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The application of coatings based on graphite in ferrous metallurgy

Intensification of the steelmaking process in the metallurgical aggregates created extremely harsh conditions for the service of the refractory lining at the point of direct contact with the liquid metal and slag. The destruction of the lining due to a number of chemical and physical reasons, the main of which is the corrosive effect of the slag and gas environment, erosion, liquid and solid phases, as well as extremely high temperatures, as a result, the rate of chemical reactions between the refractory and the aggressive environment increases exponentially.

Fundamentally, the solution to the problems increasing the resistance of the lining is based on high quality refractory materials, which theoretically has high refractory properties and a certain structure that prevents the penetration of liquid and gaseous phases in the working area of the refractory. In particular, the use of the cleanest and fused oxides of magnesium, aluminum, alumomagnesium spinel, as well as compositions of these materials in various ratios with carbon. The carbon prevents the penetration of slag into the refractory, which is associated, primarily, with its low wettability with slag, as well as the ability to restore the iron oxides in the slag, while increasing the viscosity and the melting point of the slag. In addition, gaseous products of carbon oxidation are filling existing pores and create excess pore pressure, preventing the penetration of slag.

The prospect of the possibility of its application on the working surface of the refractory protective coatings, possessing all the positive qualities of carbon and at the same time having high mechanical characteristics, including maximum adhesion to the surface of the refractory and high abrazivostruynoy, formed the basis of our work on obtaining graphitemoderated coatings on refractory materials operating in contact with liquid metals and slags.

For this purpose our enterprisethe first was developed by high performance dispersant, allowing to obtain a suspension of the so-called "active graphite" with a particle size down to 0.3 nm. The quality of preparation of such suspensions depends on many factors explain them in this work, we did not.

We have chosen and investigated the compositions of graphite coatings for the protection of the working surface of steel pouring ladles (on magnesia-carbon bricks) and protection corundum covers thermocouples to monitor the temperature of the casting in prakovce. Studied the mechanism of graphite coatings in various conditions and identified ways to develop these coatings for their use as protection of refractory materials for use in demanding environments.

Industrial tests were conducted with graphite coating on steel-teeming ladles of OAO "MMK", where the resulting increase in the resistance of the lining to 10%. Also, it was found more than three-fold increase of resistance corundum covers for thermocouples at the Seversky pipe plant.

Work continues on the creation of the graphite coatings with additives of titanium carbide, obtaining graphite coatings with a tensile compressive strength of not less than 200 N/mm2 and a shear strength of at least 40 N/mm2.

We see great potential in the application of coatings of this type as in metallurgy and mechanical engineering. In case of interest of our potential customers, potential collaboration on the selection of the optimal protective coatings for various purposes.

The abstract of the report published in the journal "New Ogneupory", No. 3, 2011