High temperature dielectric constant of KI

1969 ◽  
Vol 47 (9) ◽  
pp. 969-973 ◽  
Author(s):  
Suresh Chandra
Keyword(s):  
Dielectric Constant ◽  
Thermal Expansion ◽  
High Temperature ◽  
Melting Point ◽  
Thermal Expansion Coefficient ◽  
Standing Wave ◽  
Expansion Coefficient ◽  
Room Temperature ◽  
Polarization Effects ◽  
Complex Polarization

The dielectric constant of KI crystal has been measured at 23.6 GHz from room temperature to near the melting point. A K-band microwave standing wave ratio technique was used for this purpose to avoid complex polarization effects. It was found that the dielectric constant of KI increases more rapidly than for KCl and KBr, presumably due to its larger thermal expansion coefficient at high temperatures.

High Temperature Dielectric Constants of Rubidium Halides

1972 ◽  
Vol 50 (10) ◽  
pp. 1053-1054 ◽  
Author(s):  
Suresh Chandra ◽  
Jai Prakash
Keyword(s):  
Dielectric Constant ◽  
High Temperature ◽  
Melting Point ◽  
Standing Wave ◽  
Room Temperature ◽  
Dielectric Constants ◽  
Wave Technique

The high temperature dielectric constants of RbCl, RbBr, and RbI are measured at 24.6 GHz from room temperature to near melting point. A standing wave technique has been used. The dielectric constant of RbBr is observed to increase at a faster rate than that of RbCl and RbI.

Determining the High-temperature Properties of Thin Films Using Bilayered Cantilevers

1998 ◽  
Vol 546 ◽  
Author(s):  
H. Tada ◽  
P. Nieva ◽  
P. Zavracky ◽  
I.N. Miaoulis ◽  
P.Y. Wong
Keyword(s):  
Thin Films ◽  
Thermal Expansion ◽  
High Temperature ◽  
Thermal Expansion Coefficient ◽  
High Temperatures ◽  
Expansion Coefficient ◽  
Room Temperature ◽  
Temperature Property ◽  
Beam Curvature ◽  
High Temperature Property

AbstractHigh-temperature applications of microelectromechanical systems (MEMS), especially in new temperature sensor designs, require an accurate knowledge of the temperature-dependent thermophysical properties of the materials. Although the measurement of the mechanical properties of materials at room temperature has been widely conducted, the same techniques often cannot be used for high-temperature property measurements. In this study, a new technique was developed to find the thermal expansion coefficient of thin films at high temperatures. Bilayered cantilever beams undergo thermally induced deflection at high temperatures, which can be measured and correlated to material properties. An imaging system was developed for the experimental measurement of the beam curvature for temperatures up to 1000°C. To find the high-temperature property of thin films, a bilayered beam, consisting of polycrystalline silicon and silicon dioxide, was designed such that the change in the property of SiO2 had little effect on the curvature of the beam. Furthermore, numerical analysis showed that the Young's modulus of Si also had negligible effect on the curvature. Therefore, the analytical model for beam curvature was simplified to be only a function of the thermal expansion coefficient of Si layer. Using this model, the thermal expansion coefficient of polycrystalline Si film was determined for temperature range between room temperature and 1000°C. The method can be easily modified to find the Young's modulus of Si, as well as properties of SiO2.

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.

Interface Microstructure and Thermal Expansion Mismatch in Alloy N/316H Bimetallic Plates

2019 ◽  
Author(s):  
Jia Xiao ◽  
Zhijun Li ◽  
Li Jiang ◽  
Linfeng Ye ◽  
Kun Yu ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Explosive Welding ◽  
Thickness Ratio ◽  
Interface Microstructure ◽  
Thermal Expansion Mismatch ◽  
Bond Interface ◽  
Bimetallic Plate

Abstract Two Alloy N/316H bimetallic plates have been fabricated by explosive welding and rolling technologies respectively. Metallographic observations indicate that the rolled bimetallic plate has a straight bond interface, in which some cavities and precipitates exist. While the explosive welded plate shows a wavy bond interfaces. The interface thermal expansion mismatch between the two alloys were evaluated in the two plates at high temperature. Results show that the thermal expansion coefficient of 316H is larger than that of Alloy N. The thermal expansion coefficient of the substrate plates depends on the thickness ratio between Alloy N and 316H, which reaches the maximum when the ratio is 1:4.

High Temperature Stability of Zirconium Tungstate

2020 ◽  
Vol 993 ◽  
pp. 771-775
Author(s):  
Ping Zhai ◽  
Xiao Feng Duan ◽  
Da Qian Chen
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Solid Phase ◽  
Coefficient Of Thermal Expansion ◽  
Negative Thermal Expansion ◽  
Tungstic Acid ◽  
High Temperature Stability ◽  
Zirconium Tungstate

In this paper, zirconium tungstate ceramic with negative thermal expansion coefficients was prepared from zirconium oxide and tungstic acid by solid phase synthesis and high temperature quenching technique with a sintering temperature of 1200 °C. The phase structure of the material was determined by X ray and the thermal expansion coefficient was measured by dilatometer, while the TG-DTA analysis of the prepared material was also carried out. The results showed that zirconium tungstate with high purity could be obtained by rapid chilled while fired at 1200 °C. The coefficient of thermal expansion at 300 °C was minus 8.5413 × 10-6K-1, which is identical with the theoretical value. The thermal expansion coefficient of the material was negative fired lower than 750 °C, while it was positive fired higher than 750 °C, and this indicates that the decomposition temperature of zirconium tungstate is about 750 °C.

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