The present study has been made to obtain fundamental knowledge on the mechanism of contact of particles with liquid metal during powder injection. A spherical body was dropped onto a stagnant mercury bath and the behavior of the penetration of the sphere was recorded by a high speed cinecamera. The spheres tested were of glass, sapphire, stainless steel, and hastelloy B (diameter =0.159 0.953 cm).
The sphere impinging the liquid surface makes a cavity. Then the sphere jumps up from the surface of the cavity when the entry velocity is lower than a critical one. At higher entry velocities, however, the impinging sphere dips into the liquid while the cavity disappears; shortly afterward the sphere rises back to the surface with a mercury film. Based on the measurement of the jumping height of the sphere and the time during which the sphere is immersed in the liquid, the critical entry velocity for the particle penetration into the liquid has been determined.
Taking into account the inertia of the liquid surrounding the sphere and the cavity formation, one has given a new model describing the penetrating behavior of the sphere into the liquid. The experimental results are well explained by the theoretical calculation. It is shown that the cavity formation plays an important role in the mechanism of contact of particles with liquid metal.