S 2315 (OTTO) Sodium metasilicate pentahydrate, ≥95% Cas 10213-79-3 - used As a silicate electrolyte in plasma electrolytic oxidation (PEO) coating. S 2315 (OTTO) Sodium metasilicate pentahydrate, ≥95% Cas 10213-79-3 - used For the synthesis of sintered mullite ceramics (3Al2O3·2SiO2) by the co-precipitation method.