Item

N-1

N-2a

N-2b

N-3a

N-3b

N-4

N-5

N-6

Refractoriness

SK

31

30

30

29

29

28

27

23

°C

1750

1730

1730

1710

1710

1690

1670

1580

Chemical composition

Al₂O₃  ≥

40

39

34

34

32

32

31

31

Fe₂O₃  ≤

2.1

2.1

2.3

2.3

2.5

2.5

2.5

2.5

Apparent Porosity%  ≤

22

24

26

24

26

24

26

28

Bulk Density g/cm³    ≥

2.15

2.10

2.10

2.05

2.05

2.05

2.00

2.00

Cold Crushing Strength Mpa  ≥

30

25

20

20

15

20

15

15

0.2Mpa Refractoriness Under Load T_0.6 °C ≥

1400

1350

1350

1320

1320

1300

1300

1300

Reheating Linear Change(%)

1400°C 2h

+0.1- -0.4

+0.1- -0.5

+0.2- -0.5

1350°C 2h

+0.2- -0.5

+0.2- -0.5

+0.2- -0.5

+0.2- -0.5