ČSN EN ISO 21068-1

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).