ABSTRACT
Number of layers in contact 1 3 5 9 Effective capillary size, mm 0.6 0.15 0.04 0.01 As can be seen in Fig. 3.1 (curve 1) at least a 1000mm column of liquid metal is required to carry it through fine screen filters in ordinary filtration. Such a high value makes filtration impracticable. On the contrary, in a melt sonicated so as to obtain developed cavitation near the surface of a multilayer filter, the collapse of cavitation bubbles generates pulses of high pressure (Pmax » 100 MPa) near capillary channels. The melt can easily overcome the capillary pressure and the friction of liquid metal on the surface of filter channels. As a result, the melt readily passes through the filter’s capillary channels and the required height of liquid-metal column, i / us, (Fig. 3.1, curve 2) does not exceed 30-40 mm:
Figure 3.1 Effect of the mesh size of a multi-layer filter of glass cloth on the height H of the liquid metal column required for the metal to pass through the filter: (1) without sonication and (2) with sonication.
