Microstructure Analysis and Hardness Test of Geopolymer Based Nano-Composite Materials

Objectives: The aim of this study was to analyse and characterize microstructure of self-synthesis geopolymer based nano-composite materials and to test its hardness.
Methods: This laboratory experimental study used four types of self-synthesis inorganic fillers (alumina, magnesia, silica, and zirconia) using sol-gel technique, combine with geopolymer matrix of two different alkali activator concentrations (8 M and 12 M), and characterized its microstructure using X-Ray Diffraction (XRD). Six specimens of nanocomposite bars (20 x 5 x 2 mm) were divided into two groups based on different alkali activator concentration tested using Vickers hardness testing machines and analysed its microstructure morphology using scanning electrone microscope (SEM). The difference in hardness between the groups was analyzed with two-way ANOVA followed by a Tukey test.
Results: XRD result shows ceramics metal oxides were formed in nano sizes crystal orde have different cistalinity structure (Al₂O₃, MgAlO₄, SiO₂, ZrO₂). Vickers hardness test showed higher hardness was achieved in nanocomposite with alkali activator 12 M (13,1 VHN). SEM images of geopolymer based nanocomposite shows more homogenity on groups with 8 M alkali activator and more nanorods filler on groups with 12 M alkali activator.
Conclusions: Geopolymer based Mg-Al-Si-Zr nanocomposite can be synthesized using sol-gel technique, alkali activator 12 M was found to increase hardness of the material as it accelerate reaction, however more study required for its application in dentistry.