Solid Boron Nitride Grade AX05 is one of the highest purity hexagonal boron nitride solids available and a wise choice for applications where corrosion resistance is more important than wear resistance. It is a diffusion bonded ceramic and does not depend on B₂O₃ to other binders for mechanical integrity and, consequently, it is non-wet by almost all molten metals. This ultra purity advantage allows for applications and uses not provided by other hot pressed boron nitride solids, such as crucibles for high-purity molten metals.

Commonly used in applications that demand very high thermal conductivity such as nozzles with small orifices.





Density ρ

1.85 g/cm³ at 20 °C

Porosity Vvoid

12.57 %

open porosity


Flexural strength σbend

17.9 MPa at 25 °C

based on 4-pt bend test sample size = 51mm x 4mm x 3mm

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Flexural strength, transverse σbendT

21.4 MPa at 25 °C

based on 4-pt bend test sample size = 51mm x 4mm x 3mm

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Coefficient of thermal expansion α

1E-6 1/K at 1500 °C

Coefficient of thermal expansion, transverse αtrans

3E-7 1/K at 1500 °C

Max service temperature Tmax

850 °C

in air

Max service temperature, inert Tmax,inert

2000 °C

Specific heat capacity cp

350 J/(kg·K) at 20 °C

Thermal conductivity λ

78 W/(m·K) at 20 °C

Thermal conductivity, transverse λtrans

130 W/(m·K) at 20 °C


Dielectric constant εr

4 [-] at 20 °C

Electrical resistivity ρel

1.00E+12 Ω·m at 20 °C

Electrical resistivity, transverse ρel,trans

1.00E+14 Ω·m at 20 °C

Loss tangent tanδ

1.2E-3 [-] at 20 °C

at 8.8GHz

Loss tangent, transverse tanδtrans

1.2E-3 [-] at 20 °C

at 8.8 GHz

Chemical properties


Weight %



1 %



0.05 %



0.04 %



0.02 %


Technological properties

Application areas

High temperature electrical insulators and vacuum furnace supports which require electrical resistivity, high temperature strength, thermal shock resistance and low chemical reactivity. Crucibles and containers for high purity molten metals. Insulators and source fixtures for ion implantation systems which require high temperature purity and electrical insulation. Setter plates for the processing of other advanced materials which require stable, inert surfaces. Nozzles for powdered metal spraying.

General machinability

Grade AX05 can be machined to extremely close tolerances using standard high speed “tool steel” equipment. Machining by grinding may be used if preferred or stringent tolerances are required. Threads can be machined using taps and dies. Cutting oils and coolants should not be used for any reason.


The key features are: Chemical Properties - Grade AX05 is extremely inert and non-wet by many molten materials such as metals, glasses, halide salts and other reagents. The chemical stability allows Grade AX05 to provide a stable, non-reactive material for nozzles, feed- throughs, crucibles and supports. Thermal Properties - Grade AX05 has minimal thermal expansion, high thermal conductivity and use temperature in certain inert atmospheres over 2000°C. Thermal shock stability is excellent over a wide range of use temperatures. Mechanical Properties - Grade AX05 yields increasing relative strength vs. temperature. This important feature provides higher temperature performance to applications previously unattainable with B₂O₃ to other bonded boron nitrides. Electrical Properties - Grade AX05 is transparent to microwave energy. It also provides high resistivity and dielectric strength with a low loss tangent and dielectric constant. These characteristics make AX05 an excellent material for high power, low loss insulators, containers and fixtures.

This material data has been provided by Goodfellow.

All metrics apply to room temperature unless otherwise stated. SI units used unless otherwise stated.
Equivalent standards are similar to one or more standards provided by the supplier. Some equivalent standards may be stricter whereas others may be outside the bounds of the original standard.