Preparation and Surface Modification of Magnesium-Based Sound Absorbing Materials Via a Low-Temperature Vapor Deposition

The poor durability of lightweight cement due to hydrophilic property and porous microstructure limits its extensive application. In this study, a superhydrophobic magnesium-based sound absorbing materials (Mg-SAM) have been prepared using basic magnesium sulfate cement as the matrix material and then modified by a low-temperature vapor deposition (LTVD). The results reveal that an ultrathin film of perfluorodecyltriethoxysilane (PFDTS) can be gently deposited on the surface of Mg-SAM with a water contact angle higher than 150° via a low temperature (65 °C) heating process. The modification mechanism of LTVD can be described as the formation of a self-assembled fluorine-containing film through the condensation reaction between silanols and the hydroxyl groups on the surface of Mg-SAM. The noise reduction coefficient and mechanical strength of Mg-SAM with a density of 280 kg·m−3 reach 0.7 and 1.8 MPa respectively without any change after LTVD treatment. This facile, low-cost LTVD technique is a promising approach for large-scale modification of porous materials.