Investigation of RCF failure prewarning of Fe-based coating by online monitoring

Rolling contact fatigue (RCF) tests of plasma sprayed Fe-based coatings were conducted on a ball-on-disc tester. Acoustic emission (AE) technique was used to monitor the whole process of RCF test. The status of AE signals was used as a criterion to calculate the prewarning lifetime. Typical AE response signals for RCF fractures were extracted and the prewarning mechanism was investigated. Results showed that the prewarning lifetime is obviously shorter than RCF failure lifetime. This indicates that AE sensor accurately gives an early alarm before the occurrence of failure. The difference of the prewarning initial lead was due to the different failure mechanism.