive X-ray spectroscopy, scanning electron microscopy and cyclic potentiodynamic polarization test was investigated. The results revealed that breakdown voltage in the presence of penicillin is increased up to 8%. The percentage of porosity in coating surface increased to 40% with increasing concentrations of penicillin. Thickness of coating in electrolytic containing penicillin has been halved. Concentration of 1.5 gr/Lit penicillin as an optimum concentration leads to improve the corrosion behavior of these samples relative to treated samples with no additives.