Particle Melting Behavior during High-Velocity Oxygen Fuel Thermal Spraying

Correlation between particle size and porosity of Fe-based amorphous coating

“…Particle velocity and temperature are the most significant factors in determining the porosity of an HVOF coating [10,15]. Increased particle velocity generally correlates with improved splat deformation but has a weak effect on porosity.…”

“…In addition, many numerical and experimental studies have reported that both particle velocity and temperature are strongly dependent on the key process parameter of particle size [12-15]. For example, during HVOF Inconel 625 thermal spraying, the temperature of the particles significantly decreased with increasing particle size [10]. Furthermore, these simulation results also demonstrated that the velocity and temperature of the particles are strongly affected by particle size.…”

“…The porosity of HVOF sprayed coatings is strongly influenced by the structure of the deposit, which largely depends on the physical and chemical state of the particles during the point of impact with the substrate, including the particles' velocity, temperature, and degree of melting [10,11]. Hanson and Settles [11] found that, when the temperature of the particle temperature is kept near the melting point, highly dense coatings can be formed using relatively low-velocity particles.…”

“…Several previous numerical computational fluid dynamics (CFD) simulations have investigated the effect of particle size on the porosity of thermally sprayed Ni [16] and WC-Co [17] coatings. Continuum-type and stochastic models, which assume that the particles are fully melted at the point of impact with the substrate, have been developed to simulate microstructure formation of the coatings [18,19] to characterise the coating porosity in the HVOF thermal spray process [10]. However, these calculations do not consider the impact that the degree of particle melting has on the evolution of the particle temperature and the formation of the coating microstructure.…”

Shape evolution of a melting nonspherical particle

“…This problem is associated with melting of clusters of particles [21], melting or condensation in porous media [22,23], in suspensions [24] or in granular media [25][26][27], and melting of snow flakes [28,29] or other dendritic structures [30]. Melting of solid particles is a key element * roisman@sla.tu-darmstadt.de in thermal spraying technology [31,32] or in the production of spherical particles. This problem is also associated with phase-change materials for energy storage components [33].…”