Application of a weak-ionized plasma high-temperature flow for material development and treatment of hazardous substance, and its flow diagnostics

点击翻译按钮获取中文摘要

Weak ionized high temperature nitrogen plasma flow could be generated stably with the electrical energy of 9 kW. Optical diagnostics for the flow field, where a blunt cylindrical body was set, was undertaken to measure vibrational and rotational temperatures of the nitrogen, T_<vib> and T_<rot>. T_<rot> was 3,000±500 K and 2,500±500 K for the case of Mach number 5 and 6, respectively. On the other hand, T_<vib> was almost constant in the whole flow field for the both cases. It is considered that the required time for a nitrogen molecule to collide with an electron and its collision frequency might be the major factors for the reason.Copper and zinc components of a disc-shaped brass, which was exposed in the plasma flow, was drastically changed spatially. Furthermore, this weak ionized nitrogen plasma flow was found to have the ability to make steel hard by the gas nitriding. The steel with the Vickers hardness of 230 changed to be harder with the Vickers value of 630, and hardness of the steel was also changed spatially. It also suggests that the ionized nitrogen flow can be utilized to product a functionally gradient material.Nitrogen and oxygen mixture was ionized by the arc-plasma flow facility and the neutral O I and N I atoms was investigated optically by the Boltzmann plots method. The excited O I and N I temperatures were delived to be 18,500 K and 17,500K, respectively. Therefore, the temperature of a free electron should be 18,000±500K.