Winter weather can wreak havoc on communities experiencing snow and ice. Ice especially can be very disruptive, halting airline traffic, stopping wind turbines, and downing power lines. Carbon nanotubes (CNTs) have been used previously as heaters in laboratory experiments. However, these may not scale well to large surface areas, need to be combined with other materials, or may not be suitable to apply in the field as a retrofit solution. We explore a method that functionalizes carbon nanomaterials that can be spin coated to produce a transparent heater. 

Carbon nanomaterials like CNTs, graphene, or carbon nanofibers are carbon structures with a length scale under 100 nanometers. These materials generally have high electrical conductivity, which may make them inadequate choices for electrical heating applications. In order to lower their conductivity, the materials were chemically treated with strong sulfonating acids, such as sulfuric acid (fuming) and chlorosulfonic acid in presence of 1-pyrenebutyric acid or 1-pyrenemethylamine hydrochloride at room temperature and neutralized using ammonium hydroxide. As carbon nanomaterials in solution tends to agglomerate together to form larger clusters due to high van der Waals interactions, the tested solution was centrifuged at 5,000 rpm to remove large particles and to concentrate the solution. The solution was then spin coated onto hydrophilic glass slides. The electrical connection was constructed by application of the silver paint after multiple layers of the solution were applied. Several materials and performance characteristics of the coated glass slides were investigated, including resistance, Raman spectroscopy, optical transmittance, and thermal imaging.

Raman spectroscopy confirmed the presence of functionalized groups, which affected the conductivity of the carbon nanomaterials. Resistance measurements also showed a variation of resistance based on the number of applied layers. Test samples with fewer coated layers showed resistance that was too high to have any electrical conductions. With increased number of coated layers, the percolation threshold was reached and temperatures went up over 115 C under 30 seconds, with more than 50% transmittance for all samples. 

Applications of this study include de-icing of car or aircraft windows, rotor blades, turbine blades, aircraft leading edges. The goal is to move from spin coating to spray coating so that this solution can then be applied in the field to existing structures.


Functionalizing Carbon Nanomaterials for Transparent Heaters

Division / Sponsors: 
Heat Transfer Division (HTD), Fluids Engineering Division (FED)

Heat Transfer Summer Conference
Paper Proceedings: https://asmedigitalcollection.asme.org/HT/HT2020/volume/83709

18th International Conference on Nanochannels, Microchannels, and Minichannels
Paper Proceedings: https://asmedigitalcollection.asme.org/ICNMM/ICNMM2020/volume/83693

Fluids Engineering Division Summer Meeting
Paper Proceedings: https://asmedigitalcollection.asme.org/FEDSM/FEDSM2020/volume/83716

HT-ICNMM2020 - Virtual Conference, SHTC - Virtual Conference, FEDSM2020 - Virtual Conference

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