prBAS EN ISO 21068-1:2025

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).