Water Stuff & Sun are developing a hydrogen battery based on a technology called SFEER’s. The SFEER’s are spherical high-pressure gas storage containers that are the size of a tennis ball. They consist of a carbon fiber-shell that is lined on the inside with a polymer called PA6. The aim of this literature review is to present suitable materials that can be utilized as a coating on the PA6 liner in the SFEER’s to minimize the hydrogen permeability. The metallic coatings that were investigated are compounds based on chromium, boron, alu- minum and titanium. The non-metallic coatings that were investigated are lamellar inorganic components (LIC) in combination with PA6 and modified graphene oxide (GO). The coating methods that were investigated are some different PVD and CVD methods (sputter deposition, plasma enhanced CVD, ALD), electrodeposition and cold spray. The lowest permeability out of all the coatings was observed for alumina, Al2O3. Titanium nitride, TiN, was also found to have very low permeability. Since these two coatings had the lowest permeabilities they were further compared considering other factors. This resulted in alumina being chosen as the final recommendation for coating the SFEER’s. A comparison was also made to find the most suitable coating method for alumina. Cold spray was found to be very promising but if it can not be used the PVD and CVD methods are other potential candidates.

Hydrogen separation membranes could be an enabling technology in a hydrogen economy. A comprehensive microkinetic model for hydrogen permeation was developed to expand the ability to predict hydrogen flux through various potential dense metal (solid and liquid) membrane candidates over a wide range of operating conditions. The molecular steps in the assumed mechanism, i.e., surface adsorption, dissociation, infiltration, and bulk diffusion, are adopted from the literature. The limiting assumptions made normally in the literature models, however, were avoided to develop a more comprehensive and rigorous model while still being computationally accessible. The use of an electric circuit analogy to model the molecular permeation step network allowed individual steps to be analyzed insightfully and in identifying which are rate-limiting steps under various conditions and which may be considered to be at quasi-equilibrium. The model was validated using experimental flux data available in the literature, and involving kinetic and thermodynamic parameters derived from theoretical and experimental sources, for the conventional solid palladium and palladium- silver membranes. In order to extend the model to evaluate the efficacy of a sandwiched liquid metal membrane (SLiMM), a novel membrane under development in this laboratory, the molecular step kinetic and thermodynamic parameters must first be determined. Experimental as well as theoretical work was thus performed to determine these parameters for liquid gallium (Ga) and liquid indium (In), two potential SLiMM candidates. A semi-theoretical approach termed the Pauling Bond Valence-Modified Morse Potential (PBV-MMP) method was used to determine activation energies as well as pre-exponential factors for the steps involved in hydrogen permeation in a liquid metal. Experimentally, absorption isotherms as well as adsorption and diffusion kinetics were measured using a Sieverts apparatus that operates by measuring the pressure difference when a valve is opened between an evacuated sample chamber of known volume and another chamber charged to an initial pressure of hydrogen gas. Based on the hence theoretically and experimentally determined parameters, the microkinetic model was extended to SLiMM and conditions identified when different steps are rate-limiting or at quasi-equilibrium. The model was compared to experimental data for permeation of hydrogen in liquid Ga and liquid In membranes, giving a reasonable first prediction of the hydrogen flux through each metal membrane, and confirming their potential as hydrogen membranes.

No description available.

ABSTRACT Recent global interests in developing hydrogen economy generate substantial research and development for hydrogen production worldwide. Pd membranes are especially suited for high temperature hydrogen separation and membrane reactor applications. Alloying Pd with Ag not only suppresses hydrogen embrittlement, but also increases the permeability of the alloy membrane. The main objective of this work was to carry out fundamental studies to understand the properties of the porous stainless steel (PSS), morphologies of Pd and Ag deposits on PSS, and the structural changes of the membrane layer upon heat treatment. Both coating and diffusion and co-plating techniques were employed in the study. The Pd-Ag membranes that had sandwiched Ag layers suffered from very low selectivity due to the voids formed because of high diffusion rate of Ag. Alloy membranes with high selectivity can be prepared by applying intermediate annealing after each Ag deposition. On the other hand, the homogeneity of the alloy depended very much on the thickness of the deposited layers and annealing temperature and time. A stable co-plating bath was developed to co-plate Pd and Ag simultaneously. Pd-Ag membranes were prepared from co-plating bath using ultrasound to accelerate the plating rate.

Palladium membranes have been identified as the membranes of choice in hydrogen separation and purification processes due to their infinite selectivity to hydrogen when defect free. Despite their potentials in hydrogen processes, palladium membranes pose challenges in terms of cost and embritllement which occurs when palladium comes in contact with hydrogen at temperatures below 573 K. The challenges posed by palladium membranes have encouraged research into nonpalladium based membranes such as Silica and Alumina. This thesis investigates hydrogen permeation and separation in palladium membranes and also the use of nonpalladium membranes, Silica and Alumina membranes in hydrogen permeation. In this study, hydrogen permeation behavior was investigated for 3 types of membranes, Palladium, Silica and Alumina. Thin palladium films were deposited onto a 30 nm porous ceramic alumina support using both conventional and modified electroless plating methods. The hydrogen separation and purification behavior of the membranes were investigated including the effect of annealing at higher temperatures. Gas permeation through Silica and Alumina membranes was investigated for 5 single gases including hydrogen. The Silica and Alumina membranes were fabricated using the dip coating method and their hydrogen permeation behavior of investigated at different coatings. A thin Palladium (Pd1) membrane with a thickness of 2 μm was prepared over porous ceramic alumina support using the electroless plating method and a maximum hydrogen flux of 80.4 cm3 cm-2 min-1 was observed at 873 K and 0.4 bar after annealing the membrane. The hydrogen flux increased to 94.5 cm3 cm-2 min-1 at same temperature and pressure for the Palladium membrane (Pd2) prepared using the modified electroless plating method. The hydrogen flux increased to 98.1 cm3 cm2 min-1 for the palladium/silver (Pd/Ag) membrane prepared using the codeposition electroless plating method and the PdAg membrane avoided the hydrogen embrittlement at low temperature. Hydrogen purity for the membrane was also investigated for a reformate gas mixture and a maximum hydrogen purity of 99.93% was observed at 873 K and 0.4 bar. The hydrogen purity was observed to increase as a result of the addition of sulphur which surpresses the inhibition effect of the carbon monoxide in the reformate gas mixture. The presence of CO and CO2 was observed to lead to an increase of the exponential factor n above 0.5 as a result of the inhibiting effect of these compounds on hydrogen permeation. The value of the exponential factor n depicting the rate limiting step to hydrogen permeation in the palladium and palladium-alloy membranes was also investigated. Deviations from Sievert’s law were observed from the Palladium membranes inverstigated in this work. In single gas hydrogen permeation investigation for the Pd1 membrane prepared using the conventional electroless plating method, the value of the exponential factor n = 0.5 in accordance with Sievert’s law. However, for the mixed gas hydrogen separation investigation n=0.62 at 573 K which decreased to 0.55 when the membrane was annealed at 873 K. For the Pd2 membrane prepared using the modified elctroless plating method, n=1 at 573 K but the value decreased to 0.76 for the mixed gas hydrogen separation investigation at same temperature which depicts a deviation from Sievert’s law. In all the investigations carried out for the Pd3 palladium alloy membrane prepared using the co-deposition Pd/Ag electroless plating method at same conditions with the Pd1 and Pd2 membranes, n=0.5 in accordance with Sievert’s law. For the Nonpalladium based Silica and ceramic Alumina membranes, investigations were carried out for hydrogen permeation and 5 other single gases; He, CO2, CH4, N2 and Ar. For the Silica membranes, a maximum hydrogen permeance of 3.12-7 x 10 mol m-2 s-1 Pa-1 at 573 K and 0.4 bar was observed which increased to 4.05 x 10-7 mol m-2 s-1 Pa-1 at 573 K and 0.4 when the membrane was modified with Boehmite sol prior to deposition of the Silica layer. The permeance for hydrogen and the 5 single gases was investigated for the alumina membrane at 5 successive coatings. It was observed that the commercial alumina membrane displayed a maximum hydrogen permeance of 9.72 x 10-7 mol m-2 s-1 Pa-1 at 573 K and 0.4 bar which increased to 9.85 x 10-7 mol m-2 s-1 Pa-1 at same temperature and pressure when the membrane was modified with Boehmite sol.

Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-08-22T13:32:43Z No. of bitstreams: 1 JULIANA DE FIGUEIREDO LIMA - TESE (PPGEQ) 2018.pdf: 3687514 bytes, checksum: 5500c1ad00c05f03476049218f866f46 (MD5) / Made available in DSpace on 2018-08-22T13:32:43Z (GMT). No. of bitstreams: 1 JULIANA DE FIGUEIREDO LIMA - TESE (PPGEQ) 2018.pdf: 3687514 bytes, checksum: 5500c1ad00c05f03476049218f866f46 (MD5) Previous issue date: 2018-03-02 / Capes / Diante de futuras perspectivas para utilização de ligas com memória de forma (LMF) a base de CuAlNi e devido ao seu baixo custo e relativa facilidade de fabricação, o estudo de corrosão e permeação por hidrogênio nessas ligas é de extrema importância para a comunidade científica e os diferentes setores da indústria. Este trabalho realizou um estudo de corrosão em ligas LMF do tipo CuAlNi e CuAlNi(MnTi) a diferentes temperaturas a partir do seu estado bruto de fusão e tratadas termicamente; foi também investigado a permeação por hidrogênio na LMF CuAlNi comercial e fabricada em laboratório. O estudo de corrosão foi realizado utilizando-se técnicas eletroquímicas de polarização linear para determinação da resistência à polarização (RP), taxa de corrosão (CR) e corrosimetria em diferentes temperaturas e os resultados obtidos foram comparados para as duas ligas utilizadas. Já o estudo de permeação por hidrogênio, foi realizado pelo método galvanostático-potenciostático e a análise dos parâmetros difusividade, solubilidade e fluxo de permeação do hidrogênio na liga CuAlNi, foi realizada em relação as ligas API 5L X60, 80 e ECT P110. A verificação do efeito memória de forma por Calorimetria Diferencial de Varredura (DSC) foi igualmente realizada, bem como os produtos formados pela corrosão na superfície das amostras e composição química utilizando a Microscopia eletrônica de Varredura (MEV) e a Espectroscopia de Energia Dispersiva (EDS), respectivamente. Os resultados mostraram que a taxa de corrosão aumentou com a temperatura para a liga bruta de fusão e tratada termicamente. As ligas tratadas termicamente apresentaram um crescimento contínuo de CR desde o início do ensaio devido ao fato de que o resfriamento rápido a partir de altas temperaturas cria um excesso de vacâncias e tensões na microestrutura que acelera os processos corrosivos. As análises de DSC comprovaram que as amostras apresentaram propriedades de memória de forma. Foi possível comprovar a partir das análises MEV e EDS, os pontos de corrosão e sua composição química respectivamente. Finalmente os resultados de permeação por hidrogênio comprovaram uma maior absorção ou solubilidade nestas ligas quando comparadas com alguns aços da classe API. Indicando à princípio, que estes materiais não são indicados para serem utilizados em ambientes ricos em H2. / In view of the future prospects for the use of CuAl Alloys with shape memory (SMA), and due to its low cost and relative ease of manufacture, the study of corrosion and hydrogen permeation in these alloys is extremely important for the scientific community and the different sectors of the industry. In the first case, its chemical stability is evaluated against corrosive environments, and in the second the susceptibility of damage by the absorbed hydrogen. In this way some limits or expansion of application of these alloys may be known. This work aims to perform a corrosion study on SMA alloys of the CuAlNi and CuAlNi (MnTi) type at different temperatures from their melt state and thermally treated; was also investigated the hydrogen permeation in the CuAlNi LMF. The corrosion study was carried out using linear polarization electrochemical techniques to determine polarization resistance (RP), corrosion rate (CR) and corrosimetry at different temperatures. On the other hand, the hydrogen permeation study by the galvanostatic-potentiostatic method and analysis of the parameters diffusivity, solubility and hydrogen permeation flux in the CuAlNi alloy, was evaluated in relation to API alloys 5L X60, 80 and ECT P110. The SMA properties was evaluated by Differential Scanning Calorimetry (DSC) as well as the verification of the products formed by corrosion was performed using Scanning Electron Microscopy (SEM). The verification of the chemical composition of the alloys was carried out using Dispersive Energy Spectroscopy (DES). The results showed that the corrosion rate increased with the temperature for the raw alloy and heat treated. However it has been found that thermally treated alloys have shown a continuous growth of CR since the start of the test due to the fact that rapid cooling from high temperatures creates an excess of vacancies in the microstructure which accelerates the corrosive processes. The DSC analyzes showed that the samples presented shape memory properties. In addition, it was possible to verify the corrosion points and their chemical composition from the SEM and EDS analyzes. Finally the hydrogen permeation tests were carried out with commercial CuAlNi alloy and prepared in the laboratory. The results showed a higher absorption or solubility of the Hydrogen in these alloys when compared with some API grade steels. This indicates at the outset that these materials are not suitable for use in hydrogen-rich atmospheres.

This thesis describes the metallurgical and environmental factors that influence hydrogen embrittlement of super duplex stainless steels and presents a model to predict the rate at which embrittlement occurs. Super duplex stainless steel has an austenite and ferrite microstructure with an average fraction of each phase of approximately 50%. An investigation was carried out on the metallurgical and environmental factors that influence hydrogen embrittlement of super duplex stainless steels. Tensile specimens of super duplex stainless steel were pre-charged with hydrogen for two weeks in 3.5% NaCl solution at 50º C at a range of applied potentials to simulate the conditions that exist when subsea oilfield components are cathodically protected in seawater. The pre-charged specimens were then tested in a slow strain rate tensile test and their susceptibility to hydrogen embrittlement was assessed by the failure time, reduction in cross-sectional area and examination of the fracture surface. The ferrite and austenite in the duplex microstructures were identified by analysing their Cr, Ni, Mo and N contents in an electron microscope, as these elements partition in different concentrations in the two phases. It was shown that hydrogen embrittlement occurred in the ferrite phase, whereas the austenite failed in a ductile manner. An embrittled region existed around the circumference of each fracture surface and the depth of this embrittlement depended on the hydrogen charging time and the potential at which the charging had been carried out. The depth of embrittlement was shown to correlate with the rate of hydrogen diffusion in the alloy, which was measured electrochemically using hydrogen permeation and galvanostatic methods. A two-dimensional diffusion model was used to calculate the hydrogen distribution profiles for each experimental condition and the model could be employed to provide predictions of expected failure times in stressed engineering components.

O processo de proteção catódica é amplamente utilizada na indústria do petróleo e gás para a prevenção contra a corrosão. Entretanto, devido às reações catódicas induzidas pelo potencial catódico aplicado pode ocorrer a formação de depósito calcário na superfície de componentes protegidos catodicamente em água do mar. Existe certa incerteza na literatura sobre o papel do depósito calcário na absorção de hidrogênio e consequentemente na fragilização pelo hidrogênio. Assim, o presente trabalho visa investigar sua influência a fim de contribuir para o melhor entendimento da participação dessa camada nesse fenômeno. Para isso, foram realizados testes de permeação eletroquímica de hidrogênio, de tração de baixa taxa de deformação (BTD) e de cronoamperometria no aço API 5CT P110 em três soluções diferentes: água do mar sintética (AMS), água do mar sintética sem Ca2+ e Mg2+ e NaCl 3,5%. Além disso, foram aplicados dois potenciais catódicos: -1000 mVECS e -1500 mVECS. Após o ensaio de tração de BTD e de cronoamperometria as amostras foram analisadas em MEV/EDS. A partir dos resultados obtidos verificou-se que o depósito calcário formado em AMS em -1000 mVECS é formado por uma fina camada inicial rica em Mg seguida de cristais de aragonita. A formação dessa camada aparentemente diminuiu o fluxo de hidrogênio no estado estacionário em comparação com as demais soluções avaliadas nesse mesmo potencial. Todavia, essa diminuição não resultou em uma mudança significativa na fragilização do material. O depósito calcário formado em AMS em -1500 mVECS mostrou-se poroso e pulverulento, apresentando principalmente Mg em sua composição. O fluxo de hidrogênio no estado estacionário e a fragilização do material em AMS em -1500 mVECS foi maior do que nas demais soluções nesse potencial. Um possível mecanismo para explicar o efeito do depósito calcário na absorção e na fragilização pelo hidrogênio foi proposto e indica a competição entre o fator superficial ocasionado pela formação do depósito calcário e a sobretensão em hidrogênio. / The process of cathodic protection is widely used in oil & gas industry to corrosion prevention. However, the cathodic reactions induced by the applied cathodic potential can lead to the calcareous deposit formation on the cathodically protected structure surface in sea water. There is uncertainty about the role of calcareous deposit on hydrogen uptake and consequently on hydrogen embrittlement. Hydrogen electrochemical permeations, slow strain rate and chronoamperometric tests were carried out in three different solutions: artificial sea water, artificial sea water without Ca2+ and Mg2+ and 3.5% NaCl solution. Besides that, two cathodic potentials were applied: -1000 mVSCE e -1500 mVSCE. After slow strain rate and chronoamperometric tests the samples were analyzed in SEM/EDS. According to the obtained results it was observed that calcareous deposits formed in artificial sea water at -1000 mVSCE consists on a thin Mg-rich inner layer and an outer layer of aragonite crystals. The deposit formation apparently decreased hydrogen flux at steady state in comparison with other solutions evaluated at the same potential. The calcareous deposit formed in artificial sea water at -1500 mVSCE was porous, powdery and mainly composed by Mg. The hydrogen flux at steady state and the embrittlement of the material were higher in artificial sea water at -1500 mVSCE than in other solutions at the same potential. A possible mechanism to explain the calcareous deposit effect on hydrogen uptake and on hydrogen embrittlement was proposed and it indicates the competition between the surface effect induced by calcareous deposit formation and the hydrogen overpotential.

O processo de proteção catódica é amplamente utilizada na indústria do petróleo e gás para a prevenção contra a corrosão. Entretanto, devido às reações catódicas induzidas pelo potencial catódico aplicado pode ocorrer a formação de depósito calcário na superfície de componentes protegidos catodicamente em água do mar. Existe certa incerteza na literatura sobre o papel do depósito calcário na absorção de hidrogênio e consequentemente na fragilização pelo hidrogênio. Assim, o presente trabalho visa investigar sua influência a fim de contribuir para o melhor entendimento da participação dessa camada nesse fenômeno. Para isso, foram realizados testes de permeação eletroquímica de hidrogênio, de tração de baixa taxa de deformação (BTD) e de cronoamperometria no aço API 5CT P110 em três soluções diferentes: água do mar sintética (AMS), água do mar sintética sem Ca2+ e Mg2+ e NaCl 3,5%. Além disso, foram aplicados dois potenciais catódicos: -1000 mVECS e -1500 mVECS. Após o ensaio de tração de BTD e de cronoamperometria as amostras foram analisadas em MEV/EDS. A partir dos resultados obtidos verificou-se que o depósito calcário formado em AMS em -1000 mVECS é formado por uma fina camada inicial rica em Mg seguida de cristais de aragonita. A formação dessa camada aparentemente diminuiu o fluxo de hidrogênio no estado estacionário em comparação com as demais soluções avaliadas nesse mesmo potencial. Todavia, essa diminuição não resultou em uma mudança significativa na fragilização do material. O depósito calcário formado em AMS em -1500 mVECS mostrou-se poroso e pulverulento, apresentando principalmente Mg em sua composição. O fluxo de hidrogênio no estado estacionário e a fragilização do material em AMS em -1500 mVECS foi maior do que nas demais soluções nesse potencial. Um possível mecanismo para explicar o efeito do depósito calcário na absorção e na fragilização pelo hidrogênio foi proposto e indica a competição entre o fator superficial ocasionado pela formação do depósito calcário e a sobretensão em hidrogênio. / The process of cathodic protection is widely used in oil & gas industry to corrosion prevention. However, the cathodic reactions induced by the applied cathodic potential can lead to the calcareous deposit formation on the cathodically protected structure surface in sea water. There is uncertainty about the role of calcareous deposit on hydrogen uptake and consequently on hydrogen embrittlement. Hydrogen electrochemical permeations, slow strain rate and chronoamperometric tests were carried out in three different solutions: artificial sea water, artificial sea water without Ca2+ and Mg2+ and 3.5% NaCl solution. Besides that, two cathodic potentials were applied: -1000 mVSCE e -1500 mVSCE. After slow strain rate and chronoamperometric tests the samples were analyzed in SEM/EDS. According to the obtained results it was observed that calcareous deposits formed in artificial sea water at -1000 mVSCE consists on a thin Mg-rich inner layer and an outer layer of aragonite crystals. The deposit formation apparently decreased hydrogen flux at steady state in comparison with other solutions evaluated at the same potential. The calcareous deposit formed in artificial sea water at -1500 mVSCE was porous, powdery and mainly composed by Mg. The hydrogen flux at steady state and the embrittlement of the material were higher in artificial sea water at -1500 mVSCE than in other solutions at the same potential. A possible mechanism to explain the calcareous deposit effect on hydrogen uptake and on hydrogen embrittlement was proposed and it indicates the competition between the surface effect induced by calcareous deposit formation and the hydrogen overpotential.

O processo de proteção catódica é amplamente utilizada na indústria do petróleo e gás para a prevenção contra a corrosão. Entretanto, devido às reações catódicas induzidas pelo potencial catódico aplicado pode ocorrer a formação de depósito calcário na superfície de componentes protegidos catodicamente em água do mar. Existe certa incerteza na literatura sobre o papel do depósito calcário na absorção de hidrogênio e consequentemente na fragilização pelo hidrogênio. Assim, o presente trabalho visa investigar sua influência a fim de contribuir para o melhor entendimento da participação dessa camada nesse fenômeno. Para isso, foram realizados testes de permeação eletroquímica de hidrogênio, de tração de baixa taxa de deformação (BTD) e de cronoamperometria no aço API 5CT P110 em três soluções diferentes: água do mar sintética (AMS), água do mar sintética sem Ca2+ e Mg2+ e NaCl 3,5%. Além disso, foram aplicados dois potenciais catódicos: -1000 mVECS e -1500 mVECS. Após o ensaio de tração de BTD e de cronoamperometria as amostras foram analisadas em MEV/EDS. A partir dos resultados obtidos verificou-se que o depósito calcário formado em AMS em -1000 mVECS é formado por uma fina camada inicial rica em Mg seguida de cristais de aragonita. A formação dessa camada aparentemente diminuiu o fluxo de hidrogênio no estado estacionário em comparação com as demais soluções avaliadas nesse mesmo potencial. Todavia, essa diminuição não resultou em uma mudança significativa na fragilização do material. O depósito calcário formado em AMS em -1500 mVECS mostrou-se poroso e pulverulento, apresentando principalmente Mg em sua composição. O fluxo de hidrogênio no estado estacionário e a fragilização do material em AMS em -1500 mVECS foi maior do que nas demais soluções nesse potencial. Um possível mecanismo para explicar o efeito do depósito calcário na absorção e na fragilização pelo hidrogênio foi proposto e indica a competição entre o fator superficial ocasionado pela formação do depósito calcário e a sobretensão em hidrogênio. / The process of cathodic protection is widely used in oil & gas industry to corrosion prevention. However, the cathodic reactions induced by the applied cathodic potential can lead to the calcareous deposit formation on the cathodically protected structure surface in sea water. There is uncertainty about the role of calcareous deposit on hydrogen uptake and consequently on hydrogen embrittlement. Hydrogen electrochemical permeations, slow strain rate and chronoamperometric tests were carried out in three different solutions: artificial sea water, artificial sea water without Ca2+ and Mg2+ and 3.5% NaCl solution. Besides that, two cathodic potentials were applied: -1000 mVSCE e -1500 mVSCE. After slow strain rate and chronoamperometric tests the samples were analyzed in SEM/EDS. According to the obtained results it was observed that calcareous deposits formed in artificial sea water at -1000 mVSCE consists on a thin Mg-rich inner layer and an outer layer of aragonite crystals. The deposit formation apparently decreased hydrogen flux at steady state in comparison with other solutions evaluated at the same potential. The calcareous deposit formed in artificial sea water at -1500 mVSCE was porous, powdery and mainly composed by Mg. The hydrogen flux at steady state and the embrittlement of the material were higher in artificial sea water at -1500 mVSCE than in other solutions at the same potential. A possible mechanism to explain the calcareous deposit effect on hydrogen uptake and on hydrogen embrittlement was proposed and it indicates the competition between the surface effect induced by calcareous deposit formation and the hydrogen overpotential.