Abstract
In this study, the evolution of pores structure in cold-sprayed Ti6Al4V coating (TC4) was analyzed before and after 600-1100 °C heat treatment. It was found that almost no change happened to pores under the heat treatment temperature below 600 °C. When the heat treatment temperature was increased to 700 °C, the coating recrystallized, and pores turned to spheroid and healed because of the “bridging” effect. Some of the pores coarsened after 800 °C and 900 °C heat treatment. This kind of phenomenon grew severer when the heat treatment temperature increased to 1000 °C and 1100 °C. On the whole, with the increment of temperature, for the coating prepared at relatively low temperature, apparent porosity measured by image analysis method tended to go down first and then up, but it decreased all the time for the coating prepared at relatively high temperature. The reason for this phenomenon was contributed to the bonding state of particles in the coating. Only when there were fewer weakly bonded interfaces, the detachment between the particle interfaces which may be caused by release of residual stress did not occur, and there was no pores expansion and internal connectivity, so the porosity continuously decreased.
Highlights
Cold spraying is an emerging thermal spray technology that can accelerate particles to supersonic speed and impact onto a substrate in their solid state [1,2,3]
Sundararajan G et al [22] studied the effect of a post-spray heat treatment at various temperatures on Cu, Ag, Zn, Nb, Ta, Ti, and 316L stainless steels cold sprayed coatings, the results showed that the heat treatment of the cold spray coatings causes a decrease in the extent of inter-splat cracking and porosity in the case of all the coatings
The quasi-in-situ micrograph of as-sprayed five TC4 coatings and the coatings after 600 °C heat treatment was presented in Fig. 1(The spray temperature was showed at the top of the figure, and so were the following figures)
Summary
Cold spraying is an emerging thermal spray technology that can accelerate particles to supersonic speed and impact onto a substrate in their solid state [1,2,3]. The porosity of the cold sprayed Ti or its alloy coatings was reported as 5 %∼25 % depending on the spray conditions, while with a relatively high deposition efficiency (usually>50 %) [19,20]. Garrido et al [24] showed that the porosity of TC4 coating decreased after a solution and precipitation heat treatment at 1000 °Cfor 1 h and 537 °C for 4 h, respectively. Similar results had been observed in cold-Sprayed TC4 after heat treatment [26]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
