EN ISO 21068-1:2024

This document gives definitions and specifies techniques for the preparation of samples for the chemical analysis of silicon-carbide-containing raw materials and refractory products including:a) SiC raw materials;b) graphite brick containing silicon carbide;c) silicon carbide brick (includes the bricks containing silicon nitride, silicon oxynitride, sialon);d) refractories containing carbon and/or silicon carbide mixed with clay;e) refractories containing carbon and/or silicon carbide mixed with silica (and fused silica);f) refractories containing carbon and/or silicon carbide mixed with high alumina material;g) refractories containing carbon and/or silicon carbide mixed with magnesia (and dolomite);h) refractories containing carbon and/or silicon carbide mixed with chrome mineral or magnesia-chrome materials;i) refractories containing carbon and/or silicon carbide except those described in a) to h) above.The items of analysis described in ISO21068-2, ISO21068-3 and ISO 21068-4 are as follows:— loss on drying (LOD);— loss on ignition (LOI);— total carbon, Ctotal;— free carbon, Cfree;— silicon carbide, SiC;— free silicon (Sifree);— free aluminium (Alfree);— free magnesium (Mgfree);— free iron (Fefree);— silicon(IV) dioxide (SiO2);— aluminium(III) oxide (Al2O3);— iron(III) oxide (Fe2O3);— titanium(IV) oxide (TiO2);— calcium oxide (CaO);— magnesium oxide (MgO);— sodium oxide (Na2O);— potassium oxide (K2O);— chromium(III) oxide (Cr2O3);— zirconium(IV) oxide (ZrO2);— boron oxide (total boron calculated as B2O3);— nitrogen;— oxygen;— nitrides (undifferentiated: Si3N4, AlN, BN, sialon, oxy-nitrides, etc.);— mineralogical phases (XRD-methods).