Powder requirements for aerosol deposition of alumina films

Exner, Jörg; Hahn, Manuel; Schubert, Michael; Hanft, Dominik; Fuierer, Paul; Moos, Ralf

doi:10.1016/j.apt.2015.05.016

Cited by 59 publications

(27 citation statements)

References 32 publications

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“…[ 41,44 ] Agglomerates can absorb the released impact energy without creating sufficiently fresh surfaces as is necessary for film formation. [ 52 ] A very narrow particle size distribution in the order of one micrometer (depending on the ceramic material) may have a positive effect on the deposition rate due to a reduced abrasive removal process. The coating quality and rate also depends on particle morphology and lattice defects, deposition parameters of the apparatus and internal layer stresses.…”

Section: Resultsmentioning

confidence: 99%

Laser‐Annealing of Thermoelectric CuFe_0.98Sn_0.02O₂ Films Produced by Powder Aerosol Deposition Method

Nazarenus

Kita

Moos

et al. 2020

Adv Materials Inter

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of thermal to electrical energy and vice versa. The state-of-the-art material for thermoelectric generators (TEG) is bismuth telluride (Bi 2 Te 3); however, its application is limited due to its high costs and tendency to oxidize at elevated temperatures. Copper-iron-oxides are a thermally stable promising alternative due to the low costs of the raw materials, their high Seebeck coefficient, and their high electrical conductivity. The PAD method enables to form dense nanocrystalline ceramic films on a variety of substrates with high deposition rates. [16-18] In contrast to all other ceramic processing routes, even moisture-sensitive ceramics, or ceramics with high sintering temperatures can be fabricated at room temperature (RT). [11] Besides the dry ceramic powder, neither additional binders nor other liquids are needed. The ceramic particles are accelerated towards a substrate by a pressure difference. The kinetic energy of the particles is converted into bonding energy during their impact on the substrate and comes along with the reduction of the crystallite size and formation of microstrain within the atomic lattice. [19-21] Particle fracturing occurs along the grain boundaries and within the grains generating temporarily unsaturated surface bonds that cause an excellent adherence of the particles. [22] Despite all the positive aspects of the powder aerosol deposition summarized in Figure 1, a major disadvantage in the as-deposited state that all PAD films have in common is the reduced electrical conductivity of the films. A thermal annealing step is necessary to reduce the mechanical stress of the film and to restore the electrical properties so that they reach bulk values. Exner et al. recently found out that the required annealing temperature in the furnace depends on the melting point of the functional ceramic materials, though it is significantly lower than the typical sintering temperatures. [23] In contrast, laser-based annealing could provide additional advantages like a reduced annealing time or a targeted local property change as it was shown by Palneedi et al. for PZT (Pb(Zr,Ti)O 3) [24-30] and Shinonaga et al. for TiO 2. [31-33] In this study, we investigated the influence of laser irradiation on the properties of a nanocrystalline thermoelectric film. Tin doped copper-iron-oxide respectively copper delafossite (CuFe 0.98 Sn 0.02 O 2), which is known for its good thermoelectric properties and is processability by PAD, [15,34] was synthesized by the mixed-oxide-route. Films were fabricated by powder aerosol deposition method. After deposition, the films were annealed with a frequency tripled Nd:YAG laser (λ = 355 nm) and its influence on the microstructure and the electrical properties was examined by optical and electrical measurements. Powder aerosol deposition (PAD) is a unique coating method that allows the fabrication of dense ceramic films on a variety of substrates at room temperature. This spraying process can produce film thicknesses of several micrometers within minutes without the use of...

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Section: Resultsmentioning

confidence: 99%

Laser‐Annealing of Thermoelectric CuFe_0.98Sn_0.02O₂ Films Produced by Powder Aerosol Deposition Method

Nazarenus

Kita

Moos

et al. 2020

Adv Materials Inter

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“…A custom-made AD apparatus previously reported in [11] was used to produce the GDC10 films. Films with an area of 10 mm × 10 mm were deposited onto ScSZ substrates (scandia-stabilized zirconia, Kerafol Keramische Folien GmbH, Eschenbach, Germany) using a nozzle with an outlet slit-orifice size of 10 mm by 0.5 mm.…”

Section: Methodsmentioning

confidence: 99%

Annealing of Gadolinium-Doped Ceria (GDC) Films Produced by the Aerosol Deposition Method

et al. 2018

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Solid oxide fuel cells need a diffusion barrier layer to protect the zirconia-based electrolyte if a cobalt-containing cathode material like lanthanum strontium cobalt ferrite (LSCF) is used. This protective layer must prevent the direct contact and interdiffusion of both components while still retaining the oxygen ion transport. Gadolinium-doped ceria (GDC) meets these requirements. However, for a favorable cell performance, oxide ion conducting films that are thin yet dense are required. Films with a thickness in the sub-micrometer to micrometer range were produced by the dry room temperature spray-coating technique, aerosol deposition. Since commercially available GDC powders are usually optimized for the sintering of screen printed films or pressed bulk samples, their particle morphology is nanocrystalline with a high surface area that is not suitable for aerosol deposition. Therefore, different thermal and mechanical powder pretreatment procedures were investigated and linked to the morphology and integrity of the sprayed films. Only if a suitable pretreatment was conducted, dense and well-adhering GDC films were deposited. Otherwise, low-strength films were formed. The ionic conductivity of the resulting dense films was characterized by impedance spectroscopy between 300 °C and 1000 °C upon heating and cooling. A mild annealing occurred up to 900 °C during first heating that slightly increased the electric conductivity of GDC films formed by aerosol deposition.

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“…Therefore, the interdigital electrode area of a conductometric device is covered with a thin, dense, and electrically insulating alumina layer, which was deposited by the novel room temperature impact consolidation process (RTIC), also known as aerosol deposition method (ADM) [21][22][23][24]. Compared to the conductometric sensor with the similar electrode geometry, the sensor performance like the blind time could be significantly enhanced.…”

Section: Introductionmentioning

confidence: 99%

Capacitive soot sensor for diesel exhausts

Hagen

Feulner

Werner

et al. 2016

Sensors and Actuators B: Chemical

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Powder requirements for aerosol deposition of alumina films

Cited by 59 publications

References 32 publications

Laser‐Annealing of Thermoelectric CuFe_0.98Sn_0.02O₂ Films Produced by Powder Aerosol Deposition Method

Laser‐Annealing of Thermoelectric CuFe_0.98Sn_0.02O₂ Films Produced by Powder Aerosol Deposition Method

Annealing of Gadolinium-Doped Ceria (GDC) Films Produced by the Aerosol Deposition Method

Capacitive soot sensor for diesel exhausts

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Powder requirements for aerosol deposition of alumina films

Cited by 59 publications

References 32 publications

Laser‐Annealing of Thermoelectric CuFe0.98Sn0.02O2 Films Produced by Powder Aerosol Deposition Method

Laser‐Annealing of Thermoelectric CuFe0.98Sn0.02O2 Films Produced by Powder Aerosol Deposition Method

Annealing of Gadolinium-Doped Ceria (GDC) Films Produced by the Aerosol Deposition Method

Capacitive soot sensor for diesel exhausts

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Laser‐Annealing of Thermoelectric CuFe_0.98Sn_0.02O₂ Films Produced by Powder Aerosol Deposition Method

Laser‐Annealing of Thermoelectric CuFe_0.98Sn_0.02O₂ Films Produced by Powder Aerosol Deposition Method