Use of X-ray Computed Tomography to Investigate Rolling Contact Cracks in Plasma Sprayed Fe–Cr–B–Si Coating
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Rolling contact fatigue (RCF) crack behavior within plasma sprayed coating is investigated. RCF experiments of coatings are conducted under rolling contact. Acoustic emission (AE) is used to monitor the on-line experimental process and detect the initial failure of sprayed coating. Industrial X-ray computed tomography (CT) technique is used to observe the crack within the coating or at coating/substrate interface. The results show that AE energy can accurately response the initiation and propagation of cracks within the coating. More importantly, CT technique exhibits obvious advantage in detecting the small-scale fracture within the coating comparing to other traditional detecting methods. The internal cracks are directly found by CT scanning image. The crack propagation within the coating was also examined under rolling contact, which is primarily caused by the shear stress. The origins of fatigue cracks are caused by the micro-defects. Subsequently, the weak bond between the coating and substrate offers the passageway for crack propagation.
KeywordsInternal crack Sprayed coating Rolling contact X-ray computed tomography
This paper was financially supported by NSFC (Grant No. 51675483, 51705028, 51305397), Foundations (Grant No. GZKF-201411 and EM2015042003).
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