Extending Cooling Rate Performance of Fast Scanning Chip Calorimetry by Liquid Droplet Cooling

Evgeny Zhuravlev,Jing Jiang,Christoph Schick,René Androsch,Dongshan Zhou

doi:10.3390/app11093813

Abstract

The liquid droplet cooling technique for fast scanning chip calorimetry (FSC) is introduced, increasing the cooling rate for large samples on a given sensor. Reaching higher cooling rates and using a gas as the cooling medium, the common standard for ultra-fast temperature control in cooling requires reducing the lateral dimensions of the sample and sensor. The maximum cooling rate is limited by the heat capacity of the sample and the heat exchange between the gas and the sample. The enhanced cooling performance of the new liquid droplet cooling technique is demonstrated for both metals and polymers, on examples of solidification of large samples of indium, high-density polyethylene (HDPE) and poly (butylene 2,6-naphthalate) (PBN). It was found that the maximum cooling rate can be increased up to 5 MK/s in room temperature environment, that is, by two orders of magnitude, compared to standard gas cooling. Furthermore, modifying the droplet size and using coolants at different temperatures provide options to adjust the cooling rate in the temperature ranges of interest.

Highlights

The option of fast cooling is important for the analysis of crystallization and vitrification of materials, as it allows for designing specific solidification pathways, including crystallization at high melt–supercooling or full suppression of crystallization [1]
In the case of fast scanning chip calorimetry (FSC), the cooling of nanogram-size samples is possible with rates up to 107 K/s [8]
The cooling performance is significantly improved by using liquid droplet cooling and synchronous switching off the heater, as illustrated in Figure 6a on the example of an empty

Summary

Introduction

The option of fast cooling is important for the analysis of crystallization and vitrification of materials, as it allows for designing specific solidification pathways, including crystallization at high melt–supercooling or full suppression of crystallization [1]. In the case of metal alloys, the critical cooling rate, avoiding the precipitation of alloying elements on cooling, is of particular importance for optimizing the age hardening processes, needed for understanding precipitation kinetics (commonly from 0.5 to 1000 K/s) [2,3]. There are two ways to reach high cooling rates for fast scanning chip calorimetry (FSC). In the case of fast scanning chip calorimetry (FSC), the cooling of nanogram-size samples is possible with rates up to 107 K/s [8]. Rapid cooling of larger samples is possible with a cooling medium with a higher thermal effusivity, e.g., using a liquid or solid as a heat sink instead of a gas

Results

Discussion

Conclusion