Glass corrosion mechanism

Noguf.s, J.-L., Vernaz, E. Y. Jacquet-Francillon, N. 1985. Nuclear glass corrosion mechanisms applied to the French LWR reference glass. In Jantzen, C. M., Stone, J. A. Ewing, R. C. (eds) Scientific Basis for Nuclear Waste Management VIII. Materials Research Society Symposia Proceedings, 44, 89-98. 

Vernaz, E. Dussosoy, J.-L. 1992. Current state knowledge of nuclear waste glass corrosion mechanisms The case of R7T7 glass. Applied Geochemistry (Supplement Issue), 1, 13-22. 

C. CaiUeteau et al.. Insight into silicate-glass corrosion mechanisms. Nat. Mater 7(12), 978-... 

Scholze, H., Conradt, R., Engelke, H. Roggendorf, H. 1982. Determination of the corrosion mechanisms of high-level waste containing glass. In Lutze, W. (ed) Scientific Basis for Nuclear Waste Management V. Materials Research Society Symposia Proceedings, 11, 173-180. 

There are a number of mechanisms that pose potential problems to predicting dissolution rate kinetics as the system approaches saturation. Part of this conundrum originates from current models of glass corrosion kinetics that cannot yet incorporate these unanticipated phenomena into a mathematical equation that is consistent with the constraints of thermodynamics or kinetics. These phenomena include (1) alkali-hydrogen exchange (2) dissimilar reactivity of... 

Figure 10. Mechanisms of glass corrosion for a soda-silica glass. Conditions a, t = 0, pH = 7 b (stage 1), t > 0, pH < 9, selective Na dissolution and c (stage 2), t 0, pH 9 total dissolution. (Reproduced, with permission, from Ref. 1. Copyright 1979, Books for Industry.)...

In the past ten years the number of chemistry-related research problems in the nuclear industry has increased dramatically. Many of these are related to surface or interfacial chemistry. Some applications are reviewed in the areas of waste management, activity transport in coolants, fuel fabrication, component development, reactor safety studies, and fuel reprocessing. Three recent studies in surface analysis are discussed in further detail in this paper. The first concerns the initial corrosion mechanisms of borosilicate glass used in high level waste encapsulation. The second deals with the effects of residual chloride contamination on nuclear reactor contaminants. Finally, some surface studies of the high temperature oxidation of Alloys 600 and 800 are outlined such characterizations are part of the effort to develop more protective surface films for nuclear reactor applications. ... 

A hterature review was conducted, which provided some materials as candidates for the section I (Bunsen) of the process ceramics (SiC, Si3N4, AI2O3), glass, fluocarbons, Tantalum and Zirconium or Ni alloys. However, corrosion tests are necessary to assess the maximum temperature and acidity acceptable conditions, the long tenn behaviour and the corrosion mechanisms. 

Morphological studies explain the mechanisms of E-glass corrosion. According to these studies, acid corrosion of E-glass is caused by calcium and aluminum depletion which varies depending on the acid type, fiber type, and acid concentration. Oxalic and sulfuric acids are more corrosive than nitric and hydrochloric acids. This difference is due to the fact that, in oxalic acid, precipitated products are formed which decrease the concentration of leachates in solution. In addition to the loss of mineral content, fibers develop axial and spiral cracks. Crack formation depends on the rate of material depletion. 

Glass fibres exhibit time-dependent fracture under a static load, which is referred to as static fatigue [36]. Since there is no time dependence of strength in a vacuum, it is considered that water is involved in the reduction in strength. Thus, a stress corrosion mechanism in condensed water is inferred. The chemical reactions associated with this process are given in Figure 12.17. 

The complementary nature of RBS and ERD analyses is illustrated in Figure 6.8, which shows Na and H depth profiles of the surface layers that form on sodium borosilicate glass corroded in pH 8 aqueous solutions for various times. Na is depleted from the outermost surface and replaced by H at approximately a one-to-one ratio. ERD analyses of B-profiles show no B-depletion, and RBS analyses show no significant Si-loss at pH 8 however, the corrosion mechanism is dependent on solution pH. 

McKinnis CL (1978) Stress corrosion mechanisms in E-glass fiber. In Bradt RC, Hassehnan DPH, Lange FF (eds) Fracture mechanics of ceramics vol. 4, Plenum Press, New York London, pp 581-596... 

While acid corrosion in glass fibers is diffusion-controiied and therefore /f-kinetics are expected, the process in aqueous and aikaiine soiutions is considered much more complicated because of the many influencing factors. The reaction kinetics depends on the (local) pH value. It is conventional opinion that, with the switch from a diffusion-controlled corrosion mechanism to an interfacial-controlled mechanism, a rapid shift from ft-to t-kinetics takes place, and the process follows linear t-kinetics except for short exposure times and low temperatures. However, in the literature, dependencies on t are also found, with values for a varying between 0.5 and 1 [819]. The chemical stability of glass fibers under alkaline attack is also significantly influenced by insoluble corrosion or reaction products on the fiber surface. 

Cockram, D.R., Fyles, K. M., Wilson, C.J. The Use of Radioactive Tracers to Investigate Corrosion Mechanisms of Glasses in Aqueous Solutions, Rivlsta della Staz. Sper. Vetro, 5 (1984), p. 83-89... 

Many different corrosion mechanisms operate within a melter. The types and severity depend on the glass composition, the composition and microstructure of the refractory, and the temperature. Corrosion rates tend to increase dramatically with temperature. This is an important reason why different refractories are often selected for different portions of the melter. It is also an important reason why the harder (higher melting temperature) glasses are generally more expensive to manufacture. Corrosion types include ... 

Latanision RM, Turn JC, Compeau CR, The corrosion resistance of metallic glasses in Mechanical Behaviour of Materials, Proceedings of ICM 3, Eds. K.J. Miller, R.F. Smith, Pergamon Press, Oxford, 1980 2 475-483. 

Waste corrosion. After canister failure, the waste form will begin to corrode in an environment of stagnant porewater. Vitrified waste dissolves at a very low rate and the corrosion rate is assumed to be constant with time (Grauer 1985). Arguments have been advanced for possible acceleration mechanisms (formation of crystalline secondary products which lower silica concentration and thus accelerate glass corrosion) but long-term (c. 5 year) experiments... 

U. Schmalenbach and T. Weichert, Checker material of regenerative chambers in soda-lime glass-melting furnaces—Corrosion mechanism and lining recommendations, Sprechsaal, 120 386,1987. 

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