The electrochemical behavior of single-layer TiN, CrN, CrAlN, and TiAlN coatings on 304 stainless... more The electrochemical behavior of single-layer TiN, CrN, CrAlN, and TiAlN coatings on 304 stainless steel substrate, deposited using state-of-the-art and industrial size cathodic arc PVD machine, were evaluated in 1M HCl and 3.5 pct NaCl solutions. The corrosion behavior of the blank and coated substrates was analyzed by electrochemical impedance spectroscopy (EIS), linear polarization resistance, and potentiodynamic polarization. Bond-coat layers of pure-Ti, pure-Cr, alloyed-CrAl, and alloyed-TiAl for TiN, CrN, CrAlN, and TiAlN coatings were, respectively, first deposited for improved coating adhesion before the actual coating. The average coating thickness was about 1.80 µm. Results showed that the corrosion potentials (Ecorr) of the coated substrates were shifted to more noble values which indicated improvement of the coated substrate resistance to corrosion susceptibility. The corrosion current densities were lower for all coated substrates as compared to the blank substrate. Similarly, EIS parameters showed that these coatings possessed improved resistance to defects and pores in similar solution compared to the same nitride coatings developed by magnetron sputtering. The charge transfer resistance (Rct) can be ranked in the following order: TiAlN > CrN > TiN > CrAlN in both media except in NaCl solution where Rct of TiN is lowest. While the pore resistance (Rpo) followed the order: CrAlN > CrN > TiAlN > TiN in HCl solution and TiAlN > CrN > CrAlN > TiN in NaCl solution. It is found that TiAlN coating has the highest protective efficiencies of 79 and 99 pct in 1M HCl and 3.5 pct NaCl, respectively. SEM analysis of the corroded substrates in both media was also presented.
The corrosion inhibition effect of pectin (a biopolymer) for X60 pipeline steel in HCl medium was... more The corrosion inhibition effect of pectin (a biopolymer) for X60 pipeline steel in HCl medium was investigated using weight loss, electrochemical, water contact angle measurements, and scanning electron microscopy techniques. The results obtained show that pectin acts as a good corrosion inhibitor for X60 steel. Inhibition efficiency increased with increase in pectin concentration and temperature. Potentiodynamic polarization results reveal that pectin could be classified as a mixed-type corrosion inhibitor with predominant control of the cathodic reaction. The effective corrosion inhibition potential of pectin could be related to the adsorption of pectin molecules at the metal/solution interface which is found to accord with the Langmuir adsorption isotherm model and a protective film formation. Quantum chemical calculations provided insights into the active sites and reactivity parameters governing pectin activity as a good corrosion inhibitor for X60 steel.
... 331-337.1479 Effect of Temper on Environmental Fatigue Crack Propagation in 7000-Series Alumi... more ... 331-337.1479 Effect of Temper on Environmental Fatigue Crack Propagation in 7000-Series Aluminum Alloys Zuhair M. Gasem and Richard P. Gangloff Department of Materials Science and Engineering ... 15. M. Khobaib, CT Lynch and FW Vahldiek, Corros., 36 (1981), p. 285. ...
ABSTRACT The use of computational chemistry as a tool in the design and development of organic co... more ABSTRACT The use of computational chemistry as a tool in the design and development of organic corrosion inhibitors has been greatly enhanced by the development of density functional theory (DFT). Whereas, traditionally, corrosion scientists have identified new corrosion inhibitor molecules either by incrementally changing the structures of existing inhibitors or by testing hundreds of compounds in the laboratory, these experimental means are often very expensive and time-consuming. Thus, ongoing hardware and software advances have opened the door for powerful use of theoretical chemistry in corrosion inhibition research at a reduced cost. DFT has enabled corrosion scientist to accurately predict the inhibition efficacies of organic corrosion inhibitors based on electronic/molecular properties and reactivity indices. This review summarizes the main features of DFT, giving a brief background to selected DFT-based chemical reactivity concepts, calculations and their applications to organic corrosion inhibitor design. The paper also reviews the principles upon which modern corrosion science is based with emphasis on corrosion in the oil and gas industry and with the goal of identifying important issues in the design of new, more effective inhibitors in this field. The impact of this review is to illustrate the enormous power of DFT and to identify shortcomings in past work, including the assumption that inhibitors only interact with bare metal surfaces.
ABSTRACT The adsorption and corrosion inhibition behavior of strawberry fruit extract at steel/1 ... more ABSTRACT The adsorption and corrosion inhibition behavior of strawberry fruit extract at steel/1 M HCl and steel/0.5 M H2SO4 interfaces were investigated using gravimetric and electrochemical methods at 25 and 60 °C. Results obtained showed that the extract inhibited the acid-induced corrosion of mild steel which was more pronounced in HCl than H2SO4 medium. Inhibition efficiency increased with increase in the concentration of the extract but decreased with increase in temperature. The potentiodynamic polarization studies revealed that the extract functions as mixed-type inhibitors. The inhibition was assumed to occur via adsorption of the components of the extract on the mild steel surface which can be approximated by Langmuir adsorption isotherm model. Quantum-chemical calculations and molecular dynamics simulations have been used to provide insights into the mechanism of interaction of ascorbic acid as a major constituent of the extract with mild steel.
Materials science & engineering. C, Materials for biological applications, 2014
The present investigation describes the versatile fabrication and characterization of a novel com... more The present investigation describes the versatile fabrication and characterization of a novel composite coating that consists of polypyrrole (PPy) and Nb2O5 nanoparticles. Integration of the two materials is achieved by electrochemical deposition on 316L stainless steel (SS) from an aqueous solution of oxalic acid containing pyrrole and Nb2O5 nanoparticles. Fourier transform infrared spectral (FTIR) and X-ray diffraction (XRD) studies revealed that the existence of Nb2O5 nanoparticles in PPy matrix with hexagonal structure. Surface morphological analysis showed that the presence of Nb2O5 nanoparticles strongly influenced the surface nature of the nanocomposite coated 316L SS. Micro hardness results revealed the enhanced mechanical properties of PPy nanocomposite coated 316L SS due to the addition of Nb2O5 nanoparticles. The electrochemical studies were carried out using cyclic polarization and electrochemical impedance spectroscopy (EIS) measurements. In order to evaluate the biocom...
Journal of Dispersion Science and Technology, 2014
ABSTRACT The corrosion inhibition effect of red apple (Malus domestica) fruit extract for mild st... more ABSTRACT The corrosion inhibition effect of red apple (Malus domestica) fruit extract for mild steel in hydrochloric acid was investigated by gravimetric and electrochemical methods at 30–60°C. Inhibition efficiency increased with the increase in concentration and temperature. Polarization curves indicate that the extract functions as mixed-type inhibitor. The adsorption of the extract onto mild steel surface followed Langmuir adsorption isotherm model. Chemisorption mechanism is proposed based on the trend of inhibition efficiency with temperature. Quantum chemical calculations and molecular dynamics simulations have been used to provide insights into the mechanism of interaction of the major extract components with mild steel.
The electrochemical behavior of single-layer TiN, CrN, CrAlN, and TiAlN coatings on 304 stainless... more The electrochemical behavior of single-layer TiN, CrN, CrAlN, and TiAlN coatings on 304 stainless steel substrate, deposited using state-of-the-art and industrial size cathodic arc PVD machine, were evaluated in 1M HCl and 3.5 pct NaCl solutions. The corrosion behavior of the blank and coated substrates was analyzed by electrochemical impedance spectroscopy (EIS), linear polarization resistance, and potentiodynamic polarization. Bond-coat layers of pure-Ti, pure-Cr, alloyed-CrAl, and alloyed-TiAl for TiN, CrN, CrAlN, and TiAlN coatings were, respectively, first deposited for improved coating adhesion before the actual coating. The average coating thickness was about 1.80 µm. Results showed that the corrosion potentials (Ecorr) of the coated substrates were shifted to more noble values which indicated improvement of the coated substrate resistance to corrosion susceptibility. The corrosion current densities were lower for all coated substrates as compared to the blank substrate. Similarly, EIS parameters showed that these coatings possessed improved resistance to defects and pores in similar solution compared to the same nitride coatings developed by magnetron sputtering. The charge transfer resistance (Rct) can be ranked in the following order: TiAlN > CrN > TiN > CrAlN in both media except in NaCl solution where Rct of TiN is lowest. While the pore resistance (Rpo) followed the order: CrAlN > CrN > TiAlN > TiN in HCl solution and TiAlN > CrN > CrAlN > TiN in NaCl solution. It is found that TiAlN coating has the highest protective efficiencies of 79 and 99 pct in 1M HCl and 3.5 pct NaCl, respectively. SEM analysis of the corroded substrates in both media was also presented.
The corrosion inhibition effect of pectin (a biopolymer) for X60 pipeline steel in HCl medium was... more The corrosion inhibition effect of pectin (a biopolymer) for X60 pipeline steel in HCl medium was investigated using weight loss, electrochemical, water contact angle measurements, and scanning electron microscopy techniques. The results obtained show that pectin acts as a good corrosion inhibitor for X60 steel. Inhibition efficiency increased with increase in pectin concentration and temperature. Potentiodynamic polarization results reveal that pectin could be classified as a mixed-type corrosion inhibitor with predominant control of the cathodic reaction. The effective corrosion inhibition potential of pectin could be related to the adsorption of pectin molecules at the metal/solution interface which is found to accord with the Langmuir adsorption isotherm model and a protective film formation. Quantum chemical calculations provided insights into the active sites and reactivity parameters governing pectin activity as a good corrosion inhibitor for X60 steel.
... 331-337.1479 Effect of Temper on Environmental Fatigue Crack Propagation in 7000-Series Alumi... more ... 331-337.1479 Effect of Temper on Environmental Fatigue Crack Propagation in 7000-Series Aluminum Alloys Zuhair M. Gasem and Richard P. Gangloff Department of Materials Science and Engineering ... 15. M. Khobaib, CT Lynch and FW Vahldiek, Corros., 36 (1981), p. 285. ...
ABSTRACT The use of computational chemistry as a tool in the design and development of organic co... more ABSTRACT The use of computational chemistry as a tool in the design and development of organic corrosion inhibitors has been greatly enhanced by the development of density functional theory (DFT). Whereas, traditionally, corrosion scientists have identified new corrosion inhibitor molecules either by incrementally changing the structures of existing inhibitors or by testing hundreds of compounds in the laboratory, these experimental means are often very expensive and time-consuming. Thus, ongoing hardware and software advances have opened the door for powerful use of theoretical chemistry in corrosion inhibition research at a reduced cost. DFT has enabled corrosion scientist to accurately predict the inhibition efficacies of organic corrosion inhibitors based on electronic/molecular properties and reactivity indices. This review summarizes the main features of DFT, giving a brief background to selected DFT-based chemical reactivity concepts, calculations and their applications to organic corrosion inhibitor design. The paper also reviews the principles upon which modern corrosion science is based with emphasis on corrosion in the oil and gas industry and with the goal of identifying important issues in the design of new, more effective inhibitors in this field. The impact of this review is to illustrate the enormous power of DFT and to identify shortcomings in past work, including the assumption that inhibitors only interact with bare metal surfaces.
ABSTRACT The adsorption and corrosion inhibition behavior of strawberry fruit extract at steel/1 ... more ABSTRACT The adsorption and corrosion inhibition behavior of strawberry fruit extract at steel/1 M HCl and steel/0.5 M H2SO4 interfaces were investigated using gravimetric and electrochemical methods at 25 and 60 °C. Results obtained showed that the extract inhibited the acid-induced corrosion of mild steel which was more pronounced in HCl than H2SO4 medium. Inhibition efficiency increased with increase in the concentration of the extract but decreased with increase in temperature. The potentiodynamic polarization studies revealed that the extract functions as mixed-type inhibitors. The inhibition was assumed to occur via adsorption of the components of the extract on the mild steel surface which can be approximated by Langmuir adsorption isotherm model. Quantum-chemical calculations and molecular dynamics simulations have been used to provide insights into the mechanism of interaction of ascorbic acid as a major constituent of the extract with mild steel.
Materials science & engineering. C, Materials for biological applications, 2014
The present investigation describes the versatile fabrication and characterization of a novel com... more The present investigation describes the versatile fabrication and characterization of a novel composite coating that consists of polypyrrole (PPy) and Nb2O5 nanoparticles. Integration of the two materials is achieved by electrochemical deposition on 316L stainless steel (SS) from an aqueous solution of oxalic acid containing pyrrole and Nb2O5 nanoparticles. Fourier transform infrared spectral (FTIR) and X-ray diffraction (XRD) studies revealed that the existence of Nb2O5 nanoparticles in PPy matrix with hexagonal structure. Surface morphological analysis showed that the presence of Nb2O5 nanoparticles strongly influenced the surface nature of the nanocomposite coated 316L SS. Micro hardness results revealed the enhanced mechanical properties of PPy nanocomposite coated 316L SS due to the addition of Nb2O5 nanoparticles. The electrochemical studies were carried out using cyclic polarization and electrochemical impedance spectroscopy (EIS) measurements. In order to evaluate the biocom...
Journal of Dispersion Science and Technology, 2014
ABSTRACT The corrosion inhibition effect of red apple (Malus domestica) fruit extract for mild st... more ABSTRACT The corrosion inhibition effect of red apple (Malus domestica) fruit extract for mild steel in hydrochloric acid was investigated by gravimetric and electrochemical methods at 30–60°C. Inhibition efficiency increased with the increase in concentration and temperature. Polarization curves indicate that the extract functions as mixed-type inhibitor. The adsorption of the extract onto mild steel surface followed Langmuir adsorption isotherm model. Chemisorption mechanism is proposed based on the trend of inhibition efficiency with temperature. Quantum chemical calculations and molecular dynamics simulations have been used to provide insights into the mechanism of interaction of the major extract components with mild steel.
Uploads
Papers