Silicon nitride coating targets ceramic components

Haldenwanger HalCoat comprises two grades of Si3N4 coating which can be applied to a variety of Morgan products including fused silica, silicon carbide and mullite bonded ceramics to offer a host of benefits from enhancing durability to avoiding contamination within a crucible.

Designed for fused silica rollers in applications such as hot stamping roller kilns, the standard purity of the first HalCoat grade helps prevent alloy build-up in the annealing process. The coating’s anti-wetting properties can extend the longevity of silica rollers, which are typically subject to layers of AlSi12 alloy layers forming on the surface.

The second HalCoat grade has been developed for the coating of fused silica crucibles, as Michael Rozumek, R&D Director for the Haldenwanger products business at Morgan Advanced Materials explains: “The latest advances in crucible technology utilise electro-magnetic fields to fine-tune the flow characteristics of melting silicon, which is invaluable in controlling the directional solidification of multi-crystalline photovoltaic silicon ingots. However, a knock-on effect is the considerable increase in mechanical wear within the crucible. Using HalCoat to treat these surfaces helps avoid delamination of the coating and therefore decreases the risk of contamination in the melt.”