Controlling the Thermal Stability of Kyanite-Based Refractory Geopolymers.

Juvenal Giogetti Nemaleu Deutou,Elie Kamseu,Vincenzo M Sglavo,Rodrigue Cyriaque Kaze

doi:10.3390/ma14112903

Abstract

The present project investigated the thermal stability of cold-setting refractory composites under high-temperature cycles. The proposed route dealt with the feasibility of using fillers with different particle sizes and studying their influence on the thermo-mechanical properties of refractory geopolymer composites. The volumetric shrinkage was studied with respect to particle sizes of fillers (80, 200 and 500 µm), treatment temperature (1050–1250 °C) and amount of fillers (70–85 wt.%). The results, combined with thermal analysis, indicated the efficiency of refractory-based kyanite aggregates for enhancing thermo-mechanical properties. At low temperatures, larger amounts of kyanite aggregates promoted mechanical strength development. Flexural strengths of 45, 42 and 40 MPa were obtained for geopolymer samples, respectively, at 1200 °C, made with filler particles sieved at 80, 200 and 500 µm. In addition, a sintering temperature equal to 1200 °C appeared beneficial for the promotion of densification as well as bonding between kyanite aggregates and the matrix, contributing to the reinforcement of the refractory geopolymer composites without any sign of vitrification. From the obtained properties of thermal stability, good densification and high strength, kyanite aggregates are efficient and promising candidates for the production of environmentally friendly, castable refractory composites.

Highlights

Rapid global population growth and industrialization often conflict with sustainable development and pollution, and environmental drawbacks are typically associated with industrial processes
The objective of the present study was to investigate the possibility for metakaolin, calcined bauxite, calcined talc and kyanite sieved at 80, 200 and 500 μm to be the raw materials for refractory geopolymers heated at high temperatures (1050, 1150, 1200 and 1250 ◦ C)
It was noticed that the amount of fine kyanite particles influenced the mass loss (Figure 1b), with a larger kyanite amount corresponding to better thermal stability

Summary

Introduction

Rapid global population growth and industrialization often conflict with sustainable development and pollution, and environmental drawbacks are typically associated with industrial processes. This applies to the refractory sector, characterized by worldwide production of around 35–40 million tons per year [1,2,3], with applications in industrial sectors including metallurgy, cement kilns, energy treatment and recovery and energy production [4,5,6,7]. Global Status), in 2015, the global industrial sector (e.g., Magnesia Spinel Brick Production for production of magnesia refractory raw materials) accounted for 39% of worldwide energy consumption and 21% of total greenhouse gas emissions. The performance (mechanical, thermal stability, crystallography, etc.)/energy cost ratio is a key indicator to successfully reduce environmental impact, avoiding the outgrowth of emissions that may arrive as a result of increased material requirements

Objectives

Methods

Results

Conclusion