BS EN ISO 21068-1:2008

This standard BS EN ISO 21068-1:2008 Chemical analysis of silicon-carbide-containing raw materials and refractory products is classified in these ICS categories:

• 81.080 Refractories

This part of ISO 21068 gives definitions and specifies techniques for the preparation of samples for the chemical analysis of silicon-carbide-containing raw materials and refractory products including:

1. graphite brick containing silicon carbide;

2. silicon carbide brick (includes the bricks containing silicon nitride);

3. refractories containing carbon and/or silicon carbide mixed with clay;

4. refractories containing carbon and/or silicon carbide mixed with silica (and fused silica);

5. refractories containing carbon and/or silicon carbide mixed with high alumina material;

6. refractories containing carbon and/or silicon carbide mixed with magnesia (and dolomite);

7. refractories containing carbon and/or silicon carbide mixed with chrome mineral or magnesia-chrome materials;

8. 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 3 are as follows:

1. loss on drying (LOD);

2. loss on ignition (LOI);

3. total carbon, C_total;

4. free carbon, C_free;

5. silicon carbide, SiC;

6. free silicon (Si_free);

7. free aluminium (Al_free);

8. free magnesium (Mg_free);

9. free iron (Fe_free);

10. silicon(IV) oxide (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.).

The range of determination specified in this part of ISO 21068 is given in Table 1.

Table 1

Range of determination

Component	Range % by mass
LOI	–10 to 99
Ctotal	0,01 to 99
Cfree	0,01 to 99
SiC	3 to 99
Sifree	0,1 to 10
Alfree	0,1 to 10
Mgfree	0,1 to 10
Fefree	0,1 to 10
SiO2	0,1 to 95
Al2O3	0,1 to 95
Fe2O3	0,1 to 15
TiO2	0,1 to 5
CaO	0,1 to 60
MgO	0,1 to 95
Na2O	0,1 to 5
K2O	0,1 to 5
Cr2O3	0,1 to 40
ZrO2	0,1 to 1
B2O3	0,1 to 5
Si3N4	0,1 to 35