Abstract

To address two important challenges in aerospace industry which are 1) ice growth and 2)
friction and wear, two environmentally friendly materials such as hexagonal boron nitride (hBN)
and antifreeze protein (AFP) were pursued in this study. Molybdenum disulfide (MoS2)-based
solid lubricants commonly doped with lead (Pb) are widely used in industry. However, due to the
toxic nature of Pb, there is an interest in replacing it with more environmentally friendly material.
hBN is a potential alternative with a lamellar structure and a great lubricity property. Therefore,
MoS2-based solid lubricant containing five different concentrations of hBN (3.8, 5.7, 7.5, 9.5, and
11.5 wt.%) were applied on five 304L stainless steel substrates using spray bonding method to
explore their tribological performance. Reciprocating tribology tests were performed using a ball-
on-flat tribometer with alumina (Al2O3) counterface in atmospheric conditions. To characterize the
wear tracks, ex-situ analysis such as Scanning Electron Microscopy (SEM), Raman spectroscopy,
and Atomic Force Microscopy (AFM) were used. The MoS2-based solid lubricant with 5.7% hBN
revealed acceptable tribological performance. Additionally, to study the amount of ice growth on
a surface, atomistic molecular dynamics (MD) simulations were performed for three systems;
system A contains 3-layer hBN nanosheet, a layer of ice, and spruce budworm antifreeze protein
(sbwAFP), system B consist of 3-layer hBN nanosheet, an ice layer, and a non-antifreeze protein
found in Mycobacterium tuberculosis (MfpA), and system C includes 3-layer hBN nanosheet and
an ice layer without any biomolecules. The presence of sbwAFP and hBN presented less formation
of hexagonal ice in system A and C compared to system B.