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This paper aims to investigate the influence of temperature (25-65°C) on the adsorption and the inhibition efficiency of gum arabic (GA) for the corrosion of API 5L X42 pipeline steel in 1M HCl.

Inhibition behaviour on steel in HCl has been studied in relation to the concentration of the inhibitor and the temperature using potentiodynamic polarization curves and electrochemical impedance spectroscopy. Thermodynamic parameters of adsorption were calculated from the viewpoint of adsorption theory.

The results show that at a temperature range from 25 to 65°C, GA was a good inhibitor for API 5L X42 pipeline steel, and its inhibition efficiency was significantly stable. The maximum inhibition efficiency (93 per cent) is obtained at 4 g L⁻¹. In absence and presence of GA, there is almost no change in the corrosion mechanism regardless of the temperature. The adsorption of GA on steel surface is an exothermic process. The adsorption of GA involves physical adsorption.

The use of GA as an eco-friendly corrosion inhibitor is practical for carbon steel in HCl.

The stability of inhibition efficiency of GA at a temperature range from 25 to 65°C could find possible applications in acid pickling, industrial acid cleaning and acid descaling.

Because of its wide applications in the industry, the electrodeposition of Ni/Mo as corrosion barrier and decorative coating took the attention of numerous researchers. This paper aims to study the effect of electroplating current density on different characteristics of Ni/Mo alloy coatings, especially on the morphology and electrochemical comportment in 3.5 per cent NaCl corrosion medium.

In this paper, the authors have used electrodeposition technique to codeposite molybdenum particles in nickel matrix as protective coating against corrosion attacks, in addition to test the intensification of hydrogen reaction of this alloy coatings using EIS technique.

Ni-Mo alloy coating is well adherent to the substrate. The deposited Ni-Mo was observed to be fissured and porous in morphology. The main phases identified in different exposed coatings are MoNi4, Ni3Mo and Mo1.24Ni0.76. The effect of applied current density on electrochemical properties was studied. Inhibitory efficiency of gum arabic was controlled by the electroplating current density.

In this paper, the authors report on the presence of Mo particles in Ni matrix also the effect of electroplating current density on different properties of alloy coatings Ni/Mo. This is significant because it reports on the effect of current density on Ni/Mo electrodeposited at economic conditions like low temperature and moderate pH. Moreover, this paper gives a solution to the corrosion of crude oil desalter by using Ni-Mo coatings and then injecting a small amount of gum arabic in the oil pipeline before dissalement which gives long life to the reactor.