Nov 15 2011
Table of Contents
Introduction
Chemical Composition, Properties and Applications
Physical Properties of Hot-Pressed Boron Nitride
About Ceramic Substrates and Components
Introduction
Boron Nitride is a synthetic, technical ceramic material, which is available in powder, solid, aerosol and liquid forms. In solid form, it can be machined easily with commonly used metalworking tools. Boron Nitride has outstanding thermal characteristics including high thermal conductivity and excellent thermal shock resistance. Boron Nitride in solid form is available in three grades, each having different characteristics
The most common grade, HPBN is manufactured by hot pressing. Its crystal structure is hexagonal. The anisotropy of the HPBN platelet structure is created using the uniaxial densification technique. As a result of the anisotropy, different physical properties are observed parallel or perpendicular to the pressing direction. HPBN is non toxic and can be easily machined.
Chemical Composition, Properties and Applications
The chemical composition, properties and applications of Boron Nitride are tabulated bellow:
|
Applications
|
Properties
|
Chemical Composition
|
|
Electrical insulators for high temperature applications |
Excellent thermal shock behaviour
|
Boron
Nitrogen
Oxygen
|
40-42.6%
49-52.9%
3-5%
|
|
Thermocouple tubes |
High electrical resistivity
|
Calcium
SiO2
|
2-3%
0.2%
|
|
Crucibles and nozzels for molten metals |
Chemically stable
|
B203
Others
|
0.4
0.03%
|
|
Rolls and support elements in the glass manufacturing industries |
Extraordinary thermo cycling properties
|
|
|
|
|
High temperature material
|
|
|
Standard shapes and maximum dimensions:
-
HPBN is hot-pressed in block shapes up to 280mm diameter and 300mm height.
Physical Properties of Hot-Pressed Boron Nitride
|
Pressing Direction
|
|
|
Parallel
|
Perpendicular
|
|
Compressive Strength |
|
MPa
|
30
|
48
|
|
Young's modulus |
RT |
GPa
|
34.1
|
75.2
|
|
Flexural Strength |
RT |
MPa
|
43.7
|
60.2
|
|
|
1000°C |
|
12.5
|
17.4
|
|
|
1500°C |
|
11.8
|
17.0
|
|
Density |
|
g/cm³
|
1.9-1.95
|
1.9-1.95
|
|
Vickers Hardness |
|
kg/mm²
|
12.01
|
10.88
|
|
Thermal Expansion |
RT-350°C |
x10-6K-1
|
0.0
|
0.0
|
|
|
RT-700°C |
|
0.67
|
0.0
|
|
|
RT-1500°C |
|
2.95
|
0.87
|
|
Thermal Conductivity |
RT |
W/mK
|
27.22
|
30.98
|
|
|
300°C |
|
23.03
|
27.22
|
|
|
500°C |
|
21.77
|
26.38
|
|
|
1000°C |
|
20.52
|
25.54
|
Max usage temperature
Inert atmosphere |
|
°C
|
1500
|
1500
|
|
Oxide atmosphere |
|
|
850
|
850
|
|
Volume resistivity |
|
Ω.cm
|
|
|
|
|
RT |
|
1.7x1014
|
4.0x1014
|
|
|
150°C |
|
1.7x1014
|
1.9x1014
|
|
Dielectric Strength |
|
KV/mm
|
>39.4
|
>39.4
|