Contribution a l'etude de la corrosion par le gaz carbonique des alliages de zirconium.

Guerlet, J.P.; Lehr, P.

doi:10.1016/0022-3115(68)90023-8

Cited by 5 publications

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“…Investigations on the oxidation properties of Z r -N b alloys containing 2-3 w / o (weight per cent) Nb at elevated temperatures have been only carried out to a limited extent (1)(2)(3)(4)(5). The reaction kinetics over the temperature range 300~176 are characterized initially by continuously decreasing rates followed by transitions to more rapid approximately constant rates.…”

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“…At temperatures less than the a + ~ eutectoid point at 610~ a martensitic alloy oxidizes more rapidly than the Widmanstatten-structured alloy (2,3). The zirconia scales may contain small amounts of the intramolecular oxide, 6ZrO2-Nb205 (2)(3)(4)(5). At t e mperatures higher than 900~ parabolic oxidation of a E-structured alloy gives rise to the formation of an oxygen stabilized columnar zone of a-Zr plates beneath the scale (4,5).…”

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“…The zirconia scales may contain small amounts of the intramolecular oxide, 6ZrO2-Nb205 (2)(3)(4)(5). At t e mperatures higher than 900~ parabolic oxidation of a E-structured alloy gives rise to the formation of an oxygen stabilized columnar zone of a-Zr plates beneath the scale (4,5). The objectives of this investigation, accordingly, were to determine the temperature dependence of the oxidation kinetics for the alloy in the a + ~ and ~-Zr structures and to examine the m o rphological development of the scale and a-Zr columnar layer in the ~-Zr alloy.…”

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Oxidation Properties of a Zirconium-2.7 w/o Niobium Alloy in the Temperature Range 650°–1000°C

Urbanic

Smeltzer

1972

J. Electrochem. Soc.

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A B S T R A C TThe reaction kinetics and structures of the alloy/oxide composite system were determined for a Zr-2.7 weight per cent Nb alloy exposed at t e m p e r atures over the range 650~176 in oxygen at 1 atm pressure. These kinetics may be represented by a parabolic-linear relationship. The zirconia scales contained small amounts of the intramolecular oxide, 6ZrO2 9 Nb2Os. An investigation was carried out on the morphological development of the col u m n a r scale and the underlying layer of oxygen stabilized ~-Zr plates in the $-Zr alloy during parabolic oxidation. The sequence of the reaction product layers was consistent with predictions from the Z r -N b -O phase diagram.Investigations on the oxidation properties of Z r -N b alloys containing 2-3 w / o (weight per cent) Nb at elevated temperatures have been only carried out to a limited extent (1-5). The reaction kinetics over the temperature range 300~176 are characterized initially by continuously decreasing rates followed by transitions to more rapid approximately constant rates. At temperatures less than the a + ~ eutectoid point at 610~ a martensitic alloy oxidizes more rapidly than the Widmanstatten-structured alloy (2, 3). The zirconia scales may contain small amounts of the intramolecular oxide, 6ZrO2-Nb205 (2-5). At t e mperatures higher than 900~ parabolic oxidation of a E-structured alloy gives rise to the formation of an oxygen stabilized columnar zone of a-Zr plates beneath the scale (4, 5). The objectives of this investigation, accordingly, were to determine the temperature dependence of the oxidation kinetics for the alloy in the a + ~ and ~-Zr structures and to examine the m o rphological development of the scale and a-Zr columnar layer in the ~-Zr alloy. ExperimentalA t h e r m o g r a v i m e t r i c technique was employed to m e asure the oxidation rates of alloy plates and spheres. The assembly which has been described contained an Ainsworth, Type AU-1, balance for continuously recording weight gains up to 400 mg to a sensitivity of 0.02 mg (6). Test temperatures w e r e controlled to •176 A specimen was lowered into the reaction zone and held for 15 min to ensure t e m p e r a t u r e equilibration after the assembly had been flushed with argon purified of oxygen and water vapor. The assembly was subsequently pumped down to less than 10 -4 Torr and oxygen, 99.99% pure, then admitted to a pressure of 760 Tort. At the termination of a run, the specimen was quenched by rapidly raising it into the air-cooled portion of the assembly.The material was a Zr-2.7 w / o Nb alloy received as a 2 m m thick sheet and as a bar. Analyses for i m p u r i -* E l e c t r o c h e m i c a l Society A c t i v e M e m b e r . K e y w o r d s : z i r c o n i u m -n i o b i u m alloys, o x i d a t i o n kinetics, o x i d e scale, alloy microstructures.ties have been presented, the residual oxygen content in the alloy being 1100 ppm (2). Plates prepared from the sheet, 2 • 1 • 0.2 cm, were wet abraded on 220 to 600-grit silicon carbide papers, polished on 6 ...

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