Abstract
Non-metallic inclusions less than 50μm are presently impossible to be removed during typical liquid metal processing operations, even though their presence can have a negative impact on the properties of final products. The major purposes of injecting gas and generating microbubbles within a liquid metal bath include superior intermixing of reactants, enhancement of mass transfer or chemical reaction rates, as well as facilitating the removal of deleterious inclusions. Previous studies have shown that ~500 μm bubbles are required to float out sub-50 μm diameter particles/inclusions in tundish-type scenarios. Our current work demonstrates that microbubbles having a size range of around 500 μm can be generated in a novel experimental apparatus using high-speed rotational shear at very low gas flow rates. Additionally, a new LiMCA (Liquid Metal Cleanliness Analyzer) setup was used to measure the sizes of microbubbles generated in low melting point alloys, for different rotational speeds and injected gas flow rates. The successful detection and measurement of bubbles using the new setup proved that the theory behind LiMCA can be used for microbubble/inclusion monitoring in various liquid melts.