Goal

 

Nowadays, there are interesting expectations about advanced ceramic composites that incorporate two-dimensional nanomaterials as a second phase, for applications in many fields (aeronautical and aerospace industry, catalysis, energy storage, environmental protection, biotechnology …). The incorporation of these flexible nano-scale nanosheets provides structural ceramics with new mechanisms to resist to crack propagation. This opens the door to the design of novel ceramic composites which combine high fracture toughness together with high resistance to wear, both aspects of special interest for the potential use of these composites in future aerospace braking and propulsion systems.

This draft proposes a systematic study on advanced zirconia composites with either graphene or boron nitride nanosheets, from their manufacture to their microstructural, mechanical and tribological characterization. The aim is to elucidate the mechanisms introduced by these two-dimensional nanostructures to improve the properties of the ceramic matrix. Composites with a tetragonal zirconia matrix doped with 3 mol% yttrium oxide (3YTZP, 3 mol% Yttria Tetragonal Zirconia Polycrystals), with different nanosheet contents will be processed. Special attention will be paid to the dispersion of these nanosheets in the matrix in order to achieve a homogeneous distribution among the ceramic grains, a key aspect to improve the properties of the composites. Sintering will be carried out in an electric discharge furnace (SPS, Spark Plasma Sintering), optimizing the conditions to achieve dense composites and, at the same time, avoiding deterioration of the nanostructures.

The composites’ microstructure (crystalline phases, ceramic grain size, preservation of the nanosheets and their distribution in the matrix, etc.) will be studied in detail by means of X-ray diffraction, Raman spectroscopy and scanning and transmission electron microscopy. From the point of view of the design of new materials for propulsion and braking systems, it is essential to investigate the mechanical properties at room temperature (hardness, fracture toughness and flexural strength) as well as the tribological behavior in aggressive conditions. Therefore, indentation and bending tests will be carried out -at a macro and a microscopic scale- to characterize the mechanical properties. Wear tests as a function of temperature (200-800°C) will be also carried out to establish the framework conditions under which these materials could be used in the different applications considered.

This project is the starting point of an interesting line of research on advanced ceramic composites reinforced with flexible 2D nanostructures for use in the aerospace industry.