Mechanisms on vacuum heat treatment promoting the adhesion strength of thermal sprayed metallic coatings

Monday, May 7, 2018: 9:40 AM
Tampa 2 (Gaylord Palms Resort )
Mr. Guo-Hui Meng , State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, China
Mr. Bang-Yan Zhang , State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, China
Prof. Hong Liu , State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, China
Prof. Tong Xu , State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, China
Prof. Guan-Jun Yang , State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, China
Prof. Cheng-Xin Li , State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, China
Prof. Chang-Jiu Li , State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, China
In this study, the mechanisms of vacuum heat treatment promoting the adhesion strength of thermal sprayed metallic coatings were investigated by using the atmospheric plasma sprayed (APS) CoNiCrAlY coating as an example. The formation of the metallurgical bonding between the coating and substrate, which determined the increasing of the adhesion strength of coatings, was studied by focusing on the effect of the morphological change of oxide film in the coating. The results showed that with the heat treatment time increasing, oxide film formed in the process of coating deposition gradually broke and subsequently shrank into spherical particles. In addition, for the coating treated by vacuum heat treatment, the adhesion strength of the coating was significantly improved. The increasing of the adhesion strength was caused by the formation of the metallurgical bonding between the coating and the substrate. However, the prerequisite for the formation of the metallurgical bonding was that the oxide film had broken during the vacuum heat treatment. In order to explore the essential condition of the breaking and shrinking of the oxide film, a thermodynamic 2-D model based on the thermal grooving theory was developed in this research.
See more of: Characterization and Testing: Mechanical Properties
See more of: Fundamentals / R&D