Preparation and microstructure analysis of fly ash continuous fiber

A new type of inorganic fiber-fly ash continuous fiber was innovatively developed in this study to alleviate the problems of low comprehensive utilization rate and lacking of high-value utilization means of industrial solid waste fly ash. The melt flow temperature and macro-mechanical properties of different samples were studied. The results showed that with the increase in acidity coefficient index (M_K), the melt flow temperature decreased first and then increased, and the lowest value was 1340 °C when M_K was 3.1. Meanwhile, with the gradual increase in M_K, the tensile strength and elastic modulus of monofilament increased first and then decreased. When the M_K was 3.8, the tensile strength and elastic modulus of fiber monofilament reached 2064 MPa and 16.7 GPa, respectively. According to the results of XRD, TG-DSC, FTIR and SEM microstructure analysis methods, it is found that the macro-mechanical properties of fibers are closely related to the chemical composition and phase structure evolution of raw materials. After melting at high temperature, the samples with high M_K form a dense three-dimensional glassy network structure, which leads to the higher mechanical strength of the fibers. However, in the samples with lower M_K, the vitreous network structure is loose, which reduces the mechanical properties of the fiber. Finally, the M_K range (2.5–3.8) for preparing high-performance fly ash fiber was proposed in this paper. In this range, the synthesized fly ash continuous fiber has low melting temperature and excellent mechanical properties, which has a potential of industrial application.