Ceramic Spools

Item

Test Condition

Unit&Symbol

95%Alumina ceramics

99%Alumina ceramics

99.7%Alumina ceramics

The main chemical ingredient

Al2O3

Al2O3

Al2O3

Bulk Density

g/cm3

3.6

3.89

3.96

Maximum Use Temperature

1450°C

1600°C

1650°C

Water absorption

%

0

0

0

ROHS Hardness

≥85

≥89

≥89

Flexural strength

20° C

MPa (psi x 10³)

358 (52)

550

550

Compressive Strength

20° C

MPa (psi x 10³)

2068 (300)

2600(377)

2600(377)

Fracture Toughness

K(I c)

Mpa m^1/2

4-5

5.6

6

Coefficient of

thermal expansion

25-1000° C

1X 10^-6/°C

7.6

7.9

8.2

Coefficient of

thermal conductivity

20° C

W/m °K

16

30.0

30.4

Thermal Shock Resistance

Tc

°C

250

200

200

Dielectricity constant

1MHz.25°C

9

9.7

9.7

Dielectric strength

ac-kV/mm (ac V/mil)

8.3 (210)

8.7 (220)

8.7 (220)

Volume Resistivity

100°C

ohm-cm

> 10¹³

> 10¹⁴

> 10¹⁴

Electric appliance industry                                     

Automotive industry

1.Heat treatment furnace 

and toughened furnace

3.Good resistance 

to thermal impact

4.Small thermal expansion 

coefficient 

Mechanical industry              

Engineer industry 

2.Inner liner tube and heating 

tube in electric furnace

5.Good chill and abrupt 

heat properties

6.Resistance to acid and 

alkali corrosion