Topic
Thermal expansion
About: Thermal expansion is a research topic. Over the lifetime, 21040 publications have been published within this topic receiving 349407 citations. The topic is also known as: heat expansion.
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TL;DR: In this article, the authors measured the resistance and linear expansion of a disordered carbon-black polymer composite as a function of temperature from 25 to 180 degrees C. The results suggest the electrical conduction mechanism is the same below, during, and above the polymer melt temperature.
Abstract: I have measured the resistance and linear expansion of a disordered carbon‐black–polymer composite as a function of temperature from 25 to 180 °C. The sample resistance and thickness both increases monotonically as a function of temperature, with precipitous increases at the polymer melt temperature. The resistance versus thickness data show a monotonic increase with no precipitous changes at any point. These results suggest the electrical conduction mechanism is the same below, during, and above the polymer melt temperature. This casts doubt on some earlier models proposed to explain the resistance versus temperature behavior of these systems. These results also suggest a new approach to understanding the resistance versus temperature behavior by first developing a quantitative understanding of the resistance versus thickness behavior.
83 citations
TL;DR: In this article, a room-temperature wafer bonding method using surface activation by Ar-beam sputter etching was applied to the bonding between dissimilar materials, which is free from the various problems caused by the large thermal expansion mismatch between these materials during heat treatment.
Abstract: A room-temperature wafer bonding method using surface activation by Ar-beam sputter etching were applied to the bonding between dissimilar materials. LiNbO3, LiTaO3 and Gd3Ga5O12 wafers were successfully bonded to Si wafers without any heat treatment. This method is free from the various problems caused by the large thermal expansion mismatch between these materials during heat treatment in the conventional wafer bonding processes. The bond prepared by the Ar-beam treatment is so strong that fracture from inside the bulk materials is observed after the tensile test. The results of the bonding of Si wafers to both 128° Y-cut and Z-cut LiNbO3 wafers indicate that the influence of the crystal orientation on the bonding strength is negligible in this method. This method provides a very low damage bonding process for various material combinations regardless of any thermal expansion mismatch or crystal lattice mismatch.
83 citations
TL;DR: In this paper, a defect-perovskite structure of RETa3O9 bulk ceramics was characterized by X-ray diffraction (XRD) and Raman Spectroscope.
Abstract: Thermal barrier coatings (TBCs) are one of the most important materials in gas turbine to protect the high temperature components. RETa3O9 compounds have a defect-perovskite structure, indicating that they have low thermal conductivity, which is the critical property of TBCs. Herein, dense RETa3O9 bulk ceramics were fabricated via solid-state reaction. The crystal structure was characterized by X-ray diffraction (XRD) and Raman Spectroscope. Scanning electron microscope (SEM) was used to observe the microstructure. The thermal physics properties of RETa3O9 were studied systematically, including specific heat, thermal diffusivity, thermal conductivity, thermal expansion coefficients and high-temperature phase stability. The thermal conductivities of RETa3O9 are very low (1.33-2.37 W/m.K, 373-1073 K), which are much lower than YSZ and La2Zr2O7; and the thermal expansion coefficients range from 4.0×10-6 K−1 to 10.2×10-6 K−1 (1273 K), which is close to La2Zr2O7 and YSZ. According to the differential scanning calorimetry (DSC) curve there is not phase transition at the test temperature. Due to the high melting point and excellent high-temperature phase stability with these oxides, RETa3O9 ceramics were promising candidate materials for TBCs.
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83 citations
TL;DR: In this paper, the solid solution limit of Pb1−xSrxTiO3 was determined in the composition range of 0≤x≤1.0 at room temperature (RT).
83 citations
TL;DR: In this article, the spontaneous volume magnetostriction of Fe-Ni and Ni-Cu alloys at 0 K evaluated from their thermal expansion curves can be quantitatively explained on the basis of the collective electron model, using the density of states curve for nickel.
Abstract: Thermal expansion measurements were made on f.c.c. Fe-Ni and Ni-Cu alloys from liquid helium temperature up to 1000 K. The spontaneous volume magnetostriction of these alloys at 0 K evaluated from their thermal expansion curves can be quantitatively explained on the basis of the collective electron model, using the density of states curve for nickel. The lattice constants of these alloys at various temperatures evaluated from their thermal expansion curves deviate from Vegard's law in the Invar region. This deviation is discussed in connection with the magnetic state of the Invar alloy and with the origin of the Invar effects.
83 citations