EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

In the last decade, there has been a growing interest on graphene-based nanomaterials (GBNs)/ceramic composites. It has been reported that the incorporation of these fillers into ceramic matrices enhances the mechanical, electrical and thermal properties of the resulting materials. Regarding the mechanical behavior of ceramic materials, direct crack measurement after Vickers indentation tests is typically used as an indirect method for estimating the fracture toughness. However, for GBNs/ceramic composites this method does not provide reliable results so the validity for measuring this property is questioned. Instead, methods such as single-edge notched beam (SENB) are suggested to be more reliable to understand the mechanical behavior of these advanced materials.

In this work, two types of composite powders of 3 mol% yttria tetragonal zirconia (3YTZP) containing graphene nanoplatelets and graphene oxide, have been processed by high energy planetary ball milling to achieve a homogeneous dispersion of the GBN in the ceramic matrix. The composites were consolidated by Spark Plasma Sintering and SENB specimens were machined according to ASTM C1421. Three-point bending tests were performed on the specimens to build the R-Curve of the composites. To detect the presence of anisotropy on the mechanical behavior of these materials, the tests were carried out on two orientations of the samples. Then, the resulting R-Curves were evaluated to accurately understand the crack growth resistance of the materials. The effect of the type of GBM, its content and its orientation respect to the pellet axis was analyzed and discussed.