Juliano Toniolo | Instituto Federal do Rio Grande do Sul (original) (raw)

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Papers by Juliano Toniolo

Materials Research Bulletin, 2005

The combustion synthesis technique using glycine as fuel and aluminum nitrate as an oxidizer is a... more The combustion synthesis technique using glycine as fuel and aluminum nitrate as an oxidizer is able to produce alumina powders. Thermodynamic modeling of the combustion reaction shows that as the fuel-to-oxidant ratio increases, the amount of gases produced and adiabatic flame temperatures also increases. X-ray diffractions showed the amorphous structure for as-synthesized powder and presence of well-crystallized a-Al 2 O 3 after calcination at 1100 8C during soaking time of 1 h. Alumina's largest measured specific surface area was 15 m 2 /g with BET method and 0.51 glycine-to-nitrate ratio. #

SAE Technical Paper Series, 2006

Characteristics Multi-fuel vehicles demand great interest nowadays. This technology makes it poss... more Characteristics Multi-fuel vehicles demand great interest nowadays. This technology makes it possible for engine to work properly with any ethanol-gasoline mixture or Compressed Natural Gas (CNG). The preexisting spark plugs for either ethanol or gasoline engines have been created based on different functional requirements. On this context, to ensure a better performance in any mixed fuelratio and CNG high compression rate it was necessary to develop a spark plug taking into account the requirements for both cases simultaneously. The purpose of this paper is to enlighten the main technical spark plug features as enhanced thermal elasticity, improved ignition reliability through (Quick Heat™ design) and enhanced service life (less sooting, improved corrosion protection). These features provide considerable advantages for the multi-fuel system like improved idle stability, superior cold start and post-start performance, reduced CO (Carbon Monoxide) and HC (Hydrocarbonate) emissions making this spark plug as an environment-friendly product.

Materials Research Bulletin, 2010

The combustion synthesis technique using glycine and urea as fuels and cobalt nitrate as an oxidi... more The combustion synthesis technique using glycine and urea as fuels and cobalt nitrate as an oxidizer is capable of producing well-crystallized Co3O4, CoO, as well as metallic Co powders. An interpretation based on the thermodynamic viewpoint and the measurement of the combustion temperatures during the reactions occurring for various fuel-to-oxidant ratios was proposed for a study of the nature of

NiO is a candidate material for a variety of potential applications, for example, active optical ... more NiO is a candidate material for a variety of potential applications, for example, active optical filters, antiferromagnetic layers, coloring agents for enamel, pigments, catalysts, cathode materials for alkaline batteries and temperature sensors. The nanocrystalline nickel oxide powders have been synthesized by the combustion technique using glycine as a fuel and nitrate as an oxidizer. This process is being used all over the world recently compared to the others well-known wet-chemical methods. The precursor solution was heated to evaporate water, yielding a viscous liquid. It ignited and underwent self-sustaining combustion, producing an ash composed of the oxide product. The as-synthesized particles have been characterized by X-ray diffraction (XRD), and scanning electron microscopy (SEM). Nanocrystalline nickel oxide was possible to be obtained from fuel-lean ratios. The smallest crystallite size was gotten under fuel-lean (0.09) formulation.

Neste trabalho, foram comparadas a sinterização e densificação de alumina-α obtida pelo método de... more Neste trabalho, foram comparadas a sinterização e densificação de alumina-α obtida pelo método de combustão em solução a partir de sol-gel de Al(NO3)3.9H2O/HNO3/PVA e alumina comercial com elevada área superficial. Os pós foram analisados por Difração de Raios X (DRX) e o tamanho de cristalito determinado pelo método Single-Line. As amostras foram conformadas por prensagem uniaxial (60 MPa) e sinterizadas a 1500°C, durante 120 minutos. A densificação foi acompanhada pelo controle da porosidade do material, avaliada pelo método de Arquimedes e Microscopia Eletrônica de Varredura (MEV). Os resultados indicaram que a alumina obtida por combustão em solução do sol-gel de nitrato de alumínio nanohidratado apresentou cristalitos nanométricos, que influenciaram significativamente na sinterização das amostras estudadas, apresentando um grau de densificação mais elevado, quando comparado ao da alumina comercial. Palavras-chave: alumina, síntese por combustão em solução (SCS), densificação, s...

A síntese por combustão em solução (SCS) é um método utilizado para a preparação de pós altamente... more A síntese por combustão em solução (SCS) é um método utilizado para a preparação de pós altamente puros e homogêneos aplicados na obtenção de pós nanocristalinos, utilizando sais reagentes oxidantes (nitratos metálicos) e reagentes redutores (glicina) (1) . Pesquisas relacionadas à sinterização da alumina demonstram a dificuldade da obtenção de materiais densificados sem o uso de elevadas temperaturas e sem um crescimento excessivo no tamanho dos grãos (2,3) . Neste sentido, o Nb 2 O 5 tem sido utilizado como aditivo para o aprimoramento da densificação da o Al 2 O 3 , diminuindo sua temperatura e tempo de sinterização (4) .

Journal of the European Ceramic Society, 2006

The synthesis of chromium oxides by solution combustion synthesis was investigated. Ammonium dich... more The synthesis of chromium oxides by solution combustion synthesis was investigated. Ammonium dichromate, glycine, urea and ammonium nitrate dissolved in aqueous solution were used as the precursors of the oxides. The effect of different reaction parameters, such as fuel richness, stoichiometry and fuel leanness was evaluated; such parameters were modified by changing the reagents and the fuel/oxidant ratio. Amorphous CrO 3 and crystalline Cr 2 O 3 were synthesized. The results suggest that glycine is a better complexing/combustible agent for ammonium dichromate than urea. Addition of extra ammonium nitrate to stoichiometric compositions improved the specific surface area and reduced the crystallite size. The smallest crystallite size (≈20 nm) of Cr 2 O 3 was obtained with glycine as fuel/complexant agent in fuel-lean mixtures. The highest specific surface area (63 m 2 /g) was observed with urea in fuel-rich mixtures, forming amorphous CrO 3 .

Journal of Materials Science, 2007

This article describes the solution combustion synthesis technique as applicable to iron oxide po... more This article describes the solution combustion synthesis technique as applicable to iron oxide powder production using urea as fuel and ferric nitrate as an oxidizer. It focuses on the thermodynamic modeling of the combustion reaction under different fuel-to-oxidant ratios. X-ray diffraction showed magnetite (Fe 3 O 4 ) and hematite (a-Fe 2 O 3 ) phase formations for the as-synthesized powders. The smallest crystallite size was obtained by stoichiometric chemical reaction. The magnetic properties of the samples are also carefully discussed as superparamagnetic behavior.

Diamond and Related Materials, 2006

Multi-walled carbon nanotubes (MWCNTs) have been grown on 7 nm Ni-coated substrates consisting of... more Multi-walled carbon nanotubes (MWCNTs) have been grown on 7 nm Ni-coated substrates consisting of crystalline silicon covered with a thin layer (10 nm) of TiN, by combining hot-wire chemical vapor deposition (HWCVD) and direct current plasma-enhanced chemical vapor deposition (dc PECVD), at 620 -C. Acetylene (C 2 H 2 ) gas is used as the carbon source and ammonia (NH 3 ) and hydrogen (H 2 ) are used either for dilution or etching. The carbon nanotubes range from 20 to 100 nm in diameter and 0.3 to 5 Am in length, depending on growth conditions: plasma intensity, filament current, pressure, C 2 H 2 , NH 3 , H 2 flow rates, C 2 H 2 /NH 3 and C 2 H 2 /H 2 mass flow ratios. By combining the HWCVD and the dc PECVD processes, uniform growth of oriented MWCNTs was obtained, whereas by using only the HWCVD process, tangled MWCNTs were obtained. By patterning the nickel catalyst, with the use of the HW dc PECVD process, uniform arrays of nanotubes have been grown as well as single free-standing aligned nanotubes, depending on the catalyst patterning (optical lithography or electron-beam lithography). In the latter case, electron field emission from the MWCNTs was obtained with a maximum emission current density of 0.6 A/cm 2 for a field of 16 V/Am.