Cold Spray Additive Manufacturing of Ti6Al4V: Special Nozzle Design Using Numerical Simulation and Experimental Validation

Abstract

Cold spray additive manufacturing (CSAM) shows great potential in titanium-alloy production as it is a solid-state process. However, data published so far have demonstrated the difficulty of producing dense and high-strength Ti alloy parts. Our previous studies have shown that nozzle design together with high-cost helium propulsive gas plays a crucial role in particle acceleration. In this work, special nozzles for Ti alloy were designed and validated experimentally with commercially available Ti6Al4V powder. Simulation results show that particle impact temperature increases remarkably for a long convergent length, while particle kinetic energy slightly increases, which is validated by experiments. The relationship between the particle impact temperature and practice diameter shows the first increase and then decrease. The experimental results show that as the nozzle convergent section becomes longer, the edges of the single-pass deposits become smoother, and the width, density, deposition efficiency, and microhardness of the single-pass deposits increase.

Numerical Study on Particle Behavior and Deposition Accuracy in Cold Spray Additive Manufacturing

“…On the contrary, some particles do not achieve the critical velocity and they may form weak bonding or simply bounce off the substrate. Therefore, due to circular shape of nozzle crosssection, and since by increasing the radial distance from the nozzle centerline, both the concentration of the particles as well as the number density of high-speed particle decrease, a triangular deposit profile would be formed which has been observed in several studies [18][19][20][21]25,[41][42][43]. all the particles impact on the top surface.…”