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The achievement of high corrosion inhibition performances by manipulating the molecular structure of organic substances has gained much attention in recent years. In this paper, POCl3 was synthesized and Cl atoms in phosphoryl chloride (POCl3) were replaced by aniline or phenyl hydrazine and their derivatives; the effect of the substitution on the corrosion inhibition performance for mild steel immersed in 1 M HCl solution was investigated. Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR) and ultraviolet-visible (UV–Vis) spectroscopy were used to determine the molecular structure of the synthesized organic substances. Electrochemical impedance spectroscopy (EIS) and polarization measurements were employed to investigate the corrosion inhibition performance of the organic molecules for the immersed mild steel samples in the acid solution. The obtained results indicated that the inhibition efficiency of the synthesized inhibitors was increased by increasing the molecular size of the organic substances as well as increasing the number of nitrogen and oxygen heteroatoms in the structure of the organic molecules. The maximum amount of inhibition efficiency of the synthesized organic inhibitors in this paper was obtained about 93%.

Nowadays, powder coating can be used for many application, especially for protection against corrosive environments. Powder coating is usually done with using an electrostatic device and spraying gun. With using this method, a thin film layer is created on the surface which can play decorative or protective role. In this paper, the effect of some factors such as size of powder, charging, voltage, air flow, gun distance, charge–to-mass ratio, feed rate, coating functionality, glass transition temperature (Tg), viscosity, catalyst, temperature and curing time on the coating properties and their influence on the coating were mentioned. In recent years, nano composite polymers have been considered severely. Coating properties are improved by adding nanoparticles such as clay, SiO2, TiO2 and Al2O3 to the polymer composition. These coatings are used for reducing the gas permeability, thermal stability, optical clarity and increasing the mechanical and corrosion properties of coatings also these coatings have high mechanical properties that can be pointed to its high abrasion resistance. In this paper, the corrosion properties and the effect of adding nanoparticles on the corrosion resistance properties of powder coatings have been investigated, also the mechanical properties of powder coatings were reviwed.

This paper investigates the effect of yttria (Y2O3) coating on high temperature oxidation behaviour of low alloy 9 Cr–1Mo steel. The superficial coating is Y2O3 was prepared for experimental investigation. The isothermal corrosion study of uncoated and coated specimens was carried out in air oxidation environment at 973 K for 8 h. The corrosion rate and reaction kinetics were studied and the post corroded scales were characterized in SEM, EDS and XRD. The results clearly indicate that Y2O3 coated specimen improves the high temperature oxidation resistance than uncoated specimens. The improvement of oxidation resistance in presence of Y2O3 coating can be attributed to the changed mechanism of scale growth from outer cation migration to inner anion migration and enhancement of scale adhesion with the substrate. Further, enhancement of scale adhesion with the substrate in case of Y2O3 coating also improves the oxidation resistance. The detail mechanism of the oxidation of Y2O3 coated and uncoated specimen is further discussed in this paper.

The influence of superficial CeO2 coatings on isothermal and cyclic high temperature corrosion behavior of 2.25 Cr-1 Mo steel in oxidation and sulfidation (SO2 + O2) atmosphere have been reported in this paper. The CeO2 coating of three different depositions rate (0.15 mg/cm2, 0.30 mg/cm2 and 0.50 mg/cm2) were prepared for experimental investigations. The isothermal corrosion study of uncoated and CeO2 coated specimens was carried out in SO2 + O2 environment at 973K for 150 hours. The results clearly indicate that CeO2 coated specimen improves the high temperature corrosion resistance than uncoated specimens. The post corroded CeO2 coated specimen shows reduction of scale growth and improved scale adhesion to the substrate. The cyclic corrosion study was also carried out in both coated and uncoated specimen in same environment at 973K for 100 h. The CeO2 coated specimens on thermal cycling also shows significant improvement of the corrosion resistance without scale cracking and spallations. In contrary, the uncoated specimen in both isothermal as well as cyclic environment shows higher corrosion rate along with scale cracking and spallations. The results of the reaction kinetics have been substantiated by post corrosion analysis of alloy/scales combinations by SEM and XRD. The details mechanism of the corrosion in presence of CeO2 coating was further discussed in the paper.