Research for the influence of organicinorganic modifiers of phenolformaldehyde resin on the physical and mechanical properties of magnesiacarbon refractories

The conditions for the existence and development of metallurgical enterprises and the ceramic industry today compel the search for technological solutions for the development of new types of refractory and ceramic materials, as well as materials science approaches for their design. Magnesia­carbon refractories meet contemporary operational demands for metallurgical units as lining materials due to their thermal stability, resistance to the destructive effects of molten metals, and constant or increasing strength with rising temperatures. To enhance strength parameters, a design approach is employed to create a reinforcing phase within the matrix of magnesia­carbon material. This phase is synthesized at elevated temperatures by implementing conditions favorable for its formation and by modifying phenol­formaldehyde resin during raw material preparation. The physic­mechanical properties of non­sintered magnesia­carbon refractories were investigated using various types of modifiers (nickel sulfate, ETS­40, citric acid, and ammonium oxalate) introduced into the phenol­formaldehyde resin. The study demonstrated the feasibility of modifying PFR to improve the strength of non­sintered magnesia­carbon materials and confirmed the necessity of introducing hexamethylenetetramine to form the resite structure of PFR. The influence of PFR modifiers (nickel sulfate, ETS­40) on the formation of the PFR resite structure and the SiO2 framework structure was identified, and their combined introduction was recommended to enhance the cold crushing strength to 56.3 MPa in magnesia­carbon materials after heat treatment at 180—200 ºС. It was shown that to ensure high­strength characteristics, the amount of nickel sulfate introduced into the PFR should not exceed 0.1 wt. %.