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Changing thermal conductivity to improve the performance of Silicon Nitride components
January 17, 2006Enhancing the thermal conductivity of â-Si 3N 4 ceramics
Silicon nitride ceramics are important engineering materials due to their excellent properties such as fracture toughness, wear resistance and high temperature strength. They were originally developed to compete with metallic parts and now find application in such areas as engine components, glow plugs for diesel engines, cutting tools, bearings, nozzles and kiln furniture.
Thermal conductivity is an important physical property of Si 3N 4 ceramics. As the thermal conductivity strongly influences the rate of heat dissipation, this determines the reliability and performance of components in many industrial applications. In vehicle engines, low thermal conductivity is desired for heat insulation components to decrease fuel consumption, while high conductivity is required for cooling components with good thermal shock resistance.
Thermal conductivities of â-Si 3N 4 ceramics are known to range from 10 to 162 W.m -1.K -1 at room temperature. The thermal conductivity is greatly affected by processing variables such as purity of raw powders, type and amount of sintering aids, forming and sintering conditions.
In this paper published in AZojomo*, Koji Watari, Kiyoshi Hirao, Manuel E. Brito, Motohiro Toriyama and Kozo Ishizaki from National Institute of Advanced Industrial Science and Technology and Nagaoka University of Technology , have reviewed previous works and summarized results of the thermal conductivity of â-Si 3N 4 ceramics obtained under various conditions
The experimental observations and theoretical calculations showed that the amount and type of crystal defects in grains as well as thermal anisotropy are significant factors influencing the thermal conductivity of â-Si 3N 4 ceramics. Removal of crystal defects in grains is an important factor in increasing thermal conductivity of â-Si 3N 4 ceramics. This is achieved by using high purity powders, selection of effective sintering aids and controlling grain growth. Increasing thermal anisotropy in â-Si 3N 4 ceramics is also achieved by grain orientation during forming. By combining these processing techniques, it is possible to produces â-Si 3N 4 ceramics with higher thermal conductivities than 150 W.m -1.K -1 at room temperature.
AZoNetwork
Thermal conductivities of â-Si 3N 4 ceramics are known to range from 10 to 162 W.m -1.K -1 at room temperature. The thermal conductivity is greatly affected by processing variables such as purity of raw powders, type and amount of sintering aids, forming and sintering conditions.
In this paper published in AZojomo*, Koji Watari, Kiyoshi Hirao, Manuel E. Brito, Motohiro Toriyama and Kozo Ishizaki from National Institute of Advanced Industrial Science and Technology and Nagaoka University of Technology , have reviewed previous works and summarized results of the thermal conductivity of â-Si 3N 4 ceramics obtained under various conditions
The experimental observations and theoretical calculations showed that the amount and type of crystal defects in grains as well as thermal anisotropy are significant factors influencing the thermal conductivity of â-Si 3N 4 ceramics. Removal of crystal defects in grains is an important factor in increasing thermal conductivity of â-Si 3N 4 ceramics. This is achieved by using high purity powders, selection of effective sintering aids and controlling grain growth. Increasing thermal anisotropy in â-Si 3N 4 ceramics is also achieved by grain orientation during forming. By combining these processing techniques, it is possible to produces â-Si 3N 4 ceramics with higher thermal conductivities than 150 W.m -1.K -1 at room temperature.
AZoNetwork
Thermal Conductivity Current Events and Thermal Conductivity News RSSNC State Develops Material That Could Boost Data Storage, Save Energy
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Technique measures heat transport in the Earth's crust
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Seismic response to natural gas anomalies in crystalline rocks
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Promising new material that could improve gas mileage
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Baked slug: New method to test fireproofing material
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Looking for water on Mars
NASA's Phoenix Scout Lander reached Mars on May 25,, opened a soils lab, and started looking for water. Phoenix uses a robotic scoop arm to deliver regolith samples to the suite of instruments aboard the Lander--with one exception.
Cool! Nanoparticle research points to energy savings
Adding just the right dash of nanoparticles to standard mixes of lubricants and refrigerants could yield the equivalent of an energy-saving chill pill for factories, hospitals, ships, and others with large cooling systems, suggest the latest results from National Institute of Standards and Technology (NIST) research that is pursuing promising formulations.
Feeling the Heat: Berkeley Researchers Make Thermoelectric Breakthrough in Silicon Nanowires
Energy now lost as heat during the production of electricity could be harnessed through the use of silicon nanowires synthesized via a technique developed by researchers with the U.S. Department of Energy's (DOE) Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) at Berkeley.
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Imperial 73080 "Uni-tap" Non-corrosive Nylon Drive Rivet 1/4"x1" - Pkg/100 by Imperial "Uni-Tap" Drive Rivet Diameter: 1/4" Grip Range: 3/16 1/2 Rivet Length: 1" Uni-Tap® Nylon Drive Rivet. Withstands temperatures to -60° F. 100% nylon, F.D.A. approved. Tamper-resistant, vibration resistant. Low thermal conductivity. Non-corrosive. Available in three sizes. Quantity: 100 per package. Can be used in the following materials: plywood, plastic, studs, plexi-glass, concrete, sanitary wall systems, block, metal, brick, and foam insulation. |
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