Bottom blocks
Bottom blocks are used for lining the bottoms of aluminium electrolytic cells
|
Properties |
Units of measurement |
Typical values |
|||
|
Grade |
|
PB3 |
PB7 |
PB10 |
PBG2 |
|
Graphite content |
% |
30 |
70 |
100 |
graphitized |
|
Real density |
g/cm3 |
2.00 |
2.06 |
2.15 |
2.22 |
|
Bulk density |
g/cm3 |
1.58 |
1.64 |
1.61 |
1.70 |
|
Total porosity |
% |
21 |
21 |
|
|
|
Open porosity |
% |
16 |
17 |
20 |
18 |
|
Specific electrical resistance |
µОhm•m |
29 |
21 |
20 |
10 |
|
Heat conductivity |
W/m•K |
12 |
20 |
30 |
120 |
|
Compression strength |
MPa |
35 |
45 |
29 |
28 |
|
Flexural strength |
MPa |
11 |
15 |
10 |
12 |
|
Modulus of elasticity (Young's modulus) * |
GPa |
7 |
9 |
6 |
7 |
|
Rappoport's relative elongation in cryolite-alumina melt* |
% |
0.4 |
0.2 |
0.1 |
<0.2 |
|
Linear thermal expansion coefficient (20-520) °C |
10-6•K-1 |
2.2 |
3.0 |
3.4 |
2.6 |
|
Ash content |
% |
2.0 |
1.5 |
0.6 |
0.2 |
* - perpendicular to the direction of extrusion. The above values are average values and they do not constitute a specification.
Bottom blocks are manufactured on the basis of electrically calcined anthracite.
|
Dimensions of bottom blocks |
Maximum dimensions, mm |
Standard tolerances, mm |
|
Width |
720 |
± 3 |
|
Height |
490 |
± 3 |
|
Length |
3850 |
± 5 |
|
Groove |
rectangular trapezoidal cylindrical |
|