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 synthesized binary oxide spinels composed of Mg, Al, Cr, Mn, Fe, Co, Ni, Cu, and Zn and measured their electrical conductivity in air at 500°-800°C.
Abstract: Binary oxide spinels composed of Mg, Al, Cr, Mn, Fe, Co, Ni, Cu, and Zn were synthesized. Electrical conductivity was measured in air at 500°–800°C. Thermal expansion was measured from room temperature to 1000°C. Ferrite spinels have thermal expansion coefficients of 11–12 ppm/K, compared with 7–9 ppm/K for other spinels except Cu–Mn and Co–Mn which show anomalous behavior. The highest electrical conductivity among transition metal spinels was found for MnCo2O4 (60 S/cm at 800°C) and Cu1.3Mn1.7O4 (225 S/cm at 750°C).
379 citations
TL;DR: In this article, the thermal and mechanical properties of a new negative photoresist, SU8, were characterized and the influence of curing conditions, such as baking temperature, baking time and UV dosage, on the thermal properties of the resultant coatings was studied in detail.
Abstract: The thermal and mechanical properties of a new negative photoresist, SU8, were characterized. The influence of curing conditions, such as baking temperature, baking time and UV dosage, on the thermal and mechanical properties of the resultant coatings was studied in detail. It was found that the glass-transition temperature (Tg) of the coatings was coincident with the baking temperature over the temperature range of 25 °C–220 °C for coatings being baked for just 20 min. However, the Tg reached a limiting value (about 240 °C) once the cross-linking reaction was complete, and would not increase further with the baking temperature. The peak temperature of the dimension versus temperature plots, where heat shrinkage occurred, was about a factor of 1.16 times higher than the baking temperature for the temperature range studied. Both the Tg and the shrinkage temperature were affected by the baking time. The thermal expansion coefficients (TEC), including the volumetric TEC (αv), the in-plane TEC (α1) and the out-of-plane TEC (α2), were measured by a pressure–volume–temperature (PVT) apparatus and thermal–mechanical analyzer (TMA). Great residual stress could be generated during the process, and the change in residual stress with the environmental humidity was investigated using vibrational holographic interferometry.
369 citations
TL;DR: An extensive literature review was performed to assemble data on the following properties: modulus, Poisson's ratio, tensile strength, compressive strength, viscosity, thermal expansion, density, permeability, melting temperature, heat of fusion, specific heat, thermal conductivity and thermal diffusivity.
367 citations
TL;DR: In this article, isolated graphene sheets were achieved by graphite intercalation and charge-induced exfoliation, and the resultant graphene oxide sheets were incorporated into polymer composites and thermal expansion was investigated by a thermo-mechanical analyzer.
Abstract: Isolated graphene sheets were achieved by graphite intercalation and charge-induced exfoliation. The resultant graphene oxide sheets were incorporated into polymer composites and thermal expansion was investigated by a thermo-mechanical analyzer. The test results indicated that inclusion of graphene into composites resulted in low coefficients of thermal expansion (CTEs), and increasing graphene fraction reduced CTEs more significantly. The 5 wt % graphene oxide-based composite shows 31.7% reduction below the glass transition temperature. Preliminary measurement of thermal conductivity also indicated that graphene composites significantly improved the thermal conductivity of polymer matrix. Thermal conductivity of 5% graphene composites showed about 4-fold increment in comparison to the polymer matrix. This finding will provide a solid foundation for graphene-enabled thermal management in microelectronics.
361 citations
TL;DR: This study designed and synthesized hyperbolic architectured ceramic aerogels with nanolayered double-pane walls with a negative Poisson’s ratio and a negative linear thermal expansion coefficient that display robust mechanical and thermal stability and are ideal for thermal superinsulation under extreme conditions, such as those encountered by spacecraft.
Abstract: Ceramic aerogels are attractive for thermal insulation but plagued by poor mechanical stability and degradation under thermal shock. In this study, we designed and synthesized hyperbolic architectured ceramic aerogels with nanolayered double-pane walls with a negative Poisson’s ratio (−0.25) and a negative linear thermal expansion coefficient (−1.8 × 10 −6 per °C). Our aerogels display robust mechanical and thermal stability and feature ultralow densities down to ~0.1 milligram per cubic centimeter, superelasticity up to 95%, and near-zero strength loss after sharp thermal shocks (275°C per second) or intense thermal stress at 1400°C, as well as ultralow thermal conductivity in vacuum [~2.4 milliwatts per meter-kelvin (mW/m·K)] and in air (~20 mW/m·K). This robust material system is ideal for thermal superinsulation under extreme conditions, such as those encountered by spacecraft.
352 citations