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Dive into the research topics where Guilherme Zepon is active.

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Featured researches published by Guilherme Zepon.


Materials Research-ibero-american Journal of Materials | 2013

Microstructure and wear resistance of spray-formed supermartensitic stainless steel

Guilherme Zepon; Claudio Shyinti Kiminami; Walter José Botta Filho; Claudemiro Bolfarini

Since the early 90’s the oil industry has been encouraging the development of corrosion and wear resistant alloys for onshore and offshore pipeline applications. In this context supermartensitic stainless steel was introduced to replace the more expensive duplex stainless steel for tubing applications. Despite the outstanding corrosion resistance of stainless steels, their wear resistance is of concern. Some authors reported obtaining material processed by spray forming, such as ferritic stainless steel, superduplex stainless steel modified with boron, and iron-based amorphous alloys, which presented high wear resistance while maintaining the corrosion performance


Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science | 2016

Solidification Sequence of Spray-Formed Steels

Guilherme Zepon; Nils Ellendt; Volker Uhlenwinkel; Claudemiro Bolfarini

Solidification in spray-forming is still an open discussion in the atomization and deposition area. This paper proposes a solidification model based on the equilibrium solidification path of alloys. The main assumptions of the model are that the deposition zone temperature must be above the alloy’s solidus temperature and that the equilibrium liquid fraction at this temperature is reached, which involves partial remelting and/or redissolution of completely solidified droplets. When the deposition zone is cooled, solidification of the remaining liquid takes place under near equilibrium conditions. Scanning electron microscopy (SEM) and optical microscopy (OM) were used to analyze the microstructures of two different spray-formed steel grades: (1) boron modified supermartensitic stainless steel (SMSS) and (2) D2 tool steel. The microstructures were analyzed to determine the sequence of phase formation during solidification. In both cases, the solidification model proposed was validated.


International Journal of Materials Research | 2012

Mechanochemistry and H-sorption properties of Mg2FeH6-based nanocomposites

Daniel Rodrigo Leiva; Guilherme Zepon; Alexandre Augusto Cesario Asselli; D. Fruchart; S. Miraglia; Tomaz Toshimi Ishikawa; W.J. Botta

Abstract Mg2FeH6 is a promising material for hydrogen storage applications, since it presents the highest known volumetric capacity of 150 kg m−3 of H2 and its metallic constituents are inexpensive. The major drawbacks for its application are the difficulties associated with its synthesis and also its high thermal stability. In this paper, Mg2FeH6-based nanocomposites were prepared from the elements via reactive milling. A high-yield of the complex hydride synthesis was obtained after a systematic processing study, and the best conditions were successfully extended to the mechanochemical synthesis of Mg2CoH5. The influence of different additives such as transition metals, transition metal fluorides and graphite on the H-sorption behavior of the Mg2FeH6-based nanocomposites was evaluated. Mixtures rich in both MgH2 and Mg2FeH6 hydrides present lower temperature ranges of hydrogen release than those which are rich in only one of these hydrides. The MgH2–Mg2FeH6-based nanocomposite presents ultra-fast H-sorption kinetics at 300°C with partial reversible formation of Mg2FeH6.


Archive | 2017

Microstructural Evolution in Spray Forming

Patrick S. Grant; Guilherme Zepon; Nils Ellendt; Volker Uhlenwinkel

Spray forming is a casting process in which the molten metal is directly converted to a solid bulk with unique characteristics. When processed under optimum conditions, spray formed materials typically present microstructures composed of refined polygonal (non-dendritic) grains, uniformly distributed with low levels of micro- and macro-segregation. This set of characteristics is achieved regardless of the alloy system, making spray forming an attractive process to produce alloys where processing by conventional casting techniques is complicated. This chapter is dedicated to presenting the mechanisms that take place when the atomized droplets arrive at the deposit surface, and how the spray-formed microstructures evolve during deposition. It will be seen that spray forming is a self grain-refining casting process and cannot be considered a rapid solidification technique. Section 7.6 will address the main differences between the microstructural evolution in spray forming and other spray deposition or “thermal spray” processes. These processes include plasma spraying, high velocity oxy-fuel, wire arc spraying, detonation gun spraying, etc. In this way, it will show why spray forming is such a unique process. This chapter is also dedicated to presenting how the porosity—an intrinsic feature of spray-formed microstructures—is generated and how the processing parameters affect its type, size and distribution. Furthermore, the generation of other defects related to the solidification and/or to the cooling of the spray formed product after deposition—such as residual stresses and hot cracks—and their influence on the product quality and material properties will be presented. Finally, this chapter will also discuss the effect of the atomization gas (Ar, N2 or He) on the final product quality in terms of porosity and chemical composition of steels, superalloys, and copper alloys.


Archive | 2017

Processing Aspects in Spray Forming

Guilherme Zepon; Nils Ellendt; Volker Uhlenwinkel; H. Henein

Several atomization techniques have been used to spray form a bulk material. Detailed information about those techniques is described in Chapter 2. This chapter focuses on differences in process conditions in spray forming using single fluid and gas atomization as well. Specially, the conditions (e.g. mass flux and enthalpy distribution) in the spray cone of a free fall atomizer are reported in detail. Furthermore, the deposition process is described including topics like overspray, yield, sticking efficiency and temperature history of the deposit. These are important issues with relevance to processes similar to spray forming, such as current thrusts in Additive Manufaturing (AM).


Materials & Design | 2015

Design of wear resistant boron-modified supermartensitic stainless steel by spray forming process

Guilherme Zepon; Alexandre Romão Costa Nascimento; A.H. Kasama; R.P. Nogueira; Claudio Shyinti Kiminami; W.J. Botta; C. Bolfarini


Surface & Coatings Technology | 2016

Wear resistant coatings of boron-modified stainless steels deposited by Plasma Transferred Arc

Erich Sigolo; Juliano Soyama; Guilherme Zepon; Claudio Shyinti Kiminami; W.J. Botta; Claudemiro Bolfarini


International Journal of Hydrogen Energy | 2015

Controlled mechanochemical synthesis and hydrogen desorption mechanisms of nanostructured Mg2CoH5

Guilherme Zepon; Daniel Rodrigo Leiva; M. Kaufman; Santiago Figueroa; Ricardo Floriano; D.G. Lamas; A. A. C. Asselli; W.J. Botta


Journal of Phase Equilibria and Diffusion | 2017

Predicting the Formation of Intermetallic Phases in the Al-Si-Fe System with Mn Additions

Lucas Barcelos Otani; Juliano Soyama; Guilherme Zepon; André Luiz Vasconcellos da Costa e Silva; Claudio Shyinti Kiminami; W.J. Botta; Claudemiro Bolfarini


Journal of Materials Research | 2016

Microstructure formation and abrasive wear resistance of a boron-modified superduplex stainless steel produced by spray forming

Juliano Soyama; Guilherme Zepon; Thiago Pama Lopes; Leamar Beraldo; Claudio Shyinti Kiminami; Walter Jose Botta; Claudemiro Bolfarini

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W.J. Botta

Federal University of São Carlos

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Claudemiro Bolfarini

Federal University of São Carlos

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Claudio Shyinti Kiminami

Federal University of São Carlos

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Daniel Rodrigo Leiva

Federal University of São Carlos

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Juliano Soyama

Federal University of São Carlos

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Thiago Pama Lopes

Federal University of São Carlos

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