Nanoparticles reinforced ceramic bonds derived from K-gel geopolymers composites at elevated temperature: Pore structure, micro and meso scale properties

Abstract

The refractory alkaline activated materials gained attention in the various engineering and industrial applications due to its environmental and eco-friendly benefits. The present study deals with the evaluation of the effects of nano-ZrO2, nano-Al2O3, and nano-TiO2 particles reinforcement mechanism on the final properties of the geopolymer matrices subjected to thermal treatment from 900 to 1250°C. Three series of composite matrices were obtained by adding 2–8 wt% of nanoparticles content (Al2O3, TiO2 and ZrO2) within the activated mortar and were devoted RAi, RRi and RZi (i = 2, 3, 5 and 8%).The designed composite matrices were characterized using several analytical methods and techniques including the mechanical characterization, mercury intrusion porosimetry (MIP) as well as the microstructural characterization. The results revealed that the use of the high content of nanoparticles (8 wt%) favored formation of a cross-linkage chain around the crystalline phases present within matrices. Their resulting percolation-induced reinforcement acted as supplementary with the interlocked network from the crystalline phases within the matrices to rendering it denser and compact. The matrices with high content of the nanoparticles added exhibited high mechanical properties at 1250°C. Flexural strength and young modulus were 70.7, 52 and 78.4 MPa, and 28.15, 22.61 and 29.86 GPa for RA, RR and RZ series respectively. Furthermore, the formation of the new crystalline phase like cordierite, mullite and leucite contributed to hindering the crack propagation within the matrices and increased the level of crystallization of the matrices by providing a homogeneous and well-dispersed structure. The produced matrices emerged stable at high temperature treatment and therefore could be used as a potential candidate for the materials for elevated temperatures applications.