Oxidation-resistant nano-reinforced PC-refractories of modified phenol formaldehyde resin. Part 3. Formation mechanism of organic-inorganic complexes during low-temperature synthesis of nanoparticles of additional antioxidants and their effectiveness

SiC nanoparticles that could be used as an antioxidant for periclase-carbon (PC) refractories were synthesized from the organic—inorganic complex (‒СН₃)‒(SiO₂)n that formed during heating of silicon alkoxide and thermal destruction of its gels. Use of phenolformaldehyde resins modified with silicon alkoxide and its sols was proposed and enabled the formation of an organic—inorganic complex (-СН₃)‒(SiO₂)n‒С with a high C content. This increased the yield of SiC synthesized in the carbon binder. The addition of Ni precursors (additional antioxidant) formed an even more complicated organic—inorganic complex. Use of the complex (‒СН₃)‒(SiO₂)n‒Ni(NiO)‒С together with Al improved the operating characteristics of the PC refractories. It was found that their resistance to oxidation was increased after the complex antioxidant Al + SiC + Ni(NiO) formed

Oxidation resistance of nano-reinforced PC-refractories modified with phenol formaldehyde resin. Part 4. Thermodynamic evaluation of phase formation within Mg–O–C–Al, Mg–O–C–Ni and МgO‒Al₂O₃‒NiO‒SiO₂ systems using SiC + Al + Ni (NiO) complex antioxidant

Results are given for the synthesis and co-existence of phases formed from components of complex organic- inorganic antioxidant formed during modification of phenol-formaldehyde resin (PFR) and graphite with silica alkoxide and inorganic or organic nickel precursors. Thermodynamic analysis is given for the Mg–Al–C and Mg–O–Ni–C systems. It is shown that the periclase and carbon can coexist with aluminum and nickel, and also that oxidized antioxidants Al₂O₃ and NiO can interact respectively with the periclase and with the synthesized SiC formed during modification of PFR with silica. In considering the NiO‒MgO‒Al₂O₃‒SiO₂ system it is established that during service noble spinel will be synthesized from the complex antioxidant components, facilitating an increase in PC-refractory durability in service