Search results for: corrosion prediction ductile fracture

Authors: Roya Moradifar, Naser Agharezaee

Abstract:

In this paper corrosion in the liquid sulphur storage tank at South pars gas complex phases 2&3 is presented. This full hot insulated field-erected storage tanks are used for the temporary storage of 1800m3 of molten sulphur. Sever corrosion inside the tank roof was observed during over haul inspections, in the direction of roof gradient. Investigation shown, in spite of other parts of tank there was no insulation around these manholes. Internal steam coils do not maintain a sufficiently high tank roof temperature in the vapor space. Sulphur and formation of liquid water at cool metal surface, this combination leads to the formation of iron sulfide. By employing a distributed external heating system, the temperatures of any point of the tank roof should be based on ambient dew point and the liquid storage solidification point. Also other construction and operation of tank is more important. This paper will review potential corrosion mechanism and operational case study which illustrate the importance of heating systems.

Keywords: tank, steam, corrosion, sulphur

Procedia PDF Downloads 545

Authors: Nety Trisnawaty, Mirna Febriani

Abstract:

The use of stainless steel wires in the field of dentistry is widely used, especially for orthodontic and prosthodontic treatment using stainless steel wire. The oral cavity is the ideal environment for corrosion, which can be caused by saliva. Prevention of corrosion on stainless steel wires can be done by using an organic or non-organic corrosion inhibitor. One of the organic inhibitors that can be used to prevent corrosion is black tea leaves extracts. To explain the comparison of chromium ions release for stainlees steel between artificial saliva and black tea leaves extracts. In this research we used artificial saliva, black tea leaves extracts, stainless steel wire and using Atomic Absorption Spectrophometric testing machine. The samples were soaked for 1, 3, 7 and 14 days in the artificial saliva and black tea leaves extracts. The results showed the difference of chromium ion release soaked in artificial saliva and black tea leaves extracts on days 1, 3, 7 and 14. Statistically, calculation with independent T-test with p < 0,05 showed a significant difference. The longer the duration of days, the more ion chromium were released. The conclusion of this study shows that black tea leaves extracts can inhibit the corrosion rate of stainless steel wires.

Keywords: chromium ion, stainless steel, artificial saliva, black tea leaves extracts

Procedia PDF Downloads 260

Authors: Han Bing, Yin Zhenjie

Abstract:

In order to analyze the status of a diesel engine, as well as conduct fault prediction, a new prediction model based on a gray system is proposed in this paper, which takes advantage of the neural network and the genetic algorithm. The proposed GBPGA prediction model builds on the GM (1.5) model and uses a neural network, which is optimized by a genetic algorithm to construct the error compensator. We verify our proposed model on the diesel faulty simulation data and the experimental results show that GBPGA has the potential to employ fault prediction on diesel.

Keywords: fault prediction, neural network, GM(1, 5) genetic algorithm, GBPGA

Procedia PDF Downloads 289

Authors: Jianguo Chen, Fenggang Zang, Yu Yang, Liangang Zheng

Abstract:

Reactor Pressure Vessel (RPV) is an important security barrier in nuclear power plant. Crack like defects may be produced on RPV during the whole operation lifetime due to the harsh operation condition and irradiation embrittlement. During the severe loss of coolant accident, thermal shock happened as the injection of emergency cooling water into RPV, which results in re-pressurization of the vessel and very high tension stress on the vessel wall, this event called Pressurized Thermal Shock (PTS). Crack on the vessel wall may propagate even penetrate the vessel, so the safety of the RPV would undergo great challenge. Many assumptions in structure integrity evaluation make the result of deterministic fracture mechanics very conservative, which affect the operation lifetime of the plant. Actually, many parameters in the evaluation process, such as fracture toughness and nil-ductility transition temperature, have statistical distribution characteristics. So it is necessary to assess the structural integrity of RPV subjected to PTS event by means of Probabilistic Fracture Mechanics (PFM). Structure integrity evaluation methods of RPV subjected to PTS event are summarized firstly, then evaluation method based on probabilistic fracture mechanics are presented by considering the probabilistic characteristics of material and structure parameters. A comprehensive analysis example is carried out at last. The results show that the probability of crack penetrates through wall increases gradually with the growth of fast neutron irradiation flux. The results give advice for reactor life extension.

Keywords: fracture toughness, integrity evaluation, pressurized thermal shock, probabilistic fracture mechanics, reactor pressure vessel

Procedia PDF Downloads 234

Authors: Fuyan Sun, Guang Wang, Xueyuan Nie

Abstract:

In this study, a plasma electrolytic oxidation (PEO) process was used to form titanium-aluminium oxide coating on aluminized steel. The present work was mainly to study the effects of treatment time of PEO process on properties of the titanium coating. A potentiodynamic polarization corrosion test was employed to investigate the corrosion resistance of the coating. The friction coefficient and wear resistance of the coating were studied by using pin-on-disc test. The thermal transfer behaviours of uncoated and PEO-coated aluminized steels were also studied. It could be seen that treatment time of PEO process significantly influenced the properties of the titanium oxide coating. Samples with a longer treatment time had a better performance for corrosion and wear protection. This paper demonstrated different treatment time could alter the surface behaviour of the coating material.

Keywords: titanium-aluminum oxide, plasma electrolytic oxidation, corrosion, wear, thermal property

Procedia PDF Downloads 343

Authors: Prashant Parhad, Vinayak Dakre, Ajay Likhite, Jatin Bhatt

Abstract:

This work mainly focuses on machinability studies of Austempered Ductile Iron (ADI). The Ductile Iron (DI) was austempered at 250 oC for different durations and the process window for austempering was established by studying the microstructure. The microstructural characterization of the material was done using optical microscopy, SEM and XRD. The samples austempered as per the process window were then subjected to turning using a TiAlN-coated tungsten carbide insert to study the effect of cutting parameters, namely the cutting speed and the depth of cut. The effect was investigated in terms of cutting forces required as well as the surface roughness obtained. The turning was conducted on a CNC turning machine and primary (Fx), radial (Fy) and feed (Fz) cutting forces were quantified with a three-component dynamometer. It was observed that the magnitude of radial force was more than that of primary cutting force for all cutting speed and for various depths of cut studied. It has also been seen that increasing the cutting speed improves the surface quality. The observed machinability behaviour was investigated in light of the microstructure of the material obtained under the given austempering conditions and a structure-property- co-relation was established between the two. For all cutting speed and depth of cut, the best machining response in terms of cutting forces and surface quality was obtained towards the centre of process window.

Keywords: process window, cutting speed, depth of cut, surface roughness

Procedia PDF Downloads 353

Authors: N. Hammouda, K. Belmokre

Abstract:

The paints are used extensively today in the industry to protect the metallic structures of the aggressive environments. This work is devoted to the study of corrosion resistance and aging behavior of a paint coating providing external protection for oil tankers. To avoid problems related to corrosion of these vessels, two protection modes are provided: An electro chemical active protection (cathodic protection of the hull). A passive protection by external painting. Investigations are conducted using stationary and non-stationary electro chemical tools such as electro chemical impedance spectroscopy has allowed us to characterize the protective qualities of these films. The application of the EIS on our damaged in-situ painting shows the existence of several capacitive loops which is an indicator of the failure of our tested paint. Microscopic analysis (micrograph) helped bring essential elements in understanding the degradation of our paint condition and immersion training corrosion products.

Keywords: epoxy paints, electrochemical impedance spectroscopy, corrosion mechanisms, seawater

Procedia PDF Downloads 379

Authors: K. S. Ghosh, Sagnik Bose, Kapil Tripati

Abstract:

Potentiodynamic polarization studies carried out on AA2024 and AA2014 Al-Cu-Mg alloys of various tempers in 3.5 wt. % NaCl and in 3.5 wt. % NaCl + 1.0 % H2O2 solution characteristic E-i curves. Corrosion potential (Ecorr) value has shifted towards more negative potential with the increase of artificial aging time. The Ecorr value for the alloy tempers has also shifted anodically in presence of H2O2 in 3.5 % NaCl solution. Further, passivity phenomenon has been observed in all the alloy tempers when tested in 3.5 wt. % NaCl solution at pH 12. Stress corrosion cracking (SCC) behaviour of friction stir weld (FSW) joint of AA2014 alloy has been studied bu slow strain rate test (SSRT) in 3.5 wt. % NaCl solution. Optical micrographs of the corroded surfaces of polarised samples showed general corrosion, extensive pitting and intergranular corrosion as well. Further, potentiodynamic cyclic polarization curves displayed wide hysteresis loop indicating that the alloy tempers are susceptible to pit growth damage. Attempts have been made to explain the variation of observed electrochemical and SCC behaviour of the alloy tempers and the electrolyte conditions with the help of microstructural features.

Keywords: AA 2014 and AA 2024 Al-C-Mg alloy, artificial ageing, potentiodynamic polarization, TEM micrographs, stress corrosion cracking (SCC)

Procedia PDF Downloads 312

Authors: Nadia Hammouda, Kamel Belmokre

Abstract:

Organic coatings are widely employed in the corrosion protection of most metal surfaces, particularly steel. They provide a barrier against corrosive species present in the environment, due to their high resistance to oxygen, water and ions transport. This study focuses on the evaluation of corrosion protection performance of epoxy paint on the carbon steel surface in sea water by Electrochemical Impedance Spectroscopy (EIS). The electrochemical behavior of painted surface was estimated by EIS parameters that contained paint film resistance, paint film capacitance and double layer capacitance. On the basis of calculation using EIS spectrums it was observed that pore resistance (Rpore) decreased with the appearance of doubled layer capacitance (Cdl) due to the electrolyte penetration through the film. This was further confirmed by the decrease of diffusion resistance (Rd) which was also the indicator of the deterioration of paint film protectiveness.

Keywords: epoxy paints, carbon steel, electrochemical impedance spectroscopy, corrosion mechanisms, sea water

Procedia PDF Downloads 361

Authors: Babak Dizangian, Mohammad Reza Ghasemi, Akram Ghalandari

Abstract:

Moment frames have considerable ductility against cyclic lateral loads and displacements; however, if this feature causes the relative displacement to exceed the permissible limit, it can impose unfavorable hysteretic behavior on the frame. Therefore, adding a bracing system with the capability of preserving the capacity of high energy absorption and controlling displacements without a considerable increase in the stiffness is quite important. This paper investigates the retrofitting of a single storey steel moment frame through a delayed wire-rope bracing system using a middle steel plate. In this model, the steel plate lies where the wire ropes meet, and the model geometry is such that the cables are continuously under tension so that they can take the most advantage of the inherent potential they have in tolerating tensile stress. Using the steel plate also reduces the system stiffness considerably compared to cross bracing systems and preserves the ductile frame’s energy absorption capacity. In this research, the software models of delayed wire-rope bracing system have been studied, validated, and compared with other researchers’ laboratory test results.

Keywords: cyclic loading, delayed wire rope bracing, ductile moment frame, energy absorption, hysteresis curve

Procedia PDF Downloads 272

Authors: S. Tunmee, P. Wongpanya, I. Toda, X. L. Zhou, Y. Nakaya, N. Konkhunthot, S. Arakawa, H. Saitoh

Abstract:

The hydrogenated amorphous carbon films (a-C:H) were deposited on p-type Si (100) substrates at different thicknesses by radio frequency plasma enhanced chemical vapor deposition technique (rf-PECVD). Raman spectra display asymmetric diamond-like peaks, representative of the a-C:H films. The decrease of intensity ID/IG ratios revealed the sp3 content arise at different thicknesses of the a-C:H films. In terms of mechanical properties, the high hardness and elastic modulus values show the elastic and plastic deformation behaviors related to sp3 content in amorphous carbon films. Electro chemical properties showed that the a-C:H films exhibited excellent corrosion resistance in air-saturated 3.5 wt% NaCl solution for pH 2 at room temperature. Thickness increasing affected the small sp2 clusters in matrix, restricting the velocity transfer and exchange of electrons. The deposited a-C:H films exhibited excellent mechanical properties and corrosion resistance.

Keywords: thickness, mechanical properties, electrochemical corrosion properties, a-C:H film

Procedia PDF Downloads 433

Authors: Serge Mudinga Lemika, Samuel Olukayode Akinwamide, Aribo Sunday, Babatunde Abiodun Obadele, Peter Apata Olubambi

Abstract:

Use of Duplex stainless steel has become predominant in applications where excellent corrosion resistance is of utmost importance. Corrosion behavior of duplex stainless steel induced with varying stress in a chloride media were studied. Characterization of as received 2205 duplex stainless steels were carried out to reveal its structure and properties tensile sample produced from duplex stainless steel was initially subjected to tensile test to obtain the yield strength. Stresses obtained by various percentages (20, 40, 60 and 80%) of the yield strength was induced in DSS samples. Corrosion tests were carried out in magnesium chloride solution at room temperature. Morphologies of cracks observed with optical and scanning electron microscope showed that samples induced with higher stress had its austenite and ferrite grains affected by pitting.

Keywords: duplex stainless steel, hardness, nanoceramics, spark plasma sintering

Procedia PDF Downloads 286

Authors: O. Çomaklı, M. Yazıcı, T. Yetim, A. F. Yetim, A. Çelik

Abstract:

In this work, TiO₂ films were deposited on Cp-Ti substrates by thermal oxidation, DC plasma oxidation, and by the sol-gel method. Microstructures of uncoated and TiO₂ film coated samples were examined by X-ray diffraction and SEM. Thin oxide film consisting of anatase (A) and rutile (R) TiO₂ structures was observed on the surface of CP-Ti by under three different treatments. Also, the more intense anatase and rutile peaks appeared at samples plasma oxidized at 700˚C. The thicknesses of films were about 1.8 μm at the TiO₂ film coated samples by sol-gel and about 2.7 μm at thermal oxidated samples, while it was measured as 3.9 μm at the plasma oxidated samples. Electrochemical corrosion behaviour of uncoated and coated specimens was mainly carried out by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) in simulated body fluid (SBF) solution. Results showed that at the plasma oxidated samples exhibited a better resistance property to corrosion than that of other treatments.

Keywords: TiO₂, CP-Ti, corrosion properties, thermal oxidation, plasma oxidation, sol-gel

Procedia PDF Downloads 266

Authors: Taher S. Ababneh, Taghreed M. A. Jazzazi, Tareq M. A. Alshboul

Abstract:

The inhibiting action against aluminum corrosion by three derivatives of 1,8-bis (benzylideneamino) naphthalene (BN) Schiff base has been investigated by means of DFT quantum chemical calculations at the B3LYP/6-31G(d) level of theory. The derivatives (CBN, NBN and MBN) were prepared from the condensation reaction of 1,8-diaminonaphthalene with substituted benzaldehyde (4-CN, 3-NO₂ and 3,4-(OMe)₂, respectively). Calculations were conducted to study the adsorption of each Schiff base on aluminum surface to evaluate its potential as a corrosion inhibitor. The computational structural features and electronic properties of each derivative such as relative energies and energies of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) have been reported. Thermodynamic functions and quantum chemical parameters such as the hardness of the inhibitor, the softness and the electrophilicity index were calculated to determine the derivative of the highest inhibition efficiency.

Keywords: corrosion, aluminum, DFT calculation, 1, 8-diaminonaphthalene, benzaldehyde

Procedia PDF Downloads 328

Authors: Sami I. Jafar, Sami A. Ajeel, Zaman A. Abdulwahab

Abstract:

The turbine blades used in electric power plants are made of low alloy steel type 52. These blades will be subjected to fatigue and also at other times to fatigue corrosion with aging time. Due to their continuous exposure to cyclic rotational stresses in corrosive steam environments, The current research aims to deal with this problem using the laser cladding method for low alloy steel type 52, which works to re-compose the metallurgical structure and improve the mechanical properties by strengthening the resulting structure, which leads to an increase in fatigue and wears resistance, therefore, an increase in the life of these blades is observed.

Keywords: fatigue, fatigue corrosion, turbine blades, laser cladding

Procedia PDF Downloads 183

Authors: F. C. Amadi, G. C. Enyi, G. G. Nasr

Abstract:

Hydraulic fracturing is one of the most important stimulation techniques available to the petroleum engineer to extract hydrocarbons in tight gas sandstones. It allows more oil and gas production in tight reservoirs as compared to conventional means. The main aim of the study is to optimize the hydraulic fracturing as technique and for this purpose three multi-zones layer formation is considered and fractured contemporaneously. The three zones are named as Zone1 (upper zone), Zone2 (middle zone) and Zone3 (lower zone) respectively and they all occur in shale rock. Simulation was performed with Mfrac integrated software which gives a variety of 3D fracture options. This simulation process yielded an average fracture efficiency of 93.8%for the three respective zones and an increase of the average permeability of the rock system. An average fracture length of 909 ft with net height (propped height) of 210 ft (average) was achieved. Optimum fracturing results was also achieved with maximum fracture width of 0.379 inches at an injection rate of 13.01 bpm with 17995 Mscf of gas production.

Keywords: hydraulic fracturing, optimisation, shale, tight reservoir

Procedia PDF Downloads 413

Authors: Melby Chacko, Jagannath Nayak

Abstract:

6061 Al-SiCp composite was solutionized at 350 °C for 30 minutes and water quenched. It was then underaged at 140 °C (T6 treatment). The aging behaviour of the composite was studied using Rockwell B hardness measurement. Corrosion behaviour of the underaged sample was studied in different concentrations of acetic acid and at different temperatures. Benzimidazole at different concentrations was used for the inhibition studies. Inhibition efficiency of benzimidazole was calculated for different experimental conditions. Thermodynamic parameters were found out which suggested benzimidazole is an efficient inhibitor and it adsorbed onto the surface of composite by mixed adsorption where chemisorption is predominant.

Keywords: 6061 Al-SiCp composite, T6 treatment, corrosion inhibition, chemisorption

Procedia PDF Downloads 380

Authors: Mandlenkosi G. R. Mahlobo, Peter A. Olubambi, Philippe Refait

Abstract:

The aim of this study was to use voltammetry as a method to understand the behaviour of steel in unsaturated soil in the presence of cathodic protection (CP). Three carbon steel coupons were buried in artificial soil wetted at 65-70% of saturation for 37 days. All three coupons were left at open circuit potential (OCP) for the first seven days in the unsaturated soil before CP, which was only applied on two of the three coupons at the protection potential -0.8 V vs Cu/CuSO₄ for the remaining 30 days of the experiment. Voltammetry was performed weekly on the coupon without CP, while electrochemical impedance spectroscopy (EIS) was performed daily to monitor and correct the applied CP potential from the ohmic drop. Voltammetry was finally performed on the last day on the coupons under CP. All the voltammograms were modeled with mathematical equations in order to compute the electrochemical parameters and subsequently deduced the corrosion rate of the steel coupons. For the coupon without CP, the corrosion rate was determined at 300 µm/y. For the coupons under CP, the residual corrosion rate under CP was estimated at 12 µm/y while the corrosion rate of the coupons, after interruption of CP, was estimated at 25 µm/y. This showed that CP was efficient due to two effects: a direct effect from the decreased potential and an induced effect associated with the increased interfacial pH that promoted the formation of a protective layer on the steel surface.

Keywords: carbon steel, cathodic protection, voltammetry, unsaturated soil, Raman spectroscopy

Procedia PDF Downloads 49

Authors: V. E. Bazhenov, A. V. Li, A. A. Komissarov, A. V. Koltygin, S. A. Tavolzhanskii, O. O. Voropaeva, A. M. Mukhametshina, A. A. Tokar, V. A. Bautin

Abstract:

Magnesium-based alloys are considered as effective materials in the development of biodegradable implants. The magnesium alloys containing Mg, Zn, Ca as an alloying element are the subject of the particular interest. These elements are the nutrients for the human body, which provide their high biocompatibility. In this work, we investigated the effect of severe plastic deformation (SPD) on the mechanical and corrosion properties of Mg-Zn-Ca and Mg-Zn-Ca-Mn alloys containing from 2 to 4 wt.% Zn; 0.7 wt.% Ca and up to 1 wt.% Mn. Hot extrusion was used as a method of intensive plastic deformation. The temperature of hot extrusion was set to 220 °C and 300 °C. Metallographic analysis after hot extrusion shows that the grain size in the studied alloys depends on the deformation temperature. The grain size for all of investigated alloys is in the range from 3 to 7 microns, and 3 μm corresponds to the extrusion temperature of 220 °C. Analysis of mechanical properties after extrusion shows that extrusion at a temperature of 220 °C and alloying with Mn increase the strength characteristics and decrease the ductility of studied alloys. A slight anisotropy of properties in the longitudinal and transverse directions was also observed. Measurements of corrosion properties revealed that the addition of Mn to Mg-Zn-Ca alloys reduces the corrosion rate. On the other hand, increasing the Zn content in alloys increases the corrosion rate. The extrusion temperature practically does not affect the corrosion rate. Acknowledgement: The authors gratefully acknowledge the financial support of the Ministry of Science and Higher Education of the Russian Federation in the framework of Increase Competitiveness Program of NUST «MISiS» (No K2-2019-008), implemented by a governmental decree dated 16th of March 2013, N 211.

Keywords: biocompatibility, hot extrusion, magnesium alloys, severe plastic deformation, properties

Procedia PDF Downloads 93

Authors: Philippe Dillien, Patrice Forget, Harald Engel, Olivier Cornu, Marc De Kock, Jean Cyr Yombi

Abstract:

Introduction: Hip fracture precedes commonly death in elderly people. Identification of high-risk patients may contribute to target patients in whom optimal management, resource allocation and trials efficiency is needed. The aim of this study is to construct a predictive score of mortality after hip fracture on the basis of the objective prognostic factors available: Neutrophil-to-lymphocyte ratio (NLR), age, and sex. C-Reactive Protein (CRP), is also considered as an alternative to the NLR. Patients and methods: After the IRB approval, we analyzed our prospective database including 286 consecutive patients with hip fracture. A score was constructed combining age (1 point per decade above 74 years), sex (1 point for males), and NLR at postoperative day+5 (1 point if >5). A receiver-operating curve (ROC) curve analysis was performed. Results: From the 286 patients included, 235 were analyzed (72 males and 163 females, 30.6%/69.4%), with a median age of 84 (range: 65 to 102) years, mean NLR values of 6.47+/-6.07. At one year, 82/280 patients died (29.3%). Graphical analysis and log-rank test confirm a highly statistically significant difference (P<0.001). Performance analysis shows an AUC of 0.72 [95%CI 0.65-0.79]. CRP shows no advantage on NLR. Conclusion: We have developed a score based on age, sex and the NLR to predict the risk of mortality at one year in elderly patients after surgery for a hip fracture. After external validation, it may be included in clinical practice as in clinical research to stratify the risk of postoperative mortality.

Keywords: neutrophil-to-lymphocyte ratio, hip fracture, postoperative mortality, medical and health sciences

Procedia PDF Downloads 399

Authors: Jeonghwan Jeon

Abstract:

With the advent of IPTV in the fierce competition with existing broadcasting system, it is emerged as an important issue to predict how much the adoption of IPTV service will be. This paper aims to suggest a prediction model for adopting IPTV using classification and Ranking Belief Simplex (CaRBS). A simplex plot method of representing data allows a clear visual representation to the degree of interaction of the support from the variables to the prediction of the objects. CaRBS is applied to the survey data on the IPTV adoption.

Keywords: prediction, adoption, IPTV, CaRBS

Procedia PDF Downloads 397

Authors: S. Taghavi Kalajahi, A. Koerdt, T. Lund Skovhus

Abstract:

Cathodic protection (CP) is an electrochemical method to control and manage corrosion in different industries and environments. CP which is widely used, especially in buried and sub-merged environments, which both environments are susceptible to microbiologically influenced corrosion (MIC). Most of the standards recommend performing CP using -800 mV, however, if MIC threats are high or sulfate reducing bacteria (SRB) is present, the recommendation is to use more negative potentials for adequate protection of the metal. Due to the lack of knowledge and research on the effectiveness of CP on MIC, to the author’s best knowledge, there is no information about what MIC threat is and how much more negative potentials should be used enabling adequate protection and not overprotection (due to hydrogen embrittlement risk). Recently, the development and cheaper price of molecular microbial methods (MMMs) open the door for more effective investigations on the corrosion in the presence of microorganisms, along with other electrochemical methods and surface analysis. In this work, using MMMs, the gene expression of SRB biofilm under different potentials of CP will be investigated. The specific genes, such as pH buffering, metal oxidizing, etc., will be compared at different potentials, enabling to determine the precise potential that protect the metal effectively from SRB. This work is the initial step to be able to standardize the recommended potential under MIC condition, resulting better protection for the infrastructures.

Keywords: cathodic protection, microbiologically influenced corrosion, molecular microbial methods, sulfate reducing bacteria

Procedia PDF Downloads 79

Authors: Mohamed A. Hegazy

Abstract:

Most of Poly Vinyl Chloride (PVC) petrochemical companies produce huge amount of byproduct which characterized as carcinogenic liquid-wastes, insoluble in water, highly corrosive and highly offensive. This byproduct is partially use, a small part, in the production of hydrochloric acid and the huge part is a waste. Therefore, the aim of this work was to conversion of such PVC wastes, to an environmentally safe product that act as a corrosion Inhibitor for metals in ‎aqueous media and as a biocide for microorganisms. This conversion method was accomplished mainly to protect the environment and to produce high economic value-products. The conversion process was established and the final product was tested for the toxicity, water solubility in comparison to the crude product. Furthermore, the end product was tested as a corrosion inhibitor in 1M HCl and as a broad-spectrum biocide against standard microbial strains and against the environmentally isolated Sulfate-reducing bacteria (SRB) microbial community.

Keywords: PVC, surfactant, corrosion inhibitor, biocide, SRB

Procedia PDF Downloads 113

Authors: Xianjia Meng, Chuanyong Qu

Abstract:

Compact bone produces fatigue damage under the inevitable physiological load. The accumulation of fatigue damage can change the bone’s micro-structure at different scales and cause the catastrophic failure eventually. However, most tests were limited to the macroscopic modulus of bone and there is a need to assess the microscopic modulus during fatigue progress. In this paper, nano-identation was used to investigate the bone specimen subjected to four point bending. The microscopic modulus of the same area were measured at different degrees of damage including fracture. So microscopic damage can be divided into three stages: first, the modulus decreased rapidly and then They fell slowly, before fracture the decline became fast again. After fracture, the average modulus decreased by 20%. The results of inner and outer planes explained the influence of compressive and tensile loads on modulus. Both the compressive and tensile moduli decreased with the accumulation of damage. They reached the minimum at ending and increased after fracture. The modulus evolution under different strains were revealed by the side. They all fell slowly and then fast with the accumulation of damage. The fractured results indicated that the elastic modulus decreased obviously at the high strain while decreased less at the low strain. During the fatigue progress, there was a significant difference in modulus at low degree of damage. However, the dispersed modulus tended to be similar at high degree of damage, but they became different again after the failure.

Keywords: fatigue damage, fracture, microscopic modulus, bone, nano-identation

Procedia PDF Downloads 146

Authors: Mokali Veeresham

Abstract:

The microstructure and texture evolution of cryo rolled and annealed ductile TaHfNbZrTi refractory high entropy alloy was investigated. To obtain that, the alloy is severely cryo rolled and subsequently annealed for the recrystallization process. The cryo rolled – 90% shows the presence of very fine grains and microstructural heterogeneity. The cryo rolled samples are annealed at a temperature ranging from 800°C to 1400°C, the partial recrystallization is observed at 800°C annealed condition, and at higher annealing temperatures the complete recrystallization process is noticed. The development of ND fiber texture is observed after the annealing.

Keywords: refractory high entropy alloy, cryo-rolling, annealing, microstructure, texture

Procedia PDF Downloads 159

Authors: Ahmed Chetouani

Abstract:

Corrosion is a natural occurring process where it can be defined as the deterioration of materials properties due to its interaction with its environment. Corrosion can lead to failures in plant infrastructure and machines which are usually costly to repair. In terms of loss of contaminated products which will cause environmental damage and possibly costly in terms of human health. The driving force that causes metals to corrode is due to the natural consequence of their temporary existence in metallic form. There is a growing trend in utilizing plant extracts and pharmaceutical compounds as corrosion inhibitors. Exquisite identification of the essential oil of aerial parts of Pelargonium was obtained using hydrodistillation and identification using GC (gas chromatography) and GC/MS (gas chromatography-mass spectrometry). The oil was predominated by Citronellol (22.8%). The inhibitory effect of essential oil and extract of Pelargonium was estimated on the corrosion of mild steel in 1M hydrochloric acid (HCl) using weight loss, Electrochemical Impedance Spectroscopy (EIS) and Tafel polarization curves. Inhibition was found to increase with increasing concentration of the essential oil and extract of Pelargonium. The effect of temperature on the corrosion behaviour of mild steel in 1M HCl with addition of essential oil and extract was also studied and the thermodynamic parameters were determined and discussed. Values of inhibition efficiency were calculated from weight loss, Tafel polarization curves, and EIS. All results are in good agreement. Polarization curves showed that essential oil and extract of Pelargonium behave as mixed type inhibitors in hydrochloric acid. The results obtained showed that the essential oil and extract of Pelargonium could serve as an effective inhibitor of the corrosion of mild steel in Hydrochloric acid solution. To avoid any surprise of toxicity, the majority compounds have been studied by using POM analyses.

Keywords: corrosion inhibition, mild steel, pelargonium oil, extract, electrochemical system, hydrodistillation, side effects, POM Analyses

Procedia PDF Downloads 388

Authors: Chahla Rahal, Philippe Refait

Abstract:

Oleuropein-rich extract from olive leaf and acid hydrolysates, rich in hydroxytyrosol and elenolic acid was prepared under different experimental conditions. These phenolic compounds may be used as a corrosion inhibitor. The inhibitive action of these extracts and its major constituents on the corrosion of copper in 0.5 M NaCl solution has been evaluated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and weight loss measurements. The product of extraction was analyzed with high performance liquid chromatography (HPLC), whose analysis shows that olive leaf extract are greatly rich in phenolic compounds, mainly Oleuropeine (OLE), Hydroxytyrosol (HT) and elenolic acid (EA). After the acid hydrolysis and high temperature of extraction, an increase in hydroxytyrosol concentration was detected, coupled with relatively low oleuropeine content and high concentration of elenolic acid. The potentiodynamic measurements have shown that this extract acts as a mixed-type corrosion inhibitor, and good inhibition efficiency is observed with the increase in HT and EA concentration. These results suggest that the inhibitive effect of olive leaf extract might be due to the adsorption of the various phenolic compounds onto the copper surface.

Keywords: olive leaf extract, oleuropein, voltammetry, copper, corrosion, HPLC, EIS

Procedia PDF Downloads 286

Authors: Wei-Ru Chang, Jenn-Jiang Hwang, Zen-Ting Hsiao, Shu-Feng Lee

Abstract:

Proton exchange membrane (PEM) fuel cells are widely used in electrical systems as an economical, low-polluting energy source. This study investigates the effects of PEMFC gas nitriding treatment on metal bipolar plates. The test material was SUS304 stainless steel. The study explored five different pretreatment processes, varying the corrosion resistance and electrical conductivity conditions. The most effective process was industrial acid washing, followed by heating to 500 °C. Under the condition, the corrosion current density was 8.695 μA, significantly lower than that of the untreated pretreatment sample flakes, which was measured as 38.351 μA.

Keywords: nitriding, bipolar, 304, corrosion, resistance, pretreatment

Procedia PDF Downloads 1063

Authors: Chun-Ying Lee, Mei-Wen Wu, Li-Yi Cheng, Chiang-Ho Cheng

Abstract:

This research studies the electroplating of zinc coating in the zinc chloride bath mixed with supercritical CO2. The sodium fluoride (NaF) was used as the bath additive to change the structure and property of the coating, and therefore the roughness and corrosion resistance of the zinc coating was investigated. The surface characterization was performed using optical microscope (OM), X-ray diffractometer (XRD), and α-step profilometer. Moreover, the potentiodynamic polarization measurement in 3% NaCl solution was employed in the corrosion resistance evaluation. Because of the emulsification of the electrolyte mixed in Sc-CO2, the electroplated zinc produced the coating with smoother surface, smaller grain, better throwing power and higher corrosion resistance. The main role played by the NaF was to reduce the coating’s roughness and grain size. In other words, the CO2 mixed with the electrolyte under the supercritical condition performed the similar function as brighter and leveler in zinc electroplating to enhance the throwing power and corrosion resistance of the coating.

Keywords: supercritical CO2, zinc-electroplating, sodium fluoride, electroplating

Procedia PDF Downloads 549

Authors: Anirudh Sharma

Abstract:

Introduction: The Covid-19 pandemic necessitated a change in the manner outpatient fracture clinics are conducted due to the need to reduce footfall in hospital. While studies regarding virtual fracture clinics have shown these to be useful and effective, they focus exclusively on remote consultations. However, our service was bespoke to the patient – either a face-to-face or telephone consultation depending on patient need – a ‘hybrid virtual clinic (HVC).’ We report patient satisfaction and outcomes with this novel service. Methods: Patients booked onto our fracture clinics during the first 2 weeks of national lockdown were retrospectively contacted to assess the mode of consultations (virtual, face-to-face, or hybrid), patient experience, and outcome. Patient experience was assessed using the net promoter (NPS), customer effort (CES) and customer satisfaction scores (CSS), and their likelihood of using the HVC in the absence of a pandemic. Patient outcomes were assessed using the components of the EQ5D score. Results: Of 269 possible patients, 140 patients responded to the questionnaire. Of these, 66.4% had ‘hybrid’ consultations, 27.1% had only virtual consultations, and 6.4% had only face-to-face consultations. The mean overall NPS, CES, and CSS (on a scale of 1-10) were 7.27, 7.25, and 7.37, respectively. The mean likelihood of patients using the HVC in the absence of a pandemic was 6.5/10. Patients who had ‘hybrid’ consultations showed better effort scores and greater overall satisfaction than those with virtual consultations only and also reported superior EQ5D outcomes (mean 79.27 vs. 72.7). Patients who did not require surgery reported increased satisfaction (mean 7.51 vs. 7.08) and were more likely to use the HVC in the absence of a pandemic. Conclusion: Our study indicates that a bespoke HVC has good overall patient satisfaction and outcomes and is a better format of fracture clinic service than virtual consultations alone. It may be the preferred mode for fracture clinics in similar situations in the future. Further analysis needs to be conducted in order to explore the impact on resources and clinician experience of HVC in order to appreciate this new paradigm shift.

Keywords: hybrid virtual clinic, coronavirus, COVID-19, fracture clinic, remote consultation

Procedia PDF Downloads 122