Brown Aluminum Oxide

Crystal Form

Alpha alumina trigonal system

Chemical nature

Amphoteric

Reaction with acids

Subject to mild attack by aqua and/or hydrofluoric acid

Reaction with Alkalies

Very slight with strong hot solution only

Oxidation-reduction effects

None

True Density(g/cm³)

3.97

Hardness

Knoop(kg/cm²)

2000-2200

Moh’s

9.0

Color

Dark Brown

Color after firing

Light blue

Melting point

2000°C

Max Usable temperature

1900°C

Specific heat (cal/g.°C)

0.26(20-29°C)

Coefficient of thermal conductivity
(cal/cm².sec.°C)

Room temperature

900°C

0.047

0.013

Electrical resistivity (Wcm)

30°C

300°C

900°C

1600°C

10¹⁶

10¹³

10⁵

10⁴

Coefficient of liner expansion     (x10^-6)

7-9(0-1600°C)

Grit Item

10 – 90

100 – 180

220 - 220

230-400

500-1200

Al2O3

94.5 - 97.0

93.5 min

92.5 min

91.0 min

89.0 min

TiO2

1.5 - 3.8

1.5 - 3.8

1.5 - 3.8

4.0 max

4.0 max

Grit No.

Magnetic Matters Content

16#-30

<0.0380

36#-60#

<0.0280

70-120#

<0.0230

150#-220#

<0.0170

Grit No.

Micron

Grit No.

Micron

Grit No.

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

China GB 2477-83

JIS

FEPA(84) / DIN(70)

ISO(77)

Grit No.

Norminal size range(µm)

Grit No.

ds50 value (µm)

Grit No.

ds50 value (µm)

Grit No.

ds50 value (µm)

Standard werte der Mikro-F-Reihe

Sedigraph 5000D

240

60.0±4.0

P240

58.5±2.0

280

52.0±3.0

P280

52.2±2.0

W63

63 - 50

320

46.0±2.5

F230/53

53±3.0

50.0±3.0

P320

46.2±1.5

W50

50 - 40

360

40.0±2.0

F240/45

44.5±2.0

42.0±2.0

P360

40.5±1.5

400

34.0±2.0

P400

35.0±1.5

W40

40 - 28

500

28.0±2.0

F280/37

36.5±1.5

34.5±1.5

P500

30.2±1.5

600

24.0±1.5

F320/29

29.2±1.5

27.7±1.5

P600

25.8±1.0

W28

38 - 20

700

21.0±1.3

F360/23

22.8±1.5

21.6±1.5

P800

21.8±1.0

800

18.0±1.0

F400/17

17.3±1.0

16.5±1.0

P1000

18.3±1.0

W20

20 - 14

1000

15.5±1.0

F500/13

12.8±1.0

12.3±1.0

P1200

15.3±1.0

W14

14 - 10

1200

13.0±1.0

1500

10.5±1.0

F600/9

9.3±1.0

9.0±1.0

W10

10 - 7

2000

8.5±0.7

W7

7 - 5

2500

7.0±0.7

F800/7

6.5±1.0

6.3±1.0

W5

5 - 3.5

3000

5.7±0.5

F1000/5

4.5±0.8

4.5±0.8

F1200/3

3.1±0.5

3.1±0.5

for general purposes

for general purposes

for bonded abrasives

for coated abrasives

Group Sizes of BFA

Mixed Sizes of BFA

Sizes
(mm)

Chemical Content

Sizes
(mm)

Chemical Content

8-5
5-3
3-1
1-0

Al₂O₃>94.50
SiO₂<1.2
Fe₂O₃<0.2
TiO₂<3.8
CaO<0.5
MgO<0.4

25-0
10-0
5-0
3-0

Al₂O₃>94.50
SiO₂<1.2
Fe₂O₃<0.2
TiO₂<3.8

Vitrified tools

Lapping

Resinoid tools

Blasting

Polishing

Scrubing

Tumbling

Deburring

Self-tumbling

Non-slip

Lapping compound

Wire saw