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Search Results: 1 - 10 of 14369 matches for " pitting corrosion resistance "
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Corrosion resistance of metallic implants used in bone surgery
M. Kiel,A. Krauze,J. Marciniak
Archives of Materials Science and Engineering , 2008,
Abstract: Purpose: The purpose of the research was analysis of influence of mechanical damages on the implants’ surfacemade of Cr-Ni-Mo steel on the pitting corrosion resistance. Analysis was performed for implants after differenttime of implantation applied for stabilization of the funnel chest and for stabilization bone fractures, as well as forintramedullary nails in the initial state.Design/methodology/approach: Research were performed on three groups of implants after differentimplantation time. Research were based on the potentiodinamic tests by recording the anodic polarization curves.The tests were performed in the Tyrode’s physiological solution.Findings: The research effect was determination the corrosion potential Ecorr and breakdown potential Eb for threegroups of implants after different time of implantation and different mechanical surface damages. On the basis ofinvestigation it was stated that for all implants the breakdown potential was in the range of Eb = +549 – +1017 mVand the corrosion potential was in the range of Ecorr = -143 – +103 mV.Research limitations/implications: The obtained results can be applied to comparing the effects of possiblepostoperative complications. They also show the relation between the damage of surface layers and implantationtime. The values of corrosion and breakdown potentials indicate good corrosion resistance of the applied austeniticstainless steel.Practical implications: The essential influence on the corrosion resistance had the time of implantation andsize of surface damages. The results of research of implants made of Cr-Ni-Mo austenitic stainless steel presentsthat the steel was performed quality requirements for metallic biomaterials used for tested implants.Originality/value: The work presents the results of pitting corrosion tests for metallic implants made of Cr-Ni-Mo steel in the initial state and after different implantation time.
Corrosion behaviour of plastically deformed high-Mn austenitic steels
A. Grajcar,W. Krukiewicz,S. Ko?odziej
Journal of Achievements in Materials and Manufacturing Engineering , 2010,
Abstract: Purpose: The aim of the work was the comparison of corrosion resistance in an aqueous sulfuric acid solution of two high-manganese austenitic steels of the 0.05C-25Mn-Al-Si-Nb-Ti type in a plastically deformed state.Design/methodology/approach: Investigations were carried out on specimens obtained from a thermo-mechanically rolled sheet and then plastically deformed through bending and immersed in corrosive solutions (1N H2SO4) for 100 hours. The mass decrement was calculated by the gravimetric method, whereas the character of corrosion damages was observed in metallographic investigations using light and scanning electron microscopes both in the polished and etched states.Findings: It was found that after the thermo-mechanical processing one steel is characterized by an austenitic structure with numerous annealing twins, whereas in the second steel lamellar martensitic phases in an austenitic matrix occur. The investigations showed that the examined high-manganese steels have very low corrosion resistance in normal H2SO4. Higher impact on the corrosion resistance than the phase composition has the chemical composition. The mass decrement of the steel with martensite plates is a bit higher than that witha single-phase austenitic matrix. The specimens were intensively dissolved due to general corrosion accompanying by pitting and hydrogen cracking.Research limitations/implications: To investigate in more detail the corrosion behaviour of high-manganese austenitic steels, the polarization tests and the analysis of corrosion products should be carried out.Practical implications: The obtained results can be used for searching the appropriate way of improving the corrosion resistance of high-strength high-manganese austenitic steels.Originality/value: The corrosion resistance of two types of advanced high-manganese austenitic steels with different initial structures was compared. Hydrogen impact in austenitic steels was discussed.
Corrosion Rate Evaluation of the Copper Cable Used in Grounding Systems at the ICE - Costa Rica
Tres,G.; Saborio,E.;
Portugaliae Electrochimica Acta , 2004,
Abstract: this research was made to determine the corrosion rate of the copper cable used in grounding and lightning systems, at the electrical generation plants from the costarrican electrical institute. the methods used were linear polarization resistance (lpr), and the weight loss one. this report includes both, laboratory and field tests of corrosion rates, using as electrolytes two products commercially available. moreover, some electrochemical experiments were developed at the laboratory, in order to know the reaction mechanisms. the goal of this study was to generate criteria for the maintenance and/or the substitution of copper cables according to their deterioration. the results showed that the corrosion rate in "a" is at least ten times higher than in "b". in addition, several samples in the "a" electrolyte had pitting corrosion. the study indicates that from the point of view of the corrosion it is preferable to use product "b" like filling, since the generalized corrosion of copper is lower and in addition localized damage does not appear.
Influência da rugosidade na resistência à corros?o por pite em pe?as torneadas de a?o inoxidável superaustenítico
Gravalos, Márcio Tadeu;Martins, Marcelo;Diniz, Anselmo Eduardo;Mei, Paulo Roberto;
Rem: Revista Escola de Minas , 2010, DOI: 10.1590/S0370-44672010000100013
Abstract: pitting corrosion resistance has been correlated to the morphological conditions of the surface: a smooth surface finishing decreases the potential for pitting. this study aimed at investigating the relationship between pitting corrosion resistance and surface roughness in the machined surfaces of superaustenitic stainless steel astm a744 grade cn3mn. the samples of the casting steel were cylindrically turned sunder different combinations of cutting conditions, producing different surface roughness patterns. the surfaces of the samples, as machined, were characterized by roughness and hardness. after the application of an accelerated immersion corrosion test, these surfaces were examined in a stereoscope and the weight loss by corrosion was also determined. it was revealed that the samples exhibited different corrosion resistance behaviors, according to the machining conditions applied. a correlation between pitting resistance corrosion and machined surface roughness was evident, and also, the weight loss due to the formation of pits. this study has identified that corrosion can be controlled through the selection of appropriate machining parameters.
Steel Pitting Corrosion Analysis, Using a High Vaccum Epoxy Penetration Technique  [PDF]
Gerardo Zavala Olivares, Mónica J. Hernández Gayosso, Rafael García Esquivel
Materials Sciences and Applications (MSA) , 2013, DOI: 10.4236/msa.2013.41002
Abstract:

An epoxy penetration technique was used to reproduce and analyze the pitting corrosion process occurred at a steel coupon surface. The samples were exposed to the resin under high vacuum conditions, in order to fulfill the pits caused by the corrosion process. With this technique, a 3D image of the corrosion damages was obtained. Once the image of the damaged surface was obtained, a Scanning Electron Microscope (SEM) was used to analyze the morphology of the pits exhibited by the steel sample. The results were satisfactory, as different parameters such as the diameter, shape and depth of the pits originated, along with the corrosion preferential path, could be established. According to the results, the use of the epoxy penetration technique may be considered as alternating pitting corrosion analysis technique.

Effect of Temperature on Pitting Corrosion Resistance of 316 Stainless Steel Coated by Cerium Oxide Film in 3.5% NaCl Solution

HHasannejad TShahrabi ASabour Rouhaghdam MAliofkhazraei,

材料科学技术学报 , 2008,
Abstract: One of the main problems of stainless steel is its poor pitting corrosion resistance in the aggressive environment containing Cl-, such as seawater. In this paper we investigated the corrosion behavior of the 316 stainless steel coated by cerium oxide nanocoating prepared by sol-gel process. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were used to study the corrosion behavior of cerium oxide nanocoatings in 3.5% NaCI solution. The microstructure of the cerium oxide was examined by scanning electron microscopy (SEM) and the formed phases was identified by X-ray diffraction (XRD). The pitting corrosion resistance of the cerium oxide nanocoating was found to be improved after heat treatment of the cerium oxide nanocoating at 300~C for 30 rain.
MICROSTRUCTURE AND CORROSION RESISTANCE OF LASER SURFACE ALLOYING PLASMA SPRAYED Cr-Mo COATING
LIANG Yong WANG Jun TONG Baiyun SI Zhongyao Institute of Metal Research,Academia Sinica,Shenyang,China,
LIANG Yong WANG Jun TONG Baiyun SI Zhongyao Institute of Metal Research
,Academia Sinica,Shenyang,China

金属学报(英文版) , 1992,
Abstract: The precipitation of χ-phase,σ-phase and carbides may be restrained or eliminated by lasermelting the plasma sprayed Cr-Mo alloy coating,in which austenite of abundant block usual-ly occurred on medium carbon low alloying steels.The corrosion resistance of this coating to0.5mol/L H_2SO_4 was examined to be superior to that of 18-8 stainless steel.The laser al-loying Cr-Mo coating also has excellent resistance to pitting corrosion,and no pitting ap-peared even it immersed in a medium containing Cl~- ions.
Pitting Corrosion Investigation of Cantilever Beams Using F. E. Method  [PDF]
Jacob Nagler
World Journal of Mechanics (WJM) , 2013, DOI: 10.4236/wjm.2013.32007
Abstract:

Carbon steel cantilever beams are widely used in many applications in aerospace, civil and mechanical engineering. Pitting corrosion is a phenomenon which places severe limitations on the design of such applications. As such, understanding this phenomenon and the methods to deal with it, are of a great importance. This paper presents numerical investigation by using F. E. (Finite Element) simulation on the load carrying capacity of corroded cantilever beams with pitting corrosion damage. The pitting corrosion hole shape has been modeled using ASTM G46 Standard Guide. Several different cases of pitting corrosion, represented by hemispherical holes, were modeled and examined by using ANSYS computer program. Clamped edge constraint was used on one end, while the other end was free. In these F. E. models, element of Solid95 was used and comparison to Bernoulli-Euler theory was made. The effect of the radius of the pitting corrosion holes on the stresses in the beam was examined in comparison to yield stress. It has been found that the M. S. (Margin of Safety) has been reduced gradually with increasing radii. Agreement with Bernoulli-Euler theory has been achieved only for small radii. Moreover, three methods of pitting corrosion repairs were examined, together with Bernoulli-Euler theory comparison: 1) Regular surface repair; 2) Extension surface repair; and 3) Handy Removal. It was found that extension surface repair has the highest M. S. value.

Corrosion Characteristics of Ascast Ductile Iron in Lime Juice  [PDF]
F.O. Aramide, E.O. Olorunniwo, P.O. Atanda, J.O. Borode
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2010, DOI: 10.4236/jmmce.2010.910063
Abstract: A study on the corrosion characteristics of ascast ductile iron in lime juice was conducted using the common weight loss method. Five standard tensile samples were prepared from the ascast condition of the alloy. One of them was taken to be for control, while the others were labeled A, B, C, and D. These labeled samples were then immersed in freshly extracted lime juice for a period of four weeks, having noted their respective initial weights. A sample was withdrawn from the medium at the end of each week for microstructural and tensile properties (using INSTRON 1195 at a fixed crosshead speed of 10mm min-1) examination for comparison with those of the control sample. It was observed that the mechanical properties of the alloy were deteriorating due to pitting corrosion and that the corrosion rate increases with increase in the pH of the medium. It was concluded that corrosion rate can be kept to the minimum by controlling the pH of the media within the range 2.0 to 3.05.
Effects of Anodizing Parameters in Tartaric-Sulphuric Acid on Coating Thickness and Corrosion Resistance of Al 2024 T3 Alloy  [PDF]
Mohammad Zaki Mubarok, ? Wahab, ? Sutarno, Soleh Wahyudi
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2015, DOI: 10.4236/jmmce.2015.33018
Abstract: 2024 T3 is one of aluminium alloys which are widely used in the aircraft structures. Anodizing of alluminium alloy in tartaric-sulphuric acid (TSA) electrolyte is developed to obtain more environmentally-friendly process and to produce anodize layer with better corrosion resistance. In this research work, the influences of anodizing parameters of Al 2024 T3 in TSA on the thickness, weight and corrosion resistance of the anodize layer are studied. Corrosion resistance test was carried out by conducting salt spray test for 336 hours and anodic polarization measurements using potentiostat. Results of three-factor analysis of variance (ANOVA) demonstrated that the most influencing factor that determines the thickness and weight of the anodize layer is temperature, followed by applied voltage, duration of anodizing, voltage-temperature interaction, interaction of temperature-duration of anodizing, interaction of voltage-temperature-duration of anodizing, and interaction of voltage and duration of anodizing. The pit density and corrosion current density (icorr) were found to be dependent on the coating thickness. The anodize layer with a thickness of higher than 3 μm was not experienced to pitting corrosion during 336 hours of salt spray test.
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