Nitride Carbide

Aluminium Nitride and Silicon Nitride

Aluminium nitride is an interesting material and is one of the best materials to use if high thermal conductivity is required. When combined with its excellent electrical insulation properties, aluminium nitride is an ideal heat sink material for many electrical and electronic applications.

Silicon nitride is an extremely hard material and is very useful for applications in which physical wear is of great importance. Silicon nitride also has very good thermal shock characteristics.

Typical applications: electronic components; heat sinks; turbine blades

Silicon Carbide

Like oxides and nitrides, silicon carbide is a very hard wearing material, again requiring diamond-grinding methods to process once fired. Although not exclusively, carbides are used mainly for applications in which physical wear is a major consideration. They are amongst the hardest materials available.

Typical applications: valve seats; bearings.

Nitrides and Carbides Physical Properties

name	ALN	Silicon Nitride	Porcelain	Silicon Nitride hot pressed	Silicon Carbide	Steel(mild)
colour	fawn/grey	grey	white	grey	black	grey
density	3.3g/cm	2.5g/cm	2.4g/cm³	3.3g/cm	3.1g/cm	7.85kg dm
porosity	0%		0%	0%	0%	0%
poissons ratio		0.2		0.28	0.24	0.27-0.30
thermal conductivity	180 Wm/°C	10-15 Wm/°C	2.06Wm/°C	15-20 Wm/K	150 Wm/K	50 Wm/°C
coeffcient of expansion	3.8 x 10^-6/deg;C		6.5x10^-6 20-800°C			11x10/°C
dielectric strength	20 KV/mm		25 KV/mm
dielectric constant	9 1MHZ	10
dielectric loss tangent	0.001 1MHZ
flexual strength	360 MPa	200 MPa		800 MPa	400 MPa
hardness	1100 Vickers	1100 Vickers	7-8 Mohs	1500 Vickers	3000 Vickers
volume resistancy	>10¹⁴ ohm/cm	>10¹⁰ ohm/cm		>10¹⁰ ohm/cm	>10¹⁰ ohm/cm
max. use temp	1800°C	1150°C		1150°C	1300°C
thermal expansivity		3.1 500- 1300		3.3 500- 1300K	3x 10^sup-6°C	11x10/°C
specific heat	800 J/KgK	1100 J/KgK		800 J/KgK	1100 J/KgK	450J/kgK
compressive strength		550 MPa	480 MPa	2000 MPa	2000 MPa