Rapid investigation expiry drug green corrosion inhibitor on mild steel in NaCl medium

The unused expired clinical drugs are a major environmental hazardous pollutant due to the pharmaceutically active organic compounds present in it. Until recently, a quantum of unused drugs is being disposed through sewers, drainage, sediment are a threat to the public health. Several researchers have already reported the potential use of expired drugs as corrosion inhibitors in both acidic and alkaline medium. In this paper, we have reported three different drug molecules which have crossed the expiry date but not beyond six months. The drugs considered are rabeprazolesodium, domperidone and benfotiamine. Mild steel (MS) specimens were immersed 5 days with and without drug molecule in 3.5 wt% medium film formed on MS surface. These films were then analysed for crystallinity, surface morphology, iron complex, DFT and functional groups by XRD, SEM, and 3D profilometer, FTIR, UV and EPR. The experimental and theoretical results are good agreement with each other

A study of martensitic stainless steel AISI 420 modified using plasma nitriding

We studied martensitic stainless steel AISI 420, modified using glow discharge plasma nitriding. Microhardness measurements, X-ray diffraction (XRD), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) were used to investigate the surface microhardness, crystal structure, microstructure and chemical bonding in the modified surfaces. High surface microhardness (~1300 HV) over a case depth of about 60 microns is obtained. Glancing incidence X-ray diffraction (GIXRD) indicates the presence of a predominantly Fe3N phase with dispersed CrN within 2-5 microns on the surface. In addition, using Bragg-Brentano geometry, we measured the presence of a minor phase of Fe4N in the case depth. SEM confirms that the microstructure within 2-5 microns of the surface is different from that of the bulk. XPS shows nitride phase formation on the surface. AES measured over the cross-section of the case depth shows a direct relation of the increased surface microhardness to the high nitrogen content

Plasma-source ion implantation compared with glow-discharge plasma nitriding of stainless steel

Plasma-source ion implantation (PSII) is a promising technology to overcome the line-of-sight limitations of beam-line ion implantation. Among the possible fields of commercial use, nitriding of stainless steels by plasma-source ion implantation seems to be one of the favourites. However, the technology of glow-discharge plasma nitriding (GDPN) is already being used commercially. Therefore, it remains to be determined whether PSII is more suitable to the demands of an industrial technology than GDPN. In particular, the incorporation rate of nitrogen during treatment has to be investigated, as the incorporation rate of nitrogen determines the depth of the nitrided layer for a given treatment time. For nitriding of stainless steel, PSII and GDPN were performed for the same treatment time of 2 h, using the same treatment voltage (700 V) and duty ratio (50%) during the nitriding process. The temperature during treatment was fixed at 380 °C and controlled by an isolated thermocouple. The only difference in the experimental conditions was the pressure, during treatment, of 0.1 Pa in the case of PSII and 500 Pa in the case of GDPN. Pure nitrogen as well as a nitrogen-hydrogen mixture was used as the feed gas. The resulting concentration profiles were determined by glow-discharge optical spectroscopy depth profiling to determine the nitrogen incorporation rate of both nitriding techniques. The surface properties were investigated by wear and hardness measurements. Both technologies yield the formation of a hard nitrided layer with an increased hardness. The highest nitrogen concentration and widest hardened layer was found in the case of PSII, using a nitrogen-hydrogen plasma

Corrosion resistance improvement of high carbon low alloy steel by plasma nitriding

The present study concerns improving the corrosion resistance of a low alloy-high carbon steel by plasma nitriding in pulsed direct current glow discharge mode at an applied voltage of 540-710 V with 3-6 A current in the temperature range 450-560°C for a time period of 1-5 h. The phases formed after nitriding is mostly γ'-Fe4N with a small volume fraction of ε-Fe3N/Fe2N. Nitride volume fraction increases with nitriding time and temperature. Corrosion study reveals that plasma nitriding significantly improves the corrosion resistance in terms of corrosion potential, corrosion current density and resistance to polarization. This improvement is attributed to both formation of solid solution and nitrides on the surface

Electronic structure, microstructure, and crystal structure of the precipitation-hardened alloy Cu<SUB>98</SUB>Be<SUB>1.8</SUB>Co<SUB>0.2</SUB>

Precipitation hardening of copper alloys results in improved elastic properties but is accompanied by reduction in electrical conductivity. We study the electronic structure, microstructure, and crystal structure of precipitation-hardened Cu:Be:Co (98:1.8:0.2 weight %) alloy to look for coupled changes accompanying the precipitation hardening. X-ray diffraction is used to study the strain in the Cu matrix upon Guinier-Preston zone formation and the subsequent precipitation. Using x-ray photoemission spectroscopy (XPS) and scanning electron microscopy (SEM), we compare the Cu matrix and Co beryllides of well-characterized as-obtained and precipitation hardened alloys. SEM confirms the evolution of the microstructure typical of Guinier-Preston zone formation and precipitation. The binding energies and line shapes of Cu 2p, Co 2p, and Be 1s core levels are investigated using XPS. In spite of the Co beryllides migrating to the grain boundaries as an entity, XPS indicates that the Be atoms get oxidized upon migration, while the Co atoms remain metallic. The Cu 2p core levels shift 0.3 eV to higher binding energy in the as-obtained and partially hardened alloys. In addition, a line shape change observed only in the partially hardened alloy is attributed to strain in the Cu matrix upon Guinier-Preston zone formation. In contrast, for the fully hardened alloy, the binding energy and line shape reverts back to that of pure copper. But for the chemical potential shift, the valence band spectral features exhibit negligible changes in spectral shape upon hardening. The results are consistent with a change in the chemical potential due to metastable Co beryllides and increasing strain in the initial stages of hardening due to Guinier-Preston zones. In the fully hardened alloy, the observed reduction of the chemical potential shift is related to precipitation and a corresponding readjustment of the Fermi energy