Initially, the chemical analysis of each buildup was obtained by using an X-ray spectrometer.
Cathodoluminescence uses a stream of electrons that are shot at the refractory buildup surface at a specific angle.
These results will be used to verify the findings in the cathodoluminescence study and observe any possible nucleation sites where the buildup might begin growing.
In this case the ceramic buildup was a composite of magnesia and alumina in the form of spinel.
In one case, for example, it was determined that buildup occurred as a result of residual MgO carried over from melting treated ductile returns, combining with silica [SiO.
This study also demonstrated the following: * As the concentration of metallic oxides and sulfides within the molten metal increases, there is an increased propensity to form a ceramic buildup or clog in the inductor channels or throat openings.
Residual oxides from remelting solid charges can be a source of buildup.
Many different buildup compositions are generated from this source.
The size of the scrap or charge material will also contribute to the throat buildup.
To reduce this source of buildup, the use of calcium-bearing compounds such as fluorspar, calcium carbide or limestone will also contribute to the buildup as these cause an erosion of either the refractory in the molten metal transfer equipment or the channel furnace uppercase refractory.
The presence of sulfides, whether inherent to the molten metal or as a by-product of any treatment step, will influence the buildup.