Prevention of spontaneous combustion of cellulose with a thin protective Al2O3 coating formed by atomic layer deposition

Abstract We have studied properties of thin protective coating layers of Al 2 O 3 , grown by atomic layer deposition (ALD) technique on surfaces of cellulose fibrous materials, using scanning electron microscopy (SEM), scanning transmission microscopy (STEM), energy dispersive x-ray spectroscopy (EDS), high-resolution transmission microscopy (HR-TEM), x-ray diffraction (XRD) and thermal gravimetry (TGA). A minimum thickness of about 50 nm was required to completely inhibit oxygen diffusion into the material and prevent self-ignition at elevated temperatures. No substantial differences were found in morphology or protection performance of Al 2 O 3 coatings produced by thermal or plasma-enhanced ALD (PEALD) methods. However, PEALD technique has shown almost a double growth rate, while, at the same time, it was successfully applied at temperatures as low as 40 °C without degrading quality of the coating.