Nanomaterials in refractory technology

Abstract

A short review is presented of prospects for using nanomaterials in various refractory technologies, and an estimate is given of existing and future directions of their use for improving the operating properties of refractories. The possibility of controlling material properties at the atomic level makes it possible to create new innovative refractory materials and technology.The main stimulus in the development of the contemporary refractory industry is improvement of existing and the development of new high-temperature technology with even more severe specifications for refractory operating conditions, i.e. temperature, chemical erosion, mechanism, etc.Here the task of improving the service properties of refractories is inseparably connected with the question of reducing the cost of production, observation of ecological standards, the possibility if utilizing waste products, and recycling refractories.The requirement for finding comprehensive solutions has led to use in the majority of heating units, in particular ferrous metallurgy, of complex multicomponent composite materials, including oxide ceramics, metals and carbon. During the last thirty years significant success has been achieved in optimizing the physicochemical properties and chemical composition of these refractories for specific operating conditions. Currently the main areas of development include a change-over to controlling the refractory properties for an evermore finer size level, since the microstructure of any material is mainly determined by occurrence within it of different physicochemical processes.In view of this use in refractories of highly-(0.1 -1 mm) and nanodispersed (10 -100 nm) systems with a controlled composition and morphology is very important. In fact, the refractory branch, for tens of years and thousand of tons of consumed technical grade carbon (soot) and silica (microsilica, aerosil) is already one of the largest world users of nanomaterials. Development of new refractory technology has a favorable effect on formation of the market for new industrial nanomaterials, stimulating an increase in the volume of their production and a reduction cost.Interest in this class of materials is due to the possibility of a marked change in properties of normal substances by converting them to a nanosize condition [1]. An increase in the relative proportion of atoms or molecules, that are at the surface of particles, leads to an increase in the contribution of surface energy in practically all physicochemical processes of nanodispersed system reaction with the surroundings. Such a change, important from the point of view of dispersed refractory systems, may be a reduction in the melting and sintering temperatures, an increase in chemical activity and the rate of occurrence of chemical reactions, the possibility of preparing alloys, compounds and composites, impossible in traditional materials from a thermodynamic point of view. In turn, an increase in the relative interphase surface of bulky compacted refractories leads to a marked impro...

In depth studies on cementitious nanocoatings on graphite for its contribution in corrosion resistance of alumina based refractory composite

“…In CaAl 2 O 4 , bands below 250 cm À 1 are relevant to translational modes of Ca 2 þ [32]. A group of bands at around 150 cm À 1 can therefore be attributed to Ca-O bonds whereas for the signals below 300 cm À 1 , the vibrations can be related to AlO 4 5 À and Ca 2 þ ions [28]. That paper also confirmed some carbonated phases below 1100 cm À 1 due to formation of hemi-and mono-carboaluminates by exposure to CO 2 .…”

“…strength, density, resistance to thermal shock, corrosion etc. Recent literatures clarify how introduction of nanoscale materials in refractory composite enhances the surface energy, controls the rate of chemical reaction and modifies the surface and interfaces of bulk [2][3][4][5]. Selective application of nanodimensional materials thus firmly stands as a prerequisite for obtaining user friendly refractory ceramics.…”

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“…This nanostructure has found more applications such as in synthesis of flame retardants (Chen and Wang 2010;Kiliaris and Papaspyrides 2010), mineral UV filter in sunscreens (Popov et al 2005;Sadrieh et al 2010) and self-cleaning products (tiles, windows and textiles) like antifogging car mirrors and dental mirror surfaces (Funakoshi and Nonami 2007;Veronovski et al 2009). Another emerging application of nanostructure is in the field of refractory technologies, for example, in the steel and cement industries (Kuznetsov et al 2010;Antonovič et al 2010).…”

Nanotechnology for Chemical Engineers

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