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16XV International Symposium on Self-Propagating High-Temperature Synthesis
INFLUENCE OF ADDITIVES ON PHYSICO-MECHANICAL PROPERTIES OF HIGH STRENGTH ALUMINOSILICATE REFRACTORY SHS MATERIALS
R. D. Kapustin
Merzhanov Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, Chernogolovka, Moscow, 142432 Russia *e-mail: kapustin-roman@mail.ru
DOI: 10.24411/9999-0014A-2019-10056
Currently, there are the following major global trends in the production of refractory materials:
- increasing requirements for quality and durability of materials;
- the use of highly pure and synthetic raw materials;
- an increase in the share of unburned unshaped refractories in the total volume of production (up to 50% of the total production of refractories and more) which reduces the complexity of work and reduces the cost of repairs;
- development of new materials and technologies for their production to increase the life of thermal units and reduce the cost of repair work.
This paper is devoted to the study of physicomechanical properties and refractoriness of new modifications of unshaped refractory materials with improved physicochemical, mechanical and performance characteristics. The purpose of the work is to determine the properties of new refractory materials and to identify the most promising of them for the manufacture of products exposed to direct exposure to ultra-high temperatures, torch torches, etc. based on experimental studies. Obtaining refractories with higher characteristics and higher temperature of application will significantly increase the resistance of such problematic elements of furnaces as burner stones, baffles, and beams. The experimental research method involved the preparation of samples from refractory ceramic materials, their firing up to T = 1600°C, followed by the study of their physicomechanical characteristics and structural changes.
At the first stage of the experiments, corundum materials were investigated, including using electrowelled corundum and high-purity AhO3. Samples were also made of tabular corundum, which is coarse-grained granules calcined at 1950°C. Such corundum is called "tabular" (lamellar), since its crystals have a lamellar form and size from 50 to 150 ^m. In addition, samples were made of electrocorundum with microfiber additives: basalt and carbon. At the second stage of the experiments corundum materials with the addition of periclase (MgO) were investigated. These samples were also subjected to heat treatment at a maximum temperature of 1600°C (Fig. 1).
Fig. 1. Microstructure of unshaped corundum refractory material after heat treatment at 1600°C.
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R. D. Kapustin
ISHS 2019 Moscow, Russia
As part of the work, the evaluation of the strength properties of all the materials under investigation, including after heat treatment at various temperatures, was carried out. Changes in the structure of materials when exposed to different temperatures were also investigated.
As a result of experimental studies of the samples it was found:
- products from unshaped refractory materials based on AhO3 (electrocorundum) are able to work at temperatures of at least 1600°C without melting and destruction. Moreover, as a result of exposure at high temperatures and synthesis of new compounds, their strength properties and wear resistance are significantly increased;
- linear thermal shrinkage of corundum unshaped refractories (tabular, electrofused or ultrapure corundum) at temperatures up to 1600°C is about 6-7%;
- the introduction of carbon microfiber allows to reduce the mass and density of corundum refractories, but at the same time there is an increase in linear thermal shrinkage up to 9% at 1600°C due to fiber burnout;
- the introduction of periclase into corundum refractories of about 5-10 wt % allows to reduce the linear thermal shrinkage at 1600°C to 2%;
- the strength of corundum and corundum-periclase refractories after heat treatment at 1600°C, as a rule, increases by 35-50%. In addition, a significant increase in wear resistance and resistance to mechanical stress.
R. D. Kapustin
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