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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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Journal ArticleDOI
TL;DR: In this article, a functionally graded material (FGM) part was fabricated by depositing a Cu-based alloy on top of a high strength low alloy (HSLA) steel by twin-wire and arc additive manufacturing (TWAAM).

92 citations

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the temperature distribution during laser exposure and the threshold temperature by analyzing the volume of the modification based on a thermal diffusion model and found that threshold temperature becomes lower with increasing laser exposure time.
Abstract: Accumulation of thermal energies by highly repeated irradiation of femtosecond laser pulses inside a glass induces the heat-modification whose volume is much larger than that of the photoexcited region. It has been proposed that the heat-modification occurs in the region in which the temperature had overcome a threshold temperature during exposure of laser pulses. In order to understand the mechanism of the heat-modification, we investigated the temperature distribution during laser exposure and the threshold temperature by analyzing the volume of the modification based on a thermal diffusion model. We found that the threshold temperature becomes lower with increasing laser exposure time. The dependence of the threshold temperature on the laser exposure time was explained by the deformation mechanism based on the temperature-dependent viscosity and viscoelastic behavior of a glass under a stress loading by thermal expansion. The deformation mechanism also could simulate a tear-drop shape of a heat-modification by simultaneous double-beams’ irradiation and the distribution of birefringence in a heat-modification. The mechanism proposed in this study means that the temperature-dependence of the viscosity of a glass should be essential for predicting and controlling the heat-modification.

92 citations

Journal ArticleDOI
TL;DR: In this paper, a double-ceramic-layer (DCL) thermal barrier coating (TBC) with high-entropy rare-earth zirconate (HE-REZ) as the top layer and yttria stabilized Zirconia (YSZ), as the inner layer sprayed on Ni-based superalloy by atmospheric plasma spraying was reported.
Abstract: We report a double-ceramic-layer (DCL) thermal barrier coating (TBC) with high-entropy rare-earth zirconate (HE-REZ) as the top layer and yttria stabilized zirconia (YSZ) as the inner layer sprayed on Ni-based superalloy by atmospheric plasma spraying. La2Zr2O7 (LZ) was selected as a reference for the HE-REZ. Thermal cycling test results demonstrate that the HE-REZ/YSZ DCL coating exhibited obviously improved thermal stability when compared to the LZ/YSZ DCL coating. The reasons for the improvement of the thermal shock resistance are considered to be the anti-sinterability of the HE-REZ ceramics during the thermal cycling test attributed to the sluggish diffusion effect and as well as the better match in the coefficient of thermal expansion of HE-REZ coating with the YSZ inner layer. In addition, the HE-REZ coating maintains fluorite structure after thermal cycling test. This study makes one step forward in the development and application of high-entropy rare-earth zirconate ceramic thermal barrier coatings.

92 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of the main alloying elements Si, Cu and Ni on the thermal properties of hypoeutectic and near-eutective Al-Si foundry alloys is described.
Abstract: In this study we describe the effect of the main alloying elements Si, Cu and Ni on the thermal properties of hypoeutectic and near-eutectic Al–Si foundry alloys. By means of systematic variations of the chemical composition, the influence of the amount of ‘second phases’ on the thermal conductivity, thermal expansion coefficient, and thermal shock resistance is evaluated. Thermodynamic calculations predicting the phase formation in multi-component Al–Si cast alloys were carried out and verified using SEM, EDX and XRD analysis. The experimentally obtained data are discussed on a systematic basis of thermodynamic calculations and compared to theoretical models for the thermal conductivity and thermal expansion of heterogeneous solids.

92 citations

Journal ArticleDOI
TL;DR: In this article, a geometrical model for trioctahedral micas has been applied to predict the structural changes of a synthetic fluorphlogopite, KMg3(Si3AI)OIoF2, as a function of temperature and these are compared with observed structural parameters determined at 700°C.
Abstract: A geometrical model structure for trioctahedral micas has been applied to predict the structural changes of a synthetic fluorphlogopite, KMg3(Si3AI)OIoF2, as a function of temperature and these are compared with observed structural parameters determined at 700°C. The model employs the cell dimensions measured as a function of temperature, the bond lengths determined at room temperature and thermal expansion coefficients of the bond lengths determined in previous studies. The predicted tetrahedral rotation angle, c~, suggests that the silica oxygen ring about the potassium becomes more nearly hexagonal at higher temperatures. The mode of expansion of the Mg octahedron changes at about 400°C, whereafter the octahedron tends to become elongated along the normal to the layer formed by the octahedra. This change in the mode of expansion corresponds to the observed kink in the linear expansivities of the cell dimensions. The predicted parameters have been confirmed by a structure refinement on data collected at 700°C. The observed ~ (3 ~) and octahedral flattening angles for magnesium (58.0 °) and for potassium (56.5 °) at 700 °C agree with the predicted values. The very large expansion coefficient of the K-O bond length accounts for large linear expansivity along c.

92 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023603
20221,249
2021683
2020742
2019759
2018767