Aluminum Nitride fibers from a Thermoplastic Organoaluminum Precursor

1987 ◽  
Vol 108 ◽  
Author(s):  
John D. Bolt ◽  
Fred N. Tebbe
Keyword(s):  
Thermal Conductivity ◽  
Dielectric Constant ◽  
Thermal Expansion ◽  
High Temperature ◽  
Aluminum Nitride ◽  
Melt Spinning ◽  
Elevated Temperatures ◽  
Fine Particles ◽  
Bulk Ceramic ◽  
Higher Temperature

ABSTRACTA new organoaluminum polymer (EtAINH)n(Et2AlNH2)m·AlEt3 derived from triethylaluminum and ammonia, is thermoplastic at elevated temperatures and a glassy solid at ambient temperature. As a thermoplastic it can be processed in certain shapes, solidified, cured and transformed to dense aluminum nitride with retention of its shape. Aluminum nitride fibers are prepared by melt spinning the polymer, pyrolyzing in ammonia and at high temperature in nitrogen. The AlN microstructure forms as very fine particles at 400–600°C, coarsens at higher temperature, and densifies at 1600–1800 °C into polycrystalline AlN with submicron grains. Mechanical strength, thermal expansion and dielectric constant are consistent with bulk ceramic values. Initial thermal conductivity deduced from composite measurements is 82 W/m°K in fibers containing 0.5 to 1.0 percent oxygen.

Mullite Ceramics for the Application to Advanced Packaging Technology

1989 ◽  
Vol 154 ◽  
Author(s):  
Jun Tanaka ◽  
Satoshi Kajita ◽  
Masami Terasawa
Keyword(s):  
Thermal Conductivity ◽  
Dielectric Constant ◽  
Thermal Expansion ◽  
Aluminum Nitride ◽  
Heat Sink ◽  
High Thermal Conductivity ◽  
System A ◽  
Lower Dielectric Constant ◽  
Advanced Packaging ◽  
Mullite Ceramics

AbstractMullite ceramics were developed for multilayered packages, which have a lower dielectric constant and a nearer thermal expansion to that of silicon than those of alumina. The multilayered mullite packages are manufactured by using a similar cofired technology with tungsten or molybdenum to the conventionally used alumina system. A new brazing material and a new lead material were developed to be combined with the mullite ceramics Multilayered mullite packages with a brazed aluminum nitride heat sink, which has a high thermal conductivity, were developed to compensate a low thermal conductivity of the mullite itself. The packages are one of the highest performance packages.

WIELAND-K88

Alloy Digest ◽  
2005 ◽  
Vol 54 (12) ◽  
Keyword(s):  
Thermal Conductivity ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Stress Relaxation ◽  
Copper Alloy ◽  
Elevated Temperatures ◽  
Heat Treating ◽  
Relaxation Resistance ◽  
Temperature Performance ◽  
Very High

Abstract Wieland K-88 is a copper alloy with very high electrical and thermal conductivity, good strength, and excellent stress relaxation resistance at elevated temperatures. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: CU-738. Producer or source: Wieland Metals Inc.

Sintering Behavior of Plasma-Sprayed Sm2Zr2O7 Coating

2010 ◽  
Author(s):  
Jianhua Yu ◽  
Huayu Zhao ◽  
Shunyan Tao ◽  
Xiaming Zhou ◽  
Chuanxian Ding
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
High Temperature ◽  
Thermal Expansion Coefficient ◽  
Thermal Barrier Coating ◽  
Expansion Coefficient ◽  
Sintering Behavior ◽  
Thermal Barrier ◽  
Barrier Coating ◽  
Plasma Sprayed

Plasma-sprayed thermal barrier coating (TBC) systems are widely used in gas turbine blades to increase turbine entry temperature (TET) and better efficiency. Yttria stabilized zirconia (YSZ) has been the conventional thermal barrier coating material because of its low thermal conductivity, relative high thermal expansion coefficient and good corrosion resistance. However the YSZ coatings can hardly fulfill the harsh requirements in future for higher reliability and the lower thermal conductivity at higher temperatures. Among the interesting TBC candidates, materials with pyrochlore structure show promising thermo-physical properties for use at temperatures exceeding 1200 °C. Sm2Zr2O7 bulk material does not only have high temperature stability, sintering resistance but also lower thermal conductivity and higher thermal expansion coefficient. The sintering characteristics of ceramic thermal barrier coatings under high temperature conditions are complex phenomena. In this paper, samarium zirconate (Sm2Zr2O7, SZ) powder and coatings were prepared by solid state reaction and atmosphere plasma spraying process, respectively. The microstructure development of coatings derived from sintering after heat-treated at 1200–1500 °C for 50 h have been investigated. The microstructure was examined by scanning electron microscopy (SEM) and the grain growth was analyzed in this paper as well.

scholarly journals Sandwich-structured polymer nanocomposites with high energy density and great charge–discharge efficiency at elevated temperatures

2016 ◽  
Vol 113 (36) ◽  
pp. 9995-10000 ◽  
Author(s):  
Qi Li ◽  
Feihua Liu ◽  
Tiannan Yang ◽  
Matthew R. Gadinski ◽  
Guangzu Zhang ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
High Temperature ◽  
Energy Density ◽  
Polymer Nanocomposites ◽  
Elevated Temperatures ◽  
High Energy ◽  
Operating Conditions ◽  
High Dielectric ◽  
Discharge Efficiency ◽  
Charge Discharge

The demand for a new generation of high-temperature dielectric materials toward capacitive energy storage has been driven by the rise of high-power applications such as electric vehicles, aircraft, and pulsed power systems where the power electronics are exposed to elevated temperatures. Polymer dielectrics are characterized by being lightweight, and their scalability, mechanical flexibility, high dielectric strength, and great reliability, but they are limited to relatively low operating temperatures. The existing polymer nanocomposite-based dielectrics with a limited energy density at high temperatures also present a major barrier to achieving significant reductions in size and weight of energy devices. Here we report the sandwich structures as an efficient route to high-temperature dielectric polymer nanocomposites that simultaneously possess high dielectric constant and low dielectric loss. In contrast to the conventional single-layer configuration, the rationally designed sandwich-structured polymer nanocomposites are capable of integrating the complementary properties of spatially organized multicomponents in a synergistic fashion to raise dielectric constant, and subsequently greatly improve discharged energy densities while retaining low loss and high charge–discharge efficiency at elevated temperatures. At 150 °C and 200 MV m−1, an operating condition toward electric vehicle applications, the sandwich-structured polymer nanocomposites outperform the state-of-the-art polymer-based dielectrics in terms of energy density, power density, charge–discharge efficiency, and cyclability. The excellent dielectric and capacitive properties of the polymer nanocomposites may pave a way for widespread applications in modern electronics and power modules where harsh operating conditions are present.

scholarly journals High-entropy (Nd0.2Sm0.2Eu0.2Y0.2Yb0.2)4Al2O9 with good high temperature stability, low thermal conductivity and anisotropic thermal expansivity

2020 ◽  
Author(s):  
Zifan Zhao ◽  
Huimin Xiang ◽  
Heng Chen ◽  
Fu-zhi Dai ◽  
Xiaohui Wang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Rare Earth ◽  
High Temperature ◽  
Phase Stability ◽  
Temperature Phase ◽  
Low Thermal Conductivity ◽  
High Entropy ◽  
Anisotropic Thermal Expansion

Abstract The critical requirements for the environmental barrier coating (EBC) materials of silicon-based ceramic matrix composites (CMCs) including good tolerance to harsh environments, thermal expansion match with the interlayer mullite, good high-temperature phase stability and low thermal conductivity. Cuspidine-structured rare-earth aluminates RE4Al2O9 have been considered as candidates of EBCs for their superior mechanical and thermal properties, but the phase transition at high temperatures is a notable drawback of these materials. To suppress the phase transition and improve the phase stability, a novel cuspidine-structured rare-earth aluminate solid solution (Nd0.2Sm0.2Eu0.2Y0.2Yb0.2)4Al2O9 was designed and successfully synthesized inspired by entropy stabilization effect of high entropy ceramics. The as-synthesized (Nd0.2Sm0.2Eu0.2Y0.2Yb0.2)4Al2O9 exhibits close thermal expansion coefficient (6.96×10-6 /K at 300-1473 K) to that of mullite, good phase stability from 300 K to 1473 K, and low thermal conductivity (1.50 W·m-1·K-1 at room temperature). In addition, strong anisotropic thermal expansion has been observed compared to Y4Al2O9 and Yb4Al2O9. The mechanism for low thermal conductivity is attributed to the lattice distortion and mass difference of the constituent atoms while the anisotropic thermal expansion is due to the anisotropic chemical bonding enhanced by the large size rare earth cations.

Thermal conductivity and thermal expansion of Ir3X (X = Ti, Zr, Hf, V, Nb, Ta) compounds for high-temperature applications

2003 ◽  
Vol 80 (2) ◽  
pp. 385-390 ◽  
Author(s):  
Yoshihiro Terada ◽  
Kenji Ohkubo ◽  
Seiji Miura ◽  
Juan M Sanchez ◽  
Tetsuo Mohri
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
High Temperature ◽  
Temperature Applications

High-Temperature Properties of Nuclear Graphite

2008 ◽  
Author(s):  
Tracy L. Albers ◽  
Lionel Batty ◽  
David M. Kaschak
Keyword(s):  
Thermal Conductivity ◽  
Tensile Strength ◽  
Thermal Expansion ◽  
High Temperature ◽  
Physical Properties ◽  
Nuclear Reactors ◽  
Specific Resistance ◽  
Coefficient Of Thermal Expansion ◽  
Unique Combination ◽  
Nuclear Graphite

The unique combination of physical properties inherent to graphite makes it an attractive material for use as a moderator in high-temperature nuclear reactors (HTR’s). High-temperature physical properties of three nuclear grade graphites manufactured by GrafTech International Holdings Inc. (GrafTech) (PCEA, PCIB-SFG, and PPEA) have been determined experimentally and are presented here. Tensile strength, Young’s modulus, thermal conductivity, specific resistance, and coefficient of thermal expansion (CTE) data are collected at temperatures from 25 °C to as high as 2000 °C and are found to be consistent with classical graphite behavior.

scholarly journals High Temperature Microelectromechanical Systems Using Piezoelectric Aluminum Nitride

2014 ◽  
Vol 2014 (HITEC) ◽  
pp. 000040-000046
Author(s):  
Benjamin A. Griffin ◽  
Scott D. Habermehl ◽  
Peggy J. Clews
Keyword(s):  
Thin Films ◽  
High Temperature ◽  
Aluminum Nitride ◽  
Mechanical Strength ◽  
Gas Turbines ◽  
Power Plants ◽  
Microelectromechanical Systems ◽  
Elevated Temperatures ◽  
Coefficient Of Thermal Expansion ◽  
Temperature Limit

We report on the efforts at Sandia National Laboratories to develop high temperature capable microelectromechanical systems (MEMS). MEMS transducers are pervasive in today's culture, with examples found in cell phones, automobiles, gaming consoles, and televisions. There is currently a need for MEMS transducers that can operate in more harsh environments, such as automobile engines, gas turbines, nuclear and coal power plants, and petroleum and geothermal well drilling. Our development focuses on the coupling of silicon carbide (SiC) and aluminum nitride (AlN) thin films on SiC wafers to form a MEMS material set capable of temperatures beyond 1000°C. SiC is recognized as a promising material for high temperature capable MEMS transducers and electronics because it has the highest mechanical strength of semiconductors with the exception of diamond and its upper temperature limit exceeds 2500°C, where it sublimates rather than melts. Most transduction schemes in SiC are focused on measuring changes in capacitance or resistance, which require biasing or modulation schemes that can withstand elevated temperatures. Instead, we are coupling temperature hardened, micro-scale SiC mechanical components with piezoelectric AlN thin films. AlN is a non-ferroelectric piezoelectric material, enabling piezoelectric transduction at temperatures exceeding 1000°C. AlN is a favorable MEMS material due to its high thermal, electrical, and mechanical strength. It is also closely matched to SiC for coefficient of thermal expansion.

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