A High-Temperature Reducing Jet Reactor for Flame-Based Metal Nanoparticle Production

Scharmach, William J.; Buchner, Raymond D.; Papavassiliou, Vasilis; Pacouloute, Perry; Swihart, Mark T.

doi:10.1080/02786826.2010.511320

Cited by 24 publications

(19 citation statements)

References 15 publications

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“…Our prototype HTRJ reactor was described in detail by Scharmach et al (2010). It uses oxygen at a flow rate of ∼2.3 standard liters per minute (SLM) and a larger flow of hydrogen and nitrogen (∼14 SLM total) to form an inverted diffusion flame.…”

Section: Materials and Synthesismentioning

confidence: 99%

“…The advantages of HTRJ technology stem from the use of low-cost, water-soluble nitrate precursors and a low-cost energy source in a continuous and environmentally benign process. The flame-based aerosol reactor configuration used to make these nanostructured coatings was developed by Scharmach et al (2010) and is described further below. The key addition to the previously described system was a holder for mounting a 12.5 mm diameter substrate in the aerosol flow, just above the particle formation chamber, as shown in Figure 1.…”

Section: Introductionmentioning

confidence: 99%

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Creating Conductive Copper–Silver Bimetallic Nanostructured Coatings Using a High Temperature Reducing Jet Aerosol Reactor

Sharma

Buchner

Scharmach³

et al. 2013

Aerosol Science and Technology

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We report production of bimetallic nanostructured coppersilver coatings by in situ deposition and sintering of metal nanoparticles produced as an aerosol. The metal nanoparticles themselves have potential applications in printed electronics, catalysis, antibacterial coatings, and heat transfer fluids. In many applications, nanoparticles are dispersed in an ink, which is then printed or coated onto a substrate and converted into a nanostructured thin film. Direct deposition from the aerosol allows us to produce nanostructured thin films without first dispersing the particles in a solvent. The high temperature reducing jet process allows formation of these metal nanoparticles from low-cost metal salt precursors in the gas phase. In this method, a fuel-rich hydrogen flame provides a low-cost source of energy to drive nanoparticle formation in a reducing environment. The aqueous precursor solution is delivered into the hot combustion product gases within a converging-diverging nozzle. The high-speed gas flow atomizes the precursor and provides exceptionally rapid mixing of the precursor with the hot gases. Here, particles are formed, then immediately quenched and deposited on a glass substrate. The effect of the silver content of the mixed copper-silver films on their electrical conductivity was studied systematically, revealing an abrupt transition from low conductivity to high conductivity between 30 wt.% and 40 wt.% silver.

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Section: Materials and Synthesismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Creating Conductive Copper–Silver Bimetallic Nanostructured Coatings Using a High Temperature Reducing Jet Aerosol Reactor

Sharma

Buchner

Scharmach³

et al. 2013

Aerosol Science and Technology

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“…6 It consists of a burner in which a relatively small flow of oxygen (2 SLM) and a larger flow of hydrogen and nitrogen (12 SLM total) support an inverted diffusion flame (oxidant on the inside, fuel on the outside) at the tip of the oxygen inlet lance. The flame temperature is controlled by varying the oxygen flow while always using excess hydrogen.…”

Section: Methodsmentioning

confidence: 99%

“…5 The technique presented here is used in conjunction with the flame-based high-temperature reducing jet aerosol reactor developed by Scharmach et al shown schematically in Figure 1. 6 Carbon coated nanoparticles have been previously reported by several groups, but in contrast to this contribution, the carbon coating in those cases was not intended to encapsulate multiple particles or improve particle collection and handling. Luechinger et al synthesized copper nanoparticles using a bottom up approach with in situ formation of protective shells of graphene to produce air-stable and chemically inert material.…”

Section: Introductionmentioning

confidence: 95%

Amorphous carbon encapsulation of metal aerosol nanoparticles for improved collection and prevention of oxidation

Scharmach¹,

Sharma

Buchner

et al. 2013

AIChE Journal

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A technique to encapsulate silver nanoparticles in an amorphous carbon matrix to facilitate nanoparticle collection and limit nanoparticle oxidation is presented. A carbon source added to the metal salt precursor solution decomposes to generate amorphous carbon, which forms large aggregates that are efficiently collected by filtration. The carbon matrix can be removed by oxidation with hydrogen peroxide without damaging the silver nanoparticles within it. X-ray diffraction showed no evidence of oxidation of encapsulated particles over a two-week period, whereas bare particles showed oxidation after 1 day. Slight oxidation was observed following carbon removal, but no further oxidation was detected over a subsequent two-week period. Carbon encapsulation improves nanoparticle collection efficiency, relative to direct collection of unagglomerated silver nanoparticles with membrane filters. The yield of metal nanoparticles is increased by a factor 1.5 to 3 using this approach. The encapsulating carbon itself forms dendritic nanostructures that may also be of interest.

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“…A dosage of excess of hydrogen should be avoided. Reduction processes could change the composition of ZnO particles as seen in experiments with the formation of copper particles by Scharmach et al (2010). To protect the flame cone against additional oxygen from ambient air or atomizing gas, we used argon as the sheath gas (optimum flow rate was 4 L/min) in combination with nitrogen as the atomizing gas (pressure 0.30 bar).…”

Section: Trace Gas Analysesmentioning

confidence: 99%

Development and Evaluation of a Nanoparticle Generator for Human Inhalation Studies with Airborne Zinc Oxide

Monsé

Monz²,

Dahmann³

et al. 2014

Aerosol Science and Technology

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In the EU there is an increasing need for regulatory agencies to derive health based threshold limits based on human inhalation studies with airborne particles. A necessary prerequisite for such projects is the development of a suitable generator system to produce nanoparticle test aerosols for human whole-body inhalation studies. We decided to use a generator with flame-based heating of aqueous precursor solutions. Validation of the test system was done by generating zinc oxide (ZnO) nanoparticles with minimal contamination of trace gases, i.e., nitric oxides or carbon monoxide that could confound the effects seen in exposed subjects. ZnO was selected based on the uncertainties surrounding its health effects after exposure at the workplace. The generation process of the developed flame generator yields ZnO nanoparticles with monomodal size distribution and very good temporal stability. The maximum target exposure mass concentration of 2 mg/m 3 ZnO, with a resulting median particle diameter of 57 nm, is attainable in our human exposure laboratory. The morphological examination shows typical agglomerates and aggregates formed by high temperature processes. Overall, the performed experiments confirm that a constant exposure can be provided for all subjects at all times.

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A High-Temperature Reducing Jet Reactor for Flame-Based Metal Nanoparticle Production

Cited by 24 publications

References 15 publications

Creating Conductive Copper–Silver Bimetallic Nanostructured Coatings Using a High Temperature Reducing Jet Aerosol Reactor

Creating Conductive Copper–Silver Bimetallic Nanostructured Coatings Using a High Temperature Reducing Jet Aerosol Reactor

Amorphous carbon encapsulation of metal aerosol nanoparticles for improved collection and prevention of oxidation

Development and Evaluation of a Nanoparticle Generator for Human Inhalation Studies with Airborne Zinc Oxide

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