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S. Hejazi,Sh. Mohajernia,M.H. Moayed,A. Davoodi,M. Rahimizadeh,M. Momeni,A. Eslami,A. Shiri,A. Kosari 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.25 No.-
Inhibitive performance of a new thiazolo-pyrimidine derivative has been investigated on mild steel in a solution of 1 M H2SO4. Electrochemical measurement, scanning electron microscope analysis and quantum chemical calculations are the tests and methods used to assess the performance of the inhibitors. The results indicate that the thiazolo-pyrimidine derivative used acts as a mixed-type inhibitor retarding the anodic and cathodic corrosion reactions. The studied compounds followed the Langmuir adsorption isotherm. Thermodynamic parameters showed that inhibitor adsorption is physical as determined by those parameters. The effect of molecular structure on the inhibition efficiency was investigated by quantum chemical calculations.
A. Davoodi,M. Babaiee,M. Pakshir 대한금속·재료학회 2013 METALS AND MATERIALS International Vol.19 No.4
Temperature fluctuations are inevitable in sour oil and gas production. In this study, the H2S corrosion of 304L and 316L alloys was investigated at pH 3 and temperatures of 20-60 °C using DC and AC electrochemical techniques. Two-fold increases in the corrosion rates of both alloys were reported with increases in temperature to 60 °C. In the 304L alloy, the surface layer was observed to be 3% rougher and 34%thicker than that of the 316L alloy. The two alloys exhibited different corrosion behaviors in the temperature ranges of 20-40 °C and 40-60 °C. Although the 316L alloy revealed a greater corrosion resistance at the free potential condition, the passivation on the 304L alloy was significantly greater than that of the 316L alloy at 40 °C and 15 ppm H2S. The FeS2 and combined FeS2-MoS2 compounds contributed to the surface layer constituents in the 304L and 316L alloys, respectively. The increase in temperature kinetically provided more favorable conditions for FeS2 than MoS2 formation, i.e. it had a relatively constructive effect on the 304L alloy passivation.
M. R. Davoodi,A. Golabi,H. A. Talebi,H. R. Momeni 제어로봇시스템학회 2011 제어로봇시스템학회 국제학술대회 논문집 Vol.2011 No.10
This paper addresses the problem of mixed H_ /H∞ fault detection observer design for discrete-time switched linear systems. The conventional mixed H_ /H∞ problem is a conservative approach due to the selection of equal Lyapunov matrices. The idea presented in this paper is based on a switched Lyapunov function and using conservatism reduction approaches which leads to some sufficient conditions for solvability of the problem in terms of linear matrix inequality (LMI) feasibility conditions. Numerical simulations are presented to show the effectiveness of the proposed approach.
E. Naderi,A. Davoodi,H. R. Jafarian 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.11
Corrosion of WE43 magnesium alloys after equal-channel angular pressing (ECAP) process with one pass (1P), two pass(2P), three pass (3P) and four pass (4P) were investigated as a function of immersion time in 37 ± 2 °C simulated body fluid(SBF) to imitate body corrosion environment utilizing AC electrochemical impedance spectroscopy (EIS), Potentiodynamicpolarization (PDP) curves, SEM and optical microscopy techniques in addition to EDS analysis. Among the samples, 2P and3P samples illustrated better corrosion resistance not only among all the samples but also as a function of elapsed immersiontime in SBF media. Better corrosion resistance was related to precipitation of β particles with fair and large volume fractionwhich served as cathodic reaction sites. Uniform distribution of the reactions not only reduce the severity of micro-galvaniccorrosion but also by passing immersion time, anodic reaction dissolved magnesium substrate next to and around β phaseand separate them from the surface which resulted loss of cathodic sites and reduction of corrosion. Additionally, the morphologyof the β phase was changed from needle-like in 1P & 2P samples to spherical one in 3P & 4P samples. It is believeddiminished corrosion resistance of 4P samples not only among the ECAPed samples but also as a function of immersiontime, were related to coarsening of spherical β phase. In another word, corrosion reactions amplified and continued whileseparation of the phase from the surface was delayed due to its larger size.