In this study, the use of nano-silica (nano-SiO2) and bentonite as mortar additives for combating reinforcement corrosion is reported. More specifically, these materials were used as additives in ordinary Portland cement (OPC)/fly ash blended mortars in different amounts. The effects of nano-silica and bentonite addition on compressive strength of mortars at different ages was tested. Accelerated corrosion testing was used to assess the corrosion resistance of reinforced mortar specimens containing different amounts of nano-silica and bentonite. It was found that the specimens containing nano-SiO2 not only had higher compressive strength, but also showed lower steel mass loss due to corrosion compared to reference specimens. However, this was accompanied by a small reduction in workability (for a constant water to binder ratio). Mortar mixtures with 4% of nano-silica were found to have optimal performance in terms of compressive strength and corrosion resistance. Control specimens (OPC/fly ash mortars without any additives) showed low early age strength and low corrosion resistance compared to specimens containing nano-SiO2 and bentonite. In addition, samples from selected mixtures were analyzed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Finally, the influence of Ca/Si ratio of the calcium silicate hydrate (C-S-H) in different specimens on the compressive strength is discussed. In general, the study showed that the addition of nano-silica (and to a lesser extent bentonite) can result in higher strength and corrosion resistance compared to control specimens. Furthermore, the addition of nano-SiO2 can be used to offset the negative effect of fly ash on early age strength development.
The adhesion of colloidal probes of stainless steel, glass and cellulose to Pseudomonas fluorescens biofilms was examined using atomic force microscopy (AFM) to allow comparisons between surfaces to which biofilms might adhere.
An air fin cooler system consists of a tube bundle that is used to cool the various processing fluids in process industries that utilizes air as a cooling medium. The said tubes failed when exposed to corrosive environment(s). Tubes located at the bottom row of the air fin cooler were corroded as a result of exposure to rain water, brought in by induced air when the wind blows. The tube material is A179 Carbon steel. Two tubes, namely Tube A and Tube B along with an aluminum fin in each tube were investigated. A leak was observed on tube A, probably due to Corrosion Under Deposit mechanism. A general corrosion attack was observed at tube B, and macroscopic analysis showed that the corrosion occurred along the grain boundaries, which consist of ferrite and pearlite. Microanalysis showed that the corrosion product on the outer surface of the tube consists of Fe, O, S and Cl elements. It is concluded that the humid environment contains corrosive elements such as S and Cl. EDAX analysis on the fin showed that the material is pure aluminum. However, the aluminum was corroded by galvanized corrosion and produced brittle Al2O3 as a result.
The joining of ceramic-metal could be done through a few techniques: brazing, diffusion bonding, friction welding etc. However, the mechanism of ceramic-metal joining was still not properly understood. In this study, alumina rod was bonded to mild steel rod via friction welding technique by using Al 1100 sheet as interlayer. The diameter of the rods was 10 mm. Friction pressure of 20 MPa and forging pressure of 40 MPa were used. Rotational speeds were maintained at 900 rpm and friction times of 2 to 20 seconds were applied. The joining strength was determined through four point bending test. The maximum bending strength, 240 MPa was obtained at the friction times of 20 seconds. Under optical microscope and SEM observation, the deformation of the aluminum interface was clearly obtained. Mechanical interlocking and close contact between the aluminaaluminum and aluminum-mild steel were observed at magnifications of 3000X. The strength of alumina-steel bonding is much dependent on the wettability of the alumina surface by the molten aluminum and the existing of mechanical interlocking between interlayer and sample materials.
Electrodeposition of white copper-tin alloys (including white miralloys) has been done onto planar mild steel substrates from alkaline cyanide solutions at 65 0 C. The chemical composition of the coating is influenced by plating bath composition and current density. White miralloy can be produced from the test solution containing 10 g/l CuCN2 - , 45 g/l Na2SnO3, 25 g/l NaCN, and 12 g/l NaOH at current density about 5 mA/cm 2 . The local compositions of the coating cross section were analyzed using EDX installed in a FESEM operated at an accelerating voltage of 20 kV. The phases formed during co-deposition process were identified using XRD at 25 mA current and 35 kV voltage.
Present of 241Am in the environment is being determined as part of surveillance and research
programs related to nuclear activities. The separation of 241Am from environmental samples was
carried out against the IAEA’s reference material by using an improved in-house radiochemical
separation method through anion exchange column, followed by the electro-deposition on a
stainless steel disc, and finally assayed on alpha spectrometry counting system. The resulting
spectra showed good isolated peak, indicating a good separation of the radionuclide of interest.
The analytical results were in good agreement with the certified value for IAEA-326 and IAEA-368
with the calculated U-score was 0.36 and 0.82, respectively, showing no significant difference
between the experimental and certified value. Using this method, distributions of 241Am in seabed
surface sediment in the Exclusive Economic Zone of East Coast Peninsular Malaysia were studied.
Samples were collected during June 2008 where the concentrations of 241Am were found to be
ranged from < 0.08 to 0.36 Bq/kg, dry weight.
Steel sections are normally shaped via cold work manufacturing processes. The extent of cold work to shape the steel sections might induce residual stresses in the region of bending. Previously, researchers had performed studies on the influences of local buckling on the failure behavior of steel compression members which shown that failure will happen when most of the yielding has extended to the middle surface in the bend region of the sections. Therefore, these cold work methods may have major effect on the behavior of the steel section and also its load-bearing capability. In addition, another factor may play significant role in formed section's load-bearing capacity which is the longitudinal residual strain. The longitudinal residual strain raised during forming procedure can be used to define the section imperfection of the formed section and its relation to the existence of defects. Therefore, the main motivation of this research paper is to perform three-dimensional finite element (3D-FE) to investigate peak longitudinal residual strains of a thin-walled steel plate with large bending angle along member length. A 3D finite element simulation in ABAQUS has been employed to simulate this forming process. The study concluded that the longitudinal residual strain at the section corner edge was higher than those at the rest of the corner region. These strains at the edge were higher than the yield strain
(
ε
y
)
of the formed section which occurred due to the lack of transverse restraint. This made the plate edge tended to bend toward the normal direction when it was under a high transverse bending. This causes a significant difference in longitudinal strain at the plate edge.
Carabiner is one of Personal Protective Equipment (PPE), which is used to protect the users from hazards by reducing any chance of serious injury. Thus, it is very important to detect even a small
defect on the component before it becomes worse that could give harm to the users. The aim of this paper is to find out the appropriate imaging technical factors of steel carabiner by using computed radiography (CR). Methods: Radiographic images of carabiner were obtained by manipulating the values of kVp and mAs with respect to contrast and density. A preliminary study was carried out to determine the exposure factor combination in order to produce perceptible visual quality of radiographic images. Positioning techniques applied in this study were whole view (open-gate and close-gate position) and screw view (open-gate and close-gate position). An assessor was invited to evaluate the radiographs by using Image Quality Criteria Scoring (ICS) adapted from European Guidelines on Quality Criteria for Diagnostic Radiographic Images. Results: Findings showed that the optimum values of kVp and mAs in imaging whole view (open-gate and close-gate) carabiner were 133 kVp and 28 mAs while, for screw view (opengate and close-gate) the range of kVp and mAs preferred were 121 kVp to 133 kVp and 28 mAs to 36 mAs respectively. Conclusion: This study has found that the use of medical CR to expose metal steel such as
carabiner is accepted. By manipulating the imaging parameters, CR can produce a good quality image of carabiner.
Iron and steel industries are among the contributors of CO2 emission in large volume into the atmosphere, causing detrimental effects to the environment and the ecosystem at large scale. These industries also generate solid wastes in the form of electric arc furnace (EAF) slag during operations which result in about 10-15% slag wastes per ton of steel produced. In this study, the EAF slags from an iron and steel-making factory in Klang, Malaysia was utilized for CO2 sequestration through direct aqueous mineral carbonation. According to the surface area analysis, the fresh EAF slag has a mesoporous structure, its elemental composition shows the presence of 20.91 wt.% of CaO that was used for the sequestration of CO2 through carbonation. The sequestration capacity was found to be 58.36 g CO2/kg of slag at ambient temperature in 3 h, with the liquid/solid (L/S) ratio of 5:1 and using <63μm particle size. Moreover, the shrinking core model (SCM) was used to analyze the solid-fluid reaction in a heterogeneous phase and the CO2 sequestration shows to be controlled by the product layer phase. The EAF slag is demonstrated to have the potential of CO2 sequestration at ambient temperature.
Anatomically precontoured plates are commonly used to treat periarticular fractures. A well-fitting plate can be used as a tool for anatomical reduction of the fractured bone. Recent studies highlighted that some plates fit poorly for many patients due to considerable shape variations between bones of the same anatomical site. While it is impossible to design one shape that fits all, it is also burdensome for the manufacturers and hospitals to produce, store and manage multiple plate shapes without the certainty of utilization by a patient population. In this study, we investigated the number of shapes required for maximum fit within a given dataset, and if they could be obtained by manually deforming the original plate. A distal medial tibial plate was automatically positioned on 45 individual tibiae, and the optimal deformation was determined iteratively using finite element analysis simulation. Within the studied dataset, we found that: (i) 89% fit could be achieved with four shapes, (ii) 100% fit was impossible through mechanical deformation, and (iii) the deformations required to obtain the four plate shapes were safe for the stainless steel plate for further clinical use. The proposed framework is easily transferable to other orthopaedic plates.
The protection of concrete structures against corrosion in marine environments has always been a challenge due to the presence of a saline solution-A natural corrosive agent to the concrete paste and steel reinforcements. The concentration of salt is a key parameter influencing the rate of corrosion. In this paper, we propose an optical fiber-based salinity sensor based on bundled multimode plastic optical fiber (POF) as a sensor probe and a concave mirror as a reflector in conjunction with an intensity modulation technique. A refractive index (RI) sensing approach is analytically investigated and the findings are in agreement with the experimental results. A maximum sensitivity of 14,847.486/RIU can be achieved at RI = 1.3525. The proposed technique is suitable for in situ measurement and monitoring of salinity in liquid.
Extracts from plant materials have great potential as alternatives to inorganic corrosion inhibitors, which typically have harmful consequences. Experimental and theoretical methodologies studied the effectiveness of agricultural waste, namely, date palm seed extract as a green anti-corrosive agent in 0.5 M hydrochloric acid. Experimental results showed that immersion time and temperature are closely related to the effectivity of date palm seed as a corrosion inhibitor. The inhibition efficiency reduced from 95% to 91% at 1400 ppm when the immersion time was increased from 72 h to 168 h. The experimental results also indicated that the inhibition efficiency decreased as the temperature increased. The presence of a protective layer of organic matter was corroborated by scanning electron microscopy. The adsorption studies indicated that date palm seed obeyed Langmuir adsorption isotherm on the carbon steel surface, and Gibbs free energy values were in the range of -33.45 to -38.41 kJ·mol-1. These results suggested that the date palm seed molecules interacted with the carbon steel surface through mixture adsorption. Theoretical calculations using density functional theory showed that the capability to donate and accept electrons between the alloy surface and the date palm seed inhibitor molecules is critical for adsorption effectiveness. The HOMO and LUMO result indicated that the carboxyl (COOH) group and C=C bond were the most active sites for the electron donation-acceptance type of interaction and most auxiliary to the adsorption process over the Fe surface.
The emission of Extreme Ultra Violet (EUV) from plasma produced by vacuum spark discharge using stainless steel as anode material was investigated. The operating pressure for all the experiments carried out was maintained at below 10-4 mbar. The discharge voltage tested was from 8 kV to 20 kV. The inter-electrode distance suitable for high intensity and reproducible EUV emissions was found to be in the range of 2.6 mm to 4.6 mm. The output EUV energy scaled as ~ V02, where V0 is the discharge voltage.
Even though EDXRF analysis has major advantages in the analysis of stainless steel samples such as simultaneous determination of the minor elements, analysis can be done without sample preparation and non-destructive analysis, the matrix issue arised from the inter element interaction can make the the final quantitative result to be in accurate. The paper relates a comparative quantitative analysis using standard and standardless methods in the determination of these elements. Standard method was done by plotting regression calibration graphs of the interested elements using BCS certified stainless steel standards. Different calibration plots were developed based on the available certified standards and these stainless steel grades include low alloy steel, austentic, ferritic and high speed. The standardless method on the other hand uses a mathematical modelling with matrix effect correction derived from Lucas-Tooth and Price model. Further
improvement on the accuracy of the standardless method was done by inclusion of pure elements into the development of the model. Discrepancy tests were then carried out for these quantitative methods on different certified samples and the results show that the high speed method is most reliable for determining of Ni and the standardless method for Mn.
Microbial fuel cells (MFCs) have a high potential application for simultaneous wastewater treatment and electricity
generation. However, the choice of the electrode material and its design is critical and directly affect their performance.
As an electrode of MFCs, the anode material with surface modifications is an attractive strategy to improve the power
output. In this study, stainless steel (SS) and carbon steel (CS) was chosen as a metal anode, while graphite felt (GF)
was used as a common anode. Heat treatment was performed to convert SS, CS and GF into efficient anodes for MFCs.
The maximum current density and power density of the MFC-SS were achieved up till 762.14 mA/m2
and 827.25 mW/m2
,
respectively, which were higher than MFC-CS (641.95 mA/m2
and 260.14 mW/m2
) and MFC-GF (728.30 mA/m2
and 307.89
mW/m2
). Electrochemical impedance spectroscopy of MFC-SS showed better catalytic activity compared to MFC-CS and
MFC-GF anode, also supported by cyclic voltammetry test.
This report aimed to describe an effective biomechanics to control the upper incisors inclination during the
correction of gummy smile with bimaxillary proclinations. A 14-year-old female presented with a Class II
division I incisor relationship complicated with bimaxillary proclination on a Class 2 skeletal base. The lips
were incompetent, showing 7 mm of upper incisors at rest and 5mm maxillary gingival display on smiling
with normal upper lip length. Treatment involved extraction of all first permanent premolars followed by
upper and lower fixed appliances. Intrusion of the upper incisors with controlled labial crown torque was
accomplished with mini-implant anchorage placed bilaterally on the infrazygomatic crests with the retraction
forces above the centre of resistance using 0.019x0.025-in stainless steel archwire in 0.022-in slot. The
0.019x0.025-in stainless steel archwire in 0.022-in slot provided the vertical play to favour lingual crown
tipping despite having forces above the centre of resistance for concurrent anterior segment intrusion.
Evaluation of magnetic properties of electrical steel is vital in improving the quality of electrical machinery since it is used as magnetic cores for transformers, motors and generators. A double yoke single sheet tester (ssT) was modeled using two identical C-cores wound with copper wires at limb side in horizontal arrangement. The magnetic properties for electrical steels, grade M4 and M19 were tested under a frequency of 50 Hz with the current ranging from 02 to 2.4A. The effects of the sample dimension and anisotropy on magnetic measurements were investigated. Evaluation on specimen dimensions indicate that the non-uniformity of sample magnetization in overhang sample can attribute to the flux leakage between the yoke legs. The stray flux is also increased with the overhang sample. However, the so-called fit-in sample which is fitted nicely between the yoke end poles can minimize the effect of stray flux. One way ANOVA and T-test were used as statistical methods and executed at the 5% significance level. It is statistically proven that the magnetic properties of both magnetic materials are influenced by their anisotropy.
Corrosion is a natural deterioration process that destructs metal surface. Metal of highly
protected by passivation layer such as Stainless Steel 316L also undergoes pitting corrosion
when continuously exposed to aggressive environment. To overcome this phenomenon, application
of epoxy based coating with addition of zinc oxide- poly (3,4-ethylenedioxythiophene)
doped with poly (styrene sulphonate) hybrid nanocomposite additive was introduced as
paint/metal surface coating. The compatibility between these two materials as additive
was studied by Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD),
Field Emission Scanning Electron Microscopy/Energy-Dispersive X-ray spectroscopy (FESEM/EDX)
and Transmission Electron Microscopy (TEM) analysis. The effect of nanocomposite
wt.% in epoxy based coating with immersion duration in real environment on corrosion
protection performance was analyzed through potentiodynamic polarization analysis. The
main finding showed that addition of hybrid nanocomposite had increased corrosion protection
yet enhanced corrosion process when excess additives was loaded into epoxy coating.
Addition of 2 wt.% ZnO-PEDOT:PSS was found significantly provided optimum corrosion
protection to stainless steel 316L as the corrosion rate for 0 day, 15 days and 30 days of
immersion duration is 0.0022 mm/yr, 0.0004 mm/yr and 0.0015 mm/yr; respectively.
High strength concrete (HSC) has lower ductility, but higher in strength compared to normal strength concretes. The strength and ductility of HSC can be improved by applying external confinement, such as steel strapping tensioning technique (SSTT). However, SSTT was literately reported effective in confining circular specimens, but the effectiveness of SSTT on square cross section specimens are yet well investigated. This study focuses on HSC square cross section specimens with different corner ratio, which were right angle and rounded corner. In addition, the effect of different number of layer of steel straps confining around the specimens under optimum lateral pre-tensioning stress also been investigated. The number of layers was fixed to two layers and four layers. Fifteen HSC specimens with dimension of 88 mm x 88 mm x 200 mm, which consist of three unconfined specimens, six right angle specimens, and six rounded corner specimens were prepared and tested monotonically to failure. The experimental results show that the strength and ductility of HSC improved significantly by using rounded corner confined specimens and higher number of layer of confinements. This is due to more uniform confining pressure was exerted on entire surface of rounded corner confined specimens. The strength and ductility of the specimens can be improved up to 53.7% and 207.5% respectively.
Detection of cracks from stainless steel pipe images is done using contrast stretching technique. The technique is based on an image filter technique through mathematical morphology that can expose the cracks. The cracks are highlighted and noise removal is done efficiently while still retaining the edges. An automated crack detection system with a camera platform has been successfully implemented. We compare crack extraction in terms of quality measures with those of Otsu's threshold technique and the another technique (Iyer and Sinha, 2005). The algorithm shown is able to achieve good results and perform better than these other techniques.