Study of SiO₂ coating and carboxylic surface-modification on Mg-based inorganic fiber by one-step reflux reaction

Magnesium hydroxide sulfate hydrate (5 Mg(OH)₂·MgSO₄·3H₂O abbreviated 513MHSH) whiskers using for fiber reinforcements and fillers are synthesized via a reflux reaction by using MgO and H₂SO₄ as reactants. In general, the 513MHSH whiskers have hydrophilic surface and heat resistant property with crystal water molecules. In this work, surface modification and SiO₂ coating technique were employed for various application by coating with organic and silica layer on 513MHSH whisker surface. Also, SiO₂ coating system is important for preventing aggregation and enhancing thermal stability [J Kor Ceram Soc 55:618, 2018; J Nanosci Nanotechnol 10:380, 2010]. Controlling pH value acts as important factor for establish one-step process that synthesis and surface modification/SiO₂ coating process simultaneously to improve the efficiency in terms of the time and process. The morphology and phase of synthesized 513MHSH whiskers are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Surface modified whiskers were characterized by Fourier transform infrared spectroscopy (FTIR) and the thermal stability of SiO₂ coated whiskers were evaluated by thermogravimetric analysis (TGA).