Artículos, informes y presentaciones en Congresos
URI permanente para esta colección
Examinar
Examinando Artículos, informes y presentaciones en Congresos por Autor "Bruno, Sonia"
Mostrando 1 - 5 de 5
Resultados por página
Opciones de ordenación
- Documento de conferencia
Acceso Abierto Additives for non-cyanide alkaline zinc electroplating: influence on the properties of the deposits(2012) Egli, Walter Alfredo; Zapponi, Mónica; Bruno, SoniaOver the last decades, one of the most currently used processes for batch zinc electroplating has been the alkaline cyanide process. Due to the environmental and safety problems of cyanides, other alternatives have been developed. Good results have been achieved regarding crystallographic structure and surface appearance on zinc deposits obtained with cyanide-free formulations, both in basic research and industrial processes. Generally, a brightening agent and a leveling agent are used and the joined effect of both additives leads to high quality deposits. Numerous formulations exist in the market and most of them are complex mixtures. In this work leveling agents based in polyethylene glycols of different molecular weights were tested and the influence of the molecular size on the properties of zinc coatings deposited on steel tubes was studied. The additives were characterized by electrochemical techniques. Hull cell tests were performed to study the effect of the additives on high and low current density areas. A rotating cylinder electrode cell was built to simulate industrial conditions and the deposits were characterized by scanning electronic microscopy and X-ray diffraction. The results show how molecular size of leveling agents change zinc crystals structure and how this structure can modify the coatings properties. - Artículo
Acceso Abierto Corrosion of Conductor Rolls in an Electrogalvanizing Line(2012) Egli, Walter Alfredo; Seré, Pablo Ricardo; Bruno, Sonia; Lazzarino, HéctorConductor rolls in continuous cold rolled steel strip horizontal acid electrogalvanizing lines after some period of service suffer a surface deterioration that alters its color, aspect and eventually its roughness what is more deleterious to its good performance. The surface degradation finally produce a pattern on the roll surface that is transferred or copied to the electrogalvanized strip surface originating quality defects that could make some level of rejections in high quality products. This process has been historically thought as an erosion-corrosion one. This work shows some interesting results that help in the understanding of the nature of this specific corrosion mechanism. It is also presented a new method capable of evaluate the corrosion resistance of new materials for construction of conductor rolls for this type of industrial process. Finally a comparison of the corrosion resistance of different alloys using this technique was made. - Documento de conferencia
Acceso Abierto Corrosion of Conductor Rolls in the Electrogalvanizing Line at Sidercolor(2012) Egli, Walter Alfredo; Sere, Pablo Ricardo; Bruno, Sonia; Lazzarino, HéctorAfter some time in service, conductor rolls in the electrogalvanizing line suffer a surface deterioration that has been attributed to a corrosion-erosion process. This process leads to an increase in roughness and finally produces a pattern on the roll surface that is transferred or copied to the electrogalvanized strip surface originating quality defects that lead to rejections in high quality products. To evaluate the conductor rolls in real working condition, a system to determine conductor roll and steel strip electrochemical potentials was designed. An electrochemical experiment that represents in a better way what happens to the conductor roll surface was developed. Different alloys were submitted to this test and then characterized by Scanning electron microscopy (SEM). It was verified that the intensity and the pattern produced by the electrochemical treatment performed in the laboratory and the superficial attack on the discarded conductor roll were almost the same. This work shows some interesting results that help in the understanding of the nature of this specific corrosion mechanism. A method to evaluate the corrosion resistance of new materials for conductor rolls is also presented. Different alloys were evaluated using this technique. - Documento de conferencia
Acceso Abierto Corrosion of conductor rolls in the electrogalvanizing line at Terniun(2013) Egli, Walter Alfredo; Sere, Pablo Ricardo; Bengoa, Leandro N.; Versino, Florencia; Bruno, Sonia; Lazzarino, Andrés; Espósito, FernandoConductor rolls in the electrogalvanizing line are made of Duplex Stainless Steel (DSS) and after some time in service they suffer surface deterioration leading to surface defects and rejections in high quality products. Repassivation kinetics and susceptibility to pitting corrosion for the austenitic and ferritic phases were studied. An electrochemical treatment that reproduces the actual industrial corrosive situation was applied to test different alloys in the laboratory. The Hastelloy C22 showed the best performance and was evaluated in the line during a complete production batch. The new roll presented a slight deterioration, much lower than the DSS rolls. - Artículo
Embargado Influence of organic additives on the behaviour of zinc electroplating from alkaline cyanide-free electrolyte(2017) Pary, Paola; Bengoa, José Fernando; Conconi, María Susana; Bruno, Sonia; Zapponi, Monica; Egli, Walter AlfredoTwo similar polymeric organic compounds from the polyquaternium family were studied as levelling additives in an alkaline cyanide-free zinc plating electrolyte. One additive (LA) has amide bonds between its monomers and the other (LU) has urea unions in its chemical structure. Copper cementation on zinc and gas evolution during aging of the zinc coatings were used to evaluate the effect of the chemical structure of the organic additives on the characteristic deleterious aging process of the coatings when electrodeposited with LA. Scanning electron microscopy and X-ray diffraction were used to follow surface morphology and crystallographic modifications of the coatings during aging. Faster copper cementation kinetics, zinc whiskers growth, blistering of the coating and N2, CH4, CO2and H2evolution were observed during accelerated aging of the coatings when LA was used. The coatings produced with LU did not show any aging effect. These studies show the strong influence that subtle changes in the chemical structure of the organic additive may have on the performance of zinc coating during storage.