Mobbassar Hassan Sk

University of Cambridge | Cam · BP Institute for multiflow and Department of Chemistry

We present the corrosion of an iron film in brine solution (0.1 NaCl) as measured by liquid TEM. Dissolution of the iron film and nucleation of the corrosion products is captured by imaging. It shows that nucleation initiates at the metal surface, with preferential growth along the metal grain boundaries. The corrosion product that forms is charact...

Here, we report the design and successful implementation of an ultra-low oxygen sample cell for use on the SAXS-WAXS (small-wide angle x-ray scattering) beamline I22 at DIAMOND. The rigorous exclusion of oxygen is found to require double jacketing with purge gas throughout the entire system, pipework, pumps, and the sample cell itself. This particu...

Confocal Raman imaging and spectroscopy has been used in a custom-made flow-cell to map in-situ spatial and temporal growth of siderite and chukanovite on pipeline steel in a hot brine environment, under conditions typical of commercial interest (pH 6.8, temp 80 o C, oxygen conc < 10 ppb, 0.5 M NaCl, open circuit potential (OCP)). Ferrite and pearl...

The effect of different doses of gamma-ray irradiation has been investigated on zinc tin oxide thin film transistors fabricated via the sol-gel spin-coating method. A negative threshold voltage shift was observed for 10 MRad gamma irradiation dose but the shift became positive after higher radiation doses (50 MRad and 100 MRad). The drain current s...

The effects of the presence of trace H 2 S (∼ 0.5 μM total dissolved H 2 S) on the electrocrystallization of siderite on plain carbon steel and its various micro-alloyed counterparts are explored. This small concentration of H 2 S in a CO 2 saturated (sweet) brine (0.5 M NaCl), at 80°C, in a slightly acidic environment (pH 6.6) at the elevated temp...

A set of bottom-gate Zinc Oxide (ZnO) thin film transistors (TFTs) with active layers containing 1, 4 and 8 layers of spin-coated ZnO were fabricated and their electrical characteristics such as transistor transfer and capacitance-voltage characteristics were analyzed. The transconductance of the single-layered ZnO transistor shows a single peak. O...

The dry erosion behavior of API-X120 pipeline steel was investigated, under the erosive interaction of aluminum oxide particulates, in a range of speed (43–167 m·s−1) and impact angle (30°–90°). Erosion behavior is characterized by surface profile measurement, weight loss measurement, and surface morphology analysis by SEM/EDX. Optical profilometry...

In this letter, the enhancement in electrical characteristics of the thin film transistors (TFTs) based on the mixed-stacked amorphous zinc tin oxide (a-ZTO) with alternating precursor concentration is reported. The channel layers were deposited via sol-gel on oxidized p-Si. The source/drain ohmic contacts were prepared on the ZTO layer, constructi...

Grazing-incidence small-angle X-ray scattering (GISAXS) from polycrystalline steel shows features associated with the underlying microstructure, and, in the initial stages of corrosion, with the development of very small-scale surface roughness, on the nanometer height scale. A 1Cr0.25Mo pipeline steel in hot, CO 2-saturated brine develops the very...

The effect of low concentrations of oxygen on the anodic dissolution of carbon steel in CO 2-saturated aqueous NaCl at 80 • C is simply to change the dissolution product from colloidal amorphous material assumed to be amorphous ferrous carbonate to a crystalline carbonate green rust, Fe 6 (OH) 12 CO 3 , which forms rapidly. This material is deposit...

We report on the fabrication and electrical characterization of bottom gate thin-film transistors (TFTs) based on a sol-gel derived ZnO channel layer. The effect of annealing of ZnO active channel layers on the electrical characteristics of the ZnO TFTs was systematically investigated. Photoluminescence (PL) spectra indicate that the crystal qualit...

The effects of micro-alloying of plain carbon steel with Cr and Mo on the corrosion behavior in CO 2-saturated (sweet) brine (0.5 M NaCl, pH 6.6) environment, under hydrodynamic conditions, at 80 • C were investigated. Crystalline siderite/chukanovite scales formed on all the alloys. Analysis of potentiostatic current transient data suggest that th...

The effects of micro-alloying of plain carbon steel with Cr and Mo on the corrosion behavior in CO2-saturated (sweet) brine (0.5 M NaCl, pH 6.6) environment, under hydrodynamic conditions, at 80◦C were investigated. Crystalline siderite/chukanovite scales formed on all the alloys. Analysis of potentiostatic current transient data suggest that there...

We investigate the effects of the presence of trace (100 vppm) H2S on the corrosion behaviour of plain carbon steel and its various micro-alloyed counterparts in a CO2 saturated (sweet) brine (0.5 M NaCl) environment, in a high flow regime (1000 RPM), at 80oC in a slightly acidic environment (pH 6.6). Potentiostatic current transients indicate that...

In combating CO 2 corrosion, literature suggests specific micro -alloying (< 2 wt. %) of plain carbon steel to be the best choice in consideration of durability to cost ratio. In order to achieve optimized steel chemistry, the effects of number of alloying elements on the corrosion behaviour and protectiveness of the corrosion scale have been studi...

By correlating in-situ synchrotron X-ray diffraction measurements with electrochemical measurements using a rotating disc electrode, we demonstrate the critical dependence on the local supersaturation of the kinetics of formation of a protective crystalline scale on the surface of carbon steel during CO2 corrosion in brine at elevated temperature....

In this paper, the authors report the device instability of solution based ZnO thin filmtransistors by studying the time-evolution of electrical characteristics during electrical stressing and subsequent relaxation. A systematic comparison between ambient and vacuum conditions was carried out to investigate the effect of adsorption of oxygen and wa...

A significant amount of literature exists demonstrating the effect of CO2 on corrosion scale formation under non-flow conditions. However, literature available on the effects of flow on the nature and protectivity of corrosion scale has many contradictions. This work demonstrates the effects of flow on the nature of corrosion scale for five differe...

A significant amount of literature exists demonstrating the effect of CO 2 on corrosion scale formation under non-flow conditions and its pH and temperature dependent protectivity. However, little information is available on the effects of flow on the nature and protectivity of corrosion scale. This work demonstrates the effects of flow on 4 differ...

Time-resolved photocurrent (TRPC) spectroscopy with a variable-wavelength sub-bandgap light excitation was used to study the dynamics of the decaying photocurrent generated in the heterostructures of the AlGaN/GaN high electron mobility transistors (HEMTs) layers. In AlGaN/GaN HEMTs, reliability of the device is degraded due to the prevalence of cu...

Quantitative fractographic characteristics of 4340 steel is demonstrated for a grain size range of 10−100 µm and hardness range of 41–52 HRC. Double-notched tensile samples were electrochemically charged in-situ with hydrogen in 0.5 m H2SO4+5 mg/l As2O3 solution for 0–40 min charging time. Hydrogen induced fracture initiations were analyzed by nove...

Despite the availability of the detailed knowledge about the chemical, electrochemical and transport processes associated with the formation of ferrous carbonate during CO 2 - corrosion of mild steel, information available about the mechanism of early nucleation stages of FeCO 3 (siderite) film formation was only speculative. In depth knowledge rel...

Fractographic behaviors of electrochemically hydrogenated low alloy 4340 steel samples were compared with low temperature (liquid N 2 ) treated samples of same grain sizes and hardnesses. 4340 samples of grain size range of 10-100 μm and hardness range of 41-52 HRC were electrochemically charged with hydrogen in 0.5 M H 2 SO 4 + 5 mg/l As 2 O 3 sol...

In spite of the excellent resistance of stainless steel (SS) towards uniform corrosion, overcoming various localized corrosion could be a real challenge. This work presents an analysis of the failure behavior of 316L SS air chiller tube with a peripheral crack used in a Qatari gas company in Qatar. Macroscopic failure characteristics were analyzed...

We have demonstrated that the depth-dependent defect distribution of the deep level traps in the AlGaN/GaN high electron mobility transistor (HEMT) epi-structures can be analyzed by using the depth-resolved ultra-violet (UV) spectroscopic photo current-voltage (IV) (DR-UV-SPIV). It is of great importance to analyze deep level defects in the AlGaN/G...

The effect of hydrogen on the fracture characteristics of low alloy 4340 steel was studied using double-notched tensile samples electrochemically charged in situ with hydrogen in 1N H2SO4 + 5mg/l As2O3 solution. Fracture behaviors of samples with prior austenitic grain sizes of 10 and 40 μm and martensitic hardness of 43-52 HRC (Rockwell hardness,...

The effect of strain rate on hydrogen embrittlement of low alloy 4340 steel was studied using double-notched tensile samples electrochemically charged in-situ with hydrogen in 1N H2S04 + 5 mg/1 As203 solution. The mechanical response of samples with prior austenitic grain sizes of 10 and 40 μm and martensitic hardness of 43-52 HRC were examined aft...

The effect of hydrogen on embrittlement of low alloy 4340 steel was studied using double-notched tensile samples that were electrochemically charged in-situ with hydrogen in a 1N H2SO4 + 5 mg/l As 2O3 solution. The mechanical response of samples with prior austenitic grain sizes of 10, 40 and 100 μm with martensitic hardness of 40-52 HRC were exami...

Hydrogen peroxide vapor has been proposed as a sterilant/decontaminant for usage in buildings and transportation vehicles including emergency vehicles, buses, trains and aircraft. Although the efficacy of the process has been demonstrated, questions regarding the compatibility of vaporized hydrogen peroxide treatments with the many diverse material...

Infected passengers can unintentionally contaminate the interior of aircraft; deliberate biological contamination from criminals and international adversaries is also possible. Previous work has provided information regarding the delivery mechanism and capability of STERIS Corporation's Vaporized Hydrogen Peroxide (VHP*) technology as a decontamina...

A response to the chemical or biological contamination of aircraft requires the use of a suitable decontaminant. Among possible chemical decontaminants, vapour phase hydrogen peroxide appears to be a likely candidate in terms of a combination of efficacy, low environmental impact and potential for materials compatibility. The present paper examines...