关键词: 浸入式水口, Ti(C,N)复合粉体, Si粉, 力学性能, 抗氧化性能

Abstract: To develop Si-free antioxidants for the body of submerged entry nozzles (SENs),alumina-carbon (Al₂O₃-C) refractories were prepared using tabular corundum,flake graphite,α-Al₂O₃ powder,Ti(C,N) composite powder and silicon powder as raw materials,phenolic resin as the binder,and industrial alcohol as the solvent.The prepared samples were cured at 200 ℃ for 24 h,followed by heat treatment at 1 000 ℃ for 3 h under an argon atmosphere.The effects of the Ti(C,N) composite powder or Si powder addition (mass fractions of 0,0.5%,0.75%,1.0%,1.25% and 1.5%) on the mechanical properties,thermal shock resistance and oxidation resistance of the materials were investigated.The results show that with the increasing addition of Ti(C,N) composite powder or Si powder,the apparent porosity,bulk density and cold modulus of rupture of the heat-treated samples have no obvious change.Nevertheless,Ti(C,N) composite powder can significantly improve the cold crushing strength,with the maximum achieved at a Ti(C,N) addition of 0.75%.The hot modulus of rupture of the samples first increases and then decreases with the rising addition of either Si powder or Ti(C,N) composite powder.The MOR retention ratio of the samples increases gradually with the increasing Si addition,while a decreasing trend is observed with the increasing Ti(C,N) addition.The sample with 0.75% Ti(C,N) composite powder exhibits the optimal oxidation resistance.This is mainly because TiN and TiC possess lower Gibbs free energy of oxidation reaction,and their oxidation products TiO₂ and Al₂TiO₅ have superior volume expansion effects,which can pre-ferentially form a dense protective layer to block internal pores.In summary,the sample with 0.75% Ti(C,N) composite powder delivers excellent comprehensive performance,showing promising application potential to replace silicon-containing antioxidants.

Key words: submerged entry nozzles, Ti(C,N) composite powder, Si powder, mechanical properties, oxidation resistance