The effect of traverse speed on deposition efficiency of cold sprayed Stellite 21

Abstract

Cold spraying of Stellite 21 powder on low carbon steel is performed to investigate the effect of traverse speed on the deposition efficiency (DE) of high-temperature alloys. Based on the simulation of particles' impact temperature and velocity, the initial experiments are performed at different gas pressures (32 and 40bar), temperatures (800 and 730°C), and stand-off distances (10, 25, and 40mm) at a constant traverse speed of 20mm.s-1. The experiments showed that high pressure, temperature, and short stand-off distance are preferred. The wipe test results indicated a potential of high DE at lower deposition flux over the substrate surface area at the first layer deposition. Thus, new tests are carried out at different traverse speeds ranging from 20 to 400mm.s-1 to adjust the deposition flux over the surface area of the substrate. The effect of traverse speed on DE and coating characteristics such as porosity and microhardness is studied as well. The results showed that the lower DE at lower traverse speed is related to the erosion of bonded particles due to the subsequent particles' impact. By increasing the traverse speed from 20 to 300mm.s-1, the DE increased more than twice. Induction time extension at higher traverse speed led to lower DE at 400mm.s-1