Effect of TiO2 addition on sintering, microstructure and properties of anorthite-based ceramics derived from reduced copper slag

Reduced copper slag is a promising substitute constituent in anorthite-based ceramics. To reduce the sintering temperature of this type of slag-derived ceramics, the role of TiO2 addition in the sintering, microstructure, physical and mechanical properties, and environmental and appearance performance was studied by experimental and theoretical methods. The results show that the Ti element was dissolved in the glassy phases and anorthite crystals instead of producing new phases. This behavior allows the liquid appearance at earlier tem-peratures and accelerates the ion diffusion, thus significantly enhancing the sintering and contributing to a dense microstructure with fine closed pores. Besides, this improvement is achieved at a relatively slight sacrifice of anorthite grains. The addition of 4 wt% TiO2 results in a decrease in the vitrification temperature by 100 oC and an enhancement of flexural strength by 50%. Moreover, the slag-derived ceramics show extremely low leaching toxicity and a relatively higher whiteness, ensuring the cleanliness and quality of anorthite-based ceramics. However, the ceramics show lower bulk density and obvious surface defects with the TiO2 content up to 6 wt%.