Olugbenga Adeshola Omotosho

Effect of NaNO2 and C6H15NO3 Synergistic Admixtures on Steel-Rebar Corrosion in Concrete Immersed in Aggressive Environments

This paper studies effect of different combinations of NaNO2 (sodium nitrite) and C6H15NO3 (triethanolamine (TEA)), as synergistic admixtures in concrete immersed in NaCl and in H2SO4 test environments, on the corrosion of the concrete reinforcing steel (rebar). Although statistically analysed electrochemical test results confirmed NaNO2 effectiveness, synergistic combinations of 4 g NaNO2

Phyllanthus muellerianus and C6H15NO3 synergistic effects on 0.5 M H2SO4-immersed steel-reinforced concrete: Implication for clean corrosion-protection of wind energy structures in industrial environment

This paper investigates Phyllanthus muellerianus leaf-extract and C6H15NO3 (triethanolamine: TEA) synergistic effects on reinforcing-steel corrosion-inhibition and the compressive-strength of steel-reinforced concrete immersed in 0.5 M H2SO4. This is to assess suitability of the synergistic admixture usage for wind-energy steel-reinforced concrete structures designed for industrial environments. Steel-reinforced concrete specimens were admixed with individual and synergistic designs of Phyllanthus muellerianus leaf-extract and C6H15NO3 admixtures and immersed in the 0.5 M H2SO4. Electrochemical monitoring of corrosion potential, as per ASTM C876-91 R99, and corrosion current were obtained and statistically analysed, as per ASTM G16-95 R04, for modelling noise resistance. Post-immersion compressive-strength testing then followed, as per ASTM C39/C39M–03, for detailing the admixture effect on load-bearing strength of the steel-reinforced concrete specimens. Results showed that while individual Phyllanthus muellerianus leaf-extract concentrations exhibited better inhibition-efficiency performance than C6H15NO3, synergistic additions of C6H15NO3 to Phyllanthus muellerianus leaf-extract improved steel-rebar corrosion-inhibition. Thus, 6 g Phyllanthus muellerianus + 2 g C6H15NO3 synergistically improved inhibition-efficiency to η = 84.17%, from η = 55.28% by the optimal chemical or from η = 74.72% by the optimal plant-extract admixtures. The study also established that improved compressive strength of steel-reinforced concrete with acceptable inhibition of the steel-rebar corrosion could be attained through optimal combination of the Phyllanthus muellerianus leaf-extract and C6H15NO3 admixtures.

Finite Element Modelling of Electrokinetic Deposition of Zinc on Mild Steel with ZnO-Citrus sinensis as Nano-Additive

The electrokinetic deposition of zinc on mild steel substrate under the influence of ZnO-Citrus sinensis nano-additive was investigated numerically using a Finite Element (FE) solver. The conductivity of the Acid chloride plus ZnO-Citrus sinensis nano-additive electrolyte and the properties of Zinc and mild steel electrodes were used as the input codes for the model. The model was designed on a 3-dimensional scale. The boundary conditions were set and the model was meshed using the finer mesh capability in the FE solver. The model was processed and readings of the modelled zinc deposited mild steel were taken, validated and analysed so as to get the optimum parameters from the deposition process. Based on the results, the deposition mass and thickness increased with deposition time with ZnO-Citrus sinensis nano-additive, it is thus recommended that relatively high deposition time should be used in order to achieve optimum deposition.

Cassia fistula Leaf-Extract Effect on Corrosion-Inhibition of Stainless-Steel in 0.5 M HCl

This paper investigates Cassia fistula leaf-extract effects on the inhibition of stainless-steel corrosion in 0.5 M HCl. Measurements of corrosion rate were obtained through linear sweep voltammetry (LSV) technique, at the ambient temperature of 28 °C from stainless-steel specimens immersed in the acidic medium, containing different Cassia fistula leaf-extract concentrations. Results showed that inhibition effectiveness on stainless-steel corrosion increases with increasing concentration of the leaf-extract. The 10 g/L Cassia fistula leaf-extract, the highest concentration of the leaf-extract employed in the study, exhibited optimal inhibition efficiency η = 88.46% on the corrosion of the stainless-steel metal. Adsorption isotherm modelling shows that the experimental data followed the Flory-Huggins isotherm with excellent model efficiency, r 2 = 90.27%, and the Langmuir model with very good model efficiency, r 2 = 78.83%. Other isotherm parameters indicate favourable adsorption and suggest physisorption as the prevalent mechanism of corrosion protection by the leaf-extract on stainless-steel in the acidic chloride environment.

Performance of Terminalia catappa on mild steel corrosion in HCl medium

This work investigates Terminalia catappa leaf-extract performance on mild steel corrosion in 0.5 M hydrochloric acid (HCl). Electrochemical linear-sweep-voltametry (LSV) and gravimetric techniques were employed for assessing the mild steel corrosion in the HCl test-environment of immersion having different concentrations of the leaf-extract. Results showed that all the concentrations of the Terminalia catappa leaf-extract employed inhibited mild steel corrosion from the electrochemical (potentiodynamic) and the gravimetric considerations. Also, corrosion rate from LSV exhibited excellent correlation (R = 95.77%, Nash-Sutcliffe Efficiency (NSE) = 91.72% and p-value = 0.02383) with linear function of the corrosion rate from gravimetric method, for the leaf-extract concentrations employed. From the experimental model, 6 g/L Terminalia catappa exhibited optimal inhibition efficiency, η = 78.07%, while 8 g/L Terminalia catappa was predicted as optimally effective, η = 75.41%, by the correlation fitting model, at inhibiting mild steel corrosion in the medium. However, adsorption isotherm modelling showed that the experimental gravimetric, experimental potentiodynamic and predicted potentiodynamic data exhibited agreements in following the Langmuir adsorption isotherm. All the three data models indicated favourable adsorption and identified physisorption as the prevalent adsorption mechanism of Terminalia catappa leaf-extract on mild steel immersed in the 0.5 M HCl medium.

Inhibition and mechanism of Terminalia catappa on mild-steel corrosion in sulphuric-acid environment

Mild-steel samples were immersed in 0.5 M H2SO4 having different concentrations of Terminalia catappa leaf-extract for investigating inhibition and mechanism of the leaf-extract on mild-steel corrosion in the test-environment. Corrosion-rate measurements were obtained by potentiodynamic polarisation and gravimetric techniques and analysed for detailing sustainable corrosion-protection by the natural-plant in the test-environment. Results indicate potentiodynamic corrosion-rate correlated excellently (R = 99.25%, Nash-Sutcliffe efficiency (NSE) = 98.52%, ANOVA p-value = 0.0222) with function of the gravimetric corrosion-rate and the leaf-extract concentration. By the experimental and correlated results, inhibition effectiveness on mild-steel corrosion increased with increasing leaf-extract concentration up to the 8 g/L Terminalia catappa leaf-extract, which exhibited optimal inhibition efficiency, η = 99.99% (experimental model) or η = 95.45% (correlation prediction). Correlation prediction, potentiodynamic and gravimetric data followed the Langmuir and the Flory-Huggins adsorption isotherms with agreements of favourable adsorption/prevalent physisorption mechanism for the leaf-extract corrosion-protection of mild-steel in the test-environment.

Anticorrosion Performance of Solanum Aethiopicum on Steel-Reinforcement in Concrete Immersed in Industrial/Microbial Simulating-Environment

This paper investigates anticorrosion performance of Solanum aethiopicum leaf-extract on steel-reinforcement in concrete immersed in 0.5 M H2SO4, simulating industrial/microbial environment. For this, corrosion rate by linear polarisation resistance and corrosion potential as per ASTM C876-91 R99 were monitored from steel-reinforced concrete slabs admix ed with different Solanum aethiopicum leaf-extract concentrations and immersed in the acidic test-environment. Obtained test-data were subjected to statistical probability distributions for which compatibilities were tested using Kolmogorov-Smirnov goodness-of-fit statistics, as per ASTM G16-95 R04. These identified all datasets of corrosion test-data, from the steel-reinforced concrete samples, as coming from the Weibull probability distribution. Analysed results showed that Solanum aethiopicum leaf-extract reduced rebar corrosion condition from “high” to “low” corrosion risks of ASTM C876-91 R99. Also, the corrosion rate analyses identified 0.25% Solanum aethiopicum leaf-extract with optimal inhibition efficiency performance, η = 93.99%, while the other concentrations also exhibited good inhibition of steel-reinforcement corrosion in the test-environment.

Inhibition of Stainless Steel Corrosion IN 0.5 M H2SO4 IN The Presence OF C6H5NH2

Inhibition of stainless steel corrosion in 0.5 M H2SO4 by C6H5NH2 (Aniline) at different temperatures was experimentally studied in this paper. Corrosion rate measurements at 28°C, 45°C and 60°C were taken through linear sweep voltametry and utilised for modelling inhibition efficiency and thermodynamic properties in the acidic solution containing different concentrations of the organic chemical. Results showed that inhibition of stainless steel in 0.5 M H2SO4 increased with increasing temperature for most of the different concentrations of C6H5NH2 employed. Optimal inhibition efficiency ranged from η = 26.49% by 0.043 M C6H5NH2 at 28°C, through η = 88.99% by 0.021 M C6H5NH2 at 45°C up to η = 96.68% by 0.043 M C6H5NH2 at 60°C. Also, thermodynamic property analyses showed that apparent activating energy decreases from the uninhibited, 0 M C6H5NH2, to the optimally inhibiting 0.043 M C6H5NH2 containing medium, which suggests C6H5NH2 adsorption drives the inhibition effects observed.

Impact of Heat Treatment on HSS Cutting Tool (ASTM A600) and Its Behaviour during Machining Of Mild Steel(ASTM A36)

Carburization is one the best heat treatment that responded well to hardening with Palm Kernel Shell giving the best hardness value. This work studied the influence of carburization on HSStool(ASTM A600) and its behaviour during machining of mild steel (ASTM A36). Composition of the samples (12 pieces of 180 x 12 x12 mm) HSS tools were checked using UV-VIS spectrometer and the tools were carburized with PKS at holding temperatures and time of 800, 850, 900,950 oC and 60,90 120 minutes using muffle furnance. The micro structural analysis, surface and core hardnessof the treated samples gave better results than the untreated samples when checked withsoft driven and optical microscope. It wasalso observed that increase in the feed rate and depth for length of cut of 50 mm significantly reduces the wear progression and thereby gave best machining time at maximum carburizing temperature and time(950 oC / 120 minutes) when it was used to cut mild steelon the lathe machine.

Investigating inhibition of microbes inducing microbiologically-influenced-corrosion by Tectona grandis based Fe-nanoparticle material

In this paper, inhibition of microbes inducing microbiologically-influenced-corrosion (MIC) of metals by Tectona grandis based Fe (iron) Nanoparticle material was investigated. For this, extract was obtained from the leaf of Tectona grandis and this was employed as precursor for synthesizing the Fe-nanoparticle material. From this, the synthesized plant extract based nanoparticle material was characterized using scanning electron microscopy and energy dispersive spectroscopy (SEM+EDS) instrument. The developed Fe bio-nanoparticle material was then employed for sensitivity and/or resistance study application against different strains of microbes that are known to induce microbiologically-influenced-corrosion, in metallic materials, and for this, microbial growth inhibition effect was compared with that from a commercial antibiotic employed as control. Results showed that the Tectona grandis based Fe-nanoparticle exhibited good inhibition effects on the growth of many of the MIC inducing microbes investigated. Sensitivity measures of zone of inhibition against the growth of MIC inducing microbial strains either outperformed or compares well with that obtained from the commercial antibiotic control, in the study. These results indicate positive prospect on the suitability of Fe bio-nanoparticle for corrosion inhibition applications for the protection of metals against microbiological corrosion influencing environment.