Study of Internal and Interfacial Properties of 2D Nanomaterials for Understanding Toughening Mechanisms in Ceramic Nanocomposites

Despite his exceptional properties, such as high hardness, chemical and thermal stability, ceramics have long been recognized by their inherent brittleness. To overcome this challenge, ceramic nanocomposites reinforced with nanotubes or nanoplatelets have emerged as promising materials with enhanced mechanical properties, including improved toughness and strength. Designing and engineering advanced ceramic-based materials with tailored toughness, enable their application in a wide range of industries, including aerospace, energy, and electronics.<br/>The main challenge for these materials is still controlling and optimization of the toughening mechanisms. Most of the reported efforts are primarily associated with tailoring the microstructure and dispersion of the filler and studying the influence of processing parameters (powder processing methods, sintering conditions…) and nanoplatelet nature (loading content, aspect ratio, orientation throughout the ceramic matrix…) on the resulting microstructure and mechanical properties. However, microstructural features like the nanostructure-matrix interface properties, residual stresses, etc are still key aspects that has not been deeply explored.<br/>Studying the role of interfacial bonding between nanoplatelets and ceramic matrices, interlayer spacing in the 2D nanomaterials and even surface functionalization techniques can provide essential knowledge for enhancing the interfacial strength and stress transfer across the composite. However, in this sense there is still a lack of studies on the impact of interfacial properties on the overall mechanical performance of these materials. This work seeks shedding light on the role of the nanoscale interaction for toughening the composites.<br/>Through a simple experimental approach involving a lap shear configuration the interplay between the 2D nanostructures and the ceramic matrix is evaluated. Reduced graphene oxide (rGO) films are attached to Al₂O₃ ceramic substrates using polymer-derived ceramic as an intermediate layer. The lap shear tests are conducted under varying compressive loads to evaluate the influence of mechanical stress on the interfacial performance, friction, and toughening behavior. rGO films of different thicknesses are also considered in order to assess the influence of interlayer sliding on the mechanical behavior of these composites.