Slag corrosion characteristics of MgO-based refractories under vacuum electromagnetic field

Self Cite

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.

Section: Resultsmentioning

confidence: 99%

Section: Effects Of As-synthesized Al 2 O 3 -Sic Powder On the Oxidat...mentioning

confidence: 99%

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

Ren

Zhi

et al. 2021

Self Cite

“…Magnesia-based refractories are widely used as lining of steel ladles and cement rotary kilns due to their superior slag corrosion resistance and high-temperature mechanical properties. [1][2][3][4][5][6][7] Conventional magnesia-based refractories prepared by sintered or fused dense aggregates as raw materials, have high thermal conductivity and bulk density, leading to excessive heat loss through refractory lining. To mitigate the heat loss, microporous aggregates were used to prepare the lightweight refractories for working linings, instead of dense aggregates.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of fracture behavior of lightweight magnesia‐based refractories via wedge splitting test along with acoustic emission detection

Yan

Dai

et al. 2023

The effect of spinel powder on the fracture behavior and mechanical properties of lightweight magnesia‐based refractories containing microporous magnesia aggregates with high apparent porosity (37.4%) were investigated by the wedge splitting test (WST) with the digital image correlation and acoustic emission. With the addition of spinel powder, lightweight magnesia spinel refractories showed a higher cold compressive strength compared with lightweight pure magnesia refractories. From the WST, the addition of spinel powder increased the specific fracture energy and characteristic length of lightweight magnesia spinel refractories, which improved the crack propagation resistance. The increased tortuosity of main crack and a higher ratio of crack propagation along the aggregates/matrix interface were main reasons for reducing the brittleness of lightweight magnesia spinel refractories. Besides, acoustic emission (AE) signal activity indicated that the propagation of pregenerated micro‐cracks by the thermal mismatch and the development of fracture progress zone were primary ways to consume energy in lightweight magnesia spinel refractories. The reduced proportion of crack propagation within aggregates was also detected by the peak frequency of AE signals in lightweight magnesia spinel refractories. For microporous magnesia aggregates with high apparent porosity (37.4%), lightweight magnesia spinel refractories also showed reduced brittleness fracture behavior than lightweight pure magnesia refractories.

“…MgO–Al 2 O 3 refractories are widely used in steel making and cement production due to their excellent corrosion resistance and high‐temperature mechanical properties 1–9 . In recent years, efficient thermal insulation refractories have been constantly studied for energy conservation and carbon emission reduction 10–14 .…”

Section: Introductionmentioning

confidence: 99%

Microstructure and properties of microporous MgO–Al₂O₃ refractory aggregates from Mg(OH)₂ and Al(OH)₃

Yan,

Wang

et al. 2023

In this work, microporous MgO–Al2O3 refractory aggregates were prepared with Mg(OH)2 and Al(OH)3 via the in situ decomposition synthesis method. The effect of Al(OH)3 addition on the microstructure and properties of microporous MgO–Al2O3 refractory aggregates was investigated with scanning electron microscope and mercury intrusion porosimetry. The results indicated that the improved green density of the samples and the reaction sintering accelerated the mass transport rate with adding Al(OH)3 from 0 to 4.0 wt%. Besides, a small amount of Al3+ diffused into porous MgO particles, accelerating the merging and growth of nanopores in the porous MgO particles. The intra‐particle pore size and the densification degree of microparticles were increased, and thus the strength of the samples was improved. Due to the formation of Kirkendall voids by interdiffusion of Mg2+ and Al3+, the inter‐particle pore size increased. Adding Al(OH)3 from 4.0 to 17.6 wt%, the Kirkendall voids weakened the mass transport rate and improved the inter‐particle pore size. The merging and growth of nanopores in the MgO particles were limited, resulting in the reduced intra‐particle pore size and increased intra‐particle pore number. The densification degree of microparticles was reduced, and thus the strength of the samples decreased. At the Al(OH)3 addition of 4.0 wt%, microporous MgO–Al2O3 refractory aggregates had the best comprehensive properties, a bulk density of 2.48 g/cm3, an apparent porosity of 29.4%, a median pore size of 1.6 μm with 42.2 vol% nanopores and the thermal conductivity of 4.0 W/(m K).