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 ISO 21068-2, ISO 21068-3 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).