Cement-Free Refractory Concretes. Part 3. Very Fine Forms of Silica as Effective Refractory Concrete Components
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Vol. 61, No. 1, May, 2020
SCIENTIFIC RESEARCH AND DEVELOPMENT CEMENT-FREE REFRACTORY CONCRETES. PART 3. VERY FINE FORMS OF SILICA AS EFFECTIVE REFRACTORY CONCRETE COMPONENTS1 Yu. E. Pivinskii2,3 Translated from Novye Ogneupory, No. 1, pp. 28 – 38, January, 2020.
Original article submitted September 18, 2019. Matrix systems of many types of cement-free refractory concretes (CFRC) have a certain content of highly dispersed components of silica composition, i.e., silica sols, SiO2 nanoparticles (in HCBS of different compositions), as well as fine silica (“microsilica” MS). The degree of their dispersion and hydration (lyophilic nature), determined by their specific surface, is considered. It is shown that the dispersion medium of HCBS containing SiO2 is a relatively concentrated silica sol. With respect to hydrophilic and colloidal chemical characteristics, SiO2 nanoparticles in HCBS with comparable dispersion are similar to ordinary silica sols. The advantage of SiO2 nanoparticles in HCBS compared with silica sols is that they are characterized by polydispersion (from 5 – 10 to 100 nm) and purer chemical composition. As a rule silica sols contain 0.2 – 0.4% Na2O. Compared to CFRC based on a silica binder the advantage of using HCBS as a ceramic concrete matrix system is that it contains all components in an optimum ratio, i.e., not only binders in the form of nanoparticles and a micro-filler (as an MS analog) in the form of particles 0.1 – 2.0 mm, but also polydispersed particles (1 – 100 mm) of corundum or high alumina composition. Keywords: cement-free refractory concretes (CFRC), matrix system, HCBS, silica sol, ceramic concrete, bonded water, nanoparticles, microsilica (MS), quartz glass.
about nano-silica have been provided in monographs [1, 2]. Production aspects of using nano-dispersed silica applied to nano-technology in the field of silicate materials has been considered in reviews [3 – 6]. It should be noted that currently nano-dispersed SiO2 is a leader in the world market for nano-materials [1, 2]. In publications there is extensive understanding of “colloidal silica”, and it has been presented in an Ailer monograph [7] as stable dispersions or sols consisting of discrete amorphous particles. Silica hydrosols and nano-dispersed oxide systems whose extensive use is due to the polymeric nature of particles, presence of a highly developed surface, and functional (silanol) groups. With respect to the degree of significance at the level of practical implementation of technology for preparing silica sols or silica hydrosols there is apparently a clearer example of nano-technology in the field of inorganic materials science [1 – 5]. The present article considers aspects of using different forms of very fine silica in order to prepare predominantly
From the point of view of prospects for developing different areas in the field of creating technology and producing inorganic materials (including CFRC) using various forms of silica SiO2 a very important situation is that silicon after oxygen is the second elemen
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