Session: 14-01: Measurement Techniques and Thermophysical Properties in Micro/Nanoscale

Paper Number: 132676

132676 - Experimental Study of Thermal Conductivity and Interfacial Thermal Resistance in Single Microparticle 

Abstract: 

Microparticles have great application potential in the fields of energy, biologic medicine and environment. Recently, the application of microparticles tends to be composite to improve synergistic effect between different samples, which helps to explore more special function. For most particle composites, the research of heat transfer is of great significance for their own applications. However, the heat transfer of particle composites is affected by many aspects, such as intrinsic thermophysical properties of different single microparticles and the thermal contact interface between microparticles. For a long time, the intrinsic thermophysical properties of single microparticle and the influence of thermal contact between microparticles are difficult to obtained. Most studies have been only conducted on compacted powders or single microparticle placed on a certain carrier. The internal microscopic heat transfer mechanism of particle composites cannot be explained deeply. The reason is that the micrometer scale size of a single microparticle makes measurement inconvenient. In addition, the contact size between different single microparticles is even smaller and more difficult to measure. 

Based on the above, it is particularly important to develop an efficient experimental system that can measure the heat transfer performance of single microparticles. At present, microscale thermal measurement methods mainly include microdevice method, T-type method, 3ω method and H-type method. These methods are commonly used for low-dimensional material measurement. The single microparticle measurement is rarely reported. 

In this study, we successfully bonded single microparticles onto the H-type device through a simple micro-transfer technology. Independent thermophysical property measurements of one or more single microparticles were achieved. Through experimental and theoretical analysis, the thermal conductivity of single microparticles of four different materials and the interfacial thermal resistance between polymethyl methacrylate (PMMA) particles were obtained. The experimental results are in good agreement with the empirical values of thermophysical parameters of each material. It provides a set of effective experimental methods for the study of heat transfer mechanism of composite materials at the microscopic level.

During the measurement process, the heat was transferred from one nanowire to another nanowire through the intermediate sample. The thermal conductivity of the sample determines the amount of heat transferred. Therefore, if the temperature rise of two nanowires can be measured, the thermal conductivity of the sample to be measured can be obtained through subsequent numerical calculation. According to the thermal resistance calculation formula and the device model, the sample thermal resistance and the contact thermal resistance between sample and the nanowire can be obtained. After obtaining the above parameters, the interfacial thermal resistance between two microparticles can be calculated by measuring two bonded microparticles. 

According to the experimental results, the thermal conductivity of the microparticles to be measured has a certain variation trend with the change of temperature. Taking PMMA as an example, we measured its thermal conductivity at different sizes. The thermal conductivity value of PMMA microparticles is in the range of 0.15 W·m^-1·K^-1 to 0.45 W·m^-1·K^-1. It increases first and then decreases with the increase of temperature. The temperature point of the highest thermal conductivity is related to the crystal structure of different samples. The thermal resistance value shows a nearly linear growth trend with increasing size before the glass transition. The contact thermal resistance between microparticle and nanowire is about 4×10^-6 K·m²·W^-1. By measuring two bonded microparticles, the interfacial thermal resistance values between microparticles are 19.33×10^-6 K·m²·W^-1 and 16.5×10^-6 K·m²·W^-1 at 313K and 333K. Through analysis, the uncertainty of this experiment is about 3.4%.

Presenting Author: Jie Zheng Tsinghua University

Presenting Author Biography: Jie Zheng is currently working toward the Ph.D. degree in Power Engineering and Engineering Thermophysics at Tsinghua University, Beijing, China. Her main research topic is measurement of thermophysical properties of materials.

Authors:

Jie Zheng Tsinghua University
Haidong Wang Tsinghua University