Because of the complex microstructure that coated hard materials possess both in terms of substrate and coating, as well as the interrelationship between them, it is necessary to understand the mechanical behaviour at different length scales. In this proposal coated hard materials will be tested using contact loads to measure the response of the material at large length scales, and using micromechanical techniques to test individual phases and constituents of the material, as grains, phases, interfaces and coatings at low length scales. Numerical simulations on the microstructural level will be performed to understand causes of failure and optimize microstructure and deposition processes of coatings. Both AlCrSiN coatings and multilayer AlCrSiN/AlCrON coatings will be tested on cBN and hardmetal substrates, as well as on corroded samples. Contact mechanics will be done by Hertzian tests, with a sphere or a few millimetres pressed against the material of interest. A novel printed electronics approach will be used to monitor the onset of fracture. Small-scale behaviour of coatings and substrates will be measured by nanoindentation and microsamples. These samples will be made by focused ion beam and they will be principally be microcantilevers and micropillars of a few microns in size. This testing will allow to acquire mechanical properties of selected individual microstructural features, such as grains, interfaces or coatings. Main properties to measure will be hardness, Youngs modulus, yield, strength and fracture toughness. With this data, finite element modelling will be performed using realistic meshes obtained after focused ion beam tomography of relevant microstructures. The model will be calibrated against micropillar testing. Afterwards, a constitutive model will be proposed, and calibrated against Hertzian tests. Data will be used to modify the deposition parameters of the coating. In this way, understanding of failure at different length scales as well as prediction of optimal coating/substrate microstructures by modelling will allow enhanced coated hard materials.
Plan Estatal de Investigación Científica y Técnica y de Innovación 2017-2020
Programa Estatal de Generación de Conocimiento y Fortalecimiento Científico y Tecnológico del Sistema de I+D+i
Subprograma Estatal de Generación de Conocimiento
Proyectos de I+D de generación de conocimiento (antigues EXC)