Effect of chamber pressure on particle velocities in low pressure plasma spray deposition

Abstract

Listen

Translate article

A laser velocimeter has been used to measure spray particle velocities in a low pressure plasma spray system at chamber pressures ranging from 6.7 to 80 kPa (50 to 600 Torr). For Al 2O 3 spray powder with a mean diameter of 44 μm, peak particle velocities were of the order of 200 – 400 m s -1. The measured velocity distributions were strongly dependent upon spray chamber pressure, with the highest particle velocities at intermediate pressures of about 40 kPa (300 Torr). Particle velocities predicted with a simple analytical model are in reasonable agreement with experimental results close to the spray gun, where drag due to chamber gases can be neglected. This simple model also correctly predicts a particle velocity maximum at 45 kPa (340 Torr).