Ceramics

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Characteristics: A ceramic material is a solid, inorganic, non-metallic, often crystalline oxide, nitride or carbide material prepared by the action of heat and subsequent cooling. Some elements, such as carbon or silicon, may be considered ceramics. Ceramic materials are brittle, hard, strong in compression, weak in shearing and tension. They withstand chemical erosion that occurs in other materials subjected to acidic or caustic environments. Ceramics generally can withstand very high temperatures, such as temperatures that range from 1,000 °C to 1,600 °C (1,800 °F to 3,000 °F).

The earliest ceramics made by humans were pottery objects, including 27,000 year old figurines, made from clay, either by itself or mixed with other materials and hardened in fire. Later ceramics were glazed and fired to create a colored, smooth surface. Ceramics now include domestic, industrial and building products as well as a wide range of ceramic art. In the 20th century, new ceramic materials were developed for use in advanced ceramic engineering; for example, in semiconductors.

Technical ceramics can also be classified into three distinct material categories:

  • Oxides: alumina, beryllia, ceria, zirconia
  • Non-oxides: carbide, boride, nitride, silicide
  • Composite materials: particulate reinforced, fiber reinforced, combinations of oxides and non-oxides.

Each one of these classes can develop unique material properties because ceramics tend to be crystalline.

ALUMINA

GENERAL PROPERTIES

Specific Gravity:

3.90

Crystal Size:

Range 2-50 Micron, Avg 15-30

Surface Finish, As Fired:

26

Surface Finish, Ground:

17

Water Absorption:

None

Permeability:

Gas Tight

Flexural Strength, Typical 25 oC:

331 MPa (48 kpsi)

Flexural Strength, Typical 1000 oC:

193 MPa (28 kpsi)

Compressive Strength:

2071 MPa (>300 kpsi)

Modulus of Elasticity Typical 25 oC:

345 GPa (50 x 106 psi)

Color:

Ivory

Specific Heat @ 100 oC:

880 J/Kg-K, 0.21 Cal/g/oC

Maximum Temperature

 

(for no load conditions):

1750 oC, 3180 oF

Thermal Conductivity, 25 oC:

29.4 W/mK

Thermal Conductivity, 100 oC:

23.0 W/mK

Thermal Coefficient of Expansion:

 

25 - 200 oC:

6.7 x 10-6/oC

25 - 500 oC:

7.3 x 10-6/oC

25 - 800 oC:

7.8 x 10-6/oC

25 - 1000 oC:

8.0 x 10-6/oC

Dielectric Strength:

 

6.35 mm:

8.7 kv/mm

3.18 mm:

11.6 kv/mm

Spec. 1.27 mm:

16.5 kv/mm

AVAILABLE SIZES

Tubing

Rod

Outside  Diameter

Inside Diameter

Diameter

.250”

.156”

.020”

.250”

.188”

.029”

.375”

.250”

.040”

.500”

.250”

.048”

.500”

.375”

.060”

.625”

.500”

.080”

.750”

.563”

.125”

.750”

.500”

.250”

.875”

.625”

.375”

1.000”

.750”

.500”

1.125”

.875”

.625”

1.250”

.875”

.625”

1.375”

1.125”

1.00”

1.500”

1.250”

-

1.625”

1.375”

-

1.750”

1.500”

-

1.875”

1.625”

-

2.000”

1.750”

-

2.125”

1.875”

-

2.250”

2.000”

-

2.375”

2.125”

-

2.500”

2.250”

-

2.750”

2.375”

-

2.750”

2.500”

-

3.000”

2.750”

-

3.250”

2.875”

-

3.500”

3.125”

-

3.500”

3.250”

-

3.750”

3.375”

-

4.000”

3.625”

-

4.250”

3.875”

-

4.500”

4.125”

-

4.750”

4.375”

-

5.000”

4.625”

-

5.250”

4.875”

-

5.500”

5.125”

-

 

BORON NITRIDE

GENERAL PROPERTIES

Compressive Strength 25 oC (ACMA-1) lg/in2:

15 x 10.3

Modulus of Elasticity 25 oC (sonic):

11.4 x 10.6

Modulus of Rupture lb/in2

 

@ 25 oC:

6350

@ 1000 oC:

6760

@ 1350 oC:

3495

Density (ASTM C20), g/cm2:

1.90

Hardness:

205

Water absorption, % weight gain:

 

% weight gain in 168 hours @ 25oC

 

and 80%-100% relative humidity:

0.16

Thermal Expansion Degrees (C-1 x 10-6):

 

75oC - 5000oC:

0.0

75oC - 1000oC:

0.0

75oC - 1500oC:

0.09

75oC - 2000oC:

1.30

Thermal Conductivity, (W/moC):

 

@ 100oC:

39.7

@ 350oC:

31.2

@ 700oC:

28.8

Maximum Use Temperature in

 

Inert or reducing atmosphere (oC):

2000

Oxidizing Atmosphere (oC):

1200

AVAILABLE SIZES

Rods

.250”

.375”

.500”

.750”

.875”

1.00”

1.25”

1.50”

2.00”

Other sizes available upon request.