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, C_total;

—     free carbon, C_free;

—     silicon carbide, SiC;

—     free silicon (Si_free);

—     free aluminium (Al_free);

—     free magnesium (Mg_free);

—     free iron (Fe_free);

—     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).