Date of download: 10/14/2017 Copyright © ASME. All rights reserved. From: Measurement of Interface Thermal Resistance With Neutron Diffraction J. Heat Transfer. 2013;136(3):031302-031302-12. doi:10.1115/1.4025500 Figure Legend: Schematic of traditional apparatus for measuring thermal contact resistance. In the current technique, the thermocouples are replaced by collimated neutron diffraction measurements (adapted from Ref. [9]).

Date of download: 10/14/2017 Copyright © ASME. All rights reserved. From: Measurement of Interface Thermal Resistance With Neutron Diffraction J. Heat Transfer. 2013;136(3):031302-031302-12. doi:10.1115/1.4025500 Figure Legend: Schematic of the overall experimental geometry (a), and the central strip within which the internal temperatures are measured via neutron diffraction. Figures 2(c) and 2(d) depict the expected temperature distribution for finite interface resistances and the equivalent resistance circuit, respectively.

Date of download: 10/14/2017 Copyright © ASME. All rights reserved. From: Measurement of Interface Thermal Resistance With Neutron Diffraction J. Heat Transfer. 2013;136(3):031302-031302-12. doi:10.1115/1.4025500 Figure Legend: Sample stack mounted on the Vulcan diffractometer. The welded membrane covers the cooling serpentine through which liquid nitrogen is circulated. The system is held together with spring-loaded struts at four corners. Figure 3(b) shows the thermocouple placement. Thermocouple pairs TC3-TC4 and TC5-TC8 yield the temperature gradient in the middle-plate.

Date of download: 10/14/2017 Copyright © ASME. All rights reserved. From: Measurement of Interface Thermal Resistance With Neutron Diffraction J. Heat Transfer. 2013;136(3):031302-031302-12. doi:10.1115/1.4025500 Figure Legend: The temperatures recorded from thermocouples TC3-TC8 in the middle-plate as a function of time, for hot-plate set-points of 343 K (a) and 293 K (b), respectively. These data were correlated with thermal strain measurements to define the precision of the temperatures determined from neutron thermal strains. The corresponding mean temperatures after stabilization are 344.6 ± 0.2 K and 296.6 ± 0.1 K.

Date of download: 10/14/2017 Copyright © ASME. All rights reserved. From: Measurement of Interface Thermal Resistance With Neutron Diffraction J. Heat Transfer. 2013;136(3):031302-031302-12. doi:10.1115/1.4025500 Figure Legend: Temperatures recorded from thermocouples TC0-TC9 as a function of time, with the hot-plate controller set-point at 323 K and liquid nitrogen introduced into the heat-sink. The temperature range of Fig. 5(a) is 3.5× of Fig. 5(b).

Date of download: 10/14/2017 Copyright © ASME. All rights reserved. From: Measurement of Interface Thermal Resistance With Neutron Diffraction J. Heat Transfer. 2013;136(3):031302-031302-12. doi:10.1115/1.4025500 Figure Legend: Schematic of the neutron diffraction geometry. The probe volume is defined by the intersection of the apexes of the acceptance cones of the radial collimators and the incident beam. The sample can be moved along three orthogonal directions so that any position within the sample stack can be interrogated (inset).

Date of download: 10/14/2017 Copyright © ASME. All rights reserved. From: Measurement of Interface Thermal Resistance With Neutron Diffraction J. Heat Transfer. 2013;136(3):031302-031302-12. doi:10.1115/1.4025500 Figure Legend: Typical time-of-flight (TOF) neutron diffraction data from the central plate refined via the GSAS program [40]. The measured data are depicted by the “+” symbols. The solid trace is the intensity computed from the refined model. The difference between the refined model output and the measured values form the residual line. In this plot, the tick-marks indicate the TOF positions of Bragg reflections.

Date of download: 10/14/2017 Copyright © ASME. All rights reserved. From: Measurement of Interface Thermal Resistance With Neutron Diffraction J. Heat Transfer. 2013;136(3):031302-031302-12. doi:10.1115/1.4025500 Figure Legend: Neutron diffraction measurements of the Al lattice spacing as a function of position through the center of the stack at room temperature (RT) equilibrium and at steady state with thermal gradient. The error bars associated with the data points are similar in size to the symbols. The gaps in the data for the heat-sink plate correspond to the hollowed-out region where the coolant serpentine had been machined. The data for the cold-plate reflect the presence of additional residual strains due to the machining and welding steps. These strains did not change during the measurements. Typical error associated with each data point is ±0.0002 Å.

Date of download: 10/14/2017 Copyright © ASME. All rights reserved. From: Measurement of Interface Thermal Resistance With Neutron Diffraction J. Heat Transfer. 2013;136(3):031302-031302-12. doi:10.1115/1.4025500 Figure Legend: Variation of the linear coefficient of thermal expansion, α, of the Al plates with temperature for the four expressions used in modeling. The boiling temperature of liquid nitrogen (77 K) is marked as the lower bound of temperature range.

Date of download: 10/14/2017 Copyright © ASME. All rights reserved. From: Measurement of Interface Thermal Resistance With Neutron Diffraction J. Heat Transfer. 2013;136(3):031302-031302-12. doi:10.1115/1.4025500 Figure Legend: abaqus model of the Al plate stack at steady state. The inset shows the interface detail on the heat-source side.

Date of download: 10/14/2017 Copyright © ASME. All rights reserved. From: Measurement of Interface Thermal Resistance With Neutron Diffraction J. Heat Transfer. 2013;136(3):031302-031302-12. doi:10.1115/1.4025500 Figure Legend: Variation of thermal strain with x-position for stacks with full (a) and partial (b) nitrogen flow. In these figures, the lines connecting the data points are from the finite element simulation. The average temperature values in each plate are shown in Table 1. The error in the strain values is smaller than ±30 microstrain, which is comparable to the symbol size in the graph.

Date of download: 10/14/2017 Copyright © ASME. All rights reserved. From: Measurement of Interface Thermal Resistance With Neutron Diffraction J. Heat Transfer. 2013;136(3):031302-031302-12. doi:10.1115/1.4025500 Figure Legend: Modeled temperature values within the stack as a function of (k_I/k_M). In the calculation, the effective interface thickness was conservatively assumed to be 2 μm, which is twice the experimentally measured maximum asperity height.

Date of download: 10/14/2017 Copyright © ASME. All rights reserved. From: Measurement of Interface Thermal Resistance With Neutron Diffraction J. Heat Transfer. 2013;136(3):031302-031302-12. doi:10.1115/1.4025500 Figure Legend: Computed thermal conductivity across the 25 mm thick Al middle-plate as a function of the variables (kI/kM) and tI. For hot and cold boundary temperatures of 306 K and 112 K, complete, intermediate and negligible thermal conductivities occur in regions I, II, and III (depicted by the in-set schematics). For 2 μm thick (identical) interfaces, the (ΔTM)A-E corresponding to the marked points A to E in Region II are 1.2, 11, 74, 167, and 191 K, respectively for ΔTHC = 194 K.