I-Corps: Scalable Development of Multifunctional Hexagonal Boron Nitride Protective Coatings

William Marsh Rice University, Houston TX

Investigators

Abstract

The broader impact/commercial potential of this I-Corps project is the development of a protective coating for energy conservation and emission reduction. Multifunctional protective coating materials and processes are urgently needed to alleviate the problem of ineffective coating technologies. For example, heating, ventilation and air conditioning (HVAC) systems costs can represent more than 50% percent of a building’s energy consumption, yet the high cost of maintenance and corrosion of commercial HVAC units are often overlooked. Humidity and exposure to pollutants like hydrocarbons are major causes of corrosion, commonly observed on the heat exchanger coils from HVAC systems. When corrosion sets in, the operating efficiency can soon be reduced by 50-70%, and unit life halved. This will progressively increase energy bills, discharge of CO2, and health risks for occupants. Current epoxy-based coatings are thick polymers with low thermal conductivity, which commonly act as an insulating layer and inevitably reduce the heat exchange efficiency by up to 15%. Moreover, epoxy coatings are neither flexible nor UV resistant. Eventually, they tend to peel off or disintegrate, which leaves the coils unprotected from corrosion damage. The proposed hexagonal boron nitride (hBN) protective coating may increase heat exchange by 70%, and add elevated anti-corrosion, anti-abrasion properties to HVAC systems to survive harsh working environments reducing energy costs and emissions. This I-Corps project is based on the development of a scalable chemical-assisted ball-mill process for large-scale production of ultra-fine hexagonal boron nitride (hBN) nanosheets. The hBN nanosheet is an electrically insulating and thermally conductive layered material with excellent thermal and chemical stabilities making it a promising anti-corrosion, anti-oxidation, anti-wear, as well as anti-erosion coating additive. The manufacturing process starts with HBN powder, the polymer deformation and sheer force resulting from collision facilitate the exfoliation of commercial bulk hBN. The process has the additional advantage of being able to integrate optional chemicals during ball-milling, which could provide hBN with designated chemical functionalities. In addition, thin hBN flakes may be further integrated into continuous film on various industrial substrates using existing coating techniques, such as vapor deposition and spray coating. Successful development of the proposed technology may significantly improve coating performance and provide a process for integrating materials into a protective coating on different industrial substrates. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.