This work was carried out aiming the study of the corrosion effect by the water produced, which is associate to the production of oil, mainly in wells in mature fields, such as the UN-SEAL. It is noteworthy that this water is known in the petroleum industry as water produced. The sample of produced water used was of the production field of Siririzinho I on-shore in Sergipe, which showed in its physicalchemical analysis, high levels of salinity among other compounds, which makes it an extremely aggressive corrosion for materials used in the petroleum industry. In this research the materials used in this work were the carbon steel ASTM A283 Gr C, the stainless steel ASTM A240 type 316L with and without coating of hard chrome and the duplex stainless steel ASTM A890 Gr 1B. The sample used had chemical compositions issued by manufacturers according to ASTM, in addition, microhardness tests and metallographic tests with the use of optical microscopy were used to characterize these materials. For the study of effect of the water produced attack in the materials, was designed and built a test circuit, which allowed the insertion of samples for monitoring and data collected of mass and thickness parameters , and the monitoring visual corrosion during the test. The samples were machined in two geometric shapes (rectangular plate and disk) to enable and facilitate the testing of weight and thickness measurement by applying the ultrasound technique and of the depth measurement. From the collected data was possible to calculate by established criteria using the standard NACE RP 0775, the rate of uniform corrosion by mass loss and by its development the rate of corrosion by thickness loss, that is the same form used for the calculation of corrosion rate by pit in agreement with the standard Petrobras N- 2364. By comparing the corrosion rates obtained in the study, can better evaluate the possible perspectives of application of the materials in contact with the corrosive fluid. / Este trabalho foi desenvolvido objetivando o estudo do efeito da corrosão por meio da água que está associada à produção do petróleo, principalmente em poços de campos maduros, como é o caso da UN-SEAL. Ressalta-se que esta água é conhecida na indústria do petróleo como água produzida. A amostra da água produzida utilizada foi a do campo de produção de Siririzinho I do ativo de produção de Sergipe Terra que apresentou em sua análise físico-química, altos teores de salinidade dentre outros compostos que a torna um meio extremamente agressivo à corrosão para os materiais utilizados na indústria do petróleo. Nesta pesquisa os materiais estudados foram os aços: carbono ASTM A283 Gr. C, o inox ASTM A240 tipo 316L sem e com revestimento de cromo duro e o inox duplex ASTM A890 Gr. 1B. As amostras utilizadas possuíam suas composições químicas emitidas pelos fabricantes de acordo com a norma ASTM, além disto, ensaios de microdureza e ensaios metalográficos com o uso da microscopia óptica foram utilizados na caracterização destes materiais. Para o estudo do efeito do ataque da água produzida nos materiais, foi projetado e construído um circuito de teste, o qual permitiu a inserção de corpos de prova para monitoramento e coleta de dados dos parâmetros de massa e de espessura, além do acompanhamento visual da corrosão ao longo do teste. Os corpos de prova foram usinados em duas formas geométricas (disco e placa retangular) de modo a permitir e facilitar a realização dos ensaios de medição de massa, medição de espessura através do ultra-som e da medição de profundidade. De posse dos dados coletados foi possível calcular através de critérios estabelecidos pela norma NACE RP 0775, a taxa de corrosão uniforme por perda de massa e por seu desenvolvimento a taxa de corrosão por perda de espessura, que é a mesma forma utilizada para o cálculo da taxa de corrosão por pites segundo a norma Petrobras N-2364. Através das taxas de corrosão obtidas no estudo, pode-se avaliar quais as possíveis perspectivas de aplicação dos materiais em contato com o fluido corrosivo.

Submitted by Pedro Silva Filho (pfsilva@ipen.br) on 2017-11-17T16:32:32Z No. of bitstreams: 0 / Made available in DSpace on 2017-11-17T16:32:32Z (GMT). No. of bitstreams: 0 / Os aços inoxidáveis duplex são largamente utilizados na fabricação de equipamentos para a indústria de óleo e gás, utilizados tanto no ambiente onshore quanto offshore. Sua grande limitação é que, com o aumento de temperatura, ocorre precipitação de fases indesejáveis, que reduzem drasticamente a resistência à corrosão e as propriedades mecânicas desses materiais. Considerando o efeito deletério da soldagem a fusão nos aços inoxidáveis duplex, a soldagem por atrito com pino não-consumível (FSW) é amplamente considerada como alternativa aos processos convencionais. Como no FSW a união dos materiais ocorre no estado sólido, muitos dos problemas de soldabilidade associados às técnicas tradicionais de soldagem por fusão são evitados. Neste trabalho, amostras retiradas da zona misturada (ZM), das zonas afetadas pelo calor (ZTA e ZTMA) e do metal de base (MB) de chapas de aço inoxidável lean duplex LDX 2404&reg (UNS S82441) soldadas por atrito com pino não-consumível foram caracterizadas microestruturalmente e tiveram sua resistência à corrosão avaliada por meio de ensaios eletroquímicos. Os resultados obtidos nos ensaios eletroquímicos indicaram que as zonas afetadas pelo calor e a ZM se mantiveram tão resistentes à corrosão localizada quanto o MB. Permitiram concluir também que a excelente resistência à corrosão da liga está associada ao teor elevado de N. / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

Submitted by Pedro Silva Filho (pfsilva@ipen.br) on 2017-11-21T11:56:39Z No. of bitstreams: 0 / Made available in DSpace on 2017-11-21T11:56:39Z (GMT). No. of bitstreams: 0 / O processo de soldagem por fricção e mistura (FSW) tem despertado grande interesse nos últimos anos e tornou-se uma alternativa para unir materiais de baixa soldabilidade, como as ligas de alumínio das séries 2XXX e 7XXX, as quais são empregadas na estrutura das aeronaves, por possuírem elevada relação resistência/peso. O processo FSW, todavia, causa mudanças microestruturais nos materiais soldados, particularmente na zona misturada (ZM) e nas zonas termicamente (ZTA) ou termomecanicamente (ZTMA) afetadas. Estas mudanças geralmente interferem no desempenho frente à corrosão das ligas soldadas. No presente estudo, a resistência à corrosão das ligas de alumínio 2024-T3 e 7475-T761, unidas pelo processo FSW foi investigada em solução 10 mM de NaCl. Ensaios de visualização em gel ágar-ágar e de imersão associados a técnicas microscópicas foram realizados para investigar o efeito do acoplamento galvânico na corrosão das diferentes regiões da junta soldada. Os resultados do ensaio de visualização em gel mostraram que, quando acopladas, a liga 2024 atua como cátodo e a 7475 como ânodo. Os ensaios de imersão revelaram acoplamento galvânico entre as ligas na zona misturada (ZM). A região mais afetada pela corrosão foi a ZTMA da liga 7475, com corrosão intergranular desde as primeiras horas de imersão. A influência do processo de soldagem na resistência à corrosão das duas ligas de alumínio foi investigada por ensaios eletroquímicos. Os ensaios eletroquímicos adotados foram medidas de potencial de circuito aberto (PCA) em função do tempo de exposição ao meio corrosivo, espectroscopia de impedância eletroquímica (EIE) e curvas de polarização potenciodinâmica. Os ensaios de polarização mostraram elevada atividade eletroquímica na zona de mistura indicada pelos altos valores de densidade de corrente em comparação com as demais zonas testadas. Os resultados de EIE globais mostraram que nas primeiras horas de exposição ao eletrólito o processo de corrosão foi predominantemente controlado pela liga 7475; todavia, com o tempo de exposição ao eletrólito, a corrosão passou a ser controlada pela liga 2024. / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

This master thesis is focused on producing orthopaedic implant materials and measuring their corrosion properties. It describes the bone and its structure, types, bone ossification and healing. It defines functions of orthopaedic implants and mentions the types of implants – biodegradable and non-biodegradable. The thesis interprets what corrosion is, what categories of corrosion exist and how does the corrosion influence orthopaedic implants. Preparing the solution of stimulated body fluid and manufacturing samples of different metal combinations (of iron, manganese, phosphorus, magnesium, silver and zinc) is included in this thesis, together with corrosion measurements, microscopic observations, EDAX analysis, metallographic analysis, microhardness testing of samples and pH changes measurements of solutions, and the results are interpreted and explained.

In this work, Slow Strain Rate Test (SSRT) testing, Light Optical Microscopy (LOM) and Scanning Electron Microscopy (SEM) were used to study the effect of micro-structure, corrosive environments and cathodic polarisation on stress corrosion cracking (SCC) of two grades of high strength steels, Type A and Type B. Type A is manufactured by quench and tempered (Q&T) method. Type B, a normalize steel was used as reference. This study also supports electrochemical polarisation resistance method as an effective testing technique for measuring the uniform corrosion rate. SSRT samples were chosen from base metal, weld metal and Heat Affected Zone (HAZ). SSRT tests were performed at room temperature under free corrosion potential and cathodic polarisation using 4 mA/cm2 in 1 wt% and 3.5 wt% NaCl solutions. From the obtained corrosion rate measurements performed in 1 wt% and 3.5 wt% NaCl solutions it was observed that increased chloride concentration and dissolved oxygen content enhanced the uniform corrosion for all tested materials. Moreover, the obtained results from SSRT tests demonstrate that both Q&T and normalized steels were not susceptible to SCC in certain strain rate(1×10-6s-1) in 1 wt% and 3.5 wt% NaCl solutions under free corrosion potential. It was con-firmed by a ductile fracture mode and high reduction in area. The weld metal of Type A with acicular ferrite (AF), pro-eutectoid (PF) and bainite microstructure showed higher susceptibility to hydrogen assisted stress corrosion cracking compared to base metal and HAZ. In addition, typical brittle intergranular cracking with small reduction in area was observed on the fracture surface of the Type A due to hydrogen charging.

Aqueous solutions of organic or inorganic salts are used as secondary refrigerants in indirect refrigeration systems to transport and transfer heat. Water is known for its corrosive character and secondary refrigerants based on aqueous solutions have the same tendency. The least corrosive from the aqueous solutions are glycols and alcohols. Salt solutions, such as chlorides and potassium salts, are much more corrosive. Nevertheless, it is possible to minimize corrosion risks at the beginning stage while designing system. Proper design can significantly help in improving system performance against corrosion. There are several aspects which need to be taken into account while working with secondary refrigerants: design of system, selection of secondary refrigerant, proper corrosion inhibitors, compatible materials used to build the installation and proper preparation of system to operation. While choosing proper materials it is advised to avoid the formation of a galvanic couple to reduce the risk of the most dangerous type of corrosion. Oxygen present in installation is another important factor increasing the rate of corrosion. Even small amounts of oxygen can significantly affect the system lifetime. The methods of cleaning, charging the system with refrigerant, and deaeration procedures are extremely important. The purpose of this thesis work is to present the problems of corrosion occurring in the indirect systems with secondary refrigerants. The thesis describes the mechanism of corrosion and its different types, most commonly used materials in installation, different corrosion inhibitors used to protect system. This thesis also lists the available secondary refrigerants on the market and briefly describes them. Further, it describes the important aspects related with designing, preparing and maintaining of indirect systems. This thesis is giving some clues and shows what should be done in order to reduce risks of corrosion. / Effsys 2 P2 project

Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Includes bibliographical references. / by Ronald George Ballinger. / Sc.D.

No description available.

In this study, the impact of galvanic coupling of magnesium to steel on the corrosion rate, surface morphology, and surface film formation was investigated. In particular, the role of self-corrosion was quantified as previous studies showed discrepancies between model predictions and experimental results that were likely due to significant self-corrosion. This experimental study examined the corrosion of Mg coupled to steel in 5 wt% NaCl at cathode-to-anode area ratios that ranged from 5 to 27. Results showed that self-corrosion was significant and accounted for, on average, one-third of total corrosion. Moreover, self-corrosion varied with time and cathode size, and was accelerated by the high dissolution rate. Film formation was observed on the magnesium surface that inhibited the corrosion rates. This film contained approximately 30% of the Mg lost to corrosion. The morphology of the coupled Mg showed the rapid formation of pits with considerable depth, and was quite distinct from previously studied filiform and disk corrosion for uncoupled Mg. This study demonstrates the important role of self-corrosion during galvanic corrosion of Mg and the need to account for such corrosion when predicting corrosion rates. This study also provides important insight into the processes that control Mg corrosion under several conditions.

The effects of corrosion inhibitors on water quality and the distribution system were studied. This dissertation investigates the effect of inhibitors on iron surface roughness, copper surface roughness, and copper release. Corrosion inhibitors included blended poly/ortho phosphate, sodium orthophosphate, zinc orthophosphate, and sodium silicate. These inhibitors were added to a blend of surface water, groundwater, and desalinated brackish water. Surface roughness of galvanized iron, unlined cast iron, lined cast iron, and polyvinyl chloride was measured using pipe coupons exposed for three months. Roughness of each pipe coupon was measured with an optical surface profiler before and after exposure to inhibitors. For most materials, inhibitor did not have a significant effect on surface roughness; instead, the most significant factor determining the final surface roughness was the initial surface roughness. Coupons with low initial surface roughness tended to have an increase in surface roughness during exposure, and vice versa, implying that surface roughness tended to regress towards an average or equilibrium value. For unlined cast iron, increased alkalinity and increased temperature tended to correspond with increases in surface roughness. Unlined cast iron coupons receiving phosphate inhibitors were more likely to have a significant change in surface roughness, suggesting that phosphate inhibitors affect stability of iron pipe scales. Similar roughness data collected with new copper coupons showed that elevated orthophosphate, alkalinity, and temperature were all factors associated with increased copper surface roughness. The greatest increases in surface roughness were observed with copper coupons receiving phosphate inhibitors. Smaller increases were observed with copper coupons receiving silicate inhibitor or no inhibitor. With phosphate inhibitors, elevated temperature and alkalinity were associated with larger increases in surface roughness and blue-green copper (II) scales.. Otherwise a compact, dull red copper (I) scale was observed. These data suggest that phosphate inhibitor addition corresponds with changes in surface morphology, and surface composition, including the oxidation state of copper solids. The effects of corrosion inhibitors on copper surface chemistry and cuprosolvency were investigated. Most copper scales had X-ray photoelectron spectroscopy binding energies consistent with a mixture of Cu2O, CuO, Cu(OH)2, and other copper (II) salts. Orthophosphate and silica were detected on copper surfaces exposed to each inhibitor. All phosphate and silicate inhibitors reduced copper release relative to the no inhibitor treatments, keeping total copper below the 1.3 mg/L MCLG for all water quality blends. All three kinds of phosphate inhibitors, when added at 1 mg/L as P, corresponded with a 60% reduction in copper release relative to the no inhibitor control. On average, this percent reduction was consistent across varying water quality conditions in all four phases. Similarly when silicate inhibitor was added at 6 mg/L as SiO2, this corresponded with a 25-40% reduction in copper release relative to the no inhibitor control. Hence, on average, for the given inhibitors and doses, phosphate inhibitors provided more predictable control of copper release across changing water quality conditions. A plot of cupric ion concentration versus orthophosphate concentration showed a decrease in copper release consistent with mechanistic control by either cupric phosphate solubility or a diffusion limiting phosphate film. Thermodynamic models were developed to identify feasible controlling solids. For the no inhibitor treatment, Cu(OH)2 provided the closest prediction of copper release. With phosphate inhibitors both Cu(OH)2 and Cu(PO4)·2H2O models provided plausible predictions. Similarly, with silicate inhibitor, the Cu(OH)2 and CuSiO3·H2O models provided plausible predictions.