Characteristics and heat treatment of cold-sprayed Al-Sn binary alloy coatings

摘要

In this study, Al-Sn binary alloy coatings were prepared with Al-5wt.%Sn (Al-5Sn) and Al-10wt.%Sn (Al-10Sn) gas atomized powders by low pressure and high-pressure cold spray process. The microstructure and microhardness of the coatings were characterized. The as-sprayed coating were heat treated at 150, 200, 250 and 300℃ for 1 hour, respectively. The effect of heat treatment on microstructure, microhardness and conten of Sn phase of the coatings were investigated. The bonding strength of as-sprayed and heat treated Al-Sn coatings were also studied. The results show that the dense and well-bonded Al-10Sn coating can be deposited by low pressure with helium gas while Al-5Sn coating by high-pressure cold spray with nitrogen gas. The content of Sn for both Al-5Sn and Al-10Sn in as-sprayed coatings are consistent with that in feed stock powders. The coarsening and/or migration of Sn phase in both coatings were observed when the annealing temperature exceeds 200℃. Furthermore, the microhardness of the coatings decreased significantly under the annealing temperature of 250℃. EDAX analysis shows that the heat treatment has no significant effect on content of Sn phase in Al-5Sn coatings. Bonding strength of as-sprayed Al-10Sn coating is slightly higher than that of Al-5Sn coating. Annealing under 200℃ can increase the bonding strength of Al-5Sn coatings.