Hot-Pressed BN
Momentive Hot-pressed BN is compacted at temperatures up to 2000°C and pressures up to 14MPa. B2O3 is introduced to help form a dense, strong engineering material that is remarkably easy to machine.
Several grades of hot-pressed boron nitride are available which differ in the type and amount of binder present. Standard grades, such as Momentive Performance Materials’ grade HBN, have 2-5 per cent B2O3 which can hydrate when exposed to moisture or high humidity.
This can result in limited thermal shock resistance. Other grades have a calcium addition which combines with the B2O3 to form a higher melting point glass binder which is less hygroscopic and gives improved performance at high temperatures (up to 1200°C). There is a high purity grade HBC from which the B2O3 binder has been removed. The process yields a diffusion bonded ceramic that actually increases in strength with increasing temperature. This grade HBC is commonly used at temperatures over 2000°C.
In addition to sharing the performance characteristics of powdered hexagonal boron nitride from which it is made— chemically inert, high thermal shock resistance, high electrical resistance, high thermal conductivity, excellent corrosion resistance, low loss tangent and low dielectric constant—HPBN adds some strengths of its own. It is not wetted by most molten metals including aluminum, antimony, bismuth, cadmium, copper, germanium, indium, iron, silicon, steel and tin. It does not react with halide salts and many other chemicals. Because HPBN is relatively soft, it is easily machined. This is unusual among ceramics used in electronics applications and reduces the need for precision surfaces to maximize contact area.
Applications for HPBN
The unique combination of thermal and electrical characteristics found in hot-pressed boron nitride, coupled with its machinability, have caught the attention of design engineers in a variety of industries. A sampling of today’s uses includes:
Momentive Hot-pressed BN is compacted at temperatures up to 2000°C and pressures up to 14MPa. B2O3 is introduced to help form a dense, strong engineering material that is remarkably easy to machine.
Several grades of hot-pressed boron nitride are available which differ in the type and amount of binder present. Standard grades, such as Momentive Performance Materials’ grade HBN, have 2-5 per cent B2O3 which can hydrate when exposed to moisture or high humidity.
This can result in limited thermal shock resistance. Other grades have a calcium addition which combines with the B2O3 to form a higher melting point glass binder which is less hygroscopic and gives improved performance at high temperatures (up to 1200°C). There is a high purity grade HBC from which the B2O3 binder has been removed. The process yields a diffusion bonded ceramic that actually increases in strength with increasing temperature. This grade HBC is commonly used at temperatures over 2000°C.
In addition to sharing the performance characteristics of powdered hexagonal boron nitride from which it is made— chemically inert, high thermal shock resistance, high electrical resistance, high thermal conductivity, excellent corrosion resistance, low loss tangent and low dielectric constant—HPBN adds some strengths of its own. It is not wetted by most molten metals including aluminum, antimony, bismuth, cadmium, copper, germanium, indium, iron, silicon, steel and tin. It does not react with halide salts and many other chemicals. Because HPBN is relatively soft, it is easily machined. This is unusual among ceramics used in electronics applications and reduces the need for precision surfaces to maximize contact area.
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| Momentive Hot Pressed Boron Nitride Shapes |
Applications for HPBN
The unique combination of thermal and electrical characteristics found in hot-pressed boron nitride, coupled with its machinability, have caught the attention of design engineers in a variety of industries. A sampling of today’s uses includes:
• As a boron source in p-type diffusion furnaces
• As a heat sink in transistor packages
• As a substrate
• As an interface and nozzle material for manufacture of amorphous alloys
• As a break ring in horizontal continuous casting of steel
• As a mold for casting carbon steel, low alloy steels and stainless steel
• As insulators and source holders for ion implant systems
• As insulators for vacuum furnaces
• As glass-forming tools and refractories
• As windows in aerospace re-entry vehicles
• As microwave windows for high frequency satellite applications
• As an ablative material for aerospace applications
• As plasma rings
• As electrical insulating spacers for tungsten resistance heaters
• As refractory wall liners and crucibles in a variety of hot metal applications
For more details you can get in touch with us at : innovative_growth@yahoo.co.in or 9910899409
• As a heat sink in transistor packages
• As a substrate
• As an interface and nozzle material for manufacture of amorphous alloys
• As a break ring in horizontal continuous casting of steel
• As a mold for casting carbon steel, low alloy steels and stainless steel
• As insulators and source holders for ion implant systems
• As insulators for vacuum furnaces
• As glass-forming tools and refractories
• As windows in aerospace re-entry vehicles
• As microwave windows for high frequency satellite applications
• As an ablative material for aerospace applications
• As plasma rings
• As electrical insulating spacers for tungsten resistance heaters
• As refractory wall liners and crucibles in a variety of hot metal applications
For more details you can get in touch with us at : innovative_growth@yahoo.co.in or 9910899409
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