Experimental thermal property data of the Sony US‐18650 lithium‐ion battery and components are presented, as well as thermal property measuring techniques. The properties in question are specific heat capacity false(Cpfalse) , thermal diffusivity (α), and thermal conductivity (k), in the presence and absence of electrolyte [1 M LiPF6 in ethylene carbonate‐dimethyl carbonate EC:DMC, 1:1 wt %)]: The heat capacity of the battery, Cp , is 0.96±0.02Jg−1 K−1 at an open‐circuit voltage (OCV) of 2.75 V and 1.04±0.02Jg−1 K−1 at 3.75 V. The thermal conductivity, k, was calculated from k≡αρCp where α was measured by a xenon‐flash technique. In the absence of electrolyte, k increases with OCV, for both the negative electrode (NE) and the positive electrode (PE). For the NE, the increase is 26% as the OCV increases from 2.75 to 3.75 V, whereas for the PE the increase is only 5 to 6%. The dependence of both Cp and k on OCV is explained qualitatively by considering the effect of lithiation and delithiation on the electron carrier density, which leads to n‐type semiconduction in the graphitic NE material, but a change from semiconducting to metallic character in LixCoO2 PE material. The overall effect is an increase of Cp and k with OCV. For k this dependence is eliminated by electrolyte addition, which, however, greatly increases the effective k of the layered battery components by lowering the thermal contact resistance. For both NE and PE, the in‐plane k value (measured along layers) is nearly one order of magnitude higher than the cross‐plane k. This is ascribed mostly to the high thermal conductivity of the current collectors and to a lesser extent to the orientation of particles in the layers of electrodes. © 1999 The Electrochemical Society. All rights reserved.

Thermophysical properties were investigated for zirconium diboride (ZrB 2 ) and ZrB 2 -30 vol% silicon carbide (SiC) ceramics. Thermal conductivities were calculated from measured thermal diffusivities, heat capacities, and densities. The thermal conductivity of ZrB 2 increased from 56 W (m K) À1 at room temperature to 67 W (m K) À1 at 1675 K, whereas the thermal conductivity of ZrB 2 -SiC decreased from 62 to 56 W (m K) À1 over the same temperature range. Electron and phonon contributions to thermal conductivity were determined using electrical resistivity measurements and were used, along with grain size models, to explain the observed trends. The results are compared with previously reported thermal conductivities for ZrB 2 and ZrB 2 -SiC.

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Improvement in the thermal conductivity of aluminumhigh thermal conductivity. AlN in a "pure" form is not only difficult to densify by pressureless sintering but also has a nitride (AlN) can be realized by additives that have a high low thermal conductivity. Densification of AlN can be easily thermodynamic affinity toward alumina (Al 2 O 3 ), as is facilitated by adding a variety of oxides (and, in some cases, clearly demonstrated in the aluminum nitride-yttria (AlNnon-oxides) as sintering aids. Rare-earth and/or alkaline-earth Y 2 O 3 ) system. A wide variety of lanthanide dopants are oxides are often added as sintering aids. 6-26 The addition of compared at equimolar lanthanide oxide:alumina (Ln 2 O 3 :sintering aids has a dual purpose: it aids in densification and Al 2 O 3 , where Ln is a lanthanide element) ratios, with enhances the thermal conductivity of the AlN-grain-boundary- samaria (Sm 2 O 3 ) and lutetia (Lu 2 O 3 ) being the dopants thatoxide-phase composite. The role of additives in enhancing thergive the highest-and lowest-thermal-conductivity AlN commal conductivity can be understood, considering the effect of posites, respectively. The choice of the sintering aid and the various parameters on thermal conductivity (in particular, the dopant level is much more important than the microstrucrole of impurities). ture that evolves during sintering. A contiguous AlN phaseThe principal impurity in AlN is oxygen. The phase diaprovides rapid heat conduction paths, even at short sintering gram 27 between AlN and alumina (Al 2 O 3 ) shows the existence times. AlN contiguity decreases slightly as the annealing times of a spinel structure with the approximate formula Al 3 O 3 N. increase in the range of 1-1000 min at 1850؇C. However, aAlN powders invariably contain some Al 2 O 3 on the surface, substantial increase in thermal conductivity results, because which spontaneously forms when AlN powder is exposed to air. of purification of AlN grains by dissolution-reprecipitationIn addition, some oxygen also is present in the AlN lattice in a and bulk diffusion. Removal of grain-boundary phases, dissolved form. Oxygen that has dissolved in the AlN lattice is with a concurrent increase in AlN contiguity, occurs at high essentially present as Al 2 O 3 that has dissolved in the lattice. As annealing temperatures or at long times and is a natural suggested by Slack and coworkers, 28,29 the most plausible mode consequence of high dihedral angles (poor wetting) in liquidof oxygen (or Al 2 O 3 ) incorporation into the AlN lattice is by the phase-sintered AlN ceramics.formation of aluminum vacancies. The corresponding defect reaction may be given as 28,29 I. IntroductionA LUMINUM NITRIDE (AlN), as a substrate material in elecwhere V Al denotes a vacant aluminum site. Mass and strain tronic packaging, has attracted considerable attention over misfits caused by the vacant aluminum site increase the scatterthe last two decades, because of its excellent properties, which ing cross section of phonons, which decreases the phonon ...

To reduce the uncertainty of build performance in metal additive manufacturing, robust process monitoring systems that can detect imperfections and improve repeatability are desired. One of the most promising methods for in situ monitoring is thermographic imaging. However, there is a challenge in using this technology due to the difference in surface emittance between the metal powder and solidified part being observed that affects the accuracy of the temperature data collected. The purpose of the present study was to develop a method for properly calibrating temperature profiles from thermographic data to account for this emittance change and to determine important characteristics of the build through additional processing. The thermographic data was analyzed to identify the transition of material from metal powder to a solid as-printed part. A corrected temperature profile was then assembled for each point using calibrations for these surface conditions. Using this data, the thermal gradient and solid-liquid interface velocity were approximated and correlated to experimentally observed microstructural variation within the part. This work shows that by using a method of process monitoring, repeatability of a build could be monitored specifically in relation to microstructure control.

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