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Sample records for corrosion denting

  1. Dent's disease

    Directory of Open Access Journals (Sweden)

    Thakker Rajesh V

    2010-10-01

    Full Text Available Abstract Dent's disease is a renal tubular disorder characterized by manifestations of proximal tubule dysfunction, including low-molecular-weight proteinuria, hypercalciuria, nephrolithiasis, nephrocalcinosis, and progressive renal failure. These features are generally found in males only, and may be present in early childhood, whereas female carriers may show a milder phenotype. Prevalence is unknown; the disorder has been reported in around 250 families to date. Complications such as rickets or osteomalacia may occur. The disease is caused by mutations in either the CLCN5 (Dent disease 1 or OCRL1 (Dent disease 2 genes that are located on chromosome Xp11.22 and Xq25, respectively. CLCN5 encodes the electrogenic Cl-/H+ exchanger ClC-5, which belongs to the CLC family of Cl- channels/transporters. OCRL1 encodes a phosphatidylinositol bisphosphate (PIP2 5-phosphatase and mutations are also associated with Lowe Syndrome. The phenotype of Dent's disease is explained by the predominant expression of ClC-5 in the proximal tubule segments of the kidney. No genotype-phenotype correlation has been described thus far, and there is considerable intra-familial variability in disease severity. A few patients with Dent's disease do not harbour mutations in CLCN5 and OCRL1, pointing to the involvement of other genes. Diagnosis is based on the presence of all three of the following criteria: low-molecular-weight proteinuria, hypercalciuria and at least one of the following: nephrocalcinosis, kidney stones, hematuria, hypophosphatemia or renal insufficiency. Molecular genetic testing confirms the diagnosis. The differential diagnosis includes other causes of generalized dysfunction of the proximal tubules (renal Fanconi syndrome, hereditary, acquired, or caused by exogenous substances. Antenatal diagnosis and pre-implantation genetic testing is not advised. The care of patients with Dent's disease is supportive, focusing on the treatment of hypercalciuria and

  2. Dens in Dente

    Directory of Open Access Journals (Sweden)

    Anita Balan

    2006-01-01

    Full Text Available Dens in dente are developmental malformation resulting from invagination of the crown before it is calcified. This anomaly is most frequently found in the permanent maxillary lateral incisor. Three cases, one of radicular and two of coronal dens in dente are reported.

  3. Corrosion

    Science.gov (United States)

    Slabaugh, W. H.

    1974-01-01

    Presents some materials for use in demonstration and experimentation of corrosion processes, including corrosion stimulation and inhibition. Indicates that basic concepts of electrochemistry, crystal structure, and kinetics can be extended to practical chemistry through corrosion explanation. (CC)

  4. Corrosion

    Science.gov (United States)

    Slabaugh, W. H.

    1974-01-01

    Presents some materials for use in demonstration and experimentation of corrosion processes, including corrosion stimulation and inhibition. Indicates that basic concepts of electrochemistry, crystal structure, and kinetics can be extended to practical chemistry through corrosion explanation. (CC)

  5. Facetas em dentes anteriores

    OpenAIRE

    Veloso, Helena Rafaela Lourenço Martins

    2015-01-01

    Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária A presente revisão bibliográfica aborda as facetas estéticas em dentes anteriores, pela crescente valorização de um sorriso esteticamente agradável, facto que faz com que as pessoas procurem cada vez mais alternativas de tratamento para melhorar a aparência do seu sorriso. Os dentes anteriores são decisivos na aparência estética e, c...

  6. Strategies and actions for the mitigation of the phenomenon DENTING in the tube sheet (TTS Denting) steam generators of the NPP Asco Denting at the top of the SG tube sheet (TTS tube denting) has recently been experienced in new and replacement SGs at several plants; Estrategias y acciones para la mitigacion del fenomeno DENTING en la placa tubular de generadores de vapor (TTS DENTING) de la Central Nuclear de Asco

    Energy Technology Data Exchange (ETDEWEB)

    Espanol Villar, J.

    2013-07-01

    It is highly likely that the accumulation of sludge (deposits) on the tube sheet is clearly associated with the denting occurrence. More specifically, it is commonly believed that an aggressive crevice environment formed within the deposits or in the shallow tight tube sheet to tube crevice below the deposits is at the origin of the denting (tube deformation), and, when present, the consequent stress corrosion cracking (SCC). There are described a set of strategies that have been followed since the emergence of the TTS denting phenomenon on Steam Generator of the Nuclear Power Plants Asco I and II, influenced by the presence of hard sludge in the tube plate of Steam Generators, their results and the evolution of the phenomenon in relation to the various measures taken.

  7. Study on the Effects of Environmental Parameters on High Temperature Denting Behavior in Crevices

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Myong Jin [University of Science and Technology, Daejeon (Korea, Republic of); Kim, Joung Soo; Kim, Dong Jin; Kim, Hong Pyo [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2011-10-15

    In the present study, denting corrosion experiments were performed as a function of crevice gap size (50, 100 and 200 {mu}m) in a solution containing 3,500 ppm NaCl + 0.2 M CuCl{sub 2} (pH = 3 adjusted by HCl). The effects of chloride ion concentrations (3, 3,500 and 35,000 ppm as NaCl) were also outlined with two different crevice gap sizes (100, 200 {mu}m). In addition, the effect of NiB on the denting corrosion was also investigated in a solution of 35,000 ppm NaCl + 0.2 M CuCl{sub 2} (pH = 3 adjusted by HCl). The results showed that denting rate increased with the increasing crevice gap size at an initial stage and became nearly constant afterwards. As the concentration of chloride ion increased, the denting rate also increased. However, the addition of a NiB powder of 4 g/L in to the acid-chloride solution was observed to suppress the denting rate significantly.

  8. Dens in dente of maxillary third molar

    Directory of Open Access Journals (Sweden)

    Subramaniam Arun

    2008-01-01

    Full Text Available ′Dens in dente,′ also known as dens invaginatus, is a developmental anomaly resulting from deepening or invagination of the enamel organ into the dental papilla, which begins at the crown and often extends to the root before calcification of the dental tissues. Dens in dente commonly occur in the maxillary lateral incisor. This article reports a case of dens in dente in the maxillary third molar.

  9. Undergraduate orthodontic & paediatric dentistry education in Europe--the DentEd project.

    Science.gov (United States)

    Harzer, W; Oliver, R; Chadwick, B; Paganelli, C

    2001-03-01

    As a result of a European Union funded project (DentEd), a programme of visits to dental schools throughout Europe has been underway since 1998. This report describes the philosophy behind DentEd, gives a brief description of the features of a visitation, and covers the orthodontic and paediatric dentistry teaching as reported in 26 different dental schools in 16 different countries. It is based on a report submitted to DentEd from a small working group that looked at various aspects of educational provision within the two disciplines across Europe. The value of this information to teachers within the two disciplines and to the wider dental community is briefly discussed. The report recommends the adoption of an integrated course for orthodontics and paediatric dentistry. The main objectives are that the student should be able to understand orofacial and psychosocial growth and development of the child, recognize aberrant growth and development, and manage the behaviour of the child, their straightforward preventive, restorative and occlusal needs, and to make appropriate and timely referral.

  10. Pulpotomia e pulpectomia em dentes decíduos

    OpenAIRE

    Costa, Soraya Lourenço

    2011-01-01

    Tese de mestrado, Medicna Dentária, Universidade de Lisboa, Faculdade de Medicina Dentária, 2011 As cáries dentárias na dentição decídua continuam a ser um importante problema de saúde. Quando a lesão se estende e envolve a polpa dentária, as técnicas de terapia pulpar são frequentemente utilizadas na abordagem de ambos os dentes, sintomáticos e assintomáticos. Tanto a pulpotomia como a pulpectomia são, em algumas situações, alternativas apropriadas à extracção dos dentes decíduos, retendo...

  11. Premolarized double dens in dente in albinism - A case report

    Directory of Open Access Journals (Sweden)

    Suprabha B

    2005-09-01

    Full Text Available Dens in dente are known to be associated with many dental abnormalities such as taurodontism microdontia, gemination, and dens evaginatus. This paper describes a rare case of double dens in dente in a lateral incisor with crown morphology similar to a premolar present in a patient with features of albinism. Problems associated with this condition and their management is discussed.

  12. Exercise Not Making Dent in Most Seniors' Down Time

    Science.gov (United States)

    ... page: https://medlineplus.gov/news/fullstory_167481.html Exercise Not Making Dent in Most Seniors' Down Time ... 2017 FRIDAY, July 28, 2017 (HealthDay News) -- Regular exercise does little to reduce the amount of time ...

  13. Reabsorção dentária

    OpenAIRE

    Koval, Anna

    2015-01-01

    Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária Este trabalho científico no âmbito de conclusão do curso de Mestrado Integrado em Medicina Dentária na Universidade Fernando Pessoa teve como principal objetivo, a realização de uma revisão bibliográfica acerca de reabsorções dentárias. Os objetivos particulares foram: classificar na sua generalidade as reabsorções dentárias, analisa...

  14. Cisto dentígero: modalidades de tratamento

    Directory of Open Access Journals (Sweden)

    Rubens Caliento

    Full Text Available INTRODUÇÃO: O cisto dentígero é o segundo cisto odontogênico mais frequente nos maxilares. É uma lesão benigna, derivada do epitélio odontogênico da coroa de um dente não erupcionado, porém de etiopatogenia incerta. São geralmente radiotransparentes e, mais comumente, uniloculares. Estas lesões são observadas em exames de rotina ou quando não ocorre o irrompimento de um dente permanente. Os terceiros molares inferiores e os caninos superiores são os dentes mais acometidos, sendo também alta a ocorrência desta lesão em dentes supranumerários e associados a odontomas. O cisto dentígero ocorre principalmente nas três primeiras décadas de vida, tendo um crescimento lento e assintomático; pode atingir dimensões consideráveis, causando deformidade facial, impactação e deslocamento de dentes e/ou estruturas adjacentes. OBJETIVO: Definição das técnicas de marsupialização e enucleação, bem como consideração de critérios objetivos importantes para o plano de tratamento, como tamanho do cisto, idade, proximidade com estruturas anatômicas e importância clínica do dente envolvido. Apesar das peculiaridades clínicas de cada caso e do método de tratamento escolhido, o prognóstico destas lesões é favorável, quando se emprega apropriada terapêutica. MATERIAL E MÉTODO: O presente estudo apresentará um relato de caso tratado através da manobra de descompressão seguida de enucleação, bem como uma discussão acerca das modalidades de tratamento. RESULTADO: O paciente encontra-se em pós-operatório de dois anos sem sinais de recidiva da lesão e ausência de parestesias em face. CONCLUSÃO: A técnica empregada preservou a função neurossensorial e mostrou-se eficiente para a cura da lesão.

  15. Quiste dentígero en niños

    OpenAIRE

    Fernanda Astrogilda de Sousa Feitosa; Amanda Simião Figueiredo; Carolina Carvalho de Oliveira Santos; Bertha Angélica Chávez Gonzalez; Raquel Gonçalves Vieira-Andrade; Thiago Fonseca-Silva

    2016-01-01

    Introducción: El quiste dentígero es el segundo tipo de quistes odontogénicos más frecuentes de los maxilares, desarrollándose a partir de alteraciones del epitelio del órgano del esmalte, donde ocurre una acumulación de líquido entre el epitelio y el esmalte. Por lo general está relacionado a la corona de un diente no erupcionado. Objetivos: el objetivo de este estudio fue analizar los aspectos de diagnóstico y tratamiento de los quistes dentígero en pacientes pediátricos. Métodos: se realiz...

  16. Testing of DentStat (trademark) and Competing Dental Materials

    Science.gov (United States)

    2014-06-13

    15 3 Executive Summary Background: Glass ionomers (GI) were developed for use as...acid). Glass ionomers were later modified with the addition of a light-polymerized liquid resin component that allows the provider to photocure the...cement. Recently the US Navy developed a new resin modified glass ionomer (RMGI), DentStat™, to be utilized in emergency situations to temporarily

  17. Analysis Of Dynamic Dent Resistance Of Auto Body Panel

    Science.gov (United States)

    Deolgaonkar, S. S.; Nandedkar, V. M.

    2007-04-01

    In automotive industry there is increasing demand for higher quality exterior panels, better functional properties and lower weight. The demand for weight reduction has led to thinner sheets, greater use of high strength steels and a change from steel to aluminum grades. This thickness reduction, which causes decrease in the dent resistance, promoted examination of the dent resistance against static and dynamic concentrated loads. This paper describes an investigation of the suitability of explicit dynamic FE analysis as a mean to determine the dynamic dent properties of the panel. This investigation is carried out on the body panel of utility vehicle and covers two parts, in first experimental analysis is carried out on developed test rig, which is interfaced with the computer. This test rig measures deflection with accuracy of .001mm. The experimental results are then compared with the simulation results, which is the second part. Simulation is carried with non-linear transient dynamic explicit analysis using Ansys -Ls Dyna. The experimental results show great accuracy with simulation results. The effect of change in thickness and geometry of the existing fender is then studied with help of simulation technique. By considering the best possible option overall weight of fender is reduced by 7.07 % by keeping the dent resistance of the panel constant.

  18. Quiste dentígero en niños

    Directory of Open Access Journals (Sweden)

    Fernanda Astrogilda de Sousa Feitosa

    2016-01-01

    Full Text Available Introducción: El quiste dentígero es el segundo tipo de quistes odontogénicos más frecuentes de los maxilares, desarrollándose a partir de alteraciones del epitelio del órgano del esmalte, donde ocurre una acumulación de líquido entre el epitelio y el esmalte. Por lo general está relacionado a la corona de un diente no erupcionado. Objetivos: el objetivo de este estudio fue analizar los aspectos de diagnóstico y tratamiento de los quistes dentígero en pacientes pediátricos. Métodos: se realizó una búsqueda de artículos científicos indexados en la base de datos bibliográficos PUBMED® en el período comprendido entre febrero y marzo de 2015, mediante el descriptor "dentigerous cyst". Resultados: Se encontraron 147 artículos publicados en los últimos 10 años. Todos los artículos que trataban sobre quiste dentígero en niños fueron incluidos en este estudio. La literatura revisada destaca puntos importantes sobre la epidemiología, manejo y tratamiento de quiste dentígero en pacientes pediátricos. Conclusión: De los artículos revisados se puede concluir que el quiste dentígero es más frecuente en los niños del género masculino y con una edad media de 10 años. Afecta principalmente a la mandíbula y tanto la enucleación como la marsupialización están indicados para el tratamiento de quistes

  19. Corrosion protection

    Science.gov (United States)

    Brown, Donald W.; Wagh, Arun S.

    2003-05-27

    There has been invented a chemically bonded phosphate corrosion protection material and process for application of the corrosion protection material for corrosion prevention. A slurry of iron oxide and phosphoric acid is used to contact a warm surface of iron, steel or other metal to be treated. In the presence of ferrous ions from the iron, steel or other metal, the slurry reacts to form iron phosphates which form grains chemically bonded onto the surface of the steel.

  20. Corrosion Engineering.

    Science.gov (United States)

    White, Charles V.

    A description is provided for a Corrosion and Corrosion Control course offered in the Continuing Engineering Education Program at the General Motors Institute (GMI). GMI is a small cooperative engineering school of approximately 2,000 students who alternate between six-week periods of academic study and six weeks of related work experience in…

  1. Corrosion sensor

    Science.gov (United States)

    Glass, Robert S.; Clarke, Jr., Willis L.; Ciarlo, Dino R.

    1994-01-01

    A corrosion sensor array incorporating individual elements for measuring various elements and ions, such as chloride, sulfide, copper, hydrogen (pH), etc. and elements for evaluating the instantaneous corrosion properties of structural materials. The exact combination and number of elements measured or monitored would depend upon the environmental conditions and materials used which are subject to corrosive effects. Such a corrosion monitoring system embedded in or mounted on a structure exposed to the environment would serve as an early warning system for the onset of severe corrosion problems for the structure, thus providing a safety factor as well as economic factors. The sensor array is accessed to an electronics/computational system, which provides a means for data collection and analysis.

  2. Bullet dents – “Proof marks” or battle damage

    Directory of Open Access Journals (Sweden)

    Williams, Alan

    2006-12-01

    Full Text Available

    It is well known that the breastplates of many armours from the later 16th century and the 17th century bear the hemispherical dents generally known as proof marks. It has been taken as axiomatic that these marks were made in order to demonstrate the armours’ effectiveness against firearms. If however some of these dents are compared with dents which are the result of battle damage, it appears that they were made by energy levels of a different order of magnitude, and offer little guarantee as to the “proof” of the armour.



    Como es bien sabido, muchos petos de armaduras de finales del siglo XVI y del XVII tienen abolladuras semiesféricas conocidas como pruebas de arcabuz. Se ha considerado axiomático que estas abolladuras fueron hechas para demostrar la efectividad de las armaduras frente a las armas de fuego. Sin embargo, si se comparan con otras debidas a daños en combate, parece que fueron producidas por energías de diferente orden o magnitud, al tiempo que ofrecen pocas garantías como “pruebas” de las armaduras.

  3. Fractura da cortical alveolar resultante da exodontia de dentes anquilosados

    OpenAIRE

    2010-01-01

    Monografia apresentada à Universidade Fernando Pessoa para obtenção do grau Licenciado em Medicina Dentária A anquilose dento-alveolar constitui uma condição patológica que consiste na fusão anatómica entre o cemento radicular e o osso alveolar propriamente dito, podendo ocorrer durante qualquer etapa do processo eruptivo. Os factores etiológicos da anquilose dento-alveolar ainda não estão totalmente esclarecidos, existindo diversas teorias que pretendem explicar o fenómeno. O objectivo...

  4. Reduction transport of corrosion products through the secondary circuit by increasing the dosage of ammonia; Reduccion del transporte de productos de corrosion a traves del circuito secundario mediante el aumento de la dosificacion de amoniaco

    Energy Technology Data Exchange (ETDEWEB)

    Espanol, J.; Boronat, M.

    2015-07-01

    Reduce transport of corrosion products through the Secondary Circuit, mainly magnetite, by increasing the dosage of ammonia in order to reduce oxides accumulation in the Steam Generators top of tube sheet where become hard sludge, as one of the TTS denting mitigation actions. (Author)

  5. Progress on Dent's disease%Dent病研究进展

    Institute of Scientific and Technical Information of China (English)

    刘妍

    2012-01-01

    There are many causes of proteinuria in children.Because proteinuria is mainly caused by glomerular diseases,renal tubulopathies are often ignored.Dent's disease is an hereditary renal tubulopathy characterized by low-molecular-weigh proteinuria,hypercalciuria,nephrocalcinosis,nephrolithiasis,and progressive renal failure.Dent's disease is mainly caused by mutations in CLCN5 and OCRL1 genes.Current treatments of the disease are still mainly symptomatic and supportive therapy,including reducing urinary calcium excretion,lightening nephrocalcinosis,and delaying the occurrence of renal insufficiency.%小儿蛋白尿的原因很多,多数是由于肾小球疾病引起,故往往忽略了肾小管疾病致蛋白尿的出现.Dent病为一种遗传性肾小管疾病,主要表现为低相对分子原量蛋白尿、高钙尿症、肾脏钙化、肾石症及进行性肾衰竭.目前主要发现CLCN5基因和OCRL1基因突变可导致Dent病的发生.Dent病的治疗目前仍以对症支持治疗为主,主要是降低尿钙排泄,减轻肾脏钙化以及延缓肾功能不全的发生.

  6. Corrosion in airframes

    OpenAIRE

    PETROVIC ZORAN C.

    2016-01-01

    The introductory chapter provides a brief reference to the issue of corrosion and corrosion damage to aircraft structures. Depending on the nature and dimensions of this non uniformity, three different categories of corrosion are defined: uniform, selective and localized corrosion. The following chapters present the forms of corrosion that can occur in three defined categories of corrosion. Conditions that cause certain types of corrosion in various corrosive environments are discussed. Examp...

  7. CORROSION IN AIRFRAMES

    OpenAIRE

    PETROVIC ZORAN C.

    2016-01-01

    The introductory chapter provides a brief reference to the issue of corrosion and corrosion damage to aircraft structures. Depending on the nature and dimensions of this non uniformity, three different categories of corrosion are defined: uniform, selective and localized corrosion. The following chapters present the forms of corrosion that can occur in three defined categories of corrosion. Conditions that cause certain types of corrosion in various corrosive environments are discussed. Examp...

  8. A radiologia dentária na gravidez

    OpenAIRE

    Silva, José Oliveira da

    2013-01-01

    Aborda-se a biossegurança aplicada a radiologia dentária relativa à radiação ionizante e a exposição aos agentes biológicos, a que pacientes, grávidas / feto e profissionais são submetidos durante os procedimentos radiológicos. As diferentes doses de radiação emitidas, pelos equipamentos utilizados em radiologia oral, quer nos sistemas analógicos, como digitais. As diversas formas de propagação de micro-organismos, durante a obtenção de imagens radiográficas. As medidas de biossegurança, para...

  9. A radiologia dentária na gravidez

    OpenAIRE

    Silva, José Oliveira da

    2013-01-01

    Aborda-se a biossegurança aplicada a radiologia dentária relativa à radiação ionizante e a exposição aos agentes biológicos, a que pacientes, grávidas / feto e profissionais são submetidos durante os procedimentos radiológicos. As diferentes doses de radiação emitidas, pelos equipamentos utilizados em radiologia oral, quer nos sistemas analógicos, como digitais. As diversas formas de propagação de micro-organismos, durante a obtenção de imagens radiográficas. As medidas de biossegurança, para...

  10. Underground pipeline corrosion

    CERN Document Server

    Orazem, Mark

    2014-01-01

    Underground pipelines transporting liquid petroleum products and natural gas are critical components of civil infrastructure, making corrosion prevention an essential part of asset-protection strategy. Underground Pipeline Corrosion provides a basic understanding of the problems associated with corrosion detection and mitigation, and of the state of the art in corrosion prevention. The topics covered in part one include: basic principles for corrosion in underground pipelines, AC-induced corrosion of underground pipelines, significance of corrosion in onshore oil and gas pipelines, n

  11. Ultimate strength performance of tankers associated with industry corrosion addition practices

    Science.gov (United States)

    Kim, Do Kyun; Kim, Han Byul; Zhang, Xiaoming; Li, Chen Guang; Paik, Jeom Kee

    2014-09-01

    In the ship and offshore structure design, age-related problems such as corrosion damage, local denting, and fatigue damage are important factors to be considered in building a reliable structure as they have a significant influence on the residual structural capacity. In shipping, corrosion addition methods are widely adopted in structural design to prevent structural capacity degradation. The present study focuses on the historical trend of corrosion addition rules for ship structural design and investigates their effects on the ultimate strength performance such as hull girder and stiffened panel of double hull oil tankers. Three types of rules based on corrosion addition models, namely historic corrosion rules (pre-CSR), Common Structural Rules (CSR), and harmonised Common Structural Rules (CSRH) are considered and compared with two other corrosion models namely UGS model, suggested by the Union of Greek Shipowners (UGS), and Time-Dependent Corrosion Wastage Model (TDCWM). To identify the general trend in the effects of corrosion damage on the ultimate longitudinal strength performance, the corrosion addition rules are applied to four representative sizes of double hull oil tankers namely Panamax, Aframax, Suezmax, and VLCC. The results are helpful in understanding the trend of corrosion additions for tanker structures

  12. Experimental evaluation of residual stresses produced by plain dents in pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Pascotto, Jorge [PETROBRAS Transporte S.A. (TRANSPETRO), Rio de Janeiro, RJ (Brazil); Marques, Altino; Fonseca, Maria Cindra [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil)

    2009-07-01

    A dent means a permanent plastic deformation of the circular cross-section of the pipe. Dents are potentially danger for structural integrity of onshore and offshore pipelines, because it causes a local stress and strain concentration. It is also expected that residual stresses are introduced by the non-uniform plastic deformation. A plain dent is a dent which causes a smooth change in the curvature of the pipe wall that contains no wall thickness reductions (such as a gouge or a crack) or other defects or imperfections (such as a weld). This work presents an experimental evaluation of residual stresses intensification due to plain dents introduced through the same indentation process, in samples made of the same steel line pipe, commonly used in the pipeline industry. The residual stresses were measured in the longitudinal and circumferential directions in preselected points by X-ray diffraction technique, before indentation. After the samples have been dented, the residual stresses were measured once more at the same points, for comparison. All samples presented a similar behavior of the residual stresses due to induced plain dents, and the X-ray diffraction technique shows itself as an efficient methodology of stress measurement in pipelines. (author)

  13. Stress corrosion cracking of alloy 600 using the constant strain rate test

    Energy Technology Data Exchange (ETDEWEB)

    Bulischeck, T. S.; van Rooyen, D.

    1980-01-01

    The most recent corrosion problems experienced in nuclear steam generators tubed with Inconel alloy 600 is a phenomenon labeled ''denting''. Denting has been found in various degrees of severity in many operating pressurized water reactors. Laboratory investigations have shown that Inconel 600 exhibits intergranular SCC when subjected to high stresses and exposed to deoxygenated water at elevated temperatures. A research project was initiated at Brookhaven National Laboratory in an attempt to improve the qualitative and quantitative understanding of factors influencing SCC in high temperature service-related environments. An effort is also being made to develop an accelerated test method which could be used to predict the service life of tubes which have been deformed or are actively denting. Several heats of commercial Inconel 600 tubing were procured for testing in deaerated pure and primary water at temperatures from 290 to 365/sup 0/C. U-bend type specimens were used to determine crack initiation times which may be expected for tubes where denting has occurred but is arrested and provide baseline data for judging the accelerating effects of the slow strain rate method. Constant extension rate tests were employed to determine the crack velocities experienced in the crack propagation stage and predict failure times of tubes which are actively denting. 8 refs., 17 figs., 5 tabs.

  14. Luxações intrusivas em dentes decíduos e permanentes jovens

    OpenAIRE

    Lopes, Célia Gabriela da Silva

    2009-01-01

    Monografia apresentada à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Licenciada em Medicina Dentária Este trabalho científico foi realizado no âmbito da conclusão do curso de Licenciatura em Medicina Dentária na Universidade Fernando Pessoa e teve como principal objectivo, a realização de uma revisão bibliográfica acerca das luxações intrusivas em dentes decíduos e permanentes jovens. Os objectivos particulares foram: classificar na sua gener...

  15. Corrosion Testing Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Corrosion Testing Facility is part of the Army Corrosion Office (ACO). It is a fully functional atmospheric exposure site, called the Corrosion Instrumented Test...

  16. Prevalência de dentes supranumerários na consulta de odontopediatria da Clínica Dentária Universitária Egas Moniz

    OpenAIRE

    Coimbra, Filipe Simplício Brinca Glória

    2016-01-01

    Dissertação para obtenção do grau de Mestre no Instituto Superior de Ciências da Saúde Egas Moniz Objetivo: Avaliar a prevalência de dentes supranumerários numa determinada população pediátrica da Clínica Dentária Universitária Egas Moniz, através da análise de Ortopantomografias e História Clínicas. Métodos: Foram examinadas Ortopantomografias e Histórias Clínicas de 100 indivíduos com idades compreendidas entre os 6 e os 18 anos para o estudo epidemiológico sobre a ocorrência de dente...

  17. A comparison of some methods to estimate the fatigue life of plain dents

    Energy Technology Data Exchange (ETDEWEB)

    Martins, Ricardo R.; Noronha Junior, Dauro B. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)

    2009-12-19

    This paper describes a method under development at PETROBRAS R and D Center (CENPES) to estimate the fatigue life of plain dents. This method uses the API Publication 1156 as a base to estimate the fatigue life of dome shaped plain dents and the Pipeline Defect Assessment Manual (PDAM) approach to take into account the uncertainty inherent in the fatigue phenomenon. CENPES method, an empirical and a semi-empirical method available in the literature were employed to estimate the fatigue lives of 10 plain dents specimens of Year 1 of an ongoing test program carried out by BMT Fleet Technology Limited, with the support of the Pipeline Research Council International (PRCI). The results obtained with the different methods are presented and compared. Furthermore some details are given on the numerical methodology proposed by PETROBRAS that have been used to describe the behavior of plain dents. (author)

  18. Conservative Management of Type III Dens in Dente Using Cone Beam Computed Tomography

    National Research Council Canada - National Science Library

    K Pradeep; M Charlie; M Kuttappa; Prasana Rao

    2012-01-01

      Dens in dente, also known as dens invaginatus, dilated composite odontoma, or deep foramen caecum, is a developmental malformation that usually affects maxillary incisor teeth, particularly lateral incisors...

  19. Investigation of Highly Designable Dented Structures in HP Model with Hydrogen Bond Energy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei; HUANG Shengyou; YU Tao; ZOU Xianwu

    2007-01-01

    Some highly designable protein structures have dented on the surface of their native structures, and are not full compactly folded. According to hydrophobic-polar (HP) model the most designable structures are full compactly folded. To investigate the designability of the dented structures, we introduce the hydrogen bond energy in the secondary structures by using the secondary-structure-favored HP model proposed by Ou-yang etc. The result shows that the average designability increases with the strength of the hydrogen bond. The designabilities of the structures with same dented shape increase exponentially with the number of secondary structure sites. The dented structures can have the highest designabilities for a certain value of hydrogen bond energy density.

  20. Traumatismo dentário em dentição permanente jovem

    OpenAIRE

    2014-01-01

    Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária Introdução: Estudos epidemiológicos indicam que o traumatismo dentário é um problema significativo em jovens 8-15 anos e que a sua incidência em determinadas faixas etárias pode ultrapassa o da cárie dentária e da doença periodontal. Deste modo, o traumatismo dentário é sinónimo de um problema de saude pública em que o seu aumento se...

  1. A relevância do apertamento dentário nas desordens temporomandibulares

    OpenAIRE

    Cardoso, Lorena Marcelino; Kraychete,Durval Campos; Araújo,Roberto Paulo Correia de

    2011-01-01

    p.277-283 Hábitos parafuncionais como o ranger de dentes e o apertamento dentário são um achado comum e de grande relevância nos consultórios odontológicos. O estresse mecânico gerado por tais hábitos favorece a fratura de dentes e restaurações, perda de próteses e implantes, danos às estruturas de suporte, ou mesmo, exacerbação de desordens temporomandibulares (DTMs) e desencadeamento de dor. O apertamento dentário é um hábito parafuncional cuja origem é considerada de natureza m...

  2. Classificação morfofuncional dos dentes de quati, Nasua nasua

    Directory of Open Access Journals (Sweden)

    Naira C.G Pieri

    2011-05-01

    Full Text Available O quati (Nasua nasua, é um mamífero onívoro, amplamente distribuído pela América do sul e encontrado em todo Brasil. A evolução provocou nos dentes dos mamíferos múltiplas variações, adequando às mais diversas dietas. Por essas variações nos dentes é possível classificar os vertebrados em ordem, gênero e família. Portanto este trabalho teve como objetivo descrever e classificar morfologicamente os dentes de machos e fêmeas de N. nausa, a fim de classificá-los e compará-los entre si e com a morfologia dos dentes de Canis familiaris descrita na literatura. Neste estudo foram utilizados cinco animais Nasua nasua, adultos, de ambos os sexos, cedidas pelo Criatório Cientifico Cecrimpas (Unifeob. Dois deles macerados tiveram a cavidade oral exposta para a realização da documentação fotográfica da posição dos dentes, outros três, os dentes foram submetidos à descalcificação e processamento e embebição em parafina para observação histológica. Na cavidade oral de N. nasua, devido ao dimorfismo sexual, foi possível comparar a dentição do macho e da fêmea macroscopicamente. A fêmea apresentou dentes menores, caninos arredondados e o macho, caninos maiores. Os animais apresentaram a fórmula dentária 2x(I3/3, C1/1, P4/4, M2/2 (I=incisivos, C=caninos, P=pré-molares e M=molares = 40. Microscopicamente todos os dentes foram classificados como braquidontes, pois o esmalte é depositado sobre a dentina. Este tipo de dente não tem erupção constante como o hipsodonte, pois seu esmalte permanece intacto até a época de erupção. Seus dentes também foram classificados como anelodontes, por ter um período limitado de características de crescimento.

  3. Shear Bond Strength of DentStat(trademark) for Bracket Bonding to Gold, Ceramic, and Enamel

    Science.gov (United States)

    2012-12-21

    i Shear bond strength of DentStatTM for bracket bonding to gold, ceramic, and enamel . A THESIS Presented to the Faculty of Uniform...in the thesis manuscript entitled: ’Shear Bond Strength of DentStatTM for Bracket Bonding to Gold, Ceramic, and Enamel ’ is appropriately...Ceramic, and Enamel ’ 7. Intended publication/meeting: June 2013 8. "Required by" date: 1 July 2013 9. Date of submission for USU approval: 6 June

  4. The use of B-splines in the assessment of strain levels associated with plain dents

    Energy Technology Data Exchange (ETDEWEB)

    Noronha Junior, Dauro B.; Martins, Ricardo R. [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES); Jacob, Breno P.; Souza, Eduardo [Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenharia Civil. Lab. de Metodos Computacionais e Sistemas Offshore (LAMCSO)

    2005-07-01

    Most international pipeline codes consider plain dents injurious if they exceed a depth of 6% of the nominal pipe diameter. ASME B31.8 - Gas Transmission and Distribution Piping Systems - 2003 Edition gives an alternative to the above mentioned limit. According to this edition of the code, plain dents of any depth are acceptable provided strain levels associated with the deformation do not exceed 6% strain. In order to use the method for estimating strain in dents proposed in Appendix R of B31.8 Code, interpolation or other mathematical technique is usually necessary to develop surface contour information from in-line inspections (ILI) tools or direct information data. This paper describes the application of a piece-wise interpolating technique that makes use of fourth-order B-spline curves to approximating the dent profile in both longitudinal and circumferential directions. The results obtained using B-splines were tested against nonlinear finite analyses of dented pipelines and a distinct methodology proposed by Rosenfeld et al. (1998). The results obtained with the use of B-splines compared well with both techniques. Furthermore, the extension of the proposed methodology to the description of the topology of dents with more general shapes using B-spline surfaces is very promising. (author)

  5. Aircraft Corrosion

    Science.gov (United States)

    1981-08-01

    allowed to dry. The area is then checked for the golden brown color which is produced by the chemical conversion material. If the work area requires...Materials, pp. 258-3074 1968. 41. W. IH. Ailor, "Seven-year exposure at Point leyes , California," "Corrosion in Natural Environments, ASTM STP 558," American... Color Units 3 Turbidity Units 0.7 pH Units 7.6 Temperature OF 76 Sp. Conductivity MMhos 425 B.O.D. (5 days at 206C) 0.2 SjV i;~-- 1201 A .9 8 ~ 8 kl

  6. ESTUDO DA DISTRIBUIÇÃO DAS TENSÕES INTERNAS, SOB CARGA AXIAL, EM DENTE HÍGIDO E EM DENTE RESTAURADO COM COROA METALOCERÂMICA E RETENTOR INTRA-RADICULAR FUNDIDO: - MÉTODO DO ELEMENTO FINITO

    OpenAIRE

    Matsuyoshi MORI; UETI,Mario; MATSON,Edmir; Saito, Tetsuo

    1997-01-01

    Estudou-se comparativamente, pelo método do elemento finito em modelo bidimensional de segundo pré-molar inferior, a distribuição de tensões internas, geradas sob carga axial de 30 kgf em três pontos (contatos principal e estabilizante), em dente natural hígido e em dente endodonticamente tratado. O programa utilizado para o processamento do elemento finito foi o SAP90. Os resultados indicaram maior acúmulo de tensões na metade vestibular, tanto no dente hígido quanto no dente restaurado. As ...

  7. Portable laserscan for in-ditch dent profiling and strain analysis: methodology and application development

    Energy Technology Data Exchange (ETDEWEB)

    Arumugam, Udayasankar; Tandon, Samarth; Gao, Ming; Krishnamurthy, Ravi [Blade Energy Partners, Houston, Texas (United States); Hanson, Ben; Rehman, Hamood; Fingerhut, Martin [Applus RTD, Houston, Texas (United States)

    2010-07-01

    Mechanical damage to pipelines has been assessed with two methodologies. The traditional one was a depth-based assessment, whose limitations could result in an underestimation of the dent severity. In more recent years, therefore, operators have preferred to complement this method with the use of strain-based criteria. The data from an ILI caliper tool can be used to calculate strain in order to determine dent severity. After every ILI run, verification of inspection performance is necessary, but this has been a challenge for the industry because of the lack of a unified protocol and other causes. According to a recent study, LaserScan 3D technology provides an accurate profile and is an ideal tool for verification of ILI performance. This paper introduces a portable LaserScan 3D mapping technology to measure dents, alone or associated with other anomalies. It discusses the accuracy and resolution of this technology and its appropriateness for pipelines.

  8. A novel CLCN5 mutation in a Chinese boy with Dent's disease

    Institute of Scientific and Technical Information of China (English)

    Li-Na Ji; Chao-Ying Chen; Jing-Jing Wang; Li Cao

    2014-01-01

    Background: Dent's disease is a rare X-linked recessive hereditary disease caused by mutations in either the CLCN5 or OCRL1 genes. This disease is characterized by manifestations of proximal renal tubule dysfunction associated with low molecular weight proteinuria (LMWP), hypercalciuria, nephrocalcinosis, nephrolithiasis, and progressive renal failure. Methods: We report a Chinese boy with Dent's disease, clinically diagnosed by LMWP and hypercalciuria. Genetic analysis was made of the CLCN5 and OCRL1 genes. Related studies were also reviewed. Results: A splice site mutation IVS6, +2T>C of the CLCN5 gene was revealed in this case, and it was not reported previously. Conclusions: Clinical and genetic analysis is valuable for the diagnosis of Dent's disease. A novel mutation in the CLCN5 gene was identifi ed in our patient.

  9. Avaliação de dentes decíduos e permanentes traumatizados

    OpenAIRE

    Macari, Karina Silva Moreira [UNESP

    2004-01-01

    É alta a incidência de traumatismos dentários principalmente nas crianças e nos adolescentes, sendo freqüente a ocorrência de complicações em decorrência destes traumas. Assim, realizou-se um estudo clínico e radiográfico de dentes anteriores decíduos e permane ntes traumatizados e também de dentes sucessores a decíduos traumatizados de crianças atendidas na Faculdade de Odontologia de Araçatuba - UNESP e na Fundação Educacional de Barretos - FEB, analisando a ocorrência de seqüelas e os fato...

  10. Conservative Management of Type III Dens in Dente Using Cone Beam Computed Tomography

    Directory of Open Access Journals (Sweden)

    K Pradeep

    2012-01-01

    Full Text Available Dens in dente, also known as dens invaginatus, dilated composite odontoma, or deep foramen caecum, is a developmental malformation that usually affects maxillary incisor teeth, particularly lateral incisors. It may occur in teeth anywhere within the jaws, other locations are comparatively rare. It can occur within both the crown and the root, although crown invaginations are more common. The use of cone beam computed tomography (CBCT is very helpful in endodontic diagnosis of complex anatomic variations. In this case we demonstrate the use of CBCT in the evaluation and endodontic management of a Type III dens in dente (Oehler′s Type III.

  11. "Traumatismos alvéolo-dentários: estudo de uma amostra hospitalar"

    OpenAIRE

    2004-01-01

    A quantidade de trabalhos específicos sobre os traumatismos alvéolo-dentários de maior extensão encontrados na literatura é pequena. Este estudo mostra o resultado de 127 casos de traumatismos alvéolo-dentários diagnosticados no Hospital Municipal Arthur Ribeiro de Saboya, em São Paulo, entre junho de 2001 e dezembro de 2002. A análise dos dados permitiu identificar o grupo etário de 0 a 10 anos e o sexo masculino como os mais atingidos, a queda como o fator etiológico mais comum e a fratura ...

  12. Modelling of Corrosion Cracks

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    Modelling of corrosion cracking of reinforced concrete structures is complicated as a great number of uncertain factors are involved. To get a reliable modelling a physical and mechanical understanding of the process behind corrosion in needed.......Modelling of corrosion cracking of reinforced concrete structures is complicated as a great number of uncertain factors are involved. To get a reliable modelling a physical and mechanical understanding of the process behind corrosion in needed....

  13. Fast and low budget automated body armour plastilina dent measurement by a low cost structured light scanner

    NARCIS (Netherlands)

    Philippens, M.A.G.; Renswoude, K. van; Schie, K. van

    2014-01-01

    Depth, diameter and volume of dents in clay backing of soft and hard body armour are used to assess the protective performance of such vests. The characteristics of the dents are traditionally measured manually. Optical scan techniques are becoming more popular and provide an objective method compar

  14. Management of Reinforcement Corrosion

    DEFF Research Database (Denmark)

    Küter, André; Geiker, Mette Rica; Møller, Per

    Reinforcement corrosion is the most important cause for deterioration of reinforced concrete structures, both with regard to costs and consequences. Thermodynamically consistent descriptions of corrosion mechanisms are expected to allow the development of innovative concepts for the management...... of reinforcement corrosion....

  15. Corrosion inhibitors; Los inhibidores de corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Godinez, L. A.; Meas, Y.; Ortega-Borges, R.; Corona, A.

    2003-07-01

    In this paper, we briefly describe the characteristics, cost and electrochemical nature of the corrosion phenomena as well as some of the technologies that are currently employed to minimize its effect. The main subject of the paper however, deals with the description, classification and mechanism of protection of the so-called corrosion inhibitors. Examples of the use of these substances in different aggressive environments are also presented as means to show that these compounds, or their combination, can in fact be used as excellent and relatively cheap technologies to control the corrosion of some metals. In the last part of the paper, the most commonly used techniques to evaluate the efficiency and performance of corrosion inhibitors are presented as well as some criteria to make a careful and proper selection of a corrosion inhibitor technology in a given situation. (Author) 151 refs.

  16. Finite element analysis of stiffness and static dent resistance of aluminum alloy double-curved panel in viscous pressure forming

    Institute of Scientific and Technical Information of China (English)

    LI Yi; WANG Zhong-Jin

    2009-01-01

    The static dent resistance performance of the aluminum alloy double-curved panel formed using viscous pressure forming (VPF) was studied by finite element analysis, which mainly considers the forming process conditions. The whole simulation consisting of three stages, i.e., forming, spring-back and static dent resistance, was carried out continuously using the finite element code ANSYS. The influence of blank holder pressure (BHP) and the drawbead on the stiffness and the static dent resistance of the panels formed using VPF was analyzed. The results show that the adequate setting of the drawbead can increase the plastic deformation of the double-curved panel, which is beneficial to the initial stiffness and the static dent resistance. There is an optimum BHP range for the stiffness and the static dent resistance.

  17. Periodontal conditions of teeth presenting pathologic migration Condições periodontais de dentes com migração dentária patológica

    Directory of Open Access Journals (Sweden)

    Maurício Ribeiro Costa

    2004-12-01

    Full Text Available The aim of the present study was to evaluate the periodontal conditions of anterior teeth that presented pathologic migration in patients with chronic periodontitis and to compare periodontal destruction in migrated versus non-migrated teeth. The sample included 32 patients of both sexes (mean age: 46.0 ± 11.6 years diagnosed with generalized chronic periodontitis and selected on the basis of the presence of pathologic migration in one or more anterior teeth. This migration was classified according to the following categories: facial flaring, diastema, proximal tilting, rotation or extrusion. The periodontal parameters recorded were clinical attachment loss (CAL and percentage of radiographic bone loss (BL. Mean CAL of 5.50 ± 2.20 mm and mean BL of 41.90 ± 15.40% were found in 115 teeth assessed. The most frequent type of migration was facial flaring (34.80%, followed by diastema (27.00%. Extrusion was hardly observed in the sample (4.30%. However, greater severity of BL and CAL were observed in teeth with this type of migration (59.44% and 8.42 mm, respectively, and in teeth with facial flaring (45.17% of BL and 6.07 mm of CAL. Kruskal-Wallis test indicated that BL presented by teeth with extrusion or facial flaring was greater than that observed in rotated or tilted teeth (p O objetivo deste estudo foi avaliar as condições clínicas periodontais de dentes anteriores com migração patológica (MDP em pacientes com periodontite crônica generalizada e comparar a severidade de destruição periodontal entre dentes migrados e não-migrados. Foram selecionados 32 pacientes, de ambos os sexos, apresentando média de idade de 46,0 anos (± 11,6, com perda clínica de inserção em dentes anteriores e presença de algum tipo de MDP, a saber: vestibularização, diastema, inclinação proximal, giroversão ou extrusão. Os parâmetros avaliados foram a perda clínica de inserção (PIC e o percentual de perda óssea radiográfica (PO. Os

  18. Residual dent in locally loaded foam core sandwich structures – Analysis and use for NDI

    NARCIS (Netherlands)

    Koysin, V.; Shipsha, Andrey

    2008-01-01

    This paper addresses the residual denting in the face sheet and corresponding core damage in a locally loaded flat sandwich structure with foam core. The problem is analytically considered in the context of elastic bending of the face sheet accompanied by non-linear deformation of the crushed foam

  19. Prediction of Failure Due to Thermal Aging, Corrosion and Environmental Fracture in Amorphous and Titanium Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J C

    2003-04-15

    DARPA is exploring a number of advanced materials for military applications, including amorphous metals and titanium-based alloys. Equipment made from these materials can undergo degradation due to thermal aging, uniform corrosion, pitting, crevice corrosion, denting, stress corrosion cracking, corrosion fatigue, hydrogen induced cracking and microbial influenced corrosion. Amorphous alloys have exceptional resistance to corrosion, due in part to the absence of grain boundaries, but can undergo crystallization and other phase instabilities during heating and welding. Titanium alloys are extremely corrosion resistant due to the formation of a tenacious passive film of titanium oxide, but is prone to hydrogen absorption in crevices, and hydrogen induced cracking after hydrogen absorption. Accurate predictions of equipment reliability, necessary for strategic planning, requires integrated models that account for all relevant modes of attack, and that can make probabilistic predictions. Once developed, model parameters must be determined experimentally, and the validity of models must be established through careful laboratory and field tests. Such validation testing requires state-of-the-art surface analytical techniques, as well as electrochemical and fracture mechanics tests. The interaction between those processes that perturb the local environment on a surface and those that alter metallurgical condition must be integrated in predictive models. The material and environment come together to drive various modes of corrosive attack (Figure 1). Models must be supported through comprehensive materials testing capabilities. Such capabilities are available at LLNL and include: the Long Term Corrosion Test Facility (LTCTF) where large numbers of standard samples can be exposed to realistic test media at several temperature levels; a reverse DC machine that can be used to monitor the propagation of stress corrosion cracking (SCC) in situ; and banks of potentiostats with

  20. Avaliação microscópica da movimentação dentária induzida em dentes traumatizados: um estudo experimental em ratos

    OpenAIRE

    2008-01-01

    O objetivo deste estudo foi avaliar microscopicamente os eventos biológicos da movimentação dentária induzida, 15 e 30 dias, após a aplicação de um trauma dentoalveolar experimental em molares de ratos. Foram utilizados trinta ratos, divididos em 6 grupos, com 5 animais por grupo: Grupo 1 - Grupo Controle; Grupo 2 – Grupo Movimentação Controle; Grupo 3 – Grupo Traumatismo Controle 1; Grupo 4 – Grupo Traumatismo e Movimentação 1; Grupo 5 – Grupo Traumatismo Controle 2; e Grupo 6 – Grupo Trauma...

  1. Placa bacteriana dentária em cães Dental bacterial plaque in dogs

    Directory of Open Access Journals (Sweden)

    Duvaldo Eurides

    1996-12-01

    Full Text Available Com objetivo de avaliar a incidência de placa bacteriana dentária, foram utilizados 30 cães, sem raça definida, distribuídos em três grupos iguais, de acordo com a faixa etária, sendo o grupo I de 0 a 2 anos, o grupo II de 3 a 5 anos e o grupo III acima de 6 anos. Os animais foram submetidos a anestesia geral e sobre os dentes foi aplicado cloreto de metilrosanilina, para evidenciar acúmulos bacterianos. As placas encontravam-se distribuídas em 80,99% no grupo I, 71,45% no grupo II e 83,96% no grupo III. Os grupos dentários foram considerados separadamente, apresentando índices de 64,84% nos dentes incisivos, 84,80% nos caninos, 87,23% nos pré-molares e 78,34% nos molares. Nos três grupos de cães observou-se índices semelhantes de placa bacteriana nos diferentes grupos dentários. Os animais do grupo II e o grupo de dentes incisivos apresentaram menores índices de placa bacteriana.To avaliate the incidence of bacterial plaque 30 mogreal dogs were utilizated, distributed among three equal groups. According to age, group I was composed of 0 to 2 years-old dogs, group II was 3 to 5 years-old, and group III over 6 years-old. The animals underwent a general anesthesia and metilrosanilin cloret was applied over the tooth, to evidence the bacterial mass. The plaques were distributed to 80.99% in group I, 71.42% in group II and 83.96% in group III. The dental groups were considerated apart, showing index of 64.84% on the incisar tooth, 84.80% on the canine tooth, 87.23% on the premolar tooth, and 78.34% on the molar tooth. At the dogs groups, similar Índex of bacterial plaque were observed on the diffèrent dental groups. The dogs from group II and the incisive tooth group showed minar bacterial plaque index.

  2. Monitoring Microbially Influenced Corrosion

    DEFF Research Database (Denmark)

    Hilbert, Lisbeth Rischel

    Abstract Microbially influenced corrosion (MIC) of carbon steel may occur in media with microbiological activity of especially sulphate-reducing bacteria (SRB). The applicability and reliability of a number of corrosion monitoring techniques for monitoring MIC has been evaluated in experiments...... and diffusional effects and unreliable corrosion rates, when biofilm and ferrous sulphide corrosion products cover the steel surface. Corrosion rates can be overestimated by a factor of 10 to 100 by electrochemical techniques. Weight loss coupons and ER are recommended as necessary basic monitoring techniques....... EIS might be used for detection of MIC as the appearance of very large capacitances can be attributed to the combined ferrous sulphide and biofilm formation. Capacitance correlates directly with sulphide concentration in sterile sulphide media. Keywords: Corrosion monitoring, carbon steel, MIC, SRB...

  3. Electrochemical corrosion studies

    Science.gov (United States)

    Knockemus, W. W.

    1986-01-01

    The objective was to gain familiarity with the Model 350 Corrosion Measurement Console, to determine if metal protection by grease coatings can be measured by the polarization-resistance method, and to compare corrosion rates of 4130 steel coated with various greases. Results show that grease protection of steel may be determined electrochemically. Studies were also conducted to determine the effectiveness of certain corrosion inhibitors on aluminum and steel.

  4. Erosion-corrosion; Erosionkorrosion

    Energy Technology Data Exchange (ETDEWEB)

    Aghili, B

    1999-05-01

    A literature study on erosion-corrosion of pipings in the nuclear industry was performed. Occurred incidents are reviewed, and the mechanism driving the erosion-corrosion is described. Factors that influence the effect in negative or positive direction are treated, as well as programs for control and inspection. Finally, examples of failures from databases on erosion-corrosion are given in an attachment 32 refs, 16 figs, tabs

  5. Coatings and Corrosion Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — Purpose: The mission of the Coatings and Corrosion Laboratory is to develop and analyze the effectiveness of innovative coatings test procedures while evaluating the...

  6. Monitoring Microbially Influenced Corrosion

    DEFF Research Database (Denmark)

    Hilbert, Lisbeth Rischel

    and diffusional effects and unreliable corrosion rates, when biofilm and ferrous sulphide corrosion products cover the steel surface. Corrosion rates can be overestimated by a factor of 10 to 100 by electrochemical techniques. Weight loss coupons and ER are recommended as necessary basic monitoring techniques....... EIS might be used for detection of MIC as the appearance of very large capacitances can be attributed to the combined ferrous sulphide and biofilm formation. Capacitance correlates directly with sulphide concentration in sterile sulphide media. Keywords: Corrosion monitoring, carbon steel, MIC, SRB...

  7. Corrosion in the oil industry

    Energy Technology Data Exchange (ETDEWEB)

    Brondel, D. (Sedco Forex, Montrouge (France)); Edwards, R. (Schlumberger Well Services, Columbus, OH (United States)); Hayman, A. (Etudes et Productions Schlumberger, Clamart (France)); Hill, D. (Schlumberger Dowell, Tulsa, OK (United States)); Mehta, S. (Schlumberger Dowell, St. Austell (United Kingdom)); Semerad, T. (Mobil Oil Indonesia, Inc., Sumatra (Indonesia))

    1994-04-01

    Corrosion costs the oil industry billions of dollars a year, a fact that makes the role of the corrosion engineer an increasingly important one. Attention is paid to how corrosion affects every aspect of exploration and production, from offshore rigs to casing. Also the role of corrosion agents such as drilling and production fluids is reviewed. Methods of control and techniques to monitor corrosion are discussed, along with an explanation of the chemical causes of corrosion. 21 figs., 32 refs.

  8. Profilaxia antimicrobiana em medicina dentária: uma revisão da literatura

    OpenAIRE

    Gonçalves, Inês Nabais

    2013-01-01

    Dissertação para obtenção do grau de Mestre no Instituto Superior de Ciências da Saúde Egas Moniz A profilaxia antimicrobiana em Medicina Dentária tem sido um tema muito discutido nos últimos anos na comunidade científica. Defende-se que os antibióticos profiláticos podem ser utilizados quer na prevenção da infeção local (no caso de procedimentos dentários invasivos como a cirurgia periodontal, cirurgia do terceiro molar, cirurgia de implantes e cirurgia ortognática), quer na prevenção ...

  9. Estudo biométrico em dentes de humanos Biometric study of human teeth

    Directory of Open Access Journals (Sweden)

    Carlos Alberto Gregório Cabrera

    2011-08-01

    Full Text Available OBJETIVO: determinar as dimensões biométricas de dentes humanos, nos sentidos mesiodistal, vestibulolingual e ocluso/inciso-cervical. MÉTODOS: utilizou-se uma amostra de modelos em gesso de 57 pacientes - 31 do sexo feminino (média de idade de 15 anos e 5 meses e 26 do masculino (média de idade de 16 anos e 6 meses. A amostra foi previamente qualificada, adotando-se o critério das "seis chaves para a oclusão perfeita" de Andrews, e teve seus valores compatibilizados com as variações obtidas por Bolton. Dois examinadores usaram um paquímetro digital com as pontas originais (curtas e outras modificadas (pontas longas. RESULTADOS E CONCLUSÕES: após os resultados serem submetidos aos testes estatísticos, constatou-se que os elementos dentários se mostraram simétricos nas arcadas dentárias em ambos os sexos. As dimensões dentárias são menores no sexo feminino, portanto, quando estudadas, devem ser separadas. Com os valores médios gerais obtidos, foi possível elaborar tabelas separadas quanto aos sexos, valores médios das três dimensões dentárias, porcentagem de ocorrência entre essas dimensões e seus respectivos desvios-padrão. Com esses valores foi possível desenvolver a denominada equação "C" e tabelas de percentis "C" e, com o auxílio de ambas, tornou-se possível aferir apenas uma das dimensões de um dente e encontrar as duas outras dimensões "prováveis" dos demais dentes das arcadas dentárias.Objective: To determine the biometric dimensions of human teeth in the mesiodistal, buccolingual and occlusal/incisal-cervical directions. Methods: It was used a sample of dental casts from 57 patients, i.e., 31 females with a mean age of 15 years and 5 months, and 26 males with a mean age of 16 years and 6 months. The sample was previously qualified by adopting the criteria established by Andrews' six keys to normal occlusion, whose values were matched to the variations obtained by Bolton. Two examiners used a digital

  10. Automatic Dent-landmark detection in 3-D CBCT dental volumes.

    Science.gov (United States)

    Cheng, Erkang; Chen, Jinwu; Yang, Jie; Deng, Huiyang; Wu, Yi; Megalooikonomou, Vasileios; Gable, Bryce; Ling, Haibin

    2011-01-01

    Orthodontic craniometric landmarks provide critical information in oral and maxillofacial imaging diagnosis and treatment planning. The Dent-landmark, defined as the odontoid process of the epistropheus, is one of the key landmarks to construct the midsagittal reference plane. In this paper, we propose a learning-based approach to automatically detect the Dent-landmark in the 3D cone-beam computed tomography (CBCT) dental data. Specifically, a detector is learned using the random forest with sampled context features. Furthermore, we use spacial prior to build a constrained search space other than use the full three dimensional space. The proposed method has been evaluated on a dataset containing 73 CBCT dental volumes and yields promising results.

  11. A gestão na medicina dentária

    OpenAIRE

    Castro, Andreia Sofia Freitas de

    2015-01-01

    Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária Em Portugal, contrariamente a outras especialidades médicas, a medicina dentária é exercida maioritariamente em consultórios privados, o que pressupõe que os médicos dentistas que gerem esses consultórios possuam conhecimentos de gestão empresarial. Com o elevado número de profissionais e grande oferta de serviços na área, há nece...

  12. Fatores associados à fluorose dentária = Factors associated with dental fluorosis

    Directory of Open Access Journals (Sweden)

    Rigo, Lilian

    2010-01-01

    Full Text Available Objetivo: Avaliar a prevalência e a severidade da fluorose dentária e verificar os fatores associados em adolescentes de escolas com atividades coletivas de promoção em saúde bucal. Metodologia: A amostra foi composta de 535 escolares de 12 e 15-19 anos moradores de um município da Região Sul do Brasil. Para a coleta de dados foram realizados exames clínicos utilizando o índice de Dean. As variáveis exploratórias demográficas, socioeconômicas, de acesso a serviços odontológicos e de hábitos de higiene bucal foram coletadas utilizandose um questionário semi-estruturado. Os dados foram analisados por análise de regressão logística múltipla. Resultados: A prevalência de fluorose dentária foi de 25%, sendo que o grau predominante foi o muito leve (18,3%. A fluorose foi associada ao sexo feminino (OR=1,55; IC95%1,03-2,32. Beber água de poço artesiano ou engarrafada foi um fator de proteção para fluorose no grupo de escolares investigado (OR=0,51; IC95% 0,27-0,95. Conclusão: A prevalência de fluorose dentária nos escolares desta amostra foi elevada, porém sua severidade foi baixa. A água ingerida e o sexo foram associados à fluorose dentária no modelo testado

  13. Autopercepção da perda de dentes em idosos

    Directory of Open Access Journals (Sweden)

    Beatriz Unfer

    2006-06-01

    Full Text Available O objetivo deste trabalho foi analisar as percepções de um grupo de idosos sobre a perda de dentes. Realizou-se uma pesquisa qualitativa que utilizou O Discurso do Sujeito Coletivo como técnica metodológica para a ordenação dos dados. A análise das entrevistas e a construção do Discurso do Sujeito Coletivo revelaram informações sobre os pensamentos e valores associados à perda de dentes no grupo. Os principais resultados sugerem que a falta de dentes trouxe problemas funcionais e psicológicos, mas que parecem ser compensados pela resolução do problema estético. As justificativas reveladas pelo sujeito coletivo para o edentulismo refletem predominantemente o modelo de atenção à saúde, em que predominam procedimentos cirúrgico-restauradores e reabilitadores, em detrimento de ações preventivas e educativas. Desta forma, torna-se imprescindível o desenvolvimento de iniciativas no campo da educação e prevenção em saúde bucal, enfatizando ações voltadas para a atenção integral do idoso, destacando-se a dimensão social das doenças e o papel do Estado como provedor da saúde e da qualidade de vida de todos os cidadãos.

  14. Ocorrência de desvio radicular em dentes de cão

    Directory of Open Access Journals (Sweden)

    Gioso Marco Antonio

    2000-01-01

    Full Text Available O presente trabalho analisa a ocorrência de desvio radicular em 115 incisivos centrais e intermédios, 34 caninos e 19 quarto pré-molares superiores, totalizando 168 dentes. O desvio foi avaliado por imagens de vídeo VHS sobrepostas a um quadriculado. Os resultados mostram que 77,4% dos incisivos apresentam desvios, sendo 61,0% moderados, 28,5% pequenos e 10,5% severos (estes, apenas nas extremidades do terço apical, de acordo com adaptação da técnica proposta por SCHNEIDER6 para determinação e classificação do grau de curvatura dos canais. Para os caninos anotam-se 47,1% dos dentes com desvio, sendo 75,0% moderados e 25,0% pequenos. E para os quarto pré-molares superiores observam-se 89,4% dos dentes com desvio, sendo 75,0% moderados, 16,7% pequenos e 8,3% severos. Comparados aos desvios radiculares observados na Odontologia Humana, concluímos que a ocorrência dos mesmos é baixa para a espécie canina facilitando a instrumentação do canal radicular.

  15. Clinical efficacy of medicinal treatment in 15 children with Dent disease%药物治疗 Dent 病15例的临床疗效

    Institute of Scientific and Technical Information of China (English)

    张宏博; 黄建萍

    2016-01-01

    Objective To investigate the drug effect of children with Dent disease who received therapy of po-tassium citrate and thiazide diuretics and angiotensin -converting enzyme inhibitors(ACEI),and to provide the refe-rence for the clinical treatment.Methods Dent disease patient who were followed -up in Bayi Children′s Hospital Af-filiated to Beijing Military Region General Hospital during the period of July 2006 and March 201 4 were selected.The patients were administered a therapy of potassium citrate associated with thiazide diuretics and ACEI according to the level of proteinuria and calciuria and serum potassium.The underlying changes before and after the treatment were com-pared and analyzed.Results In 1 5 children with Dent disease,they were all male cases,onset age ranged from 3 months to 1 1 years old[(2.62 ±3.1 1 )years old],and the disease duration ranged from 0.50 to 9.50 years old [(2.81 ±2.34)years].The patients were followed up for 0.50 to 7.50 years[(3.61 ±2.62)years].There was a sig-nificantly statistical difference in calcium/creatinine and daily Ca -creat ratio in contrast to before treatment[(0.41 ± 0.1 9)mg/mg vs(0.26 ±0.1 2)mg/mg,t =2.603,P =0.021 ;(6.76 ±2.0)mg/kg vs (4.34 ±1 .97)mg/kg,t =5.265,P =0.000],there was no significantly statistical difference in 24 -hour urinary protein quantity in contrast to before treatment[(0.96 ±0.62)g/24 h vs (0.87 ±0.44)g/24 h,t =1 .01 6,P =0.327].One case with kidney stone and 5 cases with nephrocalcinosis had a negative result of renal ultrasound after treatment.Conclusions Treatment of potassium citrate combination with thiazide diuretics and ACEI can significantly decrease urinary calcium excretion, make a disappearance of kidney stone and nephrocalcinosi,and it may have a role in protecting renal function.Treat-ment of benazepril can not significantly decrease the proteinuria and has no substantial improvement in low molecular weight protein urine.%目的:探讨枸橼酸钾联合氢氯噻嗪及

  16. Carbon Dioxide Corrosion:

    DEFF Research Database (Denmark)

    Fosbøl, Philip Loldrup

    2008-01-01

    CO2 corrosion is a general problem in the industry and it is expensive. The focus of this study is an oil gas production related problem. CO2 corrosion is observed in offshore natural gas transportation pipelines. A general overview of the problem is presented in chapter 1. The chemical system co...

  17. Corrosion evaluation technology

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Uh Chul; Han, Jeong Ho; Nho, Kye Ho; Lee, Eun Hee; Kim, Hong Pyo; Hwang, Seong Sik; Lee, Deok Hyun; Hur, Do Haeng; Kim, Kyung Mo

    1997-09-01

    A multifrequency ACPD system was assembled which can measure very small crack. Stress corrosion cracking test system with SSRT operating high temperature was installed. Stress corrosion cracking test of newly developed alloy 600 and existing alloy 600 was carried out in steam atmosphere of 400 deg C. No crack was observed in both materials within a test period of 2,000 hrs. Corrosion fatigue test system operating at high temperature was installed in which fatigue crack was measured by CDPD. Lead enhanced the SCC of the Alloy 600 in high temperature water, had a tendency to modify a cracking morphology from intergranular to transgranular. Pit initiation preferentially occurred at Ti-rich carbide. Resistance to pit initiation decreased with increasing temperature up to 300 deg C. Test loop for erosion corrosion was designed and fabricated. Thin layer activation technique was very effective in measuring erosion corrosion. Erosion corrosion of a part of secondary side pipe was evaluated by the Check Family Codes of EPRI. Calculated values of pipe thickness by Check Family Codes coincided with the pipe thickness measured by UT with an error of {+-} 20%. Literature review on turbine failure showed that failure usually occurred in low pressure turbine rotor disc and causes of failure are stress corrosion cracking and corrosion fatigue. (author). 12 refs., 20 tabs., 77 figs.

  18. Avionics Corrosion Control Study

    Science.gov (United States)

    1974-01-01

    found at seacoast (harsn) environnents is the most destructive. Differences in electrolte concentration and oxygen concentration promote corrosion...against corrosion by acting as moisture and gas barriers. CMCVIT B0.4ID *COATINGS Polyurethane’s, cprxies, silicones, and polystyrenes are the most

  19. A personal digital assistant application (MobilDent) for dental fieldwork data collection, information management and database handling.

    Science.gov (United States)

    Forsell, M; Häggström, M; Johansson, O; Sjögren, P

    2008-11-08

    To develop a personal digital assistant (PDA) application for oral health assessment fieldwork, including back-office and database systems (MobilDent). System design, construction and implementation of PDA, back-office and database systems. System requirements for MobilDent were collected, analysed and translated into system functions. User interfaces were implemented and system architecture was outlined. MobilDent was based on a platform with. NET (Microsoft) components, using an SQL Server 2005 (Microsoft) for data storage with Windows Mobile (Microsoft) operating system. The PDA devices were Dell Axim. System functions and user interfaces were specified for MobilDent. User interfaces for PDA, back-office and database systems were based on. NET programming. The PDA user interface was based on Windows suitable to a PDA display, whereas the back-office interface was designed for a normal-sized computer screen. A synchronisation module (MS Active Sync, Microsoft) was used to enable download of field data from PDA to the database. MobilDent is a feasible application for oral health assessment fieldwork, and the oral health assessment database may prove a valuable source for care planning, educational and research purposes. Further development of the MobilDent system will include wireless connectivity with download-on-demand technology.

  20. Autoestima e cárie dentária em adolescentes: um estudo seccional

    Directory of Open Access Journals (Sweden)

    Sandra Espíndola LUNARDELLI

    Full Text Available Resumo Introdução A cárie dentária na adolescência continua sendo um importante problema de saúde pública; entretanto, a sua relação com os fatores psicológicos é pouco estudada. Objetivo Estudar a possível associação entre aspectos de autoestima e cárie dentária em adolescentes. Material e método Estudo transversal envolvendo amostra de 409 adolescentes de 13 municípios do sul do Brasil. A cárie foi avaliada segundo critérios da Organização Mundial da Saúde e a autoestima, pela Escala de Rosenberg. O teste do qui-quadrado foi utilizado para determinar a significância estatística das associações. Para ajustar para variáveis de confusão, foi utilizada a regressão loglinear de Poisson com estimativa robusta. Resultado Foram observadas associações positivas entre presença de dentes cariados e alguns aspectos da escala de autoestima: “Às vezes, eu acho que não presto para nada” (p <0,001; “Eu gostaria de poder ter mais respeito comigo mesmo” (p=0,016, e “Eu, com certeza, me sinto inútil, às vezes” (p=0,022. Associação negativa foi observada com: “No conjunto, eu estou satisfeito comigo” (p=0,022. Na análise ajustada, os adolescentes com dentes cariados apresentaram maior prevalência de respostas positivas para a questão “Às vezes, eu acho que não presto para nada” [RP= 1,23 (IC 95% 1,05; 1,44] e maior prevalência de respostas negativas para a questão “No conjunto, eu estou satisfeito comigo” [RP= 1,12 (IC 95% 1,02; 1,24]. Conclusão Aspectos da autoestima foram, independente e significativamente, associados com a presença de dentes cariados.

  1. Anomalias dentárias de número em pacientes ortodônticos

    Directory of Open Access Journals (Sweden)

    Priscila Ferreira Torres

    Full Text Available ResumoIntroduçãoA prevalência e a distribuição das anomalias dentárias de número variam de acordo com a população estudada.ObjetivoDeterminar a prevalência de anomalias dentárias de número, verificando-se a frequência com relação a gênero, localização e dentes mais acometidos.MétodoForam avaliadas 1.054 radiografias panorâmicas de pacientes com idade entre 5 e 30 anos, realizadas no período de janeiro a março de 2010, em uma clínica particular de diagnóstico por imagem de Teresina-PI. Foram registrados dados relativos a gênero, idade, presença ou ausência de anomalia, dente acometido e localização. Foram realizados os testes estatísticos Qui-quadrado de Pearson e Teste Binominal, para duas proporções.ResultadoA hipodontia, com prevalência de 4,9%, foi encontrada com mais frequência na maxila, não apresentando diferença entre os lados e os gêneros. Os dentes mais ausentes foram: incisivos laterais superiores e segundo pré-molar inferior. Em relação à hiperdontia, com prevalência de 4,0%, não foram observadas diferenças entre gêneros, lados e maxilares. As regiões com maior presença de supranumerários foram: distal dos terceiros molares e entre pré-molares inferiores.ConclusãoFoi observada prevalência de hipodontia de 4,9%, sendo mais comum na maxila, e de hiperdontia de 4%, não apresentando diferença entre maxilares, lados e gêneros.

  2. Monitoring corrosion rates and localised corrosion in low conductivity water

    DEFF Research Database (Denmark)

    Hilbert, Lisbeth Rischel

    2006-01-01

    Monitoring of low corrosion rates and localised corrosion in a media with low conductivity is a challenge. In municipal district heating, quality control may be improved by implementing on-line corrosion monitoring if a suitable technique can be identified to measure both uniform and localised...... corrosion. Electrochemical techniques (LPR, EIS, crevice corrosion current) as well as direct measurement techniques (high-sensitive electrical resistance, weight loss) have been applied in operating plants. Changes in the corrosion processes are best monitored in non-aggressive, low conductivity media...... with sensitive electrical resistance technique and crevice corrosion current measurements....

  3. Mitigation of Corrosion on Magnesium Alloy by Predesigned Surface Corrosion

    OpenAIRE

    Xuming Zhang; Guosong Wu; Xiang Peng; Limin Li; Hongqing Feng; Biao Gao; Kaifu Huo; Chu, Paul K.

    2015-01-01

    Rapid corrosion of magnesium alloys is undesirable in structural and biomedical applications and a general way to control corrosion is to form a surface barrier layer isolating the bulk materials from the external environment. Herein, based on the insights gained from the anticorrosion behavior of corrosion products, a special way to mitigate aqueous corrosion is described. The concept is based on pre-corrosion by a hydrothermal treatment of Al-enriched Mg alloys in water. A uniform surface c...

  4. Corrosion Failures in Marine Environment

    Directory of Open Access Journals (Sweden)

    R. Krishnan

    1985-04-01

    Full Text Available This paper gives a brief description of typical marine environments and the most common form of corrosion of materials used in this environment. Some typical case histories of failures pertaining to pitting, bimetallic corrosion, dealloying, cavitation and stress corrosion cracking are illustrated as typical examples of corrosion failures.

  5. Corrosion Inhibitors for Reinforced Concrete

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    Steel corrosion in reinforced concrete structures has been a major problem across the U.S. Steel-reinforced concrete structures are continually subject to attack by corrosion brought on by naturally occurring environmental conditions. FerroGard, a corrosion inhibitor, developed by Sika Corporation, penetrates hardened concrete to dramatically reduce corrosion by 65% and extend the structure's service life.

  6. Automated Methods Of Corrosion Measurements

    DEFF Research Database (Denmark)

    Bech-Nielsen, Gregers; Andersen, Jens Enevold Thaulov; Reeve, John Ch

    1997-01-01

    The chapter describes the following automated measurements: Corrosion Measurements by Titration, Imaging Corrosion by Scanning Probe Microscopy, Critical Pitting Temperature and Application of the Electrochemical Hydrogen Permeation Cell.......The chapter describes the following automated measurements: Corrosion Measurements by Titration, Imaging Corrosion by Scanning Probe Microscopy, Critical Pitting Temperature and Application of the Electrochemical Hydrogen Permeation Cell....

  7. The Corrosion and Preservation of Iron Antiques.

    Science.gov (United States)

    Walker, Robert

    1982-01-01

    Discusses general corrosion reactions (iron to rust), including corrosion of iron, sulfur dioxide, chlorides, immersed corrosion, and underground corrosion. Also discusses corrosion inhibition, including corrosion inhibitors (anodic, cathodic, mixed, organic); safe/dangerous inhibitors; and corrosion/inhibition in concrete/marble, showcases/boxes,…

  8. Corrosion control in mining technology

    Energy Technology Data Exchange (ETDEWEB)

    Telekesi, J.

    1985-01-01

    An overview of corrosion effects in mining technology and the importance of protection is presented. The most common corrosion processes and effects are summarized and the system and criteria of their avoidance are discussed in detail. Preventive measures are recommended to decrease possible corrosion effects including the selection of corrosion-resistive constructions, to use protective coatings and inhibition techniques and some other protection possibilities where applicable. The organization aspects and the economic impact of corrosion control in mining are discussed.

  9. Corrosion-resistant uranium

    Science.gov (United States)

    Hovis, V.M. Jr.; Pullen, W.C.; Kollie, T.G.; Bell, R.T.

    1981-10-21

    The present invention is directed to the protecting of uranium and uranium alloy articles from corrosion by providing the surfaces of the articles with a layer of an ion-plated metal selected from aluminum and zinc to a thickness of at least 60 microinches and then converting at least the outer surface of the ion-plated layer of aluminum or zinc to aluminum chromate or zinc chromate. This conversion of the aluminum or zinc to the chromate form considerably enhances the corrosion resistance of the ion plating so as to effectively protect the coated article from corrosion.

  10. Abscesso perineal por ingestão acidental de palito de dente

    Directory of Open Access Journals (Sweden)

    Roberto Iglesias Lopes

    2006-06-01

    Full Text Available Palitos de dente são itens domésticos comuns e a maioria das pessoas subestima a gravidade das lesões que podem ocorrer com a ingestão acidental de palitos. Nós apresentamos um caso de abscesso perineal causado pela ingestão de um palito de dente. Um homem de 55 anos apresentou-se com quadro de dor perianal há um mês. Ao exame físico, notou-se abscesso perineal. Leucocitose com desvio à esquerda foi observada e a tomografia pélvica demonstrou um corpo estranho na região perineal. A remoção cirúrgica do corpo estranho e a drenagem adequada do abscesso foram realizadas, revelando um palito de dente. O paciente evoluiu bem após a abordagem cirúrgica. O abscesso perineal pode progredir para gangrena de Fournier e, portanto, a abordagem de abscessos perineais deve ser agressiva, com drenagem adequada e remoção do corpo estranho (sempre que presente.Toothpicks are a common household item and most people underestimate the seriousness of injuries that can occur with accidental ingestion. We report a case of a perineal abscess caused by an ingested toothpick. A 55-year-old man was admitted to the hospital with a 30-day history of perianal pain. Physical examination was unremarkable, except for a perineal abscess. Leucocytosis with 10% bands was present and pelvic tomography demonstrated a foreign body located in the perineal area. Surgical removal of the foreign body with adequate abscess drainage was performed revealing a toothpick. Perineal abscess may progress to Fournier's gangrene and as a consequence the management of a perineal abscess should be aggressive with adequate drainage and removal of the foreign body (if present.

  11. Introducing and evaluating MorphoDent, a Web-based learning program in dental morphology.

    Science.gov (United States)

    Mitov, Gergo; Dillschneider, Timo; Abed, Mohammad Rabbo; Hohenberg, Gregor; Pospiech, Peter

    2010-10-01

    MorphoDent, a computer-assisted learning program designed to teach the anatomy of the adult dentition, was introduced into the curriculum of dentistry at the University of Saarland in Homburg, Germany. Thirty-six second-year students of the School of Dentistry were introduced to morphoDent alongside the traditional lectures of dental anatomy. Questionnaires that evaluated the students' perceptions of virtual learning as well as aspects of the functionality of the program educational objectives were developed and distributed to the students. Online tests were performed and compared with a traditional examination. All questionnaires were returned. A wide variety of aspects dealing the pedagogic implications of e-learning were evaluated by the students, with the overall result being that students are aware of the needed hardware and technical skills and expect the quality of their studies to improve by implementation of e-learning. All sophomores except one felt that morphoDent had helped them in learning dental morphology and reported enjoying the virtual anatomical examination. One-third reported technical difficulties in operating the program. The average exam score was 2.53 (SD: 0.66) for the traditional and 2.23 (SD: 0.59) for the online dental anatomy test. Students expressed their positive attitude towards e-learning in general and indicated that the use of photorealistic 3D models of human teeth supported the process of individual learning of dental anatomy. The online test could be rated as a good option for students' self-performance rating.

  12. Métodos para acompanhamento do desgaste dentário no bruxismo

    OpenAIRE

    2009-01-01

    O desgaste dentário é um problema que incomoda pacientes e preocupa profissionais da Odontologia pois a perda de estrutura é irreversível e os danos podem desencadear dores. Acompanhar o desgaste é imprescindível para monitorar uma possível progressão e para se planejar uma intervenção. Pesquisas multidisciplinares agregam conhecimentos e profissionais distintos podem encontrar pontos comuns ou soluções diferentes que enriquecem o processo de pesquisa científica. Os métodos de monitoramento d...

  13. Computer-assisted learning and simulation lab with 40 DentSim units.

    Science.gov (United States)

    Welk, A; Maggio, M P; Simon, J F; Scarbecz, M; Harrison, J A; Wicks, R A; Gilpatrick, R O

    2008-01-01

    There are an increasing number of studies about the computer-assisted dental patient simulator DentSim (DenX, Israel), by which dental students can acquire cognitive motor skills in a multimedia environment. However, only a very few studies have been published dealing with efficient ways to use and to manage a computer-assisted dental simulation lab with 40 DentSim units. The current approach and optimization steps of the College of Dentistry at the University of Tennessee Health Science Center were evaluated based on theoretical and practical tests and by questionnaires (partial 5-point Likert scale). Half of the D1 (first-year) students (2004/05) already had experience with computer-assisted learning at their undergraduate college and most of the students even expected to be taught via computer-assisted learning systems (83.5%) at the dental school. 87.3% of the students working with DentSim found the experience to be very interesting or interesting. Before the students carried out the preparation exercises, they were trained in the skills they needed to work with the sophisticated technology, eg, system-specific operation skills (66.6% attained maximal reachable points) and information searching skills (79.5% attained maximal reachable points). The indirect knowledge retention rate / incidental learning rate of the preparation exercises in the sense of computer-assisted problem-oriented learning regarding anatomy, preparation procedures, and cavity design was promising. The wide- ranging number of prepared teeth needed to acquire the necessary skills shows the varied individual learning curves of the students. The acceptance of, and response to, additional elective training time in the computer-assisted simulation lab were very high. Integrating the DentSim technology into the existing curriculum is a way to improve dental education, but it is also a challenge for both teachers and the students. It requires a shift in both curriculum and instructional goals that

  14. Root abnormalities, talon cusps, dentes invaginati with reduced alveolar bone levels: case report.

    LENUS (Irish Health Repository)

    McNamara, C M

    1998-03-01

    This is a case report of a Caucasian female who presented with an unusual combination of dental anomalies: short roots on the maxillary central incisors and premolars, talon cusps, dentes invaginati, low alveolar bone heights, tubercles of Carabelli on the maxillary first and second permanent molars, with pyramidal root morphology in three of the second permanent molars. None of the anomalies alone are particularly uncommon but they have not previously been reported together. The occurrence of the anomalies is probably incidental as the conditions are aetiologically unrelated.

  15. Intrusão dentária utilizando mini-implantes

    OpenAIRE

    de Araújo, Telma Martins; Nascimento, Mauro Henrique Andrade; Franco,Fernanda Catharino Menezes; Bittencourt,Marcos Alan Vieira

    2008-01-01

    P. 36-48,set./out. INTRODUÇÃO: dentre os diversos tipos de movimentos dentários induzidos ortodonticamente, o de intrusão é, sem dúvida, um dos mais difíceis de serem conseguidos. A mecânica intrusiva convencional, apesar de viável, é complexa, no que diz respeito ao controle de seus efeitos colaterais. Isso, em grande parte, refere-se à dificuldade em se obter uma ancoragem satisfatória. Neste contexto, os mini-implantes, por oferecerem efetiva ancoragem esquelética, têm se mostrado de ex...

  16. Pacientes com Necessidades Especiais de Atendimento em Medicina Dentária

    OpenAIRE

    Bárbara, Mariana Clara Fonseca da

    2012-01-01

    Trabalho final do 5º ano com vista à atribuição do grau de mestre no âmbito do ciclo de estudos de Mestrado Integrado em Medicina Dentária apresentado à Faculdade de Medicina da Universidade de Coimbra. Introdução: Os pacientes com necessidades especiais de atendimento são todos aqueles cujas condições médicas, físicas, de desenvolvimento, comportamentais, emocionais ou outras de alguma forma limitantes, impliquem uma abordagem clínica diferenciada. Estas condições, adquiridas ou de desen...

  17. Corrosion Inhibitors for Aluminum.

    Science.gov (United States)

    Muller, Bodo

    1995-01-01

    Describes a simple and reliable test method used to investigate the corrosion-inhibiting effects of various chelating agents on aluminum pigments in aqueous alkaline media. The experiments that are presented require no complicated or expensive electronic equipment. (DDR)

  18. Modelling reinforcement corrosion in concrete

    DEFF Research Database (Denmark)

    Michel, Alexander; Geiker, Mette Rica; Stang, Henrik

    2012-01-01

    A physio-chemical model for the simulation of reinforcement corrosion in concrete struc-tures was developed. The model allows for simulation of initiation and subsequent propaga-tion of reinforcement corrosion. Corrosion is assumed to be initiated once a defined critical chloride threshold...... is reached causing the formation of anodic and cathodic regions along the reinforcement. Critical chloride thresholds, randomly distributed along the reinforcement sur-face, link the initiation and propagation phase of reinforcement corrosion. To demonstrate the potential use of the developed model......, a numerical example is pre-sented, that illustrates the formation of corrosion cells as well as propagation of corrosion in a reinforced concrete structure....

  19. Nine years of DentEd--a global perspective on dental education.

    Science.gov (United States)

    Reynolds, P A; Eaton, K A; Paganelli, C; Shanley, D

    2008-08-23

    This paper describes the three successive and successful DentEd projects, funded by the European Union, that established a productive thematic network which identified common content within the dental curriculum. It then developed an agreed professional profile, with a defined set of competences and a modular curriculum for all new dental graduates based on the European Credit Transfer System and trends in learning and assessment. The three phases took nine years to complete. Phase one investigated all aspects of dental undergraduate education and included over 30 visits to different dental schools by teams of dental educators. Phase two built on this work and included further visits to dental schools. Phase three refined the competency framework that had been developed in phase two and culminated in a global dental conference which finalised position papers on all aspects of dental education. The work and recommendations of the ICT in dental education group are considered in detail in the paper. The projects provided the stimulus for a number of European and international collaborations, including the web-based International Federation of Dental Education and Associations (IFDEA) Knowledge Centre and the International Virtual Dental School (IVIDENT), both of which aim to make increasingly sophisticated ICT-based educational material available worldwide and to promote international understanding.

  20. Corrosion and Corrosion Control in Light Water Reactors

    Science.gov (United States)

    Gordon, Barry M.

    2013-08-01

    Serious corrosion problems have plagued the light water reactor (LWR) industry for decades. The complex corrosion mechanisms involved and the development of practical engineering solutions for their mitigation will be discussed in this article. After a brief overview of the basic designs of the boiling water reactor (BWR) and pressurized water reactor (PWR), emphasis will be placed on the general corrosion of LWR containments, flow-accelerated corrosion of carbon steel components, intergranular stress corrosion cracking (IGSCC) in BWRs, primary water stress corrosion cracking (PWSCC) in PWRs, and irradiation-assisted stress corrosion cracking (IASCC) in both systems. Finally, the corrosion future of both plants will be discussed as plants extend their period of operation for an additional 20 to 40 years.

  1. Acción antimicrobiana in vitro de dentífricos conteniendo fitoterápicos

    Directory of Open Access Journals (Sweden)

    Liza Barreto V

    Full Text Available Este estudio analizó el potencial antimicrobiano in vitro de 7 dentífricos conteniendo fitoterápicos sobre bacterias orales recuperadas de la saliva y cepas patrón de S. mutans ATCC25175, S. sanguis ATCC 10556 y L. casei ATCC 4646. Fueron obtenidas soluciones concentradas de los dentífricos evaluados y de controles mezclándose 3 gramos de cada uno con 10 mL de agua deionozada estéril, seguido de centrifugación; los sobrenadantes resultantes fueron diluidos en proporciones de 1:2 hasta 1:32. Fue realizado un test de difusión en ágar, colocando cepas patrón y la saliva total estimulada de 10 pacientes saludables. Discos empapados con las suspensiones de los dentífricos fueron dispuestos en las placas, las cuales fueron incubadas en anaerobiosis por 48 horas, siendo los aros de inhibición medidos en milímetros. Los resultados obtenidos fueron analizados mediante ANOVA y llevando en consideración el control positivo se constató que, solamente las soluciones puras de los dentífricos presentaron capacidad antimicrobiana contra cepas patrón, equivalente a la del dentífrico con triclosan, excepto el Gessy Cristal®. Además, los dentífricos diluidos a 1:2 presentaron acción antimicrobiana contra las bacterias orales recuperadas de la saliva, excepto el Parodontax®.

  2. O valor social dos dentes e o acesso aos serviços odontológicos

    Directory of Open Access Journals (Sweden)

    Luciara Leão Viana Fonseca

    2015-10-01

    Full Text Available ResumoA assistência em Saúde Bucal no SUS enfrenta o desafio de responder ao perfil epidemiológico da população adulta. Com o objetivo de compreender as vivências, expectativas e percepção de acesso aos serviços pelas usuárias dos serviços de saúde do município de Diamantina-MG, foi realizada pesquisa qualitativa utilizando entrevista semiestruturada e a análise de conteúdo para avaliação dos dados. A apresentação e a discussão dos resultados basearam-se no diálogo entre o interacionismo simbólico e o conceito de habitus de Bourdieu. Os resultados mostram que as entrevistadas não davam, antes, importância ao cuidado com o dente, porque os procedimentos eram-lhes desconhecidos ou porque a prática dominante era a extração dentária. Hoje, valorizam os dentes e sofrem os constrangimentos sociais que causam a sua boca mal cuidada. Contudo, o acesso à restauração dos dentes pelo SUS não lhes é ainda possível. Para os filhos, percebem haver melhor acesso à informação e ao cuidado, mas para procedimentos especializados ainda encontram barreiras. Expressam resignação com o mau estado dos seus dentes e com as dificuldades de acesso, o que pode ser compreendido pelas exclusões já vividas que moldam suas ações no presente. Conclui-se que a assistência à Saúde Bucal do SUS deve incorporar a dimensão estética do dente como um direito social.

  3. Terapia pulpar em dentes decíduos: possibilidades terapêuticas baseadas em evidências

    Directory of Open Access Journals (Sweden)

    Natalino Lourenço Neto

    Full Text Available INTRODUÇÃO: A pulpotomia em dentes decíduos é uma técnica conservadora de terapia pulpar amplamente utilizada em Odontopediatria, sendo de fundamental importância para evitar a perda prematura desses dentes, quer seja por alterações provocadas pela cárie dentária ou traumatismo dentário. Apesar de ser uma técnica estudada há muitos anos, causa muitas controvérsias e discussões, principalmente em termos de biocompatibilidade dos medicamentos empregados e pelas dificuldades e falhas no diagnóstico da condição pulpar. OBJETIVO: Por meio de uma revisão sistemática da literatura, no período compreendido entre 2000 e 2011, e com enfoque em estudos clínicos randomizados, revisões sistemáticas e meta-análises, este trabalho teve como objetivo discutir, com base em evidências científicas, alternativas para o tratamento de pulpotomia em dentes decíduos humanos. CONCLUSÃO: As evidências científicas fidedignas com o uso de materiais capeadores pulpares e as técnicas de Eletrocirurgia e Laser de Baixa Potência foram escassas. Desta forma, sugere-se a realização de estudos complementares bem delineados estatisticamente para maiores esclarecimentos. As informações geradas em tais experimentos poderão contribuir para um melhor entendimento dos mecanismos da terapia pulpar, podendo gerar o desenvolvimento de protocolos com novas formas terapêuticas, que visam a melhorar a terapia pulpar em dentes decíduos.

  4. Efeito erosivo de medicamentos pediátricos de uso prolongado no esmalte de dentes decíduos

    OpenAIRE

    Camila Scatena

    2011-01-01

    O objetivo deste estudo foi avaliar o efeito in vitro de três medicamentos líquidos orais pediátricos de uso prolongado no esmalte de dentes decíduos. Sessenta incisivos superiores decíduos hígidos, recentemente esfoliados, foram seccionados de forma a expor a superfície vestibular e foram fixados em bases acrílicas. As superfícies foram polidas e os conjuntos dente/base acrílica foram impermeabilizados com duas camadas de esmalte cosmético para unhas, deixando exposta uma área de 2 mm² ...

  5. Tratamiento en sala de operaciones de dientes supernumerarios, inclusiones dentarias y quiste dentígero asociado

    OpenAIRE

    Aliaga Del Castillo, Rosalinda; Perea Paz, Miguel; De La Cruz Sedano, Gabriela Silvia; Aliaga Del Castillo, Arón

    2015-01-01

    Los dientes supernumerarios y las inclusiones de dientes permanentes son muy frecuentes en la infancia. Algunos dientes incluidos pueden estar asociados a la presencia de quistes dentígeros. Reportamos el caso de un paciente de sexo masculino de once años de edad con presencia de tresdientes supernumerarios en el maxilar superior, inclusión dentaria de pieza 11 e inclusión dentaria de pieza 13 con quiste dentígero asociado. El motivo de consulta fue precisamente la falta de las piezas 11 y 13...

  6. Corrosion testing using isotopes

    Science.gov (United States)

    Hohorst, Frederick A.

    1995-12-05

    A method for determining the corrosion behavior of a material with respect to a medium in contact with the material by: implanting a substantially chemically inert gas in a matrix so that corrosion experienced by the material causes the inert gas to enter the medium; placing the medium in contact with the material; and measuring the amount of inert gas which enters the medium. A test sample of a material whose resistance to corrosion by a medium is to be tested, composed of: a body of the material, which body has a surface to be contacted by the medium; and a substantially chemically inert gas implanted into the body to a depth below the surface. A test sample of a material whose resistance to corrosion by a medium is to be tested, composed of: a substrate of material which is easily corroded by the medium, the substrate having a surface; a substantially chemically inert gas implanted into the substrate; and a sheet of the material whose resistance to corrosion is to be tested, the sheet being disposed against the surface of the substrate and having a defined thickness.

  7. Severe Environmental Corrosion Erosion Facility

    Data.gov (United States)

    Federal Laboratory Consortium — NETL’s Severe Environment Corrosion Erosion Facility in Albany, OR, allows researchers to safely examine the performance of materials in highly corrosive or erosive...

  8. Corrosion-resistant metallic coatings

    OpenAIRE

    F. Presuel-Moreno; M.A. Jakab; N. Tailleart; Goldman, M.; J. R. Scully

    2008-01-01

    We describe recent computational and experimental studies on the corrosion properties of metallic coatings that can be tailored (tuned) to deliver up to three corrosion-inhibiting functions to an underlying substrate. Attributes are tuned by a selection of alloy compositions and nanostructures, ideally in alloy systems that offer flexibility of choice to optimize the corrosion-resisting properties. An amorphous Al-based coating is tuned for corrosion protection by on-demand release of ionic i...

  9. Corrosion-resistant metal surfaces

    Science.gov (United States)

    Sugama, Toshifumi [Wading River, NY

    2009-03-24

    The present invention relates to metal surfaces having thereon an ultrathin (e.g., less than ten nanometer thickness) corrosion-resistant film, thereby rendering the metal surfaces corrosion-resistant. The corrosion-resistant film includes an at least partially crosslinked amido-functionalized silanol component in combination with rare-earth metal oxide nanoparticles. The invention also relates to methods for producing such corrosion-resistant films.

  10. Plastics for corrosion inhibition

    CERN Document Server

    Goldade, Victor A; Makarevich, Anna V; Kestelman, Vladimir N

    2005-01-01

    The development of polymer composites containing inhibitors of metal corrosion is an important endeavour in modern materials science and technology. Corrosion inhibitors can be located in a polymer matrix in the solid, liquid or gaseous phase. This book details the thermodynamic principles for selecting these components, their compatibility and their effectiveness. The various mechanisms of metal protection – barrier, inhibiting and electromechanical – are considered, as are the conflicting requirements placed on the structure of the combined material. Two main classes of inhibited materials (structural and films/coatings) are described in detail. Examples are given of structural plastics used in friction units subjected to mechano-chemical wear and of polymer films/coatings for protecting metal objects against corrosion.

  11. Solving A Corrosion Problem

    Science.gov (United States)

    1979-01-01

    The corrosion problem, it turned out, stemmed from the process called electrolysis. When two different metals are in contact, an electrical potential is set up between them; when the metals are surrounded by an electrolyte, or a conducting medium, the resulting reaction causes corrosion, often very rapid corrosion. In this case the different metals were the copper grounding system and the ferry's aluminum hull; the dockside salt water in which the hull was resting served as the electrolyte. After identifying the source of the trouble, the Ames engineer provided a solution: a new wire-and-rod grounding system made of aluminum like the ferry's hull so there would no longer be dissimilar metals in contact. Ames research on the matter disclosed that the problem was not unique to the Golden Gate ferries. It is being experienced by many pleasure boat operators who are probably as puzzled about it as was the Golden Gate Transit Authority.

  12. Thin film corrosion. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Raut, M.K.

    1980-06-01

    Corrosion of chromium/gold (Cr/Au) thin films during photolithography, prebond etching, and cleaning was evaluated. Vapors of chromium etchant, tantalum nitride etchant, and especially gold etchant were found to corrosively attack chromium/gold films. A palladium metal barrier between the gold and chromium layers was found to reduce the corrosion from gold etchant.

  13. Corrosion resistant PEM fuel cell

    Science.gov (United States)

    Fronk, Matthew Howard; Borup, Rodney Lynn; Hulett, Jay S.; Brady, Brian K.; Cunningham, Kevin M.

    2002-01-01

    A PEM fuel cell having electrical contact elements comprising a corrosion-susceptible substrate metal coated with an electrically conductive, corrosion-resistant polymer containing a plurality of electrically conductive, corrosion-resistant filler particles. The substrate may have an oxidizable metal first layer (e.g., stainless steel) underlying the polymer coating.

  14. Estudo in vitro da eficácia anti-bacteriana de seis dentífricos em Streptococcus mutans e Lactobacillus acidophillus

    OpenAIRE

    Fernandes, Rita Maria Alves

    2009-01-01

    Monografia apresentada à Universidade Fernando Pessoa para obtenção do grau Licenciada em Medicina Dentária Os dentífricos são o veículo mais apropriado e eficiente para a libertação de agentes terapêuticos na cavidade oral, uma vez que a escovagem dentária é o método mais amplamente usado de higiene oral, tendo como principal objectivo a prevenção da cárie dentária e da doença periodontal. A enorme variedade de dentífricos disponíveis no mercado nacional, impõe sérias dific...

  15. Estudo in vitro da eficácia anti-bacteriana de seis dentífricos em Streptococcus mutans e Lactobacillus acidophillus

    OpenAIRE

    Fernandes, Rita Maria Alves

    2009-01-01

    Monografia apresentada à Universidade Fernando Pessoa para obtenção do grau Licenciada em Medicina Dentária Os dentífricos são o veículo mais apropriado e eficiente para a libertação de agentes terapêuticos na cavidade oral, uma vez que a escovagem dentária é o método mais amplamente usado de higiene oral, tendo como principal objectivo a prevenção da cárie dentária e da doença periodontal. A enorme variedade de dentífricos disponíveis no mercado nacional, impõe sérias dific...

  16. ProteÃnas salivares como biomarcadores para cÃrie dentÃria

    OpenAIRE

    Sarah Florindo de Figueiredo Guedes

    2014-01-01

    O nÃmero de estudos que correlacionam proteÃnas salivares e cÃrie dentÃria tÃm aumentado consideravelmente, no entanto, nÃo hà elementos suficientes que permitam qualificÃ-las como biomarcadores especÃficos para a doenÃa. O objetivo do estudo foi realizar uma anÃlise comparativa das proteÃnas da saliva de pacientes com cÃrie precoce da infÃncia (CPI) em diferentes nÃveis de severidade, visando à identificaÃÃo de potenciais biomarcadores salivares especÃficos para diagnÃstico desta patologia. ...

  17. Toxina Botulínica, considerações em Medicina Dentária

    OpenAIRE

    Teixeira, Natacha Betânia Alves

    2014-01-01

    Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária A toxina botulínica (TB) foi durante muito anos considerada um promotor de doença. No presente é considerada um agente terapêutico versátil para o tratamento de distúrbios musculares. O seu mecanismo de ação ocorre ao nível da fenda sináptica do músculo esquelético e leva a uma desnervação parcial e funcional dos neurónios motores, a...

  18. Resistência ao cisalhamento de dentes submetidos a duas técnicas de clareamento, pós-restaurados ou não

    Directory of Open Access Journals (Sweden)

    SIQUEIRA Evandro Luiz

    1997-01-01

    Full Text Available Os autores testaram a resistência ao cisalhamento de dentes submetidos a duas técnicas de clareamento. Foram utilizados 50 incisivos centrais superiores, divididos em 5 grupos, a saber: controle (só abertura coronária, clareamento sem calor, clareamento catalisado por calor controlado, clareamento catalisado por calor controlado e restauração com resina composta de última geração e dentes hígidos. Após o teste de cisalhamento, constatou-se que, nos dentes submetidos ao clareamento dental com perborato de sódio/Peridrol com ou sem aplicações de calor controlado, apesar de estes apresentarem leve diminuição da resistência ao cisalhamento, esta não é estatisticamente significante quando comparada com a dos dentes em que se executa o acesso endodôntico sem clareamento. A restauração do dente após o clareamento dental com adesivo dentinário de 4ª geração e resina fotopolimerizada aumenta a resistência do elemento dental clareado. Não existem diferenças estatísticas de resistência ao cisalhamento entre dentes clareados sem o uso de calor e aqueles em que o calor foi empregado de forma controlada, como preconizado neste estudo. Dentes hígidos apresentam resistência maior do que os dentes clareados com calor, sem calor e aqueles não clareados, com significância estatística no nível de 5%. Já com os dentes clareados e restaurados, os dentes hígidos não mostraram diferenças estatísticas significantes

  19. Receptor-mediated endocytosis and endosomal acidification is impaired in proximal tubule epithelial cells of Dent disease patients

    NARCIS (Netherlands)

    Gorvin, C.M.; Wilmer, M.J.G.; Piret, S.E.; Harding, B.; Heuvel, L.P.W.J. van den; Wrong, O.; Jat, P.S.; Lippiat, J.D.; Levtchenko, E.N.; Thakker, R.V.

    2013-01-01

    Receptor-mediated endocytosis, involving megalin and cubilin, mediates renal proximal-tubular reabsorption and is decreased in Dent disease because of mutations of the chloride/proton antiporter, chloride channel-5 (CLC-5), resulting in low-molecular-weight proteinuria, hypercalciuria, nephrolithias

  20. [From gene to disease; Dent's disease caused by abnormalities in the CLCN5 and OCRL1 genes

    NARCIS (Netherlands)

    Levtchenko, E.N.; Monnens, L.A.H.; Bokenkamp, A.; Knoers, N.V.A.M.

    2007-01-01

    Dent's disease is an X-linked disorder, characterized by generalized proximal tubular dysfunction, nephrolithiasis, nephrocalcinosis and the development ofend-stage renal disease, generally occurring after the age of thirty. In the majority of cases, the disease is caused by mutations in the CLCN5-g

  1. Associated dental anomalies: case report Múltiplas anomalias dentárias associadas: caso clínico

    Directory of Open Access Journals (Sweden)

    Daniela Gamba Garib

    2005-12-01

    Full Text Available Certain human dental anomalies frequently occur together, supporting the accumulated evidence of the shared genetic control of dental developmental disturbances. The present study reports a rare and interesting case of a 12-year-old girl with an association of multiple dental abnormalities, including agenesis, tooth malposition and delayed development. The etiology and treatment planning are discussed with reference to the literature. The clinical implications of genetically controlled patterns of dental anomalies are important in the establishment of early diagnosis and appropriate orthodontic intervention.Certas anomalias dentárias humanas freqüentemente ocorrem concomitantemente, contribuindo para validar as evidências do controle genético nos distúrbios de desenvolvimento. O presente estudo relata um caso raro e interessante de uma jovem de 12 anos de idade, com associação de anormalidades dentárias múltiplas, incluindo agenesia, ectopia e atraso no desenvolvimento dentário. A etiologia e tratamento planejados são discutidos com referência à literatura. As implicações clínicas do padrão de anomalias dentárias geneticamente controladas são importantes no estabelecimento do diagnóstico precoce e de adequada intervenção ortodôntica.

  2. Corrosion protection by anaerobiosis.

    Science.gov (United States)

    Volkland, H P; Harms, H; Wanner; Zehnder, A J

    2001-01-01

    Biofilm-forming bacteria can protect mild (unalloyed) steel from corrosion. Mild steel coupons incubated with Rhodoccocus sp. strain C125 and Pseudomonas putida mt2 in an aerobic phosphate-buffered medium containing benzoate as carbon and energy source, underwent a surface reaction leading to the formation of a corrosion-inhibiting vivianite layer [Fe3(PO4)2]. Electrochemical potential (E) measurements allowed us to follow the buildup of the vivianite cover. The presence of sufficient metabolically active bacteria at the steel surface resulted in an E decrease to -510 mV, the potential of free iron, and a continuous release of ferrous iron. Part of the dissolved iron precipitated as vivianite in a compact layer of two to three microns in thickness. This layer prevented corrosion of mild steel for over two weeks, even in a highly corrosive medium. A concentration of 20 mM phosphate in the medium was found to be a prerequisite for the formation of the vivianite layer.

  3. Smart Coatings for Corrosion Protection

    Science.gov (United States)

    Calle, Luz Marina; Li, Wendy; Buhrow, Jerry W.; Johnsey, Marissa N.

    2016-01-01

    Nearly all metals and their alloys are subject to corrosion that causes them to lose their structural integrity or other critical functionality. It is essential to detect corrosion when it occurs, and preferably at its early stage, so that action can be taken to avoid structural damage or loss of function. Protective coatings are the most commonly used method of corrosion control. However, progressively stricter environmental regulations have resulted in the ban of many commercially available corrosion protective coatings due to the harmful effects of their solvents or corrosion inhibitors. This work concerns the development of a multifunctional, smart coating for the autonomous control of corrosion. This coating is being developed to have the inherent ability to detect the chemical changes associated with the onset of corrosion and respond autonomously to indicate it and control it.

  4. Corrosion potential analysis system

    Science.gov (United States)

    Kiefer, Karl F.

    1998-03-01

    Many cities in the northeastern U.S. transport electrical power from place to place via underground cables, which utilize voltages from 68 kv to 348 kv. These cables are placed in seamless steel pipe to protect the conductors. These buried pipe-type-cables (PTCs) are carefully designed and constantly pressurized with transformer oil to prevent any possible contamination. A protective coating placed on the outside diameter of the pipe during manufacture protects the steel pipe from the soil environment. Notwithstanding the protection mechanisms available, the pipes remain vulnerable to electrochemical corrosion processes. If undetected, corrosion can cause the pipes to leak transformer oil into the environment. These leaks can assume serious proportions due to the constant pressure on the inside of the pipe. A need exists for a detection system that can dynamically monitor the corrosive potential on the length of the pipe and dynamically adjust cathodic protection to counter local and global changes in the cathodic environment surrounding the pipes. The northeastern United States contains approximately 1000 miles of this pipe. This milage is critical to the transportation and distribution of power. So critical, that each of the pipe runs has a redundant double running parallel to it. Invocon, Inc. proposed and tested a technically unique and cost effective solution to detect critical corrosion potential and to communicate that information to a central data collection and analysis location. Invocon's solution utilizes the steel of the casing pipe as a communication medium. Each data gathering station on the pipe can act as a relay for information gathered elsewhere on the pipe. These stations must have 'smart' network configuration algorithms that constantly test various communication paths and determine the best and most power efficient route through which information should flow. Each network station also performs data acquisition and analysis tasks that ultimately

  5. Scanning reference electrode techniques in localized corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Isaacs, H.S.; Vyas, B.

    1979-04-01

    The principles, advantages, and implementations of scanning reference electrode techniques are reviewed. Data related to pitting, intergranular corrosion, welds and stress corrosion cracking are presented. The technique locates the position of localized corrosion and can be used to monitor the development of corrosion and changes in the corrosion rate under a wide range of conditions.

  6. Cárie dentária: um novo conceito Dental caries: a new concept

    Directory of Open Access Journals (Sweden)

    José Eduardo de Oliveira Lima

    2007-12-01

    Full Text Available INTRODUÇÃO: a maneira como a cárie dentária é conceituada e seus fatores etiológicos considerados têm gerado divergências, na elaboração de estratégias preventivas, entre epidemiologistas e profissionais da saúde. As considerações e o conhecimento sobre a formação, progressão e definição da lesão de cárie devem ser aprofundados, para se estabelecer critérios que favoreçam o diagnóstico, a prevenção e o tratamento, preservando a qualidade de vida do paciente. O conceito de cárie dentária como doença infecciosa, transmissível e dieta dependente deve ser revisto, e os fatores etiológicos melhor interpretados e entendidos, para evitar estratégias de prevenção e tratamento equivocadas. É necessário um posicionamento mais conclusivo de instituições científicas e universidades, objetivando o estabelecimento definitivo desses conceitos, para que possam refletir-se em resultados práticos. OBJETIVO: o objetivo deste trabalho foi trazer uma contribuição baseada em 35 anos de exercício profissional e da vivência acadêmica no ensino e pesquisa e, também, realizar uma revisão da literatura de Cariologia, com a intenção de levar a uma interpretação dos achados científicos que permita um raciocínio lógico sobre o conceito de cárie dentária e dos fatores envolvidos em sua etiologia, podendo, com isso, chegar o mais próximo possível da verdade. RESULTADOS E CONCLUSÕES: os conhecimentos adquiridos até hoje, por meio da pesquisa científica e também a partir das conclusões deste trabalho, permitem elaborar estratégias preventivas mais eficientes em todo o planeta e a cárie dentária passará a ser, dentro de pouco tempo, um problema irrelevante ao ser humano. A partir do raciocínio desenvolvido neste trabalho, pode-se concluir que a cárie dentária não deve ser considerada uma doença, mas simplesmente uma lesão do esmalte de causa local, sem fatores etiológicos determinantes, porém provocada

  7. Corrosion Evaluation and Corrosion Control of Steam Generators

    Energy Technology Data Exchange (ETDEWEB)

    Maeng, W. Y.; Kim, U. C.; Sung, K. W.; Na, J. W.; Lee, Y. H.; Lee, D. H.; Kim, K. M

    2008-06-15

    Corrosion damage significantly influences the integrity and efficiency of steam generator. Corrosion problems of steam generator are unsolved issues until now even though much effort is made around world. Especially the stress corrosion cracking of heat exchange materials is the first issue to be solved. The corrosion protection method of steam generator is important and urgent for the guarantee of nuclear plant's integrity. The objectives of this study are 1) to evaluate the corrosion properties of steam generator materials, 2) to optimize the water chemistry of steam generator and 3) to develop the corrosion protection method of primary and secondary sides of steam generator. The results will be reflected to the water chemistry guideline for improving the integrity and efficiency of steam generator in domestic power plants.

  8. Estruturação de um Banco de Dentes Humanos Structuralization of a Human Teeth Bank

    Directory of Open Access Journals (Sweden)

    Alessandra Cristina da Silva Nassif

    2003-05-01

    Full Text Available Um Banco de Dentes Humanos (BDH é uma instituição sem fins lucrativos, vinculada a uma faculdade, universidade ou outra instituição. Seu propósito é suprir as necessidades acadêmicas, fornecendo dentes humanos para pesquisa ou para treinamento laboratorial pré-clínico dos alunos, dessa forma eliminando o comércio ilegal de dentes que ainda existe nas faculdades de Odontologia. Cabe também ao BDH zelar pela eliminação da infecção cruzada que existe no manuseio indiscriminado de dentes extraídos. Para o bom funcionamento de um BDH, é fundamental um controle severo de seus procedimentos internos, que incluem a separação e o estoque de dentes, assim como o cadastro e o arquivamento das fichas dos doadores ou beneficiários. Aqui, abordaremos as funções que um BDH pode desempenhar e a forma pela qual hoje o Banco de Dentes Humanos da Faculdade de Odontologia da Universidade de São Paulo (FOUSP funciona e organiza-se.A Human Teeth Bank (HTB is a nonprofit institution, associated to a college, to a university or to some other institution. Its purpose is to fulfill academic needs, by supplying human teeth for research or for preclinical laboratory training of students, thus eliminating the illegal commerce of teeth that still takes place in dental schools. It is also up to an HTB to work for the elimination of cross-infection caused by indiscriminate handling of extracted teeth. In order to work properly, an HTB should have a strict control of its internal procedures, which include separation and stocking of teeth, as well as an appropriate maintaining of donors' and beneficiaries' records. In this article, we discuss the functions that an HTB can perform, and how the Human Teeth Bank, School of Dentistry, University of São Paulo, works and organizes itself today.

  9. Ansiedade dentária em crianças - a importância da sua gestão na consulta de odontopediatria

    OpenAIRE

    2014-01-01

    A gestão da ansiedade dentária em crianças no decurso das consultas de Odontopediatria torna-se essencial para um maior sucesso dos tratamentos dentários. Assim, pretende-se avaliar os níveis de ansiedade manifestados pelas crianças face ao tratamento dentário e, simultaneamente, avaliar o grau de dor descrito no mesmo contexto clínico, de modo a relacioná-los diretamente com experiências prévias e outros fatores etiológicos de interesse, nomeadamente faixa etária, género, ansiedade parental ...

  10. Estudo epidemiológico de 261 dentes permanentes avulsionados de pacientes tratados em um serviço de urgência odontológica

    OpenAIRE

    Guedes,Orlando Aguirre

    2012-01-01

    Objetivo: Avaliar os aspectos epidemiológicos e fatores clínicos da avulsão de dentes permanentes. Material e Método: A amostra do estudo era composta por 170 pacientes (261 dentes avulsionados) atendidos no Serviço de Urgência Odontológica da Faculdade de Odontologia da Universidade Federal de Goiás, entre os anos de 2000 e 2008. As seguintes informações foram retiradas dos registros odontológicos de cada paciente: gênero, idade, fator etiológico, distribuição sazonal, grupo dentário, número...

  11. Ansiedade dentária em crianças - a importância da sua gestão na consulta de odontopediatria

    OpenAIRE

    Montagna, Diana Raquel Ferreira

    2014-01-01

    A gestão da ansiedade dentária em crianças no decurso das consultas de Odontopediatria torna-se essencial para um maior sucesso dos tratamentos dentários. Assim, pretende-se avaliar os níveis de ansiedade manifestados pelas crianças face ao tratamento dentário e, simultaneamente, avaliar o grau de dor descrito no mesmo contexto clínico, de modo a relacioná-los diretamente com experiências prévias e outros fatores etiológicos de interesse, nomeadamente faixa etária, género, ansiedade parental ...

  12. Corrosion-resistant metallic coatings

    Directory of Open Access Journals (Sweden)

    F. Presuel-Moreno

    2008-10-01

    Full Text Available We describe recent computational and experimental studies on the corrosion properties of metallic coatings that can be tailored (tuned to deliver up to three corrosion-inhibiting functions to an underlying substrate. Attributes are tuned by a selection of alloy compositions and nanostructures, ideally in alloy systems that offer flexibility of choice to optimize the corrosion-resisting properties. An amorphous Al-based coating is tuned for corrosion protection by on-demand release of ionic inhibitors to protect defects in the coating, by formation of an optimized barrier to local corrosion in Cl− containing environments, as well as by sacrificial cathodic prevention. Further progress in this field could lead to the design of the next generation of adaptive or tunable coatings that inhibit corrosion of underlying substrates.

  13. Automated methods of corrosion measurement

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov; Bech-Nielsen, Gregers; Reeve, John Ch

    1997-01-01

    Measurements of corrosion rates and other parameters connected with corrosion processes are important, first as indicators of the corrosion resistance of metallic materials and second because such measurements are based on general and fundamental physical, chemical, and electrochemical relations....... Hence improvements and innovations in methods applied in corrosion research are likeliy to benefit basic disciplines as well. A method for corrosion measurements can only provide reliable data if the beckground of the method is fully understood. Failure of a method to give correct data indicates a need...... to revise assumptions regarding the basis of the method, which sometimes leads to the discovery of as-yet unnoticed phenomena. The present selection of automated methods for corrosion measurements is not motivated simply by the fact that a certain measurement can be performed automatically. Automation...

  14. Corrosion inhibitors from expired drugs.

    Science.gov (United States)

    Vaszilcsin, Nicolae; Ordodi, Valentin; Borza, Alexandra

    2012-07-15

    This paper presents a method of expired or unused drugs valorization as corrosion inhibitors for metals in various media. Cyclic voltammograms were drawn on platinum in order to assess the stability of pharmaceutically active substances from drugs at the metal-corrosive environment interface. Tafel slope method was used to determine corrosion rates of steel in the absence and presence of inhibitors. Expired Carbamazepine and Paracetamol tablets were used to obtain corrosion inhibitors. For the former, the corrosion inhibition of carbon steel in 0.1 mol L(-1) sulfuric acid solution was about 90%, whereas for the latter, the corrosion inhibition efficiency of the same material in the 0.25 mol L(-1) acetic acid-0.25 mol L(-1) sodium acetate buffer solution was about 85%.

  15. Automated methods of corrosion measurement

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov; Bech-Nielsen, Gregers; Reeve, John Ch

    1997-01-01

    Measurements of corrosion rates and other parameters connected with corrosion processes are important, first as indicators of the corrosion resistance of metallic materials and second because such measurements are based on general and fundamental physical, chemical, and electrochemical relations....... Hence improvements and innovations in methods applied in corrosion research are likeliy to benefit basic disciplines as well. A method for corrosion measurements can only provide reliable data if the beckground of the method is fully understood. Failure of a method to give correct data indicates a need...... to revise assumptions regarding the basis of the method, which sometimes leads to the discovery of as-yet unnoticed phenomena. The present selection of automated methods for corrosion measurements is not motivated simply by the fact that a certain measurement can be performed automatically. Automation...

  16. Nuclear corrosion science and engineering

    CERN Document Server

    2012-01-01

    Understanding corrosion mechanisms, the systems and materials they affect, and the methods necessary for accurately measuring their incidence is of critical importance to the nuclear industry for the safe, economic and competitive running of its plants. This book reviews the fundamentals of nuclear corrosion. Corrosion of nuclear materials, i.e. the interaction between these materials and their environments, is a major issue for plant safety as well as for operation and economic competitiveness. Understanding these corrosion mechanisms, the systems and materials they affect, and the methods to accurately measure their incidence is of critical importance to the nuclear industry. Combining assessment techniques and analytical models into this understanding allows operators to predict the service life of corrosion-affected nuclear plant materials, and to apply the most appropriate maintenance and mitigation options to ensure safe long term operation. This book critically reviews the fundamental corrosion mechani...

  17. Microbiologically Influenced Corrosion

    Science.gov (United States)

    2009-01-01

    in each dimen- sion than bacteria and archaea. Fungi are eukaryotic organisms. Yeasts , molds, and mushrooms are examples of fungi. The majority of...occurs widely in natural waters and can be carried out by a variety of organisms including bacteria, yeast , and fungi (42). Ghiorse (43) prepared a...and its alloys is due to an aluminum oxide passive film. Anodizing produces thicker insulating films and better corrosion resistance. The natural

  18. Corrosion resistant coating

    Science.gov (United States)

    Wrobleski, Debra A.; Benicewicz, Brian C.; Thompson, Karen G.; Bryan, Coleman J.

    1997-01-01

    A method of protecting a metal substrate from corrosion including coating a metal substrate of, e.g., steel, iron or aluminum, with a conductive polymer layer of, e.g., polyaniline, coating upon said metal substrate, and coating the conductive polymer-coated metal substrate with a layer of a topcoat upon the conductive polymer coating layer, is provided, together with the resultant coated article from said method.

  19. CORROSION PROTECTION OF ALUMINUM

    Science.gov (United States)

    Dalrymple, R.S.; Nelson, W.B.

    1963-07-01

    Treatment of aluminum-base metal surfaces in an autoclave with an aqueous chromic acid solution of 0.5 to 3% by weight and of pH below 2 for 20 to 50 hrs at 160 to 180 deg C produces an extremely corrosion-resistant aluminum oxidechromium film on the surface. A chromic acid concentration of 1 to 2% and a pH of about 1 are preferred. (D.C.W.)

  20. Corrosion of bio implants

    Indian Academy of Sciences (India)

    U Kamachi Mudali; T M Sridhar; Baldev Raj

    2003-06-01

    Chemical stability, mechanical behaviour and biocompatibility in body fluids and tissues are the basic requirements for successful application of implant materials in bone fractures and replacements. Corrosion is one of the major processes affecting the life and service of orthopaedic devices made of metals and alloys used as implants in the body. Among the metals and alloys known, stainless steels (SS), Co–Cr alloys and titanium and its alloys are the most widely used for the making of biodevices for extended life in human body. Incidences of failure of stainless steel implant devices reveal the occurrence of significant localised corroding viz., pitting and crevice corrosion. Titanium forms a stable TiO2 film which can release titanium particles under wear into the body environment. To reduce corrosion and achieve better biocompatibility, bulk alloying of stainless steels with titanium and nitrogen, surface alloying by ion implantation of stainless steels and titanium and its alloys, and surface modification of stainless steel with bioceramic coatings are considered potential methods for improving the performance of orthopaedic devices. This review discusses these issues in depth and examines emerging directions.

  1. Corrosion in supercritical fluids

    Energy Technology Data Exchange (ETDEWEB)

    Propp, W.A.; Carleson, T.E.; Wai, Chen M.; Taylor, P.R.; Daehling, K.W.; Huang, Shaoping; Abdel-Latif, M.

    1996-05-01

    Integrated studies were carried out in the areas of corrosion, thermodynamic modeling, and electrochemistry under pressure and temperature conditions appropriate for potential applications of supercritical fluid (SCF) extractive metallurgy. Carbon dioxide and water were the primary fluids studied. Modifiers were used in some tests; these consisted of 1 wt% water and 10 wt% methanol for carbon dioxide and of sulfuric acid, sodium sulfate, ammonium sulfate, and ammonium nitrate at concentrations ranging from 0.00517 to 0.010 M for the aqueous fluids. The materials studied were Types 304 and 316 (UNS S30400 and S31600) stainless steel, iron, and AISI-SAE 1080 (UNS G10800) carbon steel. The thermodynamic modeling consisted of development of a personal computer-based program for generating Pourbaix diagrams at supercritical conditions in aqueous systems. As part of the model, a general method for extrapolating entropies and related thermodynamic properties from ambient to SCF conditions was developed. The experimental work was used as a tool to evaluate the predictions of the model for these systems. The model predicted a general loss of passivation in iron-based alloys at SCF conditions that was consistent with experimentally measured corrosion rates and open circuit potentials. For carbon-dioxide-based SCFs, measured corrosion rates were low, indicating that carbon steel would be suitable for use with unmodified carbon dioxide, while Type 304 stainless steel would be suitable for use with water or methanol as modifiers.

  2. Corrosion detection by induction

    Science.gov (United States)

    Roddenberry, Joshua L.

    Bridges in Florida are exposed to high amounts of humidity due to the state's geography. This excess moisture results in a high incidence of corrosion on the bridge's steel support cables. Also, the inclusion of ineffective waterproofing has resulted in additional corrosion. As this corrosion increases, the steel cables, responsible for maintaining bridge integrity, deteriorate and eventually break. If enough of these cables break, the bridge will experience a catastrophic failure resulting in collapse. Repairing and replacing these cables is very expensive and only increases with further damage. As each of the cables is steel, they have strong conductive properties. By inducing a current along each group of cables and measuring its dissipation over distance, a picture of structural integrity can be determined. The purpose of this thesis is to prove the effectiveness of using electromagnetic techniques to determine cable integrity. By comparing known conductive values (determined in a lab setting) to actual bridge values, the tester will be able to determine the location and severity of any damage, if present.

  3. Corrosion Monitors for Embedded Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Alex L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pfeifer, Kent B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Casias, Adrian L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Howell, Stephen W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sorensen, Neil R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Missert, Nancy A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-05-01

    We have developed and characterized novel in-situ corrosion sensors to monitor and quantify the corrosive potential and history of localized environments. Embedded corrosion sensors can provide information to aid health assessments of internal electrical components including connectors, microelectronics, wires, and other susceptible parts. When combined with other data (e.g. temperature and humidity), theory, and computational simulation, the reliability of monitored systems can be predicted with higher fidelity.

  4. Automated Methods of Corrosion Measurements

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov

    1997-01-01

    electrochemical measurements as well as elemental analysis look very promising for elucidating corrosion reaction mechanisms. The study of initial surface reactions at the atomic or submicron level is becoming an important field of research in the understanding of corrosion processes. At present, mainly two...... scanning microscope techniques are employed investigating corrosion processes, and usually in situ: in situ scanning tunneling microscopy (in situ STM) and in situ scanning force microscopy (in situ AFM). It is these techniques to which attention is directed here....

  5. Panel report on corrosion in energy systems

    Energy Technology Data Exchange (ETDEWEB)

    None

    1979-06-01

    Corrosion problems in high-temperature (non aqueous) energy systems, corrosion in aqueous energy systems and institutional problems inhibiting the development of corrosion science and engineering are discussed. (FS)

  6. Panel report on corrosion in energy systems

    Energy Technology Data Exchange (ETDEWEB)

    None

    1979-06-01

    Corrosion problems in high-temperature (non aqueous) energy systems, corrosion in aqueous energy systems and institutional problems inhibiting the development of corrosion science and engineering are discussed. (FS)

  7. Mechanisms of metal dusting corrosion

    DEFF Research Database (Denmark)

    Hummelshøj, Thomas Strabo

    In this thesis the early stages of metal dusting corrosion is addressed; the development of carbon expanded austenite, C, and the decomposition hereof into carbides. Later stages of metal dusting corrosion are explored by a systematic study of stainless steel foils exposed to metal dusting...... influence of oxygen and carbon on the metal dusting corrosion is explored. The results indicate that exposure to metal dusting conditions have a detrimental effect on the resistance against oxidation and, conversely, that exposure to oxidation has a detrimental effect on the resistance towards metal dusting....... Consequently, a combination of carburizing and oxidizing conditions has a strong mutual catalyzing effect on the metal dusting corrosion....

  8. Evaluation of steel corrosion by numerical analysis

    OpenAIRE

    Kawahigashi, Tatsuo

    2017-01-01

    Recently, various non-destructive and numerical methods have been used and many cases of steel corrosion are examined. For example, methods of evaluating corrosion through various numerical methods and evaluating macrocell corrosion and micro-cell corrosion using measurements have been proposed. However, there are few reports on estimating of corrosion loss with distinguishing the macro-cell and micro-cell corrosion and with resembling an actuality phenomenon. In this study, for distinguishin...

  9. Resinas compostas vs amálgama de prata em restaurações de dentes posteriores

    OpenAIRE

    Fernandes, Rui Moreira da Rocha Pereira

    2014-01-01

    Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária Nos últimos anos, tem-se constatado um grande desenvolvimento a nível dos materiais restauradores, assim como uma maior exigência estética, tanto por médicos dentistas como pelos próprios pacientes, nas restaurações dentárias. A exigência estética por parte dos pacientes levou à necessidade da evolução dos materiais restaura...

  10. Hydration kinetics, physicochemical composition, and textural changes of transgenic corn kernels of flint, semi-flint, and dent varieties

    Directory of Open Access Journals (Sweden)

    Barbara Celuppi Marques

    2014-03-01

    Full Text Available The hydration kinetics of transgenic corn types flint DKB 245PRO, semi-flint DKB 390PRO, and dent DKB 240PRO was studied at temperatures of 30, 40, 50, and 67 °C. The concentrated parameters model was used, and it fits the experimental data well for all three cultivars. The chemical composition of the corn kernels was also evaluated. The corn cultivar influenced the initial rate of absorption and the water equilibrium concentration, and the dent corn absorbed more water than the other cultivars at the four temperatures analyzed. The effect of hydration on the kernel texture was also studied, and it was observed that there was no significant difference in the deformation force required for all three corn types analyzed with longer hydration period.

  11. Higiene dentária: relato de uma experiência com grupos de mães

    Directory of Open Access Journals (Sweden)

    Gisele Mussi Corrêa

    1984-12-01

    Full Text Available É analisada a experiência desenvolvida com grupos de mães que freqüentam o Ambulatório de Pediatria do Instituto da Criança - Professor Pedro de Alcantara do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, orientando-as na higiene dentária infantil. A experiência demonstrou que, somente a partir de uma educação contínua às mães, haverá uma redução sensível do índice de cárie dentária na população brasileira.

  12. O papel da acupunctura na medicina dentária: uma revisão de literatura

    OpenAIRE

    Gonçalves, Inês Henriques

    2014-01-01

    Dissertação para obtenção do grau de Mestre no Instituto Superior de Ciências da Saúde Egas Moniz A dor e a ansiedade na medicina dentária continuam, ainda nos dias de hoje, a fazer com que a ida ao médico dentista se torne num desafio tão perturbador que, na maior parte das vezes, as pessoas não procurem os cuidados de saúde médico-dentários. O médico dentista deve tentar proporcionar o melhor tratamento para cada paciente, atendendo às características e exigências de cada um. Nos proc...

  13. Effects of Controlled-Release Fertilizers and Their Application Methods on Germination and Seedling Growth of Dent and Sweet Corns

    Institute of Scientific and Technical Information of China (English)

    TIAN Xiao-hong; SAIGUSA Masahiko; KIKAWA Naoto

    2005-01-01

    Effects of controlled-release fertilizers (CRFs) (C-AS, polyolefin coated ammonium sulfate, 50-day-type; Dd-LP, polyolefin coated urea with dicyandiamide, 40-day-type; C-ANP, polyolefin coated ammonium nitrate phosphate, 40-day-type; and C-DAP, polyolefin coated diammonium acid phosphate, 40-day-type), ammonium sulphate and no fertilizer control, and their application methods (spot, band, surface and mixed) on germination and seedling development of sweet corn (Zea mays L.var. saccharata Sturt.) and dent corn (Zea mays L.var. indentata Sturt.) were investigated in a greenhouse. Under co-situs application (band and spot) of CRFs, there were no obvious differences in the germination speed and rate for both dent corn and sweet corn relative to control. Mortality rates of sweet corn seedlings under co-situs application were high in experiment 1, but were very low in experiment 2, because the environmental conditions were different in the two experiments. That is, under lower temperature and weaker sunlight, young seedlings easily die due to high soil nutrient concentration and slow growth speed of corn. Shoot weight of both dent and sweet corn did not greatly decrease in experiment 1. In experiment 2, there were no significant differences in shoot and root weight of both corns between cositus and surface or mixed application methods. However, with spot and band application of ammonium sulfate, shoot and root weight were significantly reduced. Soil EC and pH were considerably affected by co-situs application, especially at the fertilizer application site. For both dent and sweet corn, EC in the 0-3 cm soil was significantly higher under co-situs application and surface application than that under mixed application, whereas in the 3-6 cm soil depth the situation was reversed. Compared with control, mixed application of CRFs decreased soil pH slightly (0-3 cm depth) or greatly (3-6 cm depth).

  14. Prevalência de fluorose dentária em escolares de Marinópolis, São Paulo

    Directory of Open Access Journals (Sweden)

    Ioneide Maria Gomes Brandão

    Full Text Available O objetivo deste estudo foi determinar a freqüência e severidade da fluorose dentária em escolares de 5 a 12 e de 15 anos de idade da cidade de Marinópolis, São Paulo, Brasil, com o propósito de se obter um banco de dados-base inicial para o monitoramento da fluorose dentária nesta população. Foram envolvidos todos os escolares de ambos os sexos, nas idades citadas, matriculados nas instituições de ensino da referida cidade e tendo como pré-requisito a condição de residirem em Marinópolis desde o nascimento, totalizando 320 escolares. Os exames foram realizados por um examinador previamente calibrado para a aplicação do Índice de Dean. De acordo com os resultados, a prevalência de fluorose dentária no grupo estudado foi de 17,2%; no entanto, considerando apenas os graus de fluorose que determinam comprometimento estético (leve, moderado e severo, o percentual foi de 7,19%. O grau predominante foi o muito leve (10,0% seguido pelos graus leve (5,3%, moderado (1,3% e severo (0,6%. Conclui-se que a fluorose dentária na população estudada não se constitui em problema de amplas dimensões; estudos posteriores, contudo, são necessários, a fim de identificar as causas da presença de casos de fluorose moderada e severa.

  15. Archaeological analogs and corrosion; Analogues archeologiques et corrosion

    Energy Technology Data Exchange (ETDEWEB)

    David, D

    2008-07-01

    In the framework of the high level and long life radioactive wastes disposal deep underground, the ANDRA built a research program on the material corrosion. In particular they aim to design containers for a very long time storage. Laboratory experiments are in progress and can be completed by the analysis of metallic archaeological objects and their corrosion after hundred years. (A.L.B.)

  16. Mitigation of Corrosion on Magnesium Alloy by Predesigned Surface Corrosion

    Science.gov (United States)

    Zhang, Xuming; Wu, Guosong; Peng, Xiang; Li, Limin; Feng, Hongqing; Gao, Biao; Huo, Kaifu; Chu, Paul K.

    2015-11-01

    Rapid corrosion of magnesium alloys is undesirable in structural and biomedical applications and a general way to control corrosion is to form a surface barrier layer isolating the bulk materials from the external environment. Herein, based on the insights gained from the anticorrosion behavior of corrosion products, a special way to mitigate aqueous corrosion is described. The concept is based on pre-corrosion by a hydrothermal treatment of Al-enriched Mg alloys in water. A uniform surface composed of an inner compact layer and top Mg-Al layered double hydroxide (LDH) microsheet is produced on a large area using a one-step process and excellent corrosion resistance is achieved in saline solutions. Moreover, inspired by the super-hydrophobic phenomenon in nature such as the lotus leaves effect, the orientation of the top microsheet layer is tailored by adjusting the hydrothermal temperature, time, and pH to produce a water-repellent surface after modification with fluorinated silane. As a result of the trapped air pockets in the microstructure, the super-hydrophobic surface with the Cassie state shows better corrosion resistance in the immersion tests. The results reveal an economical and environmentally friendly means to control and use the pre-corrosion products on magnesium alloys.

  17. Prevenção da reabsorção óssea alveolar após extração dentária

    OpenAIRE

    2016-01-01

    Introdução: O processo alveolar é o conjunto de osso que se encontra em redor da raiz do dente. Este osso é sensível a uma variedade de fatores ambientais e fisiológicos que influenciam a sua integridade e o seu funcionamento. Como tal, a sua formação assim como a sua preservação é dependente da presença contínua do dente. A reabsorção do processo alveolar após extração dentária é uma consequência natural e fisiológica indesejável, que pode dificultar a colocação de um implante dentário na po...

  18. Fluorose dentária: comparação de dois estudos de prevalência

    Directory of Open Access Journals (Sweden)

    Frazão Paulo

    2004-01-01

    Full Text Available Fluorose dentária é uma opacidade do esmalte provocada pela ingestão de quantidades excessivas de flúor (exposição crônica durante o período de formação dos dentes. A estimação desse problema em população exposta a fontes de flúor é necessária e deve ser feita periodicamente para monitorar os níveis e os padrões da alteração. A proposta desta pesquisa foi descrever e comparar dois estudos de prevalência para estimar a ocorrência de fluorose dentária na população do Município de Ribeirão Pires, Estado de São Paulo, Brasil, realizados em 1997 e 2000. Os métodos empregados em cada estudo foram brevemente apresentados. Os resultados foram comparados. Aspectos metodológicos e as implicações para Saúde Coletiva foram discutidos.

  19. Caracterização morfológica dos dentes de mocó Kerodon rupestris: Mammalia: Rodentia

    Directory of Open Access Journals (Sweden)

    Juliana Montovani Thomaz

    2006-10-01

    Full Text Available O Kerodon rupestris, também conhecido como mocó, é um roedor herbívoro encontrado no Brasil. A dentição dos mamíferos apresenta-se variável de acordo com as espécies embora seja formada pelos mesmos componentes: esmalte, dentina, cemento e polpa. Neste estudo foram utilizadas sete cabeças de Kerodon rupestris, adultos, de ambos os sexos. Na cavidade oral do Kerodon rupestris, devido ao tamanho relativamente grande dos incisivos, estes se destacaram dos demais e foram encontrados um par em cada mandíbula. Dois pares de pré-molares e três pares de molares foram encontrados, sendo representados na fórmula 2x (I 1/1, C 0/0, P 1/1, M 3/3. Os molares apresentaram duas cúspides, conformação que conferia a estes dentes um aspecto serrilhado. Microscopicamente os dentes incisivos, pré-molares e molares foram classificados como hipsodontes, ou seja, dentes em constante erupção.

  20. General Corrosion and Localized Corrosion of Waste Package Outer Barrier

    Energy Technology Data Exchange (ETDEWEB)

    K.G. Mon

    2004-10-01

    The waste package design for the License Application is a double-wall waste package underneath a protective drip shield (BSC 2004 [DIRS 168489]; BSC 2004 [DIRS 169480]). The purpose and scope of this model report is to document models for general and localized corrosion of the waste package outer barrier (WPOB) to be used in evaluating waste package performance. The WPOB is constructed of Alloy 22 (UNS N06022), a highly corrosion-resistant nickel-based alloy. The inner vessel of the waste package is constructed of Stainless Steel Type 316 (UNS S31600). Before it fails, the Alloy 22 WPOB protects the Stainless Steel Type 316 inner vessel from exposure to the external environment and any significant degradation. The Stainless Steel Type 316 inner vessel provides structural stability to the thinner Alloy 22 WPOB. Although the waste package inner vessel would also provide some performance for waste containment and potentially decrease the rate of radionuclide transport after WPOB breach before it fails, the potential performance of the inner vessel is far less than that of the more corrosion-resistant Alloy 22 WPOB. For this reason, the corrosion performance of the waste package inner vessel is conservatively ignored in this report and the total system performance assessment for the license application (TSPA-LA). Treatment of seismic and igneous events and their consequences on waste package outer barrier performance are not specifically discussed in this report, although the general and localized corrosion models developed in this report are suitable for use in these scenarios. The localized corrosion processes considered in this report are pitting corrosion and crevice corrosion. Stress corrosion cracking is discussed in ''Stress Corrosion Cracking of the Drip Shield, the Waste Package Outer Barrier, and the Stainless Steel Structural Material'' (BSC 2004 [DIRS 169985]).

  1. NiTi Alloys: New Materials that enable Shockproof, Corrosion Immune Bearings

    Science.gov (United States)

    DellaCorte, Christopher

    2017-01-01

    Though steel is the dominant material of choice for mechanical components (bearings and gears) it has intrinsic limitations related to corrosion and plastic deformation. In contrast, dimensionally stable nickel-rich Ni-Ti alloys, such as Nitinol 60, are intrinsically rustproof and can withstand high contact loads without damage (denting). Over the last decade, focused RD to exploit these alloys for new applications has revealed the science behind NiTi's remarkable properties. In this presentation, the state-of-the-art of nickel-rich NiTi alloys will be introduced along with a discussion of how NASA is adopting this new technology inside the space station water recycling system as a pathfinder for more down-to-earth tribological challenges.

  2. DPC materials and corrosion environments.

    Energy Technology Data Exchange (ETDEWEB)

    Ilgen, Anastasia Gennadyevna; Bryan, Charles R.; Teich-McGoldrick, Stephanie; Hardin, Ernest

    2014-10-01

    After an exposition of the materials used in DPCs and the factors controlling material corrosion in disposal environments, a survey is given of the corrosion rates, mechanisms, and products for commonly used stainless steels. Research needs are then identified for predicting stability of DPC materials in disposal environments. Stainless steel corrosion rates may be low enough to sustain DPC basket structural integrity for performance periods of as long as 10,000 years, especially in reducing conditions. Uncertainties include basket component design, disposal environment conditions, and the in-package chemical environment including any localized effects from radiolysis. Prospective disposal overpack materials exist for most disposal environments, including both corrosion allowance and corrosion resistant materials. Whereas the behavior of corrosion allowance materials is understood for a wide range of corrosion environments, demonstrating corrosion resistance could be more technically challenging and require environment-specific testing. A preliminary screening of the existing inventory of DPCs and other types of canisters is described, according to the type of closure, whether they can be readily transported, and what types of materials are used in basket construction.

  3. Agricultural Polymers as Corrosion Inhibitors

    Science.gov (United States)

    Agricultural polymers were composed of extra-cellular polysaccharides secreted by Leuconostoc mesenteroides have been shown to inhibit corrosion on corrosion-sensitive metals. The substantially pure exopolysaccharide has a general structure consisting of alpha(1-6)-linked D-glucose backbone and appr...

  4. INHIBITION OF CORROSION

    Science.gov (United States)

    Atherton, J.E. Jr.; Gurinsky, D.H.

    1958-06-24

    A method is described for preventing corrosion of metallic container materials by a high-temperature liquid bismuth flowing therein. The method comprises fabricating the containment means from a steel which contains between 2 and 12% chromium, between 0.5 and 1.5% of either molybdenum and silicon, and a minimum of nickel and manganese, and maintaining zirconium dissolved in the liquid bismuth at a concentration between 50 parts per million and its saturation value at the lowest temperature in the system.

  5. Fatigue and Corrosion in Metals

    CERN Document Server

    Milella, Pietro Paolo

    2013-01-01

    This textbook, suitable for students, researchers and engineers, gathers the experience of more than 20 years of teaching fracture mechanics, fatigue and corrosion to professional engineers and running experimental tests and verifications to solve practical problems in engineering applications. As such, it is a comprehensive blend of fundamental knowledge and technical tools to address the issues of fatigue and corrosion. The book initiates with a systematic description of fatigue from a phenomenological point of view, since the early signs of submicroscopic damage in few surface grains and continues describing, step by step, how these precursors develop to become mechanically small cracks and, eventually, macrocracks whose growth is governed by fracture mechanics. But fracture mechanics is also introduced to analyze stress corrosion and corrosion assisted fatigue in a rather advanced fashion. The author dedicates a particular attention to corrosion starting with an electrochemical treatment that mechanical e...

  6. IN DRIFT CORROSION PRODUCTS

    Energy Technology Data Exchange (ETDEWEB)

    D.M. Jolley

    1999-12-02

    As directed by a written development plan (CRWMS M&O 1999a), a conceptual model for steel and corrosion products in the engineered barrier system (EBS) is to be developed. The purpose of this conceptual model is to assist Performance Assessment Operations (PAO) and its Engineered Barrier Performance Department in modeling the geochemical environment within a repository drift, thus allowing PAO to provide a more detailed and complete in-drift geochemical model abstraction and to answer the key technical issues (KTI) raised in the NRC Issue Resolution Status Report (IRSR) for the Evolution of the Near-Field Environment (NFE) Revision 2 (NRC 1999). This document provides the conceptual framework for the in-drift corrosion products sub-model to be used in subsequent PAO analyses including the EBS physical and chemical model abstraction effort. This model has been developed to serve as a basis for the in-drift geochemical analyses performed by PAO. However, the concepts discussed within this report may also apply to some near and far-field geochemical processes and may have conceptual application within the unsaturated zone (UZ) and saturated zone (SZ) transport modeling efforts.

  7. Trauma dentário na infância: avaliação da conduta dos educadores de creches públicas de Patos-PB

    Directory of Open Access Journals (Sweden)

    Luciana Ellen Dantas Costa

    Full Text Available Introdução O trauma dental na infância ocorre em locais de assistência a essa fase e a conduta tomada pelos cuidadores, após o acidente, influencia diretamente no prognóstico. Objetivo: Avaliar o conhecimento dos Educadores de creches públicas sobre que condutas tomariam frente ao trauma dentário na infância. Metodologia: Por meio de estudo descritivo transversal, foi aplicado um questionário a 23 Educadores das creches públicas do Município de Patos-PB, para avaliar o perfil dos sujeitos e a conduta frente a situações emergenciais de trauma dentário nosescolares. A pesquisa foi aprovada pelo Comitê de Ética em Pesquisa do Centro de Saúde e Tecnologia Rural – UFCG, sob protocolo n.º 056/2011. Para análise e tabulação dos dados, foi utilizado o programa estatístico SPSS versão 18.0. Resultado: Observou-se que a maioria dos Educadores (91,3% nunca foi capacitada, não estando estes aptos a realizar o primeiro atendimento em caso de trauma dentário. Com relação ao tema avulsão dentária, 60,9% dos Educadores não saberiam o que fazer em caso de avulsão do dente permanente e 40,3%, do decíduo. Diante do dente avulsionado, 26,1% lavariam o dente rapidamente com água corrente, o armazenaria em um guardanapo, lenço ou algodão (21,7% e levaria a criança ao Cirurgião-Dentista. Diante de fratura coronária de dente, 34,8% guardariam o pedaço fraturado, enquanto que 39,1% não saberiam como proceder. Todos os entrevistados julgaram ser muito importante uma capacitação com os docentes, para realizar as primeiras medidas emergenciais frente ao trauma dentário. Conclusão: A maioria dos Educadores não está preparada para lidar com trauma dentário na infância, apresentando pouco ou nenhum conhecimento sobre o tema em questão, sendo necessária a inserção de programas que visem à capacitação docente em saúde bucal.

  8. Corrosion Prevention and Control Applications Guide

    Science.gov (United States)

    1987-03-31

    Money, Manpower Called Keys to Progress, Aviation Week & Space Technology, October 6, 1980. 12. Reboul , M. C., Galvanic Corrosion of Aluminum, National...PA, April 1980. 25. Reboul , M.C., Galvanic Corrosion of Aluminum, National Association of Corrosion Engineers, Corrosion, V. 35#9, September 1979. 146

  9. Investigation on Atmospheric Corrosiveness in Hainan Province

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    According to the results of four-year exposure tests for carbon steel samples in Hainan province, the influences of meteorological factors and Cl- on atmospheric corrosion were investigated. The feature of atmospheric corrosion in this area was summarized. A corrosive map for the area was drawn. The corrosion products on carbon steel at some typical places were analyzed by XRD and XPS.

  10. Recognition and Analysis of Corrosion Failure Mechanisms

    Directory of Open Access Journals (Sweden)

    Steven Suess

    2006-02-01

    Full Text Available Corrosion has a vast impact on the global and domestic economy, and currently incurs losses of nearly $300 billion annually to the U.S. economy alone. Because of the huge impact of corrosion, it is imperative to have a systematic approach to recognizing and mitigating corrosion problems as soon as possible after they become apparent. A proper failure analysis includes collection of pertinent background data and service history, followed by visual inspection, photographic documentation, material evaluation, data review and conclusion procurement. In analyzing corrosion failures, one must recognize the wide range of common corrosion mechanisms. The features of any corrosion failure give strong clues as to the most likely cause of the corrosion. This article details a proven approach to properly determining the root cause of a failure, and includes pictographic illustrations of the most common corrosion mechanisms, including general corrosion, pitting, galvanic corrosion, dealloying, crevice corrosion, microbiologically-influenced corrosion (MIC, corrosion fatigue, stress corrosion cracking (SCC, intergranular corrosion, fretting, erosion corrosion and hydrogen damage.

  11. A Multifunctional Coating for Autonomous Corrosion Control

    Science.gov (United States)

    Calle, Luz M.; Li, Wenyan; Buhrow, Jerry W.; Jolley, Scott t.

    2011-01-01

    Nearly all metals and their alloys are subject to corrosion that causes them to lose their structural integrity or other critical functionality. Protective coatings are the most commonly used method of corrosion control. However, progressively stricter environmental regulations have resulted in the ban of many commercially available corrosion protective coatings due to the harmful effects of their solvents or corrosion inhibitors. This work concerns the development of a multifunctional smart coating for the autonomous control of corrosion. This coating is being developed to have the inherent ability to detect the chemical changes associated with the onset of corrosion and respond autonomously to indicate it and control it. The multi-functionality of the coating is based on microencapsulation technology specifically designed for corrosion control applications. This design has, in addition to all the advantages of existing microcapsulation designs, the corrosion controlled release function that triggers the delivery of corrosion indicators and inhibitors on demand, only when and where needed. Microencapsulation of self-healing agents for autonomous repair of mechanical damage to the coating is also being pursued. Corrosion indicators, corrosion inhibitors, as well as self-healing agents, have been encapsulated and dispersed into several paint systems to test the corrosion detection, inhibition, and self-healing properties of the coating. Key words: Corrosion, coating, autonomous corrosion control, corrosion indication, corrosion inhibition, self-healing coating, smart coating, multifunctional coating, microencapsulation.

  12. Some peculiarities of corrosion of wheel steel

    Directory of Open Access Journals (Sweden)

    Alexander SHRAMKO

    2009-01-01

    Full Text Available Corrosion mechanism and rate of different chemical composition and structural condition of wheel steel were investigated. It was shown that “white layers”, variation in grain size and banding of wheel steel structure results in corrosion rate. Microstructure of steel from different elements of railway wheels after operation with corrosion was investigated. Wheel steel with addition of vanadium corroded more quickly than steel without vanadium. Non-metallic inclusions are the centre of corrosion nucleation and their influence on corrosion depends on type of inclusion. Mechanism of corrosion of wheel steel corrosion was discussed.

  13. Diffusion Coatings as Corrosion Inhibitors

    Science.gov (United States)

    Ivanov, Radoslav; Ignatova-Ivanova, Tsveteslava

    2016-03-01

    Corrosion is the cause of irretrievable loss of huge amounts of metals and alloys. The harmful effects of corrosion can be reduced significantly by applying appropriate methods of corrosion protection. One method to protect metals against corrosion is the formation of diffusion coatings on them. High corrosion resistance is typical for the boride diffusion layers. Aluminothermy is one of the main methods for diffusion saturation of the surface of metal products with various elements, including boron, and under certain conditions with aluminum, too. Samples of steel 45 were put to aluminothermic diffusion saturation with boron in a pressurized steel container at a temperature of 1100K, for 6 hours in powdered aluminothermic mixtures. The content of B2O3 in the starting mixtures decreased from the optimum - 20% to 0%, and the content of Al and the activator - (NH4)2.4BF3 is constant, respectively 7% and 0.5%. Al2O3 was used as filler. The borided samples were tested for corrosion resistance in 10% HCl for 72 hours. The results show that their corrosion resistance depends on the composition of the starting saturating mixture (mainly on the content of B2O3), and respectively on the composition, structure, thickness and degree of adhesion of the layer to the metal base.

  14. Corrosion behavior of duplex coatings

    Directory of Open Access Journals (Sweden)

    K. Raghu Ram Mohan Reddy

    2016-07-01

    Full Text Available The titanium alloys are used in defense, aerospace, automobile, chemical plants and biomedical applications due to their very high strength and lightweight properties. However, corrosion is a life-limiting factor when Ti alloys are exposed to different chemical environments at high temperatures. In the present paper, duplex NiCrAlY/WC–Co coating is coated onto Ti6Al4V substrate to investigate the corrosion behavior of both coated samples and the substrate. The duplex coating was performed with NiCrAlY as the intermediate coat of 200 μm thickness deposited by HVOF process and WC–Co ceramic top coat with varying thicknesses of 250 μm, 350 μm and 450 μm deposited by DS process. Potentiodynamic polarization tests were employed to investigate the corrosion performance of duplex coated samples and substrate in Ringer’s solution at 37 °C and pH value was set to 5.7. Finally the results reveal that 350 μm thick coated samples showed highest corrosion resistance compared to 250 μm thick samples as well as bare substrate. However, the 450 μm thick coated sample showed poor corrosion resistance compared to the substrate. The scale formed on the samples upon corrosion was characterized by using SEM analysis to understand the degree of corrosion behavior.

  15. Diffusion Coatings as Corrosion Inhibitors

    Directory of Open Access Journals (Sweden)

    Ivanov Radoslav

    2016-03-01

    Full Text Available Corrosion is the cause of irretrievable loss of huge amounts of metals and alloys. The harmful effects of corrosion can be reduced significantly by applying appropriate methods of corrosion protection. One method to protect metals against corrosion is the formation of diffusion coatings on them. High corrosion resistance is typical for the boride diffusion layers. Aluminothermy is one of the main methods for diffusion saturation of the surface of metal products with various elements, including boron, and under certain conditions with aluminum, too. Samples of steel 45 were put to aluminothermic diffusion saturation with boron in a pressurized steel container at a temperature of 1100K, for 6 hours in powdered aluminothermic mixtures. The content of В2О3 in the starting mixtures decreased from the optimum - 20% to 0%, and the content of Al and the activator - (NH42.4BF3 is constant, respectively 7% and 0.5%. Al2O3 was used as filler. The borided samples were tested for corrosion resistance in 10% HCl for 72 hours. The results show that their corrosion resistance depends on the composition of the starting saturating mixture (mainly on the content of В2О3, and respectively on the composition, structure, thickness and degree of adhesion of the layer to the metal base.

  16. Corrosion protection and control using nanomaterials

    CERN Document Server

    Cook, R

    2012-01-01

    This book covers the use of nanomaterials to prevent corrosion. The first section deals with the fundamentals of corrosion prevention using nanomaterials. Part two includes a series of case studies and applications of nanomaterials for corrosion control.$bCorrosion is an expensive and potentially dangerous problem in many industries. The potential application of different nanostructured materials in corrosion protection, prevention and control is a subject of increasing interest. Corrosion protection and control using nanomaterials explores the potential use of nanotechnology in corrosion control. The book is divided into two parts. Part one looks at the fundamentals of corrosion behaviour and the manufacture of nanocrystalline materials. Chapters discuss the impact of nanotechnology in reducing corrosion cost, and investigate the influence of various factors including thermodynamics, kinetics and grain size on the corrosion behaviour of nanocrystalline materials. There are also chapters on electrodeposition ...

  17. Corrosion Protection of Electrically Conductive Surfaces

    OpenAIRE

    Jian Song; Liangliang Wang; Andre Zibart; Christian Koch

    2012-01-01

    The basic function of the electrically conductive surface of electrical contacts is electrical conduction. The electrical conductivity of contact materials can be largely reduced by corrosion and in order to avoid corrosion, protective coatings must be used. Another phenomenon that leads to increasing contact resistance is fretting corrosion. Fretting corrosion is the degradation mechanism of surface material, which causes increasing contact resistance. Fretting corrosion occurs when there is...

  18. Critical Study of Corrosion Damaged Concrete Structures

    OpenAIRE

    Sallehuddin Shah Ayop; John Cairns

    2013-01-01

    Corrosion of steel reinforcement in concrete is one of the major problems with respect to the durability of reinforced concrete structures. The degradation of the structure strength due to reinforcement corrosion decreases its design life. This paper presents the literature study on the influence of the corrosion on concrete structure starting from the mechanism of the corrosion until the deterioration stage and the structural effects of corrosion on concrete structures.

  19. Shutdown corrosion in geothermal energy systems

    Energy Technology Data Exchange (ETDEWEB)

    Ellis, Peter F.

    1982-10-08

    Experience has shown that corrosion occurring during geothermal energy utilization system downtime--shutdown corrosion--can pose a serious threat to successful operations. Shutdown corrosion in geothermal plants appears more severe than would be expected in their nongeothermal analogs, and its mitigation may pose a severe challenge to corrosion engineering personnel. This paper presents four case histories of geothermal shutdown corrosion problems. General methods of mitigation are explored.

  20. Efeito do ascorbato de sódio na adesividade da resina composta em dentes clareados = Effect of sodium ascorbate on composite resin bond strength to bleached teeth

    Directory of Open Access Journals (Sweden)

    Xavier, Ana Claudia Carvalho

    2014-01-01

    Full Text Available Objetivo: Avaliar o efeito do ascorbato de sódio na adesão de resina composta em dentes submetidos a tratamento clareador. Métodos: Foram utilizados 40 pré-molares humanos, divididos em 4 grupos: C – (controle dentes não clareados; S – dentes clareados com peróxido de hidrogênio 35% e armazenados por 48 horas em saliva artificial; AS – dentes clareados com peróxido de hidrogênio 35% e irrigados com solução de ascorbato de sódio 10% por 10 minutos; AG – dentes submetidos a tratamento clareador com peróxido de hidrogênio 35% e imersos em gel de ascorbato de sódio 10% por 3 horas. Após a restauração, as amostras foram seccionadas e submetidas ao teste de microtração em máquina de ensaios universais (Emic sob velocidade de 1 mm/min. Os dados foram avaliados e submetidos aos testes estatísticos ANOVA e Tukey, com nível de significância 5%. Resultados: O grupo C apresentou o maior valor de adesividade, diferindo estatisticamente dos grupos S e AG. Conclusão: A manutenção dos dentes clareados em saliva por 48 horas não é suficiente para a recuperação da resistência adesiva. No entanto, a utilização da solução de ascorbato de sódio 10% por 10 minutos pode promover uma resistência adesiva adequada, permitindo a imediata restauração dos dentes

  1. Cracking and corrosion recovery boiler

    Energy Technology Data Exchange (ETDEWEB)

    Suik, H. [Tallinn Technical University, Horizon Pulp and Paper, Tallinn (Estonia)

    1998-12-31

    The corrosion of heat surfaces and the cracking the drums are the main problems of the recovery boiler. These phenomena have been appeared during long-term operation of boiler `Mitsubishi - 315` erected at 1964. Depth of the crack is depending on the number of shutdowns and on operation time. Corrosion intensity of different heat surfaces is varying depend on the metal temperature and the conditions at place of positioning of tube. The lowest intensity of corrosion is on the bank tubes and the greatest is on the tubes of the second stage superheater and on the tubes at the openings of air ports. (orig.) 5 refs.

  2. Corrosion-resistant coating development

    Energy Technology Data Exchange (ETDEWEB)

    Stinton, D.P.; Kupp, D.M.; Martin, R.L. [Oak Ridge National Lab., TN (United States)

    1997-12-01

    SiC-based heat exchangers have been identified as the prime candidate material for use as heat exchangers in advanced combined cycle power plants. Unfortunately, hot corrosion of the SiC-based materials created by alkali metal salts present in the combustion gases dictates the need for corrosion-resistant coatings. The well-documented corrosion resistance of CS-50 combined with its low (and tailorable) coefficient of thermal expansion and low modulus makes CS-50 an ideal candidate for this application. Coatings produced by gelcasting and traditional particulate processing have been evaluated.

  3. Corrosion-resistant sulfur concretes

    Science.gov (United States)

    McBee, W. C.; Sullivan, T. A.; Jong, B. W.

    1983-04-01

    Sulfur concretes have been developed by the Bureau of Mines as construction materials with physical and mechanical properties that suit them for use in acid and salt corrosive environments where conventional concretes fail. Mixture design methods were established for preparing sulfur concretes using different types of aggregates and recently developed mixed-modified sulfur cements. Bench-scale testing of the sulfur concretes has shown their potential value. Corrosion resistance, strength, and durability of sulfur concrete are superior to those of conventional materials. Field in situ evaluation tests of the sulfur concretes as replacement for conventional concrete materials are in progress in corrosive areas of 24 commercial chemical, fertilizer, and metallurgical plants.

  4. Review on Stress Corrosion and Corrosion Fatigue Failure of Centrifugal Compressor Impeller

    Institute of Scientific and Technical Information of China (English)

    SUN Jiao; CHEN Songying; QU Yanpeng; LI Jianfeng

    2015-01-01

    Corrosion failure, especially stress corrosion cracking and corrosion fatigue, is the main cause of centrifugal compressor impeller failure. And it is concealed and destructive. This paper summarizes the main theories of stress corrosion cracking and corrosion fatigue and its latest developments, and it also points out that existing stress corrosion cracking theories can be reduced to the anodic dissolution (AD), the hydrogen-induced cracking (HIC), and the combined AD and HIC mechanisms. The corrosion behavior and the mechanism of corrosion fatigue in the crack propagation stage are similar to stress corrosion cracking. The effects of stress ratio, loading frequency, and corrosive medium on the corrosion fatigue crack propagation rate are analyzed and summarized. The corrosion behavior and the mechanism of stress corrosion cracking and corrosion fatigue in corrosive environments, which contain sulfide, chlorides, and carbonate, are analyzed. The working environments of the centrifugal compressor impeller show the behavior and the mechanism of stress corrosion cracking and corrosion fatigue in different corrosive environments. The current research methods for centrifugal compressor impeller corrosion failure are analyzed. Physical analysis, numerical simulation, and the fluid-structure interaction method play an increasingly important role in the research on impeller deformation and stress distribution caused by the joint action of aerodynamic load and centrifugal load.

  5. Erosion--Corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Vyas, B.

    1978-01-01

    The deterioration of materials by corrosion or erosion by itself presents a formidable problem and for this reason investigators have studied these two phenomena independently. In fact, there are very few systematic studies on E-C and the majority of references mention it only in passing. In most real systems, however, the two destructive processes take place simultaneously, hence the purpose of this review is to present the various interactions between the chemical and mechanical agents leading to accelerated degradation of the material. The papers cited in the review are those that lead to a better understanding of the process involved in the accelerated rate of material loss under E-C conditions.

  6. Comparação de materiais usados na confeção de facetas dentárias

    OpenAIRE

    Monteiro, Eduardo Melo Pires

    2016-01-01

    A demanda na procura da reabilitação estética é um dos focos da história da humanidade ao longo das eras, mas que teve a sua acentuação nestes últimos dois séculos. Sendo a face um dos pontos que nos permite avaliar esteticamente uma pessoa, cabe ao médico dentista, como um dos profissionais que trabalha nessa zona do corpo humano, avaliar e procurar satisfazer as necessidades estéticas da população. Assim, por parte dos profissionais de Medicina Dentária, tem de haver uma procura const...

  7. Tratamiento de la hipersensibilidad dentinaria post terapia periodontal, mediante el uso de dos dentífricos desensibilizantes

    OpenAIRE

    ESPINOZA, J.; González, L.; Ruiz, P.

    2013-01-01

    Objetivo: El objetivo de este estudio fue evaluar y comparar la eficacia en la reducción de la hipersensibilidad dentinaria posterior a la terapia periodontal utilizando dentífricos que contienen arginina al 8% - carbonato de calcio versus acetato de estroncio al 8%, tras una y tres semanas de uso de las pastas dentales. Materiales y Método: Estudio clínico, aleatorio, ciego y controlado con dos grupos paralelos, y tres semanas de seguimiento, en el cual el universo de trabajo fue de 20 pacie...

  8. O uso de Probióticos como agentes antimicrobianos na cárie dentária

    OpenAIRE

    Basteiro, José Manuel Afonso

    2011-01-01

    Trabalho apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Ciências Farmacêuticas. A saúde oral é um factor muito importante para todos nós, pois uma boca não cuidada pode desencadear problemas graves na saúde. A principal patologia associada à cavidade oral é a cárie dentária, sendo universalmente reconhecida como uma doença multifactorial, que afecta cerca de 80% da população mundial. É causadora da destruição localizada d...

  9. Intrusão dentária utilizando mini-implantes Orthodontic intrusion with mini-implant anchorage

    OpenAIRE

    Telma Martins de Araújo; Mauro Henrique Andrade Nascimento; Fernanda Catharino Menezes Franco; Marcos Alan Vieira Bittencourt

    2008-01-01

    INTRODUÇÃO: dentre os diversos tipos de movimentos dentários induzidos ortodonticamente, o de intrusão é, sem dúvida, um dos mais difíceis de serem conseguidos. A mecânica intrusiva convencional, apesar de viável, é complexa, no que diz respeito ao controle de seus efeitos colaterais. Isso, em grande parte, refere-se à dificuldade em se obter uma ancoragem satisfatória. Neste contexto, os mini-implantes, por oferecerem efetiva ancoragem esquelética, têm se mostrado de extrema valia para os or...

  10. Desenvolvimento do germe dentário e do palato em fetos de camundongos sob o efeito da Sinvastatina

    Directory of Open Access Journals (Sweden)

    Fernanda Florian

    Full Text Available INTRODUÇÃO: As estatinas causaram uma revolução na prevenção e no tratamento do colesterol alto, porém é contraindicada no primeiro trimestre da gravidez, pois podem causar má formação no feto, no sistema nervoso central e nos membros. OBJETIVO: Verificar os efeitos da Sinvastatina na formação do palato e no desenvolvimento dos germes dentários dos primeiros molares superiores e inferiores. MATERIAL E MÉTODO: Para o acasalamento, foram utilizados 14 camundongos fêmeas e quatro machos; o dia 'zero' da gestação foi identificado pelo plug vaginal após acasalamento. As fêmeas prenhes foram divididas em Grupos I e III - receberam 10 mg/kg solução salina em três semanas antes do acasalamento e a partir do acasalamento até o 14.º dia de prenhez, respectivamente. Grupos II e IV receberam 10 mg/kg de Sinvastatina, no período de três semanas antes do acasalamento e a partir do acasalamento até o 14.º dia de prenhez, respectivamente. RESULTADO: A análise histológica dos fetos dos Grupos I, II, III e IV mostrou o palato fusionado na linha mediana do processo palatino. Os germes dentários dos primeiros molares dos Grupos II e IV apresentaram um desenvolvimento atrasado quando comparados aos Grupos I e III, porém, todos estavam nas etapas de capuz e campânula. CONCLUSÃO: As análises histológica e estatística mostraram que os fetos apresentaram palato fusionado na linha média de fusão do processo palatino e os germes dentários dos Grupos II e IV mostraram-se com formas indefinidas e contornos irregulares. Este estudo preliminar mostrou que a Sinvastatina pode ocasionar alterações morfológicas nos germes dentários.

  11. Greener Approach towards Corrosion Inhibition

    Directory of Open Access Journals (Sweden)

    Neha Patni

    2013-01-01

    Full Text Available Corrosion control of metals is technically, economically, environmentally, and aesthetically important. The best option is to use inhibitors for protecting metals and alloys against corrosion. As organic corrosion inhibitors are toxic in nature, so green inhibitors which are biodegradable, without any heavy metals and other toxic compounds, are promoted. Also plant products are inexpensive, renewable, and readily available. Tannins, organic amino acids, alkaloids, and organic dyes of plant origin have good corrosion-inhibiting abilities. Plant extracts contain many organic compounds, having polar atoms such as O, P, S, and N. These are adsorbed on the metal surface by these polar atoms, and protective films are formed, and various adsorption isotherms are obeyed. Various types of green inhibitors and their effect on different metals are mentioned in the paper.

  12. Corrosion Problems in Absorption Chillers

    Science.gov (United States)

    Stetson, Bruce

    1978-01-01

    Absorption chillers use a lithium bromide solution as the medium of absorption and water as the refrigerant. Discussed are corrosion and related problems, tests and remedies, and cleaning procedures. (Author/MLF)

  13. Accelerated corrosion test and corrosion failure distribution model of aircraft structural aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    LIU Wen-lin; MU Zhi-tao; JIN Ping

    2006-01-01

    Based on corrosion damage data of 10 years for a type of aircraft aluminum alloy, the statistical analysis was conducted by Gumbel, Normal and two parameters Weibull distribution function. The results show that aluminum alloy structural member has the corrosion history of pitting corrosion-intergranular corrosion-exfoliation corrosion, and the maximum corrosion depth is in conformity to normal distribution. The accelerated corrosion test was carried out with the complied equivalent airport accelerated environment spectrum. The corrosion damage failure modes of aluminum alloy structural member indicate that the period of validity of the former protective coating is about 2.5 to 3 years, and that of the novel protective coating is about 4.0 to 4.5 years. The corrosion kinetics law of aluminum spar flange was established by fitting corrosion damage test data. The law indicates two apparent corrosion stages of high strength aluminum alloy section material: pitting corrosion and intergranular corrosion/exfoliation corrosion.The test results agree with the statistical fit result of corrosion data collected from corrosion member in service. The fractional error is 5.8% at the same calendar year. The accelerated corrosion test validates the corrosion kinetics law of aircraft aluminum alloy in service.

  14. Electrochemical Studies of Atmospheric Corrosion.

    Science.gov (United States)

    1979-01-01

    Todynamlc polarization curves using a mod ifiedatmospheric corrosion mon i tor (ACM). Norma l Tafel behavior was observed , the limiting current for oxygen...following a suggestion of Peter Serada, who is heading a task group on time-of-wetness measurements In ASTM GO1 .04, in which the author is participating...about 5 papers except for 1968 where a symposium on atmospheric corrosion was held which resulted in the publ ication of an ASTM Special Technical

  15. Corrosion Control Anniston Army Depot

    Science.gov (United States)

    2010-02-09

    parts. • Anodize, Chrome, and Black Oxide (et.al.) • Substrate Prep and CARC paint. Stowage • Climate controlled storage (limited). • Weather...resistant (rain, uv) stowage . • Right Material – Right Time In Process Actions Bldgs 129 and 114 • Installation of new cleaning technologies for small... Rack Dehydration Prep Area CARC Application Flash-Off Oven De-mask and Anti- Corrosion App. Planned Future Actions Survey • Perform a corrosion survey

  16. Materials selection and corrosion problems

    Energy Technology Data Exchange (ETDEWEB)

    Cornet, I.; Greif, R.; Treseder, R.S.

    1974-06-28

    Data tabulated for chemical composition of geothermal waters are presented for four areas of interest in Nevada: Beowawe steam well and Beowawe Hot Spring, Buffalo Valley Hot Springs, Kyle Hot Springs, and Leach Hot Springs. Material recommendations were prepared for the Nevada geothermal well. A detailed field corrosion test program planned for the Nevada test well is included. A progress report is presented for a laboratory research program on velocity effects in corrosion. (MHR)

  17. Maintainability Improvement Through Corrosion Prediction

    Science.gov (United States)

    1997-12-01

    potential, current, pH, and chloride ion concentration were made along a simulated corrosion fatigue crack for HY80 (UNS K31820) steel in seawater...frequency range of 0.05-50 Hz, a 7075-T6 aluminium alloy and 304 and 316L stainless steels were fatigue tested in 3.0% NaCl solution. The increments...DESCRIPTORS: Conference Paper; Aluminum base alloys- Mechanical properties; Austenitic stainless steels - Mechanical properties; Corrosion fatigue

  18. Corrosion resistant neutron absorbing coatings

    Science.gov (United States)

    Choi, Jor-Shan [El Cerrito, CA; Farmer, Joseph C [Tracy, CA; Lee, Chuck K [Hayward, CA; Walker, Jeffrey [Gaithersburg, MD; Russell, Paige [Las Vegas, NV; Kirkwood, Jon [Saint Leonard, MD; Yang, Nancy [Lafayette, CA; Champagne, Victor [Oxford, PA

    2012-05-29

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  19. Investigations on Atmospheric Corrosion of Low carbon Steel in ...

    African Journals Online (AJOL)

    Nafiisah

    2008-07-17

    Jul 17, 2008 ... index which is directly related to the weight loss due to corrosion. The corrosion index ... easily observed by visual inspection, and the robust Gaussian filter was used. .... Method of removal of corrosion products from corrosion.

  20. Continuum and line modeling of disks around young stars II. Line diagnostics for GASPS from the DENT grid

    CERN Document Server

    Kamp, I; Pinte, C; Tilling, I; Thi, W -F; Menard, F; Duchene, G; Augereau, J -C

    2011-01-01

    Aims. We want to understand the chemistry and physics of disks on the basis of a large unbiased and statistically relevant grid of disk models. One of the main goals is to explore the diagnostic power of various gas emission lines and line ratios for deriving main disk parameters such as the gas mass. Methods. We explore the results of the DENT grid (Disk Evolution with Neat Theory) that consists of 300 000 disk models with 11 free parameters. Through a statistical analysis, we search for correlations and trends in an effort to find tools for disk diagnostic. Results. All calculated quantities like species masses, temperatures, continuum and line fluxes differ by several orders of magnitude across the entire parameter space. The broad distribution of these quantities as a function of input parameters shows the limitation of using a prototype T Tauri or Herbig Ae/Be disk model. The statistical analysis of the DENT grid shows that CO gas is rarely the dominant carbon reservoir in disks. Models with large inner ...

  1. Migrating corrosion inhibitor protection of concrete

    Energy Technology Data Exchange (ETDEWEB)

    Bjegovic, D.; Miksic, B.

    1999-11-01

    Migrating corrosion inhibitors (MCI) were developed to protect steel rebar from corrosion in concrete. They were designed to be incorporated as an admixture during concrete batching or used for surface impregnation of existing concrete structures. Two investigations are summarized. One studied the effectiveness of MCIs as a corrosion inhibitor for steel rebar when used as an admixture in fresh concrete mix. The other is a long-term study of MCI concrete impregnation that chronicles corrosion rates of rebar in concrete specimens. Based on data from each study, it was concluded that migrating corrosion inhibitors are compatible with concrete and effectively delay the onset of corrosion.

  2. Solutions of corrosion Problems in advanced Technologies

    DEFF Research Database (Denmark)

    Montgomery, Melanie; Karlsson, Asger

    1999-01-01

    Austenitic and ferritic steels were exposed in the superheater area of a straw-fired CHP plant. The specimens were exposed for 1400 hours at 450-600°C. The rate of corrosion was assessed based on unattacked metal remaining. The corrosion products and course of corrosion for the various steel types...... were investigated using light optical and scanning electron microscopy. The ferritic steels suffered from corrosion mainly via material loss. The austenitic steels suffered from predominantly selective corrosion resulting in chromium depletion from the alloy. A clear trend was observed that selective...... corrosion increased with increasing chromium content of the alloy....

  3. Corrosion behavior of corrosion resistant alloys in stimulation acids

    Energy Technology Data Exchange (ETDEWEB)

    Cheldi, Tiziana [ENI E and P Division, 20097 San Donato Milanese Milano (Italy); Piccolo, Eugenio Lo; Scoppio, Lucrezia [Centro Sviluppo Materiali, via Castel Romano 100, 00128 Rome (Italy)

    2004-07-01

    In the oil and gas industry, selection of CRAs for downhole tubulars is generally based on resistance to corrosive species in the production environment containing CO{sub 2}, H{sub 2}S, chloride and in some case elemental sulphur. However, there are non-production environments to which these materials must also be resistant for either short term or prolonged duration; these environments include stimulation acids, brine and completion fluids. This paper reports the main results of a laboratory study performed to evaluate the corrosion and stress corrosion behaviour to the acidizing treatments of the most used CRAs for production tubing and casing. Laboratory tests were performed to simulate both 'active' and 'spent' acids operative phases, selecting various environmental conditions. The selected steel pipes were a low alloyed steel, martensitic, super-martensitic, duplex 22 Cr, superduplex 25 Cr and super-austenitic stainless steels (25 Cr 35 Ni). Results obtained in the 'active' acid environments over the temperature range of 100-140 deg. C, showed that the blend acids with HCl at high concentration and HCl + HF represented too much severe conditions, where preventing high general corrosion and heavy localised corrosion by inhibition package becomes very difficult, especially for duplex steel pipe, where, in some case, the specimens were completely dissolved into the solution. On the contrary, all steels pipes were successfully protected by inhibitor when organic acid solution (HCOOH + CH{sub 3}COOH) were used. Furthermore, different effectiveness on corrosion protection was showed by the tested inhibitors packages: e.g. in the 90% HCl at 12% + 10 CH{sub 3}COOH acid blend. In 'spent' acid environments, all steel pipes showed to be less susceptible to the localised and general corrosion attack. Moreover, no Sulphide Stress Corrosion Cracking (SSC) was observed. Only one super-austenitic stainless steel U-bend specimen showed

  4. General Corrosion and Localized Corrosion of the Drip Shield

    Energy Technology Data Exchange (ETDEWEB)

    F. Hua

    2004-09-16

    The repository design includes a drip shield (BSC 2004 [DIRS 168489]) that provides protection for the waste package both as a barrier to seepage water contact and a physical barrier to potential rockfall. The purpose of the process-level models developed in this report is to model dry oxidation, general corrosion, and localized corrosion of the drip shield plate material, which is made of Ti Grade 7. This document is prepared according to ''Technical Work Plan For: Regulatory Integration Modeling and Analysis of the Waste Form and Waste Package'' (BSC 2004 [DIRS 171583]). The models developed in this report are used by the waste package degradation analyses for TSPA-LA and serve as a basis to determine the performance of the drip shield. The drip shield may suffer from other forms of failure such as the hydrogen induced cracking (HIC) or stress corrosion cracking (SCC), or both. Stress corrosion cracking of the drip shield material is discussed in ''Stress Corrosion Cracking of the Drip Shield, the Waste Package Outer Barrier, and the Stainless Steel Structural Material'' (BSC 2004 [DIRS 169985]). Hydrogen induced cracking of the drip shield material is discussed in ''Hydrogen Induced Cracking of Drip Shield'' (BSC 2004 [DIRS 169847]).

  5. Corrosion of steel structures in sea-bed sediment

    Indian Academy of Sciences (India)

    Xiutong Wang; Jizhou Duan; Yan Li; Jie Zhang; Shide Ma; Baorong Hou

    2005-04-01

    Seabed sediment (SBS) is a special soil that is covered by seawater. With the developments in marine oil exploitation and engineering, more and more steel structures have been buried in SBS. SBS corrosion has now become a serious problem in marine environment and an important issue in corrosion science. In this paper, approach in the field of SBS corrosion is reviewed. Electrochemical and microbial corrosion factors, corrosion mechanism, measurement of metal corrosion rate, corrosion evaluation and prediction of corrosion are also discussed here.

  6. Report on accelerated corrosion studies.

    Energy Technology Data Exchange (ETDEWEB)

    Mowry, Curtis Dale; Glass, Sarah Jill; Sorensen, Neil Robert

    2011-03-01

    Sandia National Laboratories (SNL) conducted accelerated atmospheric corrosion testing for the U.S. Consumer Product Safety Commission (CPSC) to help further the understanding of the development of corrosion products on conductor materials in household electrical components exposed to environmental conditions representative of homes constructed with problem drywall. The conditions of the accelerated testing were chosen to produce corrosion product growth that would be consistent with long-term exposure to environments containing humidity and parts per billion (ppb) levels of hydrogen sulfide (H{sub 2}S) that are thought to have been the source of corrosion in electrical components from affected homes. This report documents the test set-up, monitoring of electrical performance of powered electrical components during the exposure, and the materials characterization conducted on wires, screws, and contact plates from selected electrical components. No degradation in electrical performance (measured via voltage drop) was measured during the course of the 8-week exposure, which was approximately equivalent to 40 years of exposure in a light industrial environment. Analyses show that corrosion products consisting of various phases of copper sulfide, copper sulfate, and copper oxide are found on exposed surfaces of the conductor materials including wires, screws, and contact plates. The morphology and the thickness of the corrosion products showed a range of character. In some of the copper wires that were observed, corrosion product had flaked or spalled off the surface, exposing fresh metal to the reaction with the contaminant gasses; however, there was no significant change in the wire cross-sectional area.

  7. Detective probe prevents corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2001-07-01

    A black liquor recovery boiler is the main investment in a pulp mill, accounting for: about a third of the total cost of FIM 3-4 billion. Environmental aspects required that all the harmful chemicals involved in the process have to be kept within a pulp mill, rather than be released outside, and closed water circulation systems have to be introduced. These have led to the enrichment of some process and non-process chemicals causing corrosion problems and process disturbances in the boiler. The recovery boiler receives the liquor after the digestion stage, i.e. when woodchips are cooked to make cellulose, and burns it. During digestion, the wood produces out lignin, mixed with the liquor (consisting of sodium sulphide and hydroxide). The black liquor is burnt at the bottom of the boiler after the organic parts have been fired off. The rest goes into the recovery system and the chemicals are recycled producing energy, saving repurchasing chemicals and protecting the environment from toxic emissions.

  8. Considerações éticas e de biossegurança no tratamento dentário a pacientes seropositivos

    OpenAIRE

    Santos, André Filipe

    2011-01-01

    Trabalho apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária. O Médico Dentista é uma figura central na prestação de cuidados de saúde ao paciente seropositivo. As lesões orais relacionadas com o VIH são cada vez mais comuns e afectam profundamente a qualidade de vida destes pacientes, servindo ainda como indicadores precisos para o diagnóstico e estadiamento da infecção sistémica. Na medicina dentária ainda imperam muit...

  9. Quadros de patologia miofascial na clínica dentária: avaliação e terapêutica

    OpenAIRE

    Roxo, André

    2012-01-01

    Trabalho final do 5º ano com vista à atribuição do grau de mestre no âmbito do ciclo de estudos de Mestrado Integrado em Medicina Dentária apresentado à Faculdade de Medicina da Universidade de Coimbra. Os profissionais de saúde que trabalham em medicina dentária, encontram-se diariamente expostos a patologias musculares associadas às posturas de trabalho. Este tipo de patologias pode ser tratado ou a sintomatologia aliviada, com recurso a várias técnicas, como a acupunctura. A maio...

  10. 汽车发动机盖抗凹性的研究与应用%The Researching and Application of BIW Panel Denting on Vehicle Hood

    Institute of Scientific and Technical Information of China (English)

    张建伟; 柴志; 杨邦安

    2014-01-01

    某车型发动机盖抗凹性不足。本文对抗凹性的原理进行分析,并提出了改进建议,对发动机盖设计有较好的指导建议。%BIW panel denting of the vehicle hood is not meet target.In this paper, by analyzing the matter of BIW panel denting, and giving the melioration suggestion, which is prodound for the hood design.

  11. A importância da interação entre odontopediatrias e pediatrias no manejo de dentes natais e neonatais

    OpenAIRE

    2008-01-01

    OBJETIVO: Apresentar revisão de literatura sobre dentes natais e neonatais, abordando características clínicas, fatores etiológicos, medidas terapêuticas e a importância do conhecimento desta anomalia, por odontopediatras e pediatras. FONTES DE DADOS: Foram selecionados os artigos mais relevantes sobre o tema, desde 1950 até 2006, pesquisados no Medline e na Bibliografia Brasileira em Odontologia (BBO), além de livros de pertinentes. SÍNTESE DOS DADOS: Os dentes natais e neonatais consistem e...

  12. RESISTÊNCIA À FRATURA DE DENTES COM DIFERENTES GRAUS DE FRAGILIZAÇÃO RADICULAR RECONSTRUÍDOS COM OU SEM PINOS ACESSÓRIOS

    OpenAIRE

    Ricardo Abreu da Rosa

    2010-01-01

    No presente trabalho foi avaliada a resistência à fratura de dentes bovinos com diferentes graus de alargamento do conduto radicular e reconstruídos com pinos de fibra de vidro utilizados isoladamente ou associados a pinos acessórios de fibra de vidro. Foram selecionados 50 incisivos inferiores bovinos, de dimensões mésio-distal e vestíbulo-lingual similares, seccionados transversalmente a 14 mm do ápice radicular. O tecido pulpar foi removido e os dentes foram fixados em blocos de resina acr...

  13. Corrosion in Electronic Devices and Sensors to Prevent Corrosion

    Directory of Open Access Journals (Sweden)

    Siddharth Dev

    2014-02-01

    Full Text Available Many types of metal and alloys are used in various electronic devices and components like computers, microchips, printed circuit board (PCB, integrated circuits, transistors, and diodes etc. Such components have variety of applications in the field of medical, aerospace, automotive sectors, telecommunication and defense. These components are exposed to different types of environments. The increased used of electronics has also increased the demand for reliability. The size of electronic equipment is also very significant parameter and it has been decreasing presently at a faster rate. The smaller size of equipment has undetectable failures. Though the corrosion taking place in electronic components is generally of micro level which can not be detected easily but the services of device are seized. The paper deals with the various types of corrosion in electronic components as a case study and an approach towards development of some sensor for corrosion monitoring.

  14. Quantitative measures of corrosion and prevention: application to corrosion in agriculture

    NARCIS (Netherlands)

    Schouten, J.C.; Gellings, P.J.

    1987-01-01

    The corrosion protection factor (c.p.f.) and the corrosion condition (c.c.) are simple instruments for the study and evaluation of the contribution and efficiency of several methods of corrosion prevention and control. The application of c.p.f. and c.c. to corrosion and prevention in agriculture in

  15. Synergy effect of naphthenic acid corrosion and sulfur corrosion in crude oil distillation unit

    Science.gov (United States)

    Huang, B. S.; Yin, W. F.; Sang, D. H.; Jiang, Z. Y.

    2012-10-01

    The synergy effect of naphthenic acid corrosion and sulfur corrosion at high temperature in crude oil distillation unit was studied using Q235 carbon-manganese steel and 316 stainless steel. The corrosion of Q235 and 316 in corrosion media containing sulfur and/or naphthenic acid at 280 °C was investigated by weight loss, scanning electron microscope (SEM), EDS and X-ray diffractometer (XRD) analysis. The results showed that in corrosion media containing only sulfur, the corrosion rate of Q235 and 316 first increased and then decreased with the increase of sulfur content. In corrosion media containing naphthenic acid and sulfur, with the variations of acid value or sulfur content, the synergy effect of naphthenic acid corrosion and sulfur corrosion has a great influence on the corrosion rate of Q235 and 316. It was indicated that the sulfur accelerated naphthenic acid corrosion below a certain sulfur content but prevented naphthenic acid corrosion above that. The corrosion products on two steels after exposure to corrosion media were investigated. The stable Cr5S8 phases detected in the corrosion products film of 316 were considered as the reason why 316 has greater corrosion resistance to that of Q235.

  16. Quantitative measures of corrosion and prevention: application to corrosion in agriculture

    NARCIS (Netherlands)

    Schouten, J.C.; Gellings, P.J.

    1987-01-01

    The corrosion protection factor (c.p.f.) and the corrosion condition (c.c.) are simple instruments for the study and evaluation of the contribution and efficiency of several methods of corrosion prevention and control. The application of c.p.f. and c.c. to corrosion and prevention in agriculture in

  17. Corrosion effects on friction factors

    Energy Technology Data Exchange (ETDEWEB)

    Magleby, H.L.; Shaffer, S.J.

    1996-03-01

    This paper presents the results of NRC-sponsored material specimen tests that were performed to determine if corrosion increases the friction factors of sliding surfaces of motor-operated gate valves, which could require higher forces to close and open safety-related valves when subjected to their design basis differential pressures. Friction tests were performed with uncorroded specimens and specimens subjected to accelerated corrosion. Preliminary tests at ambient conditions showed that corrosion increased the friction factors, indicating the need for additional tests duplicating valve operating parameters at hot conditions. The additional tests showed friction factors of corroded specimens were 0.1 to 0.2 higher than for uncorroded specimens, and that the friction factors of the corroded specimens were not very dependent on contact stress or corrosion film thickness. The measured values of friction factors for the three corrosion films tested (simulating three operating times) were in the range of 0.3 to 0.4. The friction factor for even the shortest simulated operating time was essentially the same as the others, indicating that the friction factors appear to reach a plateau and that the plateau is reached quickly.

  18. Graphene: corrosion-inhibiting coating.

    Science.gov (United States)

    Prasai, Dhiraj; Tuberquia, Juan Carlos; Harl, Robert R; Jennings, G Kane; Rogers, Bridget R; Bolotin, Kirill I

    2012-02-28

    We report the use of atomically thin layers of graphene as a protective coating that inhibits corrosion of underlying metals. Here, we employ electrochemical methods to study the corrosion inhibition of copper and nickel by either growing graphene on these metals, or by mechanically transferring multilayer graphene onto them. Cyclic voltammetry measurements reveal that the graphene coating effectively suppresses metal oxidation and oxygen reduction. Electrochemical impedance spectroscopy measurements suggest that while graphene itself is not damaged, the metal under it is corroded at cracks in the graphene film. Finally, we use Tafel analysis to quantify the corrosion rates of samples with and without graphene coatings. These results indicate that copper films coated with graphene grown via chemical vapor deposition are corroded 7 times slower in an aerated Na(2)SO(4) solution as compared to the corrosion rate of bare copper. Tafel analysis reveals that nickel with a multilayer graphene film grown on it corrodes 20 times slower while nickel surfaces coated with four layers of mechanically transferred graphene corrode 4 times slower than bare nickel. These findings establish graphene as the thinnest known corrosion-protecting coating.

  19. Microencapsulation of Corrosion Indicators for Smart Coatings

    Science.gov (United States)

    Li, Wenyan; Buhrow, Jerry W.; Jolley, Scott T.; Calle, Luz M.; Hanna,Joshua S.; Rawlins, James W.

    2011-01-01

    A multifunctional smart coating for the autonomous detection, indication, and control of corrosion is been developed based on microencapsulation technology. This paper summarizes the development, optimization, and testing of microcapsules specifically designed for early detection and indication of corrosion when incorporated into a smart coating. Results from experiments designed to test the ability of the microcapsules to detect and indicate corrosion, when blended into several paint systems, show that these experimental coatings generate a color change, indicative of spot specific corrosion events, that can be observed with the naked eye within hours rather than the hundreds of hours or months typical of the standard accelerated corrosion test protocols.. Key words: smart coating, corrosion detection, microencapsulation, microcapsule, pH-sensitive microcapsule, corrosion indicator, corrosion sensing paint

  20. Method For Testing Properties Of Corrosive Lubricants

    Science.gov (United States)

    Ohi, James; De La Cruz, Jose L.; Lacey, Paul I.

    2006-01-03

    A method of testing corrosive lubricating media using a wear testing apparatus without a mechanical seal. The wear testing apparatus and methods are effective for testing volatile corrosive lubricating media under pressure and at high temperatures.

  1. Smart Coatings for Launch Site Corrosion Protection

    Science.gov (United States)

    Calle, Luz M.

    2014-01-01

    Smart, environmentally friendly paint system for early corrosion detection, mitigation, and healing that will enable supportability in KSC launch facilities and ground systems through their operational life cycles. KSC's Corrosion Technology Laboratory is developing a smart, self-healing coating that can detect and repair corrosion at an early stage. This coating is being developed using microcapsules specifically designed to deliver the contents of their core when corrosion starts.

  2. Multicomponent Oxide Systems for Corrosion Protection.

    Science.gov (United States)

    1980-11-15

    and Si(OEt) 4 are somewhat lpss corrosive to aluminum than is SiCI 4 alone, although some pitting occurs for slow hydrolysis after coating by solutions...humidity (x) 86 A𔃻 determinants of corrosion resistance. The magnesium-silicon- aluminum alloy AA 6061 is generally considered to have good corrosion ... 6061 ), the corrosion resistance exceeded that of the chromate coatings. The feasibilityof the basic approach taken here has been validated. It

  3. Surface modification for corrosion resistance

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.

    1993-06-01

    The raw gas environments that arise from coal gasification have chemical compositions that are low in pO{sub 2} and moderate-to-high in pS{sub 2}. Metallic materials for service in such an environment undergo predominantly sulfidation attack at temperatures of 400 to 700{degree}C. Modification of alloy compositions in bulk can alter the scaling processes and lead to improvements in corrosion resistance, but the benefits can only be attained at temperatures much higher than the service temperatures of the components. Modification of surfaces of structural components by several of the coating techniques examined in this study showed substantial benefit in corrosion resistance when tested in simulated coal gasification environments. The paper presents several examples of surface modification and their corrosion performance.

  4. Electrochemical corrosion of metallic biomaterials.

    Science.gov (United States)

    Pourbaix, M

    1984-05-01

    Methods of electrochemical thermodynamics (electrode potential-pH equilibrium diagrams) and electrochemical kinetics (polarization curves) may help to understand and predict the corrosion behaviour of metals and alloys in the presence of body fluids. A short review of the literature is given concerning some applications of such methods, both in vitro and in vivo, relating to surgical implants (stainless steels, chromium-cobalt-molybdenum alloys, titanium and titanium alloys) and to dental alloys (silver-tin-copper amalgams, silver-base and gold-base casting alloys, nickel-base casting alloys). Attention is drawn to the necessity of more basic research on crevice- and fretting-corrosion of surgical implant materials and dental alloys, and to the toxicity of corrosion products. A perfect understanding of the exact significance of electrode-potentials is essential for the success of such a task.

  5. Strain Measurement Technology for Corrosion Fatigue Specimen

    Institute of Scientific and Technical Information of China (English)

    ZHONG; Wei-hua; NING; Guang-sheng; ZHANG; Chang-yi; TONG; Zhen-feng; YANG; Wen

    2015-01-01

    Main pipeline is the key component of nuclear power plants(NPPs).Under the first loop water and low-cyclic load condition,the main pipeline may be induced to corrosion fatigue failure.Thus,it’s necessary to test and get the corrosion fatigue property of main pipeline material.During the corrosion fatigue test,the strain

  6. 7 CFR 2902.44 - Corrosion preventatives.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false Corrosion preventatives. 2902.44 Section 2902.44... Items § 2902.44 Corrosion preventatives. (a) Definition. Products designed to prevent the deterioration (corrosion) of metals. (b) Minimum biobased content. The preferred procurement product must have a...

  7. 49 CFR 193.2625 - Corrosion protection.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Corrosion protection. 193.2625 Section 193.2625...: FEDERAL SAFETY STANDARDS Maintenance § 193.2625 Corrosion protection. (a) Each operator shall determine which metallic components could, unless corrosion is controlled, have their integrity or...

  8. Corrosion-Induced Concrete Cracking Model Considering Corrosion-Filled Paste

    OpenAIRE

    Dong, Jianfeng; Zhao, Yuxi; Wu, Yingyao; Jin, Weiliang

    2016-01-01

    A TCP–TCL model is established to describe the relationship between the thickness of the corrosion-filled paste (CP) and that of the corrosion layer (CL). This model can describe the phenomenon that the corrosion filling in the concrete pores and accumulating at the steel/concrete interface occur synchronously. Based on the TCP–TCL model, a corrosion-induced concrete cracking model, which can quantitatively consider corrosion-filled paste at concrete/steel interface, is proposed. Combined wit...

  9. Corrosion-Inhibitor Efficiency Control: Comparison by Means of Different Portable Corrosion Rate Meters

    OpenAIRE

    Martinez Sierra, Isabel; Andrade Perdrix, Maria del Carmen; Rebolledo Ramos, Nuria; Luo, L; De Schutter, G

    2010-01-01

    Corrosion-inhibiting substances have been applied to suppress corrosion mainly on bare steel, but when corrosion is progressing, suppression can be achieved if anodic and cathodic reactions are avoided, which is not an easy objective, particularly if the bare metal is surrounded by concrete. In the present article, several corrosion inhibitors are studied to identify their inhibition efficiency in concrete. The percentage of reduction of the corrosion rate without and with inhibitor is named ...

  10. Electrochemical Measurement of Atmospheric Corrosion

    Science.gov (United States)

    DeArmond, Anna H.; Davis, Dennis D.; Beeson, Harold D.

    1999-01-01

    Corrosion of Shuttle thruster components in atmospheres containing high concentrations of nitrogen tetroxide (NTO) and water is an important issue in ground operations of bipropellant systems in humid locations. Measurements of the corrosivities of NTO-containing atmospheres and the responses of different materials to these atmospheres have been accomplished using an electrochemical sensor. The sensor is composed of alternating aluminum/titanium strips separated by thin insulating layers. Under high humidity conditions a thin film of water covers the surface of the sensor. Added NTO vapor reacts with the water film to form a conductive medium and establishes a galvanic cell. The current from this cell can be integrated with respect to time and related to the corrosion activity. The surface layer formed from humid air/NTO reacts in the same way as an aqueous solution of nitric acid. Nitric acid is generally considered an important agent in NTO corrosion situations. The aluminum/titanium sensor is unresponsive to dry air, responds slightly to humid air (> 75% RH), and responds strongly to the combination of humid air and NTO. The sensor response is a power function (n = 2) of the NTO concentration. The sensor does not respond to NTO in dry air. The response of other materials in this type of sensor is related to position of the material in a galvanic series in aqueous nitric acid. The concept and operation of this electrochemical corrosion measurement is being applied to other corrosive atmospheric contaminants such as hydrogen chloride, hydrogen fluoride, sulfur dioxide, and acidic aerosols.

  11. Corrosion performance of structural alloys.

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.

    1999-07-15

    Component reliability and long-term trouble-free performance of structural materials are essential in power-generating and gasification processes that utilize coal as a feedstock. During combustion and conversion of coal, the environments encompass a wide range of oxygen partial pressures, from excess-air conditions in conventional boilers to air-deficient conditions in 10W-NO{sub x} and gasification systems. Apart from the environmental aspects of the effluent from coal combustion and conversion, one concern from the systems standpoint is the aggressiveness of the gaseous/deposit environment toward structural components such as waterwall tubes, steam superheaters, syngas coolers, and hot-gas filters. The corrosion tests in the program described in this paper address the individual and combined effects of oxygen, sulfur, and chlorine on the corrosion response of several ASME-coded and noncoded structural alloys that were exposed to air-deficient and excess-air environments typical of coal-combustion and gasification processes. Data in this paper address the effects of preoxidation on the subsequent corrosion performance of structural materials such as 9Cr-1Mo ferritic steel, Type 347 austenitic stainless steel, Alloys 800, 825, 625, 214, Hastelloy X, and iron aluminide when exposed at 650 C to various mixed-gas environments with and without HCI. Results are presented for scaling kinetics, microstructural characteristics of corrosion products, detailed evaluations of near-surface regions of the exposed specimens, gains in our mechanistic understanding of the roles of S and Cl in the corrosion process, and the effect of preoxidation on subsequent corrosion.

  12. Cyclone reburning retrofit: Corrosion evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Sarv, H.; Paul, L.D. (Babcock and Wilcox Co., New Orleans, LA (USA))

    1991-01-01

    Reburning is an emerging NO{sub x} reducing technology which offers cyclone boiler owners a promising alternative to the more expensive flue gas cleanup techniques. Pilot-scale test results have shown that the corrosive H{sub 2}S gas can evolve during reburn. This can pose a potential problem and concern in retrofits burning high-sulfur Illinois coals. This research program is intended to assess tube corrosion under simulated reburning conditions (temperature, stoichiometry, and H{sub 2}S concentration). Performance of existing carbon steel as well as other alloys will be tested and compared. 1 fig.

  13. Cyclone reburning retrofit: Corrosion evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Farzan, H.; Paul, L.D. (Babcock and Wilcox Co., New Orleans, LA (USA))

    1990-01-01

    Reburning is an emerging NO{sub x} reducing technology which offers cyclone boiler owners a promising alternative to the more expensive flue gas cleanup techniques. Pilot-scale test results have shown that the corrosive H{sub 2}S gas can evolve during reburn. This can pose a potential problem and concern in retrofits burning high-sulfur Illinois coals. This research program is intended to assess tube corrosion under simulated reburning conditions (temperature, stoichiometry, and H{sub 2}S concentration). Performance of existing carbon steel as well as other alloys will be tested and compared. 1 fig.

  14. Corrosion Reliability of Electronic Systems

    DEFF Research Database (Denmark)

    Ambat, Rajan; Jensen, Stine G.; Møller, Per

    2008-01-01

    Inherently two factors namely multi-material usage and potential bias makes electronic devices susceptible to corrosion if exposed to humid conditions. The problem is compounded today due to miniaturization and contamination effects. The reduction in size of the components and close spacing...... on a Printed Circuit Board (PCB) for high density packing has greatly increased the risk of corrosion under humid conditions. An important issue is the failures due to electrolytic metal migration. This paper describes an investigation of the electrolytic migration of Sn-Pb solder lines on PCBs in humid...

  15. Microbial Influenced Corrosion (MIC) Study

    Science.gov (United States)

    2012-05-23

    low lying areas breaks down protective coating system and causes structural corrosion , • Water and organic/inorganic nutrients BUSINESS SENSITIVE...Chemical disinfection (T.O 1-1-8 and T.O 1-1-691) • Biocidal rinses and coatings • Biocidal Corrosion Preventative Compounds or CPCs BUSINESS...Type: H    Proprietary  Coating  w/ Silver  Inhibitor   Non‐Chrome Treatment + Mg‐Rich  Primer  Coupon Type: I    Prekote® (Pantheon Chemical) N/A

  16. High temperature corrosion in gasifiers

    Directory of Open Access Journals (Sweden)

    Bakker Wate

    2004-01-01

    Full Text Available Several commercial scale coal gasification combined cycle power plants have been built and successfully operated during the last 5-10 years. Supporting research on materials of construction has been carried out for the last 20 years by EPRI and others. Emphasis was on metallic alloys for heat exchangers and other components in contact with hot corrosive gases at high temperatures. In this paper major high temperature corrosion mechanisms, materials performance in presently operating gasifiers and future research needs will be discussed.

  17. Corrosive effects of hvdc transmission

    Energy Technology Data Exchange (ETDEWEB)

    Cornwell, F.E.; Backstrom, T.E.

    1966-02-01

    Field tests using ac transmission lines for introduction of direct current into the earth at widely separated points are described. One test circuit was between a Tracy pumping plant and a Shasta power plant in California, and two others were in the Hoover power plant area. Evaluation of the effects of such ground currents on corrosion of buried metalwork was a primary aim of the tests. Potential gradients, pipe-to-soil potentials, and soil resistivities are discussed in detail. Estimates are made of the distances from ehv dc terminal installations within which corrosion prevention procedures may become necessary.

  18. Coatings for improved corrosion resistance

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.

    1992-05-01

    Several coating approaches are being developed to resist attack in coal-fired environments and thereby minimize corrosion of underlying substrate alloys and extend the time for onset of breakaway corrosion. In general, coating systems can be classified as either diffusion or overlay type, which are distinguished principally by the method of deposition and the structure of the resultant coating-substrate bond. The coating techniques examined are pack cementation, electrospark deposition, physical and chemical vapor deposition, plasma spray, and ion implantation. In addition, ceramic coatings are used in some applications.

  19. Double Xp11.22 deletion including SHROOM4 and CLCN5 associated with severe psychomotor retardation and Dent disease.

    Science.gov (United States)

    Armanet, Narjes; Metay, Corinne; Brisset, Sophie; Deschenes, Georges; Pineau, Dominique; Petit, François M; Di Rocco, Federico; Goossens, Michel; Tachdjian, Gérard; Labrune, Philippe; Tosca, Lucie

    2015-01-01

    Here we report the clinical and molecular characterization of two Xp11.22 deletions including SHROOM4 and CLCN5 genes. These deletions appeared in the same X chromosome of the same patient. The patient is a six-year-old boy who presented hydrocephalus, severe psychomotor and growth retardation, facial dysmorphism and renal proximal tubulopathy associated with low-molecular-weight proteinuria, hypercalciuria, hyperaminoaciduria, hypophosphatemia and hyperuricemia. Standard and high resolution karyotypes showed a 46,XY formula. Array-CGH revealed two consecutive cryptic deletions in the region Xp11.22, measuring respectively 148 Kb and 2.6 Mb. The two deletions were inherited from the asymptomatic mother. Array-CGH allowed us to determine candidate genes in the deleted region. The disruption and partial loss of CLCN5 confirmed the diagnostic of Dent disease for this patient. Moreover, the previously described involvement of SHROOM4 in neuronal development is discussed.

  20. A Multifunctional Coating for Autonomous Corrosion Control

    Science.gov (United States)

    Calle, L. M.; Hintze, P. E.; Li, W.; Buhrow, J. W.; Jolley, S. T.

    2011-01-01

    This slide presentation reviews the effects of corrosion on various structures at the Kennedy Space Center, and the work to discover a corrosion control coating that will be autonomous and will indicate corrosion at an early point in the process. Kennedy Space Center has many environmental conditions that are corrosive: ocean salt spray, heat, humidity, sunlight and acidic exhaust from the Solid Rocket Boosters (SRBs). Presented is a chart which shows the corrosion rates of carbon steel at various locations. KSC has the highest corrosion rates with 42.0 mils/yr, leading the next highest Galeta Point Beach, in the Panama Canal Zone with 27 mils/yr corrosion. A chart shows the changes in corrosion rate with the distance from the ocean. The three types of corrosion protective coatings are described: barrier (passive), Barrier plus active corrosion inhibiting components, and smart. A smart coating will detect and respond actively to changes in its environment in a functional and predictable manner and is capable of adapting its properties dynamically. The smart coating uses microcapsules, particles or liquid drops coated in polymers, that can detect and control the corrosion caused by the environment. The mechanism for a pH sensitive microcapsule and the hydrophobic core microcapsule are demonstrated and the chemistry is reviewed. When corrosion begins, the microcapsule will release the contents of the core (indicator, inhibitor, and self healing agent) in close proximity to the corrosion. The response to a pH increase is demonstrated by a series of pictures that show the breakdown of the microcapsule and the contents release. An example of bolt corrosion is used, as an example of corrosion in places that are difficult to ascertain. A comparison of various coating systems is shown.

  1. Planejamento radiográfico e tomográfico para instalação de implantes dentários

    Directory of Open Access Journals (Sweden)

    Cauê Monteiro dos Santos

    2014-06-01

    Full Text Available Normal 0 21 false false false PT-BR X-NONE X-NONE O sucesso do tratamento com implantes dentários está relacionado diretamente com o planejamento correto para instalação do mesmo. Inserido neste contexto de planejamento para instalação de implantes dentários, a avaliação radiográfica e tomográfica se mostram como uma das mais importantes etapas. As radiografias e tomografias possibilitam o estudo das áreas anatômicas que precisam ser respeitadas no ato cirúrgico e oferecem subsídios para se estudar os sítios teciduais que receberão os diversos tipos de implantes dentários. Este trabalho tem como objetivo realizar uma revisão de literatura sobre planejamento radiográfico e tomográfico para instalação de implantes dentários, buscando mostrar a modalidade de imagem ideal para tal procedimento

  2. Preferências por alimentos doces e cárie dentária em pré-escolares

    Directory of Open Access Journals (Sweden)

    Tomita Nilce E

    1999-01-01

    Full Text Available OBJETIVO: Avaliar as preferências pelo sabor doce e sua associação com as condições socioeconômicas e a prevalência de cárie dentária em pré-escolares. MÉTODOS: A amostra foi composta por 572 crianças de 4 a 6 anos, matriculadas em pré-escolas, dividida em estratos socioeconômicos segundo a procedência (um bairro central, um periférico e Programa de Desfavelamento. Estudo transversal, foi desenvolvido em duas etapas. A preferência pelo sabor doce foi avaliada através do Sweet Preference Inventory modificado. A concentração das soluções variou de 0 a 400 g/litro (0 a 1,17 molar. Foi utilizado o índice ceos para verificar a prevalência de cárie. RESULTADOS: Foram encontradas diferenças estatisticamente significantes entre as crianças do Programa de Desfavelamento e dos demais grupos na preferência pelo sabor doce e no consumo de açúcar, bem como associação entre a procedência e o percentual de crianças livres de cárie, sendo o grupo do Desfavelamento o menos favorecido (p<0,05. CONCLUSÃO: Os achados sustentam a hipótese de que o nível socioeconômico influencia a preferência por açúcar e esta, por sua vez, está associada à prevalência de cárie dentária na dentição decídua.

  3. Intrusão dentária utilizando mini-implantes Orthodontic intrusion with mini-implant anchorage

    Directory of Open Access Journals (Sweden)

    Telma Martins de Araújo

    2008-10-01

    Full Text Available INTRODUÇÃO: dentre os diversos tipos de movimentos dentários induzidos ortodonticamente, o de intrusão é, sem dúvida, um dos mais difíceis de serem conseguidos. A mecânica intrusiva convencional, apesar de viável, é complexa, no que diz respeito ao controle de seus efeitos colaterais. Isso, em grande parte, refere-se à dificuldade em se obter uma ancoragem satisfatória. Neste contexto, os mini-implantes, por oferecerem efetiva ancoragem esquelética, têm se mostrado de extrema valia para os ortodontistas, tornando a intrusão, tanto de dentes anteriores quanto posteriores, um procedimento cada vez mais simples, do ponto de vista mecânico. OBJETIVO: pretende-se, então, neste artigo, descrever e demonstrar, clinicamente, as diversas possibilidades de utilização dos mini-implantes como recurso de ancoragem para o movimento de intrusão.INTRODUCTION: Among all different varieties of orthodontically induced tooth movement, intrusion is, without doubt, one of the most difficult movements to be reached. Conventional intrusive biomechanics, although possible, may lead to undesirable side-effects. These events, in most cases, are related to the difficulty in obtaining an efficient anchorage unit. Then, mini-implants, because of their high success rates of effective skeletal anchorage, are valuable devices to orthodontists, transforming the intrusion movement, both at the anterior and the posterior regions, a more and more uncomplicated biomechanical procedure. AIM: to describe and show, clinically, different ways of using mini-implants as an anchorage system to intrusion movement.

  4. Assessing Level and Effectiveness of Corrosion Education in the UAE

    Directory of Open Access Journals (Sweden)

    Hwee Ling Lim

    2012-01-01

    Full Text Available The consequences of corrosion can be minimized by an engineering workforce well trained in corrosion fundamentals and management. Since the United Arab Emirates incurs the second highest cost of corrosion after Saudi Arabia, this paper examined the quality of corrosion education in the UAE. Surveys with academia and industry respondents showed that dedicated corrosion courses and engineering courses that integrated corrosion into the curricula were available in UAE universities, but graduates had insufficient knowledge of corrosion engineering and superficial understanding of corrosion in real-life design contexts. The effectiveness of corrosion education is determined by both competence in corrosion knowledge/skills and availability of resources (faculty and research. Though most departments would not hire new corrosion-specialist faculty, department research efforts and industry partnerships in corrosion research were present. The paper concluded with recommendations for improving knowledge and skills of future engineers in corrosion and enhancing corrosion instruction to better meet industry needs.

  5. General Corrosion and Localized Corrosion of Waste Package Outer Barrier

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J.C.; McCright, R.D.

    2000-01-28

    Alloy 22 is an extremely Corrosion Resistant Material, with a very stable passive film. Based upon exposures in the LTCTF, the GC rates of Alloy 22 are typically below the level of detection, with four outliers having reported rates up to 0.75 #mu#m per year. In any event, over the 10,000 year life of the repository, GC of the Alloy 22 (assumed to be 2 cm thick) should not be life limiting. Because measured corrosion potentials are far below threshold potentials, localized breakdown of the passive film is unlikely under plausible conditions, even in SSW at 120 deg C. The pH in ambient-temperature crevices formed from Alloy 22 have been determined experimentally, with only modest lowering of the crevice pH observed under plausible conditions. Extreme lowering of the crevice pH was only observed under situations where the applied potential at the crevice mouth was sufficient to result in catastrophic breakdown of the passive film above the threshold potential in non-buffered conditions not characteristic of the Yucca Mountain environment. In cases where naturally ocurring buffers are present in the crevice solution, little or no lowering of the pH was observed, even with significant applied potential. With exposures of twelve months, no evidence of crevice corrosion has been observed in SDW, SCW and SAW at temperatures up to 90 deg C. An abstracted model has been presented, with parameters determined experimentally, that should enable performance assessment to account for the general and localized corrosion of this material. A feature of this model is the use of the materials specification to limit the range of corrosion and threshold potentials, thereby making sure that substandard materials prone to localized attack are avoided. Model validation will be covered in part by a companion SMR on abstraction of this model.

  6. Atmospheric corrosion sensor based on strain measurement

    Science.gov (United States)

    Kasai, Naoya; Hiroki, Masatoshi; Yamada, Toshirou; Kihira, Hiroshi; Matsuoka, Kazumi; Kuriyama, Yukihisa; Okazaki, Shinji

    2017-01-01

    In this paper, an in situ atmospheric corrosion sensor based on strain measurement is discussed. The theoretical background for measuring the reduction in thickness of low carbon steel is also presented. Based on the theoretical considerations, a test piece and apparatus for an atmospheric corrosion sensor were designed. Furthermore, in a dry–wet cyclic accelerated exposure experiment, the measured strain indicated thinning of the test piece, although the corrosion product generated on the surface of the test piece affected the results. The atmospheric corrosion sensor would be effective for evaluating atmospheric corrosion of many types of infrastructure.

  7. Nodular Corrosion Characteristics of Zirconium Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun Gil; Jeong, Y. H.; Park, S. Y.; Lee, D. J

    2003-01-15

    This study was reported the effect of the nodular corrosion on the nuclear reactor environmental along with metallurgical influence, also suggested experimental scheme related to evaluate nodular corrosion characteristics of Zr-1 Nb alloy. Remedial strategies against the nodular corrosion should firstly develop plan to assess the effect of the water quality condition (Oxygen, Hydrogen) as well as the boiling on the nodular corrosion, secondarily establish plan to control heat treatment process to keep a good resistance on nodular corrosion in Zr-1Nb alloy as former western reactor did.

  8. Analyses of containment structures with corrosion damage

    Energy Technology Data Exchange (ETDEWEB)

    Cherry, J.L.

    1996-12-31

    Corrosion damage to a nuclear power plant containment structure can degrade the pressure capacity of the vessel. For the low-carbon, low- strength steels used in containments, the effect of corrosion on material properties is discussed. Strain-to-failure tests, in uniaxial tension, have been performed on corroded material samples. Results were used to select strain-based failure criteria for corroded steel. Using the ABAQUS finite element analysis code, the capacity of a typical PWR Ice Condenser containment with corrosion damage has been studied. Multiple analyses were performed with the locations of the corrosion the containment, and the amount of corrosion varied in each analysis.

  9. Urgências em traumatismos dentários: classificação, características e procedimentos Dental traumatism urgencies: classification, signs and procedures

    Directory of Open Access Journals (Sweden)

    Mariane Emi Sanabe

    2009-12-01

    Full Text Available OBJETIVO: Discutir os aspectos das urgências odontológicas relacionadas aos traumatismos dentários, disponibilizando mais informações para médicos pediatras ou plantonistas de serviços de atendimento de urgências e emergências. FONTES DE DADOS: O levantamento dos dados foi realizado na base de dados Pubmed e Bireme, selecionando os artigos dos últimos 13 anos. As palavras-chave utilizadas foram: traumatismo dentário, dente decíduo e dente permanente. Os critérios de inclusão utilizados foram: artigos em inglês e português sobre incidência, prevalência e etiologia, guias de procedimentos e casos clínicos apenas de traumatismo dentário, sendo excluídos artigos de clareamento de dentes traumatizados, traumas faciais ósseos e casos clínicos de acompanhamento reduzido. SÍNTESE DOS DADOS: Os dados foram descritos de forma concisa para se tornar um guia de fácil leitura e rápido acesso em relação à conduta, necessidade de atendimento imediato e correta escolha de soluções para armazenagem dos dentes e fragmentos. CONCLUSÕES: O conhecimento sobre o assunto, a agilidade no tratamento de urgência e o correto encaminhamento do paciente proporcionam melhor prognóstico.OBJECTIVE: The aim of this literature review is to discuss the clinical aspects of dental urgencies related to dental traumatisms, providing more information for health professionals who work in emergency units, such as pediatricians or physicians on-call and nurses. DATA SOURCE: The studies were searched and selected in the Pubmed and Bireme databases, from the past 13 years. The keywords were: tooth injuries, deciduous tooth and permanent tooth. The inclusion criteria were: articles written in English and Portuguese related to incidence, prevalence, cause, guidelines and case reports of dental traumatism. Studies about dental bleaching in dental trauma, face bone trauma and reduced post-operative case reports were excluded. DATA SYNTHESIS: The data were

  10. O conceito de reabsorções dentárias ou As reabsorções dentárias não são multifatoriais, nem complexas, controvertidas ou polêmicas! The concept of root resorptions: root resorptions are not multifactorial, complex, controversial or polemical!

    Directory of Open Access Journals (Sweden)

    Alberto Consolaro

    2011-08-01

    Full Text Available Os mecanismos das reabsorções dentárias são conhecidos e suas causas bem definidas. Clinicamente são assintomáticas e não induzem alterações pulpares, periapicais e periodontais, sendo geralmente consequências delas. As reabsorções dentárias são alterações locais e adquiridas e não representam manifestações dentárias de doenças sistêmicas. As reabsorções dentárias ocorrem quando as estruturas de proteção dos dentes em relação à remodelação óssea são eliminados, especialmente os cementoblastos e restos epiteliais de Malassez.The mechanisms of root resorptions are known, and their causes are well defined. They are clinically asymptomatic and do not induce pulp, periapical or periodontal changes; rather, they are usually consequences of these phenomena. Root resorptions are local and acquired defects, and not dental signs of systemic diseases. Root resorptions occur when structures that protect teeth from bone remodeling, particularly cementoblasts and epithelial rests of Malassez, are eliminated.

  11. Corrosion of Metal-Matrix Composites with Aluminium Alloy Substrate

    Directory of Open Access Journals (Sweden)

    B. Bobic

    2010-03-01

    Full Text Available The corrosion behaviour of MMCs with aluminium alloy matrix was presented. The corrosion characteristics of boron-, graphite-, silicon carbide-, alumina- and mica- reinforced aluminium MMCs were reviewed. The reinforcing phase influence on MMCs corrosion rate as well as on various corrosion forms (galvanic, pitting, stress corrosion cracking, corrosion fatique, tribocorrosion was discussed. Some corrosion protection methods of aluminium based MMCs were described

  12. The dual role of microbes in corrosion.

    Science.gov (United States)

    Kip, Nardy; van Veen, Johannes A

    2015-03-01

    Corrosion is the result of a series of chemical, physical and (micro) biological processes leading to the deterioration of materials such as steel and stone. It is a world-wide problem with great societal and economic consequences. Current corrosion control strategies based on chemically produced products are under increasing pressure of stringent environmental regulations. Furthermore, they are rather inefficient. Therefore, there is an urgent need for environmentally friendly and sustainable corrosion control strategies. The mechanisms of microbially influenced corrosion and microbially influenced corrosion inhibition are not completely understood, because they cannot be linked to a single biochemical reaction or specific microbial species or groups. Corrosion is influenced by the complex processes of different microorganisms performing different electrochemical reactions and secreting proteins and metabolites that can have secondary effects. Information on the identity and role of microbial communities that are related to corrosion and corrosion inhibition in different materials and in different environments is scarce. As some microorganisms are able to both cause and inhibit corrosion, we pay particular interest to their potential role as corrosion-controlling agents. We show interesting interfaces in which scientists from different disciplines such as microbiology, engineering and art conservation can collaborate to find solutions to the problems caused by corrosion.

  13. The dual role of microbes in corrosion

    Science.gov (United States)

    Kip, Nardy; van Veen, Johannes A

    2015-01-01

    Corrosion is the result of a series of chemical, physical and (micro) biological processes leading to the deterioration of materials such as steel and stone. It is a world-wide problem with great societal and economic consequences. Current corrosion control strategies based on chemically produced products are under increasing pressure of stringent environmental regulations. Furthermore, they are rather inefficient. Therefore, there is an urgent need for environmentally friendly and sustainable corrosion control strategies. The mechanisms of microbially influenced corrosion and microbially influenced corrosion inhibition are not completely understood, because they cannot be linked to a single biochemical reaction or specific microbial species or groups. Corrosion is influenced by the complex processes of different microorganisms performing different electrochemical reactions and secreting proteins and metabolites that can have secondary effects. Information on the identity and role of microbial communities that are related to corrosion and corrosion inhibition in different materials and in different environments is scarce. As some microorganisms are able to both cause and inhibit corrosion, we pay particular interest to their potential role as corrosion-controlling agents. We show interesting interfaces in which scientists from different disciplines such as microbiology, engineering and art conservation can collaborate to find solutions to the problems caused by corrosion. PMID:25259571

  14. Corrosion resistant metallic bipolar plate

    Science.gov (United States)

    Brady, Michael P.; Schneibel, Joachim H.; Pint, Bruce A.; Maziasz, Philip J.

    2007-05-01

    A corrosion resistant, electrically conductive component such as a bipolar plate for a PEM fuel cell includes 20 55% Cr, balance base metal such as Ni, Fe, or Co, the component having thereon a substantially external, continuous layer of chromium nitride.

  15. CORROSION INHIBITOR FOR CARBON STEELS

    African Journals Online (AJOL)

    corrosion inhibitor for carbon steel in 3% ac]neon.s' NaCl solution (pH 6) ... compared to stainless steels (Buchweishaija & Hagen 1997). Organic compounds are ... resistant dust for break and clutch linings, wood binders and mould (Gedam.

  16. Encapsulated Multifunction Corrosion Inhibitive Primer.

    Science.gov (United States)

    1983-11-01

    Tec #19 (alkaline detergent), scrubbed vigorously with cheese cloth, then perform R.I.A. drop test for cleanliness (ASTM 7.1.6.22) (Turco Air Tec...Systems, DOE/NASA TM-78180 (1978). 39. Gouda , V.K. and Shater, M.A., Corrosion Sci. 15 199 (1975). 40. Controlled release, Pesticide Symposium 41

  17. Corrosion inhibition for distillation apparatus

    Science.gov (United States)

    Baumert, Kenneth L.; Sagues, Alberto A.; Davis, Burtron H.; Schweighardt, Frank K.

    1985-01-01

    Tower material corrosion in an atmospheric or sub-atmospheric distillation tower in a coal liquefaction process is reduced or eliminated by subjecting chloride-containing tray contents to an appropriate ion-exchange resin to remove chloride from such tray contents materials.

  18. CORROSION RESISTANT JACKETED METAL BODY

    Science.gov (United States)

    Brugmann, E.W.

    1958-08-26

    Reactor faul elements of the elongated cylindrical type which are jacketed in a corrosion resistant material are described. Each feel element is comprised of a plurality of jacketed cylinders of fissionable material in end to end abutting relationship, the jackets being welded together at their adjoining ends to retain the individual segments together and seat the interior of the jackets.

  19. Evolutionary Computation Techniques for Predicting Atmospheric Corrosion

    Directory of Open Access Journals (Sweden)

    Amine Marref

    2013-01-01

    Full Text Available Corrosion occurs in many engineering structures such as bridges, pipelines, and refineries and leads to the destruction of materials in a gradual manner and thus shortening their lifespan. It is therefore crucial to assess the structural integrity of engineering structures which are approaching or exceeding their designed lifespan in order to ensure their correct functioning, for example, carrying ability and safety. An understanding of corrosion and an ability to predict corrosion rate of a material in a particular environment plays a vital role in evaluating the residual life of the material. In this paper we investigate the use of genetic programming and genetic algorithms in the derivation of corrosion-rate expressions for steel and zinc. Genetic programming is used to automatically evolve corrosion-rate expressions while a genetic algorithm is used to evolve the parameters of an already engineered corrosion-rate expression. We show that both evolutionary techniques yield corrosion-rate expressions that have good accuracy.

  20. Corrosion Rate Monitoring in District Heating Systems

    DEFF Research Database (Denmark)

    Hilbert, Lisbeth Rischel; Nielsen, Lars Vendelbo; Andersen, A.

    2005-01-01

    Quality control in district heating systems to keep uniform corrosion rates low and localized corrosion minimal is based on water quality control. Side-stream units equipped with carbon steel probes for online monitoring were mounted in district heating plants to investigate which techniques would...... be applicable, and if on-line monitoring could improve the quality control. Water quality monitoring was applied as well as corrosion rate monitoring with linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS), electrical resistance (ER) technique, mass loss and a crevice corrosion...... cell for localized corrosion risk estimation. Important variations in corrosion rate due to changes in make-up water quality were detected with the continuous monitoring provided by ER and crevice cell, while LPR gave unreliable corrosion rates. The acquisition time of two-three days for EIS...

  1. Corrosion Rate Monitoring in District Heating Systems

    DEFF Research Database (Denmark)

    Hilbert, Lisbeth Rischel; Nielsen, Lars Vendelbo; Andersen, A.

    2005-01-01

    Quality control in district heating systems to keep uniform corrosion rates low and localized corrosion minimal is based on water quality control. Side-stream units equipped with carbon steel probes for online monitoring were mounted in district heating plants to investigate which techniques would...... be applicable, and if on-line monitoring could improve the quality control. Water quality monitoring was applied as well as corrosion rate monitoring with linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS), electrical resistance (ER) technique, mass loss and a crevice corrosion...... cell for localized corrosion risk estimation. Important variations in corrosion rate due to changes in make-up water quality were detected with the continuous monitoring provided by ER and crevice cell, while LPR gave unreliable corrosion rates. The acquisition time of two-three days for EIS...

  2. Effect of corrosion on flexural bond strength

    Directory of Open Access Journals (Sweden)

    Akshatha Shetty

    2014-09-01

    Full Text Available Corrosion is one of the main causes affecting durability of structures. Corrosion effects on structures cannot be ignored and replaced. To understand the performance of structures there is a need to study the rate at which different corrosion levels occur. Hence the present investigation has been taken up to study the behaviour of NBS (National Bureau of Standard beam specimens made up of Ordinary Portland Cement (OPC and Portland Pozzolona Cement (PPC concrete matrix were subjected to accelerated corrosion for different corrosion levels of 2.5 % to 10 % at 2.5 % interval. Results are compared with those for control beam specimen. It is observed that bond stress value decreases with the increase in corrosion levels. Also corrosion leads to the decline of load carrying capacity.

  3. High Temperature Corrosion on Biodust Firing

    DEFF Research Database (Denmark)

    Okoro, Sunday Chukwudi

    The high content of alkali metals and chlorine in biomass gives rise to fouling/slagging and corrosion of heat exchange components, such as superheaters, in biomass fired power plants. Increasing the lifetime of these components, and in addition, preventing unwarranted plant shutdowns due...... to their failure, requires understanding of the complex corrosion mechanisms, as well as development of materials that are resistant to corrosion under biomass firing conditions, thereby motivating the current work. To understand the mechanisms of corrosion attack, comprehensive analysis of corrosion products...... was necessary. In the present work, two complementary methodologies based on analysis of cross sections and plan views were applied to achieve comprehensive characterization of corrosion products. The suitability of these methods for both laboratory scale and full scale corrosion investigations was demonstrated...

  4. NASA's Corrosion Technology Laboratory at the Kennedy Space Center: Anticipating, Managing, and Preventing Corrosion

    Science.gov (United States)

    Calle, Luz Marina

    2015-01-01

    The marine environment at NASAs Kennedy Space Center (KSC) has been documented by ASM International (formerly American Society for Metals) as the most corrosive in North America. With the introduction of the Space Shuttle in 1981, the already highly corrosive conditions at the launch pads were rendered even more severe by the highly corrosive hydrochloric acid (HCl) generated by the solid rocket boosters (SRBs). Numerous failures at the launch pads are caused by corrosion. The structural integrity of ground infrastructure and flight hardware is critical to the success, safety, cost, and sustainability of space missions. NASA has over fifty years of experience dealing with unexpected failures caused by corrosion and has developed expertise in corrosion control in the launch and other environments. The Corrosion Technology Laboratory at KSC evolved, from what started as an atmospheric exposure test site near NASAs launch pads, into a capability that provides technical innovations and engineering services in all areas of corrosion for NASA, external partners, and customers.This paper provides a chronological overview of NASAs role in anticipating, managing, and preventing corrosion in highly corrosive environments. One important challenge in managing and preventing corrosion involves the detrimental impact on humans and the environment of what have been very effective corrosion control strategies. This challenge has motivated the development of new corrosion control technologies that are more effective and environmentally friendly. Strategies for improved corrosion protection and durability can have a huge impact on the economic sustainability of human spaceflight operations.

  5. Titanium corrosion in alkaline hydrogen peroxide environments

    Science.gov (United States)

    Been, Jantje

    1998-12-01

    The corrosion of Grade 2 titanium in alkaline hydrogen peroxide environments has been studied by weight loss corrosion tests, electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) measurements and potentiodynamic polarography. Calcium ions and wood pulp were investigated as corrosion inhibitors. In alkaline peroxide, the titanium corrosion rate increased with increasing pH, temperature, and hydrogen peroxide concentration. The corrosion controlling mechanism is thought to be the reaction of the oxide with the perhydroxyl ion. No evidence of thermodynamically stable calcium titanate was found in the surface film of test coupons exposed to calcium-inhibited alkaline peroxide solutions. Calcium inhibition is probably the result of low local alkali and peroxide concentrations at the metal surface produced by reaction of adsorbed calcium with hydrogen peroxide. It has been shown that the inhibiting effect of calcium is temporary, possibly through an effect of calcium on the chemical and/or physical stability of the surface oxide. Pulp is an effective and stable corrosion inhibitor. Raising the pulp concentration decreased the corrosion rate. The inhibiting effect of pulp may be related to the adsorption and interaction of the pulp fibers with H 2O2, thereby decreasing the peroxide concentration and rendering the solution less corrosive. The presence of both pulp and calcium led to higher corrosion rates than obtained by either one inhibitor alone. Replacement of hydrofluoric acid with alkaline peroxide for pickling of titanium was investigated. Titanium corrosion rates in alkaline peroxide exceeded those obtained in the conventional hydrofluoric acid bath. General corrosion was observed with extensive roughening of the surface giving a dull gray appearance. Preferred dissolution of certain crystallographic planes was investigated through the corrosion of a titanium single crystal. Whereas the overall effect on the corrosion rate was small

  6. Decisão pela extração dentária e incidência de cáries e perdas dentárias em idosos da coorte de Carlos Barbosa, RS : perspectivas qualitativa e quantitativa

    OpenAIRE

    2012-01-01

    Introdução: A perda dentária e o edentulismo podem afetar de maneira significativa a saúde bucal e a saúde geral, a qualidade de vida, e a nutrição de idosos. A cárie e a perda dentária têm sido descritas como o resultado de processos que envolvem elementos biológicos, nas superfícies dentárias, e de uma combinação de fatores comportamentais e sociais. Além disso, o contexto histórico no qual os indivíduos estão inseridos influencia seus comportamentos e percepções em relação à saúde bucal. U...

  7. Corrosion inhibition of a hygroscopic inorganic dust-depressor

    Institute of Scientific and Technical Information of China (English)

    Longzhe Jin; Lu Wang; Dongke Chen

    2006-01-01

    Metallic corrosion is a serious problem in the application of a hygroscopic inorganic dust-depressor. The basic characteristics of a hygroscopic inorganic dust-depressor and its corrosivity, corrosion mechanism, as well as the principle of corrosion inhibition were analyzed. The static mass-loss test was carried out to investigate the corrosion behavior and the effect of the dustdepressor. The static corrosion rates of steel specimens were measured in six different corrosion inhibitor solutions of the dustdepressor, and the suitable corrosion inhibitors for the dust-depressor to reduce the corrosivity were found out.

  8. Microencapsulation Technology for Corrosion Mitigation by Smart Coatings

    Science.gov (United States)

    Buhrow, Jerry; Li, Wenyan; Jolley, Scott; Calle, Luz M.

    2011-01-01

    A multifunctional, smart coating for the autonomous control of corrosion is being developed based on micro-encapsulation technology. Corrosion indicators as well as corrosion inhibitors have been incorporated into microcapsules, blended into several paint systems, and tested for corrosion detection and protection effectiveness. This paper summarizes the development, optimization, and testing of microcapsules specifically designed to be incorporated into a smart coating that will deliver corrosion inhibitors to mitigate corrosion autonomously. Key words: smart coating, corrosion inhibition, microencapsulation, microcapsule, pH sensitive microcapsule, corrosion inhibitor, corrosion protection pain

  9. Electrochemical characterisation speeds up prediction of corrosion behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Schuring, E.W.; Hooijmans, J.W. [ECN Environment and Energy Engineering, Petten (Netherlands)

    2013-04-15

    The contents of this presentation show the following elements: Introduction; Corrosion in real life; Why Electrochemical characterisation of corrosion; Applications (corrosion resistance coatings, corrosion behaviour (brazed) joints); Available electrochemical corrosion techniques; Standards; Conclusions. In the Conclusions the corrosion screening method is summarized: ECN method fast; within 1h -1 week results depending on test method; Fast pre-selection of promising materials/combinations (cost savings); Determining of corrosion initiation; Determination of corrosion mechanisms and propagation; Life time predictions possible; Strong combination with metallographic post-investigation; Ranking materials / constructions for corrosion performance.

  10. INTERNAL CORROSION MONITORING IN OFFSHORE PLATFORMS

    Directory of Open Access Journals (Sweden)

    Fernando Benedicto Mainier

    2008-08-01

    Full Text Available Corrosion is one of the main causes of failures in equipment and pipes in off-shore oil production. These failures harm the process, slow the production operational chronogram, and generate high costs of maintenance, beyond generation risks to health and environment. Due to the fact that most of the equipment, tubing and pipes of production platforms are made of steel, in general, carbon steel, the industry of petroleum exploration will always coexist with the corrosive process. The use of a Corrosion Monitoring Plan to diagnostic, to control and to manage the evolution of corrosives process in off-shore oil platforms is the strategy proposed in this work to prevent problems as described above. The Internal Corrosion Monitoring Plan (ICMP, is based on lab analysis of the corrosively of fluids and residues showed periodically in off-shore operational platform; in the corrosion rate determined by the periodic use of test bodies installed inside off-shore oil platforms tubing systems, as mass loss coupons and electric resistance probes; and finally, in periodic operational data collect obtained during the off-shore oil platform systems operation. The ICMP will direct and manage the actions to be taken in case of aggravation of a corrosive process, quickly identifying to the corrosive mechanisms and its localization in the various systems of the platforms. The optimized use of the corrosion inhibitor and other chemical products are one of the main advantages of the ICMP.

  11. Corrosion Protection of Electrically Conductive Surfaces

    Directory of Open Access Journals (Sweden)

    Jian Song

    2012-11-01

    Full Text Available The basic function of the electrically conductive surface of electrical contacts is electrical conduction. The electrical conductivity of contact materials can be largely reduced by corrosion and in order to avoid corrosion, protective coatings must be used. Another phenomenon that leads to increasing contact resistance is fretting corrosion. Fretting corrosion is the degradation mechanism of surface material, which causes increasing contact resistance. Fretting corrosion occurs when there is a relative movement between electrical contacts with surfaces of ignoble metal. Avoiding fretting corrosion is therefore extremely challenging in electronic devices with pluggable electrical connections. Gold is one of the most commonly used noble plating materials for high performance electrical contacts because of its high corrosion resistance and its good and stable electrical behavior. The authors have investigated different ways to minimize the consumption of gold for electrical contacts and to improve the performance of gold plating. Other plating materials often used for corrosion protection of electrically conductive surfaces are tin, nickel, silver and palladium. This paper will deal with properties and new research results of different plating materials in addition to other means used for corrosion protection of electrically conductive surfaces and the testing of corrosion resistance of electrically conductive surfaces.

  12. 49 CFR 192.477 - Internal corrosion control: Monitoring.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Internal corrosion control: Monitoring. 192.477... Control § 192.477 Internal corrosion control: Monitoring. If corrosive gas is being transported, coupons... internal corrosion. Each coupon or other means of monitoring internal corrosion must be checked two...

  13. 49 CFR 192.491 - Corrosion control records.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Corrosion control records. 192.491 Section 192.491... BY PIPELINE: MINIMUM FEDERAL SAFETY STANDARDS Requirements for Corrosion Control § 192.491 Corrosion... detail to demonstrate the adequacy of corrosion control measures or that a corrosive condition does...

  14. Corrosion Behaviour of Titanium Anodized Film in Different Corrosive Environments

    Directory of Open Access Journals (Sweden)

    Mr. Sunil D. Kahar

    2014-07-01

    Full Text Available Anodizing is an electrochemical process in which thickness of the natural oxide layer is increased and converted it into a decorative, durable, corrosion-resistant film. Titanium is used as a biocompatible material in human implants due to its excellent corrosion and wears resistance. Stable, continuous, highly adherent, and protective oxide films can be developed on titanium using various acid or alkaline baths. Anodizing of titanium generates a spectrum of different color without use of dyes. This spectrum of color dependent on the thickness of the oxide, voltage ranges, interference of light reflecting off the oxide surface and reflecting off the underlying metal surface. The anodized film of Titanium is mainly consists of TiO2 or mixtures of TiO2 & Ti2O3 etc. In the present work, Pure Titanium plate has been anodized using bath of Chromic Acid at different voltage range. The anodized film is characterized by visual observation, SEM & EDAX analysis & A.C Impedance Spectroscopy, while the corrosion studies were performed using Potentiodynamic studies were performed in 3.5% NaCl & 0.1N H2SO4. The Results show that the anodized film of Titanium show different spectrum of colors from Brown-Violet-Tea or Peacock. SEM & EDAX analyses show that the anodized film of Titanium is mainly made up of TiO2 and Ti2O3. Potentiodynamic study implies that the film developed on Titanium using the bath of Chromic Acid exhibits good corrosion resistance. The A.C. Impedance study shows that the film is more compact, adherent and more uniform in chromic acid bath.

  15. A non-destructive test method to monitor corrosion products and corrosion-induced cracking in reinforced cement based materials

    DEFF Research Database (Denmark)

    Michel, Alexander; Pease, Bradley Justin; Peterova, Adela;

    2011-01-01

    ) was conducted to describe the impact of water-to-cement ratio and corrosion current density (i.e., corrosion rate) on the reinforcement corrosion process. Focus was placed, in particular on the determination of the corrosion accommodating region (CAR) and time to corrosion-induced cracking. Experimental results...

  16. Acción antimicrobiana in vitro de dentífricos conteniendo fitoterápicos Antimicrobial action in vitro of dentifricies with phytoterapeutics agents

    Directory of Open Access Journals (Sweden)

    Liza Barreto V

    2005-08-01

    Full Text Available Este estudio analizó el potencial antimicrobiano in vitro de 7 dentífricos conteniendo fitoterápicos sobre bacterias orales recuperadas de la saliva y cepas patrón de S. mutans ATCC25175, S. sanguis ATCC 10556 y L. casei ATCC 4646. Fueron obtenidas soluciones concentradas de los dentífricos evaluados y de controles mezclándose 3 gramos de cada uno con 10 mL de agua deionozada estéril, seguido de centrifugación; los sobrenadantes resultantes fueron diluidos en proporciones de 1:2 hasta 1:32. Fue realizado un test de difusión en ágar, colocando cepas patrón y la saliva total estimulada de 10 pacientes saludables. Discos empapados con las suspensiones de los dentífricos fueron dispuestos en las placas, las cuales fueron incubadas en anaerobiosis por 48 horas, siendo los aros de inhibición medidos en milímetros. Los resultados obtenidos fueron analizados mediante ANOVA y llevando en consideración el control positivo se constató que, solamente las soluciones puras de los dentífricos presentaron capacidad antimicrobiana contra cepas patrón, equivalente a la del dentífrico con triclosan, excepto el Gessy Cristal®. Además, los dentífricos diluidos a 1:2 presentaron acción antimicrobiana contra las bacterias orales recuperadas de la saliva, excepto el Parodontax®.The aim of this study was to evaluate and compare in vitro antimicrobial potential of 7 dentifrices containing phytotherapics agents oral bacteria obtained from saliva and standard strains of S. mutans ATCC 25175, S. sanguis ATCC 10556, and L. casei ATCC 4646. For this purpose, concentrated test and control solutions were obtained by mixing 3 grams of each in 10 ml of sterile deionized water which was submitted to centrifugation, the sublimate obtained was further dissolved in a ratio of 1:2 to 1:32. A diffusion test in agar was carried out by sowing the standard strain and stimulated total saliva. Disks soaked in a dentifrices solution and then placed on culture disks

  17. Avaliação de titânio puro metálico e zircônia estabilizada com ítria para aplicação em implantes dentários

    OpenAIRE

    Sidival Dias Junior

    2011-01-01

    Implantes dentários normalmente são fabricados com titânio, devido as suas excelentes propriedades mecânicas e biocompatibilidade. Apesar de permitirem uma excelente integração funcional e histológica, a necessidade de satisfazer aos requisitos estéticos nem sempre é possível. Com o objetivo de substituir a infraestrutura metálica de próteses dentárias e implantes, cerâmicas estruturais foram melhoradas e tornaram-se cada vez mais populares na odontologia. Entre as cerâmicas dentárias, a zirc...

  18. Continuum and line modelling of discs around young stars. II. Line diagnostics for GASPS from the DENT grid

    Science.gov (United States)

    Kamp, I.; Woitke, P.; Pinte, C.; Tilling, I.; Thi, W.-F.; Menard, F.; Duchene, G.; Augereau, J.-C.

    2011-08-01

    Aims: We want to understand the chemistry and physics of discs on the basis of a large unbiased and statistically relevant grid of disc models. One of the main goals is to explore the diagnostic power of various gas emission lines and line ratios for deriving main disc parameters such as the gas mass. Methods: We explored the results of the DENT grid (Disk Evolution with Neat Theory) that consists of 300 000 disc models with 11 free parameters. Through a statistical analysis, we searched for correlations and trends in an effort to find tools for disc diagnostic. Results: All calculated quantities like species masses, temperatures, continuum, and line fluxes differ by several orders of magnitude across the entire parameter space. The broad distribution of these quantities as a function of input parameters shows the limitation of using a prototype T Tauri or Herbig Ae/Be disc model. The statistical analysis of the DENT grid shows that CO gas is rarely the dominant carbon reservoir in discs. Models with large inner radii (10 times the dust condensation radius) and/or shallow surface density gradients lack massive gas-phase water reservoirs. Also, 60% of the discs have gas temperatures averaged over the oxygen mass in the range between 15 and 70 K; the average gas temperatures for CO and O differ by less than a factor two. Our study of the observational diagnostics shows that the [C ii] 158 μm fine structure line flux is very sensitive to the stellar UV flux and presence of a UV excess, and that it traces the outer disc radius (Rout). In the submm, the CO low J rotational lines also trace Rout. Low [O i] 63/145 line ratios (

  19. Identification et prise en charge des femmes ayant des antécédents familiaux de cancer du sein

    Science.gov (United States)

    Heisey, Ruth; Carroll, June C.

    2016-01-01

    Résumé Objectif Résumer les meilleures données portant sur les stratégies d’identification et de prise en charge des femmes qui présentent des antécédents familiaux de cancer du sein. Sources d’information Une recherche a été effectuée sur PubMed à l’aide des mots-clés anglais suivants : breast cancer, guidelines, risk, family history, management et magnetic resonance imaging screening, entre 2000 et 2016. La plupart des données sont de niveau II. Message principal Une bonne anamnèse familiale est essentielle lors de l’évaluation du risque de cancer du sein afin d’identifier les femmes qui sont candidates à une recommandation en counseling génétique pour un éventuel test génétique. On peut sauver des vies en offrant aux femmes porteuses d’une mutation au gène BRCA des interventions chirurgicales de réduction des risques (mastectomie bilatérale prophylactique, salpingo-ovariectomie bilatérale). Il faut encourager toutes les femmes qui présentent des antécédents familiaux de cancer du sein à demeurer actives et à limiter leur consommation d’alcool à moins de 1 verre par jour; certaines femmes sont admissibles à la chimioprévention. Il faut offrir aux femmes dont le risque à vie de cancer du sein est de 20 à 25 % ou plus un dépistage poussé par imagerie par résonance magnétique en plus d’une mammographie. Conclusion Une vie saine et la chimioprévention (chez les candidates) pourraient réduire l’incidence du cancer du sein; le dépistage poussé pourrait entraîner une détection plus précoce. Le fait d’aiguiller des femmes porteuses d’une mutation au BRCA vers la chirurgie de réduction des risques sauve des vies. PMID:27737991

  20. Corrosion-Activated Micro-Containers for Environmentally Friendly Corrosion Protective Coatings

    Science.gov (United States)

    Li, Wenyan; Buhrow, J. W.; Zhang, X.; Johnsey, M. N.; Pearman, B. P.; Jolley, S. T.; Calle, L. M.

    2016-01-01

    This work concerns the development of environmentally friendly encapsulation technology, specifically designed to incorporate corrosion indicators, inhibitors, and self-healing agents into a coating, in such a way that the delivery of the indicators and inhibitors is triggered by the corrosion process, and the delivery of self-healing agents is triggered by mechanical damage to the coating. Encapsulation of the active corrosion control ingredients allows the incorporation of desired autonomous corrosion control functions such as: early corrosion detection, hidden corrosion detection, corrosion inhibition, and self-healing of mechanical damage into a coating. The technology offers the versatility needed to include one or several corrosion control functions into the same coating.The development of the encapsulation technology has progressed from the initial proof-of-concept work, in which a corrosion indicator was encapsulated into an oil-core (hydrophobic) microcapsule and shown to be delivered autonomously, under simulated corrosion conditions, to a sophisticated portfolio of micro carriers (organic, inorganic, and hybrid) that can be used to deliver a wide range of active corrosion ingredients at a rate that can be adjusted to offer immediate as well as long-term corrosion control. The micro carriers have been incorporated into different coating formulas to test and optimize the autonomous corrosion detection, inhibition, and self-healing functions of the coatings. This paper provides an overview of progress made to date and highlights recent technical developments, such as improved corrosion detection sensitivity, inhibitor test results in various types of coatings, and highly effective self-healing coatings based on green chemistry. The NASA Kennedy Space Centers Corrosion Technology Lab at the Kennedy Space Center in Florida, U.S.A. has been developing multifunctional smart coatings based on the microencapsulation of environmentally friendly corrosion

  1. Electrochemical corrosion testing of metal waste forms

    Energy Technology Data Exchange (ETDEWEB)

    Abraham, D. P.; Peterson, J. J.; Katyal, H. K.; Keiser, D. D.; Hilton, B. A.

    1999-12-14

    Electrochemical corrosion tests have been conducted on simulated stainless steel-zirconium (SS-Zr) metal waste form (MWF) samples. The uniform aqueous corrosion behavior of the samples in various test solutions was measured by the polarization resistance technique. The data show that the MWF corrosion rates are very low in groundwaters representative of the proposed Yucca Mountain repository. Galvanic corrosion measurements were also conducted on MWF samples that were coupled to an alloy that has been proposed for the inner lining of the high-level nuclear waste container. The experiments show that the steady-state galvanic corrosion currents are small. Galvanic corrosion will, hence, not be an important mechanism of radionuclide release from the MWF alloys.

  2. CORROSION MONITORING OF PLUTONIUM OXIDE AND SNF

    Energy Technology Data Exchange (ETDEWEB)

    Douglas, D.G.; Haas, C.M.; Smith, C.M.; Ohl, P.C.

    2003-02-27

    While developing a method to measure pressure in totally sealed stainless steel containers holding spent nuclear fuel at the U.S. DOE Hanford Site, Vista Engineering Technologies, LLC (Vista Engineering) personnel adapted the central concept to corrosion monitoring techniques for the same containers. The ability to monitor corrosion within vessels containing spent nuclear fuel, plutonium and other hazardous materials is imperative for safe storage. Vista Engineering personnel have devised a way to monitor corrosion in a totally sealed stainless steel container using a Magnetically Coupled Corrosion Gauge (MCCG) Patent Pending. The MCCG can be used to detect corrosion as well as measure corrosion rate and does not require any penetration of the containment vessel, which minimizes pressure boundary surface area and sensitive weld materials in the vessels.

  3. Microbiologically Influenced Corrosion: an Update

    Science.gov (United States)

    2014-01-01

    the material that failed was carbon steel and the electrolyte were saline waters, but the microorgan- isms, the environments and the corrosion...different salinities . Martin et al.42 demonstrated that Ecorr ennoblement was site specific, varying 100 mV versus SCE between locations, with higher...microbial consortium of the fungus Aspergillus niger and bacteria influenced the corrosion–inhibiting effectiveness of Crz6 leached from chromate (CrO{24

  4. Aluminum corrosion product release kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, Matt, E-mail: Matthew.Edwards@cnl.ca; Semmler, Jaleh; Guzonas, Dave; Chen, Hui Qun; Toor, Arshad; Hoendermis, Seanna

    2015-07-15

    Highlights: • Release of Al corrosion product was measured in simulated post-LOCA sump solutions. • Increased boron was found to enhance Al release kinetics at similar pH. • Models of Al release as functions of time, temperature, and pH were developed. - Abstract: The kinetics of aluminum corrosion product release was examined in solutions representative of post-LOCA sump water for both pressurized water and pressurized heavy-water reactors. Coupons of AA 6061 T6 were exposed to solutions in the pH 7–11 range at 40, 60, 90 and 130 °C. Solution samples were analyzed by inductively coupled plasma atomic emission spectroscopy, and coupon samples were analyzed by secondary ion mass spectrometry. The results show a distinct “boron effect” on the release kinetics, expected to be caused by an increase in the solubility of the aluminum corrosion products. New models were developed to describe both sets of data as functions of temperature, time, and pH (where applicable)

  5. Corrosion behavior in heat pipe

    Directory of Open Access Journals (Sweden)

    Anurak Rodbumrung

    2016-01-01

    Full Text Available The aim of this study was to perform life testing and determine the effect of working fluid on the corrosion of a heat pipe with a sintered wick. The heat pipe was made from a copper tube. The inner heat pipe was filled with 99.97% pure copper powder as a dendritic for the sintering process. The heat pipe had an outer diameter of 6 mm with a length of 200 mm, and distilled water and ethanol were the working fluids. The operating temperature at the evaporator was 125°C. The analysis consisted of using a scanning electron microscope, energy dispersive X-ray spectrometry and atomic absorption spectroscopy. The results of the scanning electron microscope and energy dispersive X-ray spectrometry analysis showed that the corrosion of the heat pipe was uniform. The result of the atomic absorption spectroscopy indicated that the concentration of the copper in the ethanol as the working fluid was greater than in the distilled water as the working fluid, and the highest concentration of copper particles in the ethanol was 22.7499 ppm or 0.0409 mg after testing for 3000 h. The concentration of copper was higher when the length of the life test increased due to corrosion of the heat pipe.

  6. Corrosion Preventive Compounds Lifetime Testing

    Science.gov (United States)

    Hale, Stephanie M.; Kammerer, Catherine C.; Copp, Tracy L.

    2007-01-01

    Lifetime Testing of Corrosion Preventive Compounds (CPCs) was performed to quantify performance in the various environments to which the Space Shuttle Orbiter is exposed during a flight cycle. Three CPCs are approved for use on the Orbiter: RD Calcium Grease, Dinitrol AV-30, and Braycote 601 EF. These CPCs have been rigorously tested to prove that they mitigate corrosion in typical environments, but little information is available on how they perform in the unique combination of the coastal environment at the launch pad, the vacuum of low-earth orbit, and the extreme heat of reentry. Currently, there is no lifetime or reapplication schedule established for these compounds that is based on this combination of environmental conditions. Aluminum 2024 coupons were coated with the three CPCs and exposed to conditions that simulate the environments to which the Orbiter is exposed. Uncoated Aluminum 2024 coupons were exposed to the environmental conditions as a control. Visual inspection and Electro- Impedance Spectroscopy (EIS) were performed on the samples in order to determine the effectiveness of the CPCs. The samples were processed through five mission life cycles or until the visual inspection revealed the initiation of corrosion and EIS indicated severe degradation of the coating.

  7. Corrosion performance of iron aluminides

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.

    1993-03-01

    Iron aluminides are being developed for use as structural materials and/or cladding alloys in fossil energy systems. Extensive development has been in progress on Fe{sub 3}Al-based alloys to improve the engineering ductility of these alloys. This paper describes results from the ongoing program to evaluate the corrosion performance of these alloys. The experimental program at Argonne National Laboratory involvesthermogravimetric analyses of alloys exposed to environments that simulate coal gasification and fluidized-bed combustion. Experiments were conducted at 650--1000{degrees}C in simulated oxygen/sulfur gas mixtures. In addition, oxidation/sulfidation behavior of several alumina-forming Fe-Al and Fe-Cr-Ni-Al alloys was determined for comparison with the corrosion rates obtained on iron aluminides. Other aspects of the program are corrosion evaluation of the aluminides in the presence of HC1-containing gases and in the presence of slag from a slogging gasifier. Results are used to establish threshold Al levels in the alloys for development of protective alumina scales. Thermal cycling tests are used to examine the spalling resistance of the scales.

  8. Corrosion performance of iron aluminides

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.

    1993-03-01

    Iron aluminides are being developed for use as structural materials and/or cladding alloys in fossil energy systems. Extensive development has been in progress on Fe[sub 3]Al-based alloys to improve the engineering ductility of these alloys. This paper describes results from the ongoing program to evaluate the corrosion performance of these alloys. The experimental program at Argonne National Laboratory involvesthermogravimetric analyses of alloys exposed to environments that simulate coal gasification and fluidized-bed combustion. Experiments were conducted at 650--1000[degrees]C in simulated oxygen/sulfur gas mixtures. In addition, oxidation/sulfidation behavior of several alumina-forming Fe-Al and Fe-Cr-Ni-Al alloys was determined for comparison with the corrosion rates obtained on iron aluminides. Other aspects of the program are corrosion evaluation of the aluminides in the presence of HC1-containing gases and in the presence of slag from a slogging gasifier. Results are used to establish threshold Al levels in the alloys for development of protective alumina scales. Thermal cycling tests are used to examine the spalling resistance of the scales.

  9. Optimising corrosion monitoring in district heating systems

    DEFF Research Database (Denmark)

    Hilbert, Lisbeth Rischel; Thorarinsdottir, R.I.; Andersen, A.

    2002-01-01

    A three-year project - financially supported by the Nordic Industrial Fund - on monitoring of corrosion in district heating systems has been initiated with participation of researchers and industrial partners in Denmark, Finland, Iceland, Norway and Sweden. The primary objective of the project...... is to improve the quality control in district heating systems by corrosion monitoring. In Danish systems electrochemical impedance spectroscopy (EIS), linear polarisation resistance (LPR), high-sensitive electrical resistance (ER) technology, crevice corrosion probes, as well as weight loss coupons...

  10. Recognition and Analysis of Corrosion Failure Mechanisms

    OpenAIRE

    Steven Suess

    2006-01-01

    Corrosion has a vast impact on the global and domestic economy, and currently incurs losses of nearly $300 billion annually to the U.S. economy alone. Because of the huge impact of corrosion, it is imperative to have a systematic approach to recognizing and mitigating corrosion problems as soon as possible after they become apparent. A proper failure analysis includes collection of pertinent background data and service history, followed by visual inspection, photographic documentation, materi...

  11. Corrosive acid injury of the stomach.

    Science.gov (United States)

    Wijeratne, T; Ratnatunga, C; Dharrmapala, A; Samarasinghe, T

    2015-03-01

    Ingestion of corrosives with accidental or suicidal intent is a common problem in Sri Lanka. Management options and outcomes of corrosive injuries on stomach are not well documented in our setting. The clinical presentation, complications and management outcomes of nine patients with corrosive injury to stomach are presented. Gastric outlet obstruction seen in majority, was managed with bypass procedure (n=5) or resection (n=4). The outcomes of management were successful with both methods.

  12. The oxidation and corrosion of ODS alloys

    Science.gov (United States)

    Lowell, Carl E.; Barrett, Charles A.

    1990-01-01

    The oxidation and hot corrosion of high temperature oxide dispersion strengthened (ODS) alloys are reviewed. The environmental resistance of such alloys are classified by oxide growth rate, oxide volatility, oxide spalling, and hot corrosion limitations. Also discussed are environmentally resistant coatings for ODS materials. It is concluded that ODS NiCrAl and FeCrAl alloys are highly oxidation and corrosion resistant and can probably be used uncoated.

  13. Oxidation And Hot Corrosion Of ODS Alloy

    Science.gov (United States)

    Lowell, Carl E.; Barrett, Charles A.

    1993-01-01

    Report reviews oxidation and hot corrosion of oxide-dispersion-strengthened (ODS) alloys, intended for use at high temperatures. Classifies environmental resistances of such alloys by rates of growth of oxides, volatilities of oxides, spalling of oxides, and limitations imposed by hot corrosion. Also discusses environmentally resistant coatings for ODS materials. Concludes ODS NICrAl and FeCrAl alloys highly resistant to oxidation and corrosion and can be used uncoated.

  14. Corrosion of oil-fired domestic boilers

    Energy Technology Data Exchange (ETDEWEB)

    Koebel, M.; Elsener, M.

    1989-05-01

    Depending on the surface temperature of the flue gas side the corrosion of oil fired domestic boilers proceeds either mainly by acid corrosion or by oxygen corrosion: (1) At surface temperatures of 60/sup 0/C and higher the corrosion mechanism of acid corrosion prevails and the corrosion rates amount to 0.1-0.3 mm/year (values referred to continuous burner operation). The corrosion products consist of soluble iron(II)- and iron(III)sulfates. Higher corrosion rates can be attributed to an appreciable catalytic formation of sulfur trioxide on the corrosion products formed on the convective heating surfaces. (2) At surface temperatures of 40/sup 0/C the mechanism of oxygen corrosion already dominates and the corrosion rates are about ten times higher (1.5-3 mm/year, referred to continuous burner operation). The high portion of iron oxide hydrates, especially goethit (/alpha/-FeOOH), makes the corrosion products difficult to remove. (3) Distinctly reduced service lives are also expected for the so called reduced temperature boilers ('Niedertemperaturkessel') and low temperature boilers ('Tieftemperaturkessel'): According to the manufacturers these boilers may be operated at boiler water temperatures well below 60/sup 0/C, as they are equipped with constructive measures to enhance the surface temperature on the flue gas side. However, these measures are only fully effective under stationary conditions. Some of the results were obtained from weight loss measurements on test specimen made from St 35.8 and gray cast iron, that were exposed to the flue gases of an fired experimental boiler. Other important results come from field measurements of the sulfuric acid content of about 30 boilers that are in practical use. (orig.).

  15. Natural analogues of nuclear waste glass corrosion.

    Energy Technology Data Exchange (ETDEWEB)

    Abrajano, T.A. Jr.; Ebert, W.L.; Luo, J.S.

    1999-01-06

    This report reviews and summarizes studies performed to characterize the products and processes involved in the corrosion of natural glasses. Studies are also reviewed and evaluated on how well the corrosion of natural glasses in natural environments serves as an analogue for the corrosion of high-level radioactive waste glasses in an engineered geologic disposal system. A wide range of natural and experimental corrosion studies has been performed on three major groups of natural glasses: tektite, obsidian, and basalt. Studies of the corrosion of natural glass attempt to characterize both the nature of alteration products and the reaction kinetics. Information available on natural glass was then compared to corresponding information on the corrosion of nuclear waste glasses, specifically to resolve two key questions: (1) whether one or more natural glasses behave similarly to nuclear waste glasses in laboratory tests, and (2) how these similarities can be used to support projections of the long-term corrosion of nuclear waste glasses. The corrosion behavior of basaltic glasses was most similar to that of nuclear waste glasses, but the corrosion of tektite and obsidian glasses involves certain processes that also occur during the corrosion of nuclear waste glasses. The reactions and processes that control basalt glass dissolution are similar to those that are important in nuclear waste glass dissolution. The key reaction of the overall corrosion mechanism is network hydrolysis, which eventually breaks down the glass network structure that remains after the initial ion-exchange and diffusion processes. This review also highlights some unresolved issues related to the application of an analogue approach to predicting long-term behavior of nuclear waste glass corrosion, such as discrepancies between experimental and field-based estimates of kinetic parameters for basaltic glasses.

  16. Recognition and Analysis of Corrosion Failure Mechanisms

    OpenAIRE

    Steven Suess

    2006-01-01

    Corrosion has a vast impact on the global and domestic economy, and currently incurs losses of nearly $300 billion annually to the U.S. economy alone. Because of the huge impact of corrosion, it is imperative to have a systematic approach to recognizing and mitigating corrosion problems as soon as possible after they become apparent. A proper failure analysis includes collection of pertinent background data and service history, followed by visual inspection, photographic documentation, materi...

  17. Corrosion Properties of Laser Welded Stainless Steel

    DEFF Research Database (Denmark)

    Weldingh, Jakob; Olsen, Flemmming Ove

    1997-01-01

    In this paper the corrosion properties of laser welded AISI 316L stainless steel are examined. A number of different welds has been performed to test the influence of the weld parameters of the resulting corrosion properties. It has been chosen to use the potential independent critical pitting...... temperature (CPT) test as corrosion test. The following welding parameters are varied: Welding speed, lsser power, focus point position and laser operation mode (CW or pulsed)....

  18. Corrosion problems and solutions in oil refining and petrochemical industry

    CERN Document Server

    Groysman, Alec

    2017-01-01

    This book addresses corrosion problems and their solutions at facilities in the oil refining and petrochemical industry, including cooling water and boiler feed water units. Further, it describes and analyzes corrosion control actions, corrosion monitoring, and corrosion management. Corrosion problems are a perennial issue in the oil refining and petrochemical industry, as they lead to a deterioration of the functional properties of metallic equipment and harm the environment – both of which need to be protected for the sake of current and future generations. Accordingly, this book examines and analyzes typical and atypical corrosion failure cases and their prevention at refineries and petrochemical facilities, including problems with: pipelines, tanks, furnaces, distillation columns, absorbers, heat exchangers, and pumps. In addition, it describes naphthenic acid corrosion, stress corrosion cracking, hydrogen damages, sulfidic corrosion, microbiologically induced corrosion, erosion-corrosion, and corrosion...

  19. Accelerated corrosion testing results for specimens containing uncoated reinforcing steel and corrosion inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Kondratova, I. L.; Montes, P.; Bremner, T. W. [New Brunswick Univ., Dept, of Civil Engineering, Fredericton, NB (Canada)

    2000-07-01

    Concrete mixtures (water-cement ratios of 0.25, 0.40. or 0.60) containing uncoated reinforcing bars with a simulated crack, formed transverse to the axis of the bar, and with three commercial corrosion inhibitors added for corrosion protection (organic corrosion inhibitor,calcium nitrate-based corrosion inhibitor, and migratory corrosion inhibitor), were tested for corrosion damage. The objective was to evaluate the effectiveness of the different corrosion inhibitors in uncracked and cracked concrete slabs in a simulated marine environment. The specimens were placed in an accelerated exposure cabinet with four cycles of wetting and drying per day in simulated seawater, and corrosion rates measured using the linear polarization technique. Water-soluble chloride content in the rebars was analyzed at the end of the exposure period. The three corrosion inhibitors were found to show a wide variation in performance. There was a direct correlation between their effectiveness and addition rate. All three appeared to be more effective in reducing corrosion rate in a higher water-to-cement ratio concrete. Consistent performance was provided only by calcium nitrate at an addition rate of 25 litre/cu m of concrete, with water-to-cement ratios of 0.60 and 0.40. Pitting corrosion was observed in all pre-cracked high performance concrete specimens; the depth of the pit tended to be deeper when a corrosion inhibitor was used. 6 refs., 6 tabs., 6 figs.

  20. New corrosion issues in gas sweetening plants

    Energy Technology Data Exchange (ETDEWEB)

    Asperger, R.G. (CLI International and Asperger Technologies, Houston, TX (United States))

    Gas treating plants are experiencing corrosion problems which impact on efficiency and safety. While general corrosion is not particularly hazardous in the gas processing industry, local corrosion is very dangerous since it has several different mechanisms, all of which have dangerously high rates, and it occurs at locations which are hard to find and hard to predict. A newly discovered, velocity-dependent type of corrosion is reported. It is related to yet-undefined species which cause excessively high corrosion in areas of turbulence. This accelerated corrosion is not due to erosion or cavitation, but to a diffusion-limited reaction accelerated by turbulence. A full-flow test loop was built to evaluate the corrosiveness of gas plant solutions at their normal temperature and flow rates. Test runs were conducted with Co[sub 2]-loaded amine solutions for periods of 12 days. Carbon steel specimens mounted in the test loop were examined and corrosion rates calculated. Chromium alloys were shown to be attacked by corrodents in the low-velocity part of the loop and very aggressively attacked in the high-velocity part. The tests demonstrate the need for rigorous monitoring of corrosion in areas of higher velocity such as piping elbows and other points of turbulence. 5 refs., 2 figs., 3 tabs.

  1. Fouling corrosion in aluminum heat exchangers

    Directory of Open Access Journals (Sweden)

    Su Jingxin

    2015-06-01

    Full Text Available Fouling deposits on aluminum heat exchanger reduce the heat transfer efficiency and cause corrosion to the apparatus. This study focuses on the corrosive behavior of aluminum coupons covered with a layer of artificial fouling in a humid atmosphere by their weight loss, Tafel plots, electrochemical impedance spectroscopy (EIS, and scanning electron microscope (SEM observations. The results reveal that chloride is one of the major elements found in the fouling which damages the passive film and initiates corrosion. The galvanic corrosion between the metal and the adjacent carbon particles accelerates the corrosive process. Furthermore, the black carbon favors the moisture uptake, and gives the dissolved oxygen greater chance to migrate through the fouling layer and form a continuous diffusive path. The corrosion rate decreasing over time is conformed to electrochemistry measurements and can be verified by Faraday’s law. The EIS results indicate that the mechanism of corrosion can be interpreted by the pitting corrosion evolution mechanism, and that pitting was observed on the coupons by SEM after corrosive exposure.

  2. Classification of corrosion risk zones using GIS

    Science.gov (United States)

    Georgiou, Nikolas; Anastasiou, Constantina; Tantele, Elia A.; Votsis, Renos A.; Danezis, Chris

    2016-08-01

    Corrosion of steel reinforcement is the major deterioration factor of the RC infrastructures. Several factors are contributing towards increasing the corrosion risk like the exposure and environmental conditions which are a function of the geographical location of the infrastructure. Information for these conditions and their affected areas can be proved valuable at design stage and/or during maintenance planning. This study aims to relate corrosion risk of RC infrastructures with their geographical location. The corrosion risk is quantified through data from NDT methods and subsequently correlated with its location. Therefore high risk areas with structures prone to corrosion deterioration are identified. The latter is implemented via GIS tools in order to create maps that describe how corrosion risk is related to the location of each structure. Two GIS methods are suggested, the grid system and the use of classified areas. Corrosion data has been collected from labs about various constructions in Cyprus and used in conjunction with GIS tools to provide useful information on corrosion identification. The outcome is a digitized map of the Limassol area which indicates the risks levels associated with corrosion of the steel reinforcement.

  3. NOVEL CORROSION SENSOR FOR VISION 21 SYSTEMS

    Energy Technology Data Exchange (ETDEWEB)

    Heng Ban

    2004-12-01

    Advanced sensor technology is identified as a key component for advanced power systems for future energy plants that would have virtually no environmental impact. This project intends to develop a novel high temperature corrosion sensor and subsequent measurement system for advanced power systems. Fireside corrosion is the metal loss caused by chemical reactions on surfaces exposed to the combustion environment. Such corrosion is the leading mechanism for boiler tube failures and has emerged to be a significant concern for current and future energy plants due to the introduction of technologies targeting emissions reduction, efficiency improvement, or fuel/oxidant flexibility. Corrosion damage can lead to catastrophic equipment failure, explosions, and forced outages. Proper management of corrosion requires real-time indication of corrosion rate. However, short-term, on-line corrosion monitoring systems for fireside corrosion remain a technical challenge to date due to the extremely harsh combustion environment. The overall objective of this proposed project is to develop a technology for on-line corrosion monitoring based on a new concept. This report describes the initial results from the first-year effort of the three-year study that include laboratory development and experiment, and pilot combustor testing.

  4. Recent Corrosion Research Trends in Weld Joints

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hwan Tae; Kil, Sang Cheol [Korea Institute of Science and Technology Information, Seoul (Korea, Republic of); Hwang, Woon Suk [Inha University, Incheon (Korea, Republic of)

    2007-04-15

    The increasing interest in the corrosion properties of weld joints in the corrosive environment is placing stringent demands on the manufacturing techniques and performance requirements, and the manufacture employs the high quality and efficiency welding process to produce welds. Welding plays an important role in the fabrication of chemical plants, nuclear power plant, ship construction, and this has led to an increasing attention to the corrosion resistant weld joints. This paper covers recent technical trends of welding technologies for corrosion resistance properties including the COMPENDEX DB analysis of welding materials, welding process, and welding fabrications

  5. Corrosion Fatigue in District Heating Water Tanks

    DEFF Research Database (Denmark)

    Maahn, Ernst Emanuel

    1996-01-01

    Three candidate materials for construction of buffer tanks for district heating water have been tested for corrosion fatigue properties in a district heating water environment. The investigation included Slow Strain Rate Testing of plain tensile specimens, crack initiation testing by corrosion...... fatigue of plain tensile specimens and crack growth rate determination for Compact Tensile Specimens under corrosion fatigue conditions. The three materials are equal with respect to stress corrosion sensibility and crack initiation. Crack growth rate is increased with a factor of 4-6 relative to an inert...

  6. Pesquisa de microrganismos nos aerossóis libertados durante o procedimento de destartarização dentária em canídeos

    OpenAIRE

    Dias, Isabel Rosa Sezinando

    2014-01-01

    Dissertação de Mestrado Integrado em Medicina Veterinária A doença periodontal é a doença mais comum da cavidade oral em cães, tendo como principal etiologia a formação de placa bacteriana e de cálculo dentário. No tratamento da doença periodontal a remoção de placa bacteriana e de cálculo é feita recorrendo ao procedimento de destartarização dentária. Durante este procedimento ocorre a formação de aerossóis e gotículas, devido ao uso e aparelhos mecânicos ultrassónicos. Um dos riscos asso...

  7. Dental age in patients with Down syndrome Idade dentária em pacientes com síndrome de Down

    Directory of Open Access Journals (Sweden)

    Mari Eli Leonelli de Moraes

    2007-09-01

    Full Text Available The aim of this research was to evaluate dental age in 102 patients with Down Syndrome, using panoramic radiographs. A software program developed by the Discipline of Radiology, School of Dentistry of São José dos Campos, São Paulo State University (UNESP, was used. A table of mineralization chronology of permanent teeth among Brazilians conceived by Nicodemo, Moraes and Medici Filho was used within the software. Statistical analysis of the results showed that 70.91% of the males and 61.21% of the females presented advanced dental age. Only 32.09% of the males and 38.79% of the females presented delayed dental age. Regarding the differences between the dental and chronological ages, two thirds of the males and females presented dental age with differences of up to 12 months, which means that they can be considered to be within normal standards, whereas only 18.87% of the males and 10.21% of the females presented dental age outside normal standards, with differences of over 24 months. In conclusion, the majority of the patients with Down Syndrome were considered to be within the normal standards of mineralization chronology.O objetivo desta pesquisa foi avaliar a idade dentária em 102 indivíduos com síndrome de Down, por meio de radiografias panorâmicas. Foi usado um "software" desenvolvido pela disciplina de Radiologia da Faculdade de Odontologia de São José dos Campos (UNESP. Neste "software", foi utilizada a tabela de cronologia de mineralização dos dentes permanentes entre brasileiros, de Nicodemo, Moraes e Medici Filho. A análise estatística dos resultados mostrou que 70,91% dos indivíduos do sexo masculino e 61,21% do sexo feminino apresentaram idade dentária adiantada. Apenas 32,09% dos indivíduos do sexo masculino e 38,79% dos indivíduos do sexo feminino apresentaram idade dentária atrasada. Com relação às diferenças entre idade dentária e idade cronológica, dois terços dos indivíduos dos sexos masculino e

  8. Validação e confiabilidade de um novo instrumento para detecção de cárie dentária

    OpenAIRE

    Souza, Ana Luiza de

    2014-01-01

    Introdução: O CAST (Caries Assessment Spectrum and Treatment) é um instrumento hierárquico de detecção de cárie dentária para uso epidemiológico que permite o registro de dentes hígidos, selantes, restaurações, lesões de cárie em esmalte e dentina, progressão na polpa e nos tecidos adjacentes. Objetivos: Validar o instrumento CAST para face e conteúdo (Estudo 1), construto (Estudo 2) e determinar sua confiabilidade clínica (Estudo 3). Métodos e Resultados: Estudo 1: 17 afirmações relacionadas...

  9. Fluorose dentária em crianças de Princesa Isabel, Paraíba Dental fluorosis in children from Princesa Isabel, Paraíba

    Directory of Open Access Journals (Sweden)

    Franklin Delano Soares FORTE

    2001-06-01

    Full Text Available Diversas localidades da Paraíba possuem níveis moderados ou elevados de fluoreto in natura nas águas de abastecimento. Nas áreas onde os níveis de fluoretos são considerados "ótimos" para a região (0,6 ppm, já constatou-se uma moderada prevalência de fluorose dentária (30-40%. O presente trabalho teve por objetivo observar a prevalência de fluorose dentária na cidade de Princesa Isabel, com níveis "subótimos" de fluoretos (0,4 ppm. Foram selecionados aleatoriamente 142 escolares de 10 a 15 anos para o levantamento de fluorose dentária pelo índice TF (de Thylstrup e Fejerskov. Os exames foram realizados por três examinadores previamente calibrados, sob luz natural indireta e após escovação supervisionada e secagem dos elementos dentários. Cerca de 20% dos escolares examinados apresentaram fluorose dentária, sendo que 70% com TF 1 e outros 30% distribuídos em diversos graus (TF 2 a 5. Fluorose foi mais prevalente no sexo masculino e em dentes pré-molares. Embora a fluorose dentária observada esteja dentro dos níveis esperados para o teor de fluoretos (0,4 ppm, outras fontes sistêmicas de fluoretos devem ser controladas. A prevalência de fluorose dentária observada não é problema de saúde pública nesta localidade.Several communities in Paraíba have moderate or high levels of fluoride naturally present in the drinking water. A moderate prevalence of dental fluorosis (30-40% has been observed in some areas where the levels of fluoride are regarded as "optimal" for the region (0.6 ppm. The aim of the present study was to determine the prevalence of dental fluorosis in Princesa Isabel, a city with "sub-optimal" fluoride levels (0.4 ppm. The sample comprised 142 schoolchildren (10- to 15-year-old subjects randomly selected and examined by means of the TF (Thylstrup & Fejerskov index. The clinical exams were carried out under indirect natural light by three calibrated examiners. Prior to the examination the teeth were

  10. The effect of organic matter associated with the corrosion products on the corrosion of mild steel in the Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Bhosle, N.B.; Wagh, A.B.

    the corrosion of mild steel and the temperature and dissolved oxygen of seawater. In contrast to this, the corrosion and mild steel was inversely related to the organic carbon and water extractable carbohydrates associated with the corrosion products of mild...

  11. Conservation Research and Development/ New Ultra-Low Carbon High Strength Steels with Improved Bake Hardenability for Enhanced Stretch Formability and Dent Resistance

    Energy Technology Data Exchange (ETDEWEB)

    Anthony J. DeArdo; C. Isaac Garcia

    2003-12-15

    Conservation Research and Development/New Ultra-Low Carbon High Strength Steels with Improved Bake Hardenability for Enhanced Stretch Formability and Dent Resistance. The experimental work can be divided into four phases. In each phase, the materials were received or designed, processed and tested, to evaluate the BH increment or response, as a function of compositions and processing conditions. Microstructural characterization by various techniques was performed in order to gain insights into the mechanisms of flow stress increment by bake hardening.

  12. Prevalência de cárie dentária em Brasília, Brasil Prevalence of dental caries in Brasilia, Brazil

    Directory of Open Access Journals (Sweden)

    José Maria Pacheco de Souza

    1969-12-01

    Full Text Available São apresentados os resultados de um levantamento de cárie dentária, prévio à fluoretação das águas de abastecimento, referentes à Brasília, capital do Brasil.The results of a dental caries survey, before the fluoridation of the water in Brasilia, Brazil's capital, are presented.

  13. How to Improve English Teaching Efficiency to Xinjiang Ethnic High School Stu-dents according to the Basic Idea of the New English Curriculum in High School

    Institute of Scientific and Technical Information of China (English)

    Gulixia Akebaer

    2014-01-01

    Here are some good suggestions on how to improve English teaching efficiency to Xinjiang ethnic high school stu-dents according to the basic ideas of the new English Curriculum in high school , eg: setting down reasonable teaching projects according to the status of Xinjiang ethnic groups;training the students' strong desire to study English;improving teachers' special quality;Make full use of modern teaching methods and so on.

  14. Dentes da desigualdade: marcas bucais da experiência vivida na pobreza pela comunidade do Dendê, Fortaleza, Ceará, Brasil

    Directory of Open Access Journals (Sweden)

    Thiago Pelúcio Moreira

    2007-06-01

    Full Text Available Este estudo antropológico investiga a experiência vivida das doenças bucais no contexto da pobreza no Nordeste brasileiro. Durante seis meses em 2004, foram conduzidas entrevistas etnográficas, narrativas e observação participante com 31 moradores do Dendê, comunidade de baixa renda em Fortaleza, Ceará, analisadas pelo método hermenêutico-dialético. Revelou-se que as precárias condições de vida dificultam priorizar o cuidado em saúde. Embora sofram da dor dentária, ir ao dentista é percebido com um luxo, não um direto do cidadão. O difícil acesso ao serviço e restauração de má qualidade, favorecem a extração dentária como mais resolutiva. A deterioração da saúde bucal é lamentada pelos moradores que buscam ajuda de clínicas populares, políticos e curandeiros. A experiência da doença dentária diferencia de acordo com a classe, deixa marcas bucais da iniqüidade e prejudica a auto-estima e inclusão social. "Tratar" os dentes da desigualdade nesse contexto exige aprofundar a compreensão dos determinantes sociais da saúde, reduzir injustiças no acesso aos serviços de qualidade, remover estigmas que desmoralizam e fortalecer a viva voz da comunidade frente às forças estruturais que afetam sua vida.

  15. Um método para o retratamento da recidiva do desalinhamento dentário A method to re-treat the relapse of dental misalignment

    Directory of Open Access Journals (Sweden)

    David Normando

    2011-10-01

    Full Text Available INTRODUÇÃO: o ortodontista clínico deve esperar alguma perda do alinhamento dentário obtido durante o tratamento ortodôntico nos casos em que a contenção ortodôntica foi suspensa pelo profissional ou perdida pelo paciente. Nessa situação, os pacientes são, frequentemente, relutantes em novamente usar braquetes para retratar o alinhamento dentário perdido após o tratamento. OBJETIVO: esse artigo descreve o uso de uma técnica simples e eficiente para corrigir pequenas alterações do alinhamento dentário. Esse procedimento, inovador e de baixo custo, produz a resolução da recidiva em poucas semanas. A força usada para realinhar os dentes é obtida através de um fio elastomérico transparente amarrado a uma contenção fixa, de vários filamentos, colada às arcadas superior e inferior.INTRODUCTION: The clinician should expect some loss of the dental alignment obtained during orthodontic therapy in the long term in cases in which the orthodontic retainer has been removed by the orthodontist or lost by the patient. In this situation, patients are often reluctant to wear braces again to re-treat anterior misalignment. OBJECTIVE: This report describes the successful use of a simple and effective technique to correct mild changes in the incisor alignment after orthodontic treatment. An innovative and low cost procedure effectively solved relapse of anterior misalignment in 1-2 months. The force used to realign the teeth is obtained through the use of a clear elastomeric thread tied to multistranded upper and lower retainers.

  16. Alterações periodontais durante a movimentação dentária induzida em ratos = Periodontal alterations during induced dental movement in rats

    Directory of Open Access Journals (Sweden)

    Silveira, Daniel

    2006-01-01

    Full Text Available Durante a aplicação de uma força constante e leve, eventos mecânicos e bioquímicos se sucedem, resultando na movimentação dentária. O deslocamento dentário inicial, ainda nos limites da largura alveolar, leva ao extravasamento do fluido do ligamento periodontal, compressão parcial dos vasos sanguíneos e distorção mecânica de fibras e células do ligamento periodontal. As alterações do fluxo sanguíneo acarretam a liberação de mediadores bioquímicos que resultam no recrutamento de osteoclastos e, conseqüentemente, na remodelação óssea. Neste trabalho, os autores se propuseram a avaliar as alterações do periodonto de inserção durante a movimentação dentária induzida em ratos. A amostra foi constituída por nove ratos, divididos em três grupos, cujos primeiros molares superiores direitos foram movimentados utilizando-se uma força de 0,5 N. Os primeiros molares superiores esquerdos desempenharam o papel do grupo controle. Os animais do grupo 1 tiveram seus dentes movimentados por três dias, os do grupo 2, por sete dias e os do grupo 3, por catorze dias. Os cortes histológicos foram corados com hematoxilina e eosina e analisados em microscopia óptica. Verificou-se, durante os primeiros dias de aplicação de força, um predomínio dos fenômenos de neoformação óssea no lado de tração e de reabsorção óssea no lado de pressão

  17. NASA's Corrosion Technology Laboratory at the Kennedy Space Center: Anticipating, Managing, and Preventing Corrosion

    Science.gov (United States)

    Calle, Luz Marina

    2014-01-01

    Corrosion is the degradation of a material that results from its interaction with the environment. The marine environment at NASAs Kennedy Space Center (KSC) has been documented by ASM International (formerly American Society for Metals) as the most corrosive in the United States. With the introduction of the Space Shuttle in 1981, the already highly corrosive conditions at the launch pads were rendered even more severe by the 70 tons of highly corrosive hydrochloric acid that were generated by the solid rocket boosters. Numerous failures at the launch pads are caused by corrosion.The structural integrity of ground infrastructure and flight hardware is critical to the success, safety, cost, and sustainability of space missions. As a result of fifty years of experience with launch and ground operations in a natural marine environment that is highly corrosive, NASAs Corrosion Technology Laboratory at KSC is a major source of corrosion control expertise in the launch and other environments. Throughout its history, the Laboratory has evolved from what started as an atmospheric exposure facility near NASAs launch pads into a world-wide recognized capability that provides technical innovations and engineering services in all areas of corrosion for NASA and external customers.This presentation will provide a historical overview of the role of NASAs Corrosion Technology in anticipating, managing, and preventing corrosion. One important challenge in managing and preventing corrosion involves the detrimental impact on humans and the environment of what have been very effective corrosion control strategies. This challenge has motivated the development of new corrosion control technologies that are more effective and environmentally friendly. Strategies for improved corrosion protection and durability can have a huge impact on the economic sustainability of human spaceflight operations.

  18. Environmental Friendly Coatings and Corrosion Prevention For Flight Hardware Project

    Science.gov (United States)

    Calle, Luz

    2014-01-01

    Identify, test and develop qualification criteria for environmentally friendly corrosion protective coatings and corrosion preventative compounds (CPC's) for flight hardware an ground support equipment.

  19. Protocolo clínico de avaliação e conduta no traumatismo dentário - doi:10.5020/18061230.2009.p120

    Directory of Open Access Journals (Sweden)

    Maria Carolina Bandeira Macena

    2012-01-01

    Full Text Available Objetivo: Apresentar um protocolo clínico, baseado na literatura atual, visando otimizar o atendimento emergencial do trauma dentário nas dentições decídua e permanente. Métodos: estudo de natureza documental, através de revisão da literatura de pesquisas sobre os traumatismos dentários disponíveis nas seguintes bases de dados: mEDLInE, Cochrane, Pubmed, Lilacs, BBO e SCIELO, usando-se os descritores: traumatismo dentário, classificação, diagnóstico e epidemiologia. Os protocolos produzidos pela Associação Internacional de Trauma Dental (IADT e da Academia Americana de Odontopediatria (AAPD também foram revisados. Conclusões: O protocolo clínico representa a evidência mais atual baseada na pesquisa da literatura e na vivência clínica do profissional. As recomendações apresentadas neste trabalho estão de acordo com as relatadas nos protocolos da IADT e AAPD.

  20. 考虑层问作用的冷轧钢卷抗凹性分析%Dent Resistance Analysis of Cold Rolled Steel Coil Considering Interlayer Effect

    Institute of Scientific and Technical Information of China (English)

    刘海江; 郭瑞玲

    2012-01-01

    针对冷轧钢卷包装中多层材料的接触变形问题,对钢卷包装系统的抗凹性进行了分析与研究;建立了考虑层间作用的钢卷包装系统的力学模型,计算和分析了钢卷的变形和应力,应用HYPERMESH与ANSYS/LS-DYNA对钢卷抗凹性模型进行了有限元仿真;最后进行了抗凹性模型的冲击试验,验证了有限元仿真计算结果,可为钢卷包装工艺设计提供理论依据。%For solving the multi-layer contact deformation problem of cold rolled steel coil, dent resistance of steel coil packaging system was analyzed and studied. Mechanical model of steel coil packaging system considering interlayer effect was established and the strain and stress of the steel colt was calculated and analyzed. FEM simulation of dent resistance of the steel coil was carried out by using HYPERMESH and ANSYS/LS-DYNA. An impact test of the dent resistance model was carried out to verify the FEM simulation. The purpose was to provide theory basis for steel coil packaging process design.

  1. Prevalência de cárie em dentes permanentes de escolares do Município de São Paulo, SP, 1970-1996

    Directory of Open Access Journals (Sweden)

    Paulo C Narvai

    2000-04-01

    Full Text Available OBJETIVO: Estudar a evolução da prevalência de cárie em dentes permanentes da população infantil do Município de São Paulo, SP, no período 1970-1996, com base em levantamento epidemiológico em escolares das redes pública e privada de ensino. MÉTODOS: Utilizando metodologia recomendada pela Organização Mundial da Saúde, foram examinados 2.491 escolares de 103 unidades das redes de ensino público e privado. Foi obtida amostra probabilística, com base no cadastro das escolas do município. Os elementos amostrais foram identificados ao acaso. RESULTADOS: Observou-se que de uma situação de prevalência "muito alta" de cárie dentária nos anos 60 e 70, a população de referência evoluiu positivamente, na idade-índice de 12 anos, para um quadro de "baixa" prevalência. CONCLUSÃO: Entre 1986 e 1996 o declínio na cárie dentária, aos 12 anos de idade, foi da ordem de 68,2% entre escolares do Município de São Paulo.

  2. Prevalência de cárie em dentes permanentes de escolares do Município de São Paulo, SP, 1970-1996

    Directory of Open Access Journals (Sweden)

    Narvai Paulo C

    2000-01-01

    Full Text Available OBJETIVO: Estudar a evolução da prevalência de cárie em dentes permanentes da população infantil do Município de São Paulo, SP, no período 1970-1996, com base em levantamento epidemiológico em escolares das redes pública e privada de ensino. MÉTODOS: Utilizando metodologia recomendada pela Organização Mundial da Saúde, foram examinados 2.491 escolares de 103 unidades das redes de ensino público e privado. Foi obtida amostra probabilística, com base no cadastro das escolas do município. Os elementos amostrais foram identificados ao acaso. RESULTADOS: Observou-se que de uma situação de prevalência "muito alta" de cárie dentária nos anos 60 e 70, a população de referência evoluiu positivamente, na idade-índice de 12 anos, para um quadro de "baixa" prevalência. CONCLUSÃO: Entre 1986 e 1996 o declínio na cárie dentária, aos 12 anos de idade, foi da ordem de 68,2% entre escolares do Município de São Paulo.

  3. Civil Engineering Corrosion Control. Volume 1. Corrosion Control - General

    Science.gov (United States)

    1975-01-01

    source, consisting of " artificial " anodes energized by rectified A.C. or galvanic voltage, is used. Where current leaves a metal surface, corrosion occurs...additional data. 2 Losses of weight sustained by 5.1- by 10.2- cm. (2- by 4- inc.) specimens made of open- hearth iron (0.007 percent copper) are used as a...Al(OH)3 ) that forms, tending to prevent further cor- rosion. This film can be artificially induced by anodizing, passing electric current through

  4. High Temperature Corrosion under Laboratory Conditions Simulating Biomass-Firing: A Comprehensive Characterization of Corrosion Products

    DEFF Research Database (Denmark)

    Okoro, Sunday Chukwudi; Montgomery, Melanie; Jappe Frandsen, Flemming

    2014-01-01

    characterization of the corrosion products. The corrosion products consisted of three layers: i) the outermost layer consisting of a mixed layer of K2SO4 and FexOy on a partly molten layer of the initial deposit, ii) the middle layer consists of spinel (FeCr2O4) and Fe2O3, and iii) the innermost layer is a sponge......-like Ni3S2 containing layer. At the corrosion front, Cl-rich protrusions were observed. Results indicate that selective corrosion of Fe and Cr by Cl, active oxidation and sulphidation attack of Ni are possible corrosion mechanisms....

  5. Colorimetric visualization of tin corrosion: A method for early stage corrosion detection on printed circuit boards

    DEFF Research Database (Denmark)

    Verdingovas, Vadimas; Jellesen, Morten Stendahl; Ambat, Rajan

    2017-01-01

    A majority of printed circuit board surfaces are covered with tin, therefore tin corrosion under humid conditions and movement of tin ions under the influence of an electric field plays an important role in the corrosion failure development. Tracking tin corrosion products spread on the printed...... a colorimetric tin ion indicator applied as a gel. The examples provided in this paper include visualization of corrosion caused by weak organic acids found in solder fluxes, corrosion profiling on the PCBAs after climatic device level testing, and failure analysis of field returns....

  6. Screening of soil corrosivity by field testing: Results and design of an electrochemical soil corrosion probe

    DEFF Research Database (Denmark)

    Nielsen, Lars vendelbo; Bruun, Niels Kåre

    1996-01-01

    The corrosivity of different types of soil have been assessed by exposing carbon-steel plates at 50 different locations in Denmark for an extended period of time. The investigations included weight loss measurements and analysis of the chemical compositions of the corrosion products formed...... on the plates during exposure. An electrochemical soil corrosion probe has been designed and manufactured allowing for simultaneous measurements of several qauntities to predict corrosion. The probe consists of individual sections capable of measuring redox-potential, corrosion potential, soil resistivity...

  7. High Temperature Corrosion under Laboratory Conditions Simulating Biomass-Firing: A Comprehensive Characterization of Corrosion Products

    DEFF Research Database (Denmark)

    Okoro, Sunday Chukwudi; Montgomery, Melanie; Jappe Frandsen, Flemming

    2014-01-01

    characterization of the corrosion products. The corrosion products consisted of three layers: i) the outermost layer consisting of a mixed layer of K2SO4 and FexOy on a partly molten layer of the initial deposit, ii) the middle layer consists of spinel (FeCr2O4) and Fe2O3, and iii) the innermost layer is a sponge......-like Ni3S2 containing layer. At the corrosion front, Cl-rich protrusions were observed. Results indicate that selective corrosion of Fe and Cr by Cl, active oxidation and sulphidation attack of Ni are possible corrosion mechanisms....

  8. Novel Corrosion Sensor for Vision 21 Systems

    Energy Technology Data Exchange (ETDEWEB)

    Heng Ban; Bharat Soni

    2007-03-31

    Advanced sensor technology is identified as a key component for advanced power systems for future energy plants that would have virtually no environmental impact. This project intends to develop a novel high temperature corrosion sensor and subsequent measurement system for advanced power systems. Fireside corrosion is the leading mechanism for boiler tube failures and has emerged to be a significant concern for current and future energy plants due to the introduction of technologies targeting emissions reduction, efficiency improvement, or fuel/oxidant flexibility. Corrosion damage can lead to catastrophic equipment failure, explosions, and forced outages. Proper management of corrosion requires real-time indication of corrosion rate. However, short-term, on-line corrosion monitoring systems for fireside corrosion remain a technical challenge to date due to the extremely harsh combustion environment. The overall goal of this project is to develop a technology for on-line fireside corrosion monitoring. This objective is achieved by the laboratory development of sensors and instrumentation, testing them in a laboratory muffle furnace, and eventually testing the system in a coal-fired furnace. This project successfully developed two types of sensors and measurement systems, and successful tested them in a muffle furnace in the laboratory. The capacitance sensor had a high fabrication cost and might be more appropriate in other applications. The low-cost resistance sensor was tested in a power plant burning eastern bituminous coals. The results show that the fireside corrosion measurement system can be used to determine the corrosion rate at waterwall and superheater locations. Electron microscope analysis of the corroded sensor surface provided detailed picture of the corrosion process.

  9. Corrosion of RoHS-Compliant Surface Finishes in Corrosive Mixed Flowing Gas Environments

    Science.gov (United States)

    Hannigan, K.; Reid, M.; Collins, M. N.; Dalton, E.; Xu, C.; Wright, B.; Demirkan, K.; Opila, R. L.; Reents, W. D.; Franey, J. P.; Fleming, D. A.; Punch, J.

    2012-03-01

    Recently, the corrosion resistance of printed wiring board (PWB) finishes has generated considerable interest due to field failures observed in various parts of the world. This study investigates the corrosion issues associated with the different lead-free PWB surface finishes. Corrosion products on various PWB surface finishes generated in mixed flowing gas (MFG) environments were studied, and analysis techniques such as scanning electron microscopy, energy-dispersive x-ray, x-ray diffraction, focused ion beam, and scanning Auger microscopy were used to quantify the corrosion layer thickness and determine the composition of corrosion products. The corrosion on organic solderability preservative samples shows similar corrosion products to bare copper and is mainly due to direct attack of copper traces by corrosive gases. The corrosion on electroless nickel immersion gold occurs primarily through the porosity in the film and is accelerated by the galvanic potential between gold and copper; similar results were observed on immersion silver. Immersion tin shows excellent corrosion resistance due to its inherent corrosion resistance in the MFG environment as well as the opposite galvanic potential between tin and copper compared with gold or silver and copper.

  10. Effect of Flow Velocity on Corrosion Rate and Corrosion Protection Current of Marine Material

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seong Jong [Kunsan National University, Kunsan (Korea, Republic of); Han, Min Su; Jang, Seok Ki; Kim, Seong Jong [Mokpo National Maritime University, Mokpo (Korea, Republic of)

    2015-10-15

    In spite of highly advanced paint coating techniques, corrosion damage of marine metal and alloys increase more and more due to inherent micro-cracks and porosities in coatings formed during the coating process. Furthermore, flowing seawater conditions promote the breakdown of the protective oxide of the materials introducing more oxygen into marine environments, leading to the acceleration of corrosion. Various corrosion protection methods are available to prevent steel from marine corrosion. Cathodic protection is one of the useful corrosion protection methods by which the potential of the corroded metal is intentionally lowered to an immune state having the advantage of providing additional protection barriers to steel exposed to aqueous corrosion or soil corrosion, in addition to the coating. In the present investigation, the effect of flow velocity was examined for the determination of the optimum corrosion protection current density in cathodic protection as well as the corrosion rate of the steel. It is demonstrated from the result that the material corrosion under dynamic flowing conditions seems more prone to corrosion than under static conditions.

  11. Corrosion Products and Formation Mechanism During Initial Stage of Atmospheric Corrosion of Carbon Steel

    Institute of Scientific and Technical Information of China (English)

    XIAO Kui; DONG Chao-fang; LI Xiao-gang; WANG Fu-ming

    2008-01-01

    The formation and development of corrosion products on carbon steel surface during the initial stage of atmospheric corrosion in a laboratory simulated environment have been studied by scanning electron microscopy (SEM)and Raman spectroscopy.The results showed that two different shapes of corrosion products,that is,ring and chain,were formed in the initial stage of corrosion.MnS clusters were found in the nuclei of corrosion products at the active local corrosion sites.The ring-shaped products were composed of lepidocrocite (γ-FeOOH) and maghemite(γ-Fe2 O3) transformed from lepidocrocite.The chain-type products were goethite (α-FeOOH).A formation mechanism of the corrosion products is proposed.

  12. Corrosion Mechanism of Corrosion-Resistant Steel Developed for Bottom Plate of Cargo Oil Tanks

    Institute of Scientific and Technical Information of China (English)

    Feilong SUN; Xiaogang LI; Fan ZHANG; Xuequn CHENG; Cheng ZHOU; Nianchun WU; Yuqun YIN

    2013-01-01

    A new type of corrosion-resistant steel consisting of ferrite and bainite phases was developed for cargo oil tanks of crude oil tankers.The corrosion rate of this new steel was 0.22 mm/a,which was equivalent to ca.1/5 of the criterion (≤ 1 mm/a) for corrosion-resistant steels.The composition and element distribution of the corrosion products were investigated by micro-Raman spectrometry and energy dispersive spectrometer.The results demonstrated that the corrosion product was composed of α-FeOOH,Fe3O4 and a continuous Cu enrichment layer.This kind of corrosion product was protective to the steel matrix and accounted for the enhancement of the corrosion resistance of the new developed steel.

  13. Field corrosion characterization of soil corrosion of X70 pipeline steel in a red clay soil

    Institute of Scientific and Technical Information of China (English)

    Shengrong Wang; Cuiwei Dun; Xiaogang Li; Zhiyong Liunn; Min Zhu; Dawei Zhang

    2015-01-01

    The corrosion behavior of X70 pipeline steel buried in red soil environment has been studied. The surface morphology and elemental distribution were determined by scanning electron microscopy (SEM),energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). The corrosion kinetics was evaluated by weight loss measurement. The results show that in red soil, the corrosion rate of X70 steel decreases with time, and follows the exponential decay law. General corrosion with non-uniform and localized pitting occurred on the steel surface.α-FeOOH was the dominate products during corrosion in whole buried periods, and the corrosion products exhibited well protective properties. The potentiodynamic polarization tests revealed that icorr decreased with time, indicating the improvement of corrosion resistance. The results of Electrochemical impendence spectroscopy (EIS) are consistent with potentiodynamic polarization tests.

  14. Field corrosion characterization of soil corrosion of X70 pipeline steel in a red clay soil

    Directory of Open Access Journals (Sweden)

    Shengrong Wang

    2015-06-01

    Full Text Available The corrosion behavior of X70 pipeline steel buried in red soil environment has been studied. The surface morphology and elemental distribution were determined by scanning electron microscopy (SEM,energy dispersive X-ray spectroscopy (EDS, and X-ray diffraction (XRD. The corrosion kinetics was evaluated by weight loss measurement. The results show that in red soil, the corrosion rate of X70 steel decreases with time, and follows the exponential decay law. General corrosion with non-uniform and localized pitting occurred on the steel surface. α-FeOOH was the dominate products during corrosion in whole buried periods, and the corrosion products exhibited well protective properties. The potentiodynamic polarization tests revealed that icorr decreased with time, indicating the improvement of corrosion resistance. The results of Electrochemical impendence spectroscopy (EIS are consistent with potentiodynamic polarization tests.

  15. Effects of alternating magnetic field on the corrosion rate and corrosion products of copper

    Institute of Scientific and Technical Information of China (English)

    GUO Bin; ZHANG Peng; JIN Yongping; CHENG Shukang

    2008-01-01

    The effects of alternating magnetic field on the corrosion morphologies, corrosion rate, and corrosion products of copper in 3.5% NaCl solution, sea water, and magnetized sea water were investigated using electrochemical test, scanning electron microscopy/energy dispersive analysis system of X-ray (SEM/EDAX), and X-ray diffraction (XRD). The results show that the corrosion rate of copper in magnetized sea water is minimal. Moreover, the surface of the specimen in magnetized sea water is uniform and compact as compared with those in 3.5% NaCl solution and sea water. The corrosion products of copper in magnetized sea water are mainly Cu2O and CuCl2. However, the corrosion products in sea water are CuCl, Cu2Cl(OH)3, and FeCl3·6H2O. The electrochemical corrosion mechanisms of copper in the three media were also discussed.

  16. Corrosivity of paper mill effluent and corrosion performance of stainless steel.

    Science.gov (United States)

    Ram, Chhotu; Sharma, Chhaya; Singh, A K

    2015-01-01

    Present study relates to the corrosivity of paper mill effluent and corrosion performance of stainless steel (SS) as a construction material for the effluent treatment plant (ETP). Accordingly, immersion test and electrochemical polarization tests were performed on SS 304 L, 316 L and duplex 2205 in paper mill effluent and synthetic effluent. This paper presents electrochemical polarization measurements, performed for the first time to the best of the authors' information, to see the influence of chlorophenols on the corrosivity of effluents. The corrosivity of the effluent was observed to increase with the decrease in pH and increase in Cl- content while the addition of SO4- tends to inhibit corrosion. Mill effluent was found to be more corrosive as compared to synthetic effluent and has been attributed to the presence of various chlorophenols. Corrosion performance of SS was observed to govern by the presence of Cr, Mo and N contents.

  17. Vitalidade pulpar em dentes portadores de brackets ortodônticos: apresentação de uma técnica = Pulp vitality test on teeth having orthodontics brackets: technique presentation

    Directory of Open Access Journals (Sweden)

    Barletta, Fernando Branco

    2007-01-01

    Full Text Available O presente trabalho teve como objetivo avaliar a confiabilidade do teste de vitalidade pulpar com o gás refrigerante tetrafluoretano (CS 68 em dentes portadores de brackets ortodônticos. Foram selecionados 37 pacientes de clínica privada, com faixa etária entre 12 e 60 anos de idade. O teste de vitalidade pulpar foi realizado na face palatina ou lingual, na região de terço médio dos dentes, abaixo do cíngulo, nos grupos dentários dos incisivos, caninos e pré-molares superiores e inferiores, totalizando 402 dentes. Quando a resposta de sensibilidade pulpar era negativa ao teste, o mesmo era repetido; confirmando-se o resultado como negativo, realizavase uma tomada radiográfica pela técnica periapical do dente em questão. Os resultados evidenciaram 4 elementos dentários com resposta negativa ao teste de vitalidade pulpar, sendo 3 pré-molares e um incisivo central. A resposta dos demais foi positiva ao teste. Diante dos resultados, verificou-se que a aplicação do teste de vitalidade pulpar pela face palatina em pacientes portadores de brackets ortodônticos constitui-se em uma alternativa segura e confiável

  18. Review of studies on corrosion of magnesium alloys

    Institute of Scientific and Technical Information of China (English)

    ZENG Rong-chang; ZHANG jin; HUANG Wei-jiu; W. DIETZEL; K. U. KAINER; C. BLAWERT; KE Wei

    2006-01-01

    This review provided some recent progress of the research on corrosion mechanisms of magnesium and its alloys and a basis for follow-on research. Galvanic corrosion,pitting corrosion,intergranular corrosion (IGC),filiform corrosion,crevice corrosion,stress corrosion cracking (SCC),and corrosion fatigue (CF) were discussed. The influence of metallurgical factors such as alloying elements,microstructure and secondary phases,processing factors such as heat treatment and weld,and environmental factors including temperature,relative humidity,solution pH values and concentration on corrosion were discussed. In particular,a mechanism of pitting corrosion caused by AlMn particles was proposed. The corrosion properties of AZ91D weld material were investigated.

  19. Inhibitor treatment program for chlorine dioxide corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Edmondson, J.G.; Holder, E.P.

    1991-11-12

    This patent describes a method of inhibiting corrosion by chlorine dioxide in oil field waterflood systems by adding a sufficient amount of a corrosion inhibiting composition. It comprises a phosphonate, a copolymer consisting of repeating units of acrylic acid/allyl hydroxy propyl sulfonate ether, and a permangante.

  20. Computer-Aided Corrosion Program Management

    Science.gov (United States)

    MacDowell, Louis

    2010-01-01

    This viewgraph presentation reviews Computer-Aided Corrosion Program Management at John F. Kennedy Space Center. The contents include: 1) Corrosion at the Kennedy Space Center (KSC); 2) Requirements and Objectives; 3) Program Description, Background and History; 4) Approach and Implementation; 5) Challenges; 6) Lessons Learned; 7) Successes and Benefits; and 8) Summary and Conclusions.

  1. Aircraft Integral Fuel Tank Corrosion Study

    Science.gov (United States)

    2007-11-02

    biology of Amorphoteca resinae . Materials und Organismen, 6, (3), p. 161, (1971). 8. D. Cabral. Corrosion by microorganisms of jet aircraft integral fuel...the mycelium of the fungus Hormoconis resinae in the MIC of Al alloys. Proc. XI Int. Corrosion Congress, Houston, USA, 5B, p. 3773, (1993). 14. M

  2. Corrosion problems with aqueous coolants, final report

    Energy Technology Data Exchange (ETDEWEB)

    Diegle, R B; Beavers, J A; Clifford, J E

    1980-04-11

    The results of a one year program to characterize corrosion of solar collector alloys in aqueous heat-transfer media are summarized. The program involved a literature review and a laboratory investigation of corrosion in uninhibited solutions. It consisted of three separate tasks, as follows: review of the state-of-the-art of solar collector corrosion processes; study of corrosion in multimetallic systems; and determination of interaction between different waters and chemical antifreeze additives. Task 1 involved a comprehensive review of published literature concerning corrosion under solar collector operating conditions. The reivew also incorporated data from related technologies, specifically, from research performed on automotive cooling systems, cooling towers, and heat exchangers. Task 2 consisted of determining the corrosion behavior of candidate alloys of construction for solar collectors in different types of aqueous coolants containing various concentrations of corrosive ionic species. Task 3 involved measuring the degradation rates of glycol-based heat-transfer media, and also evaluating the effects of degradation on the corrosion behavior of metallic collector materials.

  3. Corrosion effects on soda lime glass

    NARCIS (Netherlands)

    Veer, F.A.; Rodichev, Y.M.

    2010-01-01

    Although soda lime glass is the most common used transparent material in architecture, little is known about the corrosion effects on long term strength and the interaction between corrosion and defects. Extensive testing on soda lime bars under different environmental conditions and different degre

  4. Biobased polymers for corrosion protection of metals

    Science.gov (United States)

    Anticorrosive biobased polymers were developed in our lab. We isolated an exopolysaccharide produced by a microbe that, when coated on metal substrates, exhibited unique corrosion inhibition. Corrosion is a worldwide problem and impacts the economy, jeopardizes human health and safety, and impedes t...

  5. Erosion–corrosion and corrosion properties of DLC coated low temperature Erosion–corrosion and corrosion properties of DLC coated low temperature

    DEFF Research Database (Denmark)

    Jellesen, Morten Stendahl; Christiansen, Thomas; Hilbert, Lisbeth Rischel

    2009-01-01

    of AISI 316 as substrate for DLC coatings are investigated. Corrosion and erosion–corrosion measurements were carried out on low temperature nitrided stainless steel AISI 316 and on low temperature nitrided stainless steel AISI 316 with a top layer of DLC. The combination of DLC and low temperature...

  6. Factors affecting the corrosivity of pulping liquors

    Science.gov (United States)

    Hazlewood, Patrick Evan

    Increased equipment failures and the resultant increase in unplanned downtime as the result of process optimization programs continue to plague pulp mills. The failures are a result of a lack of understanding of corrosion in the different pulping liquors, specifically the parameters responsible for its adjustment such as the role and identification of inorganic and organic species. The current work investigates the role of inorganic species, namely sodium hydroxide and sodium sulfide, on liquor corrosivity at a range of process conditions beyond those currently experienced in literature. The role of sulfur species, in the activation of corrosion and the ability of hydroxide to passivate carbon steel A516-Gr70, is evaluated with gravimetric and electrochemical methods. The impact of wood chip weathering on process corrosion was also evaluated. Results were used to identify black liquor components, depending on the wood species, which play a significant role in the activation and inhibition of corrosion for carbon steel A516-Gr70 process equipment. Further, the effect of black liquor oxidation on liquor corrosivity was evaluated. Corrosion and stress corrosion cracking performance of selected materials provided information on classes of materials that may be reliably used in aggressive pulping environments.

  7. The dual role of microbes in corrosion

    NARCIS (Netherlands)

    Kip, D.J.; Van Veen, J.A.

    2015-01-01

    Corrosion is the result of a series of chemical, physical and (micro) biological processes leading to the deterioration of materials such as steel and stone. It is a world-wide problem with great societal and economic consequences. Current corrosion control strategies based on chemically produced pr

  8. Dissolution properties of cerium dibutylphosphate corrosion inhibitors

    NARCIS (Netherlands)

    Soestbergen, M. van; Erich, S.J.F.; Huinink, H.P.; Adan, O.C.G.

    2013-01-01

    The corrosion inhibitor cerium dibutylphosphate, Ce(dbp)3, prevents corrosion by cerium and dbp deposition at the alkaline cathode and acidic anode respectively. The pH dependent Ce(dbp)3 solubility seems to play an essential role in the inhibition degree. We found that Ce(dbp) 3 scarcely dissolves

  9. EXTRACT OF COMBRETUM MICRANTHUM AS CORROSION ...

    African Journals Online (AJOL)

    user

    2016-10-04

    Oct 4, 2016 ... Aluminum and aluminum alloys lend themselves to many engineering ... Table 1: Elemental composition of the alloy Al-Si-Mg. Element. Si. Mg. Cu. Zn. Al. Composition (wt. ..... microstructure of the control Al- Si- Mg alloy with the lowest C.R in the ... silicate as a corrosion inhibitor for iron and zinc,. Corrosion ...

  10. Vibrational Spectroscopy in Studies of Atmospheric Corrosion

    Directory of Open Access Journals (Sweden)

    Saman Hosseinpour

    2017-04-01

    Full Text Available Vibrational spectroscopy has been successfully used for decades in studies of the atmospheric corrosion processes, mainly to identify the nature of corrosion products but also to quantify their amounts. In this review article, a summary of the main achievements is presented with focus on how the techniques infrared spectroscopy, Raman spectroscopy, and vibrational sum frequency spectroscopy can be used in the field. Several different studies have been discussed where these instruments have been used to assess both the nature of corrosion products as well as the properties of corrosion inhibitors. Some of these techniques offer the valuable possibility to perform in-situ measurements in real time on ongoing corrosion processes, which allows the kinetics of formation of corrosion products to be studied, and also minimizes the risk of changing the surface properties which may occur during ex-situ experiments. Since corrosion processes often occur heterogeneously over a surface, it is of great importance to obtain a deeper knowledge about atmospheric corrosion phenomena on the nano scale, and this review also discusses novel vibrational microscopy techniques allowing spectra to be acquired with a spatial resolution of 20 nm.

  11. Geothermal drill pipe corrosion test plan

    Energy Technology Data Exchange (ETDEWEB)

    Caskey, B.C.; Copass, K.S.

    1980-12-01

    Plans are presented for conducting a field test of drill pipe corrosion, comparing air and nitrogen as drilling fluids. This test will provide data for evaluating the potential of reducing geothermal well drilling costs by extending drill pipe life and reducing corrosion control costs. The 10-day test will take place during fall 1980 at the Baca Location in Sandoval County, New Mexico.

  12. Solutions of corrosion Problems in advanced Technologies

    DEFF Research Database (Denmark)

    Montgomery, Melanie; Karlsson, Asger

    1999-01-01

    were investigated using light optical and scanning electron microscopy. The ferritic steels suffered from corrosion mainly via material loss. The austenitic steels suffered from predominantly selective corrosion resulting in chromium depletion from the alloy. A clear trend was observed that selective...

  13. Corrosion effects on soda lime glass

    NARCIS (Netherlands)

    Veer, F.A.; Rodichev, Y.M.

    2010-01-01

    Although soda lime glass is the most common used transparent material in architecture, little is known about the corrosion effects on long term strength and the interaction between corrosion and defects. Extensive testing on soda lime bars under different environmental conditions and different

  14. Remote computer monitors corrosion protection system

    Energy Technology Data Exchange (ETDEWEB)

    Kendrick, A.

    Effective corrosion protection with electrochemical methods requires some method of routine monitoring that provides reliable data that is free of human error. A test installation of a remote computer control monitoring system for electrochemical corrosion protection is described. The unit can handle up to six channel inputs. Each channel comprises 3 analog signals and 1 digital. The operation of the system is discussed.

  15. Vibrational Spectroscopy in Studies of Atmospheric Corrosion

    Science.gov (United States)

    Hosseinpour, Saman; Johnson, Magnus

    2017-01-01

    Vibrational spectroscopy has been successfully used for decades in studies of the atmospheric corrosion processes, mainly to identify the nature of corrosion products but also to quantify their amounts. In this review article, a summary of the main achievements is presented with focus on how the techniques infrared spectroscopy, Raman spectroscopy, and vibrational sum frequency spectroscopy can be used in the field. Several different studies have been discussed where these instruments have been used to assess both the nature of corrosion products as well as the properties of corrosion inhibitors. Some of these techniques offer the valuable possibility to perform in-situ measurements in real time on ongoing corrosion processes, which allows the kinetics of formation of corrosion products to be studied, and also minimizes the risk of changing the surface properties which may occur during ex-situ experiments. Since corrosion processes often occur heterogeneously over a surface, it is of great importance to obtain a deeper knowledge about atmospheric corrosion phenomena on the nano scale, and this review also discusses novel vibrational microscopy techniques allowing spectra to be acquired with a spatial resolution of 20 nm. PMID:28772781

  16. The dual role of microbes in corrosion

    NARCIS (Netherlands)

    Kip, D.J.; Van Veen, J.A.

    2015-01-01

    Corrosion is the result of a series of chemical, physical and (micro) biological processes leading to the deterioration of materials such as steel and stone. It is a world-wide problem with great societal and economic consequences. Current corrosion control strategies based on chemically produced

  17. Corrosion Behaviour of New Zr Alloys

    DEFF Research Database (Denmark)

    Tolksdorf, E.

    1974-01-01

    Corrosion studies have indicated that the most promising replacements for Zicaloy-2 are ZrCrFe, ZrVFe and probably ZrNbTa, provided they are in their optimized condition. These alloys are conventionally manufactured alloys. An internally oxidized ZrMgO alloy is even superior, from the corrosion...

  18. Electrochemical corrosion measurements on noble electrodeposits

    DEFF Research Database (Denmark)

    Christoffersen, Lasse; Maahn, Ernst Emanuel

    1998-01-01

    Novel electrodeposits are compared with hard chrome and electroless Ni-P with respect to production, corrosion resistance and hardness.......Novel electrodeposits are compared with hard chrome and electroless Ni-P with respect to production, corrosion resistance and hardness....

  19. The Corrosion and Corrosion Fatigue Behavior of Nickel Based Alloy Weld Overlay and Coextruded Claddings

    Science.gov (United States)

    Stockdale, Andrew

    The use of low NOx boilers in coal fired power plants has resulted in sulfidizing corrosive conditions within the boilers and a reduction in the service lifetime of the waterwall tubes. As a solution to this problem, Ni-based weld overlays are used to provide the necessary corrosion resistance however; they are susceptible to corrosion fatigue. There are several metallurgical factors which give rise to corrosion fatigue that are associated with the localized melting and solidification of the weld overlay process. Coextruded coatings offer the potential for improved corrosion fatigue resistance since coextrusion is a solid state coating process. The corrosion and corrosion fatigue behavior of alloy 622 weld overlays and coextruded claddings was investigated using a Gleeble thermo-mechanical simulator retrofitted with a retort. The experiments were conducted at a constant temperature of 600°C using a simulated combustion gas of N2-10%CO-5%CO2-0.12%H 2S. An alternating stress profile was used with a minimum tensile stress of 0 MPa and a maximum tensile stress of 300 MPa (ten minute fatigue cycles). The results have demonstrated that the Gleeble can be used to successfully simulate the known corrosion fatigue cracking mechanism of Ni-based weld overlays in service. Multilayer corrosion scales developed on each of the claddings that consisted of inner and outer corrosion layers. The scales formed by the outward diffusion of cations and the inward diffusion of sulfur and oxygen anions. The corrosion fatigue behavior was influenced by the surface finish and the crack interactions. The initiation of a large number of corrosion fatigue cracks was not necessarily detrimental to the corrosion fatigue resistance. Finally, the as-received coextruded cladding exhibited the best corrosion fatigue resistance.

  20. A STUDY OF ROOT CANAL MORPHOLOGY OF Cebus apella TEETH ESTUDO ANATÔMICO DO CANAL RADICULAR DE DENTES DE Cebus apella

    Directory of Open Access Journals (Sweden)

    Priscilla Rocha Afonso

    2008-12-01

    Full Text Available Realizou-se um estudo anatômico em dentes do Cebus apella, para análise da anatomia interna do canal radicular dessa espécie, normatizando seu uso como modelo experimental. Utilizaram-se doze animais adultos. Após a remoção do tecido orgânico, os dentes foram removidos, seccionados e fotografados, sendo analisados com um estereomicroscópio. Os resultados mostraram que os dentes apresentaram características semelhantes às dos seres humanos, mas com algumas peculiaridades, tais como: a anatomia do canal radicular variou de oval para circular; nos caninos inferiores, os canais são semelhantes a um rim, o que reflete o contorno externo da raiz; nos molares superiores, os canais mesiobucal e distobucal são ovais, seguindo o contorno geral do dente. Os autores concluem que esta espécie pode ser utilizada como modelo em pesquisas odontológicas, principalmente em estudos do tratamento do sistema de canal radicular.

    PALAVRAS-CHAVES: Anatomia, dentes, Cebus apella. An anatomic study of Cebus apella root teeth was performed to analyze the internal anatomy of permanent dentition, normalizing its use as experimental model endodontic research. Twelve adult animals were used in this study. After the removal of the organic tissue, the all teeth were removed, sectioned, analyzed and photographed with a stereomicroscope. The results showed that the anatomy of root canal of this species are similar to human dental anatomy, considering the shape, pathway and number of canals, but with some peculiarities, such as: the root canal anatomy varied from oval to circular; in the lower canines, the canals are resembled a kidney, reflecting the outside contour of the root; in the upper molars, the mesiobuccal and distobuccal canals are oval, following the general contour of the tooth. The authors conclude that this primate can be applied as models for study of root canal treatment in human beings, in special the upper central and lateral incisors

  1. Estudo sobre a fluorose dentária num município do sul do Brasil Study on the dental fluorosis in a Southern city of Brazil

    Directory of Open Access Journals (Sweden)

    Lilian Rigo

    2010-06-01

    Full Text Available O objetivo deste estudo foi determinar a frequência e a severidade da fluorose dentária, bem como verificar possíveis associações com cárie dentária, sexo, idade, etnia e localização geográfica das escolas, nos escolares de doze e de quinze a dezenove anos de idade do município de Passo Fundo, Rio Grande do Sul. A população estudada foi constituída por 633 escolares, de ambos os sexos, matriculados em vinte e seis escolas municipais de ensino fundamental, nas idades índices citadas. Os exames foram realizados por três examinadores previamente calibrados para a aplicação do Índice de Dean. A prevalência de fluorose dentária no grupo estudado foi de 32,8%. O grau predominante foi o muito leve (78,4%, seguido pelos graus leve (11,1%, questionável (8,7% e moderado (1,9%. A prevalência de fluorose dentária na população estudada foi expressiva, embora com um baixo grau de severidade. Os fatores idade e índice de cárie dentária mostraram-se relacionados à variável resposta.The objective of this article is to determine the frequency and severity of dental fluorosis, as well as to verify possible associations with dental caries, gender, age, ethnicity and geographic location of schools in schoolchildren of 12 years old and from 15 to 19 years in the city of Passo Fundo, Rio Grande do Sul State, Brazil. A total of 633 schoolchildren of both genders at the cited ages, enrolled in 26 public schools of fundamental teaching were involved in the epidemiological study. The inspection was performed by three examiners previously trained to apply Dean's Index. The prevalence of dental fluorosis in the studied group was of 32.8%. Predominant degree was the very light (78.4%, followed by light (11.1%, questionable (8.7% and moderate (1.9%. The prevalence of dental fluorosis was expressive in this population, however, with a low degree of severity. Factors such as age and dental caries index showed to be related to the variable response.

  2. General Corrosion and Localized Corrosion of the Drip Shield

    Energy Technology Data Exchange (ETDEWEB)

    F. Hua; K. Mon

    2003-06-24

    The recommended waste package (WP) design is described in BSC (2001a). The design includes a double-wall WP underneath a protective drip shield (DS) (BSC 2003a). The purpose of the process-level models developed in this report is to model dry oxidation (DOX), general corrosion (GC) and localized corrosion (LC) of the DS plate material, which is made of Ti Grade 7. The DS design also includes structural supports fabricated from Ti Grade 24. Degradation of Ti Grade 24 is not considered in this report. The DS provides protection for the waste package outer barrier (WPOB) both as a barrier to seepage water contact and a physical barrier to potential rockfall. This Model Report (MR) serves as a feed to the Integrated Waste Package Degradation Model (IWPD) analyses, and was developed in accordance with the Technical Work Plan (TWP) (BSC 2002a). The models contained in this report serve as a basis to determine whether or not the performance requirements for the DS can be met.

  3. Steam generator corrosion 2007; Dampferzeugerkorrosion 2007

    Energy Technology Data Exchange (ETDEWEB)

    Born, M. (ed.)

    2007-07-01

    Between 8th and 9th November, 2007, SAXONIA Standortentwicklungs- und -verwertungsgesellschaft GmbH (Freiberg, Federal Republic of Germany) performed the 3rd Freiberger discussion conference ''Fireside boiler corrosion''. The topics of the lectures are: (a) Steam generator corrosion - an infinite history (Franz W. Alvert); (b) CFD computations for thermal waste treatment plants - a contribution for the damage recognition and remedy (Klaus Goerner, Thomas Klasen); (c) Experiences with the use of corrosion probes (Siegfried R. Horn, Ferdinand Haider, Barbara Waldmann, Ragnar Warnecke); (d) Use of additives for the limitation of the high temperature chlorine corrosion as an option apart from other measures to the corrosion protection (Wolfgang Spiegel); (e) Current research results and aims of research with respect to chlorine corrosion (Ragnar Warnecke); (f) Systematics of the corrosion phenomena - notes for the enterprise and corrosion protection (Thomas Herzog, Wolfgang Spiegel, Werner Schmidl); (g) Corrosion protection by cladding in steam generators of waste incinerators (Joerg Metschke); (h) Corrosion protection and wear protection by means of thermal spraying in steam generators (Dietmar Bendix); (i) Review of thick film nickelized components as an effective protection against high-temperature corrosion (Johann-Wilhelm Ansey); (j) Fireproof materials for waste incinerators - characteristics and profile of requirement (Johannes Imle); (k) Service life-relevant aspects of fireproof linings in the thermal recycling of waste (Till Osthoevener and Wolfgang Kollenberg); (l) Alternatives to the fireproof material in the heating space (Heino Sinn); (m) Cladding: Inconal 625 contra 686 - Fundamentals / applications in boiler construction and plant construction (Wolfgang Hoffmeister); (n) Thin films as efficient corrosion barriers - thermal spray coating in waste incinerators and biomass firing (Ruediger W. Schuelein, Steffen Hoehne, Friedrich

  4. Launch Pad Coatings for Smart Corrosion Control

    Science.gov (United States)

    Calle, Luz M.; Hintze, Paul E.; Bucherl, Cori N.; Li, Wenyan; Buhrow, Jerry W.; Curran, Jerome P.; Whitten, Mary C.

    2010-01-01

    Corrosion is the degradation of a material as a result of its interaction with the environment. The environment at the KSC launch pads has been documented by ASM International (formerly American Society for Metals) as the most corrosive in the US. The 70 tons of highly corrosive hydrochloric acid that are generated by the solid rocket boosters during a launch exacerbate the corrosiveness of the environment at the pads. Numerous failures at the pads are caused by the pitting of stainless steels, rebar corrosion, and the degradation of concrete. Corrosion control of launch pad structures relies on the use of coatings selected from the qualified products list (QPL) of the NASA Standard 5008A for Protective Coating of Carbon Steel, Stainless Steel, and Aluminum on Launch Structures, Facilities, and Ground Support Equipment. This standard was developed to establish uniform engineering practices and methods and to ensure the inclusion of essential criteria in the coating of ground support equipment (GSE) and facilities used by or for NASA. This standard is applicable to GSE and facilities that support space vehicle or payload programs or projects and to critical facilities at all NASA locations worldwide. Environmental regulation changes have dramatically reduced the production, handling, use, and availability of conventional protective coatings for application to KSC launch structures and ground support equipment. Current attrition rate of qualified KSC coatings will drastically limit the number of commercial off the shelf (COTS) products available for the Constellation Program (CxP) ground operations (GO). CxP GO identified corrosion detection and control technologies as a critical, initial capability technology need for ground processing of Ares I and Ares V to meet Constellation Architecture Requirements Document (CARD) CxP 70000 operability requirements for reduced ground processing complexity, streamlined integrated testing, and operations phase affordability

  5. A state of the art on primary side stress corrosion cracking in nuclear power plant

    Energy Technology Data Exchange (ETDEWEB)

    Kim, H. P.; Kim, J. S.; Han, J. H.; Lee, D. H.; Lim, Y. S.; Suh, J. H.; Hwang, S. S.; Hur, D. H

    1999-09-01

    A state of art on primary water stress corrosion cracking (PWSCC) of alloy 600 used as steam generator tubing of nuclear power plant and remedial action on the PWSCC were reviewed and analyzed. One of the major metallurgical factors which have effect on PWSCC is Cr carbide distribution. A semicontinuous intergranular Cr carbide distribution enhance PWSCC of alloy 600. PWSCC rate is reported to be reported to be proportional to exp(-50 cal/RT) {sigma}{sup 4}. PWSCC rate also increase with increase in hydrogen partial pressure from 0 to 150 ppm and then decreased with further increase in hydrogen partial pressure to 757 ppm. Development of PWSCC prediction technology which takes into account tubing material, fabrication process and operating history of steam generator is needed to manage PWSCC of domestic nuclear power plant. PWSCC has mainly occurred at expansion irregularities within tubesheet, expansion transitions, dented tube support plate intersections and transition and apex of U bend. Remedial actions to PWSCC are sleeving, plugging, temperature reduction, Ni plating, Ni sleeving, shot peening and steam generator replacement in worst case. Option to remedial actions depend on plant specific such as plant age, leak rate from primary to secondary, density and progression of PWSCC. Ni sleeving developed in Framatome seems to be a powerful method because it never subject to PWSCC. Remedial action should be developed and evaluated for possible PWSCC of domestic nuclear power plant. (author)

  6. Stifling of Crevice Corrosion in Alloy 22

    Energy Technology Data Exchange (ETDEWEB)

    Mon, K G; Gordon, G M; Rebak, R B

    2005-06-08

    Artificially creviced Alloy 22 (N06022) specimens may be susceptible to crevice corrosion in presence of hot chloride containing solutions. The presence of oxyanions in the electrolyte, especially nitrate, may inhibit the nucleation and growth of crevice corrosion. Constant potential tests were performed using tightly creviced specimens of Alloy 22. It was found that crevice corrosion may initiate when a constant potential above the crevice repassivation potential is applied. It was found that as the crevice corrosion nucleated, the current initially increased but later decreased. The net measured current can be converted into penetration following a power law fit of the experimental data. The average power law coefficient ''n'' was found to be 0.439, suggesting that even under constant applied potential crevice corrosion penetration is diffusion controlled.

  7. STIFLING OF CREVICE CORROSION IN ALLOY 22

    Energy Technology Data Exchange (ETDEWEB)

    K.G. Mon; G.M. Gordon; R.B. Rebak

    2005-07-01

    Artificially creviced Alloy 22 (N06022) specimens may be susceptible to crevice corrosion in presence of hot chloride containing solutions. The presence of oxyanions in the electrolyte, especially nitrate, may inhibit the nucleation and growth of crevice corrosion. Constant potential tests were performed using tightly creviced specimens of Alloy 22. It was found that crevice corrosion may initiate when a constant potential above the crevice repassivation potential is applied. It was found that as the crevice corrosion nucleated, the current initially increased but later decreased. The net measured current can be converted into penetration following a power law fit of the experimental data. The average power law coefficient ''n'' was found to be 0.439, suggesting that even under constant applied potential, crevice corrosion penetration is diffusion controlled.

  8. Microencapsulation Technologies for Corrosion Protective Coating Applications

    Science.gov (United States)

    Li, Wenyan; Buhrow, Jerry; Jolley, Scott; Calle, Luz; Pearman, Benjamin; Zhang, Xuejun

    2015-01-01

    Microencapsulation technologies for functional smart Coatings for autonomous corrosion control have been a research area of strong emphasis during the last decade. This work concerns the development of pH sensitive micro-containers (microparticles and microcapsules) for autonomous corrosion control. This paper presents an overview of the state-of-the-art in the field of microencapsulation for corrosion control applications, as well as the technical details of the pH sensitive microcontainer approach, such as selection criteria for corrosion indicators and corrosion inhibitors; the development and optimization of encapsulation methods; function evaluation before and after incorporation of the microcontainers into coatings; and further optimization to improve coating compatibility and performance.

  9. Corrosion of carbon-alloyed iron aluminides

    Indian Academy of Sciences (India)

    M Sen; R Balasubramaniam; A V Ramesh Kumar

    2000-10-01

    The corrosion behaviour of two carbon-alloyed intermetallics of composition Fe–28.1Al–2.1C and Fe–27.5Al–3.7C has been studied and compared with that of binary intermetallics. Potentiodynamic polarization studies indicated that the intermetallics exhibited active–passive behaviour in an acidic solution of pH = 1, whereas they exhibited stable passivity in a buffer solution of pH 8.4. Corrosion rates were also obtained by immersion testing. The variation of corrosion rate as a function of time was similar for both the intermetallics. The variation in corrosion rate as a function of time has been explained based on the observed potentiodynamic polarization behaviour. Scanning electron microscopy of corroded surfaces indicated that the carbon-alloyed intermetallics were susceptible to galvanic corrosion, due to the presence of carbides.

  10. Laser-controllable coatings for corrosion protection.

    Science.gov (United States)

    Skorb, Ekaterina V; Skirtach, Andre G; Sviridov, Dmitry V; Shchukin, Dmitry G; Möhwald, Helmuth

    2009-07-28

    We introduce a novel and versatile approach to the corrosion protection by use of "smart" laser-controllable coating. The main advantage of the proposed technique is that one could terminate the corrosion process by very intensive healing after an appearance of corrosion centers using local laser irradiation. It is also shown that by applying a polyelectrolyte shell with noble metal particles over the mesoporous titania and silica via layer-by-layer assembly it is possible to fabricate micro- and nanoscaled reservoirs, which, being incorporated into the zirconia-organosilica matrix, are responsible for the ability of laser-driven release of the loaded materials (e.g., corrosion inhibitor). Furthermore, the resultant films are highly adhesive and could be easily deposited onto different metallic substrates. Laser-mediated remote release of incorporated corrosion inhibitor (benzotriazole) from engineered mesoporous containers with silver nanoparticles in the container shell is observed in real time on single and multicontainer levels.

  11. Modeling of Corrosion-induced Concrete Damage

    DEFF Research Database (Denmark)

    Thybo, Anna Emilie A.; Michel, Alexander; Stang, Henrik

    2013-01-01

    In the present paper a finite element model is introduced to simulate corrosion-induced damage in concrete. The model takes into account the penetration of corrosion products into the concrete as well as non-uniform formation of corrosion products around the reinforcement. To ac-count for the non......-uniform formation of corrosion products at the concrete/reinforcement interface, a deterministic approach is used. The model gives good estimates of both deformations in the con-crete/reinforcement interface and crack width when compared to experimental data. Further, it is shown that non-uniform deposition...... of corrosion products affects both the time-to cover cracking and the crack width at the concrete surface....

  12. Fuel corrosion processes under waste disposal conditions

    Energy Technology Data Exchange (ETDEWEB)

    Shoesmith, D.W. [Univ. of Western Ontario, Dept. of Chemistry, London, Ontario (Canada)

    1999-09-01

    Under the oxidizing conditions likely to be encountered in the Yucca Mountain Repository, fuel dissolution is a corrosion process involving the coupling of the anodic dissolution of the fuel with the cathodic reduction of oxidants available within the repository. The oxidants potentially available to drive fuel corrosion are environmental oxygen, supplied by the transport through the permeable rock of the mountain and molecular and radical species produced by the radiolysis of available aerated water. The mechanism of these coupled anodic and cathodic reactions is reviewed in detail. While gaps in understanding remain, many kinetic features of these reactions have been studied in considerable detail, and a reasonably justified mechanism for fuel corrosion is available. The corrosion rate is determined primarily by environmental factors rather than the properties of the fuel. Thus, with the exception of increase in rate due to an increase in surface area, pre-oxidation of the fuel has little effect on the corrosion rate.

  13. Passive Corrosion Behavior of Alloy 22

    Energy Technology Data Exchange (ETDEWEB)

    Rebak, R B; Payer, J H

    2006-01-10

    Alloy 22 (N06022) was designed to stand the most aggressive industrial applications, including both reducing and oxidizing acids. Even in the most aggressive environments, if the temperature is lower than 150 F (66 C) Alloy 22 would remain in the passive state having particularly low corrosion rates. In multi-ionic solutions that may simulate the behavior of concentrated ground water, even at near boiling temperatures, the corrosion rate of Alloy 22 is only a few nanometers per year because the alloy is in the complete passive state. The corrosion rate of passive Alloy 22 decreases as the time increases. Immersion corrosion testing also show that the newer generation of Ni-Cr-Mo alloys may offer a better corrosion resistance than Alloy 22 only in some highly aggressive conditions such as in hot acids.

  14. Complete corrosion inhibition through graphene defect passivation.

    Science.gov (United States)

    Hsieh, Ya-Ping; Hofmann, Mario; Chang, Kai-Wen; Jhu, Jian Gang; Li, Yuan-Yao; Chen, Kuang Yao; Yang, Chang Chung; Chang, Wen-Sheng; Chen, Li-Chyong

    2014-01-28

    Graphene is expected to enable superior corrosion protection due to its impermeability and chemical inertness. Previous reports, however, demonstrate limited corrosion inhibition and even corrosion enhancement of graphene on metal surfaces. To enable the reliable and complete passivation, the origin of the low inhibition efficiency of graphene was investigated. Combining electrochemical and morphological characterization techniques, nanometer-sized structural defects in chemical vapor deposition grown graphene were found to be the cause for the limited passivation effect. Extremely fast mass transport on the order of meters per second both across and parallel to graphene layers results in an inhibition efficiency of only ∼50% for Cu covered with up to three graphene layers. Through selective passivation of the defects by atomic layer deposition (ALD) an enhanced corrosion protection of more than 99% was achieved, which compares favorably with commercial corrosion protection methods.

  15. Inhibition of aluminum corrosion using Opuntia extract

    Energy Technology Data Exchange (ETDEWEB)

    El-Etre, A.Y

    2003-11-01

    The inhibitive action of the mucilage extracted from the modified stems of prickly pears, toward acid corrosion of aluminum, is tested using weight loss, thermometry, hydrogen evolution and polarization techniques. It was found that the extract acts as a good corrosion inhibitor for aluminum corrosion in 2.0 M HCl solution. The inhibition action of the extract was discussed in view of Langmuir adsorption isotherm. It was found that the adsorption of the extract on aluminum surface is a spontaneous process. The inhibition efficiency (IE) increases as the extract concentration is increased. The effect of temperature on the IE was studied. It was found that the presence of extract increases the activation energy of the corrosion reaction. Moreover, the thermodynamic parameters of the adsorption process were calculated. It was found also that the Opuntia extract provides a good protection to aluminum against pitting corrosion in chloride ion containing solutions.

  16. Passive Corrosion Behavior of Alloy 22

    Energy Technology Data Exchange (ETDEWEB)

    R.B. Rebak; J.H. Payer

    2006-01-20

    Alloy 22 (NO6022) was designed to stand the most aggressive industrial applications, including both reducing and oxidizing acids. Even in the most aggressive environments, if the temperature is lower than 150 F (66 C) Alloy 22 would remain in the passive state having particularly low corrosion rates. In multi-ionic solutions that may simulate the behavior of concentrated ground water, even at near boiling temperatures, the corrosion rate of Alloy 22 is only a few nano-meters per year because the alloy is in the complete passive state. The corrosion rate of passive Alloy 22 decreases as the time increases. Immersion corrosion testing also show that the newer generation of Ni-Cr-Mo alloys may offer a better corrosion resistance than Alloy 22 only in some highly aggressive conditions such as in hot acids.

  17. Numerical Study of Corrosion Crack Opening

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle; Frandsen, Henrik Lund; Svensson, Staffan

    2008-01-01

    for the corrosion crack opening. Experiments and theoretical analysis by a numerical method, FEM, support that the relation between the reduction of the reinforcement bar diameter due to corrosion and the corresponding increase in crack width for a given time interval, measured on the surface of a concrete specimen...... is proportional. More recently, the constant of proportionality, the so-called crack-corrosion index, has been studied further with respect to its dependence on the diameter of the reinforcement and the concrete cover. In the present paper the above-mentioned work is presented and extended with more realistic 3D......-models of the cracked concrete beam. The crack-corrosion index is evaluated for a variation of different parameters, i.e. bar diameter, concrete cover, crack length and type of corrosion product. This paper is an extended version of a paper by Thoft-Christensen et al. (2005) presented at the IFIP WG 7.5 Conference...

  18. Impacto da perda dentária na qualidade de vida Impact of tooth loss in quality of life

    Directory of Open Access Journals (Sweden)

    Maria Elisa de Souza e Silva

    2010-05-01

    Full Text Available Para avaliar o impacto da perda dentária na qualidade de vida, foram selecionados cinquenta pacientes, usuários do Serviço Público de Saúde, em tratamento para inserção ou substituição do par de dentaduras. Antes do tratamento, aplicou-se o Oral Health Impact Profile (OHIP-14 e a coleta de dados sociodemográficos. Os escores do OHIP-14 foram obtidos por meio do peso de cada pergunta associado à escala de Likert. Maior a pontuação alcançada, maior o impacto negativo da dimensão na qualidade de vida. Na amostra, 82% eram do gênero feminino, 52% tinham 41 a 60 anos (média de 59,1 anos, e 34% eram casados. Para cada dimensão, os valores máximos OHIP-14 foram: desconforto psicológico (122; dor (121; inabilidade psicológica (113; inabilidade física (109; limitação funcional (93; incapacidade (82 e inabilidade social (76. A perda dentária ou o uso de próteses inadequadas implicam impactos negativos na qualidade de vida, especialmente no que se refere à preocupação, estresse decorrente de problemas na boca e à vergonha. Foi percebido menor impacto no que se refere às relações interpessoais e ao desenvolvimento das atividades rotineiras - dimensão inabilidade social. Estas informações são relevantes para os profissionais, pois ampliam seu conhecimento sobre pessoas desdentadas e melhoram sua capacidade de lidar com elas.In order to evaluate the impact of tooth loss in patient's quality of life, 50 volunteers were selected among patients who use the Public Health Services in treatment for their complete denture's placement or replacement. The Oral Health Impact Profile (OHIP-14 and a socio-demographic data collection were applied before treatment. The values were founded through the weight of each question in association with Likert's Scale. As higher was the score, higher was the impact in the quality of life. In this survey 82% were female, 52% of patients between 41 and 60 years old (average: 59.1, and 34% married

  19. Corrosion protection with eco-friendly inhibitors

    Science.gov (United States)

    Shahid, Muhammad

    2011-12-01

    Corrosion occurs as a result of the interaction of a metal with its environment. The extent of corrosion depends on the type of metal, the existing conditions in the environment and the type of aggressive ions present in the medium. For example, CO3-2 and NO-3 produce an insoluble deposit on the surface of iron, resulting in the isolation of metal and consequent decrease of corrosion. On the other hand, halide ions are adsorbed selectively on the metal surface and prevent formation of the oxide phase on the metal surface, resulting in continuous corrosion. Iron, aluminum and their alloys are widely used, both domestically and industrially. Linear alkylbenzene and linear alkylbenzene sulfonate are commonly used as detergents. They have also been found together in waste water. It is claimed that these chemicals act as inhibitors for stainless steel and aluminum. Release of toxic gases as a result of corrosion in pipelines may lead in certain cases to air pollution and possible health hazards. Therefore, there are two ways to look at the relationship between corrosion and pollution: (i) corrosion of metals and alloys due to environmental pollution and (ii) environmental pollution as a result of corrosion protection. This paper encompasses the two scenarios and possible remedies for various cases, using 'green' inhibitors obtained either from plant extracts or from pharmaceutical compounds. In the present study, the effect of piperacillin sodium as a corrosion inhibitor for mild steel was investigated using a weight-loss method as well as a three-electrode dc electrochemical technique. It was found that the corrosion rate decreased as the concentration of the inhibitor increased up to 9×10-4 M 93% efficiency was exhibited at this concentration.

  20. 25-year analysis of a dental undergraduate research training program (BSc Dent) at the University of Manitoba Faculty of Dentistry.

    Science.gov (United States)

    Scott, J E; de Vries, J; Iacopino, A M

    2008-12-01

    Research in the context of the dental school has traditionally been focused on institutional/faculty accomplishments and generating new knowledge to benefit the profession. Only recently have significant efforts been made to expand the overall research programming into the formal dental curriculum, to provide students with a baseline exposure to the research and critical thinking processes, encourage evidence-based decision-making, and stimulate interest in academic/research careers. Various approaches to curriculum reform and the establishment of multiple levels of student research opportunities are now part of the educational fabric of many dental schools worldwide. Many of the preliminary reports regarding the success and vitality of these programs have used outcomes measures and metrics that emphasize cultural changes within institutions, student research productivity, and student career preferences after graduation. However, there have not been any reports from long-standing programs (a minimum of 25 years of cumulative data) that describe dental school graduates who have had the benefit of research/training experiences during their dental education. The University of Manitoba Faculty of Dentistry initiated a BSc Dent program in 1980 that awarded a formal degree for significant research experiences taking place within the laboratories of the Faculty-based researchers and has continued to develop and expand this program. The success of the program has been demonstrated by the continued and increasing demands for entry, the academic achievements of the graduates, and the numbers of graduates who have completed advanced education/training programs or returned to the Faculty as instructors. Analysis of our long-term data validates many recent hypotheses and short-term observations regarding the benefits of dental student research programs. This information may be useful in the design and implementation of dental student research programs at other dental schools.

  1. Microbial corrosion of aluminum alloy.

    Science.gov (United States)

    Yang, S S; Chen, C Y; Wei, C B; Lin, Y T

    1996-11-01

    Several microbes were isolated from the contaminated fuel-oil in Taiwan and the microbial corrosion of aluminum alloy A356-T6 was tested by MIL-STD-810E test method. Penicillium sp. AM-F5 and Cladosporium resinac ATCC 22712 had significant adsorption and pitting on the surface of aluminum alloy, Pseudomonas acruginosa AM-B5 had weak adsorption and some precipitation in the bottom, and Candida sp. AM-Y1 had the less adsorption and few cavities formation on the surface. pH of the aqueous phase decreased 0.3 to 0.7 unit for 4 months of incubation. The corrosion of aluminum alloy was very significant in the cultures of Penicillium sp. AM-F2, Penicillium sp. AM-F5 and C. resinac ATCC 22712. The major metabolites in the aqueous phase with the inoculation of C. resinac were citric acid and oxalic acid, while succinic acid and fumaric acid were the minors.

  2. Migrating corrosion inhibitor blend for reinforced concrete: Part 1 -- Prevention of corrosion

    Energy Technology Data Exchange (ETDEWEB)

    Elsener, B.; Buechler, M.; Stalder, F.; Boehni, H.

    1999-12-01

    The efficiency of a migrating corrosion inhibitor in preventing corrosion of mild steel was investigated in saturated calcium hydroxide (Ca[OH]{sub 2}) solutions and in mortar. The protective effect of the inhibitor against pitting corrosion caused by chloride attack and against uniform corrosion as a result of carbonation was determined. Results showed that high concentrations ({approx}10%) allowed the inhibition of pitting corrosion tritiation in solution containing 1 M/L sodium chloride (NaCl). However, inhibiting properties can be lost by evaporation of the volatile constituent of the inhibitor or by the precipitation of the nonvolatile fraction of the inhibitor in presence of calcium ions. Addition of the inhibitor blend to mortar yielded a retardation of the corrosion initiation in the case of chloride-induced corrosion, but o significant reduction in corrosion rate. No effect was found in carbonated samples, and no influence on the corrosion rate was detected. Additionally, the estimation of the extent of the retarding effect on corrosion initiation on real structures was difficult, as the inhibitor was found to evaporate from the mortar. This evaporation resulted in a loss of inhibiting properties. Hence, the long-term efficiency of the inhibitor could not be guaranteed.

  3. Evaluation of fracture resistance of endodontically treated teeth restored with prefabricated posts and composites with varying quantities of remaining coronal tooth structure Avaliação da resistência à fratura de dentes tratados endodonticamente restaurados com pinos pré-fabricados e resinas compostas variando o remanescente dentário coronal

    Directory of Open Access Journals (Sweden)

    Murilo Pereira de Melo

    2005-06-01

    Full Text Available OBJECTIVES: The aim of this study was to evaluate the influence of remaining coronal tooth structure on endodontically treated teeth restored with prefabricated posts and two different composites for core build-up: dual-cured resin (Enforce Core and light-cured resin (Z-250. METHODS: Fourty freshly extracted canines were endodontically treated and divided into four groups: Group I - teeth with 3mm remaining coronal structure, restored with Enforce Core; Group II - teeth with 3mm remaining coronal structure, restored with Z-250; Group III - teeth with no remaining coronal structure, restored with Enforce; Group IV - teeth with no remaining coronal structure, restored with Z-250. After restoration, the teeth were embedded in acrylic resin and the fracture resistance was measured on a universal testing machine at 45 degrees to the long axis of the tooth until failure. RESULTS: Data were analyzed by two-way analysis of variance, which showed significant differences between groups (p=0.00. The Tukey test did not show significant differences between specimens with and without remaining coronal structure. Conversely, significant difference was observed between groups with different core build-up. The highest values of fracture resistance were found in the group restored with light-cured resin. SIGNIFICANCE: The remaining coronal tooth structure did not influence the resistance of endodontically treated teeth; however, the change of core build-up was able to modify this resistence.O objetivo desta pesquisa foi avaliar a influência do remanescente dentário coronal de dentes tratados endodonticamente, restaurados com pinos pré-fabricados e duas resinas como núcleos de preenchimento, uma de presa dual (Enforce Core e outra fotopolimerizável (Z-250. Foram utilizados 40 caninos superiores humanos extraídos, divididos em quatro grupos de 10 espécimes: Grupo l - com remanescente dentário coronal de 3mm e restaurados com Enforce Core; Grupo ll - com

  4. 基于有限元仿真的喷丸工艺参数对冲击坑形状和尺寸的影响%Impaction of Shot Peening Process Parameters to Dent Shape and Dent Size by Dynamic Finite Element Analysis

    Institute of Scientific and Technical Information of China (English)

    陈星; 鲁世红; 高国强

    2013-01-01

    喷丸工艺是一种有效提高工件疲劳寿命和改善工件表面完整性的表面处理方法,被广泛应用于航空、航天、船舶、汽车等军民用领域.研究表明,弹丸冲击金属材料表面形成的冲击坑形状和尺寸与工件表面完整性有重要的对应关系,表面完整性是影响结构零部件工作质量、寿命和可靠性的重要因素.本文应用有限元分析的方法系统地研究了喷丸处理过程中的一些关键参数对形成的冲击坑形状和尺寸的影响,结果显示,弹丸速度、直径、材料、重复冲击次数对冲击坑的尺寸影响显著,同时,弹丸的屈服应力对冲击坑的形状影响显著,而弹丸与靶材之间的摩擦系数对冲击坑的形状和尺寸影响都较小.冲击坑直径比的饱和值为2.5,冲击坑深度比的饱和值为0.2.将冲击坑模拟结果与Nobuyuki等人用ANSYS软件所模拟的结果进行对比,结果吻合得较好.本文有限元模拟的结果,可用于对生产实际中喷丸工艺参数的优化,对新机研制中的飞机壁板等零件的喷丸成形工艺制定具有重要的指导意义.%Shot peening is an effective surface treatment technology to significantly improve fatigue life and surface integrality of the peened part and it is widely used in aerospace industry, ship building, car manufacture and other areas. Dent shape and size produced by single shot impacting on surfaces of a metallic component are closely related with surface integrity according the research. Surface integrity is an important factor which will affect the quality, performance, life and reliability of the parts and components. The variation of the dent shape and dent size versus shot parameter was systematically researched by proposing a finite element model for shot peening. Results show that velocity, diameter, material and repeating times of a shot all play important roles on the dent shape and size; the yield stress of the shot obviously affect the dent

  5. Atmospheric Corrosivity at Australian and Overseas Airbases and Airports

    Science.gov (United States)

    2014-07-01

    protective coating systems and corrosion inhibitor treatments deteriorate and become less effective. The CLIMAT environmental corrosion test has...UNCLASSIFIED UNCLASSIFIED Atmospheric Corrosivity at Australian and Overseas Airbases and Airports J C Bitcon Maritime...Division Defence Science and Technology Organisation DSTO-TN-1320 ABSTRACT Atmospheric corrosivity at 25 airbases and airports in Australia

  6. 49 CFR 193.2631 - Internal corrosion control.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Internal corrosion control. 193.2631 Section 193... GAS FACILITIES: FEDERAL SAFETY STANDARDS Maintenance § 193.2631 Internal corrosion control. Each component that is subject to internal corrosive attack must be protected from internal corrosion by—...

  7. 49 CFR 192.475 - Internal corrosion control: General.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Internal corrosion control: General. 192.475... Control § 192.475 Internal corrosion control: General. (a) Corrosive gas may not be transported by... taken to minimize internal corrosion. (b) Whenever any pipe is removed from a pipeline for any...

  8. 46 CFR 154.412 - Cargo tank corrosion allowance.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Cargo tank corrosion allowance. 154.412 Section 154.412... Containment Systems § 154.412 Cargo tank corrosion allowance. A cargo tank must be designed with a corrosion...) carries a cargo that corrodes the tank material. Note: Corrosion allowance for independent tank type C...

  9. 49 CFR 193.2627 - Atmospheric corrosion control.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Atmospheric corrosion control. 193.2627 Section... LIQUEFIED NATURAL GAS FACILITIES: FEDERAL SAFETY STANDARDS Maintenance § 193.2627 Atmospheric corrosion... atmospheric corrosion by— (a) Material that has been designed and selected to resist the corrosive...

  10. Corrosion damage evolution and residual strength of corroded aluminum alloys

    Institute of Scientific and Technical Information of China (English)

    Youhong Zhang; Guozhi Lv; Hui Wang; Bomei Si; Yueliang Cheng

    2008-01-01

    The LY12CZ aluminum alloy specimens were eurroded under the conditions of different test temperatures and exposure durations. After corrosion exposure, fatigue tests were performed. Scanning electron microscopy and optical microscope analyses on corrosion damage were carried out. The definition of surface corrosion damage ratio was provided to describe the extent of surface corrosion damage. On the basis of the measured data sets of the corrosion damage ratio, the probabilistic model of corrosion damage evolution was built. The corrosion damage decreased the fatigue life by a factor of about 1.25 to 2.38 and the prediction method of residual strength of the corroded structure was presented.

  11. A Calculation Model for Corrosion Cracking in RC Structures

    Institute of Scientific and Technical Information of China (English)

    Xu Gang; Wei Jun; Zhang Keqiang; Zhou Xiwu

    2007-01-01

    A novel calculation model is proposed aiming at the problem of concrete cover cracking induced by reinforcement corrosion. In this article, the relationship between the corrosion depth of the bar and the thickness of the rust layer is established. By deducing the radial displacement expression of concrete, the formula for corrosion depth and corrosion pressure before cracking is proposed. The crack depth of cover in accordance with the maximum corrosion pressure is deduced; furthermore, the corrosion depth and corrosion pressure at the cracking time are obtained. Finally, the theoretical model is validated by several experiments, and the calculated values agree well with the experiment results.

  12. Corrosion inhibitors for intermediate cooling systems

    Energy Technology Data Exchange (ETDEWEB)

    Falk, I.; Suhr, L.

    1985-04-01

    The selected inhibitors were tested for heat and radiation stability and corrosion protection on the bench scale. Based on the results from these tests two of the products were selected, Bycoguard 81 and Bycoguard MP4S for continuing corrosion tests in an autoclave loop at 90 degrees C and 120 degrees C. Oxygen saturated deionized water with an addition of 1 ppm chloride was recirculated in the loop. Samples of copper and carbon steel were exposed to the water in the autoclave for periods up to 10 weeks. The purpose of this project was to find a substitute for hydrazine and chromates. Besides good corrosion protection qualities the toxic and environmental effect of the inhibitors should be minimal. The investigation has shown that the copper inhibitor BTA (benzotriazole) loses its corrosion protection qualities at a water temperature of 120 degrees C. The protection effects at 90 degrees C were satisfactory for both of the materials. The corrosion rates measured were 0.01 mm/y or less for the copper and carbon steel samples. The environment in the autoclave during the testing was more corrosive than is to be found in intermediate cooling systems. Due to the low corrosion rates measured the two inhibitors are to be recommended as alternatives to hydrazine and chromates.

  13. Mesoporous silica nanoparticles for active corrosion protection.

    Science.gov (United States)

    Borisova, Dimitriya; Möhwald, Helmuth; Shchukin, Dmitry G

    2011-03-22

    This work presents the synthesis of monodisperse, mesoporous silica nanoparticles and their application as nanocontainers loaded with corrosion inhibitor (1H-benzotriazole (BTA)) and embedded in hybrid SiOx/ZrOx sol-gel coating for the corrosion protection of aluminum alloy. The developed porous system of mechanically stable silica nanoparticles exhibits high surface area (∼1000 m2·g(-1)), narrow pore size distribution (d∼3 nm), and large pore volume (∼1 mL·g(-1)). As a result, a sufficiently high uptake and storage of the corrosion inhibitor in the mesoporous nanocontainers was achieved. The successful embedding and homogeneous distribution of the BTA-loaded monodisperse silica nanocontainers in the passive anticorrosive SiOx/ZrOx film improve the wet corrosion resistance of the aluminum alloy AA2024 in 0.1 M sodium chloride solution. The enhanced corrosion protection of this newly developed active system in comparison to the passive sol-gel coating was observed during a simulated corrosion process by the scanning vibrating electrode technique (SVET). These results, as well as the controlled pH-dependent release of BTA from the mesoporous silica nanocontainers without additional polyelectrolyte shell, suggest an inhibitor release triggered by the corrosion process leading to a self-healing effect.

  14. Marine atmospheric corrosion of carbon steels

    Energy Technology Data Exchange (ETDEWEB)

    Morcillo, M.; Alcantara, J.; Diaz, I.; Chico, B.; Simancas, J.; Fuente, D. de la

    2015-07-01

    Basic research on marine atmospheric corrosion of carbon steels is a relatively young scientific field and there continue to be great gaps in this area of knowledge. The presence of akaganeite in the corrosion products that form on steel when it is exposed to marine atmospheres leads to a notable increase in the corrosion rate. This work addresses the following issues: (a) environmental conditions necessary for akaganeite formation; (b) characterisation of akaganeite in the corrosion products formed; (c) corrosion mechanisms of carbon steel in marine atmospheres; (d) exfoliation of rust layers formed in highly aggressive marine atmospheres; (e) long-term corrosion rate prediction; and (f) behaviour of weathering steels. Field research has been carried out at Cabo Vilano wind farm (Camarinas, Galicia) in a wide range of atmospheric salinities and laboratory work involving the use of conventional atmospheric corrosion techniques and near-surface and bulk sensitive analytical techniques: scanning electron microscopy (SEM)/energy dispersive spectrometry (EDS), X-ray diffraction (XRD), Mossbauer spectroscopy and SEM/μRaman spectroscopy. (Author)

  15. Recent Natural Corrosion Inhibitors for Mild Steel: An Overview

    Directory of Open Access Journals (Sweden)

    Marko Chigondo

    2016-01-01

    Full Text Available Traditionally, reduction of corrosion has been managed by various methods including cathodic protection, process control, reduction of the metal impurity content, and application of surface treatment techniques, as well as incorporation of suitable alloys. However, the use of corrosion inhibitors has proven to be the easiest and cheapest method for corrosion protection and prevention in acidic media. These inhibitors slow down the corrosion rate and thus prevent monetary losses due to metallic corrosion on industrial vessels, equipment, or surfaces. Inorganic and organic inhibitors are toxic and costly and thus recent focus has been turned to develop environmentally benign methods for corrosion retardation. Many researchers have recently focused on corrosion prevention methods using green inhibitors for mild steel in acidic solutions to mimic industrial processes. This paper provides an overview of types of corrosion, corrosion process, and mainly recent work done on the application of natural plant extracts as corrosion inhibitors for mild steel.

  16. Novel Corrosion Sensor for Vision 21 Systems

    Energy Technology Data Exchange (ETDEWEB)

    Heng Ban

    2005-12-01

    Advanced sensor technology is identified as a key component for advanced power systems for future energy plants that would have virtually no environmental impact. This project intends to develop a novel high temperature corrosion sensor and subsequent measurement system for advanced power systems. Fireside corrosion is the metal loss caused by chemical reactions on surfaces exposed to the combustion environment. Such corrosion is the leading mechanism for boiler tube failures and has emerged to be a significant concern for current and future energy plants due to the introduction of technologies targeting emissions reduction, efficiency improvement, or fuel/oxidant flexibility. Corrosion damage can lead to catastrophic equipment failure, explosions, and forced outages. Proper management of corrosion requires real-time indication of corrosion rate. However, short-term, on-line corrosion monitoring systems for fireside corrosion remain a technical challenge to date due to the extremely harsh combustion environment. The overall objective of this project is to develop a technology for on-line corrosion monitoring based on a new concept. This objective is to be achieved by a laboratory development of the sensor and instrumentation, testing of the measurement system in a laboratory muffle furnace, and eventually testing the system in a coal-fired furnace. The initial plan for testing at the coal-fired pilot-scale furnace was replaced by testing in a power plant, because the operation condition at the power plant is continuous and more stable. The first two-year effort was completed with the successful development sensor and measurement system, and successful testing in a muffle furnace. Because of the potential high cost in sensor fabrication, a different type of sensor was used and tested in a power plant burning eastern bituminous coals. This report summarize the experiences and results of the first two years of the three-year project, which include laboratory

  17. Slurry Chemical Corrosion and Galvanic Corrosion during Copper Chemical Mechanical Polishing

    Science.gov (United States)

    Kondo, Seiichi; Sakuma, Noriyuki; Homma, Yoshio; Ohashi, Naofumi

    2000-11-01

    Copper (Cu) corrosion during chemical mechanical polishing (CMP) was controlled in order to improve the Cu damascene interconnect process. Slurry chemical corrosion was found to be enhanced when the slurry was diluted by deionized (DI) water during rinsing just after CMP@. Since the corrosion inhibitor, benzotriazole (BTA), reduces the Cu removal rate, adding it to the rinse solution prevents chemical corrosion more effectively than adding it to the slurry. On the other hand, galvanic corrosion occurs at the interface between Cu and the barrier metal, and it can be prevented by selecting appropriate barrier metals. Because the difference between the electrochemical potentials of Cu and the barrier metal is small in the slurry, refractory metals such as Ta, TaN, and TiN were found to be appropriate barrier metals. On the other hand, W, WN, and Ti have large potential differences, so galvanic corrosion was clearly observed when Cu/W damascene interconnects were fabricated.

  18. A STUDY OF CORROSION AND STRESS CORROSION CRACKING OF CARBON STEEL NUCLEAR WASTE STORAGE TANKS

    Energy Technology Data Exchange (ETDEWEB)

    BOOMER, K.D.

    2007-08-21

    The Hanford reservation Tank Farms in Washington State has 177 underground storage tanks that contain approximately 50 million gallons of liquid legacy radioactive waste from cold war plutonium production. These tanks will continue to store waste until it is treated and disposed. These nuclear wastes were converted to highly alkaline pH wastes to protect the carbon steel storage tanks from corrosion. However, the carbon steel is still susceptible to localized corrosion and stress corrosion cracking. The waste chemistry varies from tank to tank, and contains various combinations of hydroxide, nitrate, nitrite, chloride, carbonate, aluminate and other species. The effect of each of these species and any synergistic effects on localized corrosion and stress corrosion cracking of carbon steel have been investigated with electrochemical polarization, slow strain rate, and crack growth rate testing. The effect of solution chemistry, pH, temperature and applied potential are all considered and their role in the corrosion behavior will be discussed.

  19. Waste of cleaning emulsion sewage as inhibitors of steel corrosion

    Science.gov (United States)

    Fazullin, D. D.; Mavrin, G. V.; Shaikhiev, I. G.

    2016-06-01

    The article describes the corrosion test of steel of the brand 20 in the stratal water. To increase corrosion resistance as a corrosion inhibitor the concentrate waste emulsion of the mark "Incam- 1" was provided. The article presents studies of the corrosion rate with different dosages of corrosion inhibitor in the stratal water. Based on these research results are revealed that the degree of protection of steel is 27% at a dosage of 3.8 g / dm3.

  20. Assessment of Commercial Corrosion Inhibiting Admixtures for Reinforced Concrete

    OpenAIRE

    Brown, Michael Carey

    1999-01-01

    Corrosion of reinforcing steel in concrete exposed to chloride-laden environments is a well-known and documented phenomenon. The need for cost effective systems for protection against corrosion has become increasingly clear since the first observations of severe corrosion damage to interstate bridges in the 1960's. As one potential solution to the mounting problem of corrosion deterioration of structures, corrosion-inhibiting admixtures have been researched and introduced into service. ...

  1. A Localised Corrosion Cell for Industrial Applications

    DEFF Research Database (Denmark)

    Andersen, A.; Hilbert, Lisbeth Rischel; Jansen, P.

    2003-01-01

    The LOCORR-CELL™ developed by FORCE TECHNOLOGY is an electrochemical cell for industrial applications estimating localised corrosion. The cell is constructed in a carbon steel casing for direct mounting into the system. It is based on an oxygen concentration element reflecting the interaction...... between the environment formed under a deposit or in a crevice. The essential feature of the method is that it reflects the influence of oxygen content, conductivity and temperature as well as the influence of corrosion inhibitors, MIC and other effects that have an effect on localised corrosion under...

  2. Numerical Modeling of Weld Joint Corrosion

    Science.gov (United States)

    Lu, Yongxin; Jing, Hongyang; Han, Yongdian; Xu, Lianyong

    2016-03-01

    A numerical model is presented in this work that predicts the corrosion rate of weld joint. The model is able to track moving boundary of the corroding constituent of weld joint. The corrosion rates obtained from the model are compared with those estimated from mixed potential theory and two experimental techniques, namely immersion test and constant potential polarization test. The corrosion rate predicted using the model is within 10% of the estimate from the mixed potential theory, within 20% of that got from the immersion experiment and within 10% of that got from the constant potential polarization experiment for weld joint.

  3. Numerical modelling of corrosion - Theoretical backgrounds -

    Energy Technology Data Exchange (ETDEWEB)

    Warkus, J.; Raupach, M. [ibac, RWTH Aachen (Germany); Gulikers, J. [Ministry of Transport, Rijkswaterstaat, Bouwdienst, Utrecht (Netherlands)

    2006-08-15

    During recent years research projects with different approaches have been carried out to develop models which are suitable to assess the metal removal rate in case of reinforcement corrosion. Some of them are based on empirical methods and correlate the corrosion rate to parameters like concrete resistivity, temperature and relative humidity. Another type of model is based on a quantification of the ongoing electrochemical processes. In this paper the theoretical backgrounds and mathematical descriptions of reinforcement corrosion with regard to a numerical modelling are presented and discussed. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  4. Corrosion resistant storage container for radioactive material

    Science.gov (United States)

    Schweitzer, Donald G.; Davis, Mary S.

    1990-01-01

    A corrosion resistant long-term storage container for isolating radioactive waste material in a repository. The container is formed of a plurality of sealed corrosion resistant canisters of different relative sizes, with the smaller canisters housed within the larger canisters, and with spacer means disposed between judxtaposed pairs of canisters to maintain a predetermined spacing between each of the canisters. The combination of the plural surfaces of the canisters and the associated spacer means is effective to make the container capable of resisting corrosion, and thereby of preventing waste material from leaking from the innermost canister into the ambient atmosphere.

  5. A Localised Corrosion Cell for Industrial Applications

    DEFF Research Database (Denmark)

    Andersen, A.; Hilbert, Lisbeth Rischel; Jansen, P.

    2003-01-01

    The LOCORR-CELL™ developed by FORCE TECHNOLOGY is an electrochemical cell for industrial applications estimating localised corrosion. The cell is constructed in a carbon steel casing for direct mounting into the system. It is based on an oxygen concentration element reflecting the interaction...... between the environment formed under a deposit or in a crevice. The essential feature of the method is that it reflects the influence of oxygen content, conductivity and temperature as well as the influence of corrosion inhibitors, MIC and other effects that have an effect on localised corrosion under...

  6. The corrosion and corrosion mechanical properties evaluation for the LBB concept in VVERs

    Energy Technology Data Exchange (ETDEWEB)

    Ruscak, M.; Chvatal, P.; Karnik, D.

    1997-04-01

    One of the conditions required for Leak Before Break application is the verification that the influence of corrosion environment on the material of the component can be neglected. Both the general corrosion and/or the initiation and, growth of corrosion-mechanical cracks must not cause the degradation. The primary piping in the VVER nuclear power plant is made from austenitic steels (VVER 440) and low alloy steels protected with the austenitic cladding (VVER 1000). Inspection of the base metal and heterogeneous weldments from the VVER 440 showed that the crack growth rates are below 10 m/s if a low oxygen level is kept in the primary environment. No intergranular cracking was observed in low and high oxygen water after any type of testing, with constant or periodic loading. In the framework of the LBB assessment of the VVER 1000, the corrosion and corrosion mechanical properties were also evaluated. The corrosion and corrosion mechanical testing was oriented predominantly to three types of tests: stress corrosion cracking tests corrosion fatigue tests evaluation of the resistance against corrosion damage. In this paper, the methods used for these tests are described and the materials are compared from the point of view of response on static and periodic mechanical stress on the low alloyed steel 10GN2WA and weld metal exposed in the primary circuit environment. The slow strain rate tests and static loading of both C-rings and CT specimens were performed in order to assess the stress corrosion cracking characteristics. Cyclic loading of CT specimens was done to evaluate the kinetics of the crack growth under periodical loading. Results are shown to illustrate the approaches used. The data obtained were evaluated also from the point of view of comparison of the influence of different structure on the stress corrosion cracking appearance. The results obtained for the base metal and weld metal of the piping are presented here.

  7. Corrosion Effects on the Strength Properties of Steel Fibre Reinforced Concrete Containing Slag and Corrosion Inhibitor

    OpenAIRE

    Sivakumar Anandan; Sounthararajan Vallarasu Manoharan; Thirumurugan Sengottian

    2014-01-01

    Corrosion in steel can be detrimental in any steel rebar reinforced concrete as well as in the case of steel fibre reinforced concrete. The process of corrosion occurring in steel fibre incorporated concrete subjected to corrosive environment was systematically evaluated in this study. Concrete specimens were prepared with steel fibre inclusions at 1.5% Vf (volume fraction) of concrete and were added in slag based concrete (containing manufactured sand) and replaced with cement at 20%, 40%, ...

  8. Development of Copper Corrosion Products and Relation between Surface Appearance and Corrosion Rate

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Tran Thi Ngoc; Binh, Nguyen Thi Thanh [Vietnam National University, Ho Chi Minh (Viet Nam); Tru, Nguyen Nhi [Vietnam Institute for Tropical Technology and Environmental Protection, Ho Chi Minh (Viet Nam); Yoshino, Tsujino [Osaka Prefecture, Osaka (Japan); Yasuki, Maeda [Osaka Prefecture University, Osaka (Japan)

    2008-04-15

    Copper was exposed unsheltered and sheltered in four humid tropical sites, representing urban, urban-industrial, urban-marine and rural environments. The corrosion rates and the sequence of corrosion product formation are presented and discussed in relation with climatic and atmospheric pollution parameters. Chemical compositions of corrosion products were found to depend on environments and duration of exposure. In all environments, cuprite was the predominating corrosion product that formed first and continuously increased during the exposure. Among the sulphur-containing corrosion products, posnjakite and brochantite were more frequently found and the first formed earlier. Nantokite was the most common chlorine-containing products for most cases, except the high-chloride environment, where atacamite was detected instead. The corrosion rate of copper was well indicated by the colour of patina. The red-purple colour corresponded to the high corrosion rate and the greenish grey colour corresponded to the low corrosion rate. Corrosion rate of sheltered copper in urban-marine environment increased with the exposure time.

  9. Electrochemical corrosion behavior of steel wires in a coalmine with a corrosive medium

    Institute of Scientific and Technical Information of China (English)

    Wang Songquan; Zhang Dekun; Wang Dagang; Zhang Zefeng

    2011-01-01

    A 6 × 19 point-contact hoisting cable was used as our research object to examine the progress of corrosion of steel wires in a laboratory, simulating the actual working conditions in a coalmine. An electrochemical method was used to investigate the corrosion behavior of steel wires with different surface treatments of a corrosive acid solution. The results show that anode activation of steel wire mainly occurs during pre-corrosion, where the anode activation process of bare steel wires is the fastest as is their corresponding corrosion speed, while the anode activation process of oil coated steel wires and their corresponding corrosion speed are the lowest. During the intermediate and late immersion periods,a passive film is generated on the surface of steel wires, which are gradually damaged with the passage of time. Local pitting corrosion occurs easily on the surface of steel wires with a high-polarization potential.Suitable equivalent circuits were chosen to fit the electrochemical impedance spectroscopy (EIS) of steel wires over various corrosive times and different surface treatments, which indicate good fitting results.The double electrical layer charge-transfer resistance increases in the sequence: bare steel wire,untreated steel wire and oil coated steel wire and their corrosion resistance decreases in turn, which is consistent with their polarization curves. The oil layer provides a certain protective effect on untreated steel wires, but its effect is not entirely clear.

  10. Meios de conservação do dente avulsionado: revisão da literatura = Storage media for avulsed teeth: review of literature

    Directory of Open Access Journals (Sweden)

    Borba, Maristela Gutiérrez de

    2014-01-01

    Full Text Available A avulsão é um traumatismo dentário de graves consequências para o dente permanente pelo dano que pode ocorrer à estrutura periodontal. O reimplante imediato deve ser o tratamento de eleição, porém muitas vezes não é possível, e o sucesso do futuro reimplante dependerá do tempo em que o dente permanece fora do alvéolo e o meio no qual ele é mantido. O objetivo deste trabalho é fazer uma revisão da literatura sobre os meios de conservação devido a sua importância no prognóstico do reimplante. Embora muitos meios venham sendo testados, até o momento nenhum deles preenche todos os requisitos biológicos e ainda esteja disponível no local do acidente. A saliva e a água, embora sejam de fácil acesso, têm demonstrado causar efeitos deletérios nas células do ligamento periodontal. Apesar dos seus efeitos biológicos positivos, os meios de cultura raramente estão ascessíveis no local do acidente, o que torna seu uso impraticável. A própolis e o extrato de chá verde parecem ser promissores e novos estudos ainda precisam ser realizados. O leite, em especial o longa vida desnatado, parece ser uma boa opção, pois apresenta bons resultados com relação à viabilidade celular e costuma estar disponível

  11. Má oclusão Classe II, 2ª divisão de Angle, tratada com exodontias de dentes permanentes

    OpenAIRE

    Dalagnol,Sílvio Luís

    2011-01-01

    Este artigo relata o tratamento ortodôntico de uma paciente do sexo feminino, adulta, portadora de uma má oclusão Classe II, 2ª divisão de Angle, com terceiros molares superiores inclusos, bolsa periodontal, recessões gengivais e desgastes dentários. A paciente foi tratada com exodontia dos segundos pré-molares superiores e controle de ancoragem. Este caso foi apresentado à Diretoria do Board Brasileiro de Ortodontia e Ortopedia Facial (BBO), representando a categoria Livre Escolha, como part...

  12. Avaliação do perfil de risco de cárie dentária em gestantes de Araraquara, Brasil

    Directory of Open Access Journals (Sweden)

    Tatiana Carolina De Aguiar

    2011-12-01

    Full Text Available O conhecimento do risco de cárie na gravidez é essencial para um correto plano de tratamento com ações educativas e preventivas às mães para que possam cuidar adequadamente de sua saúde bucal e de seus filhos. Este estudo retrospectivo teve como objetivo identificar o risco de cárie de gestantes (15-44 anos; média= 25 anos que frequentaram a clínica de odontologia preventiva da Faculdade de Odontologia de Araraquara, Universidade Estadual Paulista de 1999 a 2007. Um total de 166 prontuários, preenchidos por alunos do 3º ano do Curso de Graduação, seguindo orientações pré-estabelecidas, foram utilizados. Coletou-se informação sobre: classificação do diagnóstico de risco de cárie, trimestre gestacional, consumo de carboidratos (entre ou durante as refeições, placa corada (registro de controle de placa de O'Leary, número e grupo de dentes com experiência de cárie. Para análise estatística foram utilizados o teste de qui-quadrado e ANOVA. A maioria das gestantes (92,1 % apresentou 25 % ou mais das superfícies dentárias com placa dental. A média (desvio-padrão de dentes obturados e cariados foi 7,9 (5,1 e 4,0 (3,4, respectiva emente. Os dentes posteriores foram os mais acometidos por cárie/restaurações. Quanto ao diagnóstico de risco à cárie, a classificação alta foi observada em 38,5 % das gestantes, moderada em 47,6 % e baixa em 13,9 %. Houve associação estatisticamente significativa (p= 0,001 entre o consumo de carboidratos e o diagnóstico de risco de cárie. O índice de placa foi semelhante nos diferentes trimestres gestacionais (f= 0,223; p= 0,803. Portanto pode-se concluir que o risco de cárie da grande maioria das gestantes foi alto ou moderado e esteve estatisticamente associado ao consumo de carboidratos.

  13. Avaliação da variação de pH e da permeabilidade da dentina cervical em dentes submetidos ao tratamento clareador

    Directory of Open Access Journals (Sweden)

    Dezotti Mariela S. G.

    2002-01-01

    Full Text Available A reabsorção cervical externa da raiz é uma das desvantagens do procedimento clareador. Vários são os mecanismos que podem ser responsáveis por desencadear esta reabsorção, dentre eles, a ação química e física dos materiais utilizados, bem como a morfologia da junção amelocementária. Este trabalho teve como objetivo observar uma possível via de comunicação entre a câmara pulpar e a superfície externa da raiz, medindo o pH e a infiltração de corante na dentina cervical após o procedimento clareador. Realizou-se o tratamento endodôntico em 34 dentes incisivos permanentes. Os dentes foram divididos em 3 grupos experimentais de acordo com o nível do corte da obturação e selamento da embocadura dos canais com cimento de ionômero de vidro. O clareamento foi realizado usando perborato de sódio e peróxido de hidrogênio a 30%. As leituras do pH foram realizadas após 30 min, 24 h, 48 h e 72 h do início do procedimento. A seguir, os dentes foram imersos em fucsina básica a 0,5% por 24 h para determinarmos possíveis diferenças na permeabilidade da dentina cervical. Os resultados mostraram que o pH apresentou tendência a se modificar quando o corte da obturação permaneceu na embocadura dos canais, bem como quando se removeram 2 mm da obturação e quando se selou a embocadura com cimento de ionômero de vidro. A permeabilidade dentinária aumentou nos 3 grupos experimentais, em comparação com os dentes que compreenderam o grupo controle. Estas leves diferenças podem sugerir uma via de comunicação entre a câmara pulpar e a superfície externa da raiz.

  14. Tratamento de superfície de porcelanas dentárias pela irradiação com laser de CO2

    OpenAIRE

    2013-01-01

    Este estudo teve como objetivo testar o laser de CO2 como um agente de tratamento de superfície de porcelanas dentárias. Material e Métodos: O estudo foi dividido em duas etapas: na primeira etapa, discos de porcelana (3,5 mm diam. x 2,0 mm espess.) das marcas VM7, VM9 e VM13 (VITA) foram sinterizados e tiveram uma de suas faces asperizadas por uma ponta diamantada 2134F para acabamento. Os espécimes foram então divididos em grupos de acordo com os seguintes tratamentos: nenhum (C), auto-glaz...

  15. Implante de células-tronco de polpa dentária humana associadas à biomateriais para o reparo de lesões em joelhos de ovinos

    OpenAIRE

    Marcos Vinícius Mendes Silva

    2011-01-01

    A terapia celular com células-tronco (CT) surgiu nos últimos anos como uma esperança para o tratamento de doenças, sem tratamento efetivo, como a osteoartrite (OA) em joelho. Nesse trabalho utilizamos células-tronco imaturas de polpa dentária humana (CTPD) cultivadas ou não em associação com biomateriais para o tratamento de lesões osteoarticulares em joelhos de ovinos. As CTPD humanas foram transduzidas com o gene repórter, EGFP, facilitando o monitoramento das mesmas in vitro e in vivo, apó...

  16. O uso de células-tronco na regeneração dos tecidos dentários e periodonto

    OpenAIRE

    Débora Milagres Ferreira

    2011-01-01

    Os estudos abordando a regeneração dos tecidos dentários ganharam uma nova perspectiva com a utilização das células-tronco. E novas perspectivas têm surgido com a bioengenharia tecidual e as terapias periodontais e pulpares regeneradoras. O objetivo deste trabalho foi desenvolver o modelo experimental de autotransplante em ratos visando compará-lo à técnica de reimplante e estudar a capacidade terapêutica das células da medula óssea em diferentes biomateriais utilizados como matriz para a ter...

  17. Caraterização dos utentes das consultas de periodontologia na Clínica Dentária Universitária Egas Moniz

    OpenAIRE

    Afonso, André Filipe Rodrigues

    2016-01-01

    Dissertação para obtenção do grau de Mestre no Instituto Superior de Ciências da Saúde Egas Moniz Objetivo: caraterizar os utentes das consultas de periodontologia da clínica dentária universitária Egas Moniz, procurando identificar os fatores de risco mais associados à doença periodontal (DP) desta população. Material e método: estudo observacional, analítico e transversal, efetuado numa amostra de conveniência de 150 utentes das consultas de periodontologia, aos quais se aplicou previ...

  18. Prótese valvular e o impacto na consulta de medicina dentária: um caso clínico

    OpenAIRE

    Gomes, Daniela de Araújo Gonçalves

    2016-01-01

    Dissertação para obtenção do grau de Mestre no Instituto Superior de Ciências da Saúde Egas Moniz Este caso clínico consiste na reabilitação oral de um paciente com prótese valvular cardíaca, apresentando um tratamento multidisciplinar que passa pelas áreas de Medicina Dentária Preventiva e Comunitária, Dentisteria, Periodontologia e Reabilitação Oral (prótese). Neste trabalho foi feito uma breve introdução sobre as cardiopatias dando principal foco nas valvulopatias, e, uma vez abordad...

  19. Materiais obturadores de canais radiculares de dentes decíduos: avaliação da atividade antibacteriana in vitro e da compatibilidade tecidual in vivo

    OpenAIRE

    2008-01-01

    Avaliou-se a atividade antibacteriana e a compatibilidade tecidual dos seguintes materiais obturadores de canais radiculares de dentes decíduos: cimento de óxido de zinco e eugenol, pasta Calen® espessada com óxido de zinco, cimento Sealapex® e cimento EndoREZTM. A atividade antibacteriana foi avaliada in vitro, por meio do teste de difusão em ágar, frente a 5 microrganismos indicadores (Kocuria rizophila, Enterococcus faecalis, Streptococcus mutans, Escherichia coli e Staphylococcus aureus)...

  20. Reflexões metodológicas sobre prevalência da fluorose dentária nos inquéritos de saúde bucal

    OpenAIRE

    Freitas, Cláudia Helena Soares de Morais; Fábio Correia SAMPAIO; Roncalli,Angelo Giuseppe; Moysés,Samuel Jorge

    2013-01-01

    OBJETIVO: Analisar limitações do estudo de fluorose dentária em inquéritos transversais. MÉTODOS: Foram utilizados dados dos estudos Condições de Saúde Bucal da População Brasileira (SBBrasil 2003) e da Pesquisa Nacional de Saúde Bucal (SBBrasil 2010). A estimativa de tendência epidemiológica da fluorose na população de 12 anos, aspectos da confiabilidade dos dados, bem como a precisão das estimativas, foram avaliadas nessas duas pesquisas. A distribuição da prevalência de fluoros...

  1. Caraterização dos utentes das consultas de periodontologia na Clínica Dentária Universitária Egas Moniz

    OpenAIRE

    Afonso, André Filipe Rodrigues

    2016-01-01

    Dissertação para obtenção do grau de Mestre no Instituto Superior de Ciências da Saúde Egas Moniz Objetivo: caraterizar os utentes das consultas de periodontologia da clínica dentária universitária Egas Moniz, procurando identificar os fatores de risco mais associados à doença periodontal (DP) desta população. Material e método: estudo observacional, analítico e transversal, efetuado numa amostra de conveniência de 150 utentes das consultas de periodontologia, aos quais se aplicou previ...

  2. CORROSION INHIBITION BY CASHEW NUT SHELL

    African Journals Online (AJOL)

    is the primary step in the action of organic corrosion inhibitors (Trabanelli. 1989). ... polarized. Electrochemical Impedance Spectroscopy (EIS) measurements .... solutions and UV/VIS to determine the adsorption of the CNSL inhibitor on.

  3. Fighting against corrosion; Kampf dem Substanzverlust

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2012-03-09

    Corrosion protection is not a new problem for the offshore industry, but requirements are particularly high in the wind power industry. There are hardly any international standards that could provide orientation.

  4. Fatigue - corrosion of endoprosthesis titanium alloys.

    Science.gov (United States)

    Cornet, A; Muster, D; Jaeger, J H

    1979-01-01

    Commercial total hip prostheses often show certain metallurgical faults (porosities, coarse grains, growth dendrites, carbide networks). In order to investigate more accurately the role played by these different parameters in prostheses failure we performed a large number of systematic corrosion, fatigue and fatigue - corrosion tests on these materials and on commercial total hip prostheses. Ultimate strengthes seem to be reached for cast cobalt alloys, whereas titanium alloys, such as Ta 6 V, present very high fatigue limit under corrosion. Thus, rotative bending fatigue - corrosion tests in biological environment provide values about 50 DaN/mm2. This value, is nevertheless appreciably higher than those obtained with stellites and stainless steel. Titanium alloys, because of their mechanical performances, their weak Young's modulus (11000 DaN/mm2) and their relative lightness (4.5. g/cm3), which are associated with a good biocompatibility, seem very promising for permanent implants realisation.

  5. High resolution in situ ultrasonic corrosion monitor

    Science.gov (United States)

    Grossman, R.J.

    1984-01-10

    An ultrasonic corrosion monitor is provided which produces an in situ measurement of the amount of corrosion of a monitoring zone or zones of an elongate probe placed in the corrosive environment. A monitoring zone is preferably formed between the end of the probe and the junction of the zone with a lead-in portion of the probe. Ultrasonic pulses are applied to the probe and a determination made of the time interval between pulses reflected from the end of the probe and the junction referred to, both when the probe is uncorroded and while it is corroding. Corresponding electrical signals are produced and a value for the normalized transit time delay derived from these time interval measurements is used to calculate the amount of corrosion.

  6. Polarized Neutron Reflectometry of Nickel Corrosion Inhibitors.

    Science.gov (United States)

    Wood, Mary H; Welbourn, Rebecca J L; Zarbakhsh, Ali; Gutfreund, Philipp; Clarke, Stuart M

    2015-06-30

    Polarized neutron reflectometry has been used to investigate the detailed adsorption behavior and corrosion inhibition mechanism of two surfactants on a nickel surface under acidic conditions. Both the corrosion of the nickel surface and the structure of the adsorbed surfactant layer could be monitored in situ by the use of different solvent contrasts. Layer thicknesses and roughnesses were evaluated over a range of pH values, showing distinctly the superior corrosion inhibition of one negatively charged surfactant (sodium dodecyl sulfate) compared to a positively charged example (dodecyl trimethylammonium bromide) due to its stronger binding interaction with the surface. It was found that adequate corrosion inhibition occurs at significantly less than full surface coverage.

  7. Localized Corrosion of Chromium Coated Steel

    NARCIS (Netherlands)

    Zhang, X.; Beentjes, P.; Mol, A.; Terryn, H.

    2006-01-01

    In this paper, we report on the studies of the local corrosion behaviour of chromium-coated ultra low carbon steel in NaCl solution using polarization, electrochemical impedance spectroscopy (EIS) and SVET.

  8. Amplified OTDR systems for multipoint corrosion monitoring.

    Science.gov (United States)

    Nascimento, Jehan F; Silva, Marcionilo J; Coêlho, Isnaldo J S; Cipriano, Eliel; Martins-Filho, Joaquim F

    2012-01-01

    We present two configurations of an amplified fiber-optic-based corrosion sensor using the optical time domain reflectometry (OTDR) technique as the interrogation method. The sensor system is multipoint, self-referenced, has no moving parts and can measure the corrosion rate several kilometers away from the OTDR equipment. The first OTDR monitoring system employs a remotely pumped in-line EDFA and it is used to evaluate the increase in system reach compared to a non-amplified configuration. The other amplified monitoring system uses an EDFA in booster configuration and we perform corrosion measurements and evaluations of system sensitivity to amplifier gain variations. Our experimental results obtained under controlled laboratory conditions show the advantages of the amplified system in terms of longer system reach with better spatial resolution, and also that the corrosion measurements obtained from our system are not sensitive to 3 dB gain variations.

  9. Amplified OTDR Systems for Multipoint Corrosion Monitoring

    Directory of Open Access Journals (Sweden)

    Joaquim F. Martins-Filho

    2012-03-01

    Full Text Available We present two configurations of an amplified fiber-optic-based corrosion sensor using the optical time domain reflectometry (OTDR technique as the interrogation method. The sensor system is multipoint, self-referenced, has no moving parts and can measure the corrosion rate several kilometers away from the OTDR equipment. The first OTDR monitoring system employs a remotely pumped in-line EDFA and it is used to evaluate the increase in system reach compared to a non-amplified configuration. The other amplified monitoring system uses an EDFA in booster configuration and we perform corrosion measurements and evaluations of system sensitivity to amplifier gain variations. Our experimental results obtained under controlled laboratory conditions show the advantages of the amplified system in terms of longer system reach with better spatial resolution, and also that the corrosion measurements obtained from our system are not sensitive to 3 dB gain variations.

  10. Electrochemical Corrosion of Carbon—Containing Refractories

    Institute of Scientific and Technical Information of China (English)

    CHENZhao-you

    1994-01-01

    The electrochemical examination on the cor-rosion of carbon or carbon containing refractiories at molten slag-liquid interface has been carried out.The electromotive force(E.M.F)of cells with different molten slags:C|molten slag | Fe at elevated temperatures has been measured by means of potentiometer and it is in the range from 250 to 450mV .It is found that the carbon electrode in these cells is anode and whn a counter E.M.F.is applied externally to the cel,the corrosion of carbon electrode will be sup-pressed entirely.Test results show that the local corrosion of carbon containing refractories at slag-metal interface is mainly caused by the mechanism of electrochemical corrosion.

  11. Há relação de hábitos orais deletérios com a tipologia facial e a oclusão dentária?

    Directory of Open Access Journals (Sweden)

    Cinthia Mara Johanns

    2011-12-01

    Full Text Available OBJETIVO: verificar se há predominância de hábitos orais deletérios nos diferentes tipos faciais eaprofundar o estudo da relação entre os hábitos orais deletérios e a oclusão dentária. MÉTODO: foram analisados 307 prontuários de pacientes entre 2 e 59 anos de idade de ambos os sexos, encaminhados ao ambulatório do Instituto CEFAC. Foram anotados dos prontuários os hábitos orais deletérios, oclusão dentária, tipologia facial, sexo e idade. RESULTADOS: observou-se que os hábitos com maior prevalência são: chupeta (125 indivíduos, ranger dentes (115 indivíduos e mamadeira (102 indivíduos. Dentre as comparações estudadas, as que apresentaram diferença estatisticamente significante foram: a presença do uso da chupeta no grupo de 9 a 12 anos, quando comparado ao de 6 a 9 anos (p=0,0269; presença do hábito de ranger dentes no grupo de 3 a 6 anos quando comparado ao grupo com mais de 20 anos (p=0,0393; presença do hábito de ranger dentes no grupo de oclusão dentária classe I quando comparado ao classe III (p=0,0128 e presença de oclusão dentária classe I no sexo feminino quando comparado ao masculino (p=0,0177. CONCLUSÃO: não há relação entre os hábitos orais deletérios e a tipologia facial. Entretanto, há relação entre o hábito oral deletério de ranger dentes com a oclusão dentária Classe I de Angle.

  12. Controlling Corrosion in Defence Equipment - Technical Meeting,

    Science.gov (United States)

    1985-10-01

    corrosion of Ni/Al bronze in neutral solution, (2) the inhibited corrosion of mild steel in sulphuric acid, (3) comparison and ranking of a number of... electropolish : alkaline clean: pumice scrub: anodic etch: chromium plate. It must be remembered that mild steel is not being used, but a low alloy steel ...Wolsley shows no such damage. After all they are both made - from similar steels and both have been exposed to the two essential ingredients required

  13. Preventing Corrosion by Controlling Cathodic Reaction Kinetics

    Science.gov (United States)

    2016-03-25

    Preventing corrosion by controlling cathodic reaction kinetics Progress Report for Period: 1 SEP 2015-31 MAR 2016 John Keith Department of...25 March 2016 Preventing corrosion by controlling cathodic reaction kinetics Annual Summary Report: FY16 PI: John Keith, 412-624-7016,jakeith...dominate the metal’s cathodic behavior. Within an alkaline environment, we expect the following reduction reactions to be catalyzed on the oxide

  14. Corrosion of surface defects in fine wires.

    Science.gov (United States)

    Rentler, R M; Greene, N D

    1975-11-01

    Defects were observed on the surfaces of various fine diameter wires commonly used in biomedical applications. These surface irregularities were viewed at high magnifications using a scanning electron microscope which has a much greater depth of field than normal light microscopy. Defects include scratches, pits, and crevices, which are the result of commercial wire drawing practices. Corrosion test results show that imperfections can serve as sites for localized corrosion attack which could lead to premature failures.

  15. METAL CORROSION IN WATERBORNE PRESERVATIVE- TREATED WOOD

    Directory of Open Access Journals (Sweden)

    Krisdianto Sugiyanto

    2010-12-01

    Full Text Available The rigidity and firmness of wooden construction and furniture those are joined by metal screws depend on corrosion rate of these metals. This paper examines the weight-loss percentage of metal screws used in wood samples that have been treated with water-borne preser vative (i.e.3% borax boric acid and 3% diffusol CB and concurrently investigates the effect of brake fluid on preventing metal corrosion. Wood samples tested included three acacia and one eucalypts wood species which were grouped into sapwood and heartwood containing samples. Wood samples fastened with metal screws were freely suspended in glass jars that contained 25 ml of sulphuric acid (H2SO4 to keep the humidity rate above 90%. After 12 months, the metal screws lost their weight due to the corrosion brought about by the related factors either in separate individual or in combination, which comprised brake and fluid-dipping , wood species, wood portion (sapwood and heartwood, kinds of preser vatives used. Corrosion rates of metal screws fastened in eucalypts wood sample as indicated by the screw-weight loss (i.e. 5.8% was more severe than that fastened in acacia wood. Furthermore, corrosion rate of metal screws as fixed firmly in sapwood sample proceeded faster than that in heartwood. This might be caused by the higher moisture content in sapwood. On the other hand, corrosion rate of the screws as fastened in waterborne-preser vative-treated wood samples was greater than that in non-preser ved wood due to electrokinetic characteristics and ionic potential exhibited by the preser vative thereby intensif ying the screw-corrosion process. Meanwhile, less severe corrosion was obser ved and recorded on the screws pre-dipped in brake fluid compared to those on the non-dipped screws

  16. Aqueous Corrosion Rates for Waste Package Materials

    Energy Technology Data Exchange (ETDEWEB)

    S. Arthur

    2004-10-08

    The purpose of this analysis, as directed by ''Technical Work Plan for: Regulatory Integration Modeling and Analysis of the Waste Form and Waste Package'' (BSC 2004 [DIRS 171583]), is to compile applicable corrosion data from the literature (journal articles, engineering documents, materials handbooks, or standards, and national laboratory reports), evaluate the quality of these data, and use these to perform statistical analyses and distributions for aqueous corrosion rates of waste package materials. The purpose of this report is not to describe the performance of engineered barriers for the TSPA-LA. Instead, the analysis provides simple statistics on aqueous corrosion rates of steels and alloys. These rates are limited by various aqueous parameters such as temperature (up to 100 C), water type (i.e., fresh versus saline), and pH. Corrosion data of materials at pH extremes (below 4 and above 9) are not included in this analysis, as materials commonly display different corrosion behaviors under these conditions. The exception is highly corrosion-resistant materials (Inconel Alloys) for which rate data from corrosion tests at a pH of approximately 3 were included. The waste package materials investigated are those from the long and short 5-DHLW waste packages, 2-MCO/2-DHLW waste package, and the 21-PWR commercial waste package. This analysis also contains rate data for some of the materials present inside the fuel canisters for the following fuel types: U-Mo (Fermi U-10%Mo), MOX (FFTF), Thorium Carbide and Th/U Carbide (Fort Saint Vrain [FSVR]), Th/U Oxide (Shippingport LWBR), U-metal (N Reactor), Intact U-Oxide (Shippingport PWR, Commercial), aluminum-based, and U-Zr-H (TRIGA). Analysis of corrosion rates for Alloy 22, spent nuclear fuel, defense high level waste (DHLW) glass, and Titanium Grade 7 can be found in other analysis or model reports.

  17. Reinforcement of dented pipeline through composite sleeve repair systems subjected to fatigue by internal pressure; Reparos de dutos com amassamento atraves de luvas de materiais compositos submetidos a fadiga por pressao interna

    Energy Technology Data Exchange (ETDEWEB)

    Perrut, Valber Azevedo; Meniconi, Luiz Claudio de Marco [Centro de Pesquisas da Petrobras (CENPES). Gerencia de Tecnologia de Materiais, Equipamentos e Corrosao (Brazil)], e-mails: vperrut@petrobras.com.br, meniconi@petrobras.com.br; Souza Filho, Byron Goncalvez de [Transpetro (Brazil)], e-mail: byron.souza@petrobras.com.br

    2008-12-15

    Composite sleeve repair systems, now of widespread use in the market, were originally developed for the reinforcement of corroded pipelines. TRANSPETRO, the Brazilian pipeline operator, requested PETROBRAS/CENPES to address the behavior of sleeves when applied to dented pipelines. Simple verification experiments were carried out, in which both the dent filler material and the sleeve material were varied. Artificial dents with depths of 19% OD were imposed to 22 in. OD, 0.5 in. thick, API 5L X60 tubular specimens. Concrete and polymeric materials were tested for dent filler, whereas glass and carbon fiber composites, in two different thicknesses, were tried as the sleeve structural material. The main purpose of the repair sleeve in this case is to provide a repair procedure installed at low temperature and capable of reducing the stress range at the hot spot in the dent. The goal is to improve the fatigue resistance of the repaired pipeline. Low cycle fatigue tests were performed, both using non-repaired specimens (to serve as the basis for comparison) and specimens repaired using different schemes. The tests were fully instrumented to analyze strains in each specimen. After the fatigue tests, each specimen was pressurized until collapse, in order to quantify their ultimate strength. This paper reports the main results of the tests and the strain analysis for each repaired specimen, with the purpose of defining parameters which will serve to the design of future cases. (author)

  18. Materials corrosion and protection at high temperatures; Corrosion et protection des materiaux a haute temperature

    Energy Technology Data Exchange (ETDEWEB)

    Balbaud, F.; Desgranges, Clara; Martinelli, Laure; Rouillard, Fabien [CEA-Saclay, DEN, DPC, SCCME, Laboratoire d' Etude de la Corrosion Non Aqueuse, 91191 Gif-sur-Yvette Cedex (France); Duhamel, Cecile [Mines ParisTech, Centre des materiaux UMR-CNRS 7633, BP 87, 91003 Evry Cedex (France); Marchetti, Loic; Perrin, Stephane [CEA, Laboratoire d' Etude de la Corrosion Aqueuse (France); Molins, Regine [Mines ParisTech, Direction de la Recherche, 60 Bvd Saint Michel, 75272 Paris Cedex 06 (France); Chevalier, S.; Heintz, O. [Laboratoire interdisciplinaire Carnot de Bourgogne, UMR 5209 CNRS, Univ. de Bourgogne, Dijon (France); David, N.; Fiorani, J.M.; Vilasi, M. [Institut Jean Lamour, UMR 7198, Univ. Henri Poincare Nancy-1 - CNRS, 54506 Vandoeuvre-les-Nancy (France); Wouters, Y.; Galerie, A. [SIMAP UMR CNRS 5266, Grenoble-INP/UJF, 1130 rue de la Piscine BP 75, 38402 Saint-Martin-d' Heres Cedex (France); Mangelinck, D. [IM2NP, UMR6242, CNRS, Univ. Paul Cezanne, Case 142, Faculte de Saint Jerome, 13397 Marseille Cedex 20 (France); Viguier, B.; Monceau, D. [Univ. de Toulouse, Institut Carnot CIRIMAT, INP-ENSIACET, 4 allee Emile Monso, BP 44362, 31030 Toulouse Cedex 4 (France); Soustelle, M. [Ecole nationale superieure des mines, Saint Etienne (France); Pijolat, M. [Centre Spin, Ecole des mines de Saint Etienne (France); Favergeon, J.; Brancherie, D.; Moulin, G.; Dawi, K. [Laboratoire Roberval, UTC (France); Wolski, K.; Barnier, V. [Centre SMS, EMSE, UMR 5146, LCG, Univ. de Lyon, 158 Cours Fauriel, 42023 Saint Etienne (France); Rebillat, F. [LCTS, Univ. de Bordeaux (France); Lavigne, O. [Onera, Dep. Materiaux et Structures Metalliques, BP 72, 29 av. de la Division Leclerc, 92322 Chatillon (France); Brossard, J.M. [Dep. energetique et procedes, Veolia Environnement Recherche et Innovation, Limay (France); Ropital, F. [IFP Energies Nouvelles, BP 3, 69360 Solaize (France); Mougin, J. [CEA-Liten, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France)

    2011-07-01

    This book was made from the lectures given in 2010 at the thematic school on 'materials corrosion and protection at high temperatures'. It gathers the contributions from scientists and engineers coming from various communities and presents a state-of-the-art of the scientific and technological developments concerning the behaviour of materials at high temperature, in aggressive environments and in various domains (aerospace, nuclear, energy valorization, and chemical industries). It supplies pedagogical tools to grasp high temperature corrosion thanks to the understanding of oxidation mechanisms. It proposes some protection solutions for materials and structures. Content: 1 - corrosion costs; macro-economical and metallurgical approach; 2 - basic concepts of thermo-chemistry; 3 - introduction to the Calphad (calculation of phase diagrams) method; 4 - use of the thermodynamic tool: application to pack-cementation; 5 - elements of crystallography and of real solids description; 6 - diffusion in solids; 7 - notions of mechanics inside crystals; 8 - high temperature corrosion: phenomena, models, simulations; 9 - pseudo-stationary regime in heterogeneous kinetics; 10 - nucleation, growth and kinetic models; 11 - test experiments in heterogeneous kinetics; 12 - mechanical aspects of metal/oxide systems; 13 - coupling phenomena in high temperature oxidation; 14 - other corrosion types; 15 - methods of oxidized surfaces analysis at micro- and nano-scales; 16 - use of SIMS in the study of high temperature corrosion of metals and alloys; 17 - oxidation of ceramics and of ceramic matrix composite materials; 18 - protective coatings against corrosion and oxidation; 19 - high temperature corrosion in the 4. generation of nuclear reactor systems; 20 - heat exchangers corrosion in municipal waste energy valorization facilities; 21 - high temperature corrosion in oil refining and petrochemistry; 22 - high temperature corrosion in new energies industry. (J.S.)

  19. Controlling internal corrosion of oil and gas pipelines : the corrosion inhibitor selection software (CISS) program

    Energy Technology Data Exchange (ETDEWEB)

    Doiron, A.; Papavinasam, S. [Natural Resources Canada, Ottawa, ON (Canada). CANMET Materials Technology Laboratory

    2009-07-01

    The internal pitting corrosion of oil and gas pipelines can be effectively controlled through the addition of inhibitors. However, simulation of field operating conditions is necessary because the performance of corrosion inhibitors is influenced by several interacting parameters. This paper reviewed the Corrosion Inhibitor Selection Software (CISS) program. The materials transported in production pipelines are often multiphase, containing oil, aqueous (brine), and gas phases. The corrosion rate and inhibitor performance are influenced by composition, temperature, flow and pressure. Steel composition and structure also influence both the rate and type of corrosion. Improvements in corrosion test methodologies are aimed at simulating field corrosion conditions in the laboratory in a compressed time-scale. The parameters that influence the types of corrosion must be simulated in order for laboratory methodology to be relevant. The variables controlled should be quantifiable. There should also be a correlation between the influence of variables controlled in the laboratory and of the same variables in the field. The CISS program evaluates inhibitors in the following 4 steps: (1) pipeline operating conditions, (2) selection of laboratory methodology, (3) determination of operating conditions for the laboratory methodologies, and (4) selection of corrosion inhibitors. The 7 objectives of the CISS program are to optimize the strategies of inhibitor selection for pipeline applications; determine the hydrodynamic parameters of the pipe from field operating conditions; select appropriate laboratory methodologies for evaluating inhibitors; determine flow conditions for high-shear laboratory methodologies; develop a qualitative relationship between corrosion rates of non-shear laboratory methodologies and of pipelines; evaluate corrosion inhibitors based on results from different laboratory methodologies; and design cost-effective inhibitors for future applications. 47 refs

  20. Silica nanocontainers for active corrosion protection

    Science.gov (United States)

    Maia, Frederico; Tedim, João; Lisenkov, Aleksey D.; Salak, Andrei N.; Zheludkevich, Mikhail L.; Ferreira, Mário G. S.

    2012-02-01

    Novel self-healing protective coatings with nanocontainers of corrosion inhibitors open new opportunities for long-term anticorrosion protection of different metallic materials. In this paper a new type of functional nanoreservoir based on silica nanocapsules (SiNC) synthesized and loaded with corrosion inhibitor 2-mercaptobenzothiazole (MBT) in a one-stage process is reported for the first time. Unlike conventional mesoporous silica nanoparticles, SiNC possess an empty core and shell with gradual mesoporosity, arising from the particular conditions of the synthetic route adopted, which confers significant loading capacity and allows prolonged and stimuli-triggered release of the inhibiting species. The kinetics of inhibitor release was studied at different pH values and concentrations of NaCl. The results show a clear dependence of the release profiles on corrosion relevant triggers such as pH and Cl- concentration. When SiNC loaded with MBT are dispersed in NaCl solution, there is a significant decrease of the corrosion activity on aluminium alloy 2024. More importantly, when SiNC-MBT is added to a conventional water-based coating formulation, the modified coating hampers corrosion activity at the metal interface, better than in the case of direct addition of corrosion inhibitor. Furthermore, self-healing is observed before and after artificially inflicting defects in the modified coatings. As a result, the developed nanocontainers show high potential to be used in new generation of active protective coatings.

  1. Theoretical Analysis of Reinforcement Tunnel Lining Corrosion

    Directory of Open Access Journals (Sweden)

    ZhiQiang Zhangand

    2013-05-01

    Full Text Available The main cause of ageing damage in reinforced concrete structures is reinforcement corrosion. Damage can be detected visually as coincident cracks along the reinforcement bar, which are significant of both reduction of the re-bar, cross-section and loss of bond strength for reinforced concrete. The reinforced concrete is one of the most widely used engineering materials as final lining of tunnels. The corrosion is common durability problems that have significant effect on the tunnel performance. This study intends to analysis reinforcement concrete corrosion at the tunnel lining by applying temperature expansion theory on steel through numerical simulation process, with expansive force effect. The thickness of concrete cover and the diameter of steel bar have an impact on the stress for reinforcement concrete during propagation of corrosion process. The corrosion cracks appear at the corner of a tunnel lining then in invert and vault because the maximum stress will be in the corner then in invert and vault. The internal force in the concrete lining changes differently when the corrosion rate change.

  2. Recent Developments on Autonomous Corrosion Protection Through Encapsulation

    Science.gov (United States)

    Li, W.; Buhrow, J. W.; Calle, L. M.; Gillis, M.; Blanton, M.; Hanna, J.; Rawlins, J.

    2015-01-01

    This paper concerns recent progress in the development of a multifunctional smart coating, based on microencapsulation, for the autonomous detection and control of corrosion. Microencapsulation has been validated and optimized to incorporate desired corrosion control functionalities, such as early corrosion detection and inhibition, through corrosion-initiated release of corrosion indicators and inhibitors, as well as self-healing agent release triggered by mechanical damage. While proof-of-concept results have been previously reported, more recent research and development efforts have concentrated on improving coating compatibility and synthesis procedure scalability, with a targeted goal of obtaining easily dispersible pigment-grade type microencapsulated materials. The recent progress has resulted in the development of pH-sensitive microparticles as a corrosion-triggered delivery system for corrosion indicators and inhibitors. The synthesis and early corrosion indication results obtained with coating formulations that incorporate these microparticles are reported. The early corrosion indicating results were obtained with color changing and with fluorescent indicators.

  3. Controlled-Release Microcapsules for Smart Coatings for Corrosion Applications

    Science.gov (United States)

    2008-01-01

    Corrosion is a serious problem that has enormous costs and serious safety implications. Localized corrosion, such as pitting, is very dangerous and can cause catastrophic failures. The NASA Corrosion Technology Laboratory at Kennedy Space Center is developing a smart coating based on pH-sensitive microcapsules for corrosion applications. These versatile microcapsules are designed to be incorporated into a smart coating and deliver their core content when corrosion starts. Corrosion indication was the first function incorporated into the microcapsules. Current efforts are focused on incorporating the corrosion inhibition function through the encapsulation of corrosion inhibitors into water core and oil core microcapsules. Scanning electron microscopy (SEM) images of encapsulated corrosion inhibitors are shown.

  4. Corrosion behaviour of non-ferrous metals in sea water

    Energy Technology Data Exchange (ETDEWEB)

    Birn, Jerzy; Skalski, Igor [Ship Design and Research Centre, Al. Rzeczypospolitej 8, 80-369 Gdansk (Poland)

    2004-07-01

    The most typical kinds of corrosion of brasses are selective corrosion (dezincification) and stress corrosion. Prevention against these kinds of corrosion lies in application of arsenic alloy addition and appropriate heat treatment removing internal stresses as well as in maintaining the arsenic and phosphorus contents on a proper level. The most typical corrosion of cupronickels is the local corrosion. Selective corrosion occurs less often and corrosion cracking caused by stress corrosion in sea water does not usually occur. Crevice corrosion is found especially in places of an heterogeneous oxidation of the surface under inorganic deposits or under bio-film. Common corrosive phenomena for brasses and cupronickels are the effects caused by sea water flow and most often the impingement attack. Alloy additions improve resistance to the action of intensive sea water flow but situation in this field requires further improvement, especially if the cheaper kinds of alloys are concerned. Contaminants of sea water such as ammonia and hydrogen sulphide are also the cause of common corrosion processes for all copper alloys. Corrosion of copper alloys may be caused also by sulphate reducing bacteria (SRB). Galvanic corrosion caused by a contact with titanium alloys e.g. in plate heat exchangers may cause corrosion of both kinds copper alloys. Bronzes belong to copper alloys of the highest corrosion resistance. Failures that sometimes occur are caused most often by the cavitation erosion, by an incorrect chemical composition of alloys or at last by their inadequate structure. The main problems of aluminium alloys service in sea water are following phenomena: local corrosion (pitting and crevice corrosion), galvanic corrosion, exfoliation and corrosion in the presence of OH- ions. The cause of local corrosion are caused by presence of passive film on the alloy's surface and presence of chlorides in sea water which are able to damage the passive film. Galvanic corrosion is

  5. Corrosion studies in brines of the Salton Sea Geothermal Field

    Energy Technology Data Exchange (ETDEWEB)

    Carter, J.P.; McCawley, F.X.; Cramer, S.D.; Needham, P.B. Jr.

    1979-01-01

    Toward the goal of maximizing minerals and metals recovery from domestic resources, the Bureau of Mines, U.S. Department of the Interior, has conducted in situ corrosion studies at the Salton Sea Known Geothermal Resources Area (KGRA) in the Imperial Valley, Calif., to evaluate and characterize materials of construction for geothermal resources recovery plants. General-, pitting, and crevice-corrosion characteristics of 13 commercially available alloys were investigated for periods of 15 and 30 days in seven process environments expected to be found in typical geothermal resources plants. Stainless steel alloy 29-4, Inconel 625, and the Hastelloys G, S, and C-276 were the most resistant to general corrosion, did not pit, and exhibited little susceptibility to crevice corrosion. Stainless steel alloys 430, E-Brite 26-1, and 6X had low general corrosion rates, but pitted and were susceptible to crevice corrosion. Stainless steel alloy 316 L had a low corrosion rate, but corroded intergranularly, pitted, and was susceptible to crevice corrosion and to stress-corrosion cracking. Titanium--1.5 nickel and TiCode-12 had low corrosion rates, did not pit, and were not susceptible to crevice corrosion. Carbon and 4130 steels had high corrosion rates, pitted, and had high susceptibilities to crevice corrosion. The major scale-forming mineral on the corrosion samples in most of the process environments studied was galena mixed with lesser amounts of other minerals.

  6. Corrosion Behavior of S450EW Low-alloy Weathering Steel in Cyclically Alternate Corrosion Environments

    Institute of Scientific and Technical Information of China (English)

    Jun-shan WANG; Pei-yang SHI; Cheng-jun LIU; Mao-fa JIANG

    2015-01-01

    Weathering steel is widely used in various ifelds due to its excellent mechanical properties and high corrosion resistance. The effect of chromium content on the S450EW weathering steel in cyclic immersion test was studied. The results indicated that the corrosion resistance of S450EW weathering steel is closely related to chromium content. The addition of chromium signiif-cantly inhibited the weathering steel corrosion. The corrosion rate of experimental steel after 96 h immersion was 1.101 g·m−2·h−1. The rust of S450EW weathering steel was mainly constituted of FeOOH and Fe3O4 phase, and the elevation of chromium content promoted the formation of α-FeOOH. The ifne precipitates of the two phases contributed to the formation of dense dust layer of test steel. Furthermore, the increase of chromium is beneifcial for the cure of original defects and cracks of the rust layer via the enrich-ment of chromium. The corrosion potential and the resistance of corrosion process were thus increased, protecting the experimental steel from further corrosion. A S450EW steel with corrosion resistance more than 1.5 times of Q450NQR1 steel was prepared.

  7. The Corrosion Inhibition Characteristics of Sodium Nitrite Using an On-line Corrosion Rate Measurement System

    Energy Technology Data Exchange (ETDEWEB)

    Park, Mal-Yong; Kang, Dae-Jin [Korea Polytechnic University, Shiheung (Korea, Republic of); Moon, Jeon-Soo [Future Technology Research Laboratory, KEPCO Research Institute, Daejeon (Korea, Republic of)

    2015-04-15

    An on-line corrosion rate measurement system was developed using a personal computer, a data acquisition board and program, and a 2-electrode corrosion probe. Reliability of the developed system was confirmed with through comparison test. With this system, the effect of sodium nitrite (NaNO{sub 2}) as a corrosion inhibitor were studied on iron and aluminum brass that were immersed in sodium chloride (NaCl) solution. Corrosion rate was measured based on the linear polarization resistance method. The corrosion rates of aluminum brass and iron in 1% NaCl solutions were measured to be 0.290 mm per year (mmpy) and 0.2134 mmpy, respectively. With the addition of 200 ppm of NO{sub 2}{sup -}, the corrosion rates decreased to 0.0470 mmpy and 0.0254 mmpy. The addition of NO{sub 2}{sup -} caused a decrease in corrosion rates of both aluminum brass and iron, yet the NO{sub 2}{sup -} acted as a more effective corrosion inhibitor for iron. than aluminum brass.

  8. A study of microbial population dynamics associated with corrosion rates influenced by corrosion control materials

    NARCIS (Netherlands)

    Chang, Yu Jie; Hung, Chun Hsiung; Lee, Jyh Wei; Chang, Yi Tang; Lin, Fen Yu; Chuang, Chun Jie

    2015-01-01

    This research aims to analyze the variations of microbial community structure under anaerobic corrosive conditions, using molecular fingerprinting method. The effect of adding various materials to the environment on the corrosion mechanism has been discussed. In the initial experiment, sulfate-re

  9. NASA's Beachside Corrosion Test Site and Current Environmentally Friendly Corrosion Control Initiatives

    Science.gov (United States)

    Russell, Richard W.; Calle, Luz Marina; Johnston, Frederick; Montgomery, Eliza L.; Curran, Jerome P.; Kolody, Mark R.

    2013-01-01

    NASA began corrosion studies at the Kennedy Space Center (KSC) in 1966 during the Gemini/Apollo Programs with the evaluation of long-term corrosion protective coatings for carbon steel. KSC's Beachside Corrosion Test Site (BCTS), which has been documented by the American Society of Materials (ASM) as one of the most corrosive, naturally occurring, environments in the world, was established at that time. With the introduction of the Space Shuttle in 1981, the already highly corrosive conditions at the launch pad were rendered even more severe by the acid ic exhaust from the solid rocket boosters. In the years that followed, numerous studies have identified materials, coatings, and maintenance procedures for launch hardware and equipment exposed to the highly corrosive environment at the launch pad. This paper presents a historical overview of over 45 years of corrosion and coating evaluation studies and a description of the BCTS's current capabilities. Additionally, current research and testing programs involving chromium free coatings, environmentally friendly corrosion preventative compounds, and alternates to nitric acid passivation will be discussed.

  10. A study of microbial population dynamics associated with corrosion rates influenced by corrosion control materials

    NARCIS (Netherlands)

    Chang, Yu Jie; Hung, Chun Hsiung; Lee, Jyh Wei; Chang, Yi Tang; Lin, Fen Yu; Chuang, Chun Jie

    2015-01-01

    This research aims to analyze the variations of microbial community structure under anaerobic corrosive conditions, using molecular fingerprinting method. The effect of adding various materials to the environment on the corrosion mechanism has been discussed. In the initial experiment,

  11. Cloning and characterization of CLCN5, the human kidney chloride channel gene implicated in Dent disease (an X-linked hereditary nephrolithiasis)

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, S.E.; Van Bakel, I.; Craig, I.W. [Univ. of Oxford (United Kingdom)] [and others

    1995-10-10

    Dent disease, an X-linked familial renal tubular disorder, is a form of Fanconi syndrome associated with proteinuria, hypercalciuria, nephrocalcinosis, kidney stones, and eventual renal failure. We have previously used positional cloning to identify the 3{prime} part of a novel kidney-specific gene (initially termed hClC-K2, but now referred to as CLCN5), which is deleted in patients from one pedigree segregating Dent disease. Mutations that disrupt this gene have been identified in other patients with this disorder. Here we describe the isolation and characterization of the complete open reading frame of the human CLCN5 gene, which is predicted to encode a protein of 746 amino acids, with significant homology to all known members of the ClC family of voltage-gated chloride channels. CLCN5 belongs to a distinct branch of this family, which also includes the recently identified genes CLCN3 and CLCN4. We have shown that the coding region of CLCN5 is organized into 12 exons, spanning 25-30 kb of genomic DNA, and have determined the sequence of each exon-intron boundary. The elucidation of the coding sequence and exon-intron organization of CLCN5 will both expedite the evaluation of structure/function relationships of these ion channels and facilitate the screening of other patients with renal tubular dysfunction for mutations at this locus. 31 refs., 5 figs.

  12. 'Dented' and 'resuscitated' masculinities: the impact of HIV diagnosis and/or enrolment on antiretroviral treatment on masculine identities in rural eastern Uganda.

    Science.gov (United States)

    Siu, Godfrey E; Wight, Daniel; Seeley, Janet

    2014-01-01

    There is limited research on the impact of HIV or its treatment on men's identity construction and gender roles in sub-Saharan Africa. Based on in-depth research with 26 men in rural Uganda, this article discusses men's vulnerabilities and shifting gender relations and sense of masculinity resulting from HIV infection or enrolment on treatment in eastern Uganda. The findings suggest two broad categories of masculinity: respectable and reputational. HIV infection and illness dented masculinity as men lost authority within the domestic sphere. A weakened provider role and over-reliance on wives and children undermined masculinity as family head, and social sanctioning of their sexual activity, undermined conventional masculine identities predicted on reputation. However, treatment led to a more reflexive approach to demonstrating masculinity, increased attentiveness to health and restored hope to father children free of HIV, resuscitating respectable masculinities. The balance between eroded and restored masculinity varied between men by their treatment history, age, family composition and state of health. HIV support agencies need to pay attention to the way HIV and antiretroviral treatment (ART) influence men's perception of their masculinity and support them to overcome the anxieties about dented or eroded masculinity, while building on the positive ways in which treatment restores masculinity to support men's adherence to HIV treatment. In particular, there is a need to support men's engagement in productive activities that bring income so that men can regain their provider roles following ART and restore their respectability in both the public and the domestic sphere.

  13. Dente intranasal em portador de fissura de lábio e palato: relato de caso Intranasal tooth in patient with cleft lip and palate: case report

    Directory of Open Access Journals (Sweden)

    Aline Rogéria F. de Castilho

    2004-12-01

    Full Text Available A presença de dentes na cavidade nasal é rara e inclui alguns sinais e sintomas característicos, como obstrução nasal, rinite casual e odor fétido, entre outros, que podem ser confundidos com outras patologias. Por esta razão, o diagnóstico diferencial deve ser bem executado, por meio dos exames clínico e radiográfico da região. O tratamento, geralmente, é cirúrgico e pode prevenir complicações secundárias. O presente trabalho apresenta um caso de dente intranasal e seu respectivo tratamento cirúrgico para remoção.The presence of teeth at the nasal cavity is rare and involves some characteristic signs and symptoms, such as nasal obstruction, eventual rhinitis and fetid smell, and also others that may be confused with other pathologies. Therefore, differential diagnosis should be carefully accomplished by means of clinical and radiographic examinations of the area. Treatment is usually surgical and may prevent secondary complications. The present paper presents a case of intranasal tooth and the respective surgical treatment for its removal.

  14. Analysis of corrosion failure of petrochemical pipe elbow

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-yan; L(U) Tao

    2005-01-01

    Corrosive failure is frequently found in petrochemical pipelines which may lead to the leakage of the pipes and even the shutdown of the system. However, the corrosion mechanism is still not well understood due to the complex service environment, e.g. the corrosive fluids and the long term operation at higher temperature. The corrosion behaviour of a petrochemical pipe elbow was evaluated via visual examination and microanalysis with optical microscope and scanning electron microscope(SEM) together with energy dispersive analysis X-ray (EDAX). The corresponding corrosion mechanisms, the combination of grain boundary attach and the crevice attach together with the flow-accelerated corrosion, were proposed consequently.

  15. Estudo de prevalência das agenesias dentárias, numa população de pacientes da Clínica da Faculdade de Ciências da Saúde da Universidade Fernando Pessoa

    OpenAIRE

    Malta, Ana Margarida Afonso

    2012-01-01

    Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária Introdução: A ausência congénita de um ou mais dentes é a anomalia de desenvolvimento dentário mais comum no Homem (Vastardis, 2000). O conhecimento da sua prevalência torna-se indispensável na compreensão da sua importância clínica, relacionada com o desequilíbrio provocado no sistema Estomatognático, manifestando-se na desarmonia o...

  16. Distribuição dos mastócitos nas fases intra-óssea e submucosa na erupção dentária humana

    OpenAIRE

    Franzolin, Solange de Oliveira Braga

    2009-01-01

    A erupção dos dentes decíduos e permanentes é um processo fisiológico que acompanha o desenvolvimento do ser humano por aproximadamente duas décadas. Vários mecanismos biológicos controlam a odontogênese, erupção e esfoliação fisiológica dos decíduos até o estabelecimento dos dentes permanentes na arcada. A fim de elucidar aspectos anatômicos e fisiológicos relacionados à erupção dentária, sua sintomatologia e outros sinais clínicos, decidiu-se investigar a presença de mastócito nos tecidos p...

  17. High temperature corrosion during biomass firing: improved understanding by depth resolved characterisation of corrosion products

    DEFF Research Database (Denmark)

    Okoro, Sunday Chukwudi; Montgomery, Melanie; Jappe Frandsen, Flemming

    2015-01-01

    The high temperature corrosion of an austenitic stainless steel (TP 347H FG), widely utilised as a superheater tube material in Danish power stations, was investigated to verify the corrosion mechanisms related to biomass firing. KCl coated samples were exposed isothermally to 560 degrees C...... changes within the near surface region (covering both the deposit and the steel surface). Such cross-section analysis was further complemented by plan view investigations (additionally involving X-ray diffraction) combined with removal of the corrosion products. Improved insights into the nature...... of the corrosion products as a function of distance from the deposit surface were revealed through this comprehensive characterisation. Corrosion attack during simulated straw-firing conditions was observed to occur through both active oxidation and sulphidation mechanisms....

  18. Relação entre dentes mal posicionados e a condição dos tecidos periodontais Association between malpositioned teeth and periodontal disease

    Directory of Open Access Journals (Sweden)

    Estela Santos Gusmão

    2011-08-01

    Full Text Available OBJETIVO: avaliar pacientes encaminhados à Associação Brasileira de Odontologia, Seção Pernambuco, para tratamento periodontal, a fim de identificar as anomalias de posição dentária presentes na amostra, bem como verificar se há relação entre essas anomalias e a condição dos tecidos periodontais. MÉTODOS: a amostra foi constituída por 90 indivíduos, com idades de 15 a 69 anos. Inicialmente, cada participante foi submetido à identificação dos tipos de anomalias de posição dentária através de exame de inspeção visual e, posteriormente, à avaliação da condição periodontal, registrada pelos seguintes parâmetros clínicos: sangramento gengival na sondagem, perda de inserção periodontal e profundidade de sondagem. Na análise bivariada utilizou-se o teste Qui-quadrado para calcular o nível de significância das associações testadas. RESULTADOS: foram identificados vários tipos de alterações na posição dentária dos pacientes examinados, sendo os mais significativos: giroversão (86,7%, apinhamento (52,2% e molar inclinado mesialmente (48,9%. Em todos os participantes foram registradas alterações periodontais relacionadas a essas anomalias: 100% apresentaram sangramento gengival; 67,8%, recessão gengival; 54,4%, hiperplasia gengival e 28,9%, periodontite crônica.Verificou-se associação significativa entre a recessão gengival e as variáveis dente vestibularizado e proclinação excessiva dos incisivos superiores; e entre a periodontite crônica e molar inclinado mesialmente, dentes apinhados, proclinação excessiva dos incisivos superiores e inferiores, e diastema (pOBJECTIVE: To identify malpositioned teeth in patients referred to periodontal treatment in the Brazilian Association of Dentistry, Pernambuco Division and evaluate the association of these irregularities with periodontal health. METHODS: The sample comprised 90 individuals aged 15 to 69 years. First, each participant was examined to identify

  19. Cultural significance of primary teeth for caregivers in Northeast Brazil O significado cultural dos dentes decíduos para cuidadoras no Nordeste do Brasil

    Directory of Open Access Journals (Sweden)

    Marilyn K Nations

    2008-04-01

    Full Text Available This anthropological study critically evaluates Brazilian caregivers' symbolic production and significance of their malnourished offspring's primary teeth, as well as their own, and describes popular dental practices. From January to June 2004, ethnographic interviews of 27 poor, low-literacy mothers were conducted at a public Malnutrition Treatment Center in Fortaleza, Ceará State. Participant observation of clinical pathways and home environments supplemented the data. Content analysis was performed. Results confirm that primary teeth are imbued with cultural significance in Northeast Brazil. Mothers examine mouths, perceive signs of decay, associate primary with permanent tooth healthiness, identify ethnodental illnesses, seek assistance, and perform rituals with exfoliated teeth. The mother's motivation to care for primary teeth is sparked by her memories of past toothache and attempts to avoid stigma and discrimination. Social determinants, not mothers' beliefs or behaviors, are the most critical obstacles to effective dental care. Legitimizing lay knowledge and empowering caregivers and children can improve oral health in Northeast Brazil.Este estudo antropológico analisa a produção simbólica de cuidadoras brasileiras sobre a sua dentição e a de seus filhos desnutridos, descrevendo práticas populares de cuidados em saúde bucal. De janeiro a junho de 2004, foram conduzidas entrevistas etnográficas com 27 cuidadoras, numa instituição pública, no tratamento de desnutrição em Fortaleza, Ceará. A observação participante da dinâmica de atendimento e do ambiente domiciliar suplementaram os dados. Foi utilizada a análise temática. Os resultados confirmam que os dentes decíduos são imbuídos de significados culturais no nordeste brasileiro. As mães examinam as bocas dos filhos, percebem sinais de cárie, associam dentes decíduos saudáveis com permanentes hígidos, identificam enfermidades etnodentárias, procuram assist

  20. Abrasão a ar: efeito no preparo cavitário e na microinfiltração em dentes decíduos = Air Abrasion: effect on cavity preparation and on microleakage in primary teeth

    Directory of Open Access Journals (Sweden)

    Antunes, Lívia Azeredo Alves

    2014-01-01

    Full Text Available Objetivo: Comparar os efeitos da abrasão a ar e ponta diamantada de alta rotação sobre a topografia de preparos cavitários e a microinfiltração em dentes decíduos. Métodos: Neste estudo in vitro, as cavidades foram preparadas nas superfícies de 60 dentes, utilizando ambas as técnicas em cada dente. Vinte dentes foram escolhidos aleatoriamente para uma análise descritiva da topografia. Metade dos dentes restantes (20 foram tratados com um sistema adesivo de condicionamento total e a outra metade tratada com um sistema adesivo auto-condicionante e todas as amostras foram restauradas com resina. Depois disso, as amostras foram preparadas para os testes de microinfiltração e avaliadas por dezenas. Os dados estatísticos foram avaliados e um nível de significância de 5 % foi adotado para todos os testes. Resultados: A técnica de abrasão a ar produziu topografia diferenciada e aumentou a formação da camada de smear layer (Test qui-quadrado Stuart -Maxwell, p=0,03. Infiltração não foi influenciada por qualquer um dos sistemas de adesivos usados para preparações de cavidade (teste de Wilcoxon, p=0,08. No entanto, a ponta diamantada de alta rotação proporcionou mais infiltração independente do adesivo utilizado (Mann-Whitney, p=0,04; p=0,01. Conclusão: A técnica de abrasão a ar demonstrou ser uma boa alternativa para a prevenção de infiltração durante a preparação da cavidade em dentes decíduos

  1. CORROSION ISSUES ASSOCIATED WITH AUSTENITIC STAINLESS STEEL COMPONENTS USED IN NUCLEAR MATERIALS EXTRACTION AND SEPARATION PROCESSES

    Energy Technology Data Exchange (ETDEWEB)

    Mickalonis, J.; Louthan, M.; Sindelar, R.

    2012-12-17

    This paper illustrated the magnitude of the systems, structures and components used at the Savannah River Site for nuclear materials extraction and separation processes. Corrosion issues, including stress corrosion cracking, pitting, crevice corrosion and other corrosion induced degradation processes are discussed and corrosion mitigation strategies such as a chloride exclusion program and corrosion release testing are also discussed.

  2. Análise in vitro da presença de infiltração apical em dentes apicectomizados com técnica convencional e com o Laser de Er:YAG

    OpenAIRE

    Marques, Aparecida Maria Cordeiro

    2004-01-01

    110f. O grande número de insucessos na Cirurgia Paraendodôntica está diretamente relacionado à falhas no selamento do remanescente dentário apicectomizado e conseqüente manutenção de um ambiente propício à perpetuação de processos infecciosos. Com intuito de compreender melhor este aspecto, este trabalho tem como objetivo verificar e comparar ?in vitro?, a infiltração apical, através do uso de uma solução evidenciadora de Azul de Metileno a 2%, em dentes apicectomizados pela técnica conven...

  3. Avaliação da influência da arquitetura gengival na percepção estética do sorriso pelos pacientes e estudantes de Medicina Dentária

    OpenAIRE

    Dória, Rita Melo Alves Figueiredo

    2014-01-01

    Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Medicina Dentária A estética do sorriso depende da harmonia de diversos fatores, entre os quais se, destacam: contorno facial, arquiteturas dentária e gengival. Este estudo analisou qualitativamente a perceção dos pacientes quanto aos parâmetros de micro-estética da arquitetura gengival do setor anterior da cavidade oral, bem como o aspeto do...

  4. Estudo clínico e radiográfico do formocresol de Buckley diluído a 1/5 e do cimento Portland utilizados para pulpotomia em dentes decíduos humanos

    OpenAIRE

    Ana Paula Camolese Fornetti

    2007-01-01

    O objetivo deste estudo foi comparar a eficácia clínica e radiográfica do formocresol de Buckley diluído a 1/5 e do cimento Portland como agentes capeadores pulpares em dentes decíduos humanos acometidos por cárie extensa. Sessenta e oito molares decíduos inferiores de 52 crianças com idades entre 5 e 9 anos foram criteriosamente selecionados. Os dentes foram aleatoriamente divididos nos grupos formocresol ou cimento Portland e tratados pela técnica convencional de pulpotomia. Após a remoção ...

  5. MEJORAMIENTO DE LA CALIDAD DEL SERVICIO MEDIANTE LA IMPLEMENTACIÓN DE UN SISTEMA DE GESTIÓN DE CALIDAD EN LA EMPRESA MISTER DENT DEL DISTRITO DE TRUJILLO

    OpenAIRE

    2016-01-01

    El presente trabajo de investigación se realizó con el objetivo de determinar el mejoramiento de la calidad del servicio mediante la implementación de un sistema de gestión de calidad en la satisfacción del cliente en la Empresa MÍSTER DENT del Distrito de Trujillo / La Libertad. La investigación es un tipo de estudio cuantitativa y experimental. La población estuvo conformada por la calidad del servicio al cliente de la Empresa MÍSTER DENT, por lo que nuestra premuestra y pos muestra fue...

  6. Traumatismos dentários em adolescentes: prevalência e associação com fatores socioeconômicos e consumo de drogas ilícitas e álcool

    OpenAIRE

    Kelly Oliva Jorge

    2010-01-01

    O traumatismo dentário é considerado um problema de saúde pública entre adolescentes brasileiros. Embora existam muitos estudos sobre a prevalência, fatores etiológicos e predisponentes do traumatismo dentário, uma abordagem mais ampla, investigando fatores sociais como padrão socioeconômico das famílias, e sua associação com o consumo de drogas ilícitas e de álcool ainda é bastante carente na literatura. Diante disso, realizou-se um estudo transversal através de exame clínico feito por pesqu...

  7. Técnica de replicação de raízes dentárias em resina composta fotopolimerizável a partir de molde de resina acrílica autopolimerizável

    OpenAIRE

    Sergio Luiz da Silveira Camargo

    2011-01-01

    Pelas fraturas que sofrem os dentes caninos, torna-se necessário tratá-los endodonticamente, e repará-los proteticamente. Porém, novas fraturas coronais, com ou sem perda de coroa metálica podem se repetir. Muitas técnicas restauradoras priorizam os dentes com maior percentual de porção coronal, porque a extensa área de coroa remanescente assegura execução facilitada, favorecendo a recuperação do elemento dental e garantindo sucesso do assentamento da peça metálica. As pesquisas realizadas pa...

  8. Surface films and corrosion of copper

    Energy Technology Data Exchange (ETDEWEB)

    Hilden, J.; Laitinen, T.; Maekelae, K.; Saario, T.; Bojinov, M. [VTT Manufacturing Technology, Espoo (Finland)

    1999-03-01

    In Sweden and Finland the spent nuclear fuel is planned to be encapsulated in cast iron canisters that have an outer shield made of copper. The copper shield is responsible for the corrosion protection of the canister construction. General corrosion of the copper is not expected to be the limiting factor in the waste repository environment when estimating the life-time of the canister construction. However, different forms of localised corrosion, i.e. pitting, stress corrosion cracking, or environmentally assisted creep fracture may cause premature failure of the copper shield. Of the probable constituents in the groundwater, nitrites, chlorides, sulphides and carbonates have been suggested to promote localised corrosion of copper. The main assumption made in planning this research program is that the surface films forming on copper in the repository environment largely determine the susceptibility of copper to the different forms of localised corrosion. The availability of reactants, which also may become corrosion rate limiting, is investigated in several other research programs. This research program consists of a set of successive projects targeted at characterising the properties of surface films on copper in repository environment containing different detrimental anions. A further aim was to assess the significance of the anion-induced changes in the stability of the oxide films with regard to localised corrosion of copper. This report summarises the results from a series of investigations on properties of surface films forming on copper in water of pH = 8.9 at temperature of 80 deg C and pressure of 2 MPa. The main results gained so far in this research program are as follows: The surface films forming on copper in the thermodynamic stability region of monovalent copper at 80 deg C consist of a bulk part (about 1 mm thick) which is a good ionic and electronic conductor, and an outer, interfacial layer (0.001 - 0.005 mm thick) which shows p-type semiconductor

  9. Corrosion Evaluation of RERTR Uranium Molybdenum Fuel

    Energy Technology Data Exchange (ETDEWEB)

    A K Wertsching

    2012-09-01

    As part of the National Nuclear Security Agency (NNSA) mandate to replace the use of highly enriched uranium (HEU) fuel for low enriched uranium (LEU) fuel, research into the development of LEU fuel for research reactors has been active since the late 1970’s. Originally referred to as the Reduced Enrichment for Research and Test Reactor (RERTR) program the new effort named Global Threat Reduction Initiative (GTRI) is nearing the goal of replacing the standard aluminum clad dispersion highly enriched uranium aluminide fuel with a new LEU fuel. The five domestic high performance research reactors undergoing this conversion are High Flux Isotope reactor (HFIR), Advanced Test Reactor (ATR), National Institute of Standards and Technology (NIST) Reactor, Missouri University Research Reactor (MURR) and the Massachusetts Institute of Technology Reactor II (MITR-II). The design of these reactors requires a higher neutron flux than other international research reactors, which to this point has posed unique challenges in the design and development of the new mandated LEU fuel. The new design utilizes a monolithic fuel configuration in order to obtain sufficient 235U within the LEU stoichoimetry to maintain the fission reaction within the domestic test reactors. The change from uranium aluminide dispersion fuel type to uranium molybdenum (UMo) monolithic configuration requires examination of possible corrosion issues associated with the new fuel meat. A focused analysis of the UMo fuel under potential corrosion conditions, within the ATR and under aqueous storage indicates a slow and predictable corrosion rate. Additional corrosion testing is recommended for the highest burn-up fuels to confirm observed corrosion rate trends. This corrosion analysis will focus only on the UMo fuel and will address corrosion of ancillary components such as cladding only in terms of how it affects the fuel. The calculations and corrosion scenarios are weighted with a conservative bias to

  10. ESTUDO DA DISTRIBUIÇÃO DAS TENSÕES INTERNAS, SOB CARGA AXIAL, EM DENTE HÍGIDO E EM DENTE RESTAURADO COM COROA METALOCERÂMICA E RETENTOR INTRA-RADICULAR FUNDIDO: - MÉTODO DO ELEMENTO FINITO FINITE ELEMENT ANALYSIS OF INTERNAL STRESS DISTRIBUTION, UNDER AXIAL FORCE, IN SOUND TOOTH, AND IN TOOTH RESTORED WITH METALLOCERAMIC CROWN AND CAST METAL POST AND CORE

    Directory of Open Access Journals (Sweden)

    Matsuyoshi MORI

    1997-04-01

    Full Text Available Estudou-se comparativamente, pelo método do elemento finito em modelo bidimensional de segundo pré-molar inferior, a distribuição de tensões internas, geradas sob carga axial de 30 kgf em três pontos (contatos principal e estabilizante, em dente natural hígido e em dente endodonticamente tratado. O programa utilizado para o processamento do elemento finito foi o SAP90. Os resultados indicaram maior acúmulo de tensões na metade vestibular, tanto no dente hígido quanto no dente restaurado. As tensões foram mais intensas sob o ponto de aplicação de cargas nos dois modelos. No dente restaurado, as tensões foram maiores devido ao maior módulo de elasticidade dos materiais restauradores, demonstrando que existem diferenças na distribuição das tensões no dente e na base óssea dos dois modelosThis study compared the internal stress distribution in a sound tooth with that in an endodontically treated tooth, by the finite element method, in a two-dimensional, lower premolar model, under an axial load of 30 kgf applied to three points (primary occlusal contact and stabilizing occlusal contact. Results indicated that there was a greater cumulation of stress in the buccal half of both teeth. In both models, peak stress was observed at the places where loads were applied. The restored tooth presented greater stress due to the greater Young's modulus of the utilized restoring materials. It was therefore demonstrated that there are differences in the distribution of internal stress between both models

  11. Remote measurement of corrosion using ultrasonic techniques

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, K.M.; Porter, A.M.

    1995-02-01

    Supercritical water oxidation (SCWO) technology has the potential of meeting the US Department of Energy`s treatment requirements for mixed radioactive waste. A major technical constraint of the SCWO process is corrosion. Safe operation of a pilot plant requires monitoring of the corrosion rate of the materials of construction. A method is needed for measurement of the corrosion rate taking place during operation. One approach is to directly measure the change in wall thickness or growth of oxide layer at critical points in the SCWO process. In FY-93, a brief survey of the industry was performed to evaluate nondestructive evaluation (NDE) methods for remote corrosion monitoring in supercritical vessels. As a result of this survey, it was determined that ultrasonic testing (UT) methods would be the most cost-effective and suitable method of achieving this. Therefore, the objective for FY-94 was to prove the feasibility of using UT to monitor corrosion of supercritical vessels remotely during operation without removal of the insulation.

  12. Analyses of containment structures with corrosion damage

    Energy Technology Data Exchange (ETDEWEB)

    Cherry, J.L. [Sandia National Labs., Albuquerque, NM (United States)

    1997-01-01

    Corrosion damage that has been found in a number of nuclear power plant containment structures can degrade the pressure capacity of the vessel. This has prompted concerns regarding the capacity of corroded containments to withstand accident loadings. To address these concerns, finite element analyses have been performed for a typical PWR Ice Condenser containment structure. Using ABAQUS, the pressure capacity was calculated for a typical vessel with no corrosion damage. Multiple analyses were then performed with the location of the corrosion and the amount of corrosion varied in each analysis. Using a strain-based failure criterion, a {open_quotes}lower bound{close_quotes}, {open_quotes}best estimate{close_quotes}, and {open_quotes}upper bound{close_quotes} failure level was predicted for each case. These limits were established by: determining the amount of variability that exists in material properties of typical containments, estimating the amount of uncertainty associated with the level of modeling detail and modeling assumptions, and estimating the effect of corrosion on the material properties.

  13. Monitoring corrosion in reinforced concrete structures

    Science.gov (United States)

    Kung, Peter; Comanici, Maria I.

    2014-06-01

    Many defects can cause deterioration and cracks in concrete; these are results of poor concrete mix, poor workmanship, inadequate design, shrinkage, chemical and environmental attack, physical or mechanical damage, and corrosion of reinforcing steel (RS). We want to develop a suite of sensors and systems that can detect that corrosion is taking place in RS and inform owners how serious the problem is. By understanding the stages of the corrosion process, we can develop special a sensor that detects each transition. First, moisture ingress can be monitored by a fiber optics humidity sensor, then ingress of Chloride, which acts as a catalyst and accelerates the corrosion process by converting iron into ferrous compounds. We need a fiber optics sensor which can quantify Chloride ingress over time. Converting ferric to ferrous causes large volume expansion and cracks. Such pressure build-up can be detected by a fiber optic pressure sensor. Finally, cracks emit acoustic waves, which can be detected by a high frequency sensor made with phase-shifted gratings. This paper will discuss the progress in our development of these special sensors and also our plan for a field test by the end of 2014. We recommend that we deploy these sensors by visually inspecting the affected area and by identifying locations of corrosion; then, work with the designers to identify spots that would compromise the integrity of the structure; finally, drill a small hole in the concrete and insert these sensors. Interrogation can be done at fixed intervals with a portable unit.

  14. Corrosion and arc erosion in MHD channels

    Energy Technology Data Exchange (ETDEWEB)

    Rosa, R.J. (Montana State Univ., Bozeman, MT (United States). Dept. of Mechanical Engineering); Pollina, R.J. (Montana State Univ., Bozeman, MT (United States). Dept. of Mechanical Engineering EG and G Energy Measurements, Inc., Las Vegas, NV (United States))

    1992-08-01

    The problems connected with gas side corrosion for the design of the lA4 (POC) channel hardware are explored and results of gas side wear rate tests in the Textron Mark VII facility are presented. It is shown that the proposed designs meet a 2000 hour lifetime criterion based upon these materials tests. Improvement in cathode lifetime is demonstrated with lower voltage intercathode gaps. The corrosion of these materials is discussed and it is shown how lifetimes are dependent upon gap voltage and average metal temperature. The importance of uniformity of slagging to the durability of the anode wall is demonstrated. The wear mechanism of the anodes in the MHD channel is analyzed. In addition to gas-side corrosion, the results of specific water corrosion tests of sidewall materials are discussed. All of the tests reported here were carried out to confirm the gas-side performance and the manufacturability of anode and sidewall designs and to address questions posed about the durability of tungsten-copper on the waterside. the results of water corrosion tests of the tungsten copper alloy sidewall material are presented to show that with proper control of waterside pH and, if necessary, dissolved oxygen, one can obtain reliable performance with no degradation of heat transfer with this material. The final choice of materials was determined primarily by the outcome of these tests and also by the question of the manufacturability of the prospective designs.

  15. Handbook of corrosion data, 2nd edition

    Energy Technology Data Exchange (ETDEWEB)

    Craig, B.; Anderson, D. [eds.

    1995-12-31

    As in the prior edition, in one convenient volume this book makes it easy to find what effect environment has on the corrosion of metals and alloys. Coverage on all the environments in the first edition has been updated and expanded and some 80 or more environments have been added, including food products (chocolate, milk, cider, beer, etc.), fruit juices (grape, pineapple, lemon, etc.), soil, blood, gasoline, fertilizers, etc. Presentation of the tabular information for all environments has been standardized throughout the book. The environments are listed alphabetically. Each listing includes a general description of the conditions, a comment on the corrosion characteristics of various alloys in such a situation, a bibliography of recent articles specific to the environment, tables consolidating and comparing corrosion rates at various temperatures and concentrations for various alloys, and graphical information. also included are summaries on the general corrosion characteristics of major metals and alloys. This separate section of the book considers each material group, such as aluminum, stainless steel, zinc and so forth. Additional tables are presented here to give the corrosion characteristics of various alloys in hundreds of environments.

  16. Anomalous dissolution of metals and chemical corrosion

    Directory of Open Access Journals (Sweden)

    DRAGUTIN M. DRAZIC

    2005-03-01

    Full Text Available An overview is given of the anomalous behavior of some metals, in particular Fe and Cr, in acidic aqueous solutions during anodic dissolution. The anomaly is recognizable by the fact that during anodic dissolutionmore material dissolves than would be expected from the Faraday law with the use of the expected valence of the formed ions. Mechanical disintegration, gas bubble blocking, hydrogen embrittlement, passive layer cracking and other possible reasons for such behavior have been discussed. It was shown, as suggested by Kolotyrkin and coworkers, that the reason can be, also, the chemical reaction in which H2O molecules with the metal form metal ions and gaseous H2 in a potential independent process. It occurs simultaneously with the electrochemical corrosion process, but the electrochemical process controls the corrosion potential. On the example of Cr in acid solution itwas shown that the reason for the anomalous behavior is dominantly chemical dissolution, which is considerably faster than the electrochemical corrosion, and that the increasing temperature favors chemical reaction, while the other possible reasons for the anomalous behavior are of negligible effect. This effect is much smaller in the case of Fe, but exists. The possible role of the chemical dissolution reacton and hydrogen evolution during pitting of steels and Al and stress corrosion cracking or corrosion fatigue are discussed.

  17. Corrosion-Resistant High-Entropy Alloys: A Review

    Directory of Open Access Journals (Sweden)

    Yunzhu Shi

    2017-02-01

    Full Text Available Corrosion destroys more than three percent of the world’s gross domestic product. Therefore, the design of highly corrosion-resistant materials is urgently needed. By breaking the classical alloy-design philosophy, high-entropy alloys (HEAs possess unique microstructures, which are solid solutions with random arrangements of multiple elements. The particular locally-disordered chemical environment is expected to lead to unique corrosion-resistant properties. In this review, the studies of the corrosion-resistant HEAs during the last decade are summarized. The corrosion-resistant properties of HEAs in various aqueous environments and the corrosion behavior of HEA coatings are presented. The effects of environments, alloying elements, and processing methods on the corrosion resistance are analyzed in detail. Furthermore, the possible directions of future work regarding the corrosion behavior of HEAs are suggested.

  18. Evaluation of Encapsulated Inhibitor for Autonomous Corrosion Protection

    Science.gov (United States)

    Johnsey, M. N.; Li, W.; Buhrow, J. W.; Calle, L. M.; Pearman, B. P.; Zhang, X.

    2015-01-01

    This work concerns the development of smart coating technologies based on microencapsulation for the autonomous control of corrosion. Microencapsulation allows the incorporation of corrosion inhibitors into coating which provides protection through corrosion-controlled release of these inhibitors.One critical aspect of a corrosion protective smart coating is the selection of corrosion inhibitor for encapsulation and comparison of the inhibitor function before and after encapsulation. For this purpose, a systematic approach is being used to evaluate free and encapsulated corrosion inhibitors by salt immersion. Visual, optical microscope, and Scanning Electron Microscope (with low-angle backscatter electron detector) are used to evaluate these inhibitors. It has been found that the combination of different characterization tools provide an effective method for evaluation of early stage localized corrosion and the effectiveness of corrosion inhibitors.

  19. A rapid stress-corrosion test for aluminum alloys

    Science.gov (United States)

    Helfrich, W. J.

    1968-01-01

    Stressed alloy specimens are immersed in a salt-dichromate solution at 60 degrees C. Because of the minimal general corrosion of these alloys in this solution, stress corrosion failures are detected by low-power microscopic examination.

  20. Low Toxicity Corrosion Inhibitors for Smart Coatings Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Kennedy Space Center (KSC) is located near one of the most corrosive natural environments in the world. Corrosion of KSC ground assets is exacerbated by the...

  1. A physical corrosion model for bioabsorbable metal stents.

    Science.gov (United States)

    Grogan, J A; Leen, S B; McHugh, P E

    2014-05-01

    Absorbable metal stents (AMSs) are an emerging technology in the treatment of heart disease. Computational modelling of AMS performance will facilitate the development of this technology. In this study a physical corrosion model is developed for AMSs based on the finite element method and adaptive meshing. The model addresses a gap between currently available phenomenological corrosion models for AMSs and physical corrosion models that have been developed for more simple geometries than those of a stent. The model developed in this study captures the changing surface of a corroding three-dimensional AMS structure for the case of diffusion-controlled corrosion. Comparisons are made between model predictions and those of previously developed phenomenological corrosion models for AMSs in terms of predicted device geometry and mechanical performance during corrosion. Relationships between alloy solubility and diffusivity in the corrosion environment and device performance during corrosion are also investigated.

  2. Biofilms: strategies for metal corrosion inhibition employing microorganisms.

    Science.gov (United States)

    Zuo, Rongjun

    2007-10-01

    Corrosion causes dramatic economic loss. Currently widely used corrosion control strategies have disadvantages of being expensive, subject to environmental restrictions, and sometimes inefficient. Studies show that microbial corrosion inhibition is actually a common phenomenon. The present review summarizes recent progress in this novel strategy: corrosion control using beneficial bacteria biofilms. The possible mechanisms may involve: (1) removal of corrosive agents (such as oxygen) by bacterial physiological activities (e.g., aerobic respiration), (2) growth inhibition of corrosion-causing bacteria by antimicrobials generated within biofilms [e.g., sulfate-reducing bacteria (SRB) corrosion inhibition by gramicidin S-producing Bacillus brevis biofilm], (3) generation of protective layer by biofilms (e.g., Bacillus licheniformis biofilm produces on aluminum surface a sticky protective layer of gamma-polyglutamate). Successful utilization of this novel strategy relies on advances in study at the interface of corrosion engineering and biofilm biology.

  3. PH and Electrochemical Responsive Materials for Corrosion Smart Coating Applications

    Science.gov (United States)

    Li, Wenyan; Calle, Luz M.

    2008-01-01

    Corrosion is a costly issue for military operations and civil industries. While most corrosion initiates from localized corrosion form, such as pitting, failure directly caused by localized corrosion is the most dangerous kind, because it is difficult to anticipate and prevent, occurs very suddenly and can be catastrophic. One way of preventing these failures is with a coating that can detect and heal localized corrosion. pH and other electrochemical changes are often associated with localized corrosion, so it is expected that materials that are pH or otherwise electrochemical responsive can be used to detect and control corrosion. This paper will review various pH and electrochemical responsive materials and their potential applications in corrosion smart coatings. Current research results in this field will also be reported.

  4. Concrete cover cracking with localized corrosion of reinforcing steel

    Energy Technology Data Exchange (ETDEWEB)

    Torres-Acosta, A. A.; Sagues, A. A. [South Florida Univ., Dept of Civil and Environmental Engineering, Tampa FL (United States)

    2000-07-01

    The critical amount of steel corrosion needed for concrete cover cracking of a reinforced concrete element was measured, focusing on cases where only a fraction of the steel bar length is corroding. The amount of corrosion needed to crack the concrete cover was found to range between 49 micrometre to 137 micrometre in specimens of localized corrosion. In contrast, in cases of uniform corrosion of comparable systems the corrosion needed to crack the concrete cover varied from 15 micrometre to 75 micrometer. Based on this and previous work on this problem, an empirical equation is proposed for the critical amount of steel corrosion as a function of specimen dimensions. The model proposed for estimating the critical amount of steel corrosion showed reasonable agreement between estimates of the work of corrosion expansion and the energy required to crack the concrete. 23 refs., 3 tabs., 8 figs.

  5. effect of municipal liquid waste on corrosion susceptibility of ...

    African Journals Online (AJOL)

    DR. AMINU

    The corrosion rate of the galvanized steel pipe was measured using the gravimetric technique. ... three stagnant liquid waste samples collected outside the city (SLW4,SLW5, and ... increased exposure time, a layer of protective corrosion ...

  6. pH Responsive Microcapsules for Corrosion Control

    Science.gov (United States)

    Calle, Luz Marina; Li, Wenyan; Muehlberg, Aaron; Boraas, Samuel; Webster, Dean; JohnstonGelling, Victoria; Croll, Stuart; Taylor, S Ray; Contu, Francesco

    2008-01-01

    The best coatings for corrosion protection provide not only barriers to the environment, but also a controlled release of a corrosion inhibitor, as demanded by the presence of corrosion or mechanical damage. NASA has developed pH sensitive microcapsules (patent pending) that can release their core contents when corrosion starts. The objectives of the research presented here were to encapsulate non-toxic corrosion inhibitors, to incorporate the encapsulated inhibitors into paint formulations, and to test the ability of the paints to control corrosion. Results showed that the encapsulated corrosion inhibitors, specifically Ce(NO3)3 , are effective to control corrosion over long periods of time when incorporated at relatively high pigment volume concentrations into a paint formulation.

  7. Detection of microbiologically influenced corrosion by electrochemical noise transients

    NARCIS (Netherlands)

    Homborg, A.M.; Morales, C.F. Leon; Tinga, Tiedo; de Wit, J.H.W.; Mol, J.M.C.

    2014-01-01

    This work investigates the electrochemical processes involved in pitting corrosion induced by microbiologically influenced corrosion by using time-resolved instantaneous frequency information of electrochemical current noise (ECN) transients obtained from Hilbert spectra. In addition to the

  8. Corrosion circumstance in the Tokai Reprocessing Plant and evaluation of the corrosion rate

    Energy Technology Data Exchange (ETDEWEB)

    Maki, Akira [Japan Nuclear Cycle Development Inst., Tokai Works, Tokai Reprocessing Center, Tokai, Ibaraki (Japan)

    2002-03-01

    In the reprocessing plant, corrosive circumstances arise, because the major equipment contains a high concentration of the metal ions that originate from the fission products. They are also equipped in the various concentrations of nitric acid and various temperatures. Based on failed experiments due to corrosion, repairing the equipment and exchanging materials, the corrosion rate of stainless steel containing Nb was measured over 1 mm/yr in the heat transfer surface of the dissolver. Pin-holes in the weld zone of the heat conduction surface of the dissolver and the acid recovery evaporator were observed. Although the corrosion rate of Ti-5Ta in the vapor zone of the plutonium solution evaporator reached 0.1 - 0.3 mm/yr, no local attacks were confirmed. On the other hand, the corrosion of Ti-5Ta was not observed in the acid recovery evaporator. This report presents the survey result of the corrosion equipment and an outline of the corrosion tests, with the wall thickness measurement result obtained as a soundness confirmation of the equipment. (author)

  9. Penetration of corrosion products and corrosion-induced cracking in reinforced cementitious materials

    DEFF Research Database (Denmark)

    Michel, Alexander; Pease, Brad J.; Peterova, Adela;

    2014-01-01

    This paper describes experimental investigations on corrosion-induced deterioration in reinforced cementitious materials and the subsequent development and implementation of a novel conceptual model. Rejnforced mortar specimens of varying water-to-cement ratios were subjected to current-induced c......This paper describes experimental investigations on corrosion-induced deterioration in reinforced cementitious materials and the subsequent development and implementation of a novel conceptual model. Rejnforced mortar specimens of varying water-to-cement ratios were subjected to current......-induced corrosion (10, 50, and 100 mu A/cm(2)). X-ray attenuation measurements and visual investigations provided both qualitative and quantitative information on the penetration of solid corrosion products into the surrounding cementitious matrix. X-ray attenuation measurements provided time- and location......-dependent concentrations of corrosion products averaged through the specimen thickness. Digital image correlation (DIC) was used to measure corrosion-induced deformations including deformations between steel and cementitious matrix as well as formation and propagation of corrosion-induced cracks. Based on experimental...

  10. Corrosion monitoring as an integral component of an effective corrosion management program

    Energy Technology Data Exchange (ETDEWEB)

    Bich, N.N. [FORCE Technology Canada Inc., Calgary, AB (Canada)

    2004-07-01

    This paper presented 6 case studies of oil and sour gas transmission pipelines where the use of corrosion monitoring devices led to the early identification of ineffective mitigation measures. The field signature method inspection tool (FSM-IT) was used in all 6 cases. FSM-IT is a non-intrusive corrosion monitoring tool that consists of a geometric matrix of sensing pins that are permanently attached to an outer pipe wall. The sensing matrix wiring is coupled to a sensing matrix interface (SMI) to form an interface. With the occurrence of internal corrosion or erosion, the electrical field is changed and compared against the signature. Computer software is used to compare the new measurements against the original signature to produce metal loss values. The software is capable of trending the metal loss over time, calculating corrosion rates and creating 3D plots to illustrate accumulated wall loss over the whole matrix. The orientation of the corrosion can be determined from an evaluation of the plots. Case studies included details of pipeline length, corrosion mechanisms, and repair activities. Mitigation measures in the case studies included batching; continuous injection; and pigging. It was concluded that the FSM-IT corrosion mitigation tool is effective in monitoring mitigation effectiveness. 7 refs., 1 tab., 12 figs.

  11. Corrosion of Carbon Steel and Corrosion-Resistant Rebars in Concrete Structures Under Chloride Ion Attack

    Science.gov (United States)

    Mohamed, Nedal; Boulfiza, Mohamed; Evitts, Richard

    2013-03-01

    Corrosion of reinforced concrete is the most challenging durability problem that threatens reinforced concrete structures, especially structures that are subject to severe environmental conditions (i.e., highway bridges, marine structures, etc.). Corrosion of reinforcing steel leads to cracking and spalling of the concrete cover and billions of dollars are spent every year on repairing such damaged structures. New types of reinforcements have been developed to avoid these high-cost repairs. Thus, it is important to study the corrosion behavior of these new types of reinforcements and compare them to the traditional carbon steel reinforcements. This study aimed at characterizing the corrosion behavior of three competing reinforcing steels; conventional carbon steel, micro-composite steel (MMFX-2) and 316LN stainless steel, through experiments in carbonated and non-carbonated concrete exposed to chloride-laden environments. Synthetic pore water solutions have been used to simulate both cases of sound and carbonated concrete under chloride ions attack. A three-electrode corrosion cell is used for determining the corrosion characteristics and rates. Multiple electrochemical techniques were applied using a Gamry PC4™ potentiostat manufactured by Gamry Instruments (Warminster, PA). DC corrosion measurements were applied on samples subjected to fixed chloride concentration in the solution.

  12. Mophologic Analysis of the teeth and his relation with the slaughter age of buffalos ANÁLISE MORFOLÓGICA DOS DENTES E SUA RELAÇÃO COM A IDADE DE ABATE DE BÚFALOS

    Directory of Open Access Journals (Sweden)

    Francisco Carneiro Lima

    2008-07-01

    Full Text Available t was evaluated to the morphology of the incisors teeth of 100 buffaloes of slaughterhouses in Sao Luiz, seeking to relate them with your age of slaughter. The dental arches of the buffalos were taken to the laboratory of Anatomy/UEMA, for analysis of the incisors teeth. The results showed that the incisors teeth was composed for 4 pair, disposed in semicircle, denominated of 1ts, 2nd, 3rt and 4th pairs of incisors teeth (tweezers, first medium, seconds medium and songs. It was evidenced two teethings, deciduous and definitive, with forms and varied sizes, and variables levels of dental wear and tear, besides the presence of longitudinal grooves in the surface of the deciduous and definitive teeth with coloration varying from brown clear to darkness. With the dental analysis it was possible to distinguish five groups of animals that are depressed in the Maranhão and the group of smaller animals than 2.5 years and larger than 5.5 years were the more frequently observed. After morphologic and chronological evaluation of the incisors teeth of buffaloes, it was conclude that the buffaloes present a dental morphology similar the others ruminants and that, in function of the dental observation, the depressed buffaloes in Maranhão don’t follow pattern defined for discard.

    KEY WORD: Anatomy, buffaloes, teeth, slaughter.

    Avaliou-se a morfologia dos dentes incisivos de cem bubalinos adultos abatidos em matadouros do município de São Luís, Maranhão, visando relacioná-los com a idade de seu abate. Coletaram-se as arcadas dentárias desses animais, as quais foram levadas para o laboratório de Anatomia do Curso de Medicina Veterinária/UEMA, para análise dos dentes incisivos. Os resultados mostraram

  13. Influence of environmental factors on corrosion damage of aircraft structure

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Corrosion is one of the important structural integrity concerns of aging aircraft, and it is estimated that a significant portion of airframe maintenance budgets is directed towards corrosion-related problems for both military and commercial aircraft. In order to better understand how environmental factors influence the corrosion damage initiation and propagation on aircraft structure and to predict pre-corrosion test pieces of fatigue life and structural integrity of an effective approach, this paper uses ...

  14. On-line Corrosion Monitoring in District Heating Systems

    DEFF Research Database (Denmark)

    Richter, Sonja; Thorarinsdottir, R.I.; Hilbert, Lisbeth Rischel

    2005-01-01

    The corrosion control in district heating systems is today performed primarily with control of the water quality. The corrosion rate is kept low by assuring low dissolved oxygen concentration, high pH and low conductivity. Corrosion failures can occur, e.g. as a result of unknown oxygen ingress......, precipitation of deposits or crevices. The authors describe methods used for on-line monitoring of corrosion, cover the complications and the main results of a Nordic project....

  15. Aluminum Composites With Small Nanoparticles Additions: Corrosion Resistance

    OpenAIRE

    Agureev, L.E.; Kostikov, V.I.; Eremeeva, Zh.V.; Barmin, A.A.; Savushkina, S.V.; Ivanov, B.S.

    2016-01-01

    International audience; Research of corrosion resistance of the aluminum powder composites containing microadditives (0.01 – 0.15% is executed about.) zirconium oxide nanoparticles. Extreme dependence of speed of corrosion of aluminum composites in 10-% solutions of sulfuric and nitric acid from the maintenance of nanoadditives is shown. It has been shown the dynamics of mass loss of aluminum composites with nanoparticles of ZrO2 during corrosion tests in acids solutions. The lowest corrosion...

  16. Online, real-time corrosion monitoring in district heating systems

    DEFF Research Database (Denmark)

    Hilbert, Lisbeth Rischel; Thorarinsdottir, R.I.

    2005-01-01

    The corrosion control in district heating systems is today performed primarily with control of the water quality. The corrosion rate is kept low by assuring low dissolved oxygen concentration, high pH and low conductivity. Corrosion failures can occur, e.g. as a result of unknown oxygen ingress......, precipitation of deposits or crevices. The authors describe methods used for on-line monitoring of corrosion, cover the complications and the main results of a Nordic project....

  17. Corrosion and wear resistant metallic layers produced by electrochemical methods

    DEFF Research Database (Denmark)

    Christoffersen, Lasse; Maahn, Ernst Emanuel

    1999-01-01

    Corrosion and wear-corrosion properties of novel nickel alloy coatings with promising production characteristics have been compared with conventional bulk materials and hard platings. Corrosion properties in neutral and acidic environments have been investigated with electrochemical methods....... Determination of polarisation resistance during 100 hours followed by stepwise anodic polarisation seems to be a promising technique to obtain steady state data on slowly corroding coatings with transient kinetics. A slurry test enables determination of simultaneous corrosion and abrasive wear. Comparison...

  18. Modeling of Discontinuities in Resistance Structures due to Corrosion

    Directory of Open Access Journals (Sweden)

    Daniel Boboş

    2011-05-01

    Full Text Available The corrosion process is a process that produces significant negative effects on the resistance structures by reducing their section and by deterioration of mechanical properties of materials. In this paper are presented some notions about the corrosion process, types of corrosion encountered and types of geometric models that can be used for analytical calculation and for numerical simulation using finite element analysis programs, of the effects produced in the corrosion process on the natural frequency of the structure elements.

  19. Review of Artificial Neural Networks (ANN) applied to corrosion monitoring

    Science.gov (United States)

    Mabbutt, S.; Picton, P.; Shaw, P.; Black, S.

    2012-05-01

    The assessment of corrosion within an engineering system often forms an important aspect of condition monitoring but it is a parameter that is inherently difficult to measure and predict. The electrochemical nature of the corrosion process allows precise measurements to be made. Advances in instruments, techniques and software have resulted in devices that can gather data and perform various analysis routines that provide parameters to identify corrosion type and corrosion rate. Although corrosion rates are important they are only useful where general or uniform corrosion dominates. However, pitting, inter-granular corrosion and environmentally assisted cracking (stress corrosion) are examples of corrosion mechanisms that can be dangerous and virtually invisible to the naked eye. Electrochemical noise (EN) monitoring is a very useful technique for detecting these types of corrosion and it is the only non-invasive electrochemical corrosion monitoring technique commonly available. Modern instrumentation is extremely sensitive to changes in the system and new experimental configurations for gathering EN data have been proven. In this paper the identification of localised corrosion by different data analysis routines has been reviewed. In particular the application of Artificial Neural Network (ANN) analysis to corrosion data is of key interest. In most instances data needs to be used with conventional theory to obtain meaningful information and relies on expert interpretation. Recently work has been carried out using artificial neural networks to investigate various types of corrosion data in attempts to predict corrosion behaviour with some success. This work aims to extend this earlier work to identify reliable electrochemical indicators of localised corrosion onset and propagation stages.

  20. Recent Natural Corrosion Inhibitors for Mild Steel: An Overview

    OpenAIRE

    Marko Chigondo; Fidelis Chigondo

    2016-01-01

    Traditionally, reduction of corrosion has been managed by various methods including cathodic protection, process control, reduction of the metal impurity content, and application of surface treatment techniques, as well as incorporation of suitable alloys. However, the use of corrosion inhibitors has proven to be the easiest and cheapest method for corrosion protection and prevention in acidic media. These inhibitors slow down the corrosion rate and thus prevent monetary losses due to metalli...