Highly concentrated ceramic binder suspensions (HCBS). Raw materials, properties, and classification (Review)

Abstract

Various casting systems are flnding an ever-increasing application in ceramics and refractory technology and, also, direct applications in metallurgy [i]. They are employed not only for forming products using casting techniques, but also for conducting the processes of ceramic mass preparations, synthesis of ceramic raw materials, granulation of powders, and for obtaining refractory concretes, different coatings, mortars and renders, and certain composite materials.In recent years, there has been intensive research for developing ceramic binders and the materials based on them. Ceramic binders (binding agents) are obtained based on highly concentrated and stabilized polydispersed systems whose dispersion (dispersing) media include inorganic acids and chlorides (or sols). The latter ones form directly during the process of obtaining the suspension owing to the interaction of phases. As a rule, in this case, catalysts of dissolution are introduced into the system. Setting (hardening) and strengthening of the ceramic binders are mainly based on the polycondensation phenomena. In this case, the strength properties of the material are determined by the composition of the dispersion medium, the surface condition and the degree of dispersion of the particles of the solid phase, their stacking density in the material, and the regimes and the conditions of strengthening.Application of the binding properties of the ceramic suspensions and the strengthening effect in the semifinished products based on them made it possible to work out the principles of the technology of new types of ceramic materials possessing improved service properties: high-density cast refractories having a granular structure, unfired ceramics, refractory concretes (ceramic concretes),and numerous highlyporous materials. In this case, all typesof these refractories can be produced using widely occurring materials (siliceous, chamotte, and high-alumina materials).The technology of HCBS is based on the fundamental principles initially proposed and developed in connection with the technology of quartz ceramics [2][3][4]. The production technology of strong high-density semifinished products (.porosity of the casting Pcas up to 9-12%, the ultimate bend strength Obnd up to 3-7.5 N/mm 2) was described in detail almost two decades ago [3,4]. This paper presents the first analytical review of the data generated during the last two decades in the field of HCBS with regard to the compositions of the investigated HCBS, the general characteristics of the processes, and the technological parameters used for their production. This work made it possible to carry out the first classification of HCBS on the basis of the factor of the chemical nature of their solid phase.Basic Characteristics. When formulating the problem of production and application of HCBS based on different materials, it was assumed that there is a regular relationship between the chemical nature of the solid phase, the production technology, the state of the dispersion medium in the system (fixed a...

HCBS ceramic concretes in the XXI century — problems and prospects for applying technology in the field of silicate materials science. Part 1

“…3, 36, 44]. The main research for preparing HCBS and specimens of building materials based on them was carried out on Aragats pearlite, containing 77% SiO 2 , 15% Al 2 O 3 , 4.1% Na 2 O; Dm cal = 4.2% [30,44]. The efficiency of this material in HCBS technology for producing relatively cheap building materials consisted of the fact that under stable uniform conditions the rate of its grinding is significantly higher (by a factor of 2 -3) than for quartz sand.…”