Standards Development

Scope

ISO 21068 Part 1: Chemical analysis of raw materials and refractory products containing silicon carbide, silicon nitride, silicon oxynitride and sialon. -- Part 1: General information and sample preparation

Purpose

hemical 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 g) above. The items of chemical analysis described in ISO 21068, Parts 1 to 4 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 (total iron oxide calculated as 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.);

24) XRD-methods.

This Standard is relevant for the chemical analyses of silicon-carbide-containing raw materials and refractory products which are important for the industry. The ISO 21068 series contains analysis methods which are not entirely up to date and also references EN 12698-1 and vice versa. The scope of EN 12698-1 is also partly included in the scope of ISO 21068. The proposed revision ISO 21068 series aims to update the methods of ISO 21068 and to integrate the methods of EN 12698-1. Consequently the ISO 21068 can replace the EN 12698-1.