Ceramic Coatings and Glass Additives for Improved S i C ‐Based Filters for Molten Iron Filtration

Reticulated silicon carbide ( S i C ) ceramic filters are prepared with modified coatings in an attempt to improve mechanical properties of the sintered filter. Two classes of coatings are used: mixtures of non‐ S i C ceramic and sintering aid and mixtures of S i C and glass. Various candidate ceramics, sintering aids, and glasses are screened. The most promising coatings are determined to be silica with 5 wt% bismuth oxide and S i C with ≤10 wt% Spruce Pine Batch glass. Filters with these coatings are prepared and subjected to mechanical abuse. Both coatings improve the ruggedness of the filter relative to the standard uncoated S i C type. Filters with <10 wt% glass additive were subjected to molten metal impingement and filtration of liquid gray iron at 1510°C. Those with 5 wt% glass or more softened during filtration. Those with 2.5 wt% glass or less survived without failure.