Ceramic Properties - Aluminum Nitride
While AlN is not a 'new' material for ceramic parts, recent manufacturability developments over the past 15 years have made this an exciting and viable ceramic design material.
One of the most useful applications AlN has found is in replacing beryllium oxide (BeO) in the semiconductor industry. This substitution is due to BeO's toxicity. The thermal expansion coefficient of AlN is lower than BeO or alumina, and closely matches that of the silicon wafers used in electronics. Once a limitation for AlN's use in electronic applications there are now processes to metallize AlN.
There are electronic and structural grades of this material, classified as such by the thermal conductivity, which is controlled by the purity of the AlN. Pristine material is White, high purity is tan, and grey color indicates contaminants.
Properties Units Test Value Physical Chemical Formula AlN Density, r g/cm3 ASTM C20 3.25 Color white/tan/grey Crystal Structure hexagonal Water Absorption % @R.T. ASTM C373 0.0 Hardness Moh's 5 Hardness knoop (kg/mm2) Knoop 100g 1170 Mechanical Compressive Strength MPa @ R.T. ASTM C773 2068 Tensile Strength MPa @ R.T. ACMA Test #4 -- Modulus of Elasticity
GPa ASTM C848 308 Flexural Strength (MOR) MPa @ R.T. ASTM F417 428 Poisson's Ratio, u ASTM C818 0.25 Fracture Toughness, KIc MPa x m1/2 Notched Beam Test 3.5 Thermal Max. Use Temperature
(* denotes inert atm.)
C No load cond. 1600 Thermal Shock Resistance DT (C) Quenching 400 Thermal Conductivity W/m-K @ R.T. ASTM C408 82.3 - 170 Coefficient of Linear Thermal Expansion, al mm/m-C (~25C through 1000C) ASTM C372 4.6 - 5.7 Specific Heat, cp cal/g-C @ R.T. ASTM C351 0.25 Electrical Dielectric Constant 1MHz @ R.T. ASTM D150 8.0 - 9.1 Dielectric Strength kV/mm ASTM D116 15 Electrical Resistivity Wcm @ R.T. ASTM D1829 >1014
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