Fernando Rizzo - Profile on Academia.edu (original) (raw)
Papers by Fernando Rizzo
Evolução do Fórum dos Institutos de Pesquisa do MCTI
Ciência e Sociedade
Materials Science and Engineering: A, 2015
The purpose of this paper is to reveal the dominant factors affecting tensile fracture under a hy... more The purpose of this paper is to reveal the dominant factors affecting tensile fracture under a hydrogen gas atmosphere. Tensile tests were conducted in hydrogen gas with circumferentially-notched specimens of a commercial tempered martensitic steel. Two specimens were exposed to hydrogen gas for 48 h before tensile testing; the other two specimens were not pre-charged. Longitudinal cracks along the loading direction and a transverse crack perpendicular to the loading direction were observed on a cross section of the non-charged specimen, but there was only one small crack on a cross section of the precharged specimen. Electron back scatter diffraction, energy dispersive X-ray spectrometry and finite element method analyses were applied to clarify the relationships among the longitudinal crack, Mn segregation, microstructures of martensitic steel and hydrogen. As a result, it has been demonstrated that Mn segregation and MnS promote hydrogen-assisted cracking in the tempered martensitic steel, causing the longitudinal cracking which is a mechanically non-preferential direction in homogeneous situations. More specifically, we have shown that the role of the Mn segregation is to promote the hydrogen-enhanced decohesion effect (HEDE), which is particularly important for crack propagation in the present case. These considerations indicate that the presence of Mn is crucially important for hydrogen-assisted cracking associated with hydrogen-enhanced localized plasticity (HELP) as well as HEDE.
Microstructural characterization of a 1100 MPa complex-phase steel
Journal of Materials Research and Technology, 2021
Soldagem & Inspeção (Impresso), 2010
Com o objetivo de fornecer subsídios para a seleção de consumíveis para a soldagem molhada foram ... more Com o objetivo de fornecer subsídios para a seleção de consumíveis para a soldagem molhada foram determinadas algumas propriedades do metal de solda a partir de juntas soldadas em água doce com eletrodos revestidos comerciais específicos para este fim. As soldas foram realizadas em tanque a 0,5m de profundidade por dispositivo de soldagem por gravidade. Foram levantados dados que auxiliem a eleger os consumíveis de melhor desempenho para serem testados em maiores profundidades. Foram realizados os seguintes testes e avaliações: caracterização microestrutural, análise e quantificação das inclusões, composição química do metal de solda, dureza Vickers, hidrogênio difusível e avaliação da soldabilidade. Os resultados obtidos permitem classificar os consumíveis testados em dois grupos com características bem distintas. No primeiro grupo está o único eletrodo do tipo oxidante e no segundo grupo estão os quatro eletrodos do tipo rutílico testados. Quanto às propriedades mecânicas e às car...
Facing Global Challenges with Materials Innovation
JOM, 2017
The path of society evolution has long been associated with a growing demand for natural resource... more The path of society evolution has long been associated with a growing demand for natural resources and continuous environmental degradation. During the last decades, this pace has accelerated considerably, despite the general concern with the legacy being left for the next generations. Looking ahead, the predicted growth of the world population, and the improvement of life conditions in most regions, point to an increasing demand for energy generation, resulting in additional pressure on the Earth’s sustainability. Materials have had a key role in decreasing the use of natural resources, by either improving efficiency of existing technologies or enabling the development of radical new ones. The greenhouse effect (CO2 emissions) and the energy crisis are global challenges that can benefit from the development of new materials for the successful implementation of promising technologies and for the imperative replacement of fossil fuels by renewable sources.
Soldagem & Inspeção, 2013
A técnica de soldagem subaquática molhada com eletrodos revestidos apresenta um crescente potenci... more A técnica de soldagem subaquática molhada com eletrodos revestidos apresenta um crescente potencial de aplicação para reparos submarinos em elementos estruturais de unidades flutuantes de produção de petróleo (profundidade até 20 m). Porém, ela apresenta problemas tais como o maior risco de fissuração a frio e de formação acentuada de porosidade. O presente trabalho tem como objetivo melhorar a resistência mecânica do metal de solda de um eletrodo experimental do tipo oxi-rutílico. Foram estudadas as influências de adições de Mo (até 0,4% no metal de solda) na microestrutura e em propriedades mecânicas. As soldas foram realizadas em simulador de soldagem subaquática em profundidade equivalente de 10m utilizando um sistema de soldagem por gravidade. As análises das micrografias mostrou que o aumento do teor de Mo no metal de solda diminui significantemente o tamanho médio de grão da região reaquecida de grãos finos. O aumento do teor de Mo no metal de solda resultou, ainda, em aument...
Materials Research, 2002
The production of bulk Bi 2+x Sr 3-y Ca y Cu 2 O 8+∆ (Bi-2212) superconductors for fault current ... more The production of bulk Bi 2+x Sr 3-y Ca y Cu 2 O 8+∆ (Bi-2212) superconductors for fault current limiter application was developed via a partial-melting route. Aiming high I c (critical current), which is the essential superconducting characteristic for application of this material in the construction of Fault Current Limiters (FCL), the produced blocks have predominance of Bi-2212 phase (83 wt%), which characterizes with high values of zero and onset transport critical temperature of 92 K and 97.5 K, respectively. A relatively low transition width, ∆T, from the superconducting to the normal state of 5.5 K, revealed a good intergrain connectivity. Consequently, current measurements on the blocks of Bi-2212 show promising I c values of 230 A and 850 A for direct and alternate current, respectively. It is expected that further increases in the I c values will depend on the elimination of an observed amorphous phase and further reduction of amount and grain sizes of secondary phases, still present in the blocks obtained by the proposed partial-melting route. This may be achieved by a further optimization of the partial-melting processing parameters.
ABM Proceedings, 2014
Tema: Metalurgia física e comportamento de materiais em temperaturas elevadas
A lei na inovação e a interação universidade empresa
Tecnologia em Metalurgia e Materiais, 2006
O Desafio da Regularidade
Tecnologia em Metalurgia e Materiais, 2005
Revisão por pares implantada pela Comissão Editorial
Tecnologia em Metalurgia e Materiais, 2004
Novo Editor Chefe
Tecnologia em Metalurgia e Materiais, 2007
Um novo desafio
Tecnologia em Metalurgia e Materiais, 2004
The development of cooperative research networks requires the collaboration among partners with d... more The development of cooperative research networks requires the collaboration among partners with different visions about the timing and goals of a research project. In some cases, even competitors are invited to take part in the same initiative, making ground to lack of communication and/or loss of interest in the outcome of the research. During the establishment of the Metal/Mechanics network of the RECOPE program, one large step toward the increase of interaction and collaboration was achieved through one sequence of meetings and short courses on project management and team organization. After these steps had been covered, the strategic planning of the network was carried out, producing a significant improvement in the relationship of the participants. The paper will present examples of benefits resulting from such planning and will highlight the limitations so far observed.
1 Fernando Rizzo, Pontifícia Universidade Católica do Rio de Janeiro, Department of Materials Sci... more 1 Fernando Rizzo, Pontifícia Universidade Católica do Rio de Janeiro, Department of Materials Science and Metallurgy, CP38008, Gávea, Rio de Janeiro, RJ, 22453-900, Brazil, rizzo@dcmm.puc-rio.br Abstract The development of cooperative research networks requires the collaboration among partners with different visions about the timing and goals of a research project. In some cases, even competitors are invited to take part in the same initiative, making ground to lack of communication and/or loss of interest in the outcome of the research. During the establishment of the Metal/Mechanics network of the RECOPE program, one large step toward the increase of interaction and collaboration was achieved through one sequence of meetings and short courses on project management and team organization. After these steps had been covered, the strategic planning of the network was carried out, producing a significant improvement in the relationship of the participants. The paper will present exam...
Estudo Comparativo De Corrosão Em Altas Temperaturas Em Revestimentos De AL2O3 + ALPO4 e AL2O3 No Aço P92
ABM Proceedings
The Corrosion of Fe-15wt% Y and Pure Y and Fe in H2-H2S Mixtures under 10-8 atm S2 at 600-800°C
Materials Science Forum
Microporous and Mesoporous Materials, Apr 1, 2008
Thermal expansion of re-hydrated, Al-containing HZSM-5 was studied by different diffraction techn... more Thermal expansion of re-hydrated, Al-containing HZSM-5 was studied by different diffraction techniques, as well as, through thermogravimetry. It is concluded that the nature of the remarkable shift of thermal expansion properties, that occurs in air, between 350°C and 400°C, where the coefficient of thermal expansion changes from positive to negative is due to dehydration of HZSM-5 and not due to dealumination. The intrinsic thermal expansion properties of dehydrated HZSM-5 are observed in the second cycle of neutron diffraction experiments performed in vacuum ($10 À5 Torr). Near zero thermal expansion was observed in the temperature interval between 100°C and 400°C. These intrinsic thermal properties were rationalized in terms of the rigid unit mode model.
Corrosion Resistance of Thermal Spray Coatings in a Fluid Catalytic Cracking Unit
The oxidation of Co-Nb alloys under low oxygen pressures at 600-800{degrees}C
Oxidation of Metals, Jun 1, 1995
The oxidation of two Co-Nb alloys containing 15 and 30 wt.% Nb has been studied at 600–800° C in ... more The oxidation of two Co-Nb alloys containing 15 and 30 wt.% Nb has been studied at 600–800° C in H2-CO2 mixtures providing an oxygen pressure of 10-24 atm at 600°C and 10-20 atm at 700 and 800°C, below the dissociation pressure of cobalt oxide. At 600 and 700°C both alloys showed only a region of internal oxidation composed, of a
Evolução do Fórum dos Institutos de Pesquisa do MCTI
Ciência e Sociedade
Materials Science and Engineering: A, 2015
The purpose of this paper is to reveal the dominant factors affecting tensile fracture under a hy... more The purpose of this paper is to reveal the dominant factors affecting tensile fracture under a hydrogen gas atmosphere. Tensile tests were conducted in hydrogen gas with circumferentially-notched specimens of a commercial tempered martensitic steel. Two specimens were exposed to hydrogen gas for 48 h before tensile testing; the other two specimens were not pre-charged. Longitudinal cracks along the loading direction and a transverse crack perpendicular to the loading direction were observed on a cross section of the non-charged specimen, but there was only one small crack on a cross section of the precharged specimen. Electron back scatter diffraction, energy dispersive X-ray spectrometry and finite element method analyses were applied to clarify the relationships among the longitudinal crack, Mn segregation, microstructures of martensitic steel and hydrogen. As a result, it has been demonstrated that Mn segregation and MnS promote hydrogen-assisted cracking in the tempered martensitic steel, causing the longitudinal cracking which is a mechanically non-preferential direction in homogeneous situations. More specifically, we have shown that the role of the Mn segregation is to promote the hydrogen-enhanced decohesion effect (HEDE), which is particularly important for crack propagation in the present case. These considerations indicate that the presence of Mn is crucially important for hydrogen-assisted cracking associated with hydrogen-enhanced localized plasticity (HELP) as well as HEDE.
Microstructural characterization of a 1100 MPa complex-phase steel
Journal of Materials Research and Technology, 2021
Soldagem & Inspeção (Impresso), 2010
Com o objetivo de fornecer subsídios para a seleção de consumíveis para a soldagem molhada foram ... more Com o objetivo de fornecer subsídios para a seleção de consumíveis para a soldagem molhada foram determinadas algumas propriedades do metal de solda a partir de juntas soldadas em água doce com eletrodos revestidos comerciais específicos para este fim. As soldas foram realizadas em tanque a 0,5m de profundidade por dispositivo de soldagem por gravidade. Foram levantados dados que auxiliem a eleger os consumíveis de melhor desempenho para serem testados em maiores profundidades. Foram realizados os seguintes testes e avaliações: caracterização microestrutural, análise e quantificação das inclusões, composição química do metal de solda, dureza Vickers, hidrogênio difusível e avaliação da soldabilidade. Os resultados obtidos permitem classificar os consumíveis testados em dois grupos com características bem distintas. No primeiro grupo está o único eletrodo do tipo oxidante e no segundo grupo estão os quatro eletrodos do tipo rutílico testados. Quanto às propriedades mecânicas e às car...
Facing Global Challenges with Materials Innovation
JOM, 2017
The path of society evolution has long been associated with a growing demand for natural resource... more The path of society evolution has long been associated with a growing demand for natural resources and continuous environmental degradation. During the last decades, this pace has accelerated considerably, despite the general concern with the legacy being left for the next generations. Looking ahead, the predicted growth of the world population, and the improvement of life conditions in most regions, point to an increasing demand for energy generation, resulting in additional pressure on the Earth’s sustainability. Materials have had a key role in decreasing the use of natural resources, by either improving efficiency of existing technologies or enabling the development of radical new ones. The greenhouse effect (CO2 emissions) and the energy crisis are global challenges that can benefit from the development of new materials for the successful implementation of promising technologies and for the imperative replacement of fossil fuels by renewable sources.
Soldagem & Inspeção, 2013
A técnica de soldagem subaquática molhada com eletrodos revestidos apresenta um crescente potenci... more A técnica de soldagem subaquática molhada com eletrodos revestidos apresenta um crescente potencial de aplicação para reparos submarinos em elementos estruturais de unidades flutuantes de produção de petróleo (profundidade até 20 m). Porém, ela apresenta problemas tais como o maior risco de fissuração a frio e de formação acentuada de porosidade. O presente trabalho tem como objetivo melhorar a resistência mecânica do metal de solda de um eletrodo experimental do tipo oxi-rutílico. Foram estudadas as influências de adições de Mo (até 0,4% no metal de solda) na microestrutura e em propriedades mecânicas. As soldas foram realizadas em simulador de soldagem subaquática em profundidade equivalente de 10m utilizando um sistema de soldagem por gravidade. As análises das micrografias mostrou que o aumento do teor de Mo no metal de solda diminui significantemente o tamanho médio de grão da região reaquecida de grãos finos. O aumento do teor de Mo no metal de solda resultou, ainda, em aument...
Materials Research, 2002
The production of bulk Bi 2+x Sr 3-y Ca y Cu 2 O 8+∆ (Bi-2212) superconductors for fault current ... more The production of bulk Bi 2+x Sr 3-y Ca y Cu 2 O 8+∆ (Bi-2212) superconductors for fault current limiter application was developed via a partial-melting route. Aiming high I c (critical current), which is the essential superconducting characteristic for application of this material in the construction of Fault Current Limiters (FCL), the produced blocks have predominance of Bi-2212 phase (83 wt%), which characterizes with high values of zero and onset transport critical temperature of 92 K and 97.5 K, respectively. A relatively low transition width, ∆T, from the superconducting to the normal state of 5.5 K, revealed a good intergrain connectivity. Consequently, current measurements on the blocks of Bi-2212 show promising I c values of 230 A and 850 A for direct and alternate current, respectively. It is expected that further increases in the I c values will depend on the elimination of an observed amorphous phase and further reduction of amount and grain sizes of secondary phases, still present in the blocks obtained by the proposed partial-melting route. This may be achieved by a further optimization of the partial-melting processing parameters.
ABM Proceedings, 2014
Tema: Metalurgia física e comportamento de materiais em temperaturas elevadas
A lei na inovação e a interação universidade empresa
Tecnologia em Metalurgia e Materiais, 2006
O Desafio da Regularidade
Tecnologia em Metalurgia e Materiais, 2005
Revisão por pares implantada pela Comissão Editorial
Tecnologia em Metalurgia e Materiais, 2004
Novo Editor Chefe
Tecnologia em Metalurgia e Materiais, 2007
Um novo desafio
Tecnologia em Metalurgia e Materiais, 2004
The development of cooperative research networks requires the collaboration among partners with d... more The development of cooperative research networks requires the collaboration among partners with different visions about the timing and goals of a research project. In some cases, even competitors are invited to take part in the same initiative, making ground to lack of communication and/or loss of interest in the outcome of the research. During the establishment of the Metal/Mechanics network of the RECOPE program, one large step toward the increase of interaction and collaboration was achieved through one sequence of meetings and short courses on project management and team organization. After these steps had been covered, the strategic planning of the network was carried out, producing a significant improvement in the relationship of the participants. The paper will present examples of benefits resulting from such planning and will highlight the limitations so far observed.
1 Fernando Rizzo, Pontifícia Universidade Católica do Rio de Janeiro, Department of Materials Sci... more 1 Fernando Rizzo, Pontifícia Universidade Católica do Rio de Janeiro, Department of Materials Science and Metallurgy, CP38008, Gávea, Rio de Janeiro, RJ, 22453-900, Brazil, rizzo@dcmm.puc-rio.br Abstract The development of cooperative research networks requires the collaboration among partners with different visions about the timing and goals of a research project. In some cases, even competitors are invited to take part in the same initiative, making ground to lack of communication and/or loss of interest in the outcome of the research. During the establishment of the Metal/Mechanics network of the RECOPE program, one large step toward the increase of interaction and collaboration was achieved through one sequence of meetings and short courses on project management and team organization. After these steps had been covered, the strategic planning of the network was carried out, producing a significant improvement in the relationship of the participants. The paper will present exam...
Estudo Comparativo De Corrosão Em Altas Temperaturas Em Revestimentos De AL2O3 + ALPO4 e AL2O3 No Aço P92
ABM Proceedings
The Corrosion of Fe-15wt% Y and Pure Y and Fe in H2-H2S Mixtures under 10-8 atm S2 at 600-800°C
Materials Science Forum
Microporous and Mesoporous Materials, Apr 1, 2008
Thermal expansion of re-hydrated, Al-containing HZSM-5 was studied by different diffraction techn... more Thermal expansion of re-hydrated, Al-containing HZSM-5 was studied by different diffraction techniques, as well as, through thermogravimetry. It is concluded that the nature of the remarkable shift of thermal expansion properties, that occurs in air, between 350°C and 400°C, where the coefficient of thermal expansion changes from positive to negative is due to dehydration of HZSM-5 and not due to dealumination. The intrinsic thermal expansion properties of dehydrated HZSM-5 are observed in the second cycle of neutron diffraction experiments performed in vacuum ($10 À5 Torr). Near zero thermal expansion was observed in the temperature interval between 100°C and 400°C. These intrinsic thermal properties were rationalized in terms of the rigid unit mode model.
Corrosion Resistance of Thermal Spray Coatings in a Fluid Catalytic Cracking Unit
The oxidation of Co-Nb alloys under low oxygen pressures at 600-800{degrees}C
Oxidation of Metals, Jun 1, 1995
The oxidation of two Co-Nb alloys containing 15 and 30 wt.% Nb has been studied at 600–800° C in ... more The oxidation of two Co-Nb alloys containing 15 and 30 wt.% Nb has been studied at 600–800° C in H2-CO2 mixtures providing an oxygen pressure of 10-24 atm at 600°C and 10-20 atm at 700 and 800°C, below the dissociation pressure of cobalt oxide. At 600 and 700°C both alloys showed only a region of internal oxidation composed, of a