Increasing the energy efficiency of plasma spraying by means of simulation-based process development

• Applicant: Professorin Dr.-Ing. Kirsten Bobzin
• Subject Area: Production Automation and Assembly Technology
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 442323795

Plasma spraying is one of the most versatile process variants in the Thermal Spraying coating technology. However, according to the current state of the art, only a small portion of the available energy is utilized to accelerate and melt the particles. In the previous project, a solution approach was developed to increase the energy efficiency. A fixed nozzle extension was used to surround the plasma jet, thereby preventing mixing with the ambient air. The effect of this nozzle extension on the plasma jet was first investigated through a numerical simulation model and subsequently experimentally. The results show that this separation increases the plasma temperature and reduces the air mass fraction in the plasma jet, thereby improving the energy efficiency. Throughout the current project, the developed numerical model will be used in combination with numerical algorithms, such as particle swarm optimization, to optimize the geometry of the nozzle extension for given process parameters. The effect on the coating properties will be determined by final coating experiments. In the previous project, the functionality of the fixed nozzle extension for increasing the plasma temperature and thus the energy efficiency of plasma spraying was proven through simulation-supported process development. In the present project, a complementary approach to increase the energy efficiency, i. e. the preheating of the injected feedstock particles, will be investigated. By utilizing the radiant energy of the plasma jet, the carrier gas and the particles injected into the plasma can be preheated without external energy. The preheating mechanism designed around the plasma jet can also help minimize the mixing of the plasma jet with ambient air. This preheating method will be developed using numerical simulations followed by experimental testing, and its potential to further enhance the energy efficiency will be assessed. By efficiently utilizing the otherwise wasted heat energy of the plasma jet, this project can make a further contribution to increase the energy efficiency of plasma spraying.

• DFG Programme: Research Grants