The definition of J-integral of interfacial crack was introduced. The three-point bending tests were carried out to obtain the critical loading values when the interfacial crack initiation occurred between coatings and substrates. The finite element analysis (FEA) was adopted to analyze the stress distribution in the specimens and compute the J-integral of the interfacial crack between LX88A coating and Chinese Q345 steel. The results showed that the average value of critical J-integral is 0.70 N/m, which can be taken as the fracture parameter to evaluate the interfacial fracture behavior for the three-point bending specimens of LX88A coating/Q345 steel system.
The fracture behavior of a ceramic reinforced metal-base coating prepared by high velocity arc spray-ing (HVAS) technology in three-point bending test was studied. Moreover, finite element analysis (FEA) was adopted to analyze the stress distribution in the crack front. It can be found that the crack normal to the interface in the coatings occurred at the location where a fixed moment of force was reached. So the critical moment can be taken as the coating cracking criterion, which was confirmed by FEA results. In addition, the stress levels at three different locations where cracks occurred near the interface are almost the same. The results will provide reference for the design of coatings and the structure integrity evaluation of coating/substrate systems.
