scholarly journals Effect of Equal Channel Angular Extrusion on the Thermal Conductivity of an AX52 Magnesium Alloy

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 497
Author(s):  
Zuzanka Trojanová ◽  
Kristýna Halmešová ◽  
Ján Džugan ◽  
Zdeněk Drozd ◽  
Peter Minárik ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Magnesium Alloy ◽  
Equal Channel Angular Extrusion ◽  
Light And Electron Microscopy ◽  
Processing Route ◽  
Flash Method ◽  
Nominal Composition ◽  
Microstructural Parameters ◽  
Angular Pressing

An AX52 magnesium alloy (nominal composition Mg-5Al-2Ca in w.%) was submitted to equal channel angular pressing (ECAP) using processing route A; 1–8 passes through the ECAP tool were applied. The thermal conductivity of the ECAP samples was measured using a flash method in the temperature interval from room temperature up to 350 °C. The microstructure and texture of the samples were studied by light and electron microscopy. The severe plastic deformation, realized by the ECAP, influences the thermal properties of the alloy. The possible microstructural parameters determining the thermal conductivity were analyzed. New dislocations, the grain, phase boundaries, and texture of the samples may perceptibly change the thermal properties.

scholarly journals Thermal characterization of the In–Sn–Zn eutectic alloy

10.30544/456 ◽  
2020 ◽  
Vol 25 (04) ◽  
pp. 325-334
Author(s):  
Dragan Manasijević ◽  
Ljubiša Balanović ◽  
Vladan Ćosović ◽  
Duško Minić ◽  
Milena Premović ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Melting Temperature ◽  
Latent Heat ◽  
Eutectic Alloy ◽  
Metallic Phase ◽  
Flash Method ◽  
Nominal Composition ◽  
Scanning Calorimetry ◽  
Latent Heat Of Melting

Thermal properties, including melting temperature, latent heat of melting, specific heat capacity and thermal conductivity, of a low-melting In–Sn–Zn eutectic alloy were investigated in this work. The In–Sn–Zn eutectic alloy with nominal composition 52.7In-44.9Sn-2.4Zn (at.%) was prepared by the melting of pure metals under an argon atmosphere. The conducted assessment consisted of both theoretical and experimental approaches. Differential scanning calorimetry (DSC) was used for the measurement of melting temperature and latent heat, and the obtained results were compared with the results of thermodynamic calculations. The measured melting temperature and the latent heat of melting for the In–Sn–Zn eutectic alloy are 106.5±0.1 °C and 28.3±0.1 Jg-1, respectively. Thermal diffusivity and thermal conductivity of the In–Sn–Zn eutectic alloy were studied by the xenon-flash method. The determined thermal conductivity of the investigated eutectic alloy at 25 °C is 42.2±3.4 Wm-1K-1. Apart from providing insight into the possibility for application of the investigated alloy as the metallic phase-change material, the obtained values of thermal properties can also be utilized as input parameters for various simulation processes such as casting and soldering.

Thermal Characterization of Carbon-Carbon Composites

2011 ◽  
Author(s):  
Messiha Saad ◽  
Darryl Baker ◽  
Rhys Reaves
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Critical Role ◽  
Carbon Composite ◽  
Flash Method ◽  
Carbon Composites ◽  
Energy Storage Devices ◽  
Graphitized Carbon

Thermal properties of materials such as specific heat, thermal diffusivity, and thermal conductivity are very important in the engineering design process and analysis of aerospace vehicles as well as space systems. These properties are also important in power generation, transportation, and energy storage devices including fuel cells and solar cells. Thermal conductivity plays a critical role in the performance of materials in high temperature applications. Thermal conductivity is the property that determines the working temperature levels of the material, and it is an important parameter in problems involving heat transfer and thermal structures. The objective of this research is to develop thermal properties data base for carbon-carbon and graphitized carbon-carbon composite materials. The carbon-carbon composites tested were produced by the Resin Transfer Molding (RTM) process using T300 2-D carbon fabric and Primaset PT-30 cyanate ester. The graphitized carbon-carbon composite was heat treated to 2500°C. The flash method was used to measure the thermal diffusivity of the materials; this method is based on America Society for Testing and Materials, ASTM E1461 standard. In addition, the differential scanning calorimeter was used in accordance with the ASTM E1269 standard to determine the specific heat. The thermal conductivity was determined using the measured values of their thermal diffusivity, specific heat, and the density of the materials.

Study on Thermal Conductivity of Polyetheretherketone/Thermally Conductive Filler Composites

2007 ◽  
Vol 124-126 ◽  
pp. 1079-1082 ◽  
Author(s):  
Sung Ryong Kim ◽  
Dae Hoon Kim ◽  
Dong Ju Kim ◽  
Min Hyung Kim ◽  
Joung Man Park
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Carbon Fiber ◽  
Conductive Filler ◽  
Laser Flash ◽  
Flash Method ◽  
Phase System ◽  
Two Phase ◽  
Nielsen Theory ◽  
Thermally Conductive

Thermal properties of PEEK/silicon carbide(SiC) and PEEK/carbon fiber(CF) were investigated from ambient temperature up to 200°C measured by laser flash method. Thermal conductivity was increased from 0.29W/m-K without filler up to 2.4 W/m-K with at 50 volume % SiC and 3.1W/m-K with 40 volume % carbon fiber. Values from Nielsen theory that predicts thermal conductivity of two-phase system were compared to those obtained from experiment.

scholarly journals Study of microstructure and thermal properties of as-cast high carbon and high chromium tool steel

10.30544/392 ◽  
2019 ◽  
Vol 25 (1) ◽  
pp. 1-10
Author(s):  
Dragan Miroslav Manasijevic ◽  
Žarko Radović ◽  
Nada Štrbac ◽  
Ljubiša Balanović ◽  
Uroš Stamenković ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Temperature Interval ◽  
Tool Steel ◽  
Room Temperature ◽  
Cold Work ◽  
Flash Method ◽  
Endothermic Effect ◽  
High Carbon ◽  
High Chromium

This work aims to investigate the microstructural and thermal properties of as-cast high carbon and high chromium cold work tool steel. The microstructure was investigated by using scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and X-ray diffraction (XRD) method. It was determined that at room temperature the microstructure of the investigated tool steel includes a lamellar network of M7C3 carbide precipitates along grain boundaries of ferrite grains in the base. Thermal diffusivity, specific heat capacity and thermal conductivity of the investigated steel alloy were determined in the temperature interval from 25 to 400 °C by using the laser-flash method. Thermal conductivity increases from 24.9 at 25 °C to 26.9 W/m·K at 400 °C. Phase transition temperatures in the temperature region from room temperature to 1250 °C were experimentally determined using differential scanning calorimetry (DSC). One endothermic effect in the temperature interval from 803 to 820 °C, corresponding to the ferrite/austenite phase transformation, was detected during sample heating. Experimental results were compared with the results of phase equilibria calculations obtained from the ThermoCalc software and TCFE6 database.

Thermal Properties of Carbon and Graphite Foams

2012 ◽  
Author(s):  
Melanie Patrick ◽  
Amber Vital ◽  
Darian Bridges ◽  
Messiha Saad
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Critical Role ◽  
Flash Method ◽  
Petroleum Pitch ◽  
Energy Storage Devices ◽  
Carbon And Graphite ◽  
Temperature Levels

Thermal properties such as specific heat, thermal diffusivity, and thermal conductivity of carbon and graphite foams are very important in the engineering design process and analysis of aerospace vehicles as well as space systems. These properties are also important in power generation, transportation, and energy storage devices including fuel cells. Thermal conductivity is the property that determines the working temperature levels of the material; it plays a critical role in the performance of materials in high temperature applications and it is an important parameter in problems involving heat transfer and thermal structures. The objective of this paper is to develop a thermal properties data base for carbon and graphite foams. Carbon foams are commercially produced from urethane, petroleum pitch-based and coal-based processes, and they typically have large pores (> 350 μm) and low density (< 1.0 g/cm3). Petroleum pitch-base and coal-base carbon/graphite foams can be tailored to be thermally conductive or thermally insulating. The thermophysical properties of carbon and graphite foams have been investigated using experimental methods. The flash method was used to measure the thermal diffusivity of the foams; this method is based on America Society for Testing and Materials standard (ASTM E1461). In addition, the Differential Scanning Calorimeter was used in accordance with the ASTM E1269 standard to measure the specific heat. The measured thermal diffusivity, specific heat, and density data were used to compute the thermal conductivity of the foams.

Laser Flash Measurement of Samples With a Transparent Reference Layer

2009 ◽  
Author(s):  
Heng Ban ◽  
Zilong Hua
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Temperature Response ◽  
Front Surface ◽  
Laser Flash ◽  
Laser Flash Method ◽  
Flash Method ◽  
Thermal Diffusivity Measurement ◽  
Reference Layer

The laser flash method is a standard method for thermal diffusivity measurement. This paper reports the development of a method and theory that extends the standard laser flash method to measure thermal conductivity and thermal diffusivity simultaneously. By attaching a transparent reference layer with known thermal properties on the back of a sample, the thermal conductivity and thermal diffusivity of the sample can be extracted from the temperature response of the interface between the sample and the reference layer to a heating pulse on the front surface. The theory can be applied for sample and reference layer with different thermal properties and thickness, and the original analysis of the laser flash method becomes a limiting case of the current theory with an infinitely small thickness of the reference layer. The uncertainty analysis was performed and results indicated that the laser flash method can be used to extract the thermal conductivity and diffusivity of the sample. The results can be applied to, for instance, opaque liquid in a quartz dish with silicon infrared detector measuring the temperature of liquid-quartz interface through the quartz.

scholarly journals Study of the Microstructure, Tensile Properties and Hardness of AZ61 Magnesium Alloy Subjected to Severe Plastic Deformation

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 776 ◽  
Author(s):  
Ondřej Hilšer ◽  
Stanislav Rusz ◽  
Pavel Szkandera ◽  
Lubomír Čížek ◽  
Martin Kraus ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Magnesium Alloy ◽  
Tensile Properties ◽  
Tensile Testing ◽  
Electron Backscatter Diffraction ◽  
Processing Route ◽  
Angular Pressing ◽  
Az61 Magnesium Alloy ◽  
Az61 Alloy ◽  
Average Grain Size

Hot extruded (EX) AZ61 magnesium alloy was processed by the twist channel angular pressing (TCAP) method, which combines equal channel angular pressing (ECAP) and twist extrusion (TE) processes and significantly improves the efficiency of the grain refinement process. Both the initial hot extruded AZ61 alloy and the alloy after completion of TCAP processing were examined by using optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD) and their corresponding micro-tensile testing (M-TT) and hardness testing at room temperature. The results showed that the microstructure of hot extruded alloy was refined well by TCAP due to dynamic recrystallization (DRX) caused by TCAP. The tensile properties, investigated by micro-tensile testing (M-TT), of the AZ61 alloy were significantly improved due to refined microstructure. The highest tensile properties including YS of 240.8 MPa, UTS of 343.6 MPa and elongation of 21.4% of the fine-grained alloy with average grain size below 1.5 µm was obtained after the third TCAP pass at 200 °C using the processing route Bc.

Thermal Property Measurements of Carbon Nanotube Forest Synthesized by Thermal CVD Process

2009 ◽  
Author(s):  
Qingjun Cai ◽  
Bing-chung Chen ◽  
Yuan Zhao ◽  
Julia Mack ◽  
Yanbao Ma ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Carbon Nanotube ◽  
Quartz Substrate ◽  
Laser Flash ◽  
Volume Density ◽  
Thickness Measurement ◽  
Flash Method ◽  
Thermal Cvd ◽  
3 Omega

Carbon nanotube (CNT) forest/cluster synthesized by a thermal CVD process has millimeter growth height, large porosity and nano level pore size, plus high thermal conductivity of individual CNT, thus it is potentially a good wick structure material in developing micro heat transfer devices. However, thermal properties, including effective thermal conductivity (ETC) of a bulky CNT layer, may not be as good as the common metallic wick materials. In this paper, a Netzsch DSC 404 C Pegasus is used for measurement of the CNT heat capacity. CNT volume density is obtained by measuring the ratio of a bulky CNT weight and volume. Both the laser flash and 3-omega measurement methods are employed to measure ETC for CNT wick structures synthesized by the thermal CVD processes. For the laser flash method, measurement deviations caused by reflective silicon and thin substrate are corrected by surface treatment and increased sample thickness. Measurement results of the laser flash indicate that a 600μm thick CNT layer has ETC varying from 0.7–1.2W/m.K. For the 3-omega approach, the measurement system is validated on a quartz substrate. However, the test results yield larger ETC on 250μm CNT samples. Geometric and one dimensional thermal conduction analysis indicate that the bulky CNT thermal properties are tied to CNT synthesis processes. ETC of bulky CNT layer can be enhanced by straightening CNT growth and increasing CNT growth volume density.

Thermal Characterization of IM7/8552-1 Carbon-Epoxy Composites

2014 ◽  
Author(s):  
Messiha T. Saad ◽  
Sandi G. Miller ◽  
Torrence Marunda
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Carbon Fiber ◽  
Specific Heat ◽  
High Performance ◽  
Critical Role ◽  
Flash Method ◽  
Handling Characteristics ◽  
Wide Range

Thermal properties of composite materials such as, thermal conductivity, diffusivity, and specific heat are very important in engineering design process and analysis of aerospace vehicles as well as space systems. These properties are also important in power generation, transportation, and energy storage devices including fuel cells. Thermal conductivity is the property that determines the working temperature levels of the material; it plays a critical role in the performance of materials in high temperature applications, and it is an important parameter in problems involving heat transfer and thermal structures. The objective of this paper is to develop a thermal properties data base for the carbon fiber-epoxy (IM7/8552-1) composite. The IM7 carbon fiber is a continuous, high performance, intermediate modulus, PAN based fiber. This fiber has been surface treated and can be sized to improve its interlaminar shear properties, handling characteristics, and structural properties. The 8552 is a high performance tough epoxy matrix for use in primary aerospace structures. It exhibits good impact resistance and damage tolerance for a wide range of applications. The IM7/8552-1 is an amine cured unidirectional prepreg. The manufacturer recommended cure cycle for this material was followed, which includes consolidation under vacuum and autoclave pressure. The composite has a service temperature up to 121°C (250°F). The thermal properties of IM7/8552-1 carbon-epoxy have been investigated using experimental methods. The flash method was used to measure the thermal diffusivity of the composite. This method is based on the American Society for Testing and Materials standard, ASTM E1461. In addition, the Differential Scanning Calorimeter was used in accordance with the ASTM E1269 standard to measure the specific heat. The measured thermal diffusivity, specific heat, and density data were used to compute the thermal conductivity of the IM7/8552-1 carbon-epoxy composite.

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