Abstract
Si3N4/C composites were prepared with carbon black and α-Si3N4 powder by a novel sintering method, i.e. spark plasma sintering. SiC particles formed through reactions between the carbon particles and the SiO2 on the Si3N4 surface. The samples were sintered at 1650 °C for 5 minutes in a nitrogen atmosphere. The microstructure, phase composition, mechanical properties, and dielectric properties of the composites were investigated. The relative densities of the C/Si3N4 composites decreased from 99 to 85% when the carbon black content increased from 0 to 20 wt.-%. Bending strength, hardness and dielectric properties were found to be influenced by the amount of carbon black introduced into the silicon nitride matrix.
Kurzfassung
Funken-Plasma-Sintern von Si3N4/C-Verbundwerkstoffen. In der diesem Beitrag zugrunde liegenden Studie wurden Si3N4/C-Verbundwerkstoffe mit einem Ruß- und einem α-Si3N4-Pulver in einem neuen Sinterprozess, dem sogenannten Funken-Plasma-Sintern, hergestellt. SiC-Partikel formten sich dabei aufgrund von Reaktionen zwischen den Kohlenstoffpartikeln und dem SiO2 auf der Si3N4-Oberfläche. Die Proben wurden bei 1650 °C über 5 min in einer Stickstoffatmosphäre gesintert. Das Gefüge, die Phasenzusammensetzung, die mechanischen und die dielektrischen Eigenschaften wurden untersucht. Die relative Dichte der C/Si3N4-Verbundwerkstoffe nahm von 99% auf 85% ab, wenn der Rußanteil von 0 auf 20 wt.-% gesteigert wurde. Die Biegefestigkeit, die Härte und die dielektrischen Eigenschaften wurden durch den Rußanteil, der in die Silikonnitridmatrix eingebracht wurde, beeinflusst.
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