Insights into the mechanisms controlling the residual corrosion rate of borosilicate glasses

Abstract Borosilicate glasses are widely used to confine high-level radioactive wastes. The lifetime of these materials could reach hundreds of thousands of years if leaching of the glass into groundwater enables the formation of a passivating gel layer. Even in this regime, the glass will never sto...

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Autores principales:	Stephane Gin, Xiaolei Guo, Jean-Marc Delaye, Frédéric Angeli, Kamalesh Damodaran, Véronique Testud, Jincheng Du, Sebastien Kerisit, Seong H. Kim
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2020
Materias:	Materials of engineering and construction. Mechanics of materials TA401-492
Acceso en línea:	https://doaj.org/article/2c74a8c5d2174093a0ca079439cd0e08
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spelling	oai:doaj.org-article:2c74a8c5d2174093a0ca079439cd0e082021-12-02T16:10:53ZInsights into the mechanisms controlling the residual corrosion rate of borosilicate glasses10.1038/s41529-020-00145-22397-2106https://doaj.org/article/2c74a8c5d2174093a0ca079439cd0e082020-12-01T00:00:00Zhttps://doi.org/10.1038/s41529-020-00145-2https://doaj.org/toc/2397-2106Abstract Borosilicate glasses are widely used to confine high-level radioactive wastes. The lifetime of these materials could reach hundreds of thousands of years if leaching of the glass into groundwater enables the formation of a passivating gel layer. Even in this regime, the glass will never stop corroding as thermodynamic equilibrium between glass and solution cannot be achieved. Therefore, accurate predictions of glass durability including passivation, require a deep understanding of the mechanisms controlling the so-called residual rate. However, despite tremendous efforts, these mechanisms remain poorly understood. Here, focusing on the behavior of the soluble elements of the International Simple Glass (B, Na, and Ca), we show that the residual rate is controlled by the behavior of B, a glass former supposed to dissolve instantaneously when in contact with water and thus widely considered as an ideal tracer. We then demonstrate that B release is controlled by multiple processes highly dependent on the pH. At the beginning of the passivating layer formation, the hydrolysis of B-O-Si linkages is rate-limiting and has an activation energy of ∼60 kJ mol−1, a value slightly lower than that for breaking Si-O-Si linkages. Once the fraction of closed pores resulting from gel restructuring is high enough, then diffusion of both reactants (water molecules) and some products (mainly Baq, Caaq) through the growing gel layer becomes rate-limiting. Consequently, B and Ca accumulate in an inner layer referred to as the active zone, with potential feedback on the B-O-Si hydrolysis. A new paradigm, including B as a key element of the system, is proposed to develop a comprehensive model for the corrosion of borosilicate glass.Stephane GinXiaolei GuoJean-Marc DelayeFrédéric AngeliKamalesh DamodaranVéronique TestudJincheng DuSebastien KerisitSeong H. KimNature PortfolioarticleMaterials of engineering and construction. Mechanics of materialsTA401-492ENnpj Materials Degradation, Vol 4, Iss 1, Pp 1-9 (2020)
institution	DOAJ
collection	DOAJ
language	EN
topic	Materials of engineering and construction. Mechanics of materials TA401-492
spellingShingle	Materials of engineering and construction. Mechanics of materials TA401-492 Stephane Gin Xiaolei Guo Jean-Marc Delaye Frédéric Angeli Kamalesh Damodaran Véronique Testud Jincheng Du Sebastien Kerisit Seong H. Kim Insights into the mechanisms controlling the residual corrosion rate of borosilicate glasses
description	Abstract Borosilicate glasses are widely used to confine high-level radioactive wastes. The lifetime of these materials could reach hundreds of thousands of years if leaching of the glass into groundwater enables the formation of a passivating gel layer. Even in this regime, the glass will never stop corroding as thermodynamic equilibrium between glass and solution cannot be achieved. Therefore, accurate predictions of glass durability including passivation, require a deep understanding of the mechanisms controlling the so-called residual rate. However, despite tremendous efforts, these mechanisms remain poorly understood. Here, focusing on the behavior of the soluble elements of the International Simple Glass (B, Na, and Ca), we show that the residual rate is controlled by the behavior of B, a glass former supposed to dissolve instantaneously when in contact with water and thus widely considered as an ideal tracer. We then demonstrate that B release is controlled by multiple processes highly dependent on the pH. At the beginning of the passivating layer formation, the hydrolysis of B-O-Si linkages is rate-limiting and has an activation energy of ∼60 kJ mol−1, a value slightly lower than that for breaking Si-O-Si linkages. Once the fraction of closed pores resulting from gel restructuring is high enough, then diffusion of both reactants (water molecules) and some products (mainly Baq, Caaq) through the growing gel layer becomes rate-limiting. Consequently, B and Ca accumulate in an inner layer referred to as the active zone, with potential feedback on the B-O-Si hydrolysis. A new paradigm, including B as a key element of the system, is proposed to develop a comprehensive model for the corrosion of borosilicate glass.
format	article
author	Stephane Gin Xiaolei Guo Jean-Marc Delaye Frédéric Angeli Kamalesh Damodaran Véronique Testud Jincheng Du Sebastien Kerisit Seong H. Kim
author_facet	Stephane Gin Xiaolei Guo Jean-Marc Delaye Frédéric Angeli Kamalesh Damodaran Véronique Testud Jincheng Du Sebastien Kerisit Seong H. Kim
author_sort	Stephane Gin
title	Insights into the mechanisms controlling the residual corrosion rate of borosilicate glasses
title_short	Insights into the mechanisms controlling the residual corrosion rate of borosilicate glasses
title_full	Insights into the mechanisms controlling the residual corrosion rate of borosilicate glasses
title_fullStr	Insights into the mechanisms controlling the residual corrosion rate of borosilicate glasses
title_full_unstemmed	Insights into the mechanisms controlling the residual corrosion rate of borosilicate glasses
title_sort	insights into the mechanisms controlling the residual corrosion rate of borosilicate glasses
publisher	Nature Portfolio
publishDate	2020
url	https://doaj.org/article/2c74a8c5d2174093a0ca079439cd0e08
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Insights into the mechanisms controlling the residual corrosion rate of borosilicate glasses

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