Effect of P-Phenylediamine on the Corrosion of Austenitic Stainless Steel Type 304 in Hydrochloric Acid

The effect of P-Phenylediamine on the corrosion behaviour of 304 stainless steel in 3M Hydrochloric acid solution contaminated with 3.5% sodium chloride was investigated using weight loss and potentiostatic polarization techniques. Corrosion parameters such as anodic and cathodic Tafel slope constants, corrosion potential, corrosion current, corrosion current densities, surface coverage and inhibition efficiency were calculated. The polarization measurements indicated that the inhibitors are of mixed type and inhibit corrosion by adsorption on the surface of steel due to the presence of more than one active centre in the inhibitor molecule. The inhibition effect ranged from 38.1% to 81.9% maximum at a concentration of between 0.125% to 1% before dropping sharply to between 9% and 4% at 1.25% to 1.5% concentration. The adsorption obeyed Langmuir adsorption isotherm up to 1% inhibitor concentration

Effect of Aminobenzene Concentrations on the Corrosion Inhibition of Mild Steel in Sulphuric Acid

The inhibiting action of aminobenzene concentration against the corrosion of mild steel in dilute sulphuric acid contaminated with 5% sodium chloride was studied using weight-loss method, calculated corrosion rates from the obtained weight loss data, potentiodynamic polarization measurements and metallographic macrographs. Results show aminobenzene has strong inhibitory effects with inhibitor efficiency increasing with increase in inhibitor concentration at ambient temperature. Maximum efficiency of 99.83% was obtained at 20% concentration of aminobenzene due to adhesion of the inhibitive precipitates through physisorption on the mild steel. This is further justified by the graphs of weight- loss and corrosion rate against exposure which illustrates the corrosion inhibition performance of the inhibitor. Results obtained from potentiodynamic experiments had good correlation with those of the gravimetric methods. The obtained macrographs could also be correlated with the gravimetric method dat

Effects of Nicotiana tobaccum extract additive on the quality of electroplating of zinc on mild steel.

Experimental investigations have been performed to determine the effects of nicotiana tobaccum (tobacco) extract additive on the electrodeposition of zinc on mild steel in acid chloride solution. The experiments were performed under different plating time, different additive concentrations and fi xed pH conditions. Zinc electrodeposition on mild steel was performed using a DC – supply at defi ned operating parameters. The surface of the plated steel was examined using scanning electron microscopy (SEM); and Energy Dispersive Spectroscopy (EDS) for the surface elemental composition analysis. Different surface characteristics were obtained depending upon the concentration of the additive and the plating time. The corrosion resistance of the plated surface was also determined by a gravimetric method. The quality of the electro-deposition of zinc was good as indicated by the microstructural morphology of the plated surface except for the few porosities observed. The electrodeposition process was sensitive to the changes in the additive concentration and plating time. Any variation in the plating parameter produced an entirely new and different surface morphology

Effect of cassava flour and coal dust additions on the mechanical properties of a synthetic moulding and sand

Loto, C.A., 1990. Effect of cassava flour and coal dust additions on the mechanical properties of a synthetic moulding sand. Appl. Clay Sci., 5: 249-263. An investigation has been made into the effects of cassava flour and coal dust additions on the mechanical properties of a newly developed synthetic moulding sand made from lgbokoda clay and \ silica sand. The results showed overall improved mechanical properties for both the cassava flour and coal dust additions though with a slight tolerable decrease in toughness. The improved mechanical properties, which resulted from the effective bonding property of cassava flour (starch) and fine · bituminous coal particles, were obtained when a certain optimum level of each of the additives were .! u sed with the optimum percent clay and tempering water

Electrode Potential Evaluation of Effect of Inhibitors on the Electrochemical Corrosion Behaviour of Mild Steel Reinforcement in Concrete in H2SO4

The electrochemical corrosion behaviour of mild steel embedded in concrete, and partially immersed in 0.2M H2SO4, was studied in this investigation at ambient temperature by potential monitoring technique. The experimental work was performed with a digital multimeter and a Cu/CuSO4 electrode (CSE) as the reference electrode. Extracts of carica papaya leaves and sodium nitrite (NaNO2) in different concentrations were separately and in combination, used as inhibitors. This paper reports the observed electrochemical response from the electrode potential monitoring of the embedded steel rebar during the experiments. The results obtained, showed a reduction in the active corrosion reactions behaviour of the embedded mild steel in concrete with added different concentrations of sodium nitrite and the pawpaw leaves extracts in the acidic test environment. This reduced active corrosion reaction was an indication of corrosion inhibition / protection characteristic. The observed inhibition was associated with the protective film provided on the embedded steel’s surface in the concrete by the complex chemical compounds of the plant leaves’ extracts and of the sodium nitrite with the alkaline composition/environment of the concrete constituents. The protective film prevented and/or reduced the chloride ions penetration to the steel surface. The combination of c. papaya extracts and the NaNO2 solution also provided effective corrosion inhibition of the embedded steel by synergism. The 100% concentration of each of the inhibitors and when in combinations, exhibited the most effective corrosion inhibition performance in the sulphuric acid test environment