Effects of Process Parameters on the Accuracy of Directed Energy Deposition-Arc Lattice Structures

Curved-generatrix-shell pyramid lattice structures (CPLSs) serve as critical components for hypersonic vehicle thermal protection systems. They can be used to improve thermal insulation performance and reduce the weight of the aircraft. Directed energy deposition-arc fabrication can be used as an effective method to fabricate CPLS. In this study, the effects of process parameters on droplet transfer, spreading, and rod formation accuracy were studied. With small current deposition, the droplet underwent a short-circuit transition, and the rod was well formed. When a large current was deposited, the droplet underwent spray transfer, and rod formation was poor. When the period interval time was 100 ms, a peak phenomenon appeared in the rod, and the formation accuracy of the rod was low. When the period interval time was 50 ms, the droplet at the top of the rod spread well, and the formation precision of the rod was high. The number of droplets and number of cycles affected the droplet deposition heat input and droplet volume. Finally, large size CPLS containing 20 rows and 90 columns with a single-layer-double-layer pyramid mixture was prepared. The overall size deviation was not greater than 0.8 mm and its relative error was < 7.2%.