Al₂O₃

SiO₂

Fe₂O₃

CaO

Na₂O

K₂O

MgO

Other

25~80%

12~67%

<0.5%

<1.5%

<1.2%

<1.5%

<1.5%

<0.5%

Main crystal phase

AL₂O₃% 

item

Feldspar

Feldspar-mullite

Mullite

Mullite corundum

Corundum

20-30

30-45

45-70

70-90

≥90

Bulk densityg/cm

1.3-2.0

Water absorption  %

≤5

≤1

Acid resistance  %

≥98

Alkali resistance  %

≥80

≥82

≥85

≥90

≥95

Spalling resistance u8hg

≥250

≥300

≥500

≥700

≥800

refractoriness

≥1300

≥1400

≥1500

≥1600

≥1700

Crushing Strength N/piece

φ3

≥0.12

≥0.14

≥0.15

≥0.16

≥0.20

φ6

≥0.40

≥0.42

≥0.44

≥0.48

≥0.

φ8

≥0.48

≥0.52

≥0.60

≥0.62

≥0.65

φ10

≥0.60

≥0.7

≥0.80

≥0.90

≥1.00

φ13

≥1.00

≥1.10

≥1.30

≥1.50

≥2.00

φ16

≥1.50

≥1.60

≥1.80

≥2.30

≥2.60

φ20

≥1.80

≥2.00

≥2.30

≥2.80

≥3.20

φ25

≥2.50

≥2.80

≥3.20

≥3.60

≥4.00