Spraying Using Magneto-Plasma-Dynamic Arc Jet Generator

摘要

In magneto-plasma-dynamic (MPD) arc jet generators, plasmais accelerated by electromagnetic body forces. Silicon nitridereactive spraying was carried out using an MPD arc jetgenerator with crystal silicon rods and nitrogen gas. Becausehigher-velocity, higher-temperature and higher-density andlarger-area plasmas are produced with the MPD arc jetgenerator than those with conventional thermal plasmatorches, nitriding of silicon can be enhanced. A dense anduniform β-Si3N4 coating 30 μm thick was formed after 200shots at a repetitive frequency of 0.03 Hz with a dischargecurrent of 9 kA and a substrate temperature of 700 °C. TheVickers hardness reached about 1300. Furthermore, siliconcarbide and aluminum nitride sprayings were conducted withthe same spraying system. Surface modification is understudy with lots of chemically reactive gases. All resultsshowed that the MPD arc jet generator had high potential forspraying and surface modification.