Applied Surface Science, Vol.422, 997-1006, 2017
Experimental and numerical investigation of buckling and delamination of Ti/TiN coatings on depleted uranium under compression
The cracking evolution and failure mechanisms of Ti/TiN coatings on depleted uranium (DU) deposited by high power impulse magnetron sputtering were investigated by combing a compression-to-fail test and a numerical fracture modeling technique. The coating buckling and interface delamination were induced by unaxial compression tests, meanwhile the cracking pattern and the buckling characteristics were tracked and measured by an optical microscope (OM). A three dimensional (3D) cohesive fracture model considering both detailed coating cracking and interface cracking was developed to analyse the coating failure mechanism and to evaluate the interfacial adhesive properties. Our simulation results agree well with experiments. It is found that the coupled interacting of ridge crack and a pair of fringe cracks in coatings lead to a spontaneous self-replication propagation for the buckle; mode I fracture played a dominant role in the initiation and propagation of the ridge crack and fringe cracks; the top, the tails and the remained part of the curved interface crack front experienced pure mode I, pure mode II and mixed mode fracture, respectively. The interfacial adhesive strength of Ti/TiN coatings on DU was in the range of 80-100 Mpa, and the critical interfacial adhesive energy was in the range of 2-3 J/m(2). (C) 2017 Elsevier B.V. All rights reserved.