Loading...
Search for:
peo
0.005 seconds
Effect of current frequency on coating properties formed on aluminised steel by plasma electrolytic oxidation
, Article Surface Engineering ; Vol. 30, issue. 3 , 2014 , pp. 224-228 ; ISSN: 02670844 ; Faghihi Sani, M. A ; Rafizadeh, E ; Sharif University of Technology
Abstract
In the present study, plasma electrolytic oxidation process was carried out on aluminised steel with a pulsed bipolar electrical source at different frequencies, namely, 50, 300, 600 and 1500 Hz with constant 50% duty cycle for 10 min in an alkaline silicate electrolyte. Morphology, wear behaviour and corrosion resistance of the coatings were investigated by scanning electron microscopy, pin on disc and potentiodynamic polarisation experiment in 3·5 wt-%NaCl solution. The results showed that with increasing the pulse frequency, the density of the residual pores increases, but their size as well as the coating thickness decreases. The corrosion current density of the coating processed at 1500...
plasma Electrolytic Oxidation of AZ31 in Silicate and Phosphate Electrolyte and Study of Corrosion Behavior
, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad (Supervisor)
Abstract
In recent years, magnesium and its alloys have been considered as biodegradable implants, but they corrode in the body before natural process of damaged organs recovery is completed. In this investigation PEO operation was used for corrosion control and effect of different parameter such as number of operation steps, electrolyte type, time and operation voltage on coating properties was studied. Scanning electron microscopy was used for investigating of morphology of coats and to determine chemical composition and phase of coats EDS analysis and X-ray diffraction were used. The corrosion resistance of samples were evaluated by potentiodynamic polarization and electrochemical impedance (EIS)...
Formation of Two-Step Plasma Electrolytic Oxidation Coating On Commercially Pure Titanium and Study its Properties
, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad (Supervisor)
Abstract
Improvement of biological properties by modifying the composition and morphology of the surface layer is one of the main goals of using plasma electrolytic oxidation (PEO) for coating titanium implants. The purpose of this research is formation of biocompatible coating containing calcium, phosphorus and silicon on titanium by two-step PEO method in DC, constant voltage mode. In addition to good corrosion properties of the resultant coatings in simulated body environment (SBF), Having good adhesion due to the use of electrolytes with useful elements for biological function in both step of coating process rather than acidic electrolytes which are incompatible with the body environment, this...
Crystallization of hydroxyapatite during hydrothermal treatment on amorphous calcium phosphate layer coated by PEO technique
, Article Ceramics International ; Volume 39, Issue 2 , 2013 , Pages 1793-1798 ; 02728842 (ISSN) ; Arbabi, A ; Mehdinezhad Roshan, A ; Sharif University of Technology
2013
Abstract
Surface modification of titanium implants is recently considered by several researchers. In this study, PEO was performed over commercially Ti-6Al-4V alloy pellets in an aqueous electrolyte containing calcium acetate (C.A.) and calcium glycerphosphate (Ca-GP) with a Ca/P molar ratio of 6.8, and applying current density of 0.212 A/cm2, frequency of 100 Hz and duty ratio of 60% for 4 min. In the next step, hydrothermal treatments were carried out for various durations and at different temperatures inside an autoclave chamber containing a NaOH solution with pH of 11.5. XRD and SEM results confirmed formation of needle-shaped HAp after all hydrothermal conditions. Maximum intensity of HAp peaks...
Improved electrochemical performance of plasma electrolytic oxidation coating on titanium in simulated body fluid
, Article Journal of Materials Engineering and Performance ; Volume 28, Issue 7 , 2019 , Pages 4120-4127 ; 10599495 (ISSN) ; Aliasghari, S ; Ghorbani, M ; Sharif University of Technology
Springer New York LLC
2019
Abstract
The effect of plasma electrolytic oxidation (PEO) pre-treatments on corrosion behavior of titanium in simulated body fluid (SBF) is investigated. Three pre-treatments are compared, using silicate, calcium phosphate and mixed silicate and calcium phosphate (1:1) electrolytes, respectively. The resultant coatings in different compositions and morphologies were examined by high-resolution field emission scanning electron microscopy equipped with energy-dispersive spectrometer and x-ray diffraction. The PEO-treated specimens revealed distribution of coating species, mainly the titanium-rich inner coating region. However, findings show highly localized variations in composition within their...