Atomization Characteristics of Droplet and Morphologies of Arc Sprayed Ni-Al Particles and Composition Coatings

Abstract

Droplet atomization characteristics and its morphology in twin-wire arc sprayed (TWAS) Ni-Al were explored in depth. Both numerical model and theoretical method were built for calculating the process of the droplet deformation and breakup in air flow, which based on the standard k-ε model and the volume of fluid (VOF) dual-phase flow model. The atomization characteristics of double droplets and three droplets were also studied in the atomization process by simulation. The micro structure and the morphology of the composite coatings were analyzed by SEM and TEM. The experimental results indicate that TWAS droplets are the process of explosive breakup or two steps breakup. Morphology of the TWAS prepared Ni-20wt.%Al and Ni-5wt.%Al particles was accordingly characterized by SEM. The phase compositions of the Ni-Al particles were obtained by EDS. By testing the velocity of sprayed particles, the change rule of particles with spray pressure was obtained. Ni twins are discovered in the Ni-Al coating due to rapid cooling in TWAS process.

Twin Wire Arc Sprayed Coatings for Power Industry Applications – process parameters optimization study

“…Both temperature and velocity are related to the level of splats flattering, related consequently to the hardness. The obtained dependencies agree with the results of previous studies [4,7,8,9].…”

“…There are many papers focusing on studying the deposition parameter-microstructure-properties relationships for high kinetic processes such as HVOF, HVOF, or for plasma-based spray processes, such as APS. In the case of TWAS technology, the number of studies, focusing on the optimization of deposition process parameters, are rather limited [4][5][6][7][8][9]. On the basis of these works, it can be assumed that although the connection between the microstructure and properties of the coatings and the technological parameters of TWAS deposition is not as direct as it is with other, more controllable spraying technologies, there are clear connections valid for different types of materials.…”