High-Temperature Chemical Stability of Cr(III) Oxide Refractories in the Presence of Calcium Aluminate Cement

High-Temperature Chemical Stability of Cr(III) Oxide Refractories in the Presence of Calcium Aluminate Cement

Al<sub>2</sub>O<sub>3</sub>-CaO-Cr<sub>2</sub>O<sub>3</sub> castables are used in various furnaces due to excellent corrosion resistance and sufficient early strength, but toxic Cr(VI) generation during service remains a concern. Here, we investigated...

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Autores principales: Tengteng Xu, Yibiao Xu, Ning Liao, Yawei Li, Mithun Nath
Formato: article
Lenguaje:EN
Publicado: MDPI AG 2021
Materias:
Al<sub>2</sub>O<sub>3</sub>-CaO-Cr<sub>2</sub>O<sub>3</sub>-O<sub>2</sub> system
(Al<sub>1−x</sub>Cr<sub>x</sub>)<sub>2</sub>O<sub>3</sub>
Ca(Al<sub>12−x</sub>Cr<sub>x</sub>)O<sub>19</sub>
Cr(VI) compounds
leaching test
Technology
T
Electrical engineering. Electronics. Nuclear engineering
TK1-9971
Engineering (General). Civil engineering (General)
TA1-2040
Microscopy
QH201-278.5
Descriptive and experimental mechanics
QC120-168.85
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spelling oai:doaj.org-article:b072899da87c4a728dc3a0273c77190a2021-11-11T18:07:55ZHigh-Temperature Chemical Stability of Cr(III) Oxide Refractories in the Presence of Calcium Aluminate Cement10.3390/ma142165901996-1944https://doaj.org/article/b072899da87c4a728dc3a0273c77190a2021-11-01T00:00:00Zhttps://www.mdpi.com/1996-1944/14/21/6590https://doaj.org/toc/1996-1944Al<sub>2</sub>O<sub>3</sub>-CaO-Cr<sub>2</sub>O<sub>3</sub> castables are used in various furnaces due to excellent corrosion resistance and sufficient early strength, but toxic Cr(VI) generation during service remains a concern. Here, we investigated the relative reactivity of analogous Cr(III) phases such as Cr<sub>2</sub>O<sub>3</sub>, (Al<sub>1−x</sub>Cr<sub>x</sub>)<sub>2</sub>O<sub>3</sub> and in situ Cr(III) solid solution with the calcium aluminate cement under an oxidizing atmosphere at various temperatures. The aim is to comprehend the relative Cr(VI) generation in the low-cement castables (Al<sub>2</sub>O<sub>3</sub>-CaO-Cr<sub>2</sub>O<sub>3</sub>-O<sub>2</sub> system) and achieve an environment-friendly application. The solid-state reactions and Cr(VI) formation were investigated using powder XRD, SEM, and leaching tests. Compared to Cr<sub>2</sub>O<sub>3</sub>, the stability of (Al<sub>1−x</sub>Cr<sub>x</sub>)<sub>2</sub>O<sub>3</sub> against CAC was much higher, which improved gradually with the concentration of Al<sub>2</sub>O<sub>3</sub> in (Al<sub>1−x</sub>Cr<sub>x</sub>)<sub>2</sub>O<sub>3</sub>. The substitution of Cr<sub>2</sub>O<sub>3</sub> with (Al<sub>1−x</sub>Cr<sub>x</sub>)<sub>2</sub>O<sub>3</sub> in the Al<sub>2</sub>O<sub>3</sub>-CaO-Cr<sub>2</sub>O<sub>3</sub> castables could completely inhibit the formation of Cr(VI) compound CaCrO<sub>4</sub> at 500–1100 °C and could drastically suppress Ca<sub>4</sub>Al<sub>6</sub>CrO<sub>16</sub> generation at 900 to 1300 °C. The Cr(VI) reduction amounting up to 98.1% could be achieved by replacing Cr<sub>2</sub>O<sub>3</sub> with (Al<sub>1−x</sub>Cr<sub>x</sub>)<sub>2</sub>O<sub>3</sub> solid solution. However, in situ stabilized Cr(III) phases as a mixture of (Al<sub>1−x</sub>Cr<sub>x</sub>)<sub>2</sub>O<sub>3</sub> and Ca(Al<sub>12−x</sub>Cr<sub>x</sub>)O<sub>19</sub> solid solution hardly reveal any reoxidation. Moreover, the CA<sub>6</sub> was much more stable than CA and CA<sub>2</sub>, and it did not participate in any chemical reaction with (Al<sub>1−x</sub>Cr<sub>x</sub>)<sub>2</sub>O<sub>3</sub> solid solution.Tengteng XuYibiao XuNing LiaoYawei LiMithun NathMDPI AGarticleAl<sub>2</sub>O<sub>3</sub>-CaO-Cr<sub>2</sub>O<sub>3</sub>-O<sub>2</sub> system(Al<sub>1−x</sub>Cr<sub>x</sub>)<sub>2</sub>O<sub>3</sub>Ca(Al<sub>12−x</sub>Cr<sub>x</sub>)O<sub>19</sub>Cr(VI) compoundsleaching testTechnologyTElectrical engineering. Electronics. Nuclear engineeringTK1-9971Engineering (General). Civil engineering (General)TA1-2040MicroscopyQH201-278.5Descriptive and experimental mechanicsQC120-168.85ENMaterials, Vol 14, Iss 6590, p 6590 (2021)
institution DOAJ
collection DOAJ
language EN
topic Al<sub>2</sub>O<sub>3</sub>-CaO-Cr<sub>2</sub>O<sub>3</sub>-O<sub>2</sub> system
(Al<sub>1−x</sub>Cr<sub>x</sub>)<sub>2</sub>O<sub>3</sub>
Ca(Al<sub>12−x</sub>Cr<sub>x</sub>)O<sub>19</sub>
Cr(VI) compounds
leaching test
Technology
T
Electrical engineering. Electronics. Nuclear engineering
TK1-9971
Engineering (General). Civil engineering (General)
TA1-2040
Microscopy
QH201-278.5
Descriptive and experimental mechanics
QC120-168.85
spellingShingle Al<sub>2</sub>O<sub>3</sub>-CaO-Cr<sub>2</sub>O<sub>3</sub>-O<sub>2</sub> system
(Al<sub>1−x</sub>Cr<sub>x</sub>)<sub>2</sub>O<sub>3</sub>
Ca(Al<sub>12−x</sub>Cr<sub>x</sub>)O<sub>19</sub>
Cr(VI) compounds
leaching test
Technology
T
Electrical engineering. Electronics. Nuclear engineering
TK1-9971
Engineering (General). Civil engineering (General)
TA1-2040
Microscopy
QH201-278.5
Descriptive and experimental mechanics
QC120-168.85
Tengteng Xu
Yibiao Xu
Ning Liao
Yawei Li
Mithun Nath
High-Temperature Chemical Stability of Cr(III) Oxide Refractories in the Presence of Calcium Aluminate Cement
description Al<sub>2</sub>O<sub>3</sub>-CaO-Cr<sub>2</sub>O<sub>3</sub> castables are used in various furnaces due to excellent corrosion resistance and sufficient early strength, but toxic Cr(VI) generation during service remains a concern. Here, we investigated the relative reactivity of analogous Cr(III) phases such as Cr<sub>2</sub>O<sub>3</sub>, (Al<sub>1−x</sub>Cr<sub>x</sub>)<sub>2</sub>O<sub>3</sub> and in situ Cr(III) solid solution with the calcium aluminate cement under an oxidizing atmosphere at various temperatures. The aim is to comprehend the relative Cr(VI) generation in the low-cement castables (Al<sub>2</sub>O<sub>3</sub>-CaO-Cr<sub>2</sub>O<sub>3</sub>-O<sub>2</sub> system) and achieve an environment-friendly application. The solid-state reactions and Cr(VI) formation were investigated using powder XRD, SEM, and leaching tests. Compared to Cr<sub>2</sub>O<sub>3</sub>, the stability of (Al<sub>1−x</sub>Cr<sub>x</sub>)<sub>2</sub>O<sub>3</sub> against CAC was much higher, which improved gradually with the concentration of Al<sub>2</sub>O<sub>3</sub> in (Al<sub>1−x</sub>Cr<sub>x</sub>)<sub>2</sub>O<sub>3</sub>. The substitution of Cr<sub>2</sub>O<sub>3</sub> with (Al<sub>1−x</sub>Cr<sub>x</sub>)<sub>2</sub>O<sub>3</sub> in the Al<sub>2</sub>O<sub>3</sub>-CaO-Cr<sub>2</sub>O<sub>3</sub> castables could completely inhibit the formation of Cr(VI) compound CaCrO<sub>4</sub> at 500–1100 °C and could drastically suppress Ca<sub>4</sub>Al<sub>6</sub>CrO<sub>16</sub> generation at 900 to 1300 °C. The Cr(VI) reduction amounting up to 98.1% could be achieved by replacing Cr<sub>2</sub>O<sub>3</sub> with (Al<sub>1−x</sub>Cr<sub>x</sub>)<sub>2</sub>O<sub>3</sub> solid solution. However, in situ stabilized Cr(III) phases as a mixture of (Al<sub>1−x</sub>Cr<sub>x</sub>)<sub>2</sub>O<sub>3</sub> and Ca(Al<sub>12−x</sub>Cr<sub>x</sub>)O<sub>19</sub> solid solution hardly reveal any reoxidation. Moreover, the CA<sub>6</sub> was much more stable than CA and CA<sub>2</sub>, and it did not participate in any chemical reaction with (Al<sub>1−x</sub>Cr<sub>x</sub>)<sub>2</sub>O<sub>3</sub> solid solution.
format article
author Tengteng Xu
Yibiao Xu
Ning Liao
Yawei Li
Mithun Nath
author_facet Tengteng Xu
Yibiao Xu
Ning Liao
Yawei Li
Mithun Nath
author_sort Tengteng Xu
title High-Temperature Chemical Stability of Cr(III) Oxide Refractories in the Presence of Calcium Aluminate Cement
title_short High-Temperature Chemical Stability of Cr(III) Oxide Refractories in the Presence of Calcium Aluminate Cement
title_full High-Temperature Chemical Stability of Cr(III) Oxide Refractories in the Presence of Calcium Aluminate Cement
title_fullStr High-Temperature Chemical Stability of Cr(III) Oxide Refractories in the Presence of Calcium Aluminate Cement
title_full_unstemmed High-Temperature Chemical Stability of Cr(III) Oxide Refractories in the Presence of Calcium Aluminate Cement
title_sort high-temperature chemical stability of cr(iii) oxide refractories in the presence of calcium aluminate cement
publisher MDPI AG
publishDate 2021
url https://doaj.org/article/b072899da87c4a728dc3a0273c77190a
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AT yaweili hightemperaturechemicalstabilityofcriiioxiderefractoriesinthepresenceofcalciumaluminatecement
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