Session: 11-45-01: Technique development for thermophysical characterization

Paper Number: 111923

111923 - Rapid Cross-Plane Thermal Conductivity Characterization From Data Automation and System Miniaturization 

This work describes a novel low-cost system for measuring the thermal conductivity of material and coatings on small bulk scale layered samples. The system implements ISO 8301:1991 and ASTM C518-21 by means of a thermoelectric heat flow meter to provide rapid thermal characterization measurements of material samples. This device provides a compact measurement system, fitting into a 200 mm × 300 mm footprint, with small-scale capabilities, making it useful for developing coatings and integrating new materials in multiscale designs.

The determination of properties such as transverse thermal conductivity in coatings and similar planar structures is important for advancing work in new material coating and metamaterials research. Hence, the need for reliable measurements, additionally the automation of measurement systems provides an opportunity to collect mass amounts of data to characterize materials. However, most commercial systems that measure thermal conductivity require large samples for accurate readings and are expensive, with costs ranging from $10,000-$100,000. Therefore, this system aims to solve the price and size constraints with a single unit that cost around $2,400. In addition to utilizing commonly available lab infrastructure.

The system utilizes low-cost commercial off-the-shelf components to provide heating, cooling, and temperature control. A KHLVA-101/10-P OMEGA Engineering resistive heater is used for heating, while cooling is done using a Peltier type electrical cooler with an aluminum heat sink and fan attached. The system utilizes an OMEGA K-type Fast Response Thermocouple to read the temperature directly off the two surfaces and uses an MCP9600 thermocouple amplifier to convert the analog voltage data into a digitized value. The system also minimizes the effects of any other form of heat transfer, other than conduction, by enclosing the bed in a sealed sample area where samples are set up on an insulated test bed. The greenTEG gSKIN®-XP heat flux sensor is used with a Keithley DMM6500 6.5 digital multimeter to measure the total amount of heat flux transferred through the material, allowing the system to back out the thermal properties of the tested samples.

Testing was done on two types of samples, a set of insulative materials and a set of conductive materials. Both the insulative and conductive materials tested were compared to their textbook values and gave average errors of 0.97% and 4.26% respectively. These errors result show close agreement between the tested materials and their expected thermal conductivity values based on literature. In addition, the standard deviation of the insulative material was 0.02, while conductive materials had a standard deviation of 11.61. These show a good agreement in reproducing the thermal conductivity of different materials of similar characteristics.

In addition, to demonstrating the system's capabilities to determine thermophysical properties of materials, the system has also been shown to determine the thermal resistance of different coatings on material substrates. This was shown by measuring the change in thermal conductivity of a polycarbonate substrate coated in various materials, preliminary results show agreement with expected change.  The system’s automation capability to measure and process thermophysical data has proven its ability to provide rapid and robust materials characterization of samples. Leading to a simple process used to collect and process data for evaluating new materials.  Overall, this novel low-cost system represents a significant advancement in the field of material science. Particularly, at its low price point it allows for more accessible testing or material characterization for various researchers and research entities; potentially leading to impact various industries, including packaging, electronics, and energy.
 

Presenting Author: Matthew Nakamura University of Hawaii at Manoa

Presenting Author Biography: Matthew Nakamura is currently a Ph.D. candidate under the supervision of Dr. Joseph Brown in the Nanosystems lab in the Department of Mechanical Engineering at the University of Hawaiʻi at Mānoa. Matthew Received his B.S. degree in Mechanical Engineering in 2020 from the University of Hawaiʻi at Mānoa and his M.S. degree as one of the first participants in the departments Bachelors-and-Masters combined degree pathway program in 2021. His work has included design of low-cost sensing systems and apparatuses, more recently in the area of multiscale and EM metamaterial.

Authors:

Matthew Nakamura University of Hawaii at Manoa
Kailer Okura University of Hawaii at Manoa
Andrea Murillo University of Hawaii at Manoa
Joseph Brown University of Hawaii at Manoa