Processing, mechanical properties and oxidation behavior of TaC and HfC composites containing 15 vol% TaSi2 or MoSi2

2009 ◽  
Vol 24 (6) ◽  
pp. 2056-2065 ◽  
Author(s):  
Diletta Sciti ◽  
Laura Silvestroni ◽  
Stefano Guicciardi ◽  
Daniele Dalle Fabbriche ◽  
Alida Bellosi
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
High Temperature ◽  
Mechanical Strength ◽  
Hot Pressing ◽  
Room Temperature ◽  
Oxidation Behavior ◽  
Temperature Stability ◽  
High Temperature Stability ◽  
Better Than

Fully dense HfC and TaC-based composites containing 15 vol% TaSi2 or MoSi2 were produced by hot pressing at 1750–1900 °C. TaSi2 enhanced the sinterability of the composites and nearly fully dense materials were obtained at lower temperatures than in the case of MoSi2-containing ones. The TaC-based composites performed better than HfC composites at room temperature, showing values of mechanical strength up to 900 MPa and a fracture toughness of 4.7 MPa·m1/2. However, preliminary oxidation tests carried out in air at 1600 °C revealed that HfC-based composites have a superior high temperature stability compared to TaC-based materials.

Microstructure and Mechanical Properties of SiC Whisker-Reinforced ZrB2 Ultra-High Temperature Ceramic

2008 ◽  
Vol 368-372 ◽  
pp. 1730-1732 ◽  
Author(s):  
Ping Hu ◽  
Xing Hong Zhang ◽  
Jie Cai Han ◽  
Song He Meng ◽  
Bao Lin Wang
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
High Temperature ◽  
Flexural Strength ◽  
Hot Pressing ◽  
Room Temperature ◽  
Pressing Temperature ◽  
Sintering Time ◽  
Microstructure And Mechanical Properties ◽  
Ultra High Temperature

SiC whisker-reinforced ZrB2 matrix ultra-high temperature ceramic were prepared at 2000°C for 1 h under 30MPa by hot pressing and the effects of whisker on flexural strength and fracture toughness of the composites was examined. The flexural strength and fracture toughness are 510±25MPa and 4.05±0.20MPa⋅m1/2 at room temperature, respectively. Comparing with the SiC particles-reinforced ZrB2 ceramic, no significant increase in both strength and toughness was observed. The microstructure of the composite showed that the SiC whisker was destroyed because the SiC whisker degraded due to rapid atom diffusivity at high temperature. The results suggested that some related parameters such as the lower hot-pressing temperature, a short sintering time should be controlled in order to obtain SiC whiskerreinforced ZrB2 composite with high properties.

TD-NICKEL

Alloy Digest ◽  
1965 ◽  
Vol 14 (7) ◽  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Melting Point ◽  
Physical Properties ◽  
Temperature Stability ◽  
Heat Treating ◽  
High Temperature Stability ◽  
Temperature Performance

Abstract TD-NICKEL is a dispersion hardened nickel alloy offering high-temperature stability and useful mechanical properties virtually to the melting point of the base metal. It is easy to fabricate. It is capable of operating for long periods of time at high temperatures without degradation of mechanical properties. This datasheet provides information on composition, physical properties, and tensile properties as well as fracture toughness and fatigue. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Ni-103. Producer or source: E. I. DuPont de Nemours & Company Inc..

scholarly journals Bulk high-entropy nitrides and carbonitrides

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Olivia F. Dippo ◽  
Neda Mesgarzadeh ◽  
Tyler J. Harrington ◽  
Grant D. Schrader ◽  
Kenneth S. Vecchio
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Configurational Entropy ◽  
Temperature Stability ◽  
High Hardness ◽  
Valence Electron Concentration ◽  
High Temperature Stability ◽  
High Entropy ◽  
Rule Of Mixtures ◽  
Traditional Ceramics

AbstractHigh-entropy ceramics have potential to improve the mechanical properties and high-temperature stability over traditional ceramics, and high entropy nitrides and carbonitrides (HENs and HECNs) are particularly attractive for high temperature and high hardness applications. The synthesis of 5 bulk HENs and 4 bulk HECNs forming single-phase materials is reported herein among 11 samples prepared. The hardness of HENs and HECNs increased by an average of 22% and 39%, respectively, over the rule-of-mixtures average of their monocarbide and mononitride precursors. Similarly, elastic modulus values increased by an average of 17% in nitrides and 31% in carbonitrides over their rule-of-mixtures values. The enhancement in mechanical properties is tied to an increase in the configurational entropy and a decrease in the valence electron concentration, providing parameters for tuning mechanical properties of high-entropy ceramics.

scholarly journals Dynamic Water Effect on the High Temperature Stability of Asphalt Mixture

2012 ◽  
Vol 5 ◽  
pp. 352-357 ◽  
Author(s):  
Ming Hao Hou ◽  
Yi Qiu Tan ◽  
Bin Hu
Keyword(s):  
High Temperature ◽  
Asphalt Mixture ◽  
Temperature Stability ◽  
High Viscosity ◽  
Test Method ◽  
Water Effect ◽  
High Temperature Stability ◽  
Air Voids ◽  
Working Together ◽  
Better Than

This paper introduces dynamic water effect into the test, develops a laboratory test device for simulating the dynamic water effect on asphalt pavement, and puts forward a test method of dynamic water effect working together with load, water and temperature. Based on this method, the high temperature stability of seven kinds of asphalt mixtures with the factors of asphalt grade, gradation and air voids are studied. The research shows that the effect of dynamic water can take adverse effect for the high temperature stability of asphalt mixture. The effect degree is different under different factors. It is the most disadvantaged when the air voids of the mixture is near 10%, the skeleton structure gradation of mixture is better than the suspended structure at the most disadvantage air voids, and the mixture made of high viscosity asphalt is more affected when the temperature is higher.

Deformation of an extruded nickel beryllide between room temperature and 820 °C

1991 ◽  
Vol 6 (12) ◽  
pp. 2653-2659 ◽  
Author(s):  
G.M. Pharr ◽  
S.V. Courington ◽  
J. Wadsworth ◽  
T.G. Nieh
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Elevated Temperature ◽  
Flow Stress ◽  
Strain Hardening ◽  
Room Temperature ◽  
High Temperature Strength ◽  
Compression Tests ◽  
Tension And Compression ◽  
Better Than

The mechanical properties of nickel beryllide, NiBe, have been investigated in the temperature range 20–820 °C. The room temperature properties were studied using tension, bending, and compression tests, while the elevated temperature properties were characterized in compression only. NiBe exhibits some ductility at room temperature; the strains to failure in tension and compression are 1.3% and 13%, respectively. Fracture is controlled primarily by the cohesive strength of grain boundaries. At high temperatures, NiBe is readily deformable—strains in excess of 30% can be achieved at temperatures as low as 400 °C. Strain hardening rates are high, and the flow stress decreases monotonically with temperature. The high temperature strength of NiBe is as good or better than that of NiAl, but not quite as good as CoAl.

Influence of Double-Doped Admixtures on Asphalt Mixture Performance

2012 ◽  
Vol 557-559 ◽  
pp. 329-333
Author(s):  
Zhong Run Zheng ◽  
Chao Zhao ◽  
Yi Feng Zhao ◽  
Pei Song
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Asphalt Mixture ◽  
Temperature Stability ◽  
High Temperature Stability ◽  
Rutting Resistance ◽  
Splitting Test ◽  
Improvement Effect ◽  
Low Temperature Cracking ◽  
Better Than

This paper introduces an asphalt mixture that mixed with different admixtures, rutting resistance agent and lignin fiber, at the same time. Rutting test and freeze-thaw splitting test are used to analyze rutting resistance on the high temperature and low temperature cracking of the asphalt mixture. The experiments with different mixes material composition are conducted to analysis various properties of the two admixtures on the mixture, especially the high temperature stability, low temperature crack resistance and the law of improvement effect. In addition, the experiments also determine the optimal asphalt content of different type of mixtures. The results showed that the single-doped KTL rutting resistance or lignin fibers have some improvement in water temperature performance of asphalt mixture, stability improvement of double-doped admixture asphalt mixture is better than the single-doped asphalt mixture, such as KTL rutting resistance agents and lignin fibers

scholarly journals Room-temperature quantum cascade superluminescent light emitters with wide bandwidth and high temperature stability

2018 ◽  
Vol 26 (11) ◽  
pp. 13730 ◽  
Author(s):  
Chuncai Hou ◽  
Jialin Sun ◽  
Jiqiang Ning ◽  
Jinchuan Zhang ◽  
Ning Zhuo ◽  
...  
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Temperature Stability ◽  
High Temperature Stability ◽  
Light Emitters ◽  
Wide Bandwidth ◽  
Quantum Cascade

HIGH TEMPERATURE STABILITY OF OPTICAL PROPERTIES OF InAs QUANTUM DOTS REALIZED BY CONTROLLING OF QUANTUM DOTS ELECTRONIC SPECTRUM

2007 ◽  
Vol 06 (03n04) ◽  
pp. 283-286 ◽  
Author(s):  
N. V. KRYZHANOVSKAYA ◽  
A. G. GLADYSHEV ◽  
S. A. BLOKHIN ◽  
A. P. VASIL'EV ◽  
E. S. SEMENOVA ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
High Temperature ◽  
Room Temperature ◽  
Temperature Stability ◽  
High Energy ◽  
Energy Separation ◽  
High Temperature Stability ◽  
Carrier Distribution ◽  
Inas Quantum Dots

The optical properties of InAs /( Al ) GaAs quantum dots (QDs) overgrowth by thin AlAs / InAlAs layers are studied as a function of temperature from 10 to 500 K. The QDs emit at 1.27 μm at room temperature. It is shown that the QD energetic spectrum can be tuned by overgrowth of AlAs / InAlAs to provide high temperature stability of the QDs optical properties. Transport of carriers between neighboring QDs is absent, and the carrier distribution remains nonthermal up to room temperature. It is shown that suppression of the thermal escaping of the carriers from QDs is conditioned by high energy separation between ground and excited states, absence of wetting layer level, and increase of carrier localization energy in QDs in case of the Al 0.3 Ga 0.7 As matrix.

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