Stereolithography additive manufacturing (SL-AM) has been reported to produce SiC ceramic recently. However, both the density and strength of the stereolithography additive manufactured SiC ceramic need to be improved. In this study, different sintering approaches, including liquid phase sintering (LPS), precursor infiltration and pyrolysis (PIP), and liquid silicon infiltration (LSI), were applied based on the SL-AM prepared SiC green bodies. SiC sintered bodies were finally obtained. In each condition, the relative density, crystalline phases, microstructure, and flexural strength were investigated in detail. The relative density of the LPS-sintered SiC, PIP-sintered SiC, and LSI-sintered SiC ceramics were 78.2 ​± ​1.36%, 82.6 ​± ​0.48%, and 96.2 ​± ​0.32%, respectively. And the strength of the LPS-sintered SiC, PIP-sintered SiC, and LSI-sintered SiC body were 77 ​± ​5.2 ​MPa, 184.2 ​± ​8.5 ​MPa, and 210.4 ​± ​10.3 ​MPa, respectively. The density and strength were compared to each other, as well as other additive manufacturing results and traditional results. At last, LSI is found to be the most promising sintering approach for stereolithography additive manufactured SiC ceramic.

Stereolithography additive manufacturing and sintering approaches of SiC ceramics

Enhanced strength and toughness of silicon carbide ceramics by graphene platelet-derived laminated reinforcement

Improvement of toughness of reaction bonded silicon carbide composites reinforced by surface-modified SiC whiskers

The effect of graphene addition on the properties of SiC ceramics—a review

Over the past decade, a new family of ceramic matrix composites has been developed from the incorporation of homogeneously dispersed graphene-based fillers (graphene nanoplatelets/GNP, graphene oxide sheets/rGO or graphene nanoribbons/GNR) into the ceramic matrices. These composites have shown a significant increment of their fracture toughness accompanied by other electrical and thermal functionalities, which make them potentially attractive for a wide range of applications. Here, the main methods for testing the fracture toughness of these composites are described, then the principal observations on the reinforcing mechanisms responsible for this improvement are briefly reviewed, and we discuss the relation with graphene platelets type, morphology and alignment. This article is part of the theme issue 'Nanocracks in nature and industry'.

10 years of research on toughness enhancement of structural ceramics by graphene

To improve the fracture toughness and bending strength of reaction sintering SiC ceramics, graphene oxide (GO) and reduced graphene oxide (rGO) were selected as fillers to develop reinforced SiC ceramic composites by reactive sintering in the current work. Different amounts (0.5, 1.0, 1.5, or 3.0 wt.%) of graphene-reinforced reaction-bonded silicon carbide (RBSC) composites were fabricated. The mechanical behaviors of the materials were evaluated as a function of the type of graphene source and graphene content. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis showed that graphene was maintained after reactive sintering by liquid infiltration of molten silicon. Both the fracture toughness and bending strength of the RBSC increased with employing graphene-based additives. GO showed the most significant positive effects on improving mechanical performance of RBSC ceramics. The highest fracture toughness of 3.6 MPa m1/2 was obtained at 1.5 wt.% of GO addition. It was 33% higher than that of RBSC without graphene. The highest bending strength corresponded to the composite reinforced with GO content of 1.0 wt.%. It was about 58% higher than that of RBSC ceramic. The relation between phase content and mechanical properties was discussed. The main toughening mechanism was sheet pullout/debonding and the distribution of graphene along grain boundaries.

Mechanical properties and microstructure of reaction sintering SiC ceramics reinforced with graphene-based fillers

The invention discloses a preparation method of a graphene composited wooden ceramic material. The method comprises the following steps: 1, mixing materials, namely feeding water, Si powder, C powderand various adhesives at a certain ratio in a ball mill tank for ball milling and mixing to obtain ceramic slurry; and then adding graphene to the ceramic slurry; 2, pouring material and moulding, namely, pouring the mixed composite slurry into a gypsum mould, thus obtaining a biscuit after water in the slurry is absorbed by gypsum; and 3, reacting and sintering, namely, performing liquid Si infiltration on the prepared biscuit through a vacuum carbon tube furnace, thus obtaining the graphene composited wooden ceramic. According to the preparation method, the graphene is oxidized through composition phases of composite ceramic and is pyrolyzed to be reduced in situ during sintering; the graphene oxide is directly introduced into the ceramic slurry, so that the graphene oxide is prevented from agglomerating due to drying, and meanwhile, the problem that the graphene powder is hard to uniformly disperse in the ceramic slurry is solved. The graphene composite wooden ceramic prepared by the method is outstanding in ceramic performances; the graphene is capable of improving and toughening the material, so that the product reliability is improved.

Ma Tian

Papers

Mechanical properties and microstructure of reaction sintering SiC ceramics reinforced with graphene-based fillers

Preparation method of graphene composited SiC wooden ceramic material