Untersuchung über das Korrosionsverhalten von Zirkoniumlegierungen. IV. Das Lochfraßverhalten Zirkoniumlegierungen

Abstract

stellt init beliebigen h-Werten partikulare Losungen der Differentialgleichung ( A 3.4) dar. Die Funktion Die zweite Bedingung liefert C o = K1 + K 2 , ( A 3.6) die dritte Bedingung liefert Cs = K 2 . 1st ebenfalls eine Losung der Differentialgleichung ( A 3.4). Die vollstiindige Losung wird als Linearkombination dcr partikularen Losungen angesetzt: Hieraus folgt Die erste Bedingung Iiefert, wenn man beachtet, daf3 ( A 3 7) 2 t 1 2 m e-v2 d77 + K 3 -I 6 0 Die Konstanten K 1 bis K 3 ergeben sich aus den Randbe-t +.+ 0 0 P I 2 G e J d p =tlP--e-q2 d?7=* 2 Iim I +. dingungen Die Konstanten h, und A, werden wie folgt angesetzt ist, die Gleichung Setzt man diese beiden Werte ein und berucksichtigt Gleichung ( A 3 . 3 ) , so folgt Hieraus folgt K3 = ~ ( G o -Cs) 11 2 Die Losung lautet demnach ( A 3.9) 377 C = K I . e x p ( --f ) + K 2 + K DC Die Konstanten werden wie folgt bestimmt: Fur f + + 0 und t = 0 ist C = Cs, fur [ = 0 und t > 0 ist C = Co, fiirc = m m d t > O ist C = C s ( A 3 . 1 0 ) = ( 1 8 ) Electrochemical investigations into the resistance o f a number o f Zr-alloys in different solutions against pitting corrosion have shown that additions of Va-and VIa-group metals and in particular Ti improve the resistance o f pure Zr. Metals forming local elements decrease pitting corrosion resistance. Minor amounts o f Fe, N i and Cr have practically no influence. The pitting corrosion resistance of Zr and its alloys decreases with increasing concentration of chloride ions in the solutions. Additions of S04-ions retard the beginning of the pitting but do not shift the pitting corrosion potential. N03-ions on the other hand produce a real inhibition. Newly developed methods for the quick determination of the pitting corrosion potential were very useful f o r the described investigations.

Effect of Impurity Elements on Localized Corrosion of Zirconium in Chloride Containing Environment

“…(2), Sn is found in commercially available pure Zr because recycle scraps of Zr alloys are often used for the refining process, and (3), the alloying of Sn to Zr is considered to inhibit its corrosion resistance. 11,[22][23][24] Therefore, Zr-Sn alloys were also prepared in this study to ensure the effect of Sn on its corrosion behavior. From the experimental results, the mechanism of the localized corrosion of Zr in chloride-containing environments is discussed.…”

Corrosion behavior of new quaternary ZrNbTiAl alloys in simulated physiological solution using electrochemical techniques and surface analysis methods

“…Alloying Zr with Ti is an established procedure to improve the corrosion resistance of this metal, especially in relation to pitting corrosion [62,63]. Thus, a Ti content in Zr greater than 10 wt.% shifted positively the pitting potential in aqueous HCl solution, and for a Ti content greater than 50 wt.%, the pitting potential reached values comparable to those of pure Ti [63].…”