Ceramic Properties - Boron Nitride
BN is made using a hot pressing process, and comes as a lubricious white solid. It can be machined using standard carbide drills. Due to crystal stucture, BN is anisotropic electrically and mechanically. BN exhibits a high electrical resistance, low dielectric constant and loss tangent, low thermal expansion, chemical inertness, and good thermal shock resistance in ceramic parts.
There are several different purity levels for this material. All offer very high thermal conductivity and stability in inert and reducing atmospheres up to 2800C, and in 850C in oxidizing environments.
Typical uses include vacuum components, low friction seals, various electronic parts, nuclear applications, and plasma arc insulators.
Properties Units Test Value Physical Chemical Formula BN Density, r g/cm3 ASTM C20 2.28 Color white Crystal Structure hexagonal Water Absorption % @R.T. ASTM C373 0.0 - 1.0 Hardness Moh's 2 Hardness knoop (kg/mm2) Knoop 100g 25 - 205 Mechanical Compressive Strength MPa @ R.T. ASTM C773 23.5 Tensile Strength MPa @ R.T. ACMA Test #4 2.41 (1000 C) Modulus of Elasticity
GPa ASTM C848 675 Flexural Strength (MOR) MPa @ R.T. ASTM F417 51.8 Poisson's Ratio, u ASTM C818 0.05 Fracture Toughness, KIc MPa x m1/2 Notched Beam Test 2.6 Thermal Max. Use Temperature
(* denotes inert atm.)
C No load cond. 985 Thermal Shock Resistance DT (C) Quenching >1500 Thermal Conductivity W/m-K @ R.T. ASTM C408 20 Coefficient of Linear Thermal Expansion, al mm/m-C (~25C through 1000C) ASTM C372 1.0 - 2.0 Specific Heat, cp cal/g-C @ R.T. ASTM C351 0.19 Electrical Dielectric Constant 1MHz @ R.T. ASTM D150 4.08 Dielectric Strength kV/mm ASTM D116 374 Electrical Resistivity Wcm @ R.T. ASTM D1829 1013
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