Analysis of the Formed Protective Layer Inhibiting Alkali Corrosion in Aluminosilicate Refractory Castables

Antonovič, Valentin; Stonys, Rimvydas; Zdanevičius, Povilas; Mačiulaitis, Romualdas; Boris, Renata; Malaiškienė, Jurgita

doi:10.3390/ceramics5040075

Cited by 3 publications

(1 citation statement)

References 34 publications

(47 reference statements)

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“…Additionally, the same fireclay after 1 h of milling and sieving through a sieve with a mesh size of 0.14 mm was used as fine aggregate. Milled quartz sand (MQS) was used to improve the fireclay refractories resistance to alkali attack [29]. The following deflocculants were used: Castament FS20 and FS30 from BASF Construction Solutions GmbH (Trostberg, Germany) and technical sodium tripolyphosphate NT.…”

Section: Methodsmentioning

confidence: 99%

Analysis of the Structure and Durability of Refractory Castables Impregnated with Sodium Silicate Glass

Malaiškienė,

Antonovič,

Boris

et al. 2023

Ceramics

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This study examines the impact of the impregnation of fireclay-based conventional (CC) and medium-cement castables (MCCs) with liquid sodium silicate glass under vacuum conditions. The goal is to assess how this treatment affects the physical and mechanical properties and durability (alkali and thermal shock resistance) of these castables used in biomass combustion boilers, where they are exposed to temperatures up to 1100 °C. The research work employs standard test methods to evaluate the physical and mechanical properties. Additionally, advanced techniques such as scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and specific tests for alkali resistance and thermal shock resistance are used. The research findings suggest that impregnation with sodium silicate glass under vacuum significantly enhances the alkali resistance of both CC and MCCs. This improvement is primarily due to the reduction in porosity and the increase in density. SEM images reveal that the impregnated samples are coated with a glassy layer and the pores are partially filled with sodium silicate. Tests for alkali resistance demonstrate the formation of a protective glassy layer (with a thickness of 0.9–1.5 mm) on the castable surfaces, thereby reducing the further penetration of alkali into deeper layers of the samples. However, it is important to mention that the impregnated refractory castables have reduced resistance to thermal shock cycles.

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Section: Methodsmentioning

confidence: 99%

Analysis of the Structure and Durability of Refractory Castables Impregnated with Sodium Silicate Glass

Malaiškienė,

Antonovič,

Boris

et al. 2023

Ceramics

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Analysis of the Structure and Durability of Refractory Castables Impregnated with Sodium Silicate Glass

Malaiškienė,

Antonovič,

Boris

et al. 2023

Preprint

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This study examines the impact of the impregnation of fireclay-based conventional (CC) and medium cement castables (MCC) with liquid sodium silicate glass under vacuum conditions. The goal is to assess how this treatment affects physical, mechanical properties, and durability (alkali and thermal shock resistance) of these castables used in biomass combustion boilers, where they are exposed to temperatures up to 1100°C. The research work employs standard test methods to evaluate physical and mechanical properties. Additionally, advanced techniques such as scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and specific tests for alkali resistance and thermal shock resistance are used. The research findings suggest that impregnation with sodium silicate glass under vacuum significantly enhances the alkali resistance of both CC and MCC castables. This improvement is primarily due to the reduction in porosity and the increase in density. SEM images reveal that impregnated samples are coated with a glassy layer and the pores are partially filled with sodium silicate. Tests for alkali resistance demonstrate the formation of a protective glassy layer (with a thickness of 0.9-1.5 mm) on the castables surfaces, thereby reducing further penetration of alkali into deeper layers of the samples. However, it is important to mention that impregnated refractory castables have reduced resistance to thermal shock cycles.

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Possibilities to Recycle Thermal Power Plant By-Products in Refractory Castables

Škamat,

Boris,

Malaiškienė

et al. 2024

Sustainability

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The current research focuses on the analysis of fly ash cenospheres (FACs), a waste generated in coal-fired power plants, and the possibilities of using them in refractory castables. Cenospheres are micro-scale (~50–400 µm) spherical structures derived from fly ash, predominantly composed of silica and alumina oxides (86.7%). Their distinctive morphology and characteristics make them highly advantageous for a diverse array of applications, notably as lightweight fillers and nondegradable pore-forming agents. Furthermore, cenospheres have the potential to contribute significantly to the performance of refractory castables when incorporated into compositions with calcium aluminate cement (CAC). FAC XRD analysis revealed that FACs mainly consist of mullite along with cristobalite, which forms at higher temperatures. Furthermore, the study examined the impact of FACs on the properties of medium cement castable (MCC), especially durability, when 3%, 5%, and 7% of fine fireclay were replaced by FACs; 5% of FACs were found to reduce the density of refractory castables and decrease the cold crushing strength by approximately 6%, but it increased the resistance to thermal shock by approximately 75% and 43%, depending on the thermal treatment temperature, 950 °C and 1100 °C, respectively, and improved resistance to alkali corrosion. A higher FAC content (7%) does not have any positive effect on the MCC properties tested.

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Analysis of the Formed Protective Layer Inhibiting Alkali Corrosion in Aluminosilicate Refractory Castables

Cited by 3 publications

References 34 publications

Analysis of the Structure and Durability of Refractory Castables Impregnated with Sodium Silicate Glass

Analysis of the Structure and Durability of Refractory Castables Impregnated with Sodium Silicate Glass

Analysis of the Structure and Durability of Refractory Castables Impregnated with Sodium Silicate Glass

Possibilities to Recycle Thermal Power Plant By-Products in Refractory Castables

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