UNE-EN ISO 21068-1:2024

This part of ISO 21068 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 magnesiachrome materials;i) refractories containing carbon and/or silicon carbide except those described in a) to g) above.The items of chemical analysis described in ISO 21068, Parts 1 to 3 are as follows:1) loss on drying (LOD);2) loss on ignition (LOI);3) total carbon, Ctotal;4) free carbon, Cfree;5) silicon carbide, SiC;6) free silicon (Sifree);7) free aluminium (Alfree);8) free magnesium (Mgfree);9) free iron (Fefree);10) silicon(IV) dioxide (SiO2);11) aluminium oxide (Al2O3);12) iron(III) oxide (Fe2O3);13) titanium(IV) oxide (TiO2);14) calcium oxide (CaO);15) magnesium oxide (MgO);16) sodium oxide (Na2O);17) potassium oxide (K2O);18) chromium(III) oxide (Cr2O3);19) zirconium oxide (ZrO2);20) boron oxide (total boron calculated as B2O3);21) nitrogen;22) oxygen;23) nitrides (undifferentiated: Si3N4, AlN, BN, sialon, oxy-nitrides, etc.).ISO 21068-4 describes XRD methods for the determination of mineralogical phases typically apparent in nitride and oxy-nitride bonded silicon carbide refractory products.