Navegando por Autor "Bertelli, Felipe"

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Degradação de tubos de aços ASTM A 249 TP-316L e AISI-316L instalados em reatores para polimerização de PVC.
(2020) Biguetti, Wilson José; Cruz, Clarissa Barros da; Bertelli, Felipe; Feitosa, Emmanuelle Sá Freitas
No processo de produção de resinas de Policloreto de Vinila (PVC) é comum a utilização de equipamentos fabricados em aços inoxidáveis devido à boa resistência à corrosão e excelentes propriedades mecânicas. Trocadores de calor utilizados em reatores para polimerização, sofrem uma exposição contínua a cloretos e ácido clorídrico, neste sentido, nas paredes internas dos tubos do trocador de calor ocorre aderência de produtos de corrosão provenientes da reação de polimerização, produzindo regiões mais susceptíveis à corrosão localizada. O presente trabalho teve como objetivo analisar o desempenho de tubos fabricados em aço inoxidável austenítico ASTM A 249 TP-316L e AISI-316L, empregados em trocadores de calor (TC) e tubos de purga (TP), respectivamente, que operam em meio a cloreto de vinila (VC) contido na reação para a polimerização de PVC.
Interfacial heat transfer and microstructural analyses of a Bi- 5% Sb lead- free alloy solidified against Cu, Ni and low-C steel substrates.
(2021) Lima, Thiago Soares; Cruz, Clarissa Barros da; Xavier, Marcella Gautê Cavalcante; Reyes, Rodrigo André Valenzuela; Bertelli, Felipe; Garcia, Amauri; Spinelli, José Eduardo; Cheung, Noé
Bi-Sb system alloys demonstrate high corrosion resistance and good wettability, becoming promising for use as lead-free solder alloys. The simplicity of the phase diagram is also a characteristic of this system, which is isomorphous forming the (Bi,Sb) phase. While extensive research has been performed on heat flow in couples of microelectronics surfaces with eutectic and peritectic alloys, literature regarding the issues of interfacial heat transfer between isomorphous alloys and microelectronics substrates is nonexistent. In this regard, the present research work demonstrates not only the application of a numerical mathematical model for thermal interface conductance but also wetting and interfacial reaction layer results in the formation of phases for the Bi- 5 wt% Sb alloy in different substrate materials. After carrying out the mentioned analyzes in three different conditions, Bi-Sb/copper, Bi-Sb/nickel and Bi-Sb/low-C steel, the wetting angle is shown not to be the predominant factor in controlling the interfacial heat transfer. Instead, the phases forming the interfacial layer from each of the tested substrates have a role in the heat transfer coefficients (h). In the case of the steel substrate, there is no layer formation, which allows greater contact conductance, whereas Bi-Sb/copper and Bi-Sb/nickel couples generate smaller h, being reasonably similar to each other.
Thermal conductance at Sn‐0.5mass%Al solder alloy/substrate interface as a factor for tailoring cellular/dendritic growth.
(2022) Oliveira Junior, Ricardo; Cruz, Clarissa Barros da; Barros, André dos Santos; Bertelli, Felipe; Spinelli, José Eduardo; Garcia, Amauri; Cheung, Noé
The use of Al for replacing high-cost alloying metals, like Ag, Bi, and Cu, as the second major element in Sn-based alloys, arises as a promising alternative for the development of low-cost Pb-free solder alloys. To date, however, the interfacial characteristics of Sn–Al solder joints in electronic substrates remain barely explored. Thus, the present study focuses on an understanding of the mechanisms afecting the heat transfer efciency between a Sn–Al eutectic alloy and two types of substrates, establishing correlations with the microstructure evolution. Results of solidifcation experiments coupled with mathematical modeling demonstrate an interfacial thermal conductance between the Ni substrate and the Sn-0.5mass%Al alloy higher than that observed for the Sn–Al/Cu couple. Furthermore, Al-rich intermetallics are shown to occur at the interfacial reaction layers for both tested conditions. While dendritic and dendritic/cellular morphologies predominate in the solidifcation of the Sn–Al eutectic alloy in a Cu substrate, the better heat extraction through the Ni substrate induces the growth of refned high-cooling rate cells. Then, growth laws relating the length scale of the Sn-matrix, represented by cellular or primary dendritic spacings, to solidifcation thermal parameters such as cooling rate and growth rate are proposed.