Cement-free refractory castable. Part 3. Highly dispersed types of silica as effective components of castable

Abstract

The matrix systems of many types of cement-free refractory castable (CFRC) are characterized by a certain content of highly dispersed components of silica composition — silica sols, SiO 2 nanoparticles (in HCBS of different compositions), as well as dispersed silica («microsilicon» ― MS). The degree of their dispersion and hydration (lyophilicity), determined by their specific surface, is considered. It was shown that the dispersion medium of HCBS containing SiO 2 is a relatively concentrated silica sol. According to their hydrophilic and colloidal chemical characteristics, SiO 2 nanoparticles in HCBS with comparable dispersion are similar to ordinary silica sols. The advantage of SiO 2 nanoparticles in HCBS compared with silica sols is that they are characterized by polydispersity (from 5‒10 to 100 nm) and a purer chemical composition. Silica sols, as a rule, contain 0,2‒0,4 % Na 2 O. Compared to CFRC on a silica binder, the advantage of using HCBS as a matrix system of ceramic concrete is that it contains all components in an optimal ratio ― not only binders in the form of nanoparticles and a micro-filler (as an analogue of MS) in the form of particles 0,1‒2,0 μm, but also polydisperse particles (1‒100 μm) of corundum or high alumina composition. Ill. 7. Ref. 44.