Elastic properties of silicon nitride ceramics reinforced with graphene nanofillers

From bulk to cellular structures: A review on ceramic/graphene filler composites

“…Additionally, certain flaw tolerance has been described in Al 2 O 3 /rGO composites [15] associated to the R-curve behaviour, which they determined for these composites using an indirect method. 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 11 Relating to the elastic properties, most results indicate a reduction of elastic modulus (E) in composites [13,16,36,43], actually producing a softening effect, in contrast to the high elastic modulus of the graphene monolayer (1TPa) [45], although relatively smaller for the GO monolayer (E0.25 TPa) [46]. Detailed studies by Seiner et al [36,43] using resonant ultrasound spectroscopy (RUS) and computer simulations of the resonance spectrum show a noticeable anisotropy for Si 3 N 4 /graphene composites that grows stronger with the graphene filler content, owing to the preferential alignment of the graphene nanoplateletes and to their own anisotropy as well [47].…”

“…K IC data points appear widely scattered, although a consistent difference emerges by 4 enclosing most of the data pertaining to reduced graphene oxide (rGO) and graphene nanoplatelets (GNP) filler composites separately, as the systems with rGO reinforcements generally realize higher K IC at lower filler fractions. At this point, it should be mentioned that many studies use the Vickers indentation technique (IF) for determining K IC ; but this method is often controversial and raises criticisms about its validity, which keenly depends on the contact-mechanical response of the material; as it has been pointed by Wang et al [35], this is especially critical in the case of anisotropic materials, nanocomposites or ceramics sufficiently weak in shear, as 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 5 considerable redistribution of stresses can take place under the indenter, resulting in the absence of the classical radial cracks [19,36]. In Figure 2 some examples of this phenomenon for Si 3 N 4 and SiC nanocomposites with rGO and GNP fillers are illustrated.…”

“…In Figure 2 some examples of this phenomenon for Si 3 N 4 and SiC nanocomposites with rGO and GNP fillers are illustrated. and Si 3 N 4 /GNP (e) composites, from references [19,36].…”

“…perpendicular to the SPS loading direction. Two types of fillers are considered, rGO sheets and GNP, and different volume fractions indicated by the numbers next to the filler type [36].…”

Reduced Graphene Oxide Reinforced 7075 Al Matrix Composites: Powder Synthesis and Mechanical Properties

“…As the perfect layer structure of two-dimensional (2D) sp2-hybridized carbon atoms, graphene has been extensively investigated in recent years due to its outstanding properties, such as high Young's modulus, high fracture strength, and excellent thermal conductivity [10][11][12][13][14]. Due to these excellent mechanical properties and high specific surface area, graphene is expected to be an ideal reinforcement phase interacting with aluminum matrix, even in a small concentration.…”