新型大气长层流等离子体喷涂方法和研究进展

A novel atmospheric plasma spray method was proposed, using a newly development direct current non-transferred arc plasma torch which generated a long, stable and silent plasma jet in atmospheric environment without any other auxiliary equipment. The lengths of these plasma jets varied from 100 to 1000 mm in atmospheric environment. The fluid characteristics of plasma jets presented a laminar or quasi-laminar with a low-level noise less than 80 dB at the same time. Moreover, the lengths of the plasma jets increased with the increase of the output power at every constant gas flow rate and decreased with the increase of total gas flow rate at every constant output power, providing a super-long particle flight time in the atmospheric plasma spray process. The research history and current researches of these laminar plasma technologies are listed. The microstructure evolution, particle heating and motion were all presented by using six different types of powders. The effects of particle flowing characteristics to the formation of coatings were discussed. The results show a super long distance of particle heating and motion in the experiment when the system operates in a low output power and gas flow rate. Thus, low particle velocity and surface temperature are obtained. The variations of microstructures of the coatings and particle melting during the deposition can through different operation conditions, such as lengths of the plasma jet or spraying distances. Mass of vapor deposited coatings are obtained by using metallic or ceramic powders.