cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.14321659
title: Obtaining electrolytic copper by the electrodeposition process using a non-cyanide bath and surface electrochemical treatment

description: ABSTRACT The electrodeposition of copper on ferrous and non-ferrous substrates from solutions containing cyanide is one of the most used industrial forms. The deposits obtained by this process are of high quality with low operating cost, unsophisticated equipment and simple pre-treatment in the substrate. However, new cyanide-free electrolytes have emerged to replace cyanide solutions that are toxic and have a great potential to cause environmental and health damage. The objective of this work was to obtain electrodeposited copper (electrolytic Cu) by direct current from an ammonium sulfate and sodium citrate bath; and, evaluate its characteristics with those of commercial electrolytic copper (commercial Cu), as well as analyze two methodologies for preparing the metallic surface for analysis by microscopy. The characterization techniques used were X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Optical Microscopy (MO) and nano hardness, the sample surfaces were prepared by conventional and electrolytic polishing. It was observed that the electrolytically polished samples were very bright and showed the grain contours with greater clarity, the same results were not evidenced by conventional polishing. The copper obtained by the cyanide-free bath showed smaller grain sizes and a greater hardness inside them, when compared to commercial Cu. The diffractogram showed high intensity peaks for the electrolytic Cu in the planes (200) and (111) showing a greater preferential crystallographic orientation in the directions of these planes. Finally, the SEM showed a segregation of a phase in the electrolytic Cu, caused by the electrodeposition and also the shapes of the polygonal grains with globular microcavities of the commercial Cu.
DOI: 10.6084/m9.figshare.14321659.v1
title: Obtaining electrolytic copper by the electrodeposition process using a non-cyanide bath and surface electrochemical treatment

description: ABSTRACT The electrodeposition of copper on ferrous and non-ferrous substrates from solutions containing cyanide is one of the most used industrial forms. The deposits obtained by this process are of high quality with low operating cost, unsophisticated equipment and simple pre-treatment in the substrate. However, new cyanide-free electrolytes have emerged to replace cyanide solutions that are toxic and have a great potential to cause environmental and health damage. The objective of this work was to obtain electrodeposited copper (electrolytic Cu) by direct current from an ammonium sulfate and sodium citrate bath; and, evaluate its characteristics with those of commercial electrolytic copper (commercial Cu), as well as analyze two methodologies for preparing the metallic surface for analysis by microscopy. The characterization techniques used were X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Optical Microscopy (MO) and nano hardness, the sample surfaces were prepared by conventional and electrolytic polishing. It was observed that the electrolytically polished samples were very bright and showed the grain contours with greater clarity, the same results were not evidenced by conventional polishing. The copper obtained by the cyanide-free bath showed smaller grain sizes and a greater hardness inside them, when compared to commercial Cu. The diffractogram showed high intensity peaks for the electrolytic Cu in the planes (200) and (111) showing a greater preferential crystallographic orientation in the directions of these planes. Finally, the SEM showed a segregation of a phase in the electrolytic Cu, caused by the electrodeposition and also the shapes of the polygonal grains with globular microcavities of the commercial Cu.
DOI: 10.6084/m9.figshare.14321661.v1
title: Analysis of heat affected zone in double layer welding using the finite element method

description: ABSTRACT The double layer welding technique uses a controlled deposition method, where the relationship between the thermal inputs from the second layer to the first (E2/E1) must be carefully defined to promote grain refinement in the Heat Affected Zone (HAZ). However, the parameterization of the welding processes for this technique is usually experimental, requiring tests, samples and consumables, demanding time and high cost. A possible solution to this problem is a computational analysis applied to the welding process, making this study to be of great relevance. This work aims an initial study of HAZ behavior in double layer welding using the Finite Element Method (FEM). Experiments were performed to compare and validate the numerical model. In this way, six samples were made, three with a single layer and three with double layer. Three different welding energies were used for the first layer (0.571, 0.428 and 0.342 kJ/mm) and the double of those energies for the second layer (1:2 energy rate). Macrographs of the experimental and numerical results were compared for single and double layer conditions, and HAZ dimensions were measured along the sample cross section. Therefore, it was noted that 1:2 energy rate is sufficient to reach the coarse grain zone of the first layer. In addition, macrographic and HAZ measurements results showed excellent convergence between the experimental and numerical analysis, validating the proposed model.
DOI: 10.6084/m9.figshare.14321661
title: Analysis of heat affected zone in double layer welding using the finite element method

description: ABSTRACT The double layer welding technique uses a controlled deposition method, where the relationship between the thermal inputs from the second layer to the first (E2/E1) must be carefully defined to promote grain refinement in the Heat Affected Zone (HAZ). However, the parameterization of the welding processes for this technique is usually experimental, requiring tests, samples and consumables, demanding time and high cost. A possible solution to this problem is a computational analysis applied to the welding process, making this study to be of great relevance. This work aims an initial study of HAZ behavior in double layer welding using the Finite Element Method (FEM). Experiments were performed to compare and validate the numerical model. In this way, six samples were made, three with a single layer and three with double layer. Three different welding energies were used for the first layer (0.571, 0.428 and 0.342 kJ/mm) and the double of those energies for the second layer (1:2 energy rate). Macrographs of the experimental and numerical results were compared for single and double layer conditions, and HAZ dimensions were measured along the sample cross section. Therefore, it was noted that 1:2 energy rate is sufficient to reach the coarse grain zone of the first layer. In addition, macrographic and HAZ measurements results showed excellent convergence between the experimental and numerical analysis, validating the proposed model.
DOI: 10.6084/m9.figshare.14321662
title: Numerical modeling of riveting process on steam turbines blades

description: ABSTRACT The structural fragility due to the riveting process has been investigated in several components, such as in aeronautical structures. This process affects the reliability of the equipment when subjected to the operation loads. The high-pressure rotor under study operated about 3000 hours after re-pair maintenance of blades until the failure detected. This failure is related to the techniques used in the riveting process of the shroud in the blade, which ended up generating cracks in the radius of tenon blade. Thus, the present study numerically evaluates the mechanical behavior of the riveting process by means of a nonlinear analysis using the finite element method (FEM). For the geometry, under analysis (punch, tenon, and shroud) a 2D configuration with axisymmetric behavior was adopted, using the plane183 element for the components and the contac172 and targe169 elements for the contacts. It was adopted the elastoplastic behavior of the material in order to investigate the residual stresses after the riveting process. The results of the simulation presented good correlation with the blades failures, indicating a stress concentration in the radius of the tenon. The stresses on the tenon radius are about 1200 MPa and 180 MPa for the maximum principal stress and minimum principal stress, respectively. However, future studies using other models, such as fracture mechanics, would be applied in order to avoid failure of the joint when requested during the operating phase.
DOI: 10.6084/m9.figshare.14321662.v1
title: Numerical modeling of riveting process on steam turbines blades

description: ABSTRACT The structural fragility due to the riveting process has been investigated in several components, such as in aeronautical structures. This process affects the reliability of the equipment when subjected to the operation loads. The high-pressure rotor under study operated about 3000 hours after re-pair maintenance of blades until the failure detected. This failure is related to the techniques used in the riveting process of the shroud in the blade, which ended up generating cracks in the radius of tenon blade. Thus, the present study numerically evaluates the mechanical behavior of the riveting process by means of a nonlinear analysis using the finite element method (FEM). For the geometry, under analysis (punch, tenon, and shroud) a 2D configuration with axisymmetric behavior was adopted, using the plane183 element for the components and the contac172 and targe169 elements for the contacts. It was adopted the elastoplastic behavior of the material in order to investigate the residual stresses after the riveting process. The results of the simulation presented good correlation with the blades failures, indicating a stress concentration in the radius of the tenon. The stresses on the tenon radius are about 1200 MPa and 180 MPa for the maximum principal stress and minimum principal stress, respectively. However, future studies using other models, such as fracture mechanics, would be applied in order to avoid failure of the joint when requested during the operating phase.
DOI: 10.6084/m9.figshare.14321664
title: Corrosion of galvanic pairs of Co-Cr alloys with high-copper silver amalgam using Mansfeld formulas

description: ABSTRACT In the restoration of lost or damaged dental pieces, different alloys are frequently used, leaving the mouth exposed to electrical currents that circulate through saliva and dental fluids. In the present work, electrochemical methods are used to determine the corrosion rate of galvanic pairs of a high copper silver amalgam with Co-Cr dental alloys in artificial saliva. It is observed that when the difference in corrosion potentials of dissimilar alloys are small (less than 100 mVecs), Evans diagrams do not give good results, so the Mansfeld correction formulas must be used. Thus, it is found that the most resistant to corrosion is the pair formed between the amalgam and the bulk Co-Cr alloy (PG1,3) and that the corrosion products released in greater quantity to the electrolyte are those that contain ions of Co, Cr, Ag, Sr and Cu.
DOI: 10.6084/m9.figshare.14321664.v1
title: Corrosion of galvanic pairs of Co-Cr alloys with high-copper silver amalgam using Mansfeld formulas

description: ABSTRACT In the restoration of lost or damaged dental pieces, different alloys are frequently used, leaving the mouth exposed to electrical currents that circulate through saliva and dental fluids. In the present work, electrochemical methods are used to determine the corrosion rate of galvanic pairs of a high copper silver amalgam with Co-Cr dental alloys in artificial saliva. It is observed that when the difference in corrosion potentials of dissimilar alloys are small (less than 100 mVecs), Evans diagrams do not give good results, so the Mansfeld correction formulas must be used. Thus, it is found that the most resistant to corrosion is the pair formed between the amalgam and the bulk Co-Cr alloy (PG1,3) and that the corrosion products released in greater quantity to the electrolyte are those that contain ions of Co, Cr, Ag, Sr and Cu.
DOI: 10.6084/m9.figshare.14321667
title: The influence of soluble salts content on the performance of an epoxy coating system via accelerated corrosion tests

description: ABSTRACT It is generally accepted that surpassing a threshold value of water-soluble salts at the substrate/coating interface can impart premature failure in painted structures. The Coatings industry has an identified need in defining a maximum allowable soluble salts content, however, a variety of threshold values are found in published data. Based on that, this work aims at evaluate the effect on epoxy coating performance of three different ranges of soluble salts content taking into account the maximum allowable values specified by NORSOK M-501 and IMO PSPC MSC.215, two important standards of naval and offshore sectors. Blast-cleaned carbon steel specimens contaminated with sodium chloride solutions diluted in methanol ranging 20, 50 and 100 mg/m² NaCl were painted with two epoxy-amine paint coats. Samples were evaluated by cathodic disbondment, water immersion at 40 ºC, pull-off adhesion strength and cyclic corrosion tests. Larger blisters and loss of adhesion were observed as the soluble salts content at the interface increased. Although, it was not possible to find a critical level of soluble salts even considering data about similar coating systems. A safe soluble salt content must be chosen based on tests that closer reproduce service and environmental conditions to which a painted structure will be exposed.
DOI: 10.6084/m9.figshare.14321667.v1
title: The influence of soluble salts content on the performance of an epoxy coating system via accelerated corrosion tests

description: ABSTRACT It is generally accepted that surpassing a threshold value of water-soluble salts at the substrate/coating interface can impart premature failure in painted structures. The Coatings industry has an identified need in defining a maximum allowable soluble salts content, however, a variety of threshold values are found in published data. Based on that, this work aims at evaluate the effect on epoxy coating performance of three different ranges of soluble salts content taking into account the maximum allowable values specified by NORSOK M-501 and IMO PSPC MSC.215, two important standards of naval and offshore sectors. Blast-cleaned carbon steel specimens contaminated with sodium chloride solutions diluted in methanol ranging 20, 50 and 100 mg/m² NaCl were painted with two epoxy-amine paint coats. Samples were evaluated by cathodic disbondment, water immersion at 40 ºC, pull-off adhesion strength and cyclic corrosion tests. Larger blisters and loss of adhesion were observed as the soluble salts content at the interface increased. Although, it was not possible to find a critical level of soluble salts even considering data about similar coating systems. A safe soluble salt content must be chosen based on tests that closer reproduce service and environmental conditions to which a painted structure will be exposed.
DOI: 10.6084/m9.figshare.14321668.v1
title: Performance of high strength steel weld metal for welding of mooring components

description: ABSTRACT The present work show the results of an extensive working program whose the main goal is the development of consumables suitable for welding of mooring components manufactured in high strength steels. After an exhaustive evaluation of different chemical compositions, based on a balance of Mn and Ni, a detailed analysis of the mechanical and microstructural properties is done for the heat which proposed the best results in order to allow a decisive conclusion. Welded joints were produced by using 4,0 mm diameter covered electrodes, with preheat of 200 ºC, direct current, flat position and nominal heat input of 1.5 kJ/mm. After welding, mechanical tests (tension, impact Charpy-V, hardness) and metallographic examination (optical microscopy and scanning electron microscopy, electron back scattering diffraction) were performed in specimens removed integrally from the weld metal both in the as welded condition and post weld heat treatment at 600 º C. The results show that the weld metals obtained satisfactory mechanical properties after PWHT, being adequate for application on high strength steel mooring components with several grades according to the IACS W22 specification. In addition, it was noted that impact Charpy-V results were improved with increasing the time of PWHT, which is crucial for larger components.
DOI: 10.6084/m9.figshare.14321668
title: Performance of high strength steel weld metal for welding of mooring components

description: ABSTRACT The present work show the results of an extensive working program whose the main goal is the development of consumables suitable for welding of mooring components manufactured in high strength steels. After an exhaustive evaluation of different chemical compositions, based on a balance of Mn and Ni, a detailed analysis of the mechanical and microstructural properties is done for the heat which proposed the best results in order to allow a decisive conclusion. Welded joints were produced by using 4,0 mm diameter covered electrodes, with preheat of 200 ºC, direct current, flat position and nominal heat input of 1.5 kJ/mm. After welding, mechanical tests (tension, impact Charpy-V, hardness) and metallographic examination (optical microscopy and scanning electron microscopy, electron back scattering diffraction) were performed in specimens removed integrally from the weld metal both in the as welded condition and post weld heat treatment at 600 º C. The results show that the weld metals obtained satisfactory mechanical properties after PWHT, being adequate for application on high strength steel mooring components with several grades according to the IACS W22 specification. In addition, it was noted that impact Charpy-V results were improved with increasing the time of PWHT, which is crucial for larger components.
DOI: 10.6084/m9.figshare.14321671
title: Development and characterization of Ni and Ni-Graphene coatings obtained by electrodeposition on API 5L X80 steel

description: ABSTRACT The aim of the present work was to develop and characterize nanocomposite coatings of Ni and Ni-Graphene applied on API 5L X80 steel surface, using the electrodeposition process, to obtain better anticorrosive properties. Test specimens of dimensions of 20x20x3 mm were submitted to metallographic cleaning and preparation, for later deposition of the coatings. For the electrodeposition process, a nickel-based bath containing sodium dodecyl sulfate (SDS) was used as the surfactant. To obtain the Ni-Graphene coatings, graphene particles (0.2 g/L) were added to the electrolytic bath. The electrodeposits obtained were characterized by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The insertion of graphene to the coating promoted the formation of deposits with more refined grains, and with a well-defined crystal growth direction. Deposits with overlapping lamellar structures were observed and associated to the graphene incorporated into the Ni matrix. The deposition of graphene influenced the preferential orientation of the grains during the electrodeposition process, with the plane (200) being identified as the preferred orientation for the Ni-Graphene nanocomposite. The Ni-Graphene coating obtained better corrosion performance in comparing to the coating of pure Ni and the base metal, presenting a higher corrosion potential value (Ecorr), lower corrosion current density (icorr) value and higher impedance modulus (|Z|).
DOI: 10.6084/m9.figshare.14321671.v1
title: Development and characterization of Ni and Ni-Graphene coatings obtained by electrodeposition on API 5L X80 steel

description: ABSTRACT The aim of the present work was to develop and characterize nanocomposite coatings of Ni and Ni-Graphene applied on API 5L X80 steel surface, using the electrodeposition process, to obtain better anticorrosive properties. Test specimens of dimensions of 20x20x3 mm were submitted to metallographic cleaning and preparation, for later deposition of the coatings. For the electrodeposition process, a nickel-based bath containing sodium dodecyl sulfate (SDS) was used as the surfactant. To obtain the Ni-Graphene coatings, graphene particles (0.2 g/L) were added to the electrolytic bath. The electrodeposits obtained were characterized by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The insertion of graphene to the coating promoted the formation of deposits with more refined grains, and with a well-defined crystal growth direction. Deposits with overlapping lamellar structures were observed and associated to the graphene incorporated into the Ni matrix. The deposition of graphene influenced the preferential orientation of the grains during the electrodeposition process, with the plane (200) being identified as the preferred orientation for the Ni-Graphene nanocomposite. The Ni-Graphene coating obtained better corrosion performance in comparing to the coating of pure Ni and the base metal, presenting a higher corrosion potential value (Ecorr), lower corrosion current density (icorr) value and higher impedance modulus (|Z|).
DOI: 10.6084/m9.figshare.14321670
title: Influence of welding parameters on the geometric and microstructural characteristics of Inconel 625 coatings deposited on ASTM A36 Steel by Plasma Transferred Arc

description: ABSTRACT This work aims to evaluate the influence of welding parameters, current intensity and deposition speed, on the bead geometry, dilution, morphology and properties of a nickel-based alloy coating. For this, single beads of Inconel 625 alloy were deposited on the substrate of ASTM A36 Steel, by PTA-P process. The samples were sandblasted and polished. The samples were chemically etched by a solution of 92 mL HCl, 3 mL HNO3 and 5 mL H2SO4 for 5 minutes. The geometry of the beads (reinforcement height, bead width, penetration and contact angle) was measured through the digital stereoscope microscope. The microstructures of the cross sections were evaluated by optical microscopy and scanning electron microscopy (SEM), to identify the possible presence of precipitated phases in the ferrite matrix. The chemical composition of these present phases, as well as the diffused iron content from the substrate for the coating, were measured by EDX. The type of the phases precipitated by x-ray diffraction in the top samples of the coating were also evaluated, in 1.5 mm height of reinforcement. For mechanical property analysis, the microhardness of the coatings was measured by Vickers microhardness test to evaluate their relationship with the iron present in the coatings, which diffused from the substrate. The results confirmed the influence of welding parameters on coating dilution - Current is the parameter of greatest response. The morphologies of the coatings were presented as a γ matrix with second phase precipitation composed of Ni, Nb, Cr and Mo. The concentration of these precipitations decreased with increasing dilution. This occurred because of the increased migration of Fe present in the substrate of the coating through the diffusion phenomena, with increasing dilution. The Fe reduced the solubility of Nb and Mo of the γ matrix, causing the decrease of its hardness.