1 Scope
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:
-
a) graphite brick containing silicon carbide;
-
b) silicon carbide brick (includes the bricks containing silicon nitride);
-
c) refractories containing carbon and/or silicon carbide mixed with clay;
-
d) refractories containing carbon and/or silicon carbide mixed with silica (and fused
silica);
-
e) refractories containing carbon and/or silicon carbide mixed with high alumina material;
-
f) refractories containing carbon and/or silicon carbide mixed with magnesia (and dolomite);
-
g) refractories containing carbon and/or silicon carbide mixed with chrome mineral or
magnesia-chrome materials;
-
h) 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, 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) 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 |