High-throughput measurements of thermal conductivity and the coefficient of thermal expansion. Xuan Zheng

ISBN: 9781109028461

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High-throughput measurements of thermal conductivity and the coefficient of thermal expansion.  by  Xuan Zheng

High-throughput measurements of thermal conductivity and the coefficient of thermal expansion. by Xuan Zheng
| NOOKstudy eTextbook | PDF, EPUB, FB2, DjVu, AUDIO, mp3, ZIP | 98 pages | ISBN: 9781109028461 | 10.27 Mb

This dissertation presents the development and application of spatially-resolved measurement techniques for high-throughput studies of thermal conductivity and the coefficient of thermal expansion (CTE). Time-domain thermoreflectance (TDTR) has beenMoreThis dissertation presents the development and application of spatially-resolved measurement techniques for high-throughput studies of thermal conductivity and the coefficient of thermal expansion (CTE). Time-domain thermoreflectance (TDTR) has been used for micron-scale thermal conductivity measurements.

Time-domain probe beam deflection (TD-PBD), developed in this dissertation, has been used to measure the CTE and, in some cases, Youngs modulus with micron-scale spatial resolution. TDTR measurements provide thermal transport property information for the analysis of TD-PBD data.-Localized thermal conductivity measurements of electron-beam physical vapor deposited 8wt% yttria-stabilized zirconia (YSZ) coatings show that the thermal conductivity for heat flow along both the through-thickness and in-plane directions is isotropic and uniform throughout the depth of the YSZ coating.

After 500 furnace cycles, the thermal conductivity in the in-plane direction increases from 1.84 +/- 0.08 W m-1 K-1 to 2.2 +/- 0.2 W m-1 K-1.-High-throughput thermal conductivity measurements of binary Ni solid solutions in a diffusion multiple provide large amounts of thermal conductivity data for Ni(Cr), Ni(Pd), Ni(Pt), Ni(Rh) and Ni(Ru) solid solutions.

These data are used to test the applicability of the Smith-Palmer equation and the Wiedemann-Franz law for Ni alloys. After subtracting the lattice component calculated by molecular dynamics simulations from the total thermal conductivity, the electronic thermal conductivity of pure Ni is 25% smaller than that predicted from the Wiedemann-Franz law.

With the addition of solutes of Pt and Rh, the deviation from the Wiedemann-Franz law decreases. However, the negative deviation of the electronic thermal conductivity of Ni(Pd) alloys from the Wiedemann-Franz law increases slightly to 29% at a Pd concentration of 40 at.%. The Smith-Palmer equation is not a reliable method for predicting the thermal conductivity of Ni solid solution alloys from measurements of the electrical conductivity.-High-throughput CTE measurements are performed on a Fe-Ni diffusion couple to find the Invar composition and test the effect of ion irradiation on CTE.

The CTE of Fe-Ni alloys with Ni concentration between 30 at.% and 37 at.% increases upon 2.3-MeV Ar+ irradiation. At the Invar composition Fe65Ni35, the CTE increases from 0.5 x 10-6 K-1 before ion irradiation to 2.4 x 10-6 K -1, 3.0 x 10-6 K-1 and 4.3 x 10 -6 K-1 for ion doses of 0.01, 0.03, and 0.1 displacement per atom, respectively. The increase in CTE is created by the decrease in atomic short-range order upon ion irradiation.-TDTR and TD-PBD are used to study the local properties near the dentin-enamel junction (DEJ) in a human tooth. The thermal conductivity and Youngs modulus are uniform in dentin and enamel, respectively, and change abruptly across the dentin-enamel interface.

The CTE changes gradually in dentin near the DEJ over a transition width of &ap- 100 mum.



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