CC BY
14XV International Symposium on Self-Propagating High-Temperature Synthesis
HEAT-RESISTANT PHOSPHATE MATERIALS IN SELF-PROPAGATING EXOTHERMIC SYNTHESIS MODE
Ch. G. Pak", V. M. Batrashov*", G. A. Koshkin", and K. V. Sokolova"
aPenza State University, Penza, 440026 Russia * e-mail: shift150887@mail.ru
DOI: 10.24411/9999-0014A-2019-10116
The most time-consuming and energy-intensive operation of modern production of heat-resistant materials with application temperatures of up to 1700°C is the use of materials drying and firing processes. In addition, the manufacturing technology of such materials provides for a limited range of products. The self-propagating exothermic synthesis of heat-resistant materials allows to avoid unnecessary energy consumption, as well as to obtain products with enhanced physicomechanical and heat-resistant properties of various geometric shapes and sizes [1]. The technology is based on conducting an exothermic reaction between dispersed aluminum and phosphate binder [2]. The filler in this system can serve as refractory and refractory powders. including industrial waste. The production technology of heat-resistant materials in the exothermic reaction mode can be represented by the following scheme: X + Y + Z = N, where X is liquid phosphate binders system; Y is metal or alloy of metals or their mixture; Z is refractory filler of aluminosilicate composition, alumina, high alumina oxides, fibers, mixtures of oxides; N is synthesis product.
At present, self-hardening heat-resistant materials of aluminophosphate, aluminochromophosphate, aluminomagnesium phosphate, aluminosilicophosphate, magnesium phosphate composition with average density of 400-1000 kg/m3, application temperature above 1770°C [3] have been obtained by self-propagating exothermic synthesis.
Controlling the formation of physicomechanical and heat-resistant properties of materials is possible by controlling the process of structure formation of materials, which in turn can be achieved in several ways [4]:
- change in the reaction exotherm (change in the ratio of the liquid and solid phases of the original system, the use of phosphate binders of varying degrees of substitution, the controlled amount and dispersion of aluminum powder, the use of heating and cooling of the initial mixture);
- synthesis of materials in a limited formwork under gas pressure or in vacuum;
- material formation by layered synthesis.
The possibility of material formation by layer-by-layer synthesis opens up an interesting direction for the development of heat-resistant phosphate materials—obtaining materials of varying density. Figure 1 shows the main types of heat-resistant materials of variable density.
(a) (b) (c)
Fig. 1. Phosphate heat-resistant material of variable density: (a) aluminum powder PAP-1 is represented as the aluminum component; (b) modified aluminum powder POS-15 is presented as an aluminum component; (c) as an aluminum component, PA-4 aluminum powder is presented.
iSHS 2019 Moscow, Russia
A feature of the materials obtained is the process of obtaining products in the mode of self-propagating exothermic synthesis. In the macrostructural analysis of the obtained materials, 3 zones are clearly visible: 1 zone is pressed phosphate material with a spherical aluminosilicate filler; 2 zone is intermediate structure; 3 zone is cellular phosphate heat-resistant material.
1. A.G. Merzhanov, Self-propagating high-temperature synthesis of refractory compounds, Bull. USSR Acad. Sci., 1976, no. 10.
2. A.N. Abyzov, Obtaining heat-insulating heat-resistant phosphate materials by the method of self-propagating synthesis, Heat-resistant materials and concrete, Chelyabinsk, UralNIIstromproekt, 1978.
3. V.A. Abyzov, A.N. Abyzov, Cellular heat-resistant concretes based on phosphate binders and aggregates from aluminum production and processing wastes, Refract. Tech. Ceram., 2015, nos. 4-5, pp. 69-73.
4. V.A. Grachev, A.Y. Rozen, C.G. Pak, V.M. Batrashov, SHS technology for development of high-temperature thermal insulation composite, J. Ind. Pollut. Control, 2017, vol. 33, no. 1, pp. 824-833.
