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The production of agglomerate-free SiO2 particles exhibiting a monomodal distribution of particle sizes of around 300 nm by means of direct laser fuming of micrometric SiO2 powders has been successfully demonstrated. With a 12 kW cw CO2 laser system, a production rate of up to 1 kilogram powder per hour was achieved. Almost ideal spherical amorphous SiO2 particles in a broad particle size distribution between 10 nm and several 100 nm (d50 ≈ 300 nm) were synthesized. Several observations suggest weak agglomeration forces between the particles. A temperature reduction of 200 °C for sintering powder compacts was observed.
Generation of ceramic green bodies in the additive manufacturing by Laser Induced Slip-casting (LIS)
(2016)
For the additive manufacture of large components usually powder-based methods are used. A powder is deposited layer wise by a recoater, then, the component structure is printed to the powder bed or sintered by a laser. In slurry based methods, the slurry is deposited by a doctor blade and dried before the printing of binder or the laser treatment. The new method of laser-induced slip casting is also a slurry-based method and the layers deposited sequential. However the slip is not dried and the structure is written directly by a laser into the suspension. The wall thickness of the ceramic material can be adjusted by the laser spot size and treatment time. The water is evaporated by the laser and a green body is formed locally. Because of its porosity, water is taken from the surrounding suspension and the wall thickness of the green body increases with treatment time. Due to the use of highly filled suspensions, the green body is stable in the ceramic slurry. Large green bodies can be built which have no visible layers in the microstructure.
Generation of ceramic green bodies in the additive manufacturing by Laser Induced Slip-casting (LIS)
(2016)
For the additive manufacture of large components usually powder-based methods are used. A powder is deposited layer wise by a recoater, then, the component structure is printed to the powder bed or sintered by a laser. In slurry based methods, the slurry is deposited by a doctor blade and dried before the printing of binder or the laser treatment. The new method of laser-induced slip casting is also a slurry-based method and the layers deposited sequential. However the slip is not dried and the structure is written directly by a laser into the suspension. The wall thickness of the ceramic material can be adjusted by the laser spot size and treatment time. The water is evaporated by the laser and a green body is formed locally. Because of its porosity, water is taken from the surrounding suspension and the wall thickness of the green body increases with treatment time. Due to the use of highly filled suspensions, the green body is stable in the ceramic slurry. Large green bodies can be built which have no visible layers in the microstructure.
Generation of ceramic green bodies in the additive manufacturing by Laser Induced Slip-casting (LIS)
(2016)
For the additive manufacture of large components usually powder-based methods are used. A powder is deposited layer wise by a recoater, then, the component structure is printed to the powder bed or sintered by a laser. In slurry based methods, the slurry is deposited by a doctor blade and dried before the printing of binder or the laser treatment. The new method of laser-induced slip casting is also a slurry-based method and the layers deposited sequential. However the slip is not dried and the structure is written directly by a laser into the suspension. The wall thickness of the ceramic material can be adjusted by the laser spot size and treatment time. The water is evaporated by the laser and a green body is formed locally. Because of its porosity, water is taken from the surrounding suspension and the wall thickness of the green body increases with treatment time. Due to the use of highly filled suspensions, the green body is stable in the ceramic slurry. Large green bodies can be built which have no visible layers in the microstructure.
Additive manufacturing of alkali-activated materials currently attracts a lot of attention, because of the possibility to produce customized high-performance elements for a range of applications, potentially being more resource-efficient than conventionally produced parts. Here, we describe a new additive manufacturing process for alkali-activated materials that is based on selective laser-heating of lithium aluminate/microsilica slurries. The new process-material combination allows to manufacture elements with complex geometries at high building rates and high accuracy. The process is versatile and transferrable to structures of sizes differing by orders of magnitude. The mechanical strength of the obtained materials was in the range of values reported for conventional metakaolin-based geopolymers, and superior to what has been hitherto reported for alkali-activated materials produced by additive manufacturing. This mechanical performance was obtained despite the fact that the degree of reaction of the lithium aluminate and the microsilica was low, suggesting that significant reactions took place only at the surface of the microsilica particles.