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

Abstract

Composite additives are an efficient means to improve the high‐temperature stability and slag resistance of low‐carbon MgO‐C refractories. In this work, Al2O3‐SiC powder was firstly synthesized from electroceramics waste by carbon embedded method at 1500°C, 1550°C, and 1600°C for 4 h, and then the as‐synthesized Al2O3‐SiC powder was used as an additive to low‐carbon MgO‐C refractories. The effects of its addition amounts of 0, 2.5 wt.%, 5.0 wt.%, and 7.5 wt.% on the properties of the refractories were investigated in detail. It was found that increasing the heat treatment temperature is beneficial to the phase conversion of mullite and quartz to alumina and silicon carbide in the electroceramics waste. Furthermore, the addition of Al2O3‐SiC powder effectively improves the performance of low‐carbon MgO‐C samples, and the formation of spinel dense layer and high‐viscosity isolation layer is the internal reason for the improvement of the oxidation resistance and slag resistance of low‐carbon MgO‐C samples. This work provides ideas for the reuse of electroceramics waste and presents an alternative strategy for the performance optimization of low‐carbon MgO‐C refractories.

Effects of Al 2 O 3 –Y 2 O 3 /Yb 2 O 3 additives on microstructures and mechanical properties of silicon nitride ceramics prepared by hot‐pressing sintering

“…The scan speed was 10°/min, and 2 θ varied from 10° to 80°. The specimen surface was etched by a plasma etching apparatus (RF Plasma Barrel Etcher PT 7150) 27 . The etchant gas was CF 4 gas adjusted to a total pressure of .3 mbar.…”

“…The specimen surface was etched by a plasma etching apparatus (RF Plasma Barrel Etcher PT 7150). 27 The etchant gas was CF 4 gas adjusted to a total pressure of .3 mbar. Etching was conducted at 100 W for up to 4 min.…”

Microstructures and strengths of microporous MgO–Al2O3 ceramics from Al(OH)3 and calcined magnesite

“…Currently, lightweight refractories for working lining have been widely studied. [20][21][22][23][24][25] Generally, microporous aggregates can be obtained by crushing and screening porous ceramics. [26][27][28][29][30][31][32] At present, porous MgO-Al 2 O 3 ceramics can be produced not only by the template method, 33 but also by direct foam gelcasting, 34 in situ decomposition synthesis.…”

“…In recent years, the design of lightweight and low conductivity working linings with refractories containing microporous aggregates 15–19 was proposed to reduce their thermal conductivity. Currently, lightweight refractories for working lining have been widely studied 20–25 …”

In situ synthesis and interfacial bonding mechanism of SiC in MgO–SiC–C refractories

“…The addition of SiC improves the strength, 19 toughness, 20 slag corrosion resistance, 21 and thermal shock resistance 22 of multiphase materials. Ma et al [23][24][25] found that the addition of the synthesized Al 2 O 3 -SiC could improve the slag permeability and slag resistance of low-carbon MgO-C refractories due to the formation of spinel dense layer and high-viscosity isolation layer. Therefore, the addition of SiC to MgO-C refractories has essential research significance.…”