Chemical& Physical Properties

CrystalForm

Alpha aluminatrigonal system

Chemicalnature

Amphoteric

Reaction withacids

Attck less thanbrown fused alumina

Reaction withAlkalies

Very slightwith strong hot solution only

Oxidation-reductioneffects

None

True Density(g/cm3)

3.96

Hardness

Knoop(kg/cm2)

2000-2200

Moh''s

9.0

Color

White

Color afterfiring

White

Meltingpoint

2000oC

Max usabletemperature

1900oC

Specific heat(cal/g.oC )

20oC

100oC

0.183

0.217

Coefficient ofthermal conductivity(cal/cm2.secoC)

Roomtemperature

900oC

0.047

0.013

Electricalresistivity (Wcm)

30oC

300oC

900oC

1600oC

1016

1013

105

104

Coefficient ofliner expansion (x10-6)

25oC-500oC

25oC-1000oC

25oC-1500oC

7.58

8.52

9.29

ChemicalComposition

Grit

12# -90#

100# -220#

230# -400#

500# -1200#

Al2O3

98.5min

98.5min

98.0min

97.0min

Na2O

0.5max

0.7max

0.8max

0.8max

MagneticMaterial Content (%by weight) 

Grit

MagneticMaterial Content

16#-24#

<0.0023

30#-120#

<0.0021

150#-240#

<0.0015

Available grainsizes

GritNo.

Micron

GritNo.

Micron

GritNo.

Micron

10

2360 ~2000

30

710 ~600

80

212 ~180

12

2000 ~1700

36

600 ~500

90

180 ~150

14

1700 ~1400

40

500 ~425

100

150 ~125

16

1400 ~1180

46

425 ~355

120

125 ~106

20

1180 ~1000

54

355 ~300

150

106 ~75

22

1000 ~850

60

300 ~250

180

90 ~63

24

850 ~710

70

250 ~212

220

75 ~53