**3. Introduction to graphene ceramic composites**

Graphene is an excellent alternative ensuring the availability of composites having remarkable traits. Primarily its exceptional mechanical strength, results in potentially favorable supporting constituents for ceramic composites. Graphene is fascinatedly electrically conductive and this proves its versatility for various applications. Prime challenge for graphene's utility lies in its homogenous implantation into the ceramic matrices. Therefore, to address such challenges major milestone is its processing scheme. Herein the following sections will reveal number of processing schemes as shown in **Figure 3** for graphene based ceramic composites [20].

#### **3.1 Fabrication of graphene/polymer composites**

There are various segments upon the peculiar characteristic of these composites rely on. These includes fine particulates, equiaxed shape ensuring better packing, and homogeneous graphene's distribution into the ceramic matrix. However, another big challenge during investigation of toughening process, has been the fabrication of composites having well supervised micro/nano-structures [21]. Nowadays, appreciations for the sophisticated fabrication process are far more than conventionally adopted powder processing methods. These complex processing techniques comprise, colloidal processing scheme, sol–gel method, and polymer derived ceramic method as shown in **Figure 3**.

#### *3.1.1 Colloidal processing method*

Colloidal processing method exhibits intimate spread of ceramic as well as graphene matrix forming composites. These composites comprise microstructure that are homogenized and having properties ultimately controlled by colloidal chemistry. In colloidal processing technique, graphene is normally covered with ceramic fragments by the colloidal suspensions. This alters its surface chemistry, thereby alleviates repulsion between graphene, causing homogenous spread of graphene into ceramic grains. However, variation in surface chemistry consequences homogenous dispersion, that preserves itself even after sintering. Generally, for the demand of

*Graphene Based Functional Hybrids: Design and Technological Applications DOI: http://dx.doi.org/10.5772/intechopen.108791*

#### **Figure 3.**

*General fabrication routes for graphene ceramic composites (GCCs).*

homogenous spread, both these materials should be dissolved into the same kind of solvent. Although magnetic stirring is another key factor that causes slow mixing and imparts positively for the uniformity in spread of constituents [20].

#### *3.1.2 Sol: gel method*

Sol–gel method comprises a substitute for the supply of dispersion of ceramic as well as graphene composites. Herein, graphene undergoes dispersion through a suitable molecular precursor ((TMOS) tetra methyl ortho-silicate), thereby leading to a condensation process for reinforcement. Homogeneous sol is readily available as the suspension of both the molecular precursor as well as graphene encounters sonication. In general, the method mainly ensures availability of nanocomposites of silica. Although, the technique suits well for fine spread, aggregation for precursor limits its utility [22]. However, sol–gel method need liquid precursors only, thereby providing ease for the processing of well-dispersed composites [23].

## *3.1.3 Molecular level mixing method*

Molecular level mixing scheme encapsulates another way for the production of ceramic and graphene composites. In this method, ceramic salt as well as functionalized graphene is combined in a suitable solvent. This then subjects its conversion to ceramic constituents via proper heat, thereby results in molecular level coating [24]. However, peculiar characteristic of this method includes excellent interface bonding between graphene and ceramic at molecular state. As a result of this strong bonding, a substantial enhance in the properties of the resulting composites becomes easier. Traditional methods of processing graphene-ceramic composites result in fall of mechanical properties. This occurs specifically owing to the effect of aggregation, caused by intermolecular forces [25]. Although, sol–gel method proves to be an excellent candidate for the homogenous dispersion of graphene into the ceramic matrix, however interfacial bonding between graphene and ceramic lacks stability [26].
