We are proud to offer Lustrous Carbon (Coal Dust) Powder which is tailor made to act as an additive for imparting better finish to castings.
Lustrous Carbon (Coal Dust) is a carbon-containing additive which is added to the bentonite -bonded molding sands in order to reduce oxidation, minimize sand adhesion to the casting at shakeout, enhance casting surfaces and combat the occurrence of casting defects. At the same time the optimizing molding sand properties and performance.
Lustrous carbon (Coal Dust) formers are essentially organic in nature. They contain H – C compounds that volatilize under the effect of the
casting temperature. The gaseous atmosphere produced is supersaturated with carbon and exerts a reducing effect, preventing oxidation
defects such as Burnt-on sand, Graphite degeneration and other Chemical reactions. C super saturation ultimately becomes so extensive that pyro lytic carbon in the form of lustrous carbon (Coal Dust) precipitates directly onto the mold surface at elevated temperatures. The degree of super saturation in the mold atmosphere depends on the composition [Z] of the lustrous carbon former (C-H-O ratio), the carbon concentration [K] and the temperature [T] (LC =f[Z,K,T]).
The precipitation of lustrous carbon (coal dust) onto the hot mold wall reduces chemical reactions and the degree to which the mold face can be wetted by the molten metal. The gases produced influence the impact of the liquid metal against the mold material providing a so-called "cushioning effect" protecting the casting. The presence of lustrous carbon (coal dust) ensures good casting "peel" with excellent molding sand/casting separation at shakeout with optimum collapsibility and disintegration of the mold minimizing sand losses.
At high temperatures the lustrous carbon (coal dust) former itself becomes plastic and swells minimizing compressive stresses produced inside the mold due to the thermal expansion of silica. Swelling and the formation of carbon residues, help to stabilize moisture. Classic casting defects such as erosion, penetration and surface roughness can thus be prevented by the presence of such carbon carriers.
Good reasons for using our LC formers:
- Reduction in the wettability of the mold surface through the formation of a reducing gaseous hydrocarbon atmosphere
- Absorption of compressive stresses produced within the mold during casting
- Reduced environmental burden with organic crack emissions minimized due to a low consumption of additives
Maximum recyclability through improved mold collapse and sand/casting separation at shakeout. We have the right Lustrous Carbon (Coal Dust) formers for every application conditions. Our Lustrous Carbon (Coal Dust) Powder also acts as a partion joint between sand and metal in order to avoid distortion of metal surface after cooling. Because of Low Ash and High Volatiles
content, our Lustrous Carbon (Coal Dust) Powder evaporates from sand bath faster and does not allow effect of sand on the metal.
||50 - 60%
||50 - 55%
||40 - 50%