Formation of liquid‐phase isolation layer on the corroded interface of MgO/Al₂O₃‐SiC‐C refractory and molten steel: Role of SiC

Abstract

Formation of a dense layer on corroded interface to suppress corrosion is always desired, but it is controlled by numerous environmental conditions. In this work, corroded microstructures of MgO/Al2O3‐SiC‐C refractories in metal bath area of ladle furnace were investigated after industrial trails. A liquid‐phase isolation layer in which MgO islands and liquid phases was established on the corroded interface of refractories with 6 wt% coarse/fine SiC‐additive. The formed isolation layer against steel/slag attacks led to an approximate 30% improvement in corrosion resistance than that of refractory with 3 wt% fine SiC‐additive. More importantly, the liquid‐phase isolation layer blocked the direct mass transfer between molten steel and refractories while it decreased exogenous pollution from refractories. SiC‐additive affected the formation process of isolation layer by controlling the generation/migration of Mg(g) on refractory' surface. A further formation mechanism of liquid‐phase isolation layer was discussed in detail and role of SiC was elucidated.

Synthesis of Al2O3‐SiC powder from electroceramics waste and its application in low‐carbon MgO‐C refractories

“…However, because the formation conditions of the MgO dense layer are very harsh and are affected by many factors, the accuracy of the theory remains to be verified 31 . In addition, studies have shown that the introduction of some additives can effectively prevent the penetration of the slag into the refractories by forming a high‐viscosity liquid phase isolation layer at the slag‐refractory interface 32 . This theory is consistent with the corrosion test results of this work.…”

“…31 In addition, studies have shown that the introduction of some additives can effectively prevent the penetration of the slag into the refractories by forming a high-viscosity liquid phase isolation layer at the slag-refractory interface. 32 This theory is consistent with the corrosion test results of this work. First of all, samples M0 and M7.5 present greater corroded depth due to high apparent porosity (9.05% and 8.92%, respectively); secondly, samples M2.5, M5, and M7.5 all show a small penetrated depth due to the formation of a high-viscosity isolation layer (the role of Si provided by composite powder); thirdly, the in situ spinel formed between Al 2 O 3 in the composite powder and MgO also contributes to the improvement of the slag resistance of the MgO-C samples.…”

One-Pot Synthesis of Alumina-Titanium Diboride Composite Powder at Low Temperature

“…To assist in clarification of the mechanisms underpinning the whole reaction/synthesis process, thermodynamic calculations were carried out using the commercial FactSage package [40]. The Gibbs energy values for each of the intermediate reactions and the overall reaction (Reaction (1)), as a function of temperature, were calculated.…”

Formation of ferrospinel layer at the corroded interface between Al2O3‐spinel refractory and molten steel in RH refining ladle

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Incorporation of magnesia alumina spinel confers excellent thermal shock/spalling resistance, good slag resistance, high creep resistance and refractoriness, on calcium aluminate cement bonded corundum-magnesia alumina spinel (Al 2 O 3 -MgAl 2 O 4 ) refractory castables. [1][2][3][4] To date, they have been widely applied as lining materials in refining ladles, 1,5,6 Ruhrstahl Heraeus (RH) snorkels, 7-9 purging plug, 10 and slagging gasifiers, 11-12 etc.Their corrosion behaviors in the clean steel refining processes mentioned above have been extensively investigated. [13][14][15][16][17] Zhang and Lee studied the dissolution processes of fused and tabular corundum aggregates in a silicate slag, and observed the formation of calcium hexaaluminate (CA 6 ) and hercynitic spinel layers close to the Al 2 O 3 /slag interfaces, whose continuity and morphology varied, dominating the indirect or direct dissolution processes.

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“…Incorporation of magnesia alumina spinel confers excellent thermal shock/spalling resistance, good slag resistance, high creep resistance and refractoriness, on calcium aluminate cement bonded corundum-magnesia alumina spinel (Al 2 O 3 -MgAl 2 O 4 ) refractory castables. [1][2][3][4] To date, they have been widely applied as lining materials in refining ladles, 1,5,6 Ruhrstahl Heraeus (RH) snorkels, 7-9 purging plug, 10 and slagging gasifiers, 11-12 etc.…”