1. CRRC Qingdao Sifang Rolling Stock Co., Ltd., Qingdao 266111, China
2. State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, China
3. Luoyang Ship Material Research Institute, Luoyang 471023, China
The low-temperature material deposition characteristic makes cold spray a potential advanced approach to repair and remanufacture high-strength aluminum alloys of high heat susceptibility. However, the cold sprayed 7xxx high-strength Al alloys usually show low bonding strength, lower hardness and wear resistance as compared to the bulk substrate with same composition. In this work, two hard particles were added to the spray powder to study its effects on microstructure, bonding strength, and friction wear performance of the cold-sprayed 7050Al alloy. Brittle Al2O3 and tough WC-17Co metal ceramic particles with a volume fraction of 30% were added into the 7050Al powder under the same parameter conditions to deposit 7050Al/Al2O3 and 7050Al/WC-17Co composite coatings. The cross-sectional microstructure of the coatings was characterized by SEM. The effect of hard particle additions on the bonding strength of the coating was tested according to ASTM C633 Standard. The friction wear behavior of the coating was studied using ball disc friction-wear tests. The results show that during the deposition, brittle Al2O3 particles could not be deformed, resulting in poor bonding to 7050Al and fracture. However, tough WC-17Co hard alloy particles can be deformed and result in better bonding to 7050Al. The tenon-mortise structure formed by WC-17Co particles at the coating/substrate interface can significantly increase the bonding strength of the 7050Al coating from 34.5 to above 73.2 MPa, while Al2O3 particles have little effect on the bonding strength. Compared with 7050Al substrate, the addition of WC-17Co ceramic particles can improve the wear resistance by more than 8 times, while brittle Al2O3 particles leads to more than 50% reduction in wear resistance.